11 Benign paroxysmal positional vertigo (BPPV) is a very common condition, accounting for 171 to 23%2 of all causes of dizziness referred to a neurotology clinic. The condition typically occurs in the middle to late decades, and there is a female:male preponderance of ~2:1. BPPV is most often idiopathic but may be secondary to head trauma, labyrinthitis, stapes surgery, or chronic ear disease. Adler initially described BPPV3 in 1897, although Barany is credited with the first description of this disorder in 1921.4 BPPV is characterized by recurring attacks of vertigo, acute in onset, of short duration, and provoked by a specific head movement. Lying down or arising, sudden head rotation, or extending the neck may provoke symptoms of vertigo. This condition is often self-limited and is typically characterized by spontaneous remissions after days to even months, with recurrences possible as late as 10 to 20 years after remission. ■ Pathophysilogy Experimental,5, 6 pathological,7–9 and clinical evidence10–12 indicates that BPPV is due to a deranged response of one of the semicircular canals. BPPV may involve any one or a combination of semicircular canals. The posterior semicircular canal (PSCC) is the most commonly involved, accounting for ~90% of cases of BPPV.13 The remaining 10% of cases are equally divided between the lateral and superior semicircular canals. It is believed that the deranged response of the semicircular canals in patients with BPPV is due to degenerated debris or dislodged otoconia and their effect on the canals.9,14,15 The otoconia may be dislodged because of head trauma, degeneration due to aging, vascular insult, previous otologic conditions such as Meniere’s disease, chronic otitis media, serous or neuro-labyrinthitis, or previous otologic surgery such as stapedectomy. In most series, idiopathic causes account for the majority of patients (~80%) with BPPV. Unilateral ear involvement is most characteristic, but bilateral BPPVmay occur in up to 15 % of patients.16 Two different theories, cupulolithiasis and canalithiasis, have been proposed to explain the characteristics of benign paroxysmal positional nystagmus. Cupulolithiasis9 (coined by Schuknecht) proposes that degenerative otoconial debris from the utricle adheres to the surface of the cupula of the semicircular canal, making it gravity sensitive. The increased density of the cupula relative to the endolymph results in an inappropriate deflection of the cupula of the canal when the head is moved to a position in which the semicircular canal is in a plane parallel to the pull of gravity. The second theory, canalithiasis,14 suggests that the degenerative debris is free floating in the endolymph of the long arm of the semicircular canal. The clot of free-floating otoconial debris acts as a plunger on the endolymph and cupula of the canal. In the upright position, debris rests at the base of the cupula without any noticeable effect. If the head is turned and rapidly positioned to the side in the plane of the involved semicircular canal, the clot, because of its greater specific weight, gravitates downward. By endolymph flow, the clot deflects the cupula in an ampullofugal direction leading to the observed nystagmus. When the clot has gravitated to the lowest curvature of the involved canal, vertigo and nystagmus subside because the cupula assumes its normal resting position. Currently, cana-lithiasis is considered the most common mechanism in the majority of, if not all, cases of BPPV. ■ Diagnosis The diagnosis of BPPV is made by the history of vertigo induced by certain head movements as well as findings of the characteristic nystagmus with the patient’s head in a provocative position (Dix-Hallpike test). In 1952, Dix and Hallpike3 described the following unique and characteristic set of symptoms and signs of BPPV, which still hold true today: 1. Critical provocative position. The vertigo attack is typically provoked when the patient’s head is placed supine with the involved ear undermost. 2. Characteristic nystagmus. Concurrent with the vertiginous symptoms, there is a geotropic rotatory upbeat nystagmus (posterior semicircular canal variant), ageotropic rotatory downbeat nystagmus (superior semicircular canal variant), or horizontal direction-changing nystagmus (horizontal semicircular canal variant). 3. Latency. There is generally a brief period of 1 to 5 seconds of latency from the time the head position is assumed until the attack begins. 4. Limited duration. The attack is transient and ceases within 5 to 30 seconds but may last up to 1 minute. 5. Fatigability. Upon returning the patient to the provocative position one or more times within a short period, there is a rapid fatigability of nystagmus and vertigo, and the attacks often cannot be reelicited during the same examination. 