Differential Diagnosis in Neurology

5.2. Cranial Nerve II

Anatomy of the Retina

• General Features:
  • Retinal pigment epithelium is the origin of rods and cones; internal to the choroid
  • Rods and cones then project to bipolar and amacrine cells; these project to ganglion cells; further projection to lateral geniculate body or superior colliculus
  • Rhodopsin pigment (glycoprotein) of the rods; reacts to wave lengths from 400–800 mm; 100 million rods; more numerous in the fundus
  • Seven million cones; react differentially to wave lengths of light; fovea in the center of macula; 0.35 mm area of greatest visual discrimination
  • 1.2 million ganglion cells of the inner retina:
    • Smaller receptive fields in the posterior pole
    • Ganglion cells concentrated in posterior pole
    • One to one connection with ganglion cells
    • Periphery of globe: extensive overlapping of receptive fields subserving ganglion cells
    • Relative sparing of peripheral vision with ganglion cell disease
    • Ganglion cells specialized for spatial discrimination project to the lateral geniculate body (LGD); those specialized for movement and fixation reflexes synapse on the SC (superior colliculus)
    • Ganglion cells closer to the disc send axons through the entire nerve fiber layer
    • Papillomacular bundle temporal side of the disc that course from the macula straight to the nerve head; superior macular fibers arch superiorly and then descend to the disc; the reverse occurs for inferior temporal fibers
    • Neurons subserving a macular strip centered in the fovea project bilaterally
• Clinical presentation:
  • Normal visual acuity and contrast sensitivity if macula is spared
  • Color perception: blue affected greater than red with photoreceptor lesions
  • Visual field deficit:
    • Central (optic nerve; tip of the occipital lobe)
    • Cecocentral (between fixation and blind spot); toxins, e.g. alcohol
    • Arcuate (glaucoma)
    • Sectorial ring with nasal step (glaucoma)
    • Altitudinal (optic nerve, chiasm, occipital lobe)
  • Micropsia (CPS)
  • Normal pupillary light reflex (cortical lesions)

Optic Nerve and Optic Chiasm

• General Features:
  • Intraocular position:
    • Optic nerve head 1 mm
    • Fourteen small vessels across the disc
    • Lamina cribrosa seen (within the cup)
    • Slight nasal blurring (normal)
    • Blood supply: watershed between central retinal artery (ophthalmic) and posterior ciliary arteries (external carotid)
  • Intraorbital portion:
    • 25 mm length
    • Surrounded by fat in the cone between the extraocular muscles
    • Apex of the cone is open to optic foramen and the superior orbital fissure
    • Ophthalmic artery, ciliary nerves and ganglia, nerves to extraocular muscles are in close proximity to the optic nerve
  • Intracanalicular segment:
    • 9 mm length in the optic canal
    • Ophthalmic artery and sympathetic fibers of the carotid plexus travel with the optic nerve
  • Intracranial portion:
    • 4–16 mm (depending whether the chiasm is pre or post fixed in relation to the pituitary)
    • Optic nerve is above the carotid artery; above the sphenoid sinus; superior to the optic nerve A, segment of ACA, ACOA is superior to the optic nerve (anterior communicating artery) and chiasm
    • In 5% of individuals the chiasm overlies the anterior margin of the sella (prefixed) 12% it lies over the diaphragm a sella; 79% it is above the dorsum sellae; 4% it is post-fixed and lies behind the dorsum sellae
    • Inferior nasal fibers cross inferiorly in the chiasm and extend into the contralateral optic nerve (Willebrand's knee) to project laterally in the optic tract. Superior nasal retina fibers are medial in the optic tract
    • Nasal and temporal macula project crossed and uncrossed fibers
    • Macula fibers occupy the dorsal optic tract
    • Lateral geniculate body (LGD): I, IV, VI receive fibers from the contralateral eye; II, III, V – ipsilateral eye; macular region is represented centrally

The Optic Radiations

• General Features:
  • Upper bundle:
    • Origin is medial part of LGD; superior retina
    • Deep parietal white matter; projects to superior lip of calcine fissure
  • Central bundle: medial part of LGD; subserve the macula; projects to posterior calcarine fissure of both upper and lower lips
    • Lower bundle:
      • Lateral part of nucleus; lower retina
      • Meyer's loop; 5 cm behind tip of the temporal lobe; to lower lip of calcarine fissure
    • Anterior radiations:
      • Macular fibers run medially
      • Meyer's loop: fibers from contralateral eye medial to ipsilateral fibers

Vascular Supply of the Visual Pathways

• General Features:
  • Retina supplied by the central retinal artery (CRA) that branches from the ophthalmic artery 5–15 mm in the optic canal:
    • CRA pierces the nerve and divides into superior and inferior branch at the optic disc
    • Macula may be supplied by the cilioretinal artery that branches into superior or inferior divisions
    • Ophthalmic artery gives off several posterior ciliary arteries: they supply the optic disc, outer layers of retina and choroid
    • In a small percentage of patients the macula and papillomacular bundle is supplied by the cilioretinal artery that derives from the posterior ciliary arteries; may spare central vision after CRA occlusion
    • Posterior ciliary artery is involved by vasculitis; CRA ischemia is from microthrombi or emboli, migraine and hypercoagulable
    • CRA and posterior ciliary artery occlusion cause attitudinal VF deficit

Optic Nerve Vascular Supply

• General Features:
  • Proximal: ophthalmic artery, near the chiasm is supplied by the carotid and ACA
  • AcoA supplies the dorsum of the chiasm
  • Inferior chiasm supplied by:
    • Carotid
    • PCOM
    • PCA
  • Optic tract supplied by:
    • PCOM
    • PCA
    • Anterior choroidal artery
  • Lateral geniculate (LGD)
    • Anterior choroidal artery (laterally)
    • Lateral posterior choroidal artery (medially)
  • Optic radiations:
    • Upper portion: MCA
    • Lower portion: PCA
    • Occipital pole anastomosis:
      • Angular or posterior temporal arteries (MCA branches)
      • Calcarine branch PCA

Visual Acuity

• General Features:
  • Visual discrimination of fine details of high contrast
  • Macular function or its projections
  • Impaired by:
    • Changes in the shape of the globe
    • Refractory characteristics of the vitreous
    • Compressive and noncompressive lesions of the optic nerve; often prior to detectable field deficit
    • Medial chiasmal lesion decrease acuity bilaterally
    • Lateral chiasmatic lesions decrease acuity in the ipsilateral eye
    • Visual acuity remains intact if the crossing or noncrossing foveal fibers are intact
    • Retrochiasmatic bilateral lesions decrease visual acuity equally in both eyes

Contrast Sensitivity

• General Features:
  • Detects dysfunction of the macula, optic nerve and chiasm
  • Impaired contrast sensitivity detects more subtle defects than visual acuity

Color Perception

• General Features:
  • Decreased in areas of VF deficit
  • Desaturation for red in lesions of visual pathways
  • Retinal photoreceptor damage affects the perception of blue
  • Detects macular dysfunction (these projections affected in optic nerve and chiasm lesions)
  • Color vision loss usually parallels VA loss; optic neuritis color loss > VA deficits; in optic neuritis, chromatic sensitivity loss > luminance sensitivity
  • Impairment of color perception occurs with posterior VA defects
  • Bilateral lesions of the inferomedial occipital lobe; color blindness with normal visual acuity

Visual Field Defects

• General Features:
  • Macular lesion cause central defects
  • Retinal lesions causes inverted (superior lesion causes inferior deficit; lateral retinal lesion causes medial visual deficit)
  • Cecocentral defect:
    • Affects the macula
    • Papillomacular bundle
    • Peripheral defects in the nasal field are often from the retina or optic nerve
    • Small deep retinal lesions cause discrete deficits in appropriate part of the VF
    • Defects from lesions of nasal retinal fibers (temporal field lateral to blind spot) are sectoric. The nasal retinal fibers are straight rather than accurate
    • Retinal lesions that affect the superficial fiber layer cause fan-shaped arcuate defects with its tip pointing to the lesion and its base toward the nasal meridian. These defects are dependent on the fact that superficial layers of the nerve fiber bundle subserve peripheral vision
    • Ring VF defect; preserved central and peripheral vision to the defect:
      • Unilateral pericentral scotomata is macular
      • Retinitis pigmentosa (large peripheral ring scotoma)
      • Paracentral and arcuate scotomata suggest glaucoma
      • Fusion of superior and inferior arcuate defect cause ring scotomata
      • Horizontal step of ring shaped scotomata (mismatch of superior or inferior arcuate defect) suggests glaucoma rather than visual pathway lesion

Visual Inattention

• General Features:
  • Evident with double simultaneous stimuli
  • Often seen with incomplete homonymous defect
  • During recovery of dense VF deficit
  • Involvement of parieto-occipital or frontal cortical lesions R > L

Dissociation of Kinetic and static VF Response to Stimuli

• General Features:
  • Riddoch's phenomenon
  • Occipital lobe > optic tract > chiasm
  • Moving objects seen in otherwise dense static VF defect; possible extrastriate visual pathways are involved

