What happened, in summary

A 55-year-old woman had been diagnosed 2 years earlier with bilateral triple-negative breast cancer. She underwent bilateral mastectomy with sentinel-node biopsy and received doxorubicin, cyclophosphamide, paclitaxel and carboplatin. Two months into carboplatin, she developed severe headaches and reduced visual acuity, followed by clear fluid draining from the left side of her nose. The symptoms settled after chemotherapy ended. Two years later, the one-sided nasal drainage returned and was worse when she leaned forward. Evaluation supported a cerebrospinal-fluid leak caused by persistently raised intracranial pressure after chemotherapy-associated cerebral venous sinus thrombosis. During endoscopic surgery, clinicians identified a 5 mm skull-base defect in a pneumatised left pterygoid plate. The defect was repaired using a three-layer technique with a synthetic patch, septal cartilage and a middle-turbinate flap. She was kept upright after surgery, given a week of preventive antibiotics and started on acetazolamide to lower intracranial pressure and reduce the risk of another leak. There were no operative complications. Three months later, a brief episode of nasal drainage followed a long-haul flight and resolved after a temporary acetazolamide dose increase. At 12 months after the repair, the cerebrospinal-fluid leak had not recurred.