Differential Diagnosis in Neurology

16.10. Neoplasms Causing Dementia

• General considerations:
  • Occur with both malignant and benign tumors
  • Dementia determined primarily by site of the neoplasm
  • Slow growing tumors most frequently cause diagnostic confusion
• Clinical features:
  • Location:
    • Midline:
      • Colloid cysts
        • Severe positional headache
        • Obstructive hydrocephalus
      • Pinealoma:
        • Eye movement defects (failure of vertical gaze)
        • Hearing loss
        • Aqueductal stenosis with hydrocephalus
      • Pituitary tumors:
        • Panhypopituitarism
        • Chiasmatic visual defects
        • Hydrocephalus
        • Dementia from thyroid failure
      • Midline thalamic glioma:
        • Somnolence
        • Aphasia
        • Fluctuating levels of alertness

Frontal Lobe Neoplasms

Meningioma

• Subfrontal tumors
• Pressure and irritation of the limbic orbitofrontal cortex:
  • Seizures
  • Personality and behavioral change
  • Rarely Foster Kennedy syndrome
• Dorsolateral prefrontal cortex:
  • Frontal lobe syndrome:
    • Poor memory retrieval
    • Deficits of planning, execution and attention
  • Global decrease of cognitive function

Glioblastoma Multiforme

Bilateral involvement:

• Crosses to contralateral side through the corpus callosum
• Frontal lobe syndrome
• Seizures
• Abulia (subfrontal syndrome)

Gliomatosis Cerebri

• Malignant astrocytes around cerebral blood vessels
• Generalized cognitive decline

Lymphoma

• Primarily noted in AIDS patients
• Crosses the midline through the corpus callosum
• More necrotic on MRI than usual lymphoma
• Frontal lobe syndrome

Dementia with X-RT for Malignant Tumor

• General considerations:
  • 5000 rads for whole brain irradiation
• Clinical features:
  • Acutely:
    • Demyelination with edema
  • All neurological systems involved:
    • Cortex
    • Basal ganglia (subcortical dementia)
    • Cerebellar ataxia
    • Parkinsonism
  • Hypothyroidism and endocrine dysfunction if pituitary area has been irradiated
  • Chronic syndrome after one year:
    • Small vessel strokes (proliferative endarteritis)
    • Seizure activity

Large Areas of Necrosis (Occur After X-RT)

• General considerations:
  • Magnetic resonance spectroscopy (MRS) or PET determines if it is tumor recurrence or irradiation necrosis
    • PET-increased glucose utilization (tumor)
    • MRS-increased lactic acid resonance (tumor)
• Clinical features:
  • Large vessel accelerated atherosclerosis with stroke
  • Small vessel strokes

Paraneoplastic Syndromes with Dementia

• General considerations:
  • Primarily immune mediated:
    • Anti-Hu antibody (antinuclear)
    • Small cell carcinoma of the lung most frequent tumor, breast, GI, ovary and prostate are also common tumors
• Clinical features:
  • Limbic encephalitis
  • Bilateral involvement of the hippocampal formation; parahippocampal gyrus; cingulate gyrus
  • Memory impairment
  • Personality and behavioral change
  • Seizures
• Pathology (limbic encephalitis):
  • Neuronal loss:
    • Hippocampus
    • Cingulate gyrus
    • Lymphocytic perivascular cuffing
• Diagnostic evaluation:
  • Anti-Hu or other paraneoplastic antibodies Ma, Ta, Ri, CAR are positive
  • Increased lymphocytes and protein in CSF