182 Deep Brain Stimulation (DBS) Surgery for Treatment-resistant Hypertension

Abstract

INTRODUCTION: Hypertension is a disease that affects approximately one billion people worldwide. It is estimated that as much as 5 to 30% of the hypertensive population are resistant. We present the first case of a hypertensive patient on quadruple medical therapy whose blood pressure was controlled with DBS of the ventral lateral periaqueductal grey (vlPAG); this led us to test out the stimulation effects in reverse translational studies. METHODS: A 55-year-old man developed an ischaemic internal capsular stroke. In the peri-stroke period, blood pressure readings ranged from 265/96 to 153/89 mm Hg and antihypertensive medication was prescribed: atenolol, diltiazem, perindopril and indapamide. Four months later, subsequent to multiple dose increases in the quadruple therapy, his blood pressure ranged from 153/87 to 134/72 mm Hg. Later when he developed post stroke pain, we implanted a DBS quadripolar electrode into the vlPAG which is a recognized target for treating refractory pain. RESULTS: Pain levels decreased initially but returned to pre-surgical levels at 4 months. Immediately after DBS, there was a gradual decrease in blood pressure that prompted withdrawal of all antihypertensive medications. At 27 months, DBS off-switching increased blood pressure by 18/5 mm Hg (P = 0.01) and during subsequent on-switching the blood pressure decreased by 33/13 mm Hg (P = 0.01). These effects were repeatable. Concomitant serum levels of cortisol and adrenaline did not show any significant differences. At 5 years post-surgery, the patient now remains on a single anti-hypertensive agent (Perindopril 4mg) with his blood pressure readings on ambulatory monitoring ranging from 110 to 125/60 to 85 mm Hg. DBS effects were compared in a group of normotensive and spontaneously hypertensive rats (SH). In hypertensive rats low frequency PAG stimulation results in a depressor response resulting in a significant drop in arterial pressure suggesting sympathoinhibition; in contrast such a response was lacking in normotensive rats. We would also like to present muscle sympathetic nerve activity (MSNA) measured at 5 years. CONCLUSION: Low frequency vlPAG stimulation has resulted in controlling refractory hypertension in a patient previously on multi-drug therapy. Experiments in hypertensive and normotensive rats have confirmed physiological findings in patients and provided further validation of this therapy.