Conference Coverage

Judicious EEG use identifies pseudosyncope during tilt-table testing



Limiting EEG during tilt-table testing to suspected pseudosyncope cases – instead of the common approaches, no EEG or EEG in everyone – greatly increases the chance of detecting the condition, according to an investigation from Vanderbilt University, Nashville.

Dr. Italo Biaggioni

Dr. Italo Biaggioni

Pseudosyncope, also known as nonsyncopal fainting (NSF), is a conversion disorder where people appear to faint, but don’t lose consciousness. It’s generally thought to be a physical manifestation of traumatic stress. Patients “aren’t faking it; they believe they are fainting,” said senior investigator Italo Biaggioni, MD, a professor of medicine and pharmacology at the university and director of the Vanderbilt Autonomic Dysfunction Center.

It’s “not benign. These patients stop working, stop driving, and need to depend on other people. They can have very dramatic episodes and hurt themselves” when they fall. “They are very disabled,” he said.

NSF is often misdiagnosed and mistreated, and sometimes unrecognized for years. Almost a third of the 39 NSF cases in Dr. Biaggioni’s series, for instance, were on anticonvulsants, and several had undergone cardiac catheterization. Often, NSF is treated as vasovagal syncope, but patients don’t respond to medications. A better way to identify it is needed. “By the time we get them, they’ve been through a lot.” Dr. Biaggioni said at the joint scientific sessions of the American Heart Association Council on Hypertension, AHA Council on Kidney in Cardiovascular Disease, and American Society of Hypertension.

He and his team had a hunch that judicious use of EEG would help, so they limited EEG to suspected NSF cases in a series of 107 refractory syncope patients referred to Vanderbilt for head-up tilt-table testing; 39 (36%) had normal EEGs during an apparent loss of consciousness, as opposed to the slow-wave pattern of true loss of consciousness, and were diagnosed with NSF.

The 36% identified was a marked increase in incidence over more common approaches. Among 64 patients who had tilt-table testing without EEG at Vanderbilt, for instance, three (5%) were diagnosed with NSF. Historically, tilt table plus EEG in all comers has a diagnostic yield of around 18% for the condition. In short, “elective EEG monitoring during tilt-table testing” better “distinguishes between syncope” and NSF, the team concluded.

NSF is suggested by a history of more than 20 episodes of apparent fainting; episodes once a week or more; or losing consciousness for more than 5 minutes. Fainting with eyes closed, or while supine, is also suggestive.

The elective approach prevents inappropriate treatment but is also therapeutic in itself. “When we document with EEG that patients are not really fainting, and explain that to them, it automatically reduces the number of episodes,” Dr. Biaggioni said.

It also saves NSF patients from a nitroglycerin challenge and repeat tilt testing, which is the default in many places when the first round of testing doesn’t trigger an episode. Challenge testing provokes vasovagal syncope in around 10% of even healthy people, so it puts NSF patients at risk for a false positive. As a rule, “we don’t use provocative agents when we [suspect NSF],” he said.

In addition to the 39 NSF cases, 11 patients in the series were diagnosed with vasovagal syncope, and testing didn’t provoke an event in 57 (53%), which isn’t uncommon.

Baseline blood pressure and heart rates were similar across the three groups, and there were more women than men in each. Subjects were in their early 40s, on average.

NSF patients were more likely to be taking anxiety and depression medications. One NSF patient had posttraumatic stress disorder, and two had sexual abuse histories, compared with none in the nondiagnostic and vasovagal groups. The NSF group had a shorter time to an event: 9 minutes versus 19 minutes among vasovagal patients.

Tilt-table testing was done after 6 hours of fasting, and the team used standard 22-channel EEG. Cognitive-behavioral therapy is the go-to treatment for NSF, Dr. Biaggioni said.

There was no industry funding, and the authors didn’t have any disclosures.

SOURCE: Muldowney JA et al. Joint Hypertension 2019, Abstract P3061.

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