When Cancer Mimics Epilepsy: Focal Seizures Caused by Hypermagnesemia, Hyperphosphatemia, and Hypercalcemia from Breast Malignancy

Neurological presentations of malignancies are quite rare, especially for tumors outside of the central nervous system. Usually, these presentations are secondary to metastasis to the brain or underlying metabolic derangement. This case presents a 62-year-old female who presented to the emergency department with drowsiness and later focal seizures. After laboratory and radiological investigations, she was diagnosed with stage four breast cancer with bone metastasis, causing electrolyte disturbances, leading to her presentation. This case highlights the importance of considering metabolic etiologies when evaluating focal seizures, especially in patients with malignancy. These abnormalities are more common in this population, particularly in patients with bone metastasis. Prompt identification and diagnosis of such reversible causes can alter the clinical management and improve patient outcomes.