By Nancy Walsh
British researchers have successfully treated refractory hypertension with deep brain stimulation, opening the door to a new approach to managing this difficult — and not uncommon — condition.
The finding was serendipitous, explained Nikunj K. Patel, MD, of the University of Bristol, and colleagues in the Jan. 25 issue of Neurology.
The patient, a 55-year-old man, had had an ischemic stroke. While he was in the hospital, his blood pressure fluctuated from 153/89 mm Hg to 265/96 mm Hg, and quadruple antihypertensive therapy was begun, with daily atenolol (50 mg), diltiazem (240 mg), perindopril (4 mg), and indapamide (1.25 mg), the doses of which were increased over the following several months.
The sequelae of his stroke resolved, but he then developed a persistent, severe, left-sided central pain syndrome.
The pain was resistant to conventional treatment, and because deep brain stimulation has been helpful in some cases of chronic central pain, the patient was referred to Patel’s neurosurgery center for treatment.
Patel’s group used a stereotactic technique, guided by magnetic resonance imaging, to target the area of the brain known as the ventrolateral periaqueductal gray/periventricular gray (PAG/PVG), which is associated with analgesic responses.
The patient’s pain decreased, and so did his blood pressure — plummeting to 80/53 mm Hg on the quadruple antihypertensive regimen.
The blood pressure medications were withdrawn, and for the subsequent eight weeks the patient’s blood pressure remained at about 110/65 mm Hg.
At 12 weeks there was a slight increase in pressure, to 124/76 mm Hg, and the patient was given perindopril, 4 mg, with indapamide, 1.5 mg.
The antihypertensives were again withdrawn at 27 months, and at 33 months his blood pressure was 118/70 mm Hg.
Pain was initially improved but returned to preprocedure levels at 4 months; hypertensive control was not linked to pain control, according to the investigators.
“With hypertension in so many patients being resistant to multiple drug therapy, alternative strategies are needed,” the researchers observed.
“The present data and those of others indicate that manipulating the autonomic nervous system is a powerful approach for chronic control of hypertension in humans,” they wrote.
They noted that their study provides class IV evidence (the weakest level of evidence based on a case report) for the use of deep brain stimulation in patients whose hypertension fails to respond to medical therapy.
Animal studies have suggested that stimulation with a 10 Hz frequency — as was used in this patient — could induce both analgesia and hypotension through excitatory effects on the PAG/PVG neurons.
Various neuronal structures adjoining ventrolateral PAG, such as the rostral ventrolatral medulla and locus cereleus, may be involved in the hypotensive response to deep brain stimulation in an inhibitory manner, Patel and colleagues expained.
In addition, that response may result from alterations in cerebral perfusion and decreases in sympathetic neuronal activity.
Deep brain stimulation of the PAG/PVG, Patel’s group concluded, “provides an opportunity to elucidate central mechanisms controlling blood pressure in patients with refractory hypertension.”
Reviewed by Dori F. Zaleznik, MD; Associate Clinical Professor of Medicine, Harvard Medical School, Boston and Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner.