Correlations between MUNIX and adapted multiple point stimulation MUNE methods.

OBJECTIVE: The aim of this study was to evaluate how the motor unit number index (MUNIX) is related to the adapted multiple point stimulation (AMPS) technique.

METHODS: MUNIX and AMPS technique were prospectively performed on thenar muscles in 20 consecutive patients referred to our neurophysiological laboratory with the clinical diagnosis of a possible motoneurone disorder (MND). The clinical and paraclinical assessment confirmed the diagnosis of MND in 13 out of 20 patients, amyotrophic lateral sclerosis (ALS) in 9 (with MND group). In the other 7 patients, there were neither evidence of MND, nor of any peripheral nervous system disease (without MND group).

RESULTS: AMPS and MUNIX data were significantly (p < 0.001) lower in patients with MND than in patients without MND. There was a strong significant positive linear correlation between AMPS and MUNIX values (n = 20; R = 0.83; p < 0.01).

CONCLUSION: Both MUNIX and AMPS methods could serve as a reliable marker to document the motor unit loss.

SIGNIFICANCE: The present paper constitutes one more clue of MUNIX reliability.