Visual Field Defects

• Monocular defect:
  • Retina (associated with ophthalmologic defects)
  • Optic nerve
  • Early stage of chiasmatic defect (temporal portion of the central field of the ipsilateral eye)
  • Lesions of the most anterior portion of the calcarine cortex; crescent defect of the contralateral eye. Usually the reverse occurs with posterior calcarine cortex lesions in which the temporal crescent is spared
  • Monocular altitudinal defect:
    • Frequent macular sparing associated (macula bilaterally innervated)
    • CRA disease; macula also frequently supplied by cilioretinal arteries
    • Differential diagnosis:
      • Choroidal coloboma
      • Choroiditis
      • Glaucoma
      • Retinal detachment
      • Optic nerve hypoplasia
      • Ischemic optic neuropathy
      • Optic neuritis
      • Drusen
      • Optic nerve trauma
      • Sarcoid
      • Hematoma
      • Chronic papilledema
    • Bilateral altitudinal defects:
      • Most commonly occipital lobe vascular disease
      • Head trauma
      • Rarely: bilateral ischemic retinal or optic nerve disease

• Bilateral ring defect:
  • Bilateral occipital disease
    • Associated with vertical step defect
  • Retinal disease (rare)
• Bitemporal hemianopia:
  • Chiasmatic disease
  • Defect respects the midline
  • Differential diagnosis:
    • Chromophobe adenoma
    • Pituitary apoplexy (hemorrhage)
    • Craniopharyngioma
    • Meningioma (sella)
    • Dilated suprachiasmatic recess from increased intracranial pressure
    • Rathke's pouch cyst
    • Pituitary cancer or metastasis
    • Cushing's Syndrome
    • Prolactinoma
    • Multiple sclerosis
    • Glioma of the chiasma
    • Sarcoid
  • Junctional scotomata (kissing scotomata):
    • Compression of the ipsilateral optic nerve with extension of 2–3 mm into anterior chiasm
      • Ipsilateral optic nerve defect
      • Contralateral superior lateral defect
  • Homonymous hemianopsia:
    • Congruent: posterior lesion of the optic radiations
    • Incongruent: lesion of the optic tract
    • Congruency: the lesion in one field is superimposable on the lesion of the other field
    • Anterior choroidal artery stroke:
      • Sparing of a horizontal sector
      • Incongruous defect of upper and lower quadrants
      • Quadruple sectoranopia
      • Lateral (LGD) lesion
      • Infarction of the hilum and anterolateral part of LGD (lateral geniculate nucleus)
  • Superior homonymous quadrantic defect:
    • Large lesion of the inferior bank of the calcarine fissure. Small lesions cause scotomata.
    • Temporal loop of the optic radiations (Van Willebrand's knee)
    • Deep parietal lesions affect the dorsal component of the optic radiations to produce an inferior quadrantic defect
    • Quadrantic defects most often are due to optic radiation lesions
  • General points:
    • Macular sparing with occipital lobe lesions; dual blood supply; large macular representation
    • Bilateral homonymous cortical lesions:
      • Tip of the basilar pathology affecting both PCA arteries
      • Seriatim lesions
      • Anoxic insult
      • Cardiac surgery (emboli and watershed infarction)
      • Complication of cerebral angiography
      • Migraine
      • Embolus to top of the basilar
      • Tentorial herniation (PCA occluded)
      • Anton's syndrome occurs if complete
        • Denial of blindness (confabulation)
        • Normal pupillary light reaction
        • May have small peripheral visual field spared; able to avoid large objects
        • Early euphoria
    • Lesions of anterior optic pathways:
      • Difficulty in reading
      • Dimness of vision
      • Attitudinal defects: downward shade or looking over the horizon
    • Vertical hemianopsia:
      • Bumping into objects in the blind field
    • Metamorphopsia and micropsia:
      • Distortion of objects; decreased size of objects
      • Most often retinal disease; may be from complex partial seizure (occipital or posterior temporal lobe)
      • Displacement of retinal cells
        • Micropsia separation of photoreceptors by edema
      • Distorted perception noted with migraine
      • Optic neuritis:
        • Movement phosphenes
        • Flashes of light with eye movement in the dark
        • Spontaneous discharge of demyelinated Mechanosensitivity fibers
      • Chiasmatic lesions:
        • Respect the midline vertical meridian
        • Lose central vision with convergence; the temporal VF defects merge
        • Image displacement (in face of normal extraocular muscles)
          • Small ocular muscle imbalance compensated by binocular fixation with full fields; with VF deficit become manifest with Bitemporal defect
          • Horizontal or vertical deviation of the images from either eye
          • Hemifield slide phenomenon

Ophthalmoscopic Observations

• Optic atrophy:
  • Sharp disc margins
  • Loss of the lamina cribrosa
  • Decreased cup disc margin ratio
  • Sharpness of disc margin (particularly temporally)
  • Decreased visual acuity
  • Loss of disc capillaries (<14)
  • Thinness in retinal arteries
• Glaucoma:
  • Deepening of the cup
  • Nasalization of the cup
  • Present by the time of decreased visual acuity or arcuate or Bjerrum (step) scotomata appear
• Papilledema (in order of occurrence):
  • Fat veins
  • Loss of venous pulsations
  • Hyperemic disc (dilation of the capillaries on the disc surface)
  • Protrusion of the lamina cribrosa
  • Loss of disc the margin: superior prior to inferior; last is temporal; nasal margin is always slightly blurred
  • Slit hemorrhages off the disc capillaries
  • Retinal folds
• Optociliary shunt veins:
  • Appear at the disc margin or the disc
  • Increased pressure in the optic canal or intracranially
  • Anastomosis between the central retinal vein and the peripapillary choroidal venous system
  • Differential Diagnosis:
    • Optic nerve sheath meningioma of Schwalbe
    • Optic nerve glioma
    • Neonatal hydrocephalus
    • Pseudotumor cerebri
    • Drusen of the optic disc
    • Glaucomatous atrophy
    • Chronic atrophic papillitis
    • Central retinal vein occlusion
    • Arachnoid cyst
    • Neurofibromatosis
    • Optic nerve coloboma
    • Osteosclerosis
    • Hamartoma of the disc

Pupillary Light Reflex

• General Features:
  • Optic nerve fibers leave the visual sensory pathway prior to the LGD; synapse in the pretectal region (dorsal midbrain)
• Clinical presentation:
  • Direct simulation detects relative afferent defect
  • Light in the normal eye constricts both pupils; swinging light to the affected eye causes it to dilate to direct light
  • Probably not related to defect of the retina or the optic nerve but to a defect in the neurons of the midbrain that controls the reflex ("slippage of the reflex")
  • Differential diagnosis of relative pupillary afferent defect:
    • Optic tract disease (light directed to affected retinal photoreceptors); Behr's pupil
  • LGD, optic radiations and cortical lesions do not affect pupillary light reflex

Optic Nerve Lesions

• General Features:
  • Visual acuity (decreased)
  • Contrast sensitivity (decreased)
  • Color perception (red most affected, color desaturation; red appears brown)
  • VF defect:
    • Central scotomata
    • Arcuate defect
  • Gaze affected blindness (rare); phosphenes common
  • After images to bright light (decreased)
  • Relative pupillary afferent defect (Marcus Gunn phenomenon)
  • Pulfrich T's pendulum phenomenon (Rarely present); elliptical optic illusion of a horizontal moving object due to differential conduction (slower) of the affected nerve
  • Papilledema
  • Optic atrophy
  • Drusen, hematoma, infection, inflammation of the disc
  • Congential disc disease (coloboma)
  • Nerve fiber layer atrophy

Optic Chiasm

• General Features:
  • Visual acuity: may be decreased bilaterally (several areas may have macular and foveolar fibers; medial chiasm and posterior areas)
  • Decreased acuity in the ipsilateral eye form lateral lesion (uncrossed fibers)
  • Color perception (red most affected; color desaturation common)
  • VF defects:
    • Junctional scotomata
    • Ipsilateral temporal or paracentral defect (anterior chiasm)
    • Bitemporal superior quadrantanopsia (paracentral chiasm; inferior lesion)
    • Impaired central vision on convergence
    • Hemislide of the visual field with pseudo diplopia (VF defects interferes with convergent control of minor ocular motor imbalance)
    • Marcus Gunn phenomenon with ipsilateral chromatic lesion
    • Nerve fiber layer atrophy of straight nasal retinal fibers; "bow-tie" configuration (crossing fibers)

