Axonal polyneuropathy in obstructive sleep apnoea.

Chronic hypoxaemia in chronic obstructive pulmonary disease is a well known risk factor for polyneuropathy but the impact of intermittent hypoxaemia on peripheral nerve function has not been established so far. A case-control study was performed to evaluate the prevalence of polyneuropathy in obstructive sleep apnoea (OSA). Out of 24 patients with OSA, 17 (71%) had clinical signs of polyneuropathy versus seven (33%) out of 21 matched controls. The mean amplitude of the sural sensory nerve action potential was smaller in the OSA group than in the control group, indicating axonal nerve damage. The differences were significant and could not be attributed to other known risk factors for polyneuropathy. The severity of axonal damage in patients with OSA correlated with the percentage of the night time with an O(2) saturation below 90%. It is assumed that recurrent intermittent hypoxaemia in OSA is an independent risk factor for axonal damage of peripheral nerves.