In my relatively new position running a Balance Disorders program at a large teaching hospital, I am exposed to a very different patient population than what I encountered in my private practice. One example of this is being exposed to patients that have recently undergone cochlear implantation.

 One recent case triggered my curiosity about how often a patient might experience a vestibular injury, or some temporary vestibular symptoms, following implant surgery. This nice lady was doing well with her implant. She was in her sixties and hearing for the first time in years. About two weeks after the surgery, she woke to vertigo, nausea and disequilibrium.  The surgeon asked me to see her that same day.

On arrival, she had spontaneous nystagmus following Alexander’s law, beating away from the implant side.  This pattern would be interpreted as a likely recent reduction in function of the labyrinth in the implant ear. This pattern is most often the result of a viral inflammation of a branch of the vestibular nerve that connects the inner ear to the brain (a condition known a vestibular neuritis) . The patient had no prior viral symptoms, and it would have been awfully coincidental to occur two weeks after surgery. Her rotary chair on that day also suggested a recent reduction in labyrinthine function on the implant side. A recheck one week later showed improvements in all of the above, including her symptoms.

I decided to review the literature regarding vestibular symptoms or measurable dysfunction after cochlear implantation. Here is summary of what I found:

Several studies measured caloric responses on the implant side, both pre and post surgery. Reports indicate that there is a measurable reduction in caloric response in about 30% when averaging these several studies. One study also looked at changes in rotational chair results and saw reduction in VOR response in about 30%.  In a small study, cVEMP responses were reduced in 40%.

 Subjectively, these changes don’t always translate into significant or prolonged symptoms. Some studies showed a significant increase in complaints of dizziness shortly after surgery, while one large study showed no change at 4 months post-surgery.

 It seems that patients undergoing cochlear implant surgery might benefit from counseling that changes in vestibular function are not unusual, may cause some temporary symptoms, but are unlikely to have lasting effect.

Photo courtesy of National Institute of Health


A summary of “An Abbreviated Diagnostic Maneuver for Posterior Benign Paroxysmal Positional Vertigo”, Michael, P.,  et al (2016).

 

 

The authors of this article report that canalothiasis (free floating otoconia) of the posterior canal is the most common single cause of vertigo.  Treatments are easy, inexpensive, safe and effective, yet people wait months to years without proper diagnosis and treatment. The authors theorize that this may be due to the difficulty (perceived or real) of performing the Dix-Hallpike maneuver, which requires and examination table and the patient being placed in the supine head hanging position at least twice.

They offer an alternative to the Dix-Hallpike maneuver that does not require an examination table. In this abbreviated modification of the Dix-Hallpike, the patient in seated in a sturdy chair with a back. The patient sits on the front edge of the chair, turns their head to the side being examined, and leans back extending their head over the back of the chair. No video goggles or Frenzel lenses are used in the study, as the authors wanted to measure the utility of this maneuver in a typical primary care practice setting.  (Editors note: Nystagmus associated with posterior canal BPPV is visible to the naked eye).

Patient with suspected BPPV first underwent the abbreviated version, then came back on another day to undergo the traditional Dix-Hallpike maneuver. This removed the impact of a fatigued response related to repeated stimulation on the same day.

In this study, a positive response on the abbreviated maneuver was compared to a positive response on a traditional Dix-Hallpike with the benefit of video goggles. In the abbreviated maneuver, a positive response included nystagmus and/or unilateral symptoms triggered by the maneuver. For the traditional Dix-Hallpike, only a nystagmus response was considered positive.

Findings: 

When using the criteria of nystagmus or unilateral symptoms on the abbreviated maneuver, it was 80% predictive of a positive traditional Dix-Hallpike. When only considering the presence of nystagmus on the abbreviated maneuver, it was 50% predictive.  Of those with unilateral symptoms, but no visible nystagmus on the abbreviated maneuver, 30 of 31 patients had a positive Dix-Hallpike on follow up. Of those patients in the study with a history suspicious for BPPV, but no nystagmus or unilateral symptoms on the abbreviated maneuver, none had a positive Dix-Hallpike.

The authors state that the abbreviated maneuver “showed fair sensitivity (80%) and high specificity (96%)” when considering either triggered nystagmus and/or unilateral positional subjective dizziness or vertigo to be the diagnostic criteria for suspected (posterior canal) pc-BPPV.

Opinion:

These results are both logical and impressive. This technique needs to be studied and independently verified, but I think it holds great promise as part of a movement to improve the diagnostic efficiency in the Emergency Department and Primary Care setting.