Neuromuscular function in limb girdle dystrophy.

Abstract

SUMMARY The contractile properties of ankle dorsiflexor and plantarflexor muscles in 20 patients with limb girdle muscular dystrophy have been compared with those in matched controls. Twitch and voluntary torques were significantly smaller in the patient population and in nine patients it was impossible to record a twitch from tibialis anterior, a dorsiflexor muscle studied in detail. The disease process evidently ran a more rapid course in tibialis anterior than in plantarflexor muscles and this susceptibility was related to some aspect of the muscle other than its fibre type composition. Surviving fibres in dorsiflexor and plantarflexor muscles did not reveal evidence of excitation-contraction uncoupling; they exhibited normal post-activation potentiation and fatigue properties. Some patients were initially incapable of exciting their motor units maximally during voluntary contractions. A finding of possible pathogenetic significance was that one patient, with prominent calves, developed exceptionally large voluntary torque in his plantarflexor muscles.Relatively little is known concerning the contractile properties of muscles in patients with limb girdle muscular dystrophy and the information available has come from two intrinsic muscles of the hand and foot, the adductor pollicis'-3 and the extensor digitorum brevis.4 Since the weakness in this disorder is most evident in larger, more proximal, muscles than in smaller distal ones, there is added interest in studying the former. Accordingly, in the present study measurements of voluntary and evoked contractions have been made in the dorsiflexor and plantarflexor muscles of the ankle, together with the associated muscle impulse activity. As in an earlier study of myotonic dystrophy,5 we have sought information concerning certain fundamental aspects of contractile behaviour in limb girdle muscular dystrophy; these are the relative involvement of fasttwitch and slow-twitch muscle fibres, the relationship between force development and evoked muscle impulse activity, the ability of patients to utilise fully their available muscle mass and the potentiating and fatigue properties of the dystrophic muscle fibres.

Gait Disturbances in Dystrophic Hamsters

“…Mutations in the sarcoglycan-gene result in limb-girdle muscular dystrophy (LGMD), of which there are different types [ 25 ]. The limb-girdle (shoulders and hips) muscles are usually the first affected, with muscle weakness becoming more progressive and spreading to more distal muscles, including tibialis anterior [ 26 ], wrists [ 27 ], and hands [ 28 ]. Delta-sarcoglycan deficiency results in LGMD-type 2F [ 29 ].…”