Reversible Focal Neurological Deficits Secondary to Severe Hyponatremia

Abstract

INTRODUCTION:Severe hyponatremia presents with nausea and vomiting, which progresses to lethargy, seizures, coma, and respiratory arrest as hyponatremia advances. Focal neurological deficits (FND) are uncommonly reported. Here we present a case of reversible FND in a patient with severe hyponatremia. CASE PRESENTATION:An 84-year-old female with hypertension and anxiety presents with stroke-like symptoms. She had several months of frequent falls and 2 weeks of word-finding difficulties, with progressive confusion, lethargy, slurred speech, and facial droop in the past week. Of note, she takes hydrochlorothiazide and was started on citalopram one week prior to presentation. On admission, blood pressure was 155/82 mmHg. Exam revealed aphasia, confusion, right-sided facial droop, and right-sided extremity weakness. Labs included sodium of 117 mEq/L, glucose of 160 mg/dL, urine osmolality of 450 mOsm/kg, and urine sodium of 105 mEq/L. Computed Tomography (CT) Brain was negative and CT angiography Head and Neck incidentally found a 1.5 cm spiculated nodule in the left upper lobe. Patient was admitted to the Intensive Care Unit (ICU) and received hypertonic saline. Hyponatremia was deemed secondary to Syndrome of Inappropriate Anti-Diuretic Hormone (SIADH) secretion from thiazide and citalopram use, and likely malignancy. Fluids were restricted and she was given salt tablets. Sodium levels improved and her neurological deficits completely resolved.DISCUSSION: Symptoms of hyponatremia traditionally include nausea, vomiting, gait instability, and coma. FND secondary to hyponatremia occur in only 5% of severe hyponatremia cases. While the relationship between FND and hyponatremia is poorly understood, FND are typically associated with intracranial bleeding, which was not seen in our patient. FND are often seen in cases of head trauma, tumors, stroke, meningitis, or encephalitis. In cases of hyponatremia where these conditions are not seen, hyponatremia-induced FND should be strongly considered. CONCLUSIONS:Severe hyponatremia may present with focal neurological deficits that resolve as sodium levels improve.