1. The Laryngoscope
Lippincott Williams & Wilkins, Inc.
© 2005 The American Laryngological,
Rhinological and Otological Society, Inc.
A Single Therapy for All Subtypes of
Horizontal Canal Positional Vertigo
Wen-Yaw Chiou, Hui-Ling Lee, Shih-Che Tsai, Tu-Hsueh Yu, Xin-Xian Lee
Objective: To demonstrate that a single therapy is INTRODUCTION
effective for treating all subtypes of horizontal canal Benign paroxysmal positional vertigo (BPPV) is man-
benign paroxysmal positional vertigo (HC-BPPV). ifested as a transitory whirling sensation along with in-
Study Design: Prospective study. Methods: Patients tense nystagmus during change of head position in rela-
with HC-BPPV (n 89) were diagnosed when the tion to the gravity vector. It has been recognized as the
supine to the head-lateral test resulted in geotropic or
most common type of vertigo and accounts for approxi-
ageotropic bilateral horizontal nystagmus. Three sub-
types of HC-BPPV were defined by their characteris- mately 20% of vertigo patients.1 Traditionally, BPPV has
tic patterns of nystagmus as well as by their specula- been associated with a lesion originating in the posterior
tive mechanism. Canalolithiasis (Can) denotes canal (PC-BPPV) and has a good resolution rate (average
geotropic nystagmus induced by free-moving otoliths 95%) after proper canalith repositioning treatment.2– 4
in the HC. Two forms of cupulolithiasis, characterized However, the incidence of horizontal canal (HC)-BPPV,
by otoliths attached either on the utricle-sided with the lesion involving the horizontal semicircular ca-
(Cup-U) or the canal-sided (Cup-C) cupula, were iden- nal, is increasing in frequency in recent years and has
tified by whether ageotropic nystagmus resolved or poorer treatment success rates ( 75%).5–7
changed to geotropic nystagmus on follow-up tests. PC-BPPV and HC-BPPV are both caused by inner ear
Forced prolonged position (FPP), lying on the healthy imbalance caused by otoliths dislocated from the utricle
side for 12 hours to easily move free otoliths to the
macula. According to the canalolithiasis (Can) theory,
utricle, has proven successful in treating Can. Al-
though Cup-U and contralateral Cup-C were associ- free-floating otoliths within the semicircular canal disturb
ated with the same positional nystagmus pattern, endolymph flow during head movement. This theory ex-
FPP with lying on the side of the weaker nystagmus plains characteristic PC-BPPV symptoms and nystag-
was found to be effective treatment, as well as consis- mus.1 Accordingly, the canalith repositioning procedure,
tent with the speculated underlying mechanism. Re- which aims to displace otoliths from the semicircular ca-
sults: All HC-BPPV patients including 49 with Can, 11 nal to the utricle, has had great success as treatment.2
with Cup-C and 29 with Cup-U had complete resolu- Moreover, the cupulolithiasis (Cup) theory, which has re-
tion of symptoms and positional nystagmus after less cently been used to elucidate the mechanism of some
than four treatment sessions. Conclusions: FPP with subtypes of HC-BPPV, hypothesizes that otoliths attach to
lying on the side of the weaker nystagmus, combined
the cupula and cause it to become a gravity-sensitive
with careful observation of nystagmus evolvement,
was found to be effective treatment for all subtypes of organ.8 –10 In Cup, the attached otoliths can be on either
HC-BPPV in this series. Key Words: Horizontal canal, side of the cupula, Cup, canal-sided (Cup-C), or Cup,
benign paroxysmal positional vertigo, forced pro- utricle-sided (Cup-U).8 –9 Geotropic and ageotropic posi-
longed position. tional nystagmus correspond to Can and Cup, respec-
Laryngoscope, 115:1432–1435, 2005 tively.
Although the pathophysiologic mechanism of HC-
BPPV is seemingly easily understood, there have been
From the Department of Otolaryngology (W.-Y.C., S.-C.T., T.-H.Y.), unsatisfactory resolution rates after treatment because of
Songshan Armed Forces Hospital and the Department of Otolaryngology- recently recognized variants. Several repositioning ma-
Head and Neck Surgery (W.-Y.C.), Tri-Service General Hospital, National
Defense Medical Center, Taipei; the School of Nursing (H.-L.L.), Kang-Ning
neuvers such as the Semont maneuver,11 Lempert’s ma-
Junior College of Medical Care and Management, Taipei, and the Depart- neuver (barbecue rotation),12 and forced prolonged posi-
ment of Otolaryngology (X.-X.L.), Keelung Hospital, Department of Health, tion (FPP)13 have been used to either displace otoliths
The Executive Yuan, Keelung, Taiwan, ROC.
