Factors which affecting the success of endoscopic third ventriculostomy

Objective: Endoscopic third ventriculostomy (ETV) has been increasingly used for the treatment of obstructive hydrocephalus over the last 17 years in our departmant. The objective of this study is to determine if demographic, etiologic, radiologic and operative factors correlate with low success rate of ETV in the treatment of hydrocephalus. Materials and Methods: A retrospective review was performed of 88 patients undergoing ETV between January 2010 and February 2015 at Ege University School of Medicine, Department of Neurosurgery. In this study, we were careful when selecting patients. According to this, patients were exculuded from the study if they had cranial surgery, including external ventricular drainage, ventriculoperitoneal shunt insertion, previusly performed ETV and they had intracranial lesion. Information was obtained from patients' medical records, radiological records [Magnetic Resonance Imaging (MRI)], operative reports and ETV procedure videos. We analysed the influence of the following factors on the success rate of ETV; patient, age (divided into five groups: 0-1 month, 1-6 months, 6-12 months, 1-18 years, adult), symptom, etiology of hydrocephalus (inflammatory and mechanical), preopeative MRI ( tuber cinerum depression, flow artifact, optimal entry point and trajectory for ETV), postoperative MRI (tuber cinerum depression, flow artifact, entry point and trajectory for ETV used by surgeon, parenchymal hemorrhage), ETV procedure video (relative size of ostium as the percentage of ostium area to the triangular area between corpus mamillares and infundibulum, hemorrhage, venous angle and forniks damage), peroperative complication (minör and majör hemorrhage), postoperative complications (CSF leak, infection, hematoma). Successful ETV was defined as resolution of the patient's symptoms, no need for shunt in a long term, in the presence of CSF flow through the stoma on cerebrospinal fluid (CSF) flow MRI and Three-dimensional (3D) constructive interference in steady state (CISS) MRI. Analysis was performed using Chi-Squared test, Paired samples T test, Independent samples T test. Results: In our series of 88 ETV procedures with a follow-up of at least 3 months. The mean follow-up was 20.9 months (range 3 months – 4.5 years). There were 48 (54.5 %) females and 40 (45.5 %) males. The mean age at operation was 17.8 years (range: 11 days – 71 years). 28 patients were above age of 18 years (31.8 %) (mean age: 44.8 years) and In the large group of patients (60 patients, 68.2 %) who were between age of 1 year and 18 years, the mean age was 66 months. Most commonly symptom was headache (48.9 %), etiology was aqueduct stenosis (85.2 %).complication was hemorrhage (33 %). The mean perpendicular distance from the ideal entry point to the midline was 24.3 mm. and the mean perpendicular distance to the coronal suture was 10.9 mm. The mean perpendicular distance from the surgen's entry point to the midline was 29 mm. and the mean perpendicular distance to the coronal suture was 11.5 mm. The optimal entry angle according to the anterior-posterior plane was 87.8°, According to the lateral plane was 88°.The values used in the operation were according to the anterior-posterior plane was 90° and 88.1°. Mean relative size of ostium was 13,8 % (range: %2 - %49). Success rate of ETV was 0 % in 0-1 month group, 28.6 % in 1-6 months group, 28.6 % in 6-12 months, 73.9 % in 1-18 years group, 85.8 % in adult group, 70.5 % in over all. ETV failure time was mean: 85 days (range: 1 day - 396 days). There was no significant difference in the location of the optimal entry point and surgen's entry point (p: 0.69) and there was no significant difference in optimal entry angle and The values used in the operation (p: 0.59, p: 0.18). CSF leak, 0-1 month and 0-6 months age groups had a statistically significant higher risk of ETV failure (p: 0.001, p: 0.002, p: 0.003). Interestingly, we were unable to demostrate a correlation between ETV failure and mean relative size of ostium (p: 083), peroperative hemorrhage (p: 0.32), tuber cinerum depression (p: 0.24). Discussion: ETV as an alternative to ventriculoperitoneal(vp) shunting has become more important over the last 20 years, as long-term reliability of a vp-shunt is disappointing due to multiple malfunctions, such as mechanical failure and infection (59, 60). It is well-described in the literature that age is an important factor in the failure and long-term reliability of ETV, with reliability being lower in very young children (61, 62, 63, 64, 64, 65). We also recorded a higher failure rate. The fact that Our patients show the higher failure rate in children with inflammatory etiology. These results are identical to the literature (65). In our study, there was no significant difference between ETV failure and regression in tuber cinerum depression. This information is inconsistent with the literature (72, 73, 74). There was no significant difference in the location of the optimal entry point and surgen's entry point ( except, the distance to coronal suture; 4.7 mm.) and there was no significant difference in optimal entry angle and the values used in the operation. These results indicate that surgical experience is important and navigation methods are not absolutely necessary. CSF leak developed due to the difference in pressure causes ETV failure. These results are identical to the literatüre (84, 85, 86). In contrast, we were unable to find a correlation between mean relative size of ostium and ETV success. This interensitng result is parallel with single study in the literature data (81). From our data, ETV appears to be a safe and effective means of managing hydrocephalus. ETV failure is an expected result as an ETV success and we are trying to make it perfect. We think that patient selection and surgical experience are increase the success rate of ETV.