HTN and shift of CPP auto-regulatory curve

Q: Patients with chronic hypertension, may tolerate higher cerebral perfusion pressure (CPP) as their autoregulatory curve may have been shifted to the? (select one)

A) right 
B) left


Answer: A

High CPP leads to hypertensive encephalopathy and consequently to cerebral edema due to the eventual breakdown of autoregulation. But patients with previous chronic hypertension have their autoregulatory curve shifted to the right, and can tolerate higher CPP in comparison to other patients. The limit to this threshold in hypertensive patients is found to be around CPP of 120 mmHg.

#neurosurgery
#neurology



References:

1. Strandgaard S, Paulson OB. Cerebral blood flow and its pathophysiology in hypertension. Am J Hypertens 1989; 2:486.

2. Lassen NA, Agnoli A. The upper limit of autoregulation of cerebral blood flow--on the pathogenesis of hypertensive encepholopathy. Scand J Clin Lab Invest 1972; 30:113. Kaplan NM. Management of hypertensive emergencies. Lancet 1994; 344:1335.