Subclinical peripheral neuropathy associated with chronic obstructive pulmonary disease

Peripheral nervous system disorders in COPD (chronic obstructive pulmonary disease) have been found more frequently than usual neurologic practice. We planned this prospective clinical and electrophysiological study to determine the incidence and characteristics of neuropathy in patients with COPD. We studied 49 patients with COPD in whom other causes of polyneuropathy had been excluded. COPD patients were divided into two groups: 21 hypoxemic and 28 normoxemic. Age and sex matched, nonsmoker, 21 healthy subjects were included as the control group. We investigated the results of clinical (neurological symptom score-NSS, neurological disability score-NDS and vibration perception thresholds- VPT) and neurophysiological evaluations in COPD patients and the control group. A value over the mean +/- 2.5 SD of control group were accepted pathologic. NSS results were pathologic in 34% of COPD patients, NDS in 42% and VPT in 94%. Carpal tunnel syndrome was found in 24% of the patients, neuropathy in 55%, and polyneuropathy in 44.8%. In conclusion, the incidence of neuropathy was more than expected, the rate of axonal neuropathy was significantly higher in the hypoxemic group than normoxemic group and the severity of neuropathy was correlated with the degree of hypoxemia.