The baroreflex normally serves to buffer blood pressure against excessive fluctuations. ABF occurs when afferent glossopharyngeal and vagal nerve fibers or their central connections are impaired. ABF is characterized clinically by labile hypertension, episodic tachycardia, and orthostatic hypotension (OH). ABF is rare, but analysis of data from a large referral center for autonomic disorders may allow a better understanding of this syndrome.

We performed a retrospective chart review of all patients who underwent standardized autonomic reflex testing between 2000 and 2020 and had confirmation of the diagnosis of ABF by an autonomic disorders specialist.

A total of 104 patients with ABF were identified. Head and neck radiation was the most common etiology (86.5%) followed by neck surgery (5.8%) and other causes (7.7%). The most common findings were hypertension (87.5%), blood pressure lability (78.8%), OH (91.3%), syncope (58.6%), headache (22.1%), and tachycardia (20.2%). Patients commonly were treated with antihypertensives (66.3%), pressors (41.3%), or both (19.2%). In ABF due to radiation, median latency to symptom onset  was 7.2 years, while in ABF due to surgery, symptoms of ABF started shortly after surgery (median = 0 year [0-2]). Patients with radiation-induced ABF frequently had other radiation-induced complications, including dysphagia (67.8%), hypothyroidism (65.5%), brachial plexopathy (20%), cranial neuropathy (36.6%), and stroke (22.2%). All-cause mortality was 39.4% over a 20-year period.

ABF should be suspected in patients with history of head and neck cancer treated by radiation and/or surgery who present with labile hypertension and OH. The management is challenging and may require the use of both antihypertensive and pressor medications. Patients with radiation-induced ABF often experience multiple other complications of radiation. Further studies are needed to better understand the pathophysiology of ABF.