PMC6786386_01
a Sagittal T2 image of the cervical spine. There is evidence of traumatic occipito-cervical dissociation with significant widening of the basion-dens interval and haematoma at the expected location of the anterior atlanto-occipital ligament. Widening of the condyle-to-C1 interval and C1-C2 interspinous ligament disruption is also observed. A large hyperintense prevertebral haematoma extends from the clivus to C4. Normal position of the cerebellar tonsils has been noted. b Sagittal T2 image of the cervical spine 8 months post injury. There has been interval occipitocervical fixation. There is a sizeable cyst inferior to the clivus and anterior to the apical ligament at the expected location of the anterior atlanto-occipital ligament. There is also marked descent of the cerebellar tonsils by 13 mm, resulting in mild crowding of the brain stem and spinal cord but no focal cord signal change or syringohydromyelia
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Fig1
Injuries at the time of presentation included diffuse axonal injury and complete C1/C2 dislocation (Fig. 1a.). Routine follow-up MRI of the spine at 8 months post SCI demonstrated that the patient had an ACM with tonsillar herniation of ~13 mm into the vertebral canal (Fig. 1b).
PMC6786386_02
a Sagittal T2-weighted image at the time of injury. There is partial transection of the cord at the cervicothoracic junction and extensive cord oedema, with disruption of the posterior longitudinal ligament and ligamentum flavum. No Chiari malformation is present. b,c Sagittal T2- and sagittal T1-weighted images 3 years post injury. Myelomalacia and post-traumatic cyst formation with focal tethering of the cord secondary to dural adhesions at the site of injury. There is tonsillar descent through the foramen magnum of ~10 mm, consistent with acquired Chiari malformation
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Fig2
Imaging at the time of presentation demonstrated cord injury at the cervicothoracic junction (Fig. 2a).
PMC6786386_03
Sequential T2-weighted sagittal images of the cervical spine 12 years post injury demonstrate focal myelomalacia and atrophy at the site of decompression at the C7/T1 level. The cerebellar tonsils extend 10 mm below the level of the foramen magnum consistent with acquired Chiari malformation. Abnormal fluid signal intensity within the spinal cord is seen at the level of C2 consistent with associated syringomyelia
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Fig3
MRI demonstrated tonsillar descent of 12 mm (Fig. 3).
PMC6786386_04
a Sequential sagittal T2-weighted images 15 years post injury acquired following new difficulty in swallowing, double vision and loss of upper limb power bilaterally. MRI demonstrates an acquired Chiari malformation with a tonsillar descent of 12 mm, interstitial spinal cord oedema and mild syringomyelia extending from C2 to C4. There is evidence of previous cord injury at the T3 level with local dural tethering. b Cordectomy has been performed at the level of T1. There has been interval resolution of the altered cord signal cranial to the cordectomy and resolution of the acquired Chiari malformation with no significant tonsillar descent. Subcutaneous pseudomeningocele at the laminectomy site at T2 has been noted
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Fig4
MRI at this time demonstrated an ACM with tonsillar descent of ~12 mm (Fig. 4a).