Vascular Disease of Cranial Nerve II

• General Features:
  • Central retinal artery emboli:
    • Source: carotid atheromata; arch of the aorta; heart valves
    • Emboli lodge at branch points of secondary and tertiary vessels
    • Birefringent yellow cholesterol plaques; appear larger than the occluded vessel; (Hollenhorst plaques)
    • Shade VF loss (descending)
    • 1–2 minutes in duration; embolus moves peripherally
    • Rare ophthalmic artery aneurysm with embolus
  • White emboli:
    • Platelet fibrin
    • Heart valve origin
  • Fat emboli (long bone fracture)
  • Air emboli
    • Surgical procedures (ENT; heart surgery)
  • Transient Monocular Blindness:
    • Emboli
    • Arteritic processes
    • Vasospastic migraine
    • Distal field ischemia (carotid artery)
  • Ischemia of the Chiasm and CN II from Surgery:
    • A-COM aneurysm clipping; disruption of dorsal chiasmatic blood flow
    • Ophthalmic artery surgery or A-COM aneurysm; disruption of blood supply to optic nerve
    • Posterior communicating artery aneurysm; disruption of ventral chiasmatic blood supply
    • Posterior cerebral artery ischaemia; distal optic nerve defect ischemia
  • Anterior ischemic optic neuropathy:
    • Hypertensive cardiovascular disease
    • Swollen optic disease that resembles papillitis
    • Central scotomata
    • Elderly patients
    • Ocular pain
  • Watershed ischemia of optic nerve head:
    • Disc: watershed of the central retinal artery form the ophthalmic and posterior ciliary arteries from the ophthalmic artery
    • Vasculitic processes (giant cell arteritis)
    • Distal field ischaemia
    • Central scotomata
  • Delayed effects of X-RT:
    • X-RT affects the vascular endothelium
    • 1–5 years post X-RT ischemia of the blood supply to vasovasorum of the optic nerve and chiasm or the major arteries: carotid, ophthalmic or posterior ciliary arteries

Hereditary Disease of the Optic Nerve

• Retinal degeneration with secondary optic nerve degeneration
• Syndromic retinitis pigmentosa
• Glaucoma
• Hereditary sensory motor neuropathy (AD, AR, X-linked)
• Familial spastic paraparesis Type II
• Hereditary spastic paraparesis with macular degeneration
• Leber's hereditary optic atrophy (LHON)
• Behr's syndrome cerebellar (degeneration with optic atrophy; 3-methyl-glutaconic aciduria)
• Progressive plantar keratoderma (PPK) with optic atrophy
• Familial spastic paraparesis; X-linked q21
• Wolfram syndrome

Vasculitis

• Churg–Strauss Disease
• Giant cell arteritis
• Tolosa–Hunt syndrome
• Behçet's diseas
• Granulomatous angiopathy
• Sjögren's syndrom
• Kawasaki's disease
• Eales disease

Immune Mediated Optic Neuropathy

• Multiple sclerosis
• Devic's disease
• Associated with AIDP
• Associated with CIDP
• IV drug abuse (autoimmune reaction to adulterants; Librium or quinine)
• Post immunization
• Adult subacute sclerosing panencephalitis (SSPE or Dawson's encephalitis)

Infections

• CMV (retinal ganglion cells)
• HIV (direct nerve involvement)
• Cat scratch fever (Rochalimaea henselae; retinal involvement)
• Cryptococcosis (compression of the nerve under the dura)
• Tuberculosis (meningeal, proliferative endarteritis and retinal involvement)
• Syphilis (retinal, disc, central pathways)
• Nocardia (invasion of blood vessels)
• Aspergillosis (invasion of blood vessels)
• Mucormycosis (orbital, blood vessel and cavernous sinus involvement)

Tumor

• Lymphoma:
  • Mass: most often in inferior and anterior orbit
  • Superior rectus muscle may be preferentially involved
  • Displacement of lobe > exophthalmos
  • Optic nerve affected by compression
• Chloroma:
  • Associated with myelogenous leukemia and lymphatic leukemia
  • Green mass
  • Base of the skull; predilection for the orbit
  • Bilateral tumors
  • Hemorrhage into the lids and orbit is common
• Malignant Melanoma:
  • Primary malignant melanoma is rare (choroid pigment epithelium)
  • Recurrence after enucleation
  • Brownish mass
  • Extrusion of an implant or poor retention of a prosthesis from tumor growth
• Rhabdomyosarcoma:
  • Exophthalmos a presenting sign
  • Eye displaced out and down > forward; mass upper nasal orbit
  • Progresses rapidly without pain
  • Ptosis 1/3 of patients
  • 10% nose bleed and pain around the orbit
  • Frequent conjunctival chemosis and congestion
  • Venous congestion; retinal striae; rare disc edema
• Retinoblastoma:
  • Almost always childhood illness
  • 25% are bilateral
  • Initiated intraocularly; grows along the optic nerve
  • May grow through the sclera to form an orbital mass
  • Endophytum type:
    • Inner retinal layers
    • Pink color (blood vessels)
    • Grows into vitreous cavity
  • Exophytum type:
    • Outer retinal layers
  • May grow through central optic pathways
  • Necrosis and calcification in the orbit
  • May present with leukocoria (white pupil)

Differential Diagnosis of Leukocoria

• Glioma
• Retrocentral fibroplasias
• Persistent hyperplastic vitreous
• Nematode endophthalmitis
• Massive retinal fibrosis
• Retinoblastoma
• Metastatic retinitis
• Retinal dysplasia
• Coat's disease:
  • Disease of young men
  • Late 20's
  • Unilateral
  • Massive macular exudative retinitis

Tumors Affecting the II Cranial Nerve and/or the Orbit

• Meningioma of Schwalbe (optic nerve sheath; perioptic meningioma)
• Sphenoid wing meningioma
• Lymphoma
• Rhabdomyosarcoma
• Leukemia (particularly CLL)
• Chloroma
• Optic nerve glioma (neurofibromatosis 1; chromosome 17)
• Ganglioneuroma
• Hemangioma of the orbit
• Hypereosinophilia (involving II directly)
• Carcinomatosis of the meninges (lung > breast > GI tract > melanoma)
• Metastasis (breast, lung, melanoma)
• Dermoid
• Epidermoid

Tumor of the Orbit

• General Features:
  • Optic disc swelling with orbital lesions:
    • Proptosis may be minimal or absent
    • Graves orbitopathy
    • Optic glioma
    • Carotid cavernous fistula
    • Perioptic meningioma:
      • Slowly progressive visual loss
      • Ptosis with disc swelling
      • Papillary retinal ciliary venous shunts
  • Funduscopic changes induced by retrobulbar mass lesions:
    • Compression of the posterior wall
      • Choroid retinal striae
    • Compression of the equator of the globe
      • Diffuse retinal flattening
    • Dilatation and tortuosity of veins as a consequence of high pressure
  • Orbital cysts:
    • Congenital:
      • Dermoid
      • Teratoid
      • Ischemia
      • Meningocele
      • Encephalocele
    • Acquired:
      • Implantation
      • Serous
      • Parasitic (hydatid or cystercercosus)
  • Epidermoid:
    • Present at puberty
    • Upper and outer quadrant of the orbit; near lacrimal gland; deep in the orbit
  • Dermoid:
    • Cysts may have multiple diverticulae
    • Choroidal involvement
    • Most common location on the globe is the limbus; upper outer quadrant
    • Associated with coloboma of the lid and aniridia
    • Inflammatory reactions may appear around cysts that have perforated
    • Deep dermoids compress the optic nerve
    • Primary cholesteatoma of the orbit cannot be differentiated from a dermoid except histologically
    • Dermoids may span the orbit and cranial vault
  • Orbital bone cysts:
    • Cysts contain channels with thin or thick septa
    • Orbital roof in location
    • Blood may be present in the cyst
  • Cystic orbital teratoma
  • Congenital cystic eyeball
  • Orbital encephalocele
  • Meningocele

Vascular Masses of the Orbit

• Orbital lymphangioma:
  • Seen on the lids and in orbits
  • Resemble cavernous hemangioma (spaces contain lymph)
  • Benign, slowly progressive tumor
  • Involve the lymph and vascular system
  • Usually present in children
  • Approximately 50% have involvement of lids, conjunctiva, face and palate
  • Hemorrhage into tumor occurs frequently
  • Plateau of growth by adulthood
• Hemangioma:
  • Frequently encountered orbital tumor (23% of all orbital tumors)
  • Cavernous hemangiomas:
    • Epithelium lined spaces
    • Long and encapsulated
  • Racemose form:
    • Completely formed blood vessels; veins predominant
    • Isolated masses of blood vessels
    • May pulsate
    • A-V aneurysms in the retina
  • Tumors occur within the muscle cone
  • Proptosis; straight forward without deviation
  • Engorgement of retinal vessels, disc edema, loss of vision
  • Ocular pulsation may develop; occasional ocular bruit noted
  • Intermittent exophthalmos
• Hemangioleiomyoma:
  • Composed of thick walled vessels
  • Contain smooth muscle
  • Encapsulated tumor
• Hemangioendothelioma:
  • Originates from endothelial cells
  • Contain anastomosing vascular channels
  • May be malignant; may metastasize
  • May occur in the soft tissue of the body
• Hemangiopericytoma:
  • Proliferating cell is the pericyte; potentially malignant
  • May invade the bone and erode into the cranial cavity

