Researchers have found a promising new way to predict which patients with a congenital brain malformation would respond well to surgical intervention. The results of this preliminary application of a non-invasive advanced imaging approach, which were published this month in the Journal of Neurosurgery, could significantly improve the quality of care for patients with Chiari malformation type-I (CM-I), a congenital condition in which the lower part of the cerebellum bulges through the normal opening at the base of the skull and into the spinal canal.
Although a congenital condition, many people don’t begin to experience symptoms such as headaches, dizziness, impaired balance and more, until adulthood. Surgical intervention is successful in about 75% of cases but because of the risks associated with the surgery, an effective way to identify the conditions that would predict positive surgical outcomes is vital.
The study was conducted by a team working through the Center for Systems Imaging Core at Emory University and led by John Oshinski, professor of radiology & imaging sciences and biomedical engineering, Dan Barrow professor of neurosurgery, and Grace McIlvain, now an assistant professor of biomedical engineering and radiology at Columbia University.
Measuring Brain Motion and Cerebrospinal Fluid Flow
The researchers tested two measures. They first used phase-contrast magnetic resonance imaging (MRI) to measure cerebrospinal fluid (CSF) flow/stroke volume, which is the amount of cerebrospinal fluid passing through the cerebral aqueduct during a heart cycle. CM-I obstructs normal flow, causing pressure variations in and around the intracranial space. This impaired CSF flow also increases brain motion, as brain tissue tries to displace CSF to maintain cerebral homeostasis. The researchers measured brain motion using a technique called cine displacement encoding with stimulated echoes (DENSE) in MR imaging. DENSE can quantify submillimeter displacements associated with brain tissue motion. They also assessed tonsillar descent, or the amount of the lower part of the cerebellum that descends into the spinal canal. This measure has previously been used as a standard clinical presurgical assessment metric but has produced mixed results.
Promising Results
The researchers found that presurgical measures of cerebral dynamics were more predictive of improvements to CSF flow and brain motion after surgery than the conventional measure of presurgical tonsillar descent.
“The measurement of neural dynamics such as brain motion and CSF flow, rather than static markers such as tonsillar descent, are a new approach to understanding the pathophysiology of brain disease, and represent a new method to improve patient treatment options,“ says Oshinski.
The next step is to validate the work through a larger, blinded clinical trial, the work for which is already underway as the team recruits additional sites for clinical trials.