Diffuse infiltration of the meninges by metastatic carcinoma (meningeal carcinomastosis) is a potential complication of systemic malignancy. It may present with a variety of neurological symptoms as any aspect of the neuraxis can be affected. Often there is a history of pre-existing malignancy. The authors describe a case with an initial presentation of sudden onset profound bilateral sensorineural hearing loss. The underlying pathology was found to be an occult breast carcinoma, a previously unreported finding. The role of cerebrospinal fluid cytology and radio-imaging in diagnosis is discussed. All previously reported cases of sudden hearing loss and meningeal carcinomatosis are reviewed.