Neurophysiological investigations in patients with sleep apnoea syndrome

UNLABELLED: The untreated sleep apnoea syndrome (SAS) is associated with cardiovascular complications (arterial hypertension, coronary heart disease, cardiac arrhythmia) and increased morbidity and mortality. Disorders of the autonomic nervous system function are probably responsible for cardiac arrhythmia. Most researchers evaluated autonomic function using cardiovascular tests. The aim of our study was to assess whether neurophysiological method--sympathetic skin response (SSR)--could be useful in testing function of the autonomic nervous system in patients with SAS. MATERIAL AND METHODS: The examined group consisted of 26 patients with SAS recognised by polysomnography (mean apnoea index: 42 +/- 31, mean age: 52 +/- 9 years). The control group consisted of 27 healthy volunteers (mean age: 50.5 +/- 3 years). SSR was recorded simultaneously from the right palm and right foot. Latencies and amplitudes of SSR were measured. Recordings were carried out using an electromyograph (Counterpoint). Statistical analysis was performed using student's t-test. RESULTS: We could not obtain SSR in 10 patients with SAS (38.5%). In the remaining patients the SSR amplitudes in the upper limb were significantly lower (250.6 +/- 131 uV) than in the control group (582.8 +/- 76.7 uV) (p < 0.001). The SSR amplitudes in the lower limb were also decreased (128.1 +/- 77 uV), but not significantly, in comparison to control group (156.9 +/- 28.3 uV). We did not observe changes in latencies between the groups. CONCLUSIONS: Results of our study provide evidence for autonomic disorders in patients with SAS. Sympathetic skin response (SSR) is a simple and fast neurophysiological method useful in testing function of the autonomic nervous system in patients with SAS.