1. A sagittal T2-weighted MRI of a six-month-old shih-tzu demonstrating a large hyperintense fluid accumulation located in the mid-line, dorsal to the midbrain, rostral to the cerebellum and caudal to the occipital lobes.
A sagittal T2-weighted MRI of a six-month-old shih-tzu demonstrating a large hyperintense fluid accumulation located in the mid-line, dorsal to the midbrain, rostral to the cerebellum and caudal to the occipital lobes. The imaging appearance is consistent with a quadrigeminal cyst compressing the occipital lobes. The percentage compression of the occipital lobes is calculated by drawing a line between the point where the cerebral cortex and the fila olfactoria join (marked A) and the tip of the osseous tentorium cerebelli (marked C). Distance B to C represents the diameter of the cyst. The percentage compression is expressed as: Percentage occipital compression=distance BC / distance AC x 100 In this case, the percentage compression is 27 per cent. Compression of more than 14 per cent is thought to result in seizure activity and this dog did suffer seizures
Mark Lowrie In Practice 2014;36:30-36
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