Intraoperative Ultrasonography for Definition of Less Invasive Surgical Technique in Patients with Chiari Type I Malformation

Abstract

INTRODUCTION: Chiari malformation type I (CM) is the main congenital malformation disease of the craniovertebral junction. The ideal surgical treatment is still controversial. Invasive procedures inside the cerebrospinal fluid (CSF) space and associated with dural repair are considered the gold standard; however, less invasive surgery with isolated bone decompression without dural opening may be possible in selected patients. Our study evaluates the efficacy of intraoperative CSF flow measurement with ultrasonography (USG) as a determining parameter in the selection of these patients. METHODS: We analyzed prospectively 49 patients with CM operated on at the Hospital das Clinicas, College of Medicine, University of Sao Paulo. Patients underwent decompressive surgery with or without opening of the dura mater after intraoperative USG measuring flow rate. A value of 3 cm/second was considered a cutoff. Quality of life before and after surgery and the improvement of neck pain and headache were evaluated. RESULTS: Among 49 patients enrolled, 36 patients (73%) had CSF flow >3 cm/second and did not undergo duraplasty. In 13 patients (27%) with initial flow <3 cm/second, dural opening was performed together with duraplasty. All patients improved when preoperative and postoperative scores were compared, and all clinical parameters evaluated did not differ between both surgical groups. Patients submitted to bone decompression alone had a lower complication rate. CONCLUSIONS: Intraoperative USG with measurement of CSF allows the proper selection of patients with CM for less invasive surgery with bone decompression without duraplasty.