from the canal or to dislodge otoliths from the cupula to
Editor’s Note: This Manuscript was accepted for publication April
15, 2005. the utricle for the treatment of HC-BPPV. FPP, which
Send Correspondence to Wen-Yaw Chiou, 10577, F2, No. 48, Lane requires patients to lie on the healthy side for 12 hours, is
155, Kuang Fu North Road, Taipei, Taiwan, ROC. E-mail: chiou. regarded as the most natural and comfortable treat-
wy@msa.hinet.net
ment.10 It is not easy to identify the healthy side; however,
DOI: 10.1097/01.mlg.0000168092.91251.d3 when Cup-U and contralateral Cup-C manifest the same
Laryngoscope 115: August 2005 Chiou et al.: A Single Therapy for HC-BPPV
1432

2. nystagmus pattern, identification is impossible. In this same stronger nystagmus on the left side 2 days after
series, it was found that FPP, with lying on the side of the FPP. Because the patient had a history of left PC-BPPV,
weaker nystagmus rather than on the healthy side, was we speculated that his lesion was in the left ear, so it was
effective for Cup. We hypothesized that FPP detached very likely that the otoliths, detached from the utricle
otoliths from the cupula either to the utricle (Cup-U) or to side, fell into the utricle and then migrated to attach on
the canal (Cup-C), depending on the location of the lesion. the canal side of the cupula. The other case evolved from
The latter could easily be treated with Can later. There- Cup-U to Can and then to Cup-C. The original ageotropic
fore, HC-BPPV not only involved both Can and Cup, ex- positional nystagmus was stronger on the right side and 1
plaining the pathophysiologic mechanism of all subtypes, year after remission, manifested as geotropic nystagmus
but also could be resolved by a single therapy. that was stronger on the right side. A right HC lesion was
The purpose of this study was to effectively treat all implicated. Nine days after successful treatment of Can
subtypes of HC-BPPV by way of a single therapy approach with FPP, stronger ageotropic positional nystagmus was
that is based on positional nystagmus pattern and evolution. noted on the left side. We speculated that otoliths trans-
ferred and attached to the canal side of the right cupula.
PATIENTS AND METHODS
From July 1999 to June 2003, 89 patients (48 females and DISCUSSION
41 males, age 23-88 years; mean SD 57.8 16.1) with HC- In 1985, it was first noted that BPPV not only in-
BPPV of a total 283 BPPV patients were seen at our outpatient volves the PC but also the HC (HC-Can) or even the
department. Either geotropic or ageotropic bilateral horizontal anterior canal.15 Seven patients presented with bilateral
nystagmus was noted on the supine to the head-lateral test. The
horizontal geotropic nystagmus in the supine position
test was performed with patients in the supine position with head
up 30 degrees, followed by turning over to either side. Videonys-
with the head turned to either side. Ten years later, two
tagmography was used to record and analyze positional nystag- representative papers regarding Cup of HC (HC-Cup)
mus. All patients were treated with FPP, lying on the side of were published. In 1995, a study reported three cases
weaker nystagmus for 12 hours. The patients were followed up by presenting with persistent bilateral horizontal ageotropic
the outpatient department 2 days after each therapy and until nystagmus after treatment.8 The author suggested that
the symptoms and nystagmus resolved. We adopted Epley’s14 otoliths moved from the utricle and attached to the utricle
definition of complete resolution, that is, no further positional side of the cupula. The next year, another study reported
vertigo reported for 1 month after the last treatment. two cases presenting with bilateral horizontal geotropic
nystagmus that transformed to ageotropic nystagmus
RESULTS during treatment.9 The author suggested that otoliths
There were 89 patients with HC-BPPV, including 49 shifted from the canal to attach to the canal side of the
caused by Can and 40 by Cup. All symptoms resolved after utricle. These two authors believed that only Cup could
FPP therapy in four visits or less (68, 10, 6, and 5 patients explain ageotropic nystagmus, and that, because of their
in 1, 2, 3, and 4 treatment sessions, respectively). The case patients’ past history of PC-BPPV and HC-BPPV, Cup
distribution is shown in Figure 1. In 11 of 40 Cup patients, could possibly happen on the utricle and canal sides of the
positional nystagmus was transformed from ageotropic to cupula, respectively.