Lacrimal Gland Tumor

• Mixed tumor:
  • Benign or malignant
  • 50% of the epithelial tumors of the lacrimal gland
  • Myxomatous stroma and epithelial elements
  • Benign mixed tumors:
    • Most common type of epithelial tumor of the lacrimal gland
    • Encapsulated
    • May recur and invade bone
• Adenoid cystic carcinoma:
  • Lacrimal gland > frequency than salivary gland
  • 50% of epithelial tumors of the lacrimal gland are carcinomas (adenocystic most common)
  • Adult tumor
  • Presents as a lump in the upper outer orbit
  • Exophthalmos slight or late
  • May have early disc edema
  • Decreased vision due to optic nerve pressure
  • May invade bone and cause pain

Sarcoma of the Orbit

• Specific type:
  • Rhabdomyosarcoma
  • Osteosarcoma
  • Chondrosarcoma
  • Myxosarcoma
  • Fibrosarcoma
• Primary, metastatic or involve the orbit by extension
• Rare tumors; 2% of those presenting with proptosis
• Leiomyosarcoma:
  • Usually arise in the uterus, GI or genitourinary tract
  • Originates from smooth muscle of blood vessels
  • Grow rapidly and metastasizes
• Fibrosarcoma:
  • Rare in the orbit
  • Extend locally rather than metastasize
• Chondrosarcoma:
  • Arises from bone soft tissue
  • Orbital tumors arise from bone
  • Affect orbit by extension (greater wing of sphenoid)
• Osteosarcoma:
  • Associated with fibrous dysplasia
• Liposarcoma:
  • 20% of malignant tumors of soft tissue
  • Extremely rare in the orbit
• Malignant granular cell myoblastoma:
  • Average age of onset 20–30 years
  • Metastases or reoccurrences occur after many years
  • May have bone formation in the tumor
• Primary orbital melanoma:
  • Majority of orbital melanotic tumors are extension of choroidal melanoma
  • Possible association with nevus of ota (benign melanosis of the skin innervated with orbital melanoma)
  • Glioma of the retina has been described
• Post irradiation orbital tumor:
  • Sarcoma following X-RT for retinoblastoma
  • Develops many years following therapy (4–25 years)
  • Fibrosarcoma, carcinoma, mesenchymal tumors are
  • First evidence of tumor is in the area treated
  • Mass is frequently at the orbital margin
• Metastatic tumors:
  • Posterior choroid predilection
  • Left side involved > right; more direct course of the carotid artery
  • Twenty short posterior ciliary arteries; seven anterior ciliary arteries and two long posterior ciliary arteries. Metastasis more likely to go to short posterior ciliary arteries
  • Breast carcinoma to the uveal tract > orbit
  • Prostate metastases to orbit > uvea
  • Neuroblastoma 13% may occur after 20 years of age

Intraocular Metastatic Tumor

• General Features:
  • Occurs less than primary malignant intraocular tumors
  • Tumor emboli metastasize to uveal tract
  • Infectious emboli go to retina (smaller than metastatic tissue) course in the CRA circulation
  • Uveal metastases females > males
  • 25% of patients metastasis are bilateral
  • Breast carcinoma >50% of uveal cases
  • Lung metastasis: higher incidence of iris and ciliary body location
  • GI tract approximately 7% of Intraocular metastasis
  • Rare primary tumors: thyroid, liver, ovary, parotid glands, testicle, pancreas, kidney, uterus and bladder metastasize to the orbit
  • Majority of uveal metastases:
    • Choroid; temporal to the disc and near the macular
    • May extend to involve the iris and ciliary body
• Clinical symptoms:
  • Choroidal metastasis: visual impairment with rapidly progressive course (involvement of macula); retinal detachment with central scotomata
  • Rarely painful
  • Retinal elevation with an indistinct margin
  • Extraocular extension is rare; involvement of the retina is rare except by detachment
  • Anterior uveal metastasis:
    • May be no visual loss
    • Single or multiple metastases
    • Discreet nodule in the iris or ciliary body
  • Metastatic tumor of the retina:
    • Metastasis to the retina is rare
    • In a setting of wide spread metastases
    • Painless loss of vision
  • Orbital metastatic tumor:
    • Metastatic orbital tumors are less common than tumors that extend form the para nasal sinus or nasopharynx
    • Cause of unilateral proptosis (30%)
    • Female > male (breast cancer); 5–6th decade; L > R side
    • Breast > lung > prostate > uterus
    • Develops within few years of diagnosis of the primary
    • Clinical symptoms:
      • Diplopia first
      • Pain around the eye
      • Proptosis
      • Decreased vision, pain, extreme proptosis are late manifestations
  • Metastasis to adnexa
    • Rare
  • Metastases to the optic nerve:
    • Extremely rare
    • May involve the nerve or the nerve sheath
    • Progressive loss of vision

Orbital Complications of Sinus Disease

• Frontal sinusitis:
  • Mucocele:
    • Orbital mass
    • Exophthalmos
    • Naso orbital hyperostosis
  • Encysted empyema:
    • Upper inner angel of the orbit
    • Swelling and ptosis of the lids
  • Orbital osteoperiostitis
  • Diffuse orbital suppuration and abscess
• Maxillary sinusitis:
  • Osteoperiostitis
  • Optic nerve involvement
  • Lacrimal apparatus destruction
  • Iritis, iridocyclitis, neuroretinitis
• Ethmoidal sinusitis:
  • Mucocele (young patients)
  • Suppuration
  • Osteoperiostitis
• Sphenoidal sinusitis:
  • Cavernous sinus thrombosis
  • Orbital abscess
  • Optic neuritis
  • Ocular nerve palsy; VIth most frequent

Miscellaneous Orbital Pathologies Affecting CNII

• Thyroid ophthalmopathy:
  • Preceded by exophthalmos (no ocular deviation)
  • Orbital edema
  • Inflammation and fibrosisof the muscles
  • Insertions of the muscles not involved
  • Inferior rectus, more severely affected > medial recti > superior recti > oblique muscles
  • Vertical diplopia from asymmetric involvement of the inferior or superior recti is common early presentation
  • Abduction may cause extorsion of the globe (due to inferior oblique myositis)
  • Orbital congestion
  • Upper lid retraction (Dalrymple's sign)
  • Lid lag on down gaze (Von Graefe's sign)
  • Infrequent blinking (Stellwag's sign)
  • Convergent weakness (Moebius sign)
  • Optic nerve compression with scotomata (severe orbital congestion by swollen muscles at the orbital apex)
• Paget's disease (overgrowth of bone in the optic canal) with optic nerve compression
• Fibrous dysplasia of bone (compression of the optic canal)
• Osteopetrosis

Miscellaneous Conditions Affecting CNII

• Increased intracranial pressure:
  • Suprachiasmatic recess compresses the chiasm (transient visual obscurations)
  • Venous congestion of cavernous sinus with secondary orbital venous congestion
• Idiopathic pachymeningitis (in association with other cranial nerve involvement)
• Paraneoplastic involvement

Traumatic Optic Nerve Injury

• Orbital and facial fracture:
  • Penetrating orbital lesions
  • Blunt trauma to the eye:
    • Putative contusion of retrobulbar axons
    • Hemorrhage of nerve or nerve sheaths
  • Loss of vision during orbital surgery:
    • Post-operative orbital hemorrhage
    • Direct nerve injury
    • Repair of orbital floor fracture
    • After rhinoplasty
    • Blepharoplasty (orbital hemorrhage)
    • Neurosurgical procedures (face down); malposition of the head rest tamponades of globe; retinal choroidal infarction
  • Optic nerve tethered to bone:
    • Areas of injury:
      • Orbital opening of the canal
      • Canal 12 mm
      • Intracranial entrance of the canal compressed
    • Anterior frontal impact (rapid deceleration):
      • Falls, windshield trauma, frontal head trauma
      • Instantaneous severe visual loss

Radiation Injury of the Optic Nerve

• Usually secondary to X-RT of pituitary tumor or paranasal sinus
• Radionecrosis:
  • Proliferative endarteritis (endothelial cells)
  • Fibrinoid vessel necrosis
  • Necrosis of retrolaminar nerve substance
  • Delayed visual loss with optic atrophy

Thermal Burns

• Thermal burns of the body:
  • Delayed optic neuropathy
  • Bilateral involvement
  • Infants, children, young adults
  • Early visual loss due to diffuse cerebral edema or hypoxia

Nutritional and Toxic Optic Nerve Disease

• General clinical symptoms:
  • Insidious and slowly progressive
  • Affects central fields
  • Decreased acuity
  • Dyschromatopsia
  • Central scotomata
• Differential diagnosis:
  • Atypical central field loss with glaucoma
  • Macular cone dystrophy
  • Primary hereditary optic atrophy
• Vitamin deficiency:
  • Thiamine
  • B12 (pernicious anemia)
  • Cuban optic neuropathy
    • Multiple vitamin deficiencies
  • Nigerian civil war (optic neuropathy, nerve deafness and sensory ataxia; cassava roots and leaf diet; putative cyanide primarily in the roots)
• Drugs/Toxins:
  • Ethambutol (green cones affected)
  • Chloromycetin (seen in children with cystic fibrosis)
  • Streptomycin
  • Isoniazid
  • Chlorpropamide
  • Digitalis
  • Chloroquine (macular lesion)
  • Placidyl
  • Antabuse
  • Heavy metals
  • Methanol (optic nerve destruction; bloody papilledema)
  • Halogenated hydroxy quinolones: subacute; myelo-optic neuropathy (SMON)
  • Toluene (glue sniffing)
  • D-penicillamine
  • Intracarotid BCNU (glioma treatment)
  • Amiodarone
  • Hexachlorophene
  • 5-fluorouracil
• Tobacco-alcohol amblyopia:
  • Probable dietary deficiency of B-complex vitamins and protein
  • Elderly patients
  • Some patients have concomitant B12 deficiency
  • Thiamine therapeutic
  • Bilateral symmetric centrocecal scotomata (between blind spot and fixation point)
  • No nerve fiber defect is discernable
  • V.A. 20/200 is typical
  • Defect may extend across the vertical meridian
  • Vertical median respected in chiasmatic defects, rarely hemorrhages are seen on or off the disc (splinter variety); disc swelling (rare)
• Methanol:
  • Disc edema (may be hemorrhagic)
  • Associated encephalopathy
  • T2 MRI lesions in the BG (striatum)
  • Poor recovery
• Jamaican optic neuropathy:
  • Young adults; may be seen in all Caribbean islands
  • Rapidly progressive
  • Bilateral optic atrophy
  • Vision reduced to 20/200; dense central scotomata are noted
  • Patients may be well nourished and non-intoxicated

Toxic Optic Neuropathy

• General Clinical Features:
  • Subacute onset
  • Slowly progressive
  • Positive visual evoked potentials
  • Discrimination in contrast sensitivity (decreased)
  • Centrocentral or bitemporal VF deficit (chiasmatic involvement)

Masses of the Optic Disc

• Pseudopapilledema:
  • Anomalous elevation of the disc
  • Hylan bodies (drusen)
  • Gliotic dysplasia
• Fibrillary astrocytoma (NF type)
• Glial remnants of the hyaloid vasculature (their membranes or gray nodules attached to the disc)
• Capillary and cavernous hemangioma
• Racemose malformation (Wyborn Mason Disease)
• Melanocytoma
• Sarcoid granuloma
• Leukemic infiltrate
• Metastatic carcinoma

Clinical Features of Acquired Optic Nerve Disease

• Monocular defect is usual
• Bilateral defect:
  • Hereditary diseases
  • Toxic nutritional diseases
  • Rarely Devic's disease
• Defects of central VF function:
  • Decreased visual acuity
  • Decreased brightness
  • Hue desaturation
  • Afferent pupillary response
• Visual field defects:
  • Central scotomata
  • Arcuate nerve fiber defects
  • Altitudinal defects are most often vascular
  • Glaucoma, ischemia, drusen produce nasal defects
• Head and eye pain rare; retrobulbar neuritis is the exception
• Abrupt loss of monocular vision in the elderly is ischemic infarction of the disc; early disc swelling
• Slowly progressive monocular visual loss (months) suggests tumor compression (meningioma of Schwalbe)
• Insidious bilateral asymmetric centrocecal scotomata suggest toxic or nutritional intrinsic optic nerve disease
• Heredofamilial disease is bilateral and often associated with other neurological signs
• Prechiasmal optic neuropathy:
  • Inflammatory or vascular disease
• Chiasmatic disease:
  • Tumor (glioma; adenoma; craniopharyngioma)
  • Aneurysm (carotid, A-COM )
  • Cysts (Rathke's pouch remnants)

Differential Diagnosis of Optic Neuritis

• Autoimmune:
  • MS
  • ADEM
  • AIDP/CIDP (rare)
  • Post viral infection
  • Devic's
• Specific viral infection:
  • Measles
  • Mumps
  • Chickenpox
  • Viral encephalitis
  • HZ
  • HIV
• Contiguous inflammation:
  • Orbit
  • Sinuses
  • Meningeal
• Deep fungal infection:
  • Mucormycosis
  • Aspergillus
  • Cryptococcosis
• Syphilis
• Sarcoid
• Intraocular inflammation
  • Serous retinopathy
  • Neuroretinitis

Ischemic Optic Neuropathy (ION)

• Infarction of the disc:
  • Sudden loss of vision in the elderly
  • Most common cause of disc swelling after 50
• Involves prelaminar portion of the nerve
• Rarely associated with retrobulbar location from arteritis
• VF deficit:
  • Maybe maximum at onset
  • May progress for days to weeks
  • Recurrences in same eye are rare
  • No premonitory warning
  • No recovery
• Swollen disc:
  • Flame hemorrhages noted in edematous sector
  • Pain is rare
  • Presymptomatic phase of disc swelling in contralateral eye (rare)
• ION insufficiency in may be due to posterior ciliary arteries:
  • Infarction of retinal nerve fiber bundles in the disc (anterior to the nerve fiber bundle)
• Contralateral eye involvement 30–40% of patients
• Simultaneous bilateral disc infarction does not occur
• Higher incidence of DM and HCVD patients < 45 years of age
• Abrupt visual loss in the elderly without disc swelling may occur with:
  • Carcinomatosis of the meninges
  • Basal brain tumor

Giant Cell Arteritis

• General features:
  • Onset in 70–80 year old patients
  • Retrobulbar infarction occurs
  • Premonitory visual symptoms
  • Posturally sensitive visual loss
  • Female preponderance 3:1
  • Prevalence rate 60–69; 33/100,000 people
  • Worse visual loss than nonarteritic ION
  • May have CRA occlusion
  • Bilateral or rapidly segmental ION typical (usually days to weeks)
• Associated eye signs:
  • Hyperemia of conjunctiva and episcleral vessels
  • Mild corneal edema
  • Decreased Intraocular pressure
  • Iris rubeosis
  • Progressive cataract
  • Chorioretinal pigmentary changes (weeks after visual loss)
• Systemic signs and symptoms:
  • Weakness
  • Weight loss
  • Myalgia of proximal muscles; no demonstrable weakness
  • Fever
  • Above features constitute polymyalgia rheumatica
  • Sedimentation rate:
    • 80–100 mm/minute
    • Rare patient with normal sed rate
    • 35 to 40 mm (Westergren units) upper limit of ESR in elderly patients
  • Burning headache; sensitive hair

Rare Causes of Ischaemic Optic Neuropathy

• Cataract surgery:
  • 4–15 months post operatively
  • Sudden visual loss
  • Disc infarction occurred with both retrobulbar or general anesthesia
  • Second eye frequently involved (if operated)
• ION of the young:
  • Acute disc edema and visual loss
  • Cluster headache and migraine:
    • Unilateral or bilateral disc infarction (rare)
    • Sequential (rare)
  • Possible autoimmune vasculitis
• Ischemic disc swelling:
  • Marked or recurrent blood loss (G.I. tract)
  • Delayed for days to weeks
  • Rarely seen with by-pass surgery
• Uremic optic neuropathy:
  • Bilateral visual loss
  • Disc swelling
  • Severe renal disease; uremic state
  • Complicating features include:
    • Increased CSF pressure
    • Consecutive ION
    • Possible reaction to hemodialysis procedure
• Carotid artery disease
• Atrial fibrillation (emboli to posterior ciliary arteries)
• Coronary by-pass surgery
• Cardiac catheterization
• Eclampsia
• Acute intermittent porphyria
• PXE (platelet hypercoagulability)

Heredodegenerative Optic Nerve Disease

• Recessive (simple):
  • Severe visual impairment
  • Severe disc atrophy
  • Attenuation of arteries
  • Electro retinopathy normal
• Recessive (complicated):
  • Behr's Syndrome:
    • Optic atrophy
    • Mild mental retardation
    • Spasticity
    • Ataxia
  • Onset by nine years of age
  • Temporal disc pallor
  • Strabismus 2/3 of patients
  • Atrophy of optic nerves, tracts, lateral geniculate bodies; visual radiations and cortex
• Recessive optic atrophy and juvenile diabetes:
  • Childhood onset of optic atrophy
  • Visual loss 20/200
  • Disc pallor related to degree of diabetic retinopathy
  • Sensorineural hearing loss
  • Diabetes insipidus
  • Ptosis
  • Ataxia
  • Nystagmus
  • Seizures
  • Mental retardation
  • Abnormal ERG
  • Increased CSF protein
  • Short stature

