Vertigo can have many possible causes
Finally, the “test of skew” is performed by again having the patient fixate on the examiner’s nose. Each eye is tested by being covered, and then uncovered. If the uncovered eye has to move to refocus on the examiner’s nose, then the test is positive for a central lesion. A positive head impulse, positive horizontal nystagmus, and negative test of skew is 100% sensitive and 96% specific for a peripheral lesion.11
Benign paroxysmal positional vertigo (BPPV) is vertigo that is triggered by movement of the head. It occurs when otoconia that are normally embedded in gel in the utricle become dislodged and migrate into the 3 fluid-filled semicircular canals, where they interfere with the normal fluid movement these canals use to sense head motion, causing the inner ear to send false signals to the brain.12
Diagnosis is confirmed by performing the Dix-Hallpike maneuver to elicit nystagmus. The patient is moved from a seated to a supine position with her head turned 45 degrees to the right and held for 30 seconds. For a demonstration of the Dix-Hallpike maneuver, see https://youtu.be/8RYB2QlO1N4. The Dix-Hallpike maneuver is also the first step of a treatment for BBPV known as the Epley maneuver. (See “The Epley maneuver: A procedure for treating BPPV”.13,14)
The Epley maneuver: A procedure for treating BPPV
Benign paroxysmal positional vertigo (BPPV) can be treated with the Epley maneuver. Like the Dix-Hallpike maneuver, the Epley maneuver isolates the posterior semicircular canal of the affected ear. However, it goes a step further to reposition otolithic debris away from the ampulla of the posterior canal, rolling it through the canal and depositing it in the utricle, where it will not stimulate nerve endings and produce symptoms.
For a demonstration of the Epley maneuver, see https://youtu.be/jBzID5nVQjk. A computer-controlled form of the Epley maneuver has been developed and can be as effective as the manual version of this procedure.13
In 38% of patients, BPPV spontaneously resolves. The Epley maneuver can improve this rate to 64% with a single treatment, and one additional maneuver improves the success rate to 83.3%.14 If this procedure doesn’t work the first time, there may be more sediment that didn’t have enough time to settle during the procedure. Therefore, the Epley maneuver can be repeated 3 times a day, and performed on subsequent days as needed.
Labyrinthitis—inflammation of the inner ear that can cause vertigo—is suggested by an acute, non-recurrent episode of dizziness that is often preceded by an upper respiratory infection. If the external canal is extremely painful and/or develops a vesicular rash, the patient might have herpes zoster of the geniculate ganglion (Ramsay Hunt syndrome type 2).
Vertigo can have many possible causes
Vestibular migraine and Meniere’s disease. When a patient who has a history of migraines experiences symptoms of vertigo, vestibular migraine should be suspected, and treatment should focus on migraine therapy rather than vestibular therapy.15
Symptoms of Meniere’s disease and vestibular migraine can overlap.16 The current definition of Meniere’s disease requires ≥2 definitive episodes of vertigo with hearing loss plus tinnitus and/or aural symptoms.17 Thirty percent of vertigo episodes in patients with Meniere's disease can be attributed to BPPV.18
Acoustic neuroma. In addition to vertigo, acoustic neuroma is often associated with gradual hearing loss, tinnitus, and facial numbness (from compression of cranial nerve V preoperatively) or facial weakness (from compression of cranial nerve VII postoperatively). Unilateral hearing loss should prompt evaluation with magnetic resonance imaging.
“Acoustic neuroma” is a misnomer. The lesion arises from the vestibular (not the acoustic) portion of the 8th cranial nerve, and isn’t a neuroma; it is a schwannoma.19 Although it actually arises peripherally within the vestibular canal, it typically expands centrally and compresses other nerves centrally, which can make the clinical diagnosis more challenging if one were using the classical schema of differentiating between peripheral and central causes of vertigo.
Age-related vestibular loss occurs when the aging process causes deterioration of most of the components of the vestibulo-ocular reflex, resulting in dizziness and vertigo. Usually, the cerebral override mechanisms can compensate for the degeneration.
Other causes of vertigo include cerebellar infarction (3% of patients with vertigo),20 sound-induced vertigo (Tullio phenomenon),21 obstructive sleep apnea,22 and systemic sclerosis.23 Diabetes can cause a reduction in vestibular sensitivity that is evidenced by an increased reliance on visual stimuli to resolve vestibulo-visual conflict.24