martedì 2 ottobre 2007

Spinal meningioma


Sagittal T1 and T2 sequences demonstrate an intradural extramedullary lesion in the midthoracic region which is soft tissue signal on T1 (Figure 1) and soft tissue signal on T2 (Figure 2). Sagittal T2 images demonstrate CSF capping above and below the lesion, which suggests an intradural extramedullary location.
Post contrast images demonstrate homogeneous enhancement of the lesion (Figure 3). A “dural tail” demonstrating the characteristic broad based dural attachment on post gad images is shown.
Incidentally, multiple hemangiomas are demonstrated on sagittal T2 images (Figure 2).

Diagnosis: Spinal meningioma

When evaluating lesions of the spinal cord, it is important to first determine in which space the lesion is located. Lesions may be intramedullary, intradural extramedullary, or extradural.

Meningiomas are the second most common tumor in the intradural extramedullary compartment (nerve sheath tumors most common). Meningiomas account for around 25% all spinal tumors and usually occur in the thoracic spine (80%). 15% of spinal meningiomas occur within the cervical spine. Occasionally, they may be purely extradural, or bridge both the intradural and extradural compartments.

Spinal meningiomas are usually located lateral or dorsolateral in the spinal canal. Since they are thought to arise from arachnoid cluster cells, their location is at the entry zone of nerve roots or the junction of dentate ligaments and dura mater. The spinal cord is usually compressed and displaced away from the lesion.

MR usually demonstrates an intradural extramedullary location. The lesions are usually isointense to the spinal cord on T1 and T2 or alternatively hypointense on T1 and hyperintense on T2. Immediate, homogeneous contrast enhancement is characteristic. Calcification may be seen. Most spinal meningiomas demonstrate broad-based dural attachment, and may show a “dural tail,” as in this case. The subarachnoid space above and below the lesion is widened, described as CSF “capping” of the lesion from below and above. This finding is important in confirming an intradural extramedullary location.

The mainstay of treatment is surgical resection, depending on the extent of the lesion. When complete resection is not possible, post-operative radiotherapy may be performed. Monitoring of symptoms is important following treatment.

Differential diagnosis for each spinal compartment

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