Electromyographic findings in primary lateral sclerosis during disease progression.

OBJECTIVE

To characterize electromyographic (EMG) findings in patients with primary lateral sclerosis (PLS) during the disease course.

METHODS

In PLS patients we scored spontaneous activity and motor unit action potential (MUP) pattern on EMG. We compared patients according to lower (group A) and higher (group B) EMG scores. EMG studies were repeated at intervals longer than 11 months; two or three repeat studies were required for inclusion in the analysis.

RESULTS

We studied 22 patients. Fasciculation potentials were found in 13 and fibrillations/positive sharp waves (fibs/sw) in 3 patients. Both were stable over time. Most patients had MUP abnormalities (n = 17), with worsening in the lower limbs in patients with three evaluations (p = 0.010). Compared to group A (n = 12), patients of group B (n = 10) had a significant shorter disease duration (median 10.9 vs 15.2 years, p < 0.001), lower functional score at both first (39 vs 45, p = 0.034) and last (29 vs 38, p = 0.003) evaluations, and had a faster functional decline (0.19 vs 0.08, p = 0.004).

CONCLUSIONS

Most PLS patients showed minor and stable EMG abnormalities, without progression to ALS. Patients with more EMG abnormalities have a faster progression.

SIGNIFICANCE: EMG abnormalities in most PLS patients are minor and stable.