The effect of excessive weight reduction on peripheral and central nervous functions. A study in obese patients treated by gastric banding.

Twenty-four obese patients were studied before and 3, 6, and 12 months after gastric banding to see if the excessive weight reduction caused any dysfunction of the peripheral or central nervous system or both. Postoperatively the patients were assumed to be able to keep their intake to 800-1000 kcal/day together with a multivitamin supplement. Electromyography, electroneurography and vibratory thresholds were used to assess the peripheral, somatosensory and visual evoked potentials to assess the central nervous and synaptic functions. Regular clinical and neurological assessments were made as well as laboratory examinations including total potassium estimations to calculate lean body mass. The mean weight loss and the mean lean body mass reduction amounted to 20.5% and 18.4% at 3 months, and to 30.3% and 10.2% at 12 months, respectively. Electromyography showed signs of acute denervation in the anterior tibial muscle in one patient 3 and 6 months after operation, but restitution after 12 months despite continuous weight loss. In the left peroneal nerve the electroneurography showed a trend with slight successive reduction of the conduction velocity in the postoperative period. No abnormalities of the vibratory thresholds were found postoperatively. Somatosensory and visual evoked potentials were normal in all patients and no significant changes were observed during the postoperative period. The present study did not reveal any significant dysfunction of the peripheral or central nervous system as a result of excessive weight loss in obese adults undergoing weight reducing surgery.