ESPE Abstracts

Background: Periventricular nodular heterotopia (PNH) is a brain malformation caused by dysregulation of neuronal migration during cerebral development, resulting in nodular neuronal structures in the ventricular surface. Associated ectopy of the posterior pituitary has been reported in literature and is usually associated with deficiencies of the anterior pituitary. The occasion of an isolated central diabetes insipidus due to absence of the posterior pituitary has not been described in detail so far.

Case report: We report a 9-year-old girl with regular physical and cognitive development. The parents reported progressive polydipsia and polyuria, noticed from the age of 6 years during a varicella infection. While reporting a water intake of 5-6L per day, the patient did not reveal growth abnormalities nor biochemical evidence for malfunction of the anterior pituitary lobe. Water deprivation testing confirmed the diagnosis of diabetes insipidus with failure to increase urine osmolality and low copeptin levels despite hypernatremia. Cerebral MRI showed symmetrical periventricular heterotopias and a missing bright spot of the neurohypophysis.

Treatment with oral desmopressin 30μg reduced water intake to 2-3 liters per day. Whole exome sequencing in the patient did not reveal causative variants in known genes for PNH, diabetes insipidus or immunodeficiency and chromosomal microarray analysis was normal.

Discussion: Although PNH is associated with other structural brain abnormalities, isolated absence of the posterior pituitary is extremely rare. Single cases of EPP with PNH in non-SOD patients have been described, all featuring growth hormone deficiency as symptom of anterior pituitary lobe affection. Bilateral posterior PNH (BP-PNH) as described by Mandelstam et al. 2013, represents a distinct subtype of PNH, featuring noncontiguous and asymmetric lesions. Similar to the findings in our patient, no genetic cause of BP-PNH could be identified so far. While 10% of patients with BP-PNH were shown to feature posterior pituitary abnormalities, only one patient has been described with absent bright spot so far.

Conclusion: The case of a patient with isolated central diabetes insipidus underlines the importance of evaluation of pituitary function in association to PNH. A common genetic origin in the distinct sub-entity of BP-PNH remains to be determined.