Cerebral salt-wasting syndrome


Cerebral salt-wasting syndrome is a rare endocrine condition featuring a low blood sodium concentration and dehydration in response to injury or the presence of tumors in or surrounding the brain. In this condition, the kidney is functioning normally but excreting excessive sodium. The condition was initially described in 1950. Its cause and management remain controversial.

Signs and symptoms

Signs and symptoms of CSWS include large amounts of urination, high amounts of sodium in the urine, low blood sodium concentration, excessive thirst, extreme salt cravings, dysfunction of the autonomic nervous system, and dehydration. Patients often self-medicate by consuming high amounts of sodium and by dramatically increasing their water intake. Advanced symptoms include muscle cramps, lightheadedness, dizziness or vertigo, feelings of anxiety or panic, increased heart rate or slowed heart rate, low blood pressure and orthostatic hypotension which can result in fainting. Other symptoms frequently associated with dysautonomia include headaches, pallor, malaise, facial flushing, constipation or diarrhea, nausea, acid reflux, visual disturbances, numbness, nerve pain, trouble breathing, chest pain, loss of consciousness, and seizures.

Causes

CSWS is usually caused by brain injury/trauma or cerebral lesion, tumor, or hematoma.

Diagnosis

CSWS is a diagnosis of exclusion and may be difficult to distinguish from the syndrome of inappropriate antidiuretic hormone, which develops under similar circumstances and also presents with hyponatremia. The main clinical difference is that of total fluid status of the patient: CSWS leads to a relative or overt low blood volume whereas SIADH is consistent with a normal or high blood volume. If blood-sodium levels increase when fluids are restricted, SIADH is more likely. Additionally, urine output is classically low in SIADH and elevated in CSWS.

Treatment

While CSWS usually appears within the first week after brain injury and spontaneously resolves in 2–4 weeks, it can sometimes last for months or years. In contrast to the use of fluid restriction to treat SIADH, CSWS is treated by replacing the urinary losses of water and sodium with hydration and sodium replacement. The mineralocorticoid medication fludrocortisone can also improve the low sodium level.