6. Reversal. Upon returning the subject to the erect position, there may be a rotatory nystagmus in the opposite direction to the nystagmus seen in the head-hanging position. A positive response to the Dix-Hallpike test is virtually diagnostic of BPPV, provided all features are present. Not all features listed here are required to make the diagnosis, however. Some cases do not exhibit a latency period. One possible theory for a lack of a latency may be that these cases are the result of cupulolithiasis, as opposed to canalithiasis. The cupulolithiasis theory proposes a heavy cupula, which would result in rapid cupular movement during provocative positioning. Horizontal canal BPPV has a unique set of features.17 Vertigo attacks occur when the head is turned quickly from the supine to either lateral position. There is a very short or absent latency; nystagmus is present with the head turned to either side, but the nystagmus is most intense and has the longest duration when the head is turned to the affected ear; the nystagmus typically does not fatigue with repeat positioning. BPPV may involve more than one semicircular canal in the same patient. Furthermore, BPPV may convert from the posterior canal to either a horizontal or superior canal variant after canalith repositioning.18 ■ Treatment Before effective treatment can be offered, the correctness of the diagnosis is necessary. Furthermore, the potential complications associated with treatment must be considered whether the treatment is invasive or not. Table 11–1 discusses potential pitfalls and solutions. ■ Nonsurgical Treatment There have been several treatments proposed for BPPV, including vestibular suppressants,19 vestibular habitua-tion training,20 at-home therapy (Brandt-Daroff exer-cises21), in-office procedures (the Semont “Et Maneuver Liberatoire”22 and the canalith repositioning procedure of Epley14), and surgery.11,23 Both the at-home and in-office treatments attempt to advance the otoconial debris or clot from the semicircular canal into the vestibule to relieve symptoms. One of the most common and effective treatments is the canalith repositioning procedure (CRP).14 The CRP is based on the canalithiasis theory of BPPV. During the CRP, the supine patient’s head is manipulated so that the posterior semicircular canal is coplanar with gravity. In this way, there is migration of the canaliths out of the posterior semicircular canal and into the utricle through the common crus. The direction of movement of the canaliths determines the direction of induced or secondary nystagmus during the procedure. Secondary nystagmus that is of the same direction as the nystagmus in the initial Dix-Hallpike position indicates appropriate movement of the canaliths away from the ampulla and toward the common crus and utricle.24 A modification of the CRP as originally described by Epley may be used to treat the horizontal variant of BPPV. For the horizontal canal variant, a 270 degree head rotation is performed around the supine patient’s longitudinal axis.25 The rotation is started toward the unaffected ear in steps of 90 degree increments. Problem Prevention/Treatment Correct diagnosis of benign paroxysmal positional vertigo (BPPV) Suggestive history Geotropic rotary nystagmus on Dix-Hallpike testing Ageotropic rotary or horizontal nystagmus on Dix-Hallpike testing less common Nystagmus onset after a latency of 1 to 5 seconds Resolution of nystagmus within 1 minute Fatigability of nystagmus Lack of response of BPPV to canal repositioning procedures Habituation exercises Brandt-Daroff exercises Lack of response of BPPV to vestibular rehabilitative exercises Consider surgery Surgical treatment of incorrect semicircular canal (i.e., posterior instead of horizontal) Prevent with careful evaluation of the nystagmus on the provocative maneuver Inappropriate surgery for vertigo related to a posterior fossa lesion Prevent with magnetic resonance imaging encompassing the cerebellopontine angle prior to surgical intervention Inappropriate surgery for vertigo related to a central cause Careful assessment of appropriate history and a positive Dix-Hallpike examination with appropriate nystagmus accompanied by subjective vertigo Posterior semicircular canal occlusion Hearing loss Careful blue-lining of the posterior semicircular canal maintaining an eggshell bony covering Removal of posterior semicircular canal perilymph using a cottonoid or gelatin foam Perilymph fistula Posterior semicircular canal fenestration closure using temporalis fascia Singular neurectomy Hearing loss Avoidance of violation of round window membrane Maintenance of a bony ridge between the trough for the singular canal and round window attachment Postoperative dysequilibrium Commencement of vestibular rehabilitation immediately following surgery The success of the CRP for PSCC BPPV has been well documented, with vertigo cure rates ranging from 57 to 94%.13,14,24,26 Patients with BPPV confined to a single PSCC have the best prognosis for success with the CRP. Patients who have BPPV that involves more than a single PSCC (e.g., horizontal or superior canal variants, BPPV in multiple ipsilateral canals, bilateral BPPV) are more likely to require multiple CRP treatments.27 A small group of patients, regardless of the number of involved canals, does not respond to the CRP, or any form of conservative therapy. ■ Comorbidity Some patients with BPPV may have additional vestibular pathology. If so, patients are more likely to have persistent dizziness symptoms even after successful nonsurgical28 or surgical treatment of the BPPV. Additional vestibular pathology may be identified through history (e.g., history of nonvertiginous dizziness, dys-equilibrium, spontaneous rather than positional vertigo, other neurological symptoms, etc.) or vestibular testing (e.g., electronystagmography, rotary chair testing). There is also a certain amount of utricular dysfunction in the majority of patients with chronic BPPV.29 Persistent utricular dysfunction may be one of the causes of dysequilibrium experienced by some patients after successful canalith repositioning procedures.30
Surgery for Benign Paroxysmal Positional Vertigo
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