MACRO EMG FOLLOW-UP-STUDY IN POSTPOLIOMYELITIS PATIENTS

We investigated the muscle strength and motor unit (MU) territory of f ive patients with postpolio syndrome (PPS), six stable patients with p rior poliomyelitis, and five healthy volunteers. The MU territory was assessed by measuring amplitudes of motor unit potentials (MUPs) recor ded by the macro EMG technique. The investigations were repeated after 11-20 months (mean 15.6). The macro MUP amplitudes in both patient gr oups were markedly increased (P = 0.02). However, no statistical diffe rence was found between the two groups in the initial amplitude values . Macro MUP amplitudes obtained on repeated examinations did not diffe r significantly from the initial macro MUP amplitudes in any of the th ree groups. In three individual PPS patients, a decline in muscle stre ngth on the follow-up study was documented, providing the diagnosis of post-poliomyelitis muscular atrophy (PPMA). The three PPMA patients h ad the highest initial macro MUPs. Two of them showed a decrease in ma cro MUP amplitudes on followup. These findings suggest that a later br eakdown of oversized MUs may play a role in the pathogenesis of PPMA.