What is the epidemiology of lumbosacral plexopathy?

Epidemiology of Lumbosacral Plexopathy

Lumbosacral plexopathy is a relatively rare clinical condition with multiple etiologies, primarily including neoplastic, inflammatory, and immune-mediated processes affecting the nerve network formed by spinal nerves L1-S4. 1, 2

Etiologies and Prevalence

Neoplastic Causes

• Primary tumors of the lumbosacral plexus are most commonly benign peripheral nerve sheath tumors (schwannomas and neurofibromas) 1, 2
• Malignant peripheral nerve sheath tumors are rare and occur more frequently in patients with neurofibromatosis 1
• Other primary malignant or metastatic tumors can also involve the lumbosacral plexus 1
• Plexopathy can be the first clinical presentation of neoplastic disease 1

Non-neoplastic Mass Lesions

• Hematoma, abscess, aneurysm, amyloidosis, and endometriosis can involve the lumbosacral plexus 1, 2
• These represent important non-malignant causes of compressive plexopathy 1

Inflammatory and Immune-Mediated Causes

• Diabetic amyotrophy (Bruns-Garland syndrome) is a well-recognized cause of lumbosacral plexopathy 3, 4
• Acute inflammatory demyelinating polyneuropathy (Guillain-Barré syndrome) can present with lumbosacral plexopathy 1, 2
• Chronic inflammatory demyelinating polyneuropathy (CIDP) may affect the lumbosacral plexus 1, 2
• Idiopathic lumbosacral plexopathy (also called lumbosacral plexitis or non-diabetic lumbosacral radiculoplexus neuropathy) is a rare clinical entity with suspected immune-mediated etiology 5, 6
• Sarcoidosis can involve the lumbosacral plexus 1, 2
• Zoster-associated limb paresis can affect the plexus 1, 2

Other Causes

• Entrapment neuropathies are common causes resulting from spinal or extraspinal compression 2
• Piriformis syndrome is a frequently described cause of extraspinal nerve entrapment 2
• Ischemic nerve injury can lead to lumbosacral plexopathy 2
• Hereditary neuropathies (e.g., Charcot-Marie-Tooth disease) may present with plexopathy 2

Clinical Course and Prognosis

• Idiopathic lumbosacral plexopathy generally runs a monophasic and self-limiting course 5
• Recovery is typically slow, ranging from 6 to 36 months, and is often incomplete 3
• In diabetic and non-diabetic forms, the condition is usually monophasic and preceded by significant weight loss (at least more than 10 lbs) 4
• Some evidence suggests that early immunosuppressive treatment (within three months of symptom onset) may hasten recovery in cases with suspected inflammatory etiology 4

Diagnostic Challenges

• The clinical diagnosis of plexopathy can be challenging due to considerable overlap with radiculopathy symptoms 1, 7
• Lumbosacral plexopathy is often misdiagnosed initially due to its rarity and complex presentation 8
• Electrodiagnostic studies are essential for confirming plexopathy and distinguishing it from other conditions 8
• MRI of the lumbosacral plexus is the preferred imaging modality for evaluation due to its superior soft-tissue contrast and spatial resolution 1

Common Pitfalls in Diagnosis

• Failure to distinguish between plexopathies and radiculopathies, which typically follow a single dermatome distribution 2
• Not recognizing that lateral disc herniations may cause plexopathy that is not detected on standard lumbar spine MRI 2
• Overlooking the need for dedicated lumbosacral plexus imaging protocols that differ from routine spine or pelvic MRI 1