geotropic after treatment with FPP. We speculated that Can and Cup correspond to the mechanisms of geo-
the original lesion was Cup-C, which then shifted to Can. tropic and ageotropic bilateral horizontal positional nys-
The stronger side of the geotropic nystagmus was on the tagmus, respectively (Fig. 2). Therefore, there are two
same side as the original Cup-C; FPP treatment was then subtypes of HC-BPPV, which can be designated HC-Can
changed to lying on the other side. and HC-Cup according to the presenting positional nys-
The other 29 Cup cases were presumed to be Cup-U tagmus. As per Ewald’s Law of Vestibular Function,7 en-
because 27 of them experienced resolution of their nystag- dolymph flowing toward the utricle in the HC causes
mus after FPP. The other two cases appeared to be more greater stimulation that will cause nystagmus toward
complicated. One changed from Cup-U to Cup-C with the that side. In HC-Can, while turning the head to either
side, horizontal nystagmus will be directed toward the
ground (i.e., geotropically). The further in the canal that
otoliths travel during head turning, the stronger is the
nystagmus generated, which is also on the lesion side. In
HC-Cup, while turning the head to either side, horizontal
nystagmus will be directed toward the other side (i.e.,
ageotropically). While turning the head to either side,
attached otoliths on the upper side rather than the under-
side will result in stronger nystagmus, which is also on the
lesion side.8
Figure 3 shows how FPP works when used as a single
therapy for all subtypes of HC-BPPV. When lying on the
Fig. 1. Case distribution and subtypes of horizontal canal benign side of the weaker nystagmus, gravitational directional
paroxysmal positional vertigo (HC-BPPV). HC-Can represents
canalolithiasis. HC-Cup represents cupulolithiasis. Cup-U and
change makes otoliths move as expected. Otoliths migrate
Cup-C represent cupulolithiasis, utricle-sided and canal-sided, re- to the utricle in the Can, and detach from the cupula to the
spectively. utricle and canal in utricle-sided (Cup-U) Cup and con-
Laryngoscope 115: August 2005 Chiou et al.: A Single Therapy for HC-BPPV
1433

3. drawback was that those patients might more likely de-
velop PC-BPPV. Posttreatment transition from HC to PC
was reported in 4 of 36 patients treated with barbecue
rotation versus 2 of 63 patients treated with FPP.5 In our
series, this transition occurred in 1 of 89 patients 20 days
after FPP. Furthermore, in cases where the ageotropic
nystagmus pattern of Cup-U and contralateral Cup-C
were the same, the healthy side might not be decided
correctly. So far, FPP has not only been effective and
gentle but patient compliance has also been good.
Moreover, ipsilateral Cup-U and contralateral
Cup-C, two subtypes of HC-Cup, had the same stronger
side of ageotropic nystagmus (Fig. 2). It was impossible to
identify the healthy ear in ageotropic nystagmus. Perhaps
Fig. 2. Geotropic and ageotropic bilateral horizontal positional nys- this is why other studies have had a lower resolution rate
tagmus induced by canalolithiasis and cupulolithiasis of horizontal
canal benign paroxysmal positional vertigo (HC-BPPV). Enlarged
of HC-BPPV treatment. In a large, published series, the
horizontal semicircular canals are shown from leg to head with success rate was 66% (24/36) after barbecue rotation and
patient lying supine and turning on either side. Sphere represents 73% (46/63) after FPP.6 Rather than treating blindly, we
otoliths in the canal (Can) moving to the utricle by gravitational modified FPP by having patients lie on the side of weaker
directional change. Square and triangle represent utricle-sided nystagmus and then following up its evolution. The same
(Cup-U) and contralateral canal-sided (Cup-C) otoliths detaching
from the cupula to the utricle and canal, respectively. Arrow in the goal, to detach the utricle-sided or contralateral canal-
grid represents the nystagmus direction with the patient supine and sided otoliths from the cupula and to displace them to
facing the examiner and turning to either side. Heavier arrow de- either the utricle or the canal, respectively, could be
notes stronger nystagmus. achieved by lying on the side of the weaker ageotropic
nystagmus. Once the nystagmus shifted to geotropic on
follow-up examinations, it was treated as Can. Thus, it
tralaterally in canal-sided (Cup-C) Cup, respectively. In
cannot be overemphasized that close follow-up of the evo-
particular, Cup-C was treated by lying on one side, and
lution of nystagmus direction and strength was the basis
then the other, once it evolved to the Can subtype.
for improvement in the resolution rate.
Occasionally, the side of stronger nystagmus (re-
quired for correct FPP) could not be identified without
videonystagmography to identify the diseased ear. A past CONCLUSION
history of PC-BPPV helped to identify the lesion side of The incidence and mechanism of HC-BPPV have be-
HC-BPPV. In some cases, patients who were obese or come increasingly recognized in recent years. In our series
having spinal problems could not lie on one side at home. lasting 4 years, HC-BPPV accounted for 31% of BPPV
In those cases, Lempert’s maneuver (barbecue rotation) cases seen. We can rationally classify HC-BPPV into HC-
could be performed in the outpatient department by turn- Can and HC-Cup according to whether bilateral horizon-
ing to the healthy side with three 90 degree turns. A tal nystagmus is geotropic or ageotropic. Furthermore,
HC-Cup can be separated into Cup-U and Cup-C on the
basis of whether ageotropic nystagmus resolves or be-
comes geotropic after FPP therapy. With this division in
mind, and knowing the evolution of bilateral horizontal
positional nystagmus, ineffective treatment can be
avoided. The excellent results of our study substantiate
our hypothesis that a single FPP session, with lying on the
side of weaker nystagmus, is effective treatment for all
subtypes of HC-BPPV.
Acknowledgments
The authors thank Hsing-Won Wang, PhD, for re-
viewing this manuscript.
Fig. 3. Forced prolonged position (FPP) as a single therapy for
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