Correlation between a patient-derived functional questionnaire and abnormal neuromuscular transmission in Myasthenia Gravis patients

Objective To correlate the patient-derived physical function score, as measured by the disease specific Myasthenia Gravis Questionnaire (MGQ), and the score obtained with commonly used generic 36-item questionnaire, the Short-Form health survey (SF-36), with the degree of abnormal neuromuscular transmission measured by Single-Fibre EMG (SFEMG) and repetitive nerve stimulation (RNS) in Myasthenia Gravis (MG) patients. Methods SFEMG and RNS were performed in the deltoid muscle and SFEMG was also performed in the orbicularis oculi muscle in 45 MG patients. The patients were asked to fill out the MGQ, which has been translated and validated into Swedish, and the SF-36. The sum of MGQ items generates a global MGQ score. Items are also divided into 3 muscle specific domains: generalized, bulbar and ocular. Results The global MGQ score and generalized domain score of MGQ were strongly correlated with the degree of abnormal neuromuscular transmission, as measured by SFEMG in the deltoid muscle. Scores from ocular and bulbar domains of MGQ were not related to neurophysiological findings. Physical composite scores of SF-36 correlated significantly with the abnormal SFEMG findings in the deltoid. Conclusions The degree of disturbed neuromuscular transmission in a proximal limb muscle correlates with a patientʹs subjective experience of generalized myasthenic dysfunction. Significance The observed correlation adds a new dimension to neurophysiological examinations in patients with MG.