Burak Ömür Çakır, MD, I˙brahim Ercan, MD, Zeynep Alkan Çakır, MD, S¸ enol Civelek, MD, I˙brahim Sayın, MD, and Suat Turgut, MD, Istanbul, Turkey
OBJECTIVE: To assess the correct incidence of horizontal semicircular canal (H-SCC) benign paroxysmal positional vertigo (BPPV).
STUDY DESIGN: Retrospective assessment of patients with BPPV.
METHODS: All patients with BPPV were included and the rates of involvement of posterior, horizontal, and anterior SCCs were determined.
RESULTS: One hundred sixty-nine patients with the diagnosis of BPPV were evaluated. One hundred forty-four patients (85.2%) were found to have posterior SCC (P-SCC) involvement, and there were 20 patients (11.8%) with horizontal SCC (H-SCC) and 2 patients (1.2%) with anterior SCC (A-SCC) involvement. Three patients (1.8%) had simultaneous H-SCC and P-SCC BPPV ipsi- laterally. Geotropic nystagmus was seen in 17 out of 23 patients (73.9%) in roll test, and ageotropic nystagmus was seen in the remaining 6 patients (26.1%).
CONCLUSION: H-SCC constitutes 13.6% of all BPPV cases. H-SCC BPPV with geotropic nystagmus is more com- mon. H-SCC BPPV can coexist with ipsilateral P-SCC BPPV. However, in some cases of H-SCC BPPV, Dix-Hallpike ma- neuver can cause vertigo and horizontal nystagmus. This may be confused with P-SCC BPPV. Therefore, the roll test must be performed in all cases in addition to Dix-Hallpike maneuver and both ears must be evaluated with respect to all SCCs for BPPV.
Benign paroxysmal positional vertigo (BPPV) is a com- mon vestibular disorder and occurs due to head motion resulting in temporary vertigo. It was first described by Barany in 1921. There are two main hypotheses to explain the development of BPPV. Schuknecht1 supports the cupu- lolithiasis theory, which is based on the attachment of oto- lithic debris to the cupula in crista ampullaris. Hall et al2 propose the theory of canalithiasis, which is based on free- floating debris in the canal. Both these theories support the presence of foreign particles in SCC as a cause of vertigo. It has also been speculated that those particles are otoliths of calcium carbonate nature originating from the macula of the urticle.
Mostly, posterior semicircular canal (P-SCC) is affected. Dix and Hallpike report that the maneuver be performed at the end of a latency period (5-30 seconds) to demonstrate the presence of a temporary vertigo. The presence of verti- cal upbeating and rotatory-type nystagmus toward the lower ear and the nystagmus developing in the opposite direction along with the occurrence of vertigo when brought back to sitting position confirm the diagnosis. Exhaustion of vertigo and nystagmus is typical with the resumption of the maneu- ver.
A horizontal (H-SCC) variant of BPPV was first pro- posed by McClure in 1985. He reported on patients with positional vertigo and horizontal direction-changing posi- tional nystagmus.6 The symptoms can be produced by roll- ing the head while the patient lies in a supine position. In canalithiasis, horizontal nystagmus appears after a short latency period. When the head is turned 90 degrees to the left or to the right at the supine position, the fast component is directed downward (geotropic). When the patient’s head is rolled to the contralateral side, direction of the nystagmus is changed. In cupulolithiasis or canalithiasis with short canal, the fast component of nystagmus is directed upward (ageotropic). The nystagmus and vertigo with H-SCC BPPV manifest a shorter latency and a longer duration.
The treatment consists of canalith repositioning maneu- vers appropriate for the SCC involved. Therefore, it is crucial to determine which part of SCC is involved. P- and H-SCC BPPV are two different conditions as they imply two different diagnoses and treatment methods. The inci- dence of H-SCC was reported between 1.9% and 22%.7-16 In our study, all of the patients presenting to the clinics with vertigo symptoms had Dix-Hallpike and roll tests to assess BPPV for all three SCCs and the incidence of H-SCC BPPV was reviewed in light of the literature
Table 1: BPPV distribution of various studies according to the involvement of semicircular canals
The present study was conducted at the 1st Department of Otorhinolaryngology–Head and Neck Surgery at Sisli Etfal Education and Research Hospital, Istanbul, Turkey. The study protocol was approved by the ethical board of the hospital. From November 2001 to December 2004, we as- sessed the patients with vertigo. All patients underwent Dix-Hallpike and roll tests following ear-nose-throat and neurotologic evaluations. Patients underwent pure-tone au- diometry and caloric tests and magnetic resonance imaging as indicated. Eye movements were visualized with Frenzel’s glasses, and electronystagmography was used to determine the presence of a horizontal nystagmus. In Dix-Hallpike maneuver, the presence of vertical upbeating and rotatory nystagmus toward the lower ear and the nystagmus devel- oping in the opposite direction and vertigo when brought back to sitting position confirms the diagnosis as a P-SCC BPPV. In A-SCC BPPV, the direction of the fast phase of the nystagmus is downbeating and torsional, when the pa- tient is moved into the Dix-Hallpike position. Roll test was performed in supine position, with the head fixed at 30 degrees of flexion and rotated to the right or left. Patients with geotropic or ageotropic horizontal nystagmus were diagnosed with H-SCC BPPV. Patients with positive Dix- Hallpike and roll tests on the same side were diagnosed with posterior + horizontal SSC BPPV diagnosis.
