Foot Drop Following Peroneal Nerve Palsy: A Case Study of GLP-1 Inhibitor-Induced Weight Loss Complications

Case Diagnosis: A patient developed foot drop due to peroneal nerve palsy following significant weight loss associated with the use of a GLP-1 inhibitor.

Case Description or Program Description: A 59-year-old female with a medical history of CLL in 2022 and obesity presented with a gradually developing foot drop over several days, following six months of GLP-1 inhibitor use. There were no other neurological symptoms other than dorsiflexion and eversion weakness.

Setting: Outpatient EMG clinic.

Assessment/Results: EMG studies performed on her left leg revealed peroneal nerve conduction block affecting the deep more than the superficial fibers, consistent with peroneal nerve entrapment at the fibular head.

Discussion (relevance): GLP-1 inhibitors are known to induce rapid weight loss, which has been associated with peroneal nerve entrapment at the fibular head. Although the mechanism remains unclear, this case highlights a pattern where the deep peroneal nerve is more frequently affected than the superficial nerve, which has been commonly observed in patients with peroneal nerve compression at the fibular head. The reason the deep peroneal nerve is more affected than the superficial fibers is unclear but may relate to its anatomical positioning, traction injuries from deep fiber tethering in the fibular tunnel, or possible inflammatory infiltration of the nerve.

Conclusions: This case emphasizes the potential for GLP-1 inhibitors to contribute to peroneal nerve palsy through weight loss-induced nerve entrapment to the fibular head. Clinicians should be aware of this possible complication in patients undergoing significant weight loss with GLP-1 therapy and consider monitoring for neurological symptoms, especially in the lower extremities.