Identification of unexpected respiratory abnormalities in patients with amyotrophic lateral sclerosis through electromyographic analysis using intramuscular electrodes implanted for therapeutic diaphragmatic pacing.

BACKGROUND: Amyotrophic lateral sclerosis patients have significant respiratory abnormalities with incomplete understanding of respiratory control. This study analyzes electromyography (EMG) of the diaphragm (dEMG) using implanted diaphragm pacing (DP) electrodes.

METHODS: Retrospective analysis of dEMG data were obtained during Institutional Review Board and US Food and Drug Administration approved trials. The electrodes were used to analyze epochs of dEMG during multiple respiratory cycles.

RESULTS: Fifty-three patients were implanted. Thirty-six had bilateral dEMG assessments, 18 had continuous overnight readings with pulse oximetry, and 19 had serial analysis. Several findings revealed an alteration in the central respiratory drive including central apnea, hypoventilation, and hypercarbia. The electrodes showed unilateral dysfunction and demonstrated noninvasive ventilation suppression of diaphragm activity. DP can be used for serial monitoring, to decrease hypercarbia, improve sleep, and decrease atrophy.

CONCLUSIONS: Multiple abnormalities of respiratory control can be seen in amyotrophic lateral sclerosis patients using dEMG through therapeutic DP electrodes. DP is used to overcome instability of respiratory control when there are intact diaphragm motor units leading to improved survival.