A case of a cerebral cavernous malformation of the third ventricle that caused the syndrome of inappropriate secretion of antidiuretic hormone

BACKGROUND: Cerebral cavernous malformations (CCMs, also known as cavernous hemanigiomas) of the third ventricle are uncommon. Here, we present a rare case of a CCM that caused the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). CASE DESCRIPTION: A 68-year-old man presented with acute-onset cognitive and memory disturbance. Endocrinological examinations revealed hyponatremia due to SIADH. Computed tomography indicated a high-density mass in the third ventricle that caused left unilateral hydrocephalus due to obstruction of the foramen Monroe. On magnetic resonance imaging, the mass showed high intensity in both T1 and T2-weighted images and low intensity in susceptibility-weighted images, suggesting subacute intralesional hemorrhage. We completely excised the mass via a basal interhemispheric translamina terminalis approach. Intraoperatively, the mass adhered tightly to the left hypothalamus, which was supposed to the origin and was well circumscribed from the surroundings. The histopathological diagnosis was CCM, and his SIADH improved after the operation. CONCLUSION: We presented a rare case of a CCM in the third ventricle that caused SIADH, which improved after complete excision of the mass via a basal interhemispheric translamina terminalis approach.