Charcot-Marie-Tooth (CMT) disease is an inherited disorder of the peripheral nerves. CMT and other inherited disorders are due to defects of genes for various proteins in the nerve fibers. The inheritance pattern in these disorders can be autosomal dominant, autosomal recessive or X-linked. Although the genetic defect is present at the time of conception, the onset of symptoms varies with the type of inherited neuropathy. In some patients, the symptoms are present at birth or develop soon after birth. In other patients, the disease may manifest itself later in life. Other common inherited neuropathies include Dejerine-Sottas disease and Friedrich’s ataxia.
The symptoms of inherited neuropathies depend on the type of neuropathy. Most patients experience very slowly progressive sensory symptoms that start in the feet and move up. They also have atrophy and weakness in their legs and, later in life, in their hands. The ankle weakness often leads to ‘foot drop’. Some patients experience balance problems. Patients, with involvement of the autonomic system, experience lightheadedness, diarrhea, constipation, incontinence or sexual dysfunction.
Diagnosis of inherited neuropathies is based on history, clinical examination and supporting laboratory investigations. These include electromyography with nerve conduction studies, skin biopsies to evaluate cutaneous nerve innervation, and nerve and muscle biopsies for histopathological evaluation. Genetic testing is available in some of the inherited neuropathies and can be done through a blood test.
Treatment of CMT and other inherited neuropathies is accomplished through a multidisciplinary team of physicians, physiatrists, genetics counselors, and physical and occupational therapists. Patients with weakness may benefit from splints, orthotics and walking aids. Patients that experience neuropathic pain can be treated with anti-seizure medications, antidepressants, or analgesics.