Impaired CSF flow may occur when the borders of the foramen magnum are impinged upon by low hanging or ectopic cerebellar tonsils and brainstem, effectively acting as a cork-stopper and potentially restricting normal flow of CSF between the 4th ventricle and central canal of the spinal cord, as well as the extraventricular CSF flow between the intradural cranium and spinal canal. Although a commonly used radiological definition for Chiari malformation Type I (CMI) is a 5mm descent of the tonsil below the foramen magnum, the threshold has not been validated in the context of CMI symptoms, CSF flow alteration, or the nature and degree of misalignment of the upper cervical vertebrae. The use of MRI cine sequences and software allow for the observation of diminished or absent flow in the retrocerebellar spaces and the 4th ventricle and between the brainstem and the cerebellum, and this allow for greater insight into anatomic and functional relationships that may bring greater insight to symptomatic CMI.
To use 3 cine Phase Contrast MRI sequences of the upper cervical spine and head to evaluate tonsillar station, CSF flow, and upper cervical alignment in patients with a history of chronic head and neck pain after spinal trauma. The same imaging is performed before and after provision of upper cervical correction of misalignment via Image Guided Atlas Treatment (IGAT®).
Pre and post CSF flow and tonsillar station was evaluated using FONAR® UPRIGHT MRI CSF phase contrast sequence cine phase contrast scans. The scans employ phase contrast RF-spoiled gradient echo sequence with TR = 19-22 ms, TE = 9-12 ms, slice thickness = 8 mm, flip angle = 20-25°, matrix = 256×128 zero filled to 256×256, and NEX = 2. Data acquisition was retrospectively gated using ECG or pulse oximeter covering the entire cardiac cycle. Thirty-two (32) uniformly spaced time frames were obtained by linear interpolation in post-processing.
Proton Density sequences were used in the sagittal, axial and coronal planes to permit visualization of cerebellar tonsils in relation to the foramen magnum. Misalignment of the upper cervical spine was assessed using protocol set for in Image Guided Atlas Treatment (IGAT®). Correction was performed using the Atlas Orthogonal Instrument utilizing a vector determined with IGAT®. Post correct CSF Cine sequences were obtained for review. The pre- and post-treatment scans are presented for 3 patients.
Post correction CSF Cine sequences indicated improved CSF flow as well as improved alignment of the boney structures at the craniocervical junction. These findings are consistent with the results of placebo controlled study.
Correction of upper cervical misalignment may improve CSF flow via hypothetical mechanisms requiring further investigation.