Autosomal Dominant Optic Atrophy

• General Features:
  • AD inheritance
  • Onset 4–8 years of age (insidious)
  • VA from 20/30 to 20/70; asymmetry of arteries
  • Disc pathology:
    • Temporal pallor
    • Temporal sectoral excavation
    • Thinning of the papillomacular layer
  • Centrocecal enlargement of the blind spot
    • Mid zonal temporal depression
  • Full peripheral fields to white targets
  • Acquired blue yellow dyschromatopsia
  • Inverted peripheral fields to color

Specific Diseases

• AD optic atrophy with hearing loss
• Leber's hereditary optic atrophy

• General Features:
  • Mitochondrial genetics
  • Sudden loss of central vision
  • Onset second to 3rd decade
  • Male gender predominant
  • Peripapillary microangiopathy with arteriovenous shunting
  • Skeletal muscle defects
  • Cardiac muscle (pre-excitation syndrome)
  • Dystonia (striatal degeneration)
  • Cerebellar signs
  • Pyramidal system dysfunction
• Visual symptoms:
  • Loss of vision is rapid; VA 20/200
  • Acute phase: disc swelling occurs
  • Large dense central scotomata at fixation
  • Some patients regain vision

Dominant Pseudo Glaucoma

• General Features:
  • Deeply excavated optic disc
  • Slowly progressive glaucomatous VF deficit
  • Normal intraocular pressure
  • Normal outflow
  • Visual symptoms start at 20 to 35 years of age

Differential Diagnosis of the Swollen Disc

• Congenital:
  • Anomalous disc:
    • Tilted
    • Elevated
  • Hyalin bodies (drusen)
  • Gliotic dysplasia
    • Embryonic vascular remnants
• Intrinsic ocular disease:
  • Uveitis
  • Hypotony
  • Vein occlusion
• Inflammatory:
  • Papillitis
  • Neuroretinitis
  • Papillaphlebitis
• Infiltrative:
  • Lymphoma
  • Leukemia
  • Reticuloendothelial disease
• Systemic disease:
  • Anemia (Fe deficiency; B12)
  • Hypoxemia
  • Hypertension
  • Acute blood loss
  • Uremia
• Disc tumors:
  • Hemangioma
  • Glioma
  • Metastatic
• Vascular disease:
  • Ischemic optic neuropathy
  • Arteritic (giant cell)
  • Arteritis associated with collagen vascular disease
  • Juvenile diabetes
  • Proliferative retinopathies
  • Orbital tumors:
    • Perioptic meningioma
    • Glioma
    • Sheath "cysts"
    • Retrobulbar masses
• G raves' Disease
• Elevated Intracranial Pressure:
  • Mass lesion
  • Pseudotumor cerebri
• Hypertension
• Papilledema secondary to increased intracranial pressure:
  • Increased nerve sheath pressure
  • Optic nerve fibers:
    • Compressed by increased CSF pressure in subarachnoid space
    • Intraorbital part of optic nerve is affected
    • Water and protein diffuse into prelaminar region of the disc
  • Later events:
    • Venous obstruction
    • Nerve fiber hypoxia
    • Vascular telangiectasia
  • Rare causes of papilledema with possible differential mechanisms:
    • Cyanotic congenital heart disease
    • Decreased arterial oxygen saturation
    • Polycythemia vera
    • Systemic hypertension
    • Sleep apnea
    • Syringomyelia without hydrocephalus
    • Spinal cord tumors (increased CF protein; blocked absorption)
    • AIDP/CIDP (increased protein; blocked absorption; cytotoxic)
    • Diagnosed CSF deficits; (post meningitis)
• Basic mechanisms of papilledema:
  • Intracranial mass lesion (pressure and venous outflow obstruction)
  • Increased CSF production (choroid plexus papilloma)
  • Decreased CSF absorption (obstruction of Pacchionian granulations)
  • Obstructive hydrocephalus
  • Increased cerebral blood volume (AVM)
  • Venous outflow obstruction:
    • Atresia of venous sinuses
    • Obstruction of sinuses (inflammatory; clotting abnormalities)
  • Neck surgery
  • Jugular vein compression
  • Thoracic increased pressure
• Chronic Unilateral Papilledema:
  • Nerve sheath tumor
  • Intraorbital mass
  • Occasionally seen with true increased intracranial pressure
  • Previous optic atrophy of contralateral side (pseudo Foster–Kennedy syndrome)
  • Congenital nerve sheath anomaly
• Clinical manifestations:
  • Infants (open sutures); elderly patients (cortical atrophy) do not get papilledema
  • Usually days to weeks to develop; develops within hours with:
    • Severe head trauma (loss of autoregulation)
    • SAH (possibly second hemorrhage; acute obstruction of CSF absorption)
    • Greater than 60–80 ml intracranial hemorrhage
  • No visual acuity loss
  • Enlargement of blind spot
  • Normal pupillary light response
  • Visual fields intact
• Late papilledema:
  • Irregular peripheral VF constriction
  • Nerve fiber bundle defect
  • Transient visual obscuration:
    • Momentary dimming of vision
    • One eye at a time
    • Lasts a few seconds (less than 10–15 seconds)
    • Occurs with postural change or spontaneously
    • Clears completely
    • Pressure on the globe may reproduce the obscuration
    • Transient fluctuation of optic disc perfusion
  • Late VF loss has tendency to involve the nasal quadrants; constriction of the fields bilaterally (late sign)
• Evaluation of papilledema:
  • Blurring of nerve fiber layer: nasal earlier than superior > inferior > temporal
  • Veins engorged, dusky and tortuous
  • Spontaneous pulsations cease:
    • Seen in 80% of patients
    • Cease at 200 ± 25 mm H₂O
  • Splinter hemorrhages in nerve fiber layer, also occur in:
    • Drusen
    • Glaucoma
    • Elderly
  • Nerve fiber layer infracts: cotton wool spots
  • Disc hyperemia (dilatation of the superficial capillary bed on the disc); disc is progressively obliterated
  • Retinal folds (Patin's lines); circumferential retinal micro-folds; may extend to the macula
  • Rare concomitants of extreme papilledema:
    • Choroidal folds
    • Ischemic infarction of the disc
    • Infarction of the central retinal artery
    • Visual loss following placement of a ventricular shunt

Pseudotumor Cerebri

• General Features:
  • Definition
    • Raised intracranial pressure
    • Papilledema
    • No clinical or radiographic structural lesion noted
    • Normal CSF (exception is increased pressure)
  • Allowable neurological signs and symptoms:
    • Increased blind spot
    • VI nerve palsy (generalized intracranial pressure; nerve trapped in Dorello's canal under the petroclinoid ligament)
    • Tinnitus (may be pulsatile)
    • Visual obscuration (pressure on the chiasm from the suprachiasmatic recess)
    • Severe headache
• Clinical Features:
  • Female preponderance (teens through fifth decade)
  • Men approximately 20%
  • VF defects:
    • Increased blind spot
    • Arcuate nerve bundle defects (within central 30 degrees)
    • Defects nasally (along the horizontal meridian)

Differential Diagnosis of Pseudo Tumor Cerebri

• Congenital defects:
  • Aqueductal stenosis:
    • Forked aqueduct
    • Small multichannel variant
    • Congenitally small aqueduct (less than 3 mm)
  • Syringomyelia
  • Chronic sepsis (obliteration of the Pacinian granulations)
• Drugs:
  • Amiodarone
  • Tetracycline
  • Nalidixic acid
  • Tetracycline
  • Steroid withdrawal
  • Birth control pills
  • Lithium
  • Hypervitaminosis A
  • Hypervitaminosis D
• Venous thrombosis:
  • Venous anomalies of sinuses
  • Hypercoagulable state (sinus thrombosis)
• Hypothyroidism
• Pernicious anemia
• Iron deficiency anemia
• Addison's disease
• SLE
• Polycythemia vera
• Hypothalamic pituitary dysfunction
  • Stein–Leventhal syndrome

Time Course of Optic Neuritis

• Impairment of vision (central scotomata):
  • Progresses for hours or days
  • Maximum loss at one week
• Episode involves one eye:
  • Viral illness may involve both eyes in children
  • Devic's disease (may involve both eyes)
• Eye pain:
  • Globe, orbit or forehead; periorbital
  • Eye movement exacerbates pain (retrobulbar neuritis)
• Visual field loss:
  • Scotomata
    • Central
    • Centrocecal
    • Altitudinal and nerve fiber defects
    • General field constriction (rare)
• Decreased:
  • Color sense (hue desaturation)
  • Acuity
  • Contrast sensitivity
  • Depth perception
  • Decreased visual function with heat
• Visual function:
  • Improves within 1–2 weeks
  • May steadily improve over months
  • Rarely vision may not improve to functional levels
• Children more likely to have bilateral involvement
• Slow or poor recovery associated with more extensive lesions
• Disc edema is more often associated with anterior lesions; can occur with intracanalicular lesion
• Retinal perivenous sheathing (Rucker's periphlebitis retinae) more likely to develop in MS
• Uveitis (pars planitis) may be associated with MS, sarcoid and Behçet's disease

