Histology · Year 1 · from Histology
Case 1: Multiple Sclerosis
Clinical Image
Source: Radiopaedia - Multiple Sclerosis - CC BY-NC-SA 3.0
Case Presentation
A 28-year-old woman presents with a 3-day history of blurred vision and pain with eye movement in her right eye. Two years ago, she had an episode of numbness and tingling in her legs that resolved spontaneously over several weeks. Neurological examination reveals a right relative afferent pupillary defect, decreased visual acuity (20/100), and impaired color vision. Fundoscopy shows mild optic disc swelling. MRI of the brain reveals multiple T2-hyperintense lesions in periventricular white matter with a characteristic "Dawson fingers" pattern (ovoid lesions perpendicular to the ventricles along the path of perivenular veins). Several lesions enhance with gadolinium, indicating active inflammation. MRI of the spine shows a demyelinating lesion in the cervical cord. Cerebrospinal fluid analysis reveals oligoclonal bands. She is diagnosed with relapsing-remitting multiple sclerosis. The pathophysiology involves autoimmune attack on oligodendrocytes and myelin in the CNS. Oligodendrocytes, each of which myelinates segments of up to 50 different axons, are destroyed, leading to demyelinated plaques and impaired saltatory conduction. She is treated with high-dose IV corticosteroids and started on disease-modifying therapy.
Key Learning Points
- Multiple sclerosis is an autoimmune inflammatory disease targeting oligodendrocytes and CNS myelin
- Oligodendrocytes each myelinate segments of multiple axons; their destruction produces widespread demyelination
- Loss of myelin disrupts saltatory conduction, slowing or blocking nerve impulse transmission
- CNS myelin has very limited regenerative capacity, so disability accumulates over time
- Understanding oligodendrocyte function (myelination of multiple axon segments) explains why focal inflammation produces widespread effects