Benign Paroxysmal Positional Vertigo and Otolith Repositioning

It is generally agreed that BPPV results from dysfunction of the posterior semicircular canal (PSCC). The characteristic rotary nystagmus seen in BPPV can be reproduced by electrical stimulation of the PSCC and eliminated by deafferentation of the PSCC. Two theories have been advanced to explain the pathophysiological characteristics of BPPV; these are cupulolithiasis and canalithiasis. The former is Schuknecht’s original theory of a substance adherent to the cupula, while the latter presumes the presence of free-floating debris within the posterior canal. Temporal bone studies may not be able to provide sufficient evidence to differentiate between the 2 theories. Moriarty et al showed that deposits are present on all of the semicircular canal ampullae, although the PSCC is most commonly involved. Supportive evidence for the canalithiasis theory is provided by surgeons who have noted freely moving particles within the semicircular canals during the translabyrinthine approach to the cerebellopontine angle and when performing posterior canal occlusion. Regardless of whether debris is fixed or free floating, it is surmised that if the debris could be removed from the canal, the patient would be rendered free of symptoms. Noninvasive techniques for the removal of this debris have been developed. Brandt and Daroff initially reported on the use of a positioning technique for elimination of BPPV. They noted abrupt resolution of symptoms in one third of their patients. While recognizing a propensity for spontaneous resolution of symptoms, they concluded the time course of the recovery was consistent with a mechanical removal of debris and did not represent central compensation. Renewed interest in physical therapy for BPPV followed descriptions of repositioning maneuvers by Semont et al and Epley. Semont et al adhered to the theory of cupulolithiasis. Therefore, their intervention is directed at dislodging a fixed deposit from the cupula. In performing this maneuver, a patient is asked to sit on the side of an examination table with the head turned away from the affected ear. The patient is then rapidly moved to a lateral decubitus position, with the head facing the ceiling. After a few minutes, the patient is quickly sat up and then moved to the opposite lateral decubitus position without changing the orientation of the head on the body. Thus the patient is now facing the floor. The patient then sits up and is asked to remain upright for 48 hours. Epley favored the canalithiasis theory. He devised a technique to move the head in a manner that rotates the posterior canal about its central axis, bringing the ampullated end from a dependent position to its zenith. This induces gravity-directed movement of particulate matter into the vestibule, where it should not produce symptoms. The patient is initially placed in the Hallpike position with the affected ear down. While remaining in the supine position, the patient’s head is rotated to the contralateral side. Next, the body is rolled onto the contralateral shoulder with no change in head position, thus effectively rotating the head 180° from the initial position. Finally, the patient is sat upright with the chin down. A handheld oscillator is applied to the skull throughout the positioning sequence to dislodge any fixed deposits in an effort to thoroughly clear the PSCC. Once again, the patient is asked to remain upright for 48 hours after the procedure. Most subsequent studies use these techniques exactly as described by the original authors or with minor variations. Reported results are quite encouraging. The Table lists data from selected studies, grouped according to the type of intervention. For accurate comparison, only those patients with no evidence of positional vertigo on follow-up are listed as cured. Some authors use a single treatment approach, while others repeat therapeutic measures at intervals from several days to weeks. A treatment session may include a single maneuver or multiple repetitions. Is one technique better as a single treatment? In a prospective randomized From the Department of Otolaryngology, University of Texas Medical Branch, Galveston. CLINICAL CHALLENGES IN OTOLARYNGOLOGY