BPPV was diagnosed in 169 patients presenting to our clinic with the symptoms of vertigo. P-SCC BPPV was the con- firmed diagnosis in 144 (85.2%) patients, P- and H- SCC BPPV in 3 (1.8%), H-SCC BPPV in 20 (11.8%), and A-SCC BPPV in 2 (1.2%). Among 23 patients who were followed up with H-SCC BPPV diagnosis, geotropic nys- tagmus was seen in 17 patients (73.9%) in roll test, and ageotropic nystagmus was seen in the remaining 6 (26.1%). In 9 (39%) out of 23 patients who were diagnosed with H-SCC BPPV, horizontal nystagmus and typical vertigo developed during Dix-Hallpike maneuver. There were 12 males and 11 females, with age ranging between 26 and 81 and mean age 53.3. Vertigo and nystagmus time were found between 10 and 120 seconds in H-SCC BPPV.
The P-SCC is the most common canal of BPPV since the posterior canal is in the most gravity-dependent position. Horizontal and anterior canal variants are less prevalent because they are not in a gravity-dependent position. H- SCC BPPV has a different diagnosis and treatment com- pared to P-SCC. It was described 64 years after the posterior canal. This led to the assumption that BPPV was a disease associated with the posterior canal. This belief persisted even after the description6 of H-SCC BPPV and patients with positional vertigo were evaluated with Dix-Hallpike maneuver. This can possibly cause a group of patients with H-SCC BPPV to go unrecognized, leading to variations in the ratio of H-SCC BPPV patients to all BPPV patients. In the majority of the reports, the ratio of H-SCC BPPV was reported between 1.9% and 9.8%.7-15 However, de la Meil- leure et al16 reported this rate as 22%, which was the highest in the literature. In our study, H-BPPV incidence was de- termined as 13.6% (Table 1). There is a great variability in the rates of H-BPPV in the literature. Therefore, the ques- tion arises as to the true incidence of H-BPPV.
A-SCC BPPV is very similar to P-SCC BPPV, except that the nystagmus is in the opposite direction and down- beating. The treatment of A-SCC BPPV is the same as for P-SCC BPPV. H-SCC BPPV differs from P-SCC BPPV by having a horizontal nystagmus, shorter latency, longer du- ration, poor fatigability, higher vertigo intensity, and more emesis. Also, horizontal canal involvement is different with respect to treatment maneuver and recurrence rate.7-13
P-SCC and H-SCC can coexist in the same patient9,12,16 (Table 1). In such cases, the diagnosis and treatment of posterior canal may lead to a missed diagnosis of H-SCC BPPV, with incomplete treatment and persistence of posi- tional vertigo. Besides, during Dix-Hallpike maneuver, pa- tients with H-SCC BPPV may display vertigo and nystag- mus similar to P-SCC BPPV.17 In our study, 39% of the patients showed vertigo lasting for seconds after a short latency period and horizontal nystagmus during the Dix- Hallpike maneuver. If nystagmus is missed, these cases may be misdiagnosed as P-SCC BPPV. Therefore, in patients with nystagmus and typical vertigo of P-SCC BPPV during Dix-Hallpike maneuver, the roll test should be performed to evaluate the H-SCC.
In some studies, the patients with geotropic nystagmus only were reported. Due to this, some past reports did not reflect the entire nystagmus characteristics of H-BPPV.16,20 Depending on the localization of the particles, the fast phase of horizontal nystagmus could be geotropic or ageo- tropic7-9,11,17-19 (Table 2). The direction of nystagmus will help to determine the involved ear and the formation of a treatment protocol. In canalithiasis, rolling the head to the affected side provokes a movement of the particles toward the bottom of the canal and ampullopetal deviation of the cupula, resulting in geotropic nystagmus. Rolling the head to the healthy side provokes an opposite displacement of the particles with an ampullofugal deviation of the cupula and resulting in geotropic nystagmus. In cupulolithiasis, the maneuver to the affected side provokes an ampullofugal deviation of the cupula and the ampullopetal movement of particles occurs when rolling the head to the pathological side with ageotropic nystagmus.7 Thus, evaluation of the nystagmus helps to determine the location of H-SCC BPPV and also the accurate therapy of it.
H-SCC constitutes 13.6% of all BPPV cases. H-SCC with geotropic nystagmus is more common. H-SCC BPPV can coexist with ipsilateral P-SCC BPPV. In some cases of H-SCC BPPV, Dix-Hallpike maneuver can cause vertigo and nystagmus, and this may be mistaken for P-SCC BPPV. Therefore, roll test must be performed in all cases in addi- tion to Dix-Hallpike maneuver and both ears must be eval- uated with respect to all SCCs for BPPV.
The authors thank Zeynep Gümüs¸çü, and Özlem Gedik, Audi- ologist in SONOMED Hearing and Balance Center.