Most common peripheral vestibular disorders

Most common peripheral vestibular disorders

What is the most common major peripheral vestibular disorder and what are the characteristics? 

The most common cause of episodic vertigo and peripheral vestibular disorder is benign paroxysmal positional vertigo (BPPV).

It is probably caused when particles of otoconia become fractured or displaced from the otoconial membrane, enter the common crus, and, in over 95% of cases, fall into the posterior canal, attaching themselves to the membranous wall of the canal and/or the cupula of ampulla.

Based on studies of in vitro frog labyrinths but not live humans, these two subtypes are (1) canalithiasis and (2) cupulolithiasis, respectively. In rare cases BPPV may affect the anterior semicircular canal or the horizontal canal.

The symptoms of BPPV of the posterior canal are vertigo elicited by pitch (up or down) rotations of the head and then a stationary position for several seconds, for example, looking upward toward the ceiling or a high shelf, looking downward toward the floor or under a bed, lying down in bed and rolling onto the affected side, or sitting up and transferring out of bed.

The vertigo elicited in these situations is characterized by a delay to onset of a few seconds from moving the head into the stimulus position to the onset of vertigo. It is often intense but lasts only a few seconds. 

The standard clinical test for posterior canal BPPV is the Dix–Hallpike maneuver. In this test the patient sits with her legs in front of her.

The clinician turns the patient’s head 45° to the side to be tested, if possible, and then pitches the head back as the patient lies supine, so that at the end of the motion the neck is hyperextended approximately 30° if possible.

For a patient with cervical limitations or other musculoskeletal limitations the test can be adapted by having the patient lie partly supine on the ipsilateral scapula or even lie on the ipsilateral side but facing contralaterally away from the test side, in the side lying test. 

Nystagmus elicited by the Dix–Hallpike maneuver is pathognomonic if the nystagmus has the following characteristics: beating (quick phases) upward in the vertical plane, ipsilateral to the test side in the horizontal plane, and torsion of the eye also beating ipsilateral to the test side.

So, the quick phases act like an arrow pointing to the affected side. The nystagmus appears 2 to 30 seconds after the head has been moved into the test position. It waxes and wanes, with a few small beats, larger beats, and then smaller beats again.

During Dix–Hallpike testing patients will complain of vertigo with the delay to onset and the same duration as the nystagmus.

They may become diaphoretic or anxious and may have nausea during the test and afterward.

After seconds to minutes the nausea subsides. 

Nystagmus is inhibited with visual fixation, so the best way to perform the Dix–Hallpike maneuver is with fixation-occluding magnifying lenses over the eyes. Traditional evaluation included high plus or magnifying lenses (Frenzel lenses) that magnify the eyes and prevent the patient from focusing on a pattern.

Frenzel lenses have been largely replaced with infrared video-oculography, in which small infrared video cameras imbedded in goggles are placed over the patient’s eyes.

The image is then either recorded on a laptop computer or viewed on a screen. The alternative, older recording technique is electronystagmography (ENG), also known as electro-oculography , in which electrodes placed around the eyes record the corneoretinal potential. 

BPPV of the anterior canal and horizontal canal is possible, but unusual.

To test the patient for anterior canal BPPV, use the reverse side lying test: while the patient sits on the side of the treatment table, turn her head 45° to face the test side.

Rapidly place the patient nose downward and have her lie on the ipsilateral shoulder.

Wait for the onset and cessation of nystagmus. To test the patient for lateral canal BPPV have the patient lie supine with the neck pitched forward (downward) approximately 30° to bring the horizontal canal into alignment with earth vertical. Rotate the head to either side, waiting several seconds to observe nystagmus. 

Approximately half of BPPV patients complain of disequilibrium and have balance impairments. They may fail Romberg testing.

Therefore these patients complain of difficulty walking, particular difficulty ascending and descending stairs, and particular difficulty walking on unstable surfaces. 

The recurrence rate for BPPV is high; at least 30% of patients have a recurrence. The disorder is twice as common on the right as on the left and twice as common in women as in men.

The first onset often occurs in the late 40s or early 50s and becomes more common with advancing age.

Comorbidities include mild head trauma for which the patient may not have sought medical attention or more severe head trauma, smoking, diabetes, upper airway inflammatory disease such as cold, flu, allergies or sinus infection, and any other vestibular impairment.

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