Psychotic symptoms in normal pressure hydrocephalus

Normal Pressure Hydrocephalus due to idiopathic aqueductal stenosis is a chronic abnormal accumulation of cerebrospinal fluid in the cerebral ventricles caused by an obstruction in the Sylvian aqueduct. This leads to a dilatation of the ventricular system and to subsequent damage of the adjacent parenchyma. Although NPH typically presents with the progressive 'triad' of cognitive impairment, gait disturbance and urinary incontinence, it has been described that it rarely manifests in the form of predominant psychotic symptoms. It has been suggested that thought and perceptual disorders could develop secondary to the damage caused by NPH. Although precise anatomical correlates have not yet been established, certain cerebral regions -primarily the frontal cortex, mesencephalic and diencephalic structures of the brain- have been implicated in the pathogenesis of hydrocephalic psychosis. Because frontal lobe lesions are traditionally known to facilitate one's inability to integrate and correct perceptual distortions in the face of contradictory evidence, frontal lobe dysfunction may be integral in delineating the etiology of delusions in NPH. We present the case of a 30-year-old female, admitted involuntarily to our acute psychiatric department because she exhibited aggressive behavior while being in an agitated state with delusions of persecution. Her neurological examination disclosed subtle bradykinesia. Neuropsychological batteries and intelligence testing revealed mild cognitive impairment and a CT scan showed considerable dilatation of the ventricular system due to idiopathic aqueductal stenosis. While a conservative approach was chosen for the treatment of NPH, our patient was initiated on 2nd generation antipsychotics showing marked improvement of her psychiatric symptomatology. The atypical presentation of hydrocephalus in the aforementioned case underlines the necessity to thoroughly investigate the possible presence of an underlying organic factor in those patients who present with predominant psychotic symptoms in association with soft non-localising neurological signs and mild cognitive deficits. Furthermore, our patient's marked improvement indicates that, in cases where the primary cause is treated conservatively, hydrocephalic psychosis could respond to 2nd generation antipsychotics. In light of this case report, we reviewed past and present literature on the matter.