CMT SYMPTOM PROGRESSION

Being aware of the progression CMT can have is an important aspect of living with and managing the disease.

CMT has numerous aspects that have to be considered when managing the disease. The severity of the disease can range from unnoticeable to severely limiting mobility and independent living. To add an additional layer of complexity on top of that, with the disease being degenerative, it is expected that symptoms become more severe over time, yet how quickly this occurs is not yet detectable until new symptoms, or worsening of existing ones, become more apparent.

CMT - A PERSONAL DISEASE

CMT can cause a variety of symptoms, usually first noticed during adolescence. How quickly or slowly these symptoms may progress, or what symptoms may occur, can not yet be predicted. Even between the same subtypes of CMT, the onset and severity of symptoms can vary radically. This can result in the symptoms of people with the same subtype of CMT being significantly different, ranging from asymptomatic to reliant on walking aids from a young age.  Unfortunately, there is a scarcity in research regarding the average rate of CMT progression across any of the CMT types, largely in part due to a lack of adequate and routine monitoring of patients and their symptoms.  Current research however does indicate that the rate of progression of CMT increases with age. Below is a general example of the progression of the disease in a person with CMT-1A, where diet, exercise and other external factors do not change the clinical situation and the person would be considered to have an "average" rate of progression for the disease with an initial CMT NS of <10.

Key Points
  • Symptoms of CMT-1A are present during the first decade of life in over 60% of cases [1].

  • Functional disability has found been found to increase with disease duration [2], although severity itself is not related to age and the extent of the disease progression after childhood is either minimal or not active [3].

  • The main identifiers for the disease are muscle weakness and slow nerve conduction. [4]

  • Disease progression is mixed: one study found symptoms to gradually worsen every 2-3 years, with a separate study finding that the decline in adulthood may, to a considerable extent, reflect a process of normal ageing rather than on-going active disease [3]

  • The CMT Neuropathy Score is used to identify disease severity. Due to the subjective nature of the tests, it has resulted in a lack of useful research with objective measurements from devices such as dynamometers being underutilised. 

  • A small proportion of patients with CMT-1A show signs of the disease later in life [5]

 

References (Click to expand)

  1. Harding AE, Thomas PK. The clinical features of hereditary motor and sensory neuropathy types I and II. Brain. 1980;103(2):259-280. doi:10.1093/brain/103.2.259

  2. Berciano J, García A, Combarros O. Initial semeiology in children with Charcot-Marie-Tooth disease 1A duplication. Muscle Nerve. 2003;27(1):34-39. doi:10.1002/mus.10299

  3. Hoogendijk JE, De Visser M, Bolhuis PA, Hart AA, Ongerboer de Visser BW. Hereditary motor and sensory neuropathy type I: clinical and neurographical features of the 17p duplication subtype. Muscle Nerve. 1994;17(1):85-90. doi:10.1002/mus.880170112

  4. Berciano J, Combarros O, Calleja J, Polo JM, Leno C. The application of nerve conduction and clinical studies to genetic counseling in hereditary motor and sensory neuropathy type I. Muscle Nerve. 1989;12(4):302-306. doi:10.1002/mus.880120408

  5. Berciano J, Gallardo E, García A, Ramón C, Infante J, Combarros O. Clinical progression in Charcot-Marie-Tooth disease type 1A duplication: clinico-electrophysiological and MRI longitudinal study of a family. J Neurol. 2010;257(10):1633-1641. doi:10.1007/s00415-010-5580-x

Initial Symptons of CMT (ages 0 - 17)
  • High arched feet

  • Tight Achilles tendon

  • Ankle weakness​

  • Loss of sensation in toes and/or feet.

 

Symptoms may be noticeably worse around growth spurts due to excessively tight lower limb muscles.

Onset of CMT (ages 18-30)
  • Minor muscle spasms in leg muscles become noticeable

  • Contractures based around the toes may begin

  • Muscle atrophy continues in the lower body

Progression of CMT (ages 31-50)
  • Contractures become more prominent

  • Other mechanical issues, such as bursas, may start to occur. These can be minimised or prevented by having adequate insoles to redistribute the weight of the feet accordingly 

  • Stress fractures in high arched feet may occur, varying in severity based on multiple factors, including the shape of the foot, weight of the person, level of activity they undertake on their feet and more

  • Muscle atrophy becomes more apparent in the lower limbs

  • Loss of strength in the hands may begin 

CMT in later life (ages 51+)
  • Neuropathic degradation resumes, resulting in potentially further loss of sensation in the feet and hands

  • Neuropathic pain may occur as the nerves continue to die, progressing more quickly than in previous years

  • Extensive muscle atrophy continues in lower limbs, potentially resulting in limited mobility

  • Severe muscle atrophy may extend to the hands