Evaluation of third ventriculostomy outcome by measuring optic nerve sheath diameter in adult hdyrocephalus.

Objective: It is difficult to demonstrate the success of the procedure in patients with third ventriculostomy. We evaluated that optic nerve sheath diameter (ONSD) measurement, which can reflect intracranial pressure, may be a criterion for decision of endoscopic third ventriculostomy (ETV) success.

Methods: 28 adult patients suffering long overt standing ventriculomegaly (LOVA) who performed ETV were included in this retrospective study. The patients were divided into two groups as successful (group A) and failed ETV group (group B) according to their postoperative evaluation. ONSD was measured on pre- and post-operative computed tomography (CT) and Evan's index (EI), diameter of third ventricule (V3), the patency of ETV stoma and periventricular edema were evaluated by magnetic resonance imaging (MRI).

Results: The mean ONSD was measured as 6.39±0.92mm for the right eye, 6.50±0.91mm for the left eye on preoperative CT. The mean ONSD by CT (after surgery) was 4.89±0.87mm for the right eye, 5.02±0.1mm for the left eye (p<0.05). Postoperative group A and group B were compared according to ONSD measurement; mean ONSD in group A was 4.52±0.69mm for the right and 4.59±0.9mm for the left, mean ONSD in group B was 5.82±0.51mm for the right and 6.1±0.32mm for the left (p<0.05). The best ONSD value for detecting failed ETV was 5.40mm (sensitivity 90%, specifity 75%, AUROC 0.938) for right and 5.91mm (sensitivity 90%, specifity 75%, AUROC 0.950) for left. EE was measured as 0.39±0.12mm on preoperative MRI and 0.39±0.12mm on postoperative MRI (p=0.3). V3 was measured as 14.7±2.47mm on preoperative MRI and 10.47±1.99mm on postoperative MRI (p<0.05).

Conclusion: The statistical values obtained from study show that the ONSD measurement can help in the postoperative evaluation of patients, who had a ETV surgery.