Charcot-Marie-Tooth disease (CMT) is a common inherited neuromuscular disorder with a prevalence in the United States of 1 in 2,500 persons. CMT is subcategorized into seven main disorders based on the affected gene(s), clinical presentation, and projected severity of the disease.
Pathology: All forms of CMT result in some form of progressive peripheral muscle and sensory neuropathy from defective myelination. Over eighty genes have been associated with CMT. The main pathology of CMT results from defective genes for myelin production, function, and/or maintenance. CMT results in progressive slowing of nerve conduction to muscles and slowing of conduction from proprioceptive nerve bundles in the lower extremity. Patients often maintain temperature and pain sensitivity due to the unmyelinated slow C type nerve fibers that conduct these signals. The reduced proprioceptive and motor nerve function often results in visible musculoskeletal changes to the feet and lower legs. Chronic contractures of intrinsic foot and toe muscles, the lumbricles and plantar fascia will produce pes cavus and multiple hammer toes. Gradual shortening of the Achilles tendon will force the foot to be maintained in plantar flexion at rest and throughout the gait cycle. Loss of proprioception and motor control along with musculoskeletal deformities in the lower legs and feet predispose CMT patients to developing wounds either from acute trauma or gradually as a result of pathologic gait and body habitus.
Presentation: The age of clinical presentation of CMT ranges from childhood to the third decade. CMT can often go undiagnosed for years as the neuropathy and musculoskeletal deformities gradually manifest. The classic physical examination of a young adult with CMT will yield the following bilateral findings. Pes cavus (high longitudinal foot arch), diminished or absent deep tendon reflexes, decreased proprioception in the feet, and multiple hammer toes. Patients often present with a history of frequent falls, clumsiness, foot and lower leg pain, and/or leg muscle weakness.
Differential: One should be aware of other inherited neuropathies that have similar clinical presentations to CMT. Chiefly, Friedrich’s ataxia should be considered in the case of a child or adolescent presenting with bilateral pes cavus, hammer toes, and lower extremity peripheral neuropathy. Other pathology which can present similarly to CMT should also be considered. Some examples are muscular dystrophy, cerebral palsy and improperly healed lower leg and foot fractures.
Diagnosis: While genetic testing can provide definitive diagnosis of CMT disease and allow for specific subcalssification; the diagnosis can often be made clinically. Nerve conduction studies should show markedly decreased proprioceptive and muscular conduction speeds. X-ray, CT and MRI scans will show nonspecific musculoskeletal manifestations resulting from the nerve defects.
Disease Management: There are currently no medications to reduce the manifestations of CMT. Orthotic devices and surgery to correct foot deformities are often required by adulthood. Starting regular lower extremity and foot stretching and exercise routines early is an important strategy to limit or delay the disease progression. Patients should be counseled on the importance of maintaining a healthy body weight and diet to avoid the additional comorbidities that occur with obesity and diabetes.
Special Considerations in Wound Care: The proper wound care plan for patients with CMT who present with foot or lower extremity wounds must allow for accommodations of their disease. Practitioners must understand the additional biomechanical stresses that patients with CMT are subjected to. It is important to observe the patient’s gait if at all possible to assess the severity of the disease. This information will aid you in determining which type of orthotic is most appropriate in each CMT patient. A proper understanding of the clinical presentation and challenges of CMT will allow practitioners to develop better offloading strategies and wound care plans for their patients who have this disease. Practitioners will also be better equipped to understand the risks their patients with CMT face for developing future injuries and wounds. Referral to physical therapy, occupational therapy and neurology can each educate the patient about their disease and aid them in developing strategies to maximize their mobility and prevent future wounds.
Contributing author: Benjamin Byerly OMS-3, Campbell University School of Osteopathic Medicine
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