What is the relationship between head trauma and hyponatremia (low sodium levels)?

From the Guidelines

Head trauma patients with hyponatremia should be managed with fludrocortisone to reduce excess sodium excretion, urine volume, and hyponatremia, as it has been shown to be effective in moderately sized RCTs without significant morbidity, except for hypokalemia, which requires potassium supplementation 1. In the context of head trauma and hyponatremia, it is crucial to address the hyponatremia to prevent further neurological deterioration. The management of hyponatremia in head trauma patients involves identifying the underlying cause, which could be syndrome of inappropriate antidiuretic hormone secretion (SIADH), cerebral salt wasting, or medication effects. Key considerations in management include:

• Correcting sodium levels gradually to avoid osmotic demyelination syndrome
• Using 3% hypertonic saline for severe symptoms
• Implementing fluid restriction for asymptomatic or mildly symptomatic patients
• Regular monitoring of serum sodium levels The use of fludrocortisone, as recommended by the 2023 guideline for the management of patients with aneurysmal subarachnoid hemorrhage 1, is a critical component of this management strategy, given its efficacy in reducing hyponatremia and its relatively favorable side effect profile compared to other agents like high-dose hydrocortisone. It is also important to consider the potential complications of hyponatremia in head trauma, including worsening cerebral edema and increased intracranial pressure, and the risks associated with overly rapid correction of sodium levels, such as permanent neurological damage. Therefore, a careful and multidisciplinary approach, including neurosurgical consultation, is necessary for the optimal management of head trauma patients with hyponatremia.

From the FDA Drug Label

Symptomatic patients, patients likely to require saline therapy during the course of therapy, patients with acute and transient hyponatremia associated with head trauma or postoperative state and patients with hyponatremia due to primary polydipsia, uncontrolled adrenal insufficiency or uncontrolled hypothyroidism were excluded

Patients with head trauma and associated hyponatremia were excluded from the studies.

• The FDA drug label does not provide information on the use of tolvaptan in patients with head trauma and hyponatremia 2. The FDA drug label does not answer the question.

From the Research

Head Trauma and Hyponatremia

• Hyponatremia is a common electrolyte abnormality in traumatic brain injury (TBI) and is an independent predictor of poor neurologic outcome 3.
• The incidence of hyponatremia in TBI patients varies widely, with one study reporting an incidence of 13.2% 3 and another study reporting an incidence of 29% 4.
• Hyponatremia can be caused by various factors, including the syndrome of inappropriate antidiuretic hormone secretion (SIADH) and cerebral salt wasting (CSW) 3, 5.
• The management of hyponatremia in TBI patients is crucial, as it can affect the outcome and hospital stay 3, 4.
• Early therapy with fludrocortisone can significantly reduce the duration of hospital stay in TBI patients with hyponatremia 3.
• The use of saline hydration and fludrocortisone can be effective in managing cerebral salt wasting in patients with head trauma 6.
• Factors associated with hyponatremia in TBI patients include greater age, worse injury severity score, worse Marshall Grade on CT, and a diffuse pattern of injury on CT 4.

Diagnosis and Management

• Hyponatremia is defined as a serum sodium level of less than 135 mEq/L and can be categorized into hypovolemic, euvolemic, or hypervolemic hyponatremia 7.
• The approach to managing hyponatremia should consist of treating the underlying cause, and urea and vaptans can be effective treatments for SIADH and hyponatremia in patients with heart failure 7.
• Severely symptomatic hyponatremia is a medical emergency and should be treated with bolus hypertonic saline to reverse hyponatremic encephalopathy 7.
• Overly rapid correction of chronic hyponatremia can cause osmotic demyelination, a rare but severe neurological condition 7.

Risk Factors

• Older patients and those with more significant injury on CT are more at risk of developing hyponatremia after TBI 4.
• A diffuse pattern of injury on CT, the presence of intracerebral hemorrhage, and multiple lesions on CT are also associated with significant hyponatremia in TBI patients 4.