Atypical Optic Neuritis

• SLE:
  • Disc swelling and retrobulbar form
  • Possible small vessel ischemia
• Sjögren's syndrome
• Ulcerative colitis
• Para infectious:
  • Specific agents:
    • Chicken pox
    • Mumps
    • HZ
    • EBV
    • AIDP
    • CIDP
  • Clinical manifestations:
    • Visual loss is bilateral
    • Not direct viral involvement; putative immunologic cascade
    • Ten days to 14 days after infection
    • Good prognosis

Infections of the Optic Nerve

• Syphilis:
  • Neuroretinitis
  • Papillitis
  • Perineuritis:
    • Manifestations of second stage disease
    • Reoccurrence (particularly AIDS patients)
    • Slowly progressive atrophy (stage III)
    • Retrobulbar neuritis (rare)
• Neuroretinitis in secondary syphilis:
  • Clouding of the central retina
  • Hemorrhages
  • Migration of the pigment epithelium (retinitis pigmentosa; localizes around blood vessels)
  • Vitreous cellular debris
  • Disc swelling
  • Vasculitis
• Optic neuritis with HIV:
  • Associated infections:
    • Syphilitic optic perineuritis
    • CMV neuroretinitis; papillitis
    • Hepatitis B
  • HIV:
    • Bilateral optic neuritis
  • Lyme's disease
  • Toxoplasmosis (inflammatory papillitis)
  • Toxocara canes (inflammatory papillitis)

Slowly Progressive Optic Neuropathy

• Unilateral and bilateral visual field loss occurs in MS: central or centrocecal scotomata
• Sarcoidosis:
  • Disc granuloma
  • Optic nerve granula
  • Sheath infiltration

The Optic Chiasm

• General Features:
  • Anatomy:
    • The chiasm is in the suprasellar cistern
    • Floor of the suprachiasmatic recess
    • Eight to 13 mm above the plane of the clinoid processes
    • Intracranial nerve:
      • 45% inclined above the horizontal
      • 17± 2.5 mm in length
    • Lateral chiasm adjacent to the supraclinoid carotid artery
    • Anterior cerebral arteries are dorsal to the optic nerves
• Clinical Feature of Chiasmatic Disease:
  • Insidious progressive visual field loss
  • Asymmetrical
  • Tumors or aneurysms may cause fluctuations of vision
  • Nonparetic diplopia
  • Clumsiness with maneuvers that require depth perception
  • Diminished fusional capacity (non-fixed nasal fields):
    • Vertical and horizontal slippage:
      • Doubling of images
      • Gaps in a visual image
      • Steps in the perception of horizontal lines
  • Extinction of objects beyond the fixation point
  • Extraocular palsies with VF defect is associated with disease of the cavernous sinus
  • Optic nerve atrophy (frequent)
  • Vertical meridian is respected in chiasmatic defects

Rare Manifestations of Chiasmatic a VF Defect

• Bilateral atrophy and central scotomata
• Posterior chiasm angle defect:
  • Homonymous hemianopia
  • Depression of the inferior temporal VF near fixation
  • Decreased visual acuity
  • Optic atrophy

A Pseudo Chiasmatic VF Defect

• The vertical meridian (isopter defect "8–12") is involved in true chiasmatic defects
• Bilateral intrinsic eccentric central or centrocecal scotomata (intrinsic optic nerve or retinal disease)
• Nasal sector retinal disease (bilateral retinitis pigmentosa)
• Greatly enlarged blind spots from severe longstanding papilledema (Rare in the CT/MRI age)
• Congenitally tilted discs (inferior crescents; nasal fundus ectopia)

Congenital Defects

• Maldevelopment of the optic vesicles:
  • Unilateral or bilateral anophthalmos
  • Microphthalmic cysts
• Nerve hypoplasia:
  • Occurs in isolation
  • Occurs with ocular and forebrain malformations
  • Partial aplasia; micropapilla
• Bilateral optic nerve hypoplasia:
  • Decreased visual acuity
  • Nystagmus
  • Associated with forebrain or developmental defects
• VF deficits with optic nerve hypoplasia:
  • Smaller the disc in general > decreased vision
  • Decreased acuity
  • Temporal wedge and hemianopsia
  • Inferior altitudinal defect
  • Constriction of the VF
• Septo-optic dysplasia (De Mosier syndrome):
  • Short stature
  • Nystagmus
  • Disc hypoplasia
  • Holoprosencephaly
  • GH, ADH deficiency
  • Small pituitary
  • Mental retardation
• Dysplastic disc development:
  • Congenital tumor (hypoplastic truncated, irregularly oval)
  • Enlarged disc with optic glioma

Coloboma

• Congenital malformation that enlarges or distorts the nerve head circumference
• Faulty closure of the embryonic ventral fissure of the optic stalk and cup
• Enlarged disc that is excavated
• Retained glial and vascular remnants
• Posterior displaced disc within excavated peripapillary coloboma
• Excavated disc adjacent to retinochoroidal coloboma
• Pits within the nerve head
• Rare AD inheritance of coloboma: most are sporadic inheritance

Association of Disc Malformation and Forebrain Anomalies

• Basal encephalocele:
  • Pulsating exophthalmos (spheno-orbital encephalocele)
  • Hypertelorism with pulsatile nasopharyngeal mass
  • Frontonasal mass (fronto-ethmoidal encephalocele)
• Coloboma of the disc with hypertelorism or midface abnormality:
  • Highly associated with basal encephalocele
• Bilateral disc coloboma:
  • Bilateral retrobulbar arachnoid cyst
  • Dandy–Walker malformation
• Unilateral coloboma:
  • Carotid occlusion
  • Moya–Moya Syndrome with dolichoectasia
  • Absent carotid artery
• Pits of the disc:
  • Intrapapillary pearly grey dimples or slits
  • Contain glial elements
  • Located within scleral rim of disc margin
  • Single; temporal location > central > inferior, superior or nasal quadrant
  • Temporal pits associated with serous detachment of the macula
• Dysversion (tilted disc) and associated crescents of the optic disc:
  • Inferior crescent most frequent (inferior conus; Fuchs coloboma)
  • Adjacent retinal sector disorganization of the choroid and pigment epithelium
  • Inferior crescents associated with:
    • Myopia
    • Astigmatism
    • Decreased visual acuity
    • Decreased foveal reflex
• Disc abnormalities are associated with:
  • Hypertelorism
  • Crouzon syndrome
  • Apert's syndrome

Neoplasms Affecting the Optic Chiasm

• Adenoma of the pituitary:
  • Most common presentation 4–7th decade; uncommon in patients younger than 20
  • Non secretory adenoma:
    • Larger than secretory tumors
    • Present 50–60 years of age
    • Males greater than females
• Visual field deficits:
  • Superior bitemporal hemianopsia
  • Hemianopic scotoma near fixational area adjacent to the vertical meridian
  • Asymmetric
  • Eye with greater deficit may demonstrate loss of visual acuity
  • Posterior adenomas involving the optic tract:
    • Incongruous hemianopsia
    • Decreased central vision (ipsilateral eye)
    • Optic atrophy occurs
    • Rarely: Bjerrum arcuate scotomas (blind spot to nasal field; or terminate at the vertical meridian)
• Prolactinoma:
  • Most common pituitary tumor
  • Female > males most microadenomas (<10 mm in size)
• Clinical symptoms:
  • Females:
    • Amenorrhea
    • Galactorrhea
  • Males:
    • Decreased libido
    • Impotence
    • Gynecomastia
• Suprasellar cystic tumors:
  • Irritate the pituitary stalk or hypothalamus
  • Hyperprolactinemia

Pituitary Apoplexy

• General Features:
  • Acute change in volume of pituitary adenoma
  • Cause; necrosis, edema or infarction
    • Sheehan's syndrome: acute hemorrhage during pregnancy (rare in the West)
  • Mean age 50 years
  • Large percentage of glands demonstrate hemorrhage that were asymptomatic
  • Differential diagnosis of pituitary apoplexy:
    • Pregnancy
    • Adrenalectomy
    • Coagulation
    • X-RT
    • Trauma
    • Large adenoma
• Clinical presentation:
  • Acute severe retro orbital or infra brow pain
  • Rapid expansion into cavernous sinus with unilateral or bilateral ophthalmoplegia
  • Asymmetric ophthalmoplegia
  • Epistaxis or CSF rhinorrhea (erosion into the sphenoid sinus)
  • Pseudo meningitis
  • Decreased mental status or stupor (rare)
  • Late effects are pan hypopituitarism (rare)
  • Upward expansion: visual loss without ophthalmoplegia; downward expansion ophthalmoplegia without visual loss

