9.2. Trauma of the Lumbosacral Plexus
- Fracture:
- Double vertical fracture dislocations of the pelvic bony ring:
- 50% of patients suffer neurologic compromise
- Injury ipsilateral to iliac joint damage
- Lumbosacral plexus cord is the level affected with consequent compromise of L5, S1 innervated muscles
- Rupture, compression and traction injuries affect:
- Lumbosacral trunk:
- Primarily L5 (contribution of L4 root)
- Contiguous with all of the sacrum adjacent to the sacroiliac joint
- Obturator or superior gluteal nerves are injured
- L5–S3 anterior rami may be affected
- Concomitant vertebral body rupture
- Traction injury of the lumbosacral plexus:
- Fracture dislocation of the hip joint and acetabulum
- Severe deficits occur that are often permanent
- Intra-arterial injections:
- Injections into the buttock
- Ischemic injury due to vasoactive drugs that are injected into the inferior gluteal artery causing ischemia of the sciatic nerve
- Weakness, pain, and sensory loss in sciatic distribution may occur minutes to a few hours after the injury
- Widespread lumbar plexus injury may occur due to the retrograde extension of gluteal artery spasm to branches of the internal iliac artery
- Buttock skin may be painfully swollen, cyanotic, and develop gangrene
- Painless lumbosacral plexopathy may follow cisplatin or fluorouracil injection into the iliac artery
- Obstetric and gynecologic procedures that damage the lumbosacral plexus
- General Features:
- Risk factors:
- Short women with large babies
- Primigravida
- Post-partum weakness:
- Lumbosacral trunk (primarily L5 root) compression at the pelvic brim over the sacroiliac joint:
- Cephalic pelvic disproportion
- Protracted labor
- Midpelvic forceps delivery
- Weakness of the anterior tibialis, extensor hallucis longus, and everters with foot drop sensory loss in the lateral lower leg and dorsum of the foot
- Foot drop occurs on the side compressed by infant's brow in an occiput anterior presentation
- Involvement of the quadriceps muscle:
- Bilateral in 25% of patients
- Associated obturator neuropathy
- Causes of peripheral femoral neuropathy:
- Lithotomy position under anesthesia during vaginal delivery (compression under the inguinal ligament)
- Separation of symphysis pubis with direct compression of the nerve by the fetal head
- Epidural anesthesia
- Paracervical block affecting the posterior femoral nerve (pain may be delayed by several days)
- Lumbosacral plexus compressed at the pelvic brim by uterine leiomyoma (accelerated growth during pregnancy)
- Intrapelvic Schwannoma
- Catamenial sciatic nerve pain:
- Implantation of endometrium either intra abdominally or at the sciatic notch
- Endometrial deposits in the sciatic notch may be associated with an outpouching of a pocket of peritoneum
- Peri menstrual pain in the buttock or posterior thigh
Surgical Trauma of the Lumbosacral Plexus
- Laterally placed retractor blades compress the femoral nerve between the iliacus and psoas muscles:
- Abdominal hysterectomy
- Renal transplantation
- Lumbosacral plexus, sciatic and femoral neuropathy occur after:
- Vaginal hysterectomy
- Modified lithotomy position (under anesthesia)
- Pelvic procedures (ovarian tumors and cysts)
- Neuropraxic lesions:
- Stretch of the nerves and roots
- Angulation of the nerves by hyperabduction of the thighs under anesthesia
- Hip joint replacement
- 0.7–1% of hip replacement surgeries complicated by femoral, obturator or sciatic palsies
- Subclinical nerve damage occurs in a large number of hip replacements from:
- Preoperative stretch injury due to hip dislocation
- Hemorrhage
- Heat
- Toxicity from methylmethacrylate bone cement
- Direct trauma and that from retractor blades
- Post-operative aneurysm formation
- Aneurysm of the iliac or hypogastric artery:
- Rectal exam reveals firm pulsatile mass
- Surgical repair has been associated with ischemic plexus lesions
- Hemorrhage from aneurysm may compress the femoral nerve
- Sciatic nerve pain
- Retroperitoneal hematoma from abdominal aortic aneurysm leakage
- Rare severe stenosis of the abdominal aorta is associated with L5 symptomatology
|