Charcot-Marie-Tooth Disease (CMT)

Charcot-Marie-Tooth Disease (CMT)

Charcot-Marie-Tooth disease refers to a group of hereditary (mainly) disorders affecting the peripheral nerves, ie nerves outside the brain and spinal cord. There are different types of CMT and each one is caused by a different mutation and new causes are constantly discovered. Essentially, it is one of the types of neuropathy. It affects 2.8 million people worldwide, regardless of race and nationality.

There are several types of inheritance, mainly autosomal dominant  [CMT1A-CMT1F/2E (50-80%), CMT2A-2U (10-15%)], the intermediate types with myelinopathy and axonal degradation [DI-CMTA – DI-CMTF], but there are some recessive types [rarest cases of CMT4A – CMT4J, CMT2BI and CMT2B2] and X-linked types [CMTX1-CMTX6 (10-15%)]. Mutations may also be de novo, although there is no family history or none of the parents is a carrier.

Symptoms

Some types of CMT destroy the outer layer of nerve fibers (myelin), while others destroy the nerve fibers themselves. Initially, the damage starts from the longest nerve fibers of the lower and upper limbs. Motion and aesthetic fibers (responsive to sensation) are impaired, causing weakness and numbness, starting from the feet. Symptoms in most cases start earlier than the age of 20 years.

Usually they include:

  • Foot deformations (large “arch”),
  • Weakness of horizontal tread position,
  • Progressive foot deformity,
  • Loss of muscle function low in legs and weak legs,
  • Numbness in lower limbs,
  • Difficulty of balance,
  • Similar hand symptoms as the disease progresses,
  • Scoliosis or kyphosis (in some cases).
  • In several case severe breathing problems are reported, such as apnea and larynx neuropathy, dysphagia, urinary and boewl problems, and in some cases ocular neuropathy.

Brain function is not affected.

Diagnosis

It is performed with full neurological assessment by a neuromuscular specialist and includes personal and family history, clinical exams, nerve conduction tests, electromyography, (rarely) muscle biopsy, and appropriate genetic tests to determine the exact type of mutation to follow genetic counseling.

Prognosis – Progression

CMT has a slow progression and deterioration. It rarely evolves rapidly and measures and reassessment must be taken. Problems of numbness, weakness, difficulty in balance and orthopaedic problems can evolve and cause disability in some cases. Pain is another serious problem, which can be due to either neuropathy or orthopaedic problems.

Possible complications are:

  • Progressive inability of walking,
  • Progressive inability of using hands,
  • Injuries in areas with reduced sensation.

Management

So far, there are no drugs to either cure or slow the progression of the disease. However, research efforts are being undertaken worldwide for many of the CMT types.

Physiotherapy, occupational therapy, hydrotherapy, speech therapy and physical activities can contribute to maintaining muscle strength and independence.

In particular, physiotherapy should include stretching exercises, posture and balance stability, and of course strategies to avoid falls and any complications, techniques for energy backups, use of night splints. There are some researches showing that the use of bicycles can also contribute to the mobility maintenance.

Occupational therapy contributes to the empowerment of hands and wrists or avoidance of deterioration, in combination with assistive devices.

Orthotics (AFOs) devices, splints or shoes can facilitate gait.

Orthopaedic lower leg surgery can often maintain or correct leg function to facilitate walking. Particular attention is required for those patients who feel numbness in the legs and they need special care with good washing, drying and frequent overview of any minor ulcers. Of course, annual examination by a neurologist or pediatrician is recommended and contributes to avoiding complications.

To be more specific, neurologist provides regular assessments for many years, diagnosis, and assesses any deterioration, as well as recommendations for all the appropriate changes of daily life. Assessments of urologists, ophthalmogists and gastrointestinal specialists are also recommended.

Moreover, use of BiPAP may be critical when there are breathing complications.

Genetic counseling is in order for the possibility of CMT in the next generations. Finally, except for the regular contact, collaboration and assessment of the orthopedic surgeon, physical therapist and occupational therapist, it is important to contact with a psychologist or a psychiatrist to cope with stress, depression and potential physical alterations due to the disease.

 

Detailed CMT management:

Management of CharcotMarieTooth disease improving long-term care with a multidisciplinary approach

 

Information about clinical trials conducted globally: https://www.centerwatch.com/clinical-trials/listings/condition/709/peripheral-neuropathy/ and https://clinicaltrials.gov/ct2/home

 

References

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