CMT 1A: Lower limb manual muscle testing in the early stages

October 20, 2006

Funct Neurol. 2006 Jul-Sep;21(3):159-63.

Lower limb manual muscle testing in the early stages of Charcot-

Marie-Tooth disease type 1A.

Vinci P, Serrao M, Pierelli F, Sandrini G, Santilli V.

Charcot-Marie-Tooth disease (CMT) is a genetically and clinically

heterogeneous disorder that affects approximately one in 2,500

individuals. CMT 1A, which is due to a duplication in the area

containing the PMP-22 gene on chromosome 17, is the most frequent

CMT subtype.

To date, there is no consensus among authors about which muscles are

weakened in the early stages of CMT, even though this knowledge

would be crucial for deciding the most appropriate interventions to

restore balance between muscles and prevent the development of

deformities.

The aim of this study was to evaluate the strength of several lower

limb muscles in the early stages of CMT 1A.

In a series of 45 patients (age 10-72 years; 21 males, 24 females)

affected by CMT 1A, we evaluated 83 non-operated lower limbs that

corresponded to the two milder stages of a five-level functional

classification. The strength of two foot muscles, seven leg muscles,

two thigh muscles, and three pelvic girdle muscles was graded using

the manual muscle testing techniques of s and Worthingham; the

power of the triceps surae was graded, in the prone position, using

a 4-level scale of ability to raise the heel from the floor.

Muscle strength was determined on the basis of interobserver

agreement estimated by kappa statistics between two observers. The

flexor hallucis brevis and lumbricals were very weak in all the

limbs; the leg muscles were strong in more than 90% of limbs, except

the peronei (strong in 83.13%); all the triceps surae were strong in

the prone test, but 16.87% were weak in the standing test; all the

proximal muscles were strong.

In the large majority of patients in the early stages of CMT 1A, the

intrinsic foot muscles are very weak and the leg and proximal

muscles are strong.

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