Perichiasmal or Optic Nerve Compression by Meningioma

• Characteristic location:
  • Posterior perioptic foramina
  • Medial sphenoid ridge
  • Tuberculum sellae
  • Olfactory groove tumors (posterior extension)
  • Planum sphenoidale tumors (posterior extension)
• Clinical Features:
  • Slowly progressive monocular loss of vision
  • VF involvement:
    • Markedly asymmetric; extensive deficit on one side prior to contralateral VF deficit
  • More frequent in middle age women
  • Enlargement during pregnancy
  • Infrabrow or frontal headache occurs with supra sella meningioma
  • Onset of visual loss (unilateral) to subjective bilateral visual symptoms (1–8 years)
  • Perioptic (periorbital) eye pain that is exacerbated by movement; more common with optic neuritis
  • VF involvement:
    • Markedly asymmetric; extensive deficit on one side prior to contralateral VF deficit
  • More frequent in middle age women
  • Enlargement during pregnancy

Craniopharyngioma

• General Features:
  • Vestigial epidermoid remnants of Rathke's pouch; scattered cell rests in the infundibulohypophysial area
  • Calcification occurs in the tumor of 80% of children
  • Bimodal incidence: first two decades and again between 50–70 years of age
  • 2–4% of intracranial tumors
  • 20% of adult suprasellar tumor; 15% are infra sellar
• Clinical Presentation:
  • Visual deterioration
  • Endocrine deficits:
    • DI (diabetes insipidus)
    • Amenorrhea/galactorrhea
    • Hypopituitarism
  • VF deficit:
    • Asymmetric Bitemporal hemianopia (inferior quadrant)
    • Incongruous homonymous defect with decreased visual acuity with optic tract involvement
    • Chiasm and optic nerves may be infiltrated and thickened
    • Optic canal may be enlarged

Optic and Hypothalamic Glioma

• Middle age at onset
• Rapid severe unilateral visual loss; may have rapid bilateral visual loss (chiasmatic extension)
• Prognoses: death in months to two years
• Invasive malignant astrocytoma that may metastasize

Chiasmal Glioma

• More common than is orbital type
• Unilateral or bilateral visual loss
• More aggressive nature of chiasmatic gliomas in adults
• Primary malignant glioblastoma of visual pathways; rare in adults
  • Age of onset 40–50
  • Monocular loss of vision (optic nerve origin)
  • Retroorbital pain
  • Disc edema
  • Five to six weeks progressive visual loss to bilateral blindness
  • Death by two years

Dysgerminoma

• General Features:
  • Suprasellar location
  • Cell rests of the anterior floor of the IIIrd ventricle
  • Histological resemblance to atypical pineal teratoma
• Clinical Features:
  • Visual loss:
    • Chiasmatic pattern
    • May have concomitant anterior pathway involvement
  • DI in 80% of patients
  • Partial hypopituitarism
  • Age of onset: first or second decade
  • Growth retardation
  • Male = female incidence
  • Insidious visual loss; occasionally rapid

Suprasellar Aneurysm

• General Features:
  • Supraclinoid carotid aneurysm
    • Greater than 25 mm (giant aneurysm)
    • Women in 5th to 6th decade
    • Compression of optic nerve and chiasm
• Clinical Features:
  • Severe visual loss of ipsilateral eye
  • Arise below the ipsilateral optic nerve (distorted); then symptoms begin contralaterally
  • Expand anteriorly and superiorly
  • Insidious long duration of visual loss; rarely a rapid visual decline
  • Rarely the chiasm is anteriorly fixed; defect then is one of a tract lesion

Multiple Sclerosis

• Much rarer to have a chiasmatic rather than anterior nerve lesion
• VF defects:
  • Junctional pattern (decreased acuity of the ipsilateral eye; temporal crescent contralaterally)
  • Bitemporal defects

Arachnoidal and Epithelial Cysts

• General Features:
  • Serous cavity lined by neuroepithelium
  • Suprasellar cysts may arise in the floor of the IIIrd ventricle
  • Cysts of the sella turcica:
    • Cysts of Rathke's pouch
    • Epithelial cysts
    • Colloid cysts
• Clinical Features:
  • May extend into the chiasmatic cistern
  • Chiasmatic VF deficits
  • Pituitary dysfunction

Arachnoidal cysts

• General Features:
  • 70% base of the skull
  • Temporal fossa 29% > posterior fossa 21% > parasellar region 18%
• Clinical Features (when symptomatic):
  • Headache (50%)
  • Blurred vision (40%)
  • Seizures (40%)
  • Diplopia (15%)
  • Associated optic nerve sheath cysts (disc swelling)

Metastatic Disease of Optic Nerves and Chiasm

• Rapid unilateral or bilateral visual loss
• Usually without disc swelling
• Hematogenous spread; spread through CSF spaces
• Associated with rapid sequential multiple cranial nerve palsies
• Malignant lymphoma grows through the perivascular spaces; may have segmental demyelination
• Chronic lymphocytic leukemia (involves chiasm)
• Metastases to pituitary gland that secondary affect the chiasm as rare; may be associated with diabetes insipidus:
  • Seeding of posterior greater than anterior lobe
  • Diplopia may be associated

Sphenoidal Mucoceles

• Mucocele of posterior ethmoid and sphenoid paranasal sinus:
  • Clinical features:
    • Chronic headache
    • Varying ophthalmoplegia (involvement of the orbital apex)
    • Visual loss and VF defects
    • Involvement of chiasm (rare)

Trauma

• Visual loss after closed head trauma:
  • Neurapraxia, contusion or laceration of the optic nerve
  • Immediate visual loss
• Chiasmatic traumatic syndromes:
  • Much less common than optic nerve deficits
• Visual field deficits:
  • Complete monocular blindness with contralateral temporal deficits (junctional type)
  • Bitemporal arcuate scotomata
  • Transient diabetes insipidus
  • Anosmia: defects of II, IV, VII, VIII
  • CSF rhinorrhea; otorrhea
  • Carotid-cavernous fistula
  • Carotid pseudo aneurysm
  • Meningitis
• Mechanisms of chiasmatic injury:
  • Sagittal tearing (sphenoidal fracture)
  • Thrombosis or shearing of carotid artery blood supply to the chiasm
  • Contusion or hemorrhage of the chiasm itself

Complications of X-RT

• General Features:
  • Radiation necrosis occurs approximately 8–13 months after treatment
  • Radionecrosis of anterior visual system
• Clinical presentation:
  • Rapidly progressive visual loss in one eye
  • Decreased vision of second eye follows at short interval
  • Relentless progression to severe deficit
  • Visual field deficits:
    • Central scotoma or nerve fiber bundle defects
    • Chiasmatic defect
    • Optic tract defect
  • Chiasmatic defects associated with pituitary X-RT
  • Optic atrophy occurs two to three months after visual loss
  • Doses clearly associated with radionecrosis (5000 cGY); complications may occur with daily fractional doses of 200 to 220 cGY/treatment
  • Proliferative endarteritis of small blood vessels with secondary anoxia

Hydrocephalus

• General Features:
  • Pressure of the anterior aspect of the III ventricle (suprachiasmatic recess) on the chiasm (neurapraxia)
• Clinical presentation:
  • Bitemporal VF deficit
  • Progressive optic atrophy from pressure against bones of the sella or carotid artery

Pregnancy

• Increase of supra sella meningioma growth during the 2nd and 3rd trimester
• Optic neuritis more common after delivery
• Lymphocytic adenohypophysitis:
  • Occurs in a close time interval with pregnancy
  • Diffuse lymphocytic infiltration of the pituitary gland
  • Pituitary immune mediated
  • Exclusive to women

Empty Sella Syndrome

• General Features:
  • Extension of the subarachnoid space through the diaphragma sella
  • Defects in the diaphragma sella that are greater than 5 mm occur in 40% of patients
  • Normal volume of sella
  • Associations of empty sella:
    • Spontaneous
    • Arachnoidal cysts
    • Infarction of the pituitary gland
    • Pseudotumor cerebri
    • Pituitary surgery
    • X-RT
    • Pituitary apoplexy
• Clinical presentation:
  • Chiasmal herniation into the sella
  • Visual defects from adhesions of the optic nerves and chiasm (traction injury; diplopia and micropsia are rare complaints)
  • More frequent in obese women
  • 20–70 years of age (mean of 50 years)
  • Headache (usually frontal or bitemporal)
  • Occasional pituitary dysfunction (growth hormone, thyroid or luteinizing hormone; prolactin secretion)
  • Occasional CSF rhinorrhea
  • Blurring of vision, diplopia, micropsia a rare visual complaint

Miscellaneous Chiasmatic Process

• Devic's disease (MS)
• EBV infection
• Ethylchloranil (placid)
• Opticochiasmatic arachnoiditis:
  • Associated with meningovascular syphilis
  • Polyarteritis
  • Cystic adhesive fibrous arachnoidal thickening with lymphocytes
• Infectious meningitis:
  • Chiasmatic arachnoid inflammation (silent infection)
  • Cryptococcosis, pseudomonas aeruginosa, staphylococcus, streptococcus pneumonia; tuberculous meningitis; HIV, CMV of the optic nerve and chiasm; necrotizing angitis
• Sarcoidosis:
  • Involves posterior hypothalamus
  • Pituitary
  • Optic nerve sheaths
  • Chiasm involvement
  • Chiasmatic visual field loss