What is the relationship of changes in blood pressure to CNS disease?
Lesions of the hypothalamus and medulla oblongata or tumors of the posterior fossa may cause arterial hypertension. Ischemic, degenerative, or destructive lesions of the NTS in the medulla may result in chronic lability of blood pressure.
Cushing’s response of hypertension, bradycardia, and apnea, an important sign of increased intracranial pressure and potential herniation, also may develop after ischemic lesions of the dorsal medullary reticular formation along the floor of the fourth ventricle.
Hypertension caused by posterior fossa tumors is due to the compression of the pressor center at the rostral ventrolateral medulla (RVLM).
Such an increase in blood pressure may present as malignant hypertension and may be indistinguishable from a pheochromocytoma.
Patients with normal pressure hydrocephalus also may have chronic hypertension.
Decreased blood pressure is rare with CNS disease, but orthostatic hypotension may accompany brain stem tumors, although the exact mechanism and the specific nuclei involved are not clear.