Long-term outcomes of endoscopic third ventriculostomy for Blake's pouch cyst in adults

The optimal treatment method for persistent Blake's pouch cyst (BPC) remains unclear owing to its low prevalence. We aimed to characterize a patient population with adult BPC and to identify the risk factors associated with endoscopic third ventriculostomy (ETV) for BPC. This study reports the largest number of BPC cases in adults and is the first report to reveal the long-term outcomes of ETV in such patients.

We performed a retrospective analysis of data collected from seven adult patients with BPC between 2005 and 2019. They underwent ETV at the Kurume University Hospital and were followed up for five years or more. We extracted data regarding patient age, sex, clinical symptoms, radiological imaging, intraoperative findings and outcomes.

The ages of the patients ranged between 30 and 60 years (45 ± 12 years). The mean postoperative follow-up time was 92.1 ± 13.5 months. The overall success rate was 71.4%. The most frequent symptom was headache (86%), followed by mild cognitive impairment (71%). The average cerebrospinal fluid pressure was slightly elevated (18.4 ± 1.4 cmH2O). A decrease in ventricular size (Evans' index) detected early after ETV was associated with satisfactory clinical outcomes (p = 0.02). The incidence of prepontine scarring was observed in all cases of the ETV failure group. A significant risk factor for ETV was the to-and-fro movements of the third ventricle floor after ETV (p = 0.048).

ETV could be a safe and effective treatment option for adult patients with BPC. It is important that prepontine scarring and the to-and-fro movements of the third ventricle after ETV should be confirmed carefully when performing ETV on adult patients with BPC.