Neurosurgery
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Operations on the 4th ventricle offer the potential for injury of the brain stem, cerebellum, cranial nerves, and major cerebellar arteries and veins. Twenty-five cadaver brains were examined using 3x to 25x magnification to define the relationship of these vital structures to the 4th ventricle. The 4th ventricle has a roof, a floor, and two lateral recesses. ⋯ The lateral recesses and adjoining parts of the roof and floor are intimately related to the cerebellopontine fissures, the anterior inferior cerebellar arteries, and the veins of the cerebellopontine fissure. The cerebellar peduncles converge on and form a major part of the ventricular surface. The hili of the dentate nuclei abut on the superolateral recesses of the ventricle near the superior poles of the tonsils.
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Patients with ankylosing spondylitis frequently experience back pain and they have a well-known propensity for spinal fractures, but they rarely manifest motor and sensory nerve root impairment. We recently encountered a patient with ankylosing spondylitis who complained of classical spinal claudication with urinary sphincter dysfunction. Computed axial tomography revealed marked lumbosacral lateral recess and foraminal spinal stenosis that was not evident on the myelogram; at operation the stenosis appeared to be the result of extensive posterior soft tissue ossification. This heretofore unrecognized yet potentially treatable complication of ankylosing spondylitis is discussed.