Charcot-Marie-Tooth Disease (Type 1)

There are several forms of hereditary motor-sensory neuropathy (HMSN). What they have in common is that they are genetically transmitted and are characterised by a slow, progressive process of degeneration of the peripheral motor nerves and spinocerebellar tracts. There are two difference categories: the demyelinating forms and the neuronal forms. The demyelinating forms involve degeneration of the posterior columns and spinocerebellar tracts as well as loss of anterior horn cells. It is characterised by slow nerve conduction and hypertrophic changes to the nerves. The neuronal form involves degeneration of the axons of peripheral nerve cells. Together, these disorders affect approximately 1 in 2500 people.

Charcot-Marie-Tooth Disease (type 1) is also referred to as “peroneal muscular atrophy”. It is important not to confuse this condition with another condition with a similar name, namely “Charcot Foot”, which is a complication of diabetic peripheral neuropathy. Charcot-Marie-Tooth Disease (type 1) belongs to the category of demyelinating HMSN. A gene mutation on the chromosome 17 that codes for peripheral myelin protein-22 leads to the laying down of unstable myelin on peripheral nerves. This unstable myelin breaks down, resulting in segments of the peripheral nerve not being able to conduct impulses effectively. Schwann cells will attempt to repair these segments, laying down defective myelin, which also breaks down, leading to a vicious cycle and hypertrophy of the peripheral nerve, which begins to resemble an onion bulb.

This condition usually starts between the ages of 5 and 15. The child will present with difficulty walking, muscle cramps, and parasthesia (“pins and needles”) in the legs. As the disease progresses, there will be reduced function in the muscles of the lower leg, especially the peroneal muscles and the intrinsic muscles of the foot, leading to a “pes cavus” foot type, clawed toes, and muscle wasting, leading ultimately to a thin lower leg and a thicker thigh, rather unfortunately described as resembling “an inverted champagne bottle”. Sensory nerves are also affected leading to sensory neuropathy and loss of sensation. Tendon reflexes will be reduced or absent. There may also be twitching of the wasting muscles as flaccidity develops. Diagnosis is made by a positive family history of the disease as well as weakness and atrophy of the peroneal muscles.

Sadly, there is no effective treatment to prevent the demyelination process. Podiatrists can offer support (literally) through the prescription and fitting of bespoke in-shoe orthoses or splinting devices to offload high pressure areas, provide additional cushioning and redistribution of pressures, as well as perhaps helping to improve and stabilise gait. A podiatrist can also offer callus debridement and corn enucleation as well as wound care if required.

In advanced cases, surgery may be recommended to immobilise joints.

%d bloggers like this: