We are back with a few more “Action Statements” to continue with my “faux” Clinical Practice Guideline (CPG) for Acute Vertigo.
Patients complaining of vertigo-dizziness should undergo screening for acute and positional nystagmus before more expensive, lower yield tests are ordered.
A 2009 study out of the Veterans Administration retrospectively reviewed the medical records of 193 adult patients over a five year period diagnosed with the simplest and most treatable form of vertigo-dizziness, Posterior Canal BPPV. After correct diagnosis and treatment, all patients in the study improved.
Prior to correct diagnosis and treatment, 71% had additional testing, none of which diagnosed them with BPPV. Thirty eight percent had cranial MRI, 16% had a cranial CT Scan, 32% had an audiogram, 21% had blood work, 12% had videonystagmography (which is the only test listed that could potentially reveal BPPV).
In 2013, a much larger and more disconcerting study was completed. Out of 3522 patients seen in the Emergency Department for the complaint of dizziness, a test for positional vertigo was performed on only 137 patients (less than 4 %). Treatment for BPPV was completed for only 8 patients (0.2%). Almost 80% of patients diagnosed with BPPV did not undergo any testing that could confirm the disorder, and less than 4% diagnosed with BPPV received treatment known to be most safe and effective for BPPV.
Patients with acute vertigo should be observed for nystagmus with the benefit of infra red video goggles.
While it is true that nystagmus associated with BPPV is visible without the benefit of video goggles or Frensel’s lenses, the same is not true for nystagmus associated with acute vertigo. It is also not true that both (video goggles and Frensel’s lenses) are equally effective at removing visual fixation that suppresses potentially visible nystagmus that would allow clear diagnosis in many cases. The most clear representation of this is a 2004 study of 100 patients with acute vertigo. All (100%) of the patients had diagnostically useful visible nystagmus when viewed under infra red video goggles. In the same group of patients, on the same day, nystagmus were visible in only 33 patients (33%) under Frensel’s lenses.
A second study assessing the sensitivity and specificity of observing for nystagmus though video goggles, frensel’s lenses or direct observation has more variables (multiple tests) but makes a similar point. Patients underwent evaluation for spontaneous, positional and headshake nystagmus, and examiners were able to detect labyrinthine deficient patients with 77% accuracy when using video goggles compared to the other two observation techniques at around 50%. While sensitivity was equal among the three techniques, specificity when using video googles was more than double that of Frensel’s lenses or direct observation.
Specificity and sensitivity of different techniques for observation of nystagmus of labyrinthine origin.
| Direct observation | Frenzel’s glasses | Videonystagmoscopy | |
| Specificity | 35.6 | 43.7 | 91.6 |
| Sensitivity | 88.7 | 88.7 | 84.2 |
We will wrap this up next week with some suggestions for examination techniques that are most sensitive and cost effective when examining a patient with acute vertigo.
Photo courtesy of Micromedical.com
