F24 Hindbrain herniation in hypermobile Ehlers-Danlos syndrome patients.
A large proportion of patients suffering from the hypermobile Ehlers-Danlos syndrome (EDS) also show an element of hindbrain herniation, often labelled as a Chiari malformation.
120 consecutive patients with hypermobile EDS had MRI scans of the cervical spine and craniocervical junction, performed in an upright MRI scanner, where the cervical spine angle was measured with the cervical spine in neutral, flexion and extension and compared with a group of normal individuals. Any instability of the cervical spine was recorded. The presence or absence of the atlanto-axial instability was also recorded. The presence or absence of hindbrain herniation was also recorded.
The majority of patients (80%) showed an increase in the cervical spine angle in neutral, which was 20% greater than that seen in the normal group. Fifty percent showed a greater ability to flex their neck and 45% had a greater angle in extension. Instability of the cervical spine was seen in 72% and 80% showed an element of instability of the atlanto axial joint. Evidence of cerebellar tonsillar ectopia greater than 5 mm through the foramen magnum was noted in 43%, with no evidence of syringomyelia. The pattern of hindbrain herniation was distinctly different from that seen in patients suffering from the Chiari syndrome. In the patients suffering from EDS, the herniated tonsils appear more rounded and are more laterally situated within the foramen magnum, when compared to patients with true Chiari syndrome, where the herniated tonsils lie more medial and are pointed in shape. Evidence of hindbrain herniation is seldom seen in the midline sagittal sections of an MRI scan.
With hindbrain herniation being more frequently seen in patients with EDS, it is important that the pattern of herniation is described differently from the Chiari syndrome, to avoid confusing the two different conditions.
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