Introduction: The authors discuss the utility and clinical implications of intraoperative MRI (iMRI) in the selection of patients for duraplasty after bony decompression of Chiari I malformation.
Methods: Adult patients (18 years old and older) with symptomatic Chiari 1 malformations undergoing suboccipital craniectomy with or without cervical laminectomy were identified from the senior author’s operative log. The utility of iMRI to evaluate the need for duraplasty was investigated. Demographics, clinical presentation, operative times, foramen magnum dimensions on midsagittal T2 MRI, complications and outcomes were analyzed between patients whose surgeries were completed with the aid of iMRI and those performed without intraoperative imaging.
Results: 18 patients were identified for this study. 9 patients were selected for iMRI and 9 underwent standard surgical intervention without intraoperative imaging. 7 of the 9 patients in whom iMRI was performed received duraplasty (77.7%) after iMRI demonstrated concern for inadequate decompression in comparison to duraplasty in 100% of the patients undergoing standard decompression. Midsagittal T2 sequences through the foramen magnum of pre, intra and postoperative MR images demonstrated consistent enlargement in all measured dimensions (clival-spinomedullary interval, post-tonsillar interval and total foramen magnum diameter). The use of iMRI led to increased surgical time but no significant change in the length of hospital stay. Surgical outcomes were comparable between groups. There was one surgical complication resulting in paraplegia in a patient undergoing iMRI believed to be secondary to a thoracic spinal cord infarction while under general anesthesia.
Conclusions: Overall, the rate of duraplasty was reduced by 22.3% by integrating the use of iMRI to determine the need for duraplasty following bony decompression. Surgical outcomes were equivalent between groups. The data herein support the benefit of iMRI for intraoperative decision making regarding the need for duraplasty in the setting of Chiari I malformation.
Patient Care: The authors present the first case series highlighting the use of intraoperative MRI for decompression of Chiari I malformation. There are obvious benefits to bone only decompression when compared to duraplasty and assessing the need for augmentation duraplasty following bony decompression may identify a subset of patients in whom duraplasty is unnecessary.
Learning Objectives: By the conclusion of this session, participants should be able to describe the utility of intraoperative MRI in the setting of Chiari decompression to assess the need for duraplasty following bone only decompression