Ultrasound evaluation of the optic nerve in patients with severe symptomatic hyponatremia

Severe hyponatremia can precipitate significant neurological symptoms due to osmotic imbalances that induce intracranial hypertension (ICH). This study investigates the correlation between serum sodium levels and optic nerve sheath diameter (ONSD), measured by ultrasound, in patients presenting with symptomatic severe hyponatremia in the Emergency Department. Sixty-four patients with severe hyponatremia (Na⁺ < 125 mmol/L) and neurological symptoms were enrolled and compared to a matched control group. Serial measurements of serum sodium and ONSD were obtained at 3, 12, and 24 h post-correction. Results demonstrated a significant inverse correlation between sodium levels and ONSD, with ONSD decreasing as sodium levels were corrected (r = -0.71). ROC analysis confirmed ONSD as a sensitive and specific indicator of elevated intracranial pressure in these patients. This study highlights ultrasound ONSD measurement as a valuable non-invasive tool for monitoring ICH in severe hyponatremia, supporting its role in emergency settings to enhance diagnostic accuracy and therapeutic monitoring. Further research is needed to validate these findings and elucidate prognostic implications.