case studies

Spinal Dysraphism Diastematomyelia

Introduction
MRI is now the modality of choice for imaging the spine over CT and myelography. Its multi-planar capabilities enable lesions to be diagnosed in three imaging planes sagittal, coronal and axial. Improved surface coils and faster gradients have increased resolution and scanning times to make MRI of the spine a valuable imaging tool. Diastematomyelia is a spinal dysraphism with partial or complete sagittal spinal cord cleft. The presence of a tethered cord can be clearly seen on T1W images that can highlight associated abnormalities such as an intradural lipoma.

Patient History
This is a 47 year old man with known “spina bifida”, with weakness in the legs and numbness in the groin. He had a history of previous myelography and associated tests at a young age. This patient was referred for MRI of the lumbar spine to assess spinal cord and presence of pathology.

Methodology
Sequences used:
T1W sagittal Turbo spin-echo: Pre and Post Gadolinium (fig 1)
T2W sagittal Turbo spin-echo (fig 2)
T1W axial Turbo spin-echo - Pre + Post Gadolinium (fig 3)
T2W axial Turbo spin-echo (figs 4 and 5)
Scanner: Siemens Magnetom Symphony 1.5 Tesla
Coil: CP Spine Array (S3-S6)


Report
There is a loss of signal of the L5/S1 disc due to dehydration. Mild posterior disc bulge is present at this level. The lower lumbar sacral spinal canal and thecal sac are enlarged with abnormal fusion of the laminae at L4 and L5.

There is evidence of a low-lying tethered cord. There is evidence of diastematomyelia with deviation of the cord by a septum that enhances with contrast media. An area of altered signal within the left component of the divided cord with two small T1W high signal foci posterior to this are in keeping with small lipomas.

The altered signal within the left component of the cord may be due to a syrinx cavity, but the presence of a small dermoid cannot be excluded.

Conclusion
There is evidence of spinal dysraphism (i.e. diastematomyelia) involving the lumbar cord with evidence of a low-lying tethered cord.

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