Histology · Year 1 · from Histology
Case 3: Guillain-Barre Syndrome
Clinical Image
Source: Wikipedia - Guillain-Barre Syndrome - CC BY-SA 3.0
Case Presentation
A 45-year-old man presents with rapidly progressive weakness that began in his feet 4 days ago and has now ascended to involve his thighs. He had a diarrheal illness 2 weeks prior. Neurological examination reveals symmetric, flaccid weakness more prominent distally, absent deep tendon reflexes (areflexia), and mild sensory loss in a stocking distribution. He has difficulty taking a deep breath (vital capacity 50% of predicted), indicating respiratory muscle involvement. Cerebrospinal fluid analysis shows albuminocytologic dissociation (elevated protein with normal cell count). Nerve conduction studies reveal severely reduced conduction velocities and conduction block, consistent with demyelination. He is diagnosed with Guillain-Barre syndrome (GBS), an acute inflammatory demyelinating polyneuropathy. The pathophysiology involves autoantibodies (often triggered by preceding infection with Campylobacter jejuni) attacking Schwann cells and peripheral myelin. Unlike MS affecting the CNS, GBS has a relatively good prognosis because Schwann cells can proliferate and remyelinate peripheral axons. He is treated with IV immunoglobulin and requires temporary mechanical ventilation. He recovers substantially over several months.
Key Learning Points
- GBS targets Schwann cells and peripheral myelin, in contrast to MS which targets oligodendrocytes and CNS myelin
- Each Schwann cell myelinates only one segment of one axon (unlike oligodendrocytes that myelinate multiple axons)
- The PNS has much greater regenerative capacity than the CNS because Schwann cells proliferate and form bands of Bungner to guide remyelination
- Schwann cells are surrounded by basal lamina; these basal lamina tubes persist after injury and guide regenerating axons and remyelinating Schwann cells
- Understanding the difference between CNS and PNS myelination explains the different prognoses of MS versus GBS
Summary: Glial Cell Disorders
These cases demonstrate how understanding glial cell biology informs clinical practice:
| Disorder | Glial Cell Affected | Location | Regenerative Capacity | Prognosis |
|---|---|---|---|---|
| Multiple Sclerosis | Oligodendrocytes | CNS | Very limited | Progressive disability |
| Glioblastoma | Astrocytes (neoplastic) | CNS | N/A (tumor) | Poor (median 15 months) |
| Guillain-Barre Syndrome | Schwann cells | PNS | Good (proliferate, remyelinate) | Generally good recovery |
The key distinction between CNS and PNS myelination - oligodendrocytes (multiple axon segments per cell, no basal lamina, limited regeneration) versus Schwann cells (one segment per cell, basal lamina present, robust regeneration) - explains critical differences in disease outcomes.