Clinical features of late-onset idiopathic aqueductal stenosis

Although late-onset idiopathic aqueductal stenosis (LIAS) is considered a good indication for endoscopic third ventriculostomy (ETV), the characteristics of this clinical entity have seldom been reported in the magnetic resonance (MR) imaging era. The authors reviewed their patients with LIAS who were treated by ETV to confirm its clinical features and response to treatment.

The study group was composed of 31 patients diagnosed with LIAS who were previously untreated. Both anatomic and cine phase-contrast MR studies were used to detect the obstruction of the aqueduct canal. The preoperative symptoms were statistically analyzed in relation to the age of the patients and the degree of preoperative ventriculomegaly.

The overall success rate of ETV was 83.9% with mean follow-up duration of 26.2 months. Only two patients had acute onset (within one month) without any predisposing chronic symptoms. The patients with chronic symptoms (longer than 6 months [n = 25]) can be divided into two major groups: a headache group (n = 12) and a normal pressure hydrocephalus (NPH)-symptom group (n = 11), Two patients had both headaches and NPH symptoms. The patients in the headache group were significantly younger and had smaller ventricles than the patients in the NPH group. With multivariate regression analysis, age independently affected the type of chronic symptoms.

LIAS typically presents with chronic onset, with younger patients tending to have headaches, and older patients tending to have NPH symptoms. ETV is considered the best surgical option, with more than an 80% success rate.