Head-Impulse Tests Not Reliable for Diagnosing Vestibular Disorders

By Marilynn Larkin

May 01, 2019

NEW YORK (Reuters Health) - The risk of misdiagnosis and associated under- or overtreatment of vestibular disorders cannot be reliably estimated by head-impulse tests (HITs), an analysis of available diagnostic studies revealed.

Vestibular disorders generally are associated with an impairment of the vestibular-ocular reflex (VOR), which can be assessed by various methods, according to Dr. Leif Erik Walther of the University of Heidelberg, Dr. Jan Lohler of University Hospital of Schleswig-Holstein in Lübeck and colleagues.

Although the bithermal vestibular caloric test is considered the reference standard, the test is invasive, time-consuming and unpleasant for patients. By contrast, HIT methods, including video HIT, are noninvasive and can be performed quickly in emergency departments and at the bedside. However, their diagnostic accuracy is questionable.

"In vertigo syndromes, a correct diagnosis has a decisive influence on the recommendation and initiation of adequate therapy and, finally, its success," Drs. Walther and Lohler told Reuters Health by email.

"If, for example, treatment of Meniere's disease is sought, the likelihood of the disease being present must be as high as possible," especially when ablative therapy methods or surgical interventions are being considered, they said. Therefore, Drs. Walther, Lohler and colleagues performed a scoping review to compare the diagnostic accuracy of various HIT methods with other vestibular tests and clinical diagnosis.

As reported online April 25 in JAMA Otolaryngology Head and Neck Surgery, the team searched the literature from inception to April 2017 and identified a total of 27 diagnostic studies that included 3,821 participants.

Disagreements emerged both within and between studies when the various HIT methods were compared with other diagnostic tests. Sensitivity ranged between 0% and 100%, with a median of 41%. By contrast, specificity in identifying people without a vestibular disorder was higher, ranging from 56% to 100% (median, 94%).

For example, 10 studies compared video HIT versus the caloric test. Four focused on patients with a history of vestibular neuritis and the remaining six provided diagnostic test accuracy data to distinguish between vestibular and nonvestibular disorders. For the latter, sensitivity ranged from 22% to 79%, and specificity, from 66% to 100%.

To detect chronic vestibular neuritis, three studies reexamined patients with a history of the disorder one month to a year after the first diagnosis. Sensitivity ranged from 44% to 78% and specificity, from 95% and100%, respectively, to detect chronic cases.

"We found differences in test results for high-frequency (e.g., video HIT), medium-frequency (e.g., rotational tests by chair examination), and low-frequency analysis of horizontal VOR (caloric irrigation)," Drs. Walther and Lohler said. "Therefore, these methods represent independent vestibular tests. Different diseases show different test results in the dynamic range of horizontal VOR."

For example, in Meniere's disease, abnormalities are seen in the caloric test analysis, whereas normal results are seen on video HIT. "This finding should ultimately be considered in the choice of the diagnostic procedure and treatment decisions in vestibular disorders," they said.

"The results of this evidence analysis are by no means to be interpreted negatively, however," they note. "Video HIT is a modern method that can be used regardless of the condition of the outer and middle ear. It is non-invasive and expeditious, even if spontaneous nystagmus is present."

"The clinical version of HIT can be used as a screening method," they suggest. "For horizontal VOR, video HIT has a much higher test accuracy."

Dr. Jose Lopez-Escamez, an otolaryngologist at the Hospital Virgen de Nieves, Granada and author of a related editorial, told Reuters Health, "I was not surprised by the results of this review. HIT is a very useful test to assess vestibular function, but this will not give you the diagnosis in most cases. In fact, the majority of patients with dizziness or vertigo are diagnosed using clinical symptoms".

"I need 30 minutes for a dizzy patient," he said by email. "Honestly, I recommend that ENTs spend more time taking a detailed clinical history including age of onset, duration of symptoms, triggers of the attacks (positional changes) and accompanying symptoms (headache, hearing loss, tinnitus) with an oculomotor examination, instead of requesting exhaustive vestibular testing."

"A normal vestibular test does not rule out a clinical diagnosis, except for bilateral vestibular loss," he added. "In the emergency room, an oculomotor examination is essential and the diagnosis should be guided to discriminate benign vertigo from stroke, brainstem or cerebellar lesions."

SOURCE: http://bit.ly/2J62SK4 and http://bit.ly/2J7rBxA

JAMA Otolaryngol Head Neck Surg 2019.