Exploring Charcot Marie Tooth Disease

Introduction

As your time in clinical practice grows, you will inevitably encounter a wide range of compromised health conditions among your clients. Although some cases—such as tendinosis or carpal tunnel syndrome—may be exactly what they appear, it is crucial not to assume that familiar symptoms always indicate a common condition. Systemic nerve disorders, in particular, often mimic local nerve compression syndromes, leading to potential misdiagnosis if clinicians are not alert to the differences.

Charcot-Marie-Tooth (CMT) disease is a prime example of a systemic condition that can masquerade as one or multiple local nerve compression pathologies. Despite sounding like a dental issue, CMT is a hereditary neurological disorder named after Jean-Martin Charcot, Pierre Marie, and Howard Tooth, who first described it in 1886. Unlike common mechanical nerve compression injuries, CMT stems from genetic mutations and not overuse. Although the disorder is genetically inherited, it sometimes skips generations. Affecting approximately 125,000 people in the United States, CMT occurs with a frequency comparable to multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS), but receives less attention because it is not life-threatening.¹

CMT also goes by other names, including hereditary motor and sensory neuropathy and peroneal muscle atrophy. However, the term peroneal muscle atrophy can be misleading. Many descriptions associate CMT with a drop-foot gait, attributing it to peroneal muscle atrophy. However, the primary peroneal muscles (peroneus longus and brevis) are plantar flexors, not dorsiflexors. Therefore, weakness in these muscles does not cause drop-foot gait. Instead, drop foot results from inadequate nerve supply to the foot’s dorsiflexor muscles.

Types of Charcot-Marie-Tooth Disease

CMT is traditionally categorized into two primary types, although modern research continues to refine these classifications into further subtypes. Type 1 CMT is a demyelinating neuropathy that disrupts the myelin sheath covering peripheral nerve fibers. The myelin sheath plays a vital role in ensuring proper nerve signal transmission (Figure 1). In Type 1, a genetic mutation causes the myelin sheath to become unstable and spontaneously degrade, severely impairing signal conduction.

Figure 1
The myelin sheath of a typical nerve
Image courtesy of Wikipedia

Type 2 CMT, by contrast, involves wallerian degeneration, a process that affects both the myelin sheath and the axonal continuity of the nerve fiber. This leads to degeneration that is not limited to the nerve’s insulating layer but also disrupts the inner core of the nerve itself. Distinguishing between Type 1 and Type 2 CMT requires specialized laboratory testing, as clinical presentation alone often provides insufficient differentiation.

Evaluation and Treatment

Evaluating CMT can be challenging because its symptoms closely resemble those of other peripheral nerve disorders. Symptoms often appear first in the distal lower extremities, with notable involvement of muscles innervated by the deep and superficial peroneal nerves. In CMT, motor dysfunction—including muscle weakness and coordination difficulties—is far more pronounced than sensory disturbances such as numbness or paresthesia. However, these motor-focused symptoms can also resemble those seen in compression neuropathies, such as common peroneal nerve entrapment.

Clients with CMT frequently present with foot drop due to impaired dorsiflexor function. Symptoms typically begin during adolescence—the second decade of life—but may initially be mistaken for normal clumsiness associated with growth spurts. As the client ages, the progressive nature of motor nerve damage leads to worsening functional impairment.

Clinicians should be alert to the development of pes cavus (an excessively high arch, shown in Figure 2) and hammer toes. Leg observation often reveals “stork-like” appearance due to significant muscle atrophy. Clients may demonstrate the ability to walk on tiptoes—utilizing the plantar flexors—yet struggle significantly with heel walking, which depends on the weakened dorsiflexors.

Figure 2
The pes cavus foot that is common in CMT disease
Image courtesy of Wikipedia

A comprehensive health history is critical during evaluation. Certain medications and even excessive vitamin intake can aggravate CMT symptoms, so gathering detailed information about pharmaceutical and supplement use is essential.¹

Although CMT primarily affects the lower extremities, upper extremity involvement can also occur. Clients with hand involvement typically report difficulty with fine motor tasks, such as operating zippers or fastening buttons, again highlighting the motor-dominant nature of the pathology.

Clinical Management Considerations

Currently, no cure exists for CMT, so management focuses on stabilizing symptoms and preserving function. Conservative interventions, including physical therapy and orthotic devices, aim to support lower extremity function. In cases where structural deformities such as severe pes cavus arise, surgical interventions may be considered. However, because nerve degeneration is progressive, surgical outcomes may be temporary or limited in effectiveness. As motor control continues to deteriorate post-surgery, previously corrected foot alignment may once again become compromised.

Massage therapy does not offer a corrective solution for CMT, but it may help alleviate secondary issues related to the condition, such as soft-tissue discomfort. Importantly, while massage is not harmful to clients with CMT, it is essential for therapists to recognize when symptoms suggest a systemic neurological problem rather than a local compression issue. Identifying signs of a systemic pathology ensures that clients are referred promptly to a physician for appropriate diagnosis and management.

Resources

1. Stadler T, Ross D. Charcot-Marie-Tooth Disease in a High School Tennis Player. Phys Sportsmed. 2002;30(10).