Cerebral Salt-Wasting Syndrome - Causes, Diagnosis and Treatment

Introduction:

Cerebral salt-wasting syndrome is an uncommon endocrine condition that presents symptoms like hyponatremia (decreased blood sodium concentration) and dehydration. The cerebral salt-wasting syndrome typically manifests within the first week following a brain injury or infection and subsides on its own within two to four weeks; however, it can sometimes persist for months or years. The exact cause of the syndrome is unknown and why this syndrome occurs after certain diseases and does not occur after other conditions is unclear. In addition, the symptoms of the cerebral salt wasting syndrome are very similar to that of the syndrome of inappropriate antidiuretic hormone secretion. Therefore, it is essential to correctly diagnose these two conditions because the treatment modalities are very different for these syndromes.

What Is Cerebral Salt-Wasting Syndrome?

When the brain is injured (due to trauma) or has tumors in or around it, an uncommon endocrine disorder known as cerebral salt-wasting syndrome develops that causes low blood sodium concentration and dehydration. In this condition, the patient has a normal adrenal gland and normal thyroid gland functioning. Moreover, kidney functioning is also standard, except for excess sodium excretion. The exact cause of the condition is unknown, and there is no definitive treatment for cerebral salt-wasting syndrome. The cerebral salt-wasting syndrome is often categorized as a syndrome of inappropriate antidiuretic hormone secretion. Because both conditions can manifest with hyponatremia and concentrated urine with sodium excretion in the urine, it can be challenging to distinguish this condition from the syndrome of inappropriate antidiuretic hormone secretion (SIADH). However, it is essential to differentiate between both conditions because their treatment approaches are different.

What Causes Cerebral Salt-Wasting Syndrome?

The exact cause of cerebral salt-wasting syndrome is not exactly understood. Moreover, some of the common causes of cerebral salt-wasting syndrome are:

• Aneurysmal subarachnoid hemorrhage (bleeding between the brain and the tissue surrounding the brain).

• Surgery of pituitary tumors.

• Surgery for acoustic neuroma (a benign tumor that grows on the nerves connecting the inner ear to the brain).

• Surgery for calvarial remodeling.

• Surgery for glioma (a cancerous tumor of the nervous system's glial tissues).

• Tuberculous meningitis.

• Viral meningitis.

• Metastatic carcinoma.

• Injury to the skull.

Is Cerebral Salt-Wasting Syndrome a Common Condition?

Cerebral salt-wasting syndrome is a rare condition, but the exact rate of incidence and prevalence of the condition is not known. However, according to some studies, cerebral salt wasting causes up to 25 percent of severe hyponatremia following aneurysmal subarachnoid hemorrhage.

What Are the Symptoms of Cerebral Salt-Wasting Syndrome?

Common signs and symptoms of the cerebral salt-wasting syndrome are:

• Symptoms of cerebral salt-wasting syndrome are usually associated with severe hyponatremia or dehydration.

• Severe and acute central nervous system (CNS) dysfunctioning associated with the cerebral salt-wasting syndrome will cause changes in mental status, prolonged periods of unconsciousness (coma), and seizures (fits).

• Frequent urination.

• A large volume of urine excretion.

• An increased amount of sodium in the urine.

• Decreased blood sodium level.

• Increased thirst.

• Salt cravings.

• Muscle cramps.

• Dizziness and vertigo.

• Feeling lightheaded.

• Anxiety.

• Increased or decreased heart rate.

• Low blood pressure (hypotension).

• Headaches and fainting.

• Constipation.

• Nausea and vomiting.

• Acid reflux.

• Chest pain.

• Nerve pain.

How Is Cerebral Salt-Wasting Syndrome Diagnosed?

In individuals with cerebral salt-wasting syndrome, the following laboratory tests may be recommended:

• Serum Sodium Level: This test is done because patients with cerebral salt-wasting disease who are untreated frequently have hyponatremia.

• Serum Osmolality: If the measured blood osmolality is twice as high as the serum sodium level and the level of urea and other nitrogen compounds in the blood are not elevated, increased blood sugar level may be the cause of decreased sodium level.

• Urinary Output: Urine flow is generally elevated in the case of cerebral salt-wasting syndrome.

• SIADH: It is crucial to distinguish between cerebral salt-wasting syndrome and the syndrome of inappropriate antidiuretic hormone secretion because both treatments are highly different. In contrast to the hypovolemic appearance of cerebral salt wasting syndrome, the patient with SIADH is euvolemic to hypervolemic due to the retained free water.

What Is the Difference Between Cerebral Salt Wasting Syndrome and the Syndrome of Inappropriate Antidiuretic Hormone Secretion?

Both syndromes have characteristic hyponatremia (decreased blood sodium levels) with an elevated level of sodium in the urine, concentrated urine, and absence of any swelling. However, the primary differentiating criteria are that in cerebral salt wasting, the patient is hypovolemic (decreased amount of circulating blood in the body), whereas, in SIADH, the patients are euvolemic (have a normal volume of blood and fluids in the body) to hypervolemic (abnormally increased volume of blood).

How Is Cerebral Salt-Wasting Syndrome Treated?

• The first treatment plans focus on addressing the underlying subarachnoid hemorrhage, aneurysm, or other central nervous system diseases because cerebral salt wasting usually happens after these conditions.

• Next, while treating hyponatremia, the patient's reduced blood sodium volume must be restored. For mild to severe cases of hyponatremia of cerebral salt wasting syndrome, the patient is typically given isotonic saline. Hypovolemic patients are treated with isotonic fluid, which also aids in restoring the body's sodium reserves.

• More active sodium replacement may be needed for moderate to severe cases of hyponatremia. This will include restricting free water consumption and using hypertonic saline solutions like three percent hypertonic saline or salt tabs. The dosage of salt tablets is one to two grams, up to three times a day.

• Some healthcare professionals have advocated the idea of using Fludrocortisone to treat cerebral salt-wasting syndrome.

• Regular monitoring of the serum sodium level is necessary while treating hyponatremia. Hypernatremia can result from overcorrection of the serum sodium level.

Conclusion:

Cerebral salt wasting syndrome generally occurs after central nervous system diseases such as aneurysmal subarachnoid hemorrhage. Treatment for such patients must be done by multiple specialties because the treatment of cerebral salt wasting syndrome includes additional fluid volume, which can cause issues like swelling in the brain, swelling in the lungs, heart failure, and kidney dysfunction. Special care should be taken to avoid restoring excessive free water. Patients affected by cerebral salt-wasting syndrome can require prolonged treatment for their hyponatremia.