Скачать или смотреть segmental demyelination; loss or damage of myelin sheath protective covering nerve fibers

Segmental demyelination is a pathological process where myelin sheaths—the protective covering around nerve fibers—are damaged in discrete segments, while the underlying axon remains initially intact. This disrupts the transmission of electrical impulses along the nerve, leading to neurological symptoms.

🧠 What Happens in Segmental Demyelination?
Myelin loss occurs in patches along the nerve fiber.

The axon itself is preserved early on, but prolonged demyelination can lead to axonal degeneration.

Remyelination may occur, but the new myelin is often thinner and less effective.

In severe cases, structures called "onion bulbs" may form—layers of Schwann cells and connective tissue around the axon, indicating repeated cycles of demyelination and repair.

🩺 Causes
Segmental demyelination is commonly seen in peripheral neuropathies, especially:

Guillain-Barré Syndrome (GBS)

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)

Toxin exposure (e.g., heavy metals, certain medications)

Inherited disorders like Charcot-Marie-Tooth disease

🔍 Diagnosis
Nerve conduction studies show slowed signal transmission.

Teased fiber preparations and electron microscopy can visualize demyelinated segments and onion bulbs.

💊 Treatment
Depends on the underlying cause.

Immunosuppressive therapy for autoimmune conditions.

Plasma exchange or IVIG for GBS and CIDP.
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