Hypoglossal nerve conduction studies in patients with obstructive sleep apnea

Abstract

EnAbstract Aim of the work To identify the correlation between obstructive sleep apnea (OSA) and motor nerve conduction study of hypoglossal nerve in terms of amplitude and terminal latency. Patients and methods The present study included 16 adult OSA patients who presented to the Otolaryngology outpatient clinic of the Suez Canal University Hospital. Exclusion criteria included previous significant facial trauma, head or neck cancer, previous surgery (including tonsillectomy or adenoidectomy), previous radiation therapy to head or neck, known diagnosis of peripheral neuropathy, any implanted device (nerve stimulator, implanted pump, pacemaker, and defibrillator), and known pregnancy. All patients were subjected to an assessment protocol that included thorough assessment of history (age, sex, snoring, nasal obstruction, and excessive daytime sleepiness), clinical examinations [BMI, apnea/hypopnea index (AHI), Friedman tongue position (FTP), and Mallampati grading], and electrophysiological studies of hypoglossal nerve. Results 87.5% of the patients had moderate to severe AHI (15 to >30). The degree of excessive daytime sleepiness was slight in 18.8% of the patients, mild in 50% of the patients, and moderate in 31.3% of the patients. FTP grades ranged from grade II (FTP II) (37.5%) to grade III (FTP III) (62.5%). Mallampati grading of tonsils also ranged from grade 2 (T2) (43.8%) to grade 3 (T3) (56.2%). Seventy-five percent of the patients had delayed distal latency of hypoglossal nerve. The mean distal latency of the patients was 3.24±123 ms, with the range of 2.5–7.7 ms. All the patients had low motor amplitude of the hypoglossal nerve. There were significant positive correlations between excessive daytime sleepiness and BMI, snoring, FTP, Mallampati grading, and decreased hypoglossal nerve distal latency. Conclusion Most patients with OSA had significantly impaired hypoglossal nerve conduction in the form of delayed distal latency and low motor amplitude.