CHARCOT-MARIE-TOOTH

Weird foot disease

Charcot-Marie-Tooth Disease is a genetic demyelinating disorder. It is autosomal dominant. CMT classically impacts the Common Fibular Nerve, causing foot drop and foot deformities. The arms will be involved later on. 

Are there any helpful identifying characteristics?

Yep, there’s a histology buzz word: onion bulbs. If you examine the axons under a microscope, you might observe axons that are extra thiqq because they have more myelin layers than usual. Here’s why it happens. CMT damages Schwann cells and myelin. The body tries to repair that damage. Instead of cleaning up the old myelin, it just rolls new myelin on top of the old,  creating the extra bulky myelin sheaths. See pic below. 

What are the symptoms?

Flaccid leg weakness (foot drop), foot deformities (hammer toe, pes cavus), hyporeflexia and loss of fine touch and proprioception. The perception of pain is spared because this is a demyelinating disease, and nociceptors don’t have myelin.