Some thoughts on peripheral vestibular disorders

Effectiveness of Treatments for Benign Paroxysmal Positional Vertigo of the Posterior Canal

OBJECTIVE

To determine which common, nonpharmacological, nonsurgical treatments are most effective for treatment of benign paroxysmal positional vertigo (BPPV).

STUDY DESIGN

Prospective, randomized, sham-controlled.

PATIENTS

Patients (n = 124) with BPPV of the posterior semicircular canal.

SETTING

Tertiary care center.

INTERVENTIONS

Random assignment to one of five groups: modified canalith repositioning maneuver (CRP), modified liberatory maneuver (LM), sham maneuver, Brandt and Daroff's exercise, and vertigo habituation exercises. Subjects received a standard educational lecture about BPPV and the purpose of the intervention. No vestibular-suppressant medication or special instructions for head positioning were used. Post-tests were given at 1 week after treatment and at approximately 3 months and 6 months later.

MAIN OUTCOME MEASURES

Vertigo intensity and frequency.

RESULTS

Multilevel analyses showed that vertigo decreased significantly after LM, CRP, and Brandt-Daroff exercise; those three groups did not differ significantly. The habituation group did not differ from sham, Brandt-Daroff, LM, or CRP groups. Changes in scores were maintained throughout the 6-month follow-up period.

CONCLUSION

LM, CRP, and exercises are all effective interventions; patient education plus the sham maneuver, however, had some beneficial effect. These results support two possible mechanisms of BPPV: displaced otoconia and a neural mechanism affecting interpretation of semicircular canal signals.

Recovery from vestibular ototoxicity

OBJECTIVE

Determine whether subjects with documented vestibular ototoxicity recover vestibular function and, if so, investigate the recovery dynamics.

STUDY DESIGN

Prospective and retrospective reviews and repeated measures.

SETTING

Clinical research and technology center.

SUBJECTS

Twenty-eight subjects who received vestibulotoxic medications were followed for at least 12 months after initial treatment.

CONTROLS

Our subject sample was compared with a published database of normal individuals.

INTERVENTIONS

All 28 subjects received systemically administered medications known to be ototoxic. The subjects' treating physicians controlled medication, dosage, and administration schedules.

MAIN OUTCOME MEASURES

Tests of horizontal canal vestibulo-ocular function were performed. Subjects' auditory and vestibular symptoms were recorded.

RESULTS

Eleven subjects (39%) showed changes in horizontal canal vestibulo-ocular gain constant (GC) and/or time constant (TC) consistent with vestibular ototoxicity. When tested 1 year after ototoxic drug administration, eight of the nine subjects who experienced ototoxic decrease in GC showed a recovery of GC to normal limits. Only one of the eight subjects who experienced ototoxic decrease in TC showed recovery of TC to within normal limits. Ototoxicity onset and recovery were independent of baseline vestibular function, and ototoxicity onset did not correlate with cumulative dose of ototoxic medication. There was no relationship between subjective symptoms and ototoxicity onset.

CONCLUSIONS

Recovery of GC after vestibular ototoxicity is more commonly observed than recovery of TC. Because ototoxic changes developed and continued in an unpredictable time and manner in relation to ototoxic drug administration, we propose that once ototoxic changes in vestibulo-ocular reflex are detected, ototoxic medications should be discontinued as soon as possible.