Gait Abnormalities in a Patient with the Syndrome of Inappropriate Antidiuretic Hormone Secretion: A Case Studied with Gait Analysis

Hyponatremia, defined as serum sodium concentration <136 mEq/l, represents one of the most challenging clinical disorder in geriatric rehabilitative settings . It is associated with significant morbidity and mortality. Hyponatremia can be often followed by neurological symptoms caused by cerebral oedema and in severe hyponatremia, patients frequently experience balance disorder and a high risk of falls.

We report the case of a female patient, followed after an accurate diagnostic work-up for a syndrome of inappropriate antidiuresis (SIADH). Hyponatremia was initially treated with hypertonic saline infusion and then with fluid restriction. In consideration of the poor response to fluid restriction, treatment with tolvaptan was started. The patient experienced walking problems and was evaluated with an EMG computed Gait Analysis before and after that sodium level was normalized.

Gait analysis carried out highlighted neuromuscular instability with alteration of the time parameter and spatial postural deficit. Once corrected the hyposodiemia the patient showed a marked improvement in neuromuscular control with normalization of the temporal and spatial parameter of the step.

The clinical manifestations of the patient with SIADH are related to the severity of hyponatremia and the speed with which the sodium deficit is established. The criteria for the diagnosis of SIADH in a patient with hypotonic hyponatremia remain those established by Bartter and Schwartz in 1967. Our suggestions is so to monitor balance and gait disorders and perform serial measurements of urine and serum osmolarity during rehabilitation process in order to prevent unbalance and falling.