Psychosis, Intermittent Hyponatraemia, Polydipsia and Neuroleptic Malignant Syndrome in a Patient with Schizophrenia

The syndromes of psychosis, intermittent hyponatraemia and polydipsia (PIP) and neuroleptic malignant syndrome (NMS) are rare. Rarer still is their concomitant occurrence. This case report describes a 44 year old, schizophrenic, Caucasian female who presented with vomiting and confusion. A subsequent seizure and fluctuating consciousness prompted rapid investigation revealing a very low sodium level. These symptoms coupled with a history of excessive water consumption in the weeks preceding admission led to the diagnosis of PIP syndrome. Intensive care led to an initial recovery, however the patient deteriorated again, developing fever and muscle rigidity. A subsequent elevated creatine kinase level led to the diagnosis of NMS and antipsychotic medication was stopped. Upon stabilisation she was transferred to psychiatric care and managed with closely monitored antipsychotic medication. The exact pathogenesis of these two syndromes is not well understood. Neither is their potential to have a synergistic effect. Though polydipsia and hyponatraemia are well documented in psychiatric patients, whether or not there is an underlying disorder leading to excessive water consumption is unclear, as is the association between NMS and hyponatraemia. PIP is thought to be related to a dysfunction in the limbic system. In addition to this several investigators have shown that NMS is related to the degree of D2 receptor blockade. Both typical and atypical antipsychotics can lead to NMS. The co-existence of these two conditions can have important implications for their diagnosis and management.