Peroneal Nerve Palsy With Foot Drop: A Rare Manifestation of Oxaliplatin Toxicity

Oxaliplatin is a platinum-based chemotherapy drug that is distinguished from others in its class by its neurotoxicity. This toxicity most commonly presents as a peripheral neuropathy with sensory symptoms, and less frequently as motor or autonomic disorders. Peroneal nerve palsy is a mononeuropathy presenting with foot drop and may result from multiple causes. Its occurrence in association with chemotherapy, particularly oxaliplatin, is rare. We report two cases of peroneal nerve palsy associated with oxaliplatin treatment. Case 1 involves a 73-year-old female with stage IV pancreatic adenocarcinoma who developed a left foot drop after four cycles of modified FOLFIRINOX (oxaliplatin 85 mg/m²). Neurological examination revealed distal weakness (3/5) without additional deficits. Electromyography confirmed axonal and demyelinating injury of the left common peroneal nerve (CPN). Other causes were ruled out. Following oxaliplatin discontinuation, the deficit completely resolved. Case 2 involves a 62-year-old male diagnosed with adenocarcinoma of the gastroesophageal junction who underwent neoadjuvant chemoradiotherapy with carboplatin (AUC 2) plus paclitaxel (50 mg/m²) and presented with metastatic disease five months later. After four cycles of FOLFOX (oxaliplatin 85 mg/m²), he developed a painless right foot drop with isolated motor deficit (0/5). Laboratory tests, brain CT, and spine MRI excluded alternative causes. Disease progression precluded further evaluation, and the patient died before the clinical course of the palsy could be assessed. These two cases highlight the potential of oxaliplatin-induced neurotoxicity to manifest as an isolated peroneal nerve palsy with foot drop. Given that only six cases of this condition have been described in the literature so far, further case reports are essential to better characterize risk factors, clinical course, and outcomes of this rare complication.