Neuro Diseases: Charcoat Marie Tooth Neuropathy

Charcoat Marie Tooth Neuropathy (CMT) is a type of hereditary motor sensory neuropathy (HMSN). It is the commonest type of inherited neuropathies in human beings.

There are a number of HMSNs and CMT is one among them. Even CMT is not actually one single disease; there are many subtypes. They are all hereditary (genetic) in nature. CMT type 1 is the commonest. Generally the motor fibers of the nerves are more prominently involved that is why it is called as HMSN.

CMT is also called peroneal muscular atrophy because of the prominent weakness and thinning peroneal muscles by this nerve damage.

HMSN are characteristically chronic illnesses, the onset of neuropathy is very gradual as well as its progression, however few subtypes like Dejerine Sottas progresses rapidly. They generally present at a younger age but some of them may present later in life.

Sensory symptoms like tingling, numbness are present but not necessarily that prominent. It is the slowly progressive muscle weakness and atrophy (thinning) that is what is typical for these diseases. The weakness and atrophy of muscles starts in the distal areas like feet and hands then extends proximally. Legs are affected first then arms, and this is typical for majority of the chronic peripheral neuropathies.

Foot drop is a common manifestation. Pes cavus (exaggerated concavity of the arch of foot), hammer toes (clawing) are seen in majority of these cases.

Involvement of the face, bulbar muscles (muscles in the throat area), bowel and bladder is not common for these diseases.

They are genetically mediated and caused by genetic mutations. AD (Autosomal dominant), AR (Autosomal recessive), and X linked types of inheritances are all seen. Majority of these neuropathies are primarily demyelinating type but there are few primarily axonal types too.

The following neurology tests are usually employed to arrive at the diagnosis;

• EMG/NCS (electromyography & nerve conduction study)
• Nerve Biopsy
• Genetic studies
• Blood tests etc

In a typical case too many neuropathy blood tests like B12, thyroid, vasculitis work up (ESR, CRP, ANA etc), HIV etc are not required, but in borderline cases such tests may be necessary.

Majority of these neuropathies are typically demyelinating type and show uniform demyelization on EMG test unlike the acquired demyelinating neuropathies like Guillain Barre Syndrome (acquired inflammatory demyelinating polyradiculoneuropathy) or CIDP (chronic inflammatory demyelinating polyradiculoneuropathy) where segmental demyelination is seen.

At this moment there is no curative treatment for these neuropathies. Management is only supportive & symptomatic. PT (physical therapy), OT (occupational therapy), treatment for the pain, numbness, tingling sensation (pins and needles) etc are the mainstays of the management.

There are several drugs that are supposed to be avoided by CMT patients (e.g. vincristine, cisplatin etc)

Assistive devices, orthopedic surgery etc are needed to manage the limb deformities.

A Neurologist, neurosurgeon and orthopedic surgeons are frequently involved in the care of Charcoat Marie Tooth Neuropathy patients.