The syndrome of self-induced water intoxication in psychiatric patients

This is a report on six psychiatric patients who indulged in excessive ingestion of water and subsequently developed tonic-clonic seizures in the course of the underlying mental disorders. On the basis of the DSM-III criteria, they were diagnosed as follows: schizophrenic disorder, 4; schizo-affective disorder, 1; borderline personality disorder, 1. The levels of serum electrolytes were estimated during five episodes of seizures in three patients. Hyponatremia was a consistent finding (serum sodium: mean = 120.6 mEq/liter). Plasma osmolality and plasma levels of arginine vasopressin (AVP) were determined during two episodes in two patients. The inappropriately high circulating levels of AVP relative to plasma hypoosmolality were documented. However, the response to the overnight fluid deprivation and acute water load during the period of no seizures in two patients revealed no evidence of the persistent SIADH, suggesting the temporal association of hyponatremic encephalopathy with inappropriate AVP secretion. It is not conclusive whether the transient SIADH is the cause or the consequence of hyponatremic encephalopathy, although a delusion or an auditory hallucination could play a critical role in drinking water excessively in three patients.