Tubercular meningitis presenting as cerebral salt wasting syndrome in an adult: A case report

Introduction: Cerebral salt wasting syndrome (CSWS) is a cause of hyponatremia in the setting of intracranial pathologies such as Central Nervous System (CNS) trauma, infections, and tumors. It is important to differentiate CSWS from the syndrome of inappropriate antidiuretic hormone secretion (SIADH) as their management differs. CSWS leads to hypovolemia as opposed to euvolemia or hypervolemia in SIADH. SIADH is managed with fluid restriction and this could worsen CSWS which is managed with adminstration of intravenous crystalloids to correct hyponatremia. Case summary: A 42-year-old male was admitted after a week of low-grade fever with easy fatigability, hypersomnolence, and excessive thirst. He had polyuria which started 5 days before presentation, and unintentionally lost 3 kg of weight in the past month. He had orthostatic hypotension, and was dehydrated, but vital signs were normal with the exception of his temperature. Cerebrospinal fluid (CSF) analysis revealed a glucose of 42 mg/dl, protein 170 mg/dl, cell count 28/mm3 with 65% lymphocytes which was consistant with tubercular meningitis. CSF AFB culture was positive in addition to a positive CSF PCR for M. tuberculosis. Discussion: Presentation of CNS infection with tuberculosis may be non-specific and its insidious onset could lead to delayed or missed diagnosis; however persistent constitutional symptoms and signs with history of weight loss and a close contact with tuberculosis may raise the possibility of tuberculosis. Early diagnosis and treatment has an excellent prognosis, but any delay contributes to death and disability despite anti-tubercular drug therapy. CSWS should be managed with salt and volume replacement, but more importantly, the causative CNS insult should also be confirmed and addressed.