The natural history of CMT 1A in adults: a 5-year follow-up

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Brain. 2009 Dec;132(Pt 12):3252-62.

The natural history of Charcot-Marie-Tooth type 1A in adults: a 5-year follow-up

study.

Verhamme C, van Schaik IN, Koelman JH, de Haan RJ, de Visser M.

Department of Neurology and Clinical Neurophysiology, H2-222, Academic Medical

Centre, University of Amsterdam, PO box 22660, 1100 DD Amsterdam, The

Netherlands.

Charcot-Marie-Tooth type 1A is the most prevalent hereditary demyelinating

polyneuropathy. The aim of this study was to investigate the natural history of

the disease in adults during a 5-year follow-up and to compare the changes over

time with those found in normal ageing.

In a cohort of 46 adult Charcot-Marie-Tooth type 1A patients, impairments and

physical disability were scored at baseline and at 1, 3 and 5 years.

Standardized nerve conduction studies and electromyography were performed at

baseline and at 5 years. Twenty-six healthy age- and sex-matched controls were

evaluated at baseline and at 5 years. Forty-four of 46 Charcot-Marie-Tooth type

1A patients (range 17-69 years) and 26 controls (range 25-65 years) completed

the 5-year follow-up.

The decrease in muscle strength and in compound muscle action potential

amplitudes was similar for patients and controls alike. However, in contrast to

the control group, physical disability increased over time in the patient group.

In patients, muscle strength and physical disability after 5 years were closely

related to these parameters at baseline. None of the other assessed baseline

characteristics, i.e. age, gender, compound muscle action potential amplitude

and motor nerve conduction velocity, predicted the extent of deterioration of

muscle strength or physical disability.

In adult Charcot-Marie-Tooth type 1A patients, the decline in axonal function

and in muscle strength may reflect, to a considerable extent, a process of

normal ageing. The slow increase in physical disability in adulthood may well be

explained by decreased reserves and compensatory mechanisms together with

progression of skeletal deformations due to muscle weakness.