Distal myasthenia gravis frequency and clinical course in a large prospective series

In Myasthenia gravis (MG) proximal limb, ocular and/or bulbar muscles are most commonly affected, whereas distal extremity muscles are typically spared. The aim of the current study was to assess the frequency of primarily distal MG in the Tyrol and to describe its clinical peculiarities.

Over the past 20 years 84 patients with MG have undergone follow-up at the Department of Neurology of Innsbruck University. Types of presentation, clinical course and treatment response were followed over a period of 20 years (1980-2000).

Six of 84 MG patients showed a predominance of muscle weakness and fatigability in distal limb muscles (two at presentation, four over the later course of the illness). There was no difference between distal MG and MG with a more typical distribution of muscle weakness regarding age, gender and response to therapy.

The case series indicates that predominantly distal presentations of otherwise typical MG are more frequent than generally assumed and should be considered in the differential diagnosis of diseases with distal limb weakness.