CMT 1A: progression in duplication: clinico-electrophysiological and MRI longitu

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J Neurol. 2010 May 5.

Clinical progression in Charcot-Marie-Tooth disease type 1A duplication:

clinico-electrophysiological and MRI longitudinal study of a family.

Berciano J, Gallardo E, García A, Ramón C, Infante J, Combarros O.

Service of Neurology, University Hospital Marqués de Valdecilla (IFIMAV),

University of Cantabria and Centro de Investigación Biomédica en Red de

Enfermedades Neurodegenerativas (CIBERNED), 39008, Santander, Spain

Abstract

Long-term follow-up studies in Charcot-Marie-Tooth disease type 1 duplication

(CMT1A) are scanty. Here we describe a longitudinal study in a CMT1A pedigree.

Our CMT1A pedigree comprised 11 examined patients, ages between 13 and 83

(median, 36) years, serially evaluated for up to 26 years.

In all 11 patients we carried out electrophysiological evaluation, and in three

of them magnetic resonance imaging (MRI) of lower-limb musculature. The

54-year-old proband patient, yearly examined as of age 28, developed at age 48

gradual and progressive distal lower-leg weakness ascending to thigh

musculature.

His serial electrophysiological studies showed diffuse slowing of motor

conduction velocity, absence or severe attenuation of distal compound muscle

action potentials, and spontaneous muscle activity in the tibialis anterior and

rectus femoris.

Two MRI studies of lower limbs, at ages 51 and 54, showed extensive fatty

atrophy of lower-leg musculature, and progressive and distally accentuated fatty

atrophy of anterior and posterior femoral muscles. An outstanding finding in the

first MRI was the presence of marked edema of anterior femoral musculature,

which to a great degree was replaced by fatty atrophy in the second study.

Muscle edema was also noted in lower-leg and posterior femoral musculature.

There was minimal fatty atrophy of the gluteus maximus, the remaining pelvic

muscles being preserved. The other ten patients showed mild or moderate

phenotype, which remained quiescent over the period of observation.

Electrophysiological studies disclosed diffuse and uniform slowing of nerve

conduction velocities; in no case was spontaneous muscle activity recorded.

MRI showed the CMT1A characteristic pattern of distally accentuated fatty

atrophy involving foot and lower-leg musculature with preservation of thigh

musculature.

We conclude that a small proportion of patients with CMT1A develop a late

progression of disease manifested with accentuated distal leg weakness ascending

to involve thigh musculature, and that long-term follow-up is essential for its

detection.