Abstract
Common fibular nerve (CFN) palsy is the most common mononeuropathy in the lower limb, and several etiologies are described. The CFN is the minor and lateral division of the sciatic nerve; it originates in the lumbar sacral division, and many risks of compression have been described: the behavior of crossing and squatting legs, extra and intraneural compressions, local trauma, and weight loss have been increasingly reported as important and noteworthy causes. The treatment is based on the severity of the nerve condition. In cases in which neurological impairment persists, surgical decompression is indicated. In cases of atraumatic palsy, compression of the fibular neck is the most important cause. The present is the report of a case of a 39-years-old male amateur cyclist who had undergone bariatric surgery and lost more than 30% of his initial body mass. Eleven months after the surgery, he performed a strenuous cycling session and evolved with paresthesia in dorsal left foot and dorsiflexion impairment. The electromyographic examination showed CFN palsy. The patient was submitted to surgical nerve decompression, with good results in ten months of follow-up. Strenuous physical activity after bariatric surgery with substantial weight loss can evolve with CFN palsy. This etiology should be considered in the clinical reasoning in such clinical presentation.