Peripheral neuropathy in chronic obstructive pulmonary disease

Abstract

IntroductionPeripheral neuropathy in chronic obstructive pulmonary disease (COPD) has received scanty attention. The purpose of this study was to evaluate objectively the functional changes in the peripheral nervous system in COPD by different electrophysiological parameters and to determine the frequencies of these changes in patients with COPD.AimAssessment of peripheral nerve conduction by evaluation of the motor and sensory nerve conduction (SNC) in COPD patients.Patients and methodsIn this case–control study, we recruited 25 COPD patients and matched 25 healthy controls. Motor and SNC studies for ulnar and median nerves were evaluated by means of electrophysiological nerve study. Motor nerve conduction velocity and sensory nerve conduction velocity (SNCV), distal latencies (DLs), and amplitude of compound motor action potential were recorded. Arterial blood gases including partial pressure of oxygen and carbon dioxide (PaO2and PaCO2), oxygen saturation (SaO2), and arterial pH were measured. Pulmonary function test was done and forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio were measured.ResultsThere was a significant difference between COPD patients and the control group in all spirometric and gasometric parameters recorded, except for the arterial pH. On studying motor nerve conduction through median and ulnar nerves, there was an increase in DL, decrease in motor nerve conduction velocity, and longer F-wave latency in the COPD group than in the control group in both nerves. SNC study of the median nerve revealed a decrease in SNCV and an increase in DL in the COPD group than in the control group. Median nerve motor neuropathy was proved in 28% of patients, ulnar nerve motor neuropathy was proved in 36% of patients, whereas sensory nerve study of median nerve proved that 68% of patients have sensory axonal neuropathy and 12% have demyelinating sensory neuropathy. Median nerve Distal Latency (DL) shows negative correlation with FEV1and FEV1/FVC ratio. SNCV of the median nerve was positively correlated to oxygen tension level.ConclusionThe incidence of neuropathy is high. The rate of axonal neuropathy was significantly higher than other types. Our study showed a significant positive correlation between the degree of hypoxemia and severity of neuropathy, whereas it showed negative correlation between spirometry parameters (FEV1and FEV1/FVC ratio) and median nerve DL.