Dorsal dermal sinus

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Dysplastic deformed cerebellar tonsils extend through the foramen magnum to the lower margin of the second vertebra body consistent with a Chiari malformation, with associated fourth ventricular descent and small volume posterior fossa. The spinal canal is capacious, and vertebral alignment, height, and marrow are normal.

Spinal dysraphism with bony deformity of the dorsal elements, lamina, and spinous processes involving C6 and, to a lesser extent, the adjacent dorsal elements of C5 and C7. The dorsal spinal cord is tented to the dorsal defect, through which a tubular defect consistent with a dermal sinus passes into the subcutaneous tissues, which are markedly thickened at this site. The tented portion of the cord is of abnormal signal and in continuity with focal syringomyelia, which extends from C4 to C6.

From the superior border of the syrinx cavity a more linear cleft of CSF signal extends superiorly to the C2/C3 disc level, with areas of myelomalacia to either side. This latter appearance raises the possibility of a partial split cord. The cord below the spinal dysraphism is normal.

Thoracic and lumbar spine (not shown) demonstrate only multilevel degenerative changes. The conus terminates at L1.

Conclusion:

Chiari malformation, cervical spinal canal dysraphism, with a dorsal dermal sinus, cord deformity and tethering, and syrinx cavity. The more linear cleft of CSF from anterior to posterior surfaces of the cord above the cyst suggests a partial diastomatomyelia associated with the dorsal defect.