PMC8247923_01
MRI cervical spine T2-weighted sagittal image.
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F1
The preoperative cervical MRI T2-weighted study showed a Type I Chiari malformation and syrinx (i.e., cerebellar tonsillar herniation up to the C1 level, diffusely dilated central canal from C5 to D3, and nonenhancing hyperintensity, present in the upper cervical cord [Figure 1]).
Diagrammatic representation of the first view after dural opening during surgery. PICA: Posterior inferior cerebellar artery, CNXI: Spinal accessory nerve.
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F2
Further, at the level of the foramen magnum, the left XI cranial nerve was severely compressed between the left-sided herniated tonsil and posterior inferior cerebellar artery (PICA) [Figure 2].
Diagrammatic representation of view after subpial resection of the left tonsil showing CNXI running just above the PICA, PICA: Posterior inferior cerebellar artery, CNXI: Spinal accessory nerve.
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F3
After subpial resection of the left tonsil [Figure 3], a muscle patch was interposed between the XI cranial nerve and PICA.