Endoscopic Third Ventriculostomy for the Treatment of Chiari I Malformation and Related Hydrocephalus: Clinical Outcomes

7% to 10% Chiari type I malformation (CIM) patients present with associated hydrocephalus. Endoscopic third ventriculostomy (ETV) had been proved to be an effective alternative to shunting procedures in the treatment of obstructive hydrocephalus. Specific research concerning the application of ETV in hydrocephalic patients with concurrent CIM reported that treatment focused on hydrocephalus with ventricle dilation also provides alleviation of CIM and even of syringomyelia. This retrospective study was conducted to analyze the morphological variation and the mutual effect between hydrocephalus and CIM to identify the efficacy of ETV.

Method: Patients treated for symptomatic hydrocephalus associated with CIM by ETV in our single institute from September 2015 until July 2018 were included. Preoperative workup contained physical examinations and magnetic resonance imaging (MRI) (1.5 T). CIM was defined as tonsillar herniation greater than 5 mm below foramen magnum on MRI. None of the patients underwent any cerebrospinal fluid shunt or decompression to relieve the CIM before. Postoperative outcomes were recorded as symptom improvement of hydrocephalus and CIM and imaging changes according to Evan’s Index (EI), third ventricle transverse diameter, fourth ventricle sagittal diameter, extent of tonsillar herniation and syrinx. Statistical analysis was performed using Student’s t-test with significance at p <  0.05.

Results: Eight patients with mean age 39.12 presented with main symptoms of hydrocephalus underwent ETV. Mean tonsillar ectopia was 9.14 mm. Mean postoperative third ventricle diameter was 13.75 mm and significantly smaller than preoperative diameter (p = 0.002). Moreover, fourth ventricle sagittal diameter and EI was significantly lower than that of presurgery (p = 0.041, 0.007, respectively). Signs and symptoms of CIM and hydrocephalus were improved in all patients. Only one patient needed another surgery due to a late closure of the stoma.

Conclusion: ETV is an effective treatment for hydrocephalus associated with CIM.