A case of central diabetes insipidus due to Rathke’s cyst presenting with nocturnal enuresis

Abstract

An 8-year-old boy with persistent nocturnal enuresis was admitted to the authors’ hospital. We suspected diabetes insipidus because his urine was hypotonic, and he had both polydipsia and polyuria. Magnetic resonance imaging (MRI) of the head revealed an 8-mm Rathke’s cyst within a sella turcica, and a water restriction test confirmed the diagnosis of partial central diabetes insipidus. When oral desmopressin was initiated, the nocturnal enuresis, polydipsia, and polyuria all resolved. Two years later, head MRI showed that the Rathke’s cyst had disappeared; however, oral medication was still required. After 2.5 years, his urine volume did not increase, even when he forgot to take his medicine; therefore, the medication was gradually reduced and stopped after 3 years. An improvement of symptoms after surgery has been reported in some cases of acute onset diabetes insipidus due to Rathke’s cyst. However, in cases with a chronic onset caused by an inflammatory spread from the cyst, an improvement after surgery has only rarely been reported. In this case, the diabetes insipidus improved and the patient’s height increased due to the spontaneous regression of the Rathke’s cyst, thus suggesting that the pressure caused by the cyst had most likely been the main cause of his symptoms.