Neurogenic hypertension related to vascular compression of the lateral medulla.

Neurogenic hypertension may be reproduced consistently in experimental animals, although its clinical significance is unclear. An ectatic loop of the posterior inferior cerebellar (PICA) compressed the left vagus nerve root entry-exit zone in two patients with long-standing hypertension. When this loop was mobilized for occipital-PICA bypass, the hypertension resolved. These observations suggest that neurovascular compression of the area encompassing the nucleus tractus solitarius may be a sufficient cause of neurogenic hypertension in humans. The structural and functional relationships of these areas of the brain stem and their role in modulating blood pressure are reviewed.