PMC3107467_01
Presurgical MRI examinations. A: Head MRI revealing a normal ventricle. B: MRI showing a cystic lesion across the foramen magnum. T2WI imaging showed the lesion as a high signal (arrow). C: T1WI imaging showed the lesion as a lower signal; the cerebellar tonsil was compressed and moved upwards. The pons and cervical spinal cord anterior to the lesion appeared notch-like (arrow). D: MRI showed the spinal cord thickened from the pons to T10; a syrinx can be seen. T2WI imaging appeared as a high signal (arrow).
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F1
The cerebellar tonsil was compressed upwards, the pons and cervical spinal cord appeared notch-like due to the compression of the cyst. The spinal cord was thickened from the pons to the thoracic spinal cord T10, and a syrinx was seen in the spinal cord with a low T1W1 signal and a high T2WI signal. The size of the supratentorial ventricular system was normal (Figure 1).
Results of pathology. H&E staining showing fibrous tissue on the wall of the cyst, and no epithelial cells were observed; arachnoid cyst was diagnosed. Magnification: x200.
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F2
The results of pathological examination showed that the wall of the cyst was composed of fibrous tissue but without epithelial cells; the diagnosis of arachnoid cyst was made (Figure 2).
MRI 3 months after surgery shows the remaining arachnoid cyst (which was slightly smaller than before surgery), the compression on the cerebellar tonsil, the reduced pons and cervical spinal cord. However, the syrinx was the same as presurgery. A: T1WI; B: T2WI.
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F3
Although the compression on the cerebellar tonsil, pons and cervical spinal cord was reduced, the size of the syrinx was still the same as before surgery (Figure 3).