木瓜直播

A device described as an ECG for the eye accurately distinguishes stroke from other causes of dizziness in the emergency department (ED), a small proof-of-concept study showed.

When tested on 12 patients in the ED for acute vestibular symptoms, the device picked out all six vertebrobasilar strokes that were subsequently diagnosed with MRI, David Newman-Toker, MD, PhD, of the Johns Hopkins Hospital, and colleagues reported online in Stroke.

The bedside device feeds webcam video from goggles mounted with an accelerometer to computer software that looks for abnormal corrective eye movements when the head turns.

It replicates the best clinical test for stroke in this setting -- the horizontal head impulse test -- but without the requisite expertise for interpretation that's often not available in the ED.

Rahul Karamchandani, MD, a neurology fellow who has been teaching the clinical head impulse test to residents at the University of Texas Health Science Center in Houston, agreed that the real promise of the device is automated, objective measurement.

"It's a technology that [a person] won't have to be trained on to use," he commented in an interview with 木瓜直播, though noting that current version of the device isn't fully automated.

But full automation is in the works, the investigators pointed out, adding that the device could be used much like an electrocardiogram is for heart attack.

"Widespread use in EDs or urgent care clinics might involve a fully automated eye ECG read by local providers with backup telediagnosis by off-site experts," they wrote.

In the ED, it could be used "to discharge acute vestibular syndrome patients unlikely to have a stroke without any imaging, speed access to acute therapy without awaiting MRI, or select patients for enrollment in treatment trials for acute posterior circulation stroke," they added.

Relying on CT scans misses most ischemic strokes in the first 24 hours, while even MRI won't find about one in five strokes near the brain stem and cerebellum the first day because of lag in structural anatomic changes.

Strokes in these regions of the brain that control functions like balance, coordination, and motor control signaling account for about one-quarter of acute vestibular syndrome cases.

"We're spending hundreds of millions of dollars a year on expensive stroke work-ups that are unnecessary, and probably missing the chance to save tens of thousands of lives because we aren't properly diagnosing their dizziness or vertigo as stroke symptoms," Newman-Toker said in a statement.

His group tested the ICS Impulse device at two tertiary-care centers from 2011 to 2012. The patient population consisted of 12 consecutive adults, seen over a roughly 1-year period in the ED, within 7 days of onset of continuous vertigo or dizziness with pathological nystagmus and at least one other symptom: nausea or vomiting, head motion intolerance, or new gait or balance problems.

Patients were excluded if they were intoxicated with alcohol or drugs, had a relevant vestibular or oculomotor disorder history, or had sustained new head trauma.

All had a diffusion-weighted MRI scan within 10 hours to 5 days after symptoms began. None identified by the device as having a peripheral cause of symptoms had any indication of stroke on imaging.

The head movements used for testing eye movement response with the device weren't a problem for patients in the trial, who had more trouble sitting up than with the test, the researchers noted.

While the interpretation wasn't automated in the study, it could be using a simple stroke diagnosis algorithm requiring either a bilaterally abnormal quantitative horizontal head impulse test or a unilateral abnormal result plus either direction-changing nystagmus or skew deviation, they wrote.

Future versions of the ICS Impulse software will quantify nystagmus and skew deviation, but another similar device (EyeSeeCam) has been developed that already does so, the researchers noted.

The group acknowledged the small sample size, the possibility of false-negative imaging, and that all the investigators and technicians were experienced with the clinical horizontal head impulse test.

Patient selection is also an issue, they noted.

"These results only apply directly to a specific subset of patients with vertigo or dizziness (ie, acute vestibular syndrome). Not all clinicians are familiar with selecting appropriate patients," they wrote. "Use of horizontal head impulse tests in all comers with dizziness, including transient or purely positional symptoms, would markedly increase MRI overuse."

From the American Heart Association:

Comment