Peripheral Neuropathy and Abnormal Visual Evoked Potentials in Stable Patients with Chronic Obstructive Pulmonary Disease

Objective: To know the frequency and predictors of peripheral neuropathy and the abnormal visual evoked potentials in stable patients with chronic obstructive pulmonary disease. Material & Methods: All consecutive patients of stable COPD of age ≥ 40 years were screened for peripheral neuropathy. Total 57 patients of stable COPD of age ≥ 40 Years were selected. Spirometric examination was done in all the patients using an electronic portable based spirometer with printer. Neurophysiological evaluation (neurological disability score-NDS), Mini Mental State Examination-questionnaire (MMSE), Visual analogue scale (VAS) were done on all subjects. The following nerves were evaluated for latency, amplitude, and conduction velocity. For motor nerve conduction: median, ulnar, common peroneal and tibial nerves were evaluated. For sensory nerve conduction: median, ulnar and sural nerves were evaluated. VEP was evaluated in all the 57 subjects. The continuous variables were described using means and analysis was done using independent t test. Results: Sub-clinical neuropathy was seen in 28 (49%) out of 57 stable COPD patients. Sensory neuropathy was seen in majority of patients. Sural nerve was the most commonly involved nerve. Neuropathy was predominantly axonal in nature. Abnormal VEP was found in 18 (32%) patients in whom P100 latency was more than 107. Conclusions: Electro-physiological testing showed the presence of peripheral neuropathy in 49% patients and abnormal VEP in 32% patients with stable COPD, who had no neurological symptoms. Maximum number of stable COPD patients with severe obstruction, heavy smoking index and bio-mass exposure had peripheral neuropathy, but statistically this was not found significant.