Recurrent Hyponatremia After Traumatic Brain Injury

Abstract

Dysregulation of the neuroendocrine system is a frequent complication after traumatic brain injury (TBI). Symptoms of these hormonal abnormalities might be subtle and thus easily ignored. Hyponatremia usually indicates underlying disorders that disrupt fluid homeostasis. In most patients with TBI, hyponatremia is a feature of the syndrome of inappropriate antidiuretic hormone (SIADH) secretion due to pituitary dysfunction after head injury. Usually TBI-associated hyponatremia is transient and reversible. We report the case of a 48-year-old man with TBI-associated hyponatremia with delayed recovery and recurrent hyponatremia precipitated by subsequent surgery. In this report, we emphasize the importance of identifying patients with slow recovery of the injured brain, which could complicate with SIADH and acute hyponatremia. Differentiating TBI-associated SIADH from other important causes of hyponatremia such as cerebral salt wasting, and hypocortisonism are also reviewed. Prevention of its recurrence by avoiding further risk is mandatory in managing patients with TBI. KEY H yponatremia is a common disorder encountered in various settings. 1 In most cases, hyponatremia manifests as an underlying disease and degree of hyponatremia usually indicates severity of etiology, and can even correlate with patient outcome. 2 Clinical features of hyponatremia are confined to most neurological manifestations, but vary with severity and rate of progression. Hyponatremia is one of the clues for diagnosing disease that might not be detected directly. Moreover, in certain circumstances, hyponatremia can even provide significant prognostic implications. 1 Traumatic brain injury (TBI) may severely impair brain function. In addition to structural damage, neuroendocrine dysfunction is an important complication. 3 The pituitary insult can manifest with any hormone dysregulation involving either the anterior or posterior pituitary gland. 4,5 Most TBI-associated hyponatremia is mild and asymptomatic, and lasts only a short time. The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) commonly underlies acute hyponatremia in these patients. 6 Because the neurological manifestations of hyponatremia and acute brain injury are quite similar, differentiation may be difficult. Furthermore, unresolved recurrent hyponatremia with obvious clinical manifestations has rarely been described. We report here a patient with recurrent symptomatic hyponatremia after head injury. Case ReportA 48-year-old man was sent to our emergency department because of an accidental fall, and head injury 4 days before admission. He had originally been admitted to a local hospital where brain computed tomography revealed no intracranial hemorrhage or skull fracture. However, he developed progressive headaches, deteriorated consciousness, and vomiting that were refractory to medical treatment. Repeated brain computed tomography at our institution disclosed minimal bilateral frontal subdural hematoma. Biochemical examination found a rapid drop ...

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