Balance ability in patients with benign paroxysmal positional vertigo

Otolaryngology–Head and Neck Surgery (2006) 135, 534-540

ORIGINAL RESEARCH

Balance ability in patients with benign

paroxysmal positional vertigo

Wen-Ching Chang, Li-Chi Hsu, MD, Yea-Ru Yang, PhD,
and Ray-Yau Wang, PhD, Taipei, Taiwan
OBJECTIVE: The purpose of the study was to investigate thebalance ability of the patients with benign paroxysmal positionalvertigo (BPPV).STUDY DESIGN AND SETTING: Twenty-three patients(63.3 � 9.2 years of age) with a diagnosis of unilateral posteriorsemicircular canal BPPV were recruited. Static balance was mea-sured in 4 conditions with eyes open and eyes closed: stance onfirm surface, stance on foam surface, left leg stance, and right legstance. Dynamic balance was measured in tandem walk test. Dataof the patients with BPPV were compared to age-matched normvalues of the healthy adults.RESULTS: The patients with BPPV demonstrated greater swayvelocity in stance on foam surface with eyes closed (P � 0.05), insingle leg stance with eyes closed (P � 0.001), and in tandem walktest (P � 0.05) compared to the healthy adults.CONCLUSIONS: Patients with BPPV demonstrated impairedstatic and dynamic balance ability particularly when deprivingvisual and changing proprioceptive inputs.SIGNIFICANCE: Clinically, in addition to canalith reposition-ing maneuver, balance retraining on different conditions may be auseful adjunct to treatment for patients with BPPV.© 2006 American Academy of Otolaryngology–Head and NeckSurgery Foundation. All rights reserved.

The vestibular system plays an important role in main-taining balance and is also critical for optimal function.

It provides information about the linear and angular accel-eration of the head and detects head position relative to thegravitational axis. In addition, the vestibular system assistsin stabilizing gaze via vestibulo-ocular reflex during rapid

From the Section of Neurovascular Disease, Institute of Neurology,Taipei Veterans General Hospital, Taipei, Taiwan (Dr Hsu); NationalYang-Ming University School of Medicine, Shih-Pai, Taipei, Taiwan (DrHsu); and Institute and Faculty of Physical Therapy, National Yang-MingUniversity, Shih-Pai, Taipei, Taiwan (Drs Yang, Wang, and Ms Chang).

Supported by the National Science Council of the Republic of China,
grant 92-2314-B-010-021.
0194-5998/$32.00 © 2006 American Academy of Otolaryngology–Head and Necdoi:10.1016/j.otohns.2005.10.001

head movement. The system is also involved in the head andtrunk control via vestibulocollic reflex and vestibulospinalreflex for upright posture and balance.1 Patients with ves-tibular dysfunction demonstrate impaired balance ability tomaintain head stability and adjusting upright posture.

Among vestibular disorders, benign paroxysmal posi-tional vertigo (BPPV) is considered the most common pe-ripheral vestibular disorder.2 Most BPPV patients are idio-pathic—that accounts for about 50% to 70% of all cases.The second most common cause of the BPPV is headtrauma, representing 7% to 17% of all BPPV cases.3 Theonset age of the disorder occurred mostly between aged 50to 70 years.3,4

Patients with BPPV usually suffer from paroxysmal at-tacks of positional vertigo and nystagmus during specificmovements. In addition, many patients also complain oflightheadedness, nausea, imbalance, and standing and walk-ing disturbances. The most common provoking movementsinclude rolling in bed, lying down, sitting up, extending theneck to look up, and bending forward. Various pathophys-iological mechanisms have been proposed to explain par-oxysmal positional vertigo. Parnes and McClure5 in 1992hypothesized “Canalithiasis,” free-floating debris movingwithin a semicircular canal. Movement of the debris wouldcause the endolymph to move away from the cupula, caus-ing cupular deflection and inappropriate excitation.

According to previous studies, patients with BPPV haveshown impaired balance ability in increased anteroposteriorrather than mediolateral body sway after provocative head

Reprint requests: Ray-Yau Wang, Professor, Institute and Faculty ofPhysical Therapy, National Yang-Ming University, 155, Sec 2, Li NongSt., Shih-Pai, Taipei, Taiwan.

E-mail address: [email protected].

k Surgery Foundation. All rights reserved.

535Chang et al Balance ability in patients with benign paroxysmal positional vertigo

movement as measured by static posturography.6 In anothersimilar study, however, significant increase in body swaywas noted both on the lateral and anteroposterior planes.7

Furthermore, patients with BPPV also have shown poorsensory organization ability detected by means of dynamicposturography.8,9

No existing studies identified clearly the balance impair-ments of the patients with BPPV during the complex andfunctional movement tasks. Therefore, we investigated thebalance ability in patients with active, non-treated BPPVduring stance on uneven surface, single leg stance, andwalking. The present study was part of ongoing, prospec-tive, longitudinal research to evaluate the effect of vestibu-lar rehabilitation therapy in addition to canalith reposition-ing maneuver (CRM)10 in patients with BPPV.

PATIENTS AND METHODS

SubjectsThe study protocol was reviewed and approved by theInstitutional Review Board of the Taipei Veterans GeneralHospital. Patients with active, idiopathic unilateral posteriorsemicircular canal BPPV, diagnosed by a neurologist fromthe Taipei Veterans General Hospital dizzy clinics, wererecruited. The selected patients in this study underwentclinical examinations consisting of medical history, oculo-motor examinations with an infrared video recording sys-tem, and bi-thermal caloric test. Oculomotor examinationsincluding saccade and pursuit tests were used to detectgaze-evoked nystagmus, abnormal amplitude and timing ofvestibulo-ocular reflex. The examinations were also used todifferentiate central or peripheral vestibular lesions. Calorictest with bi-thermal air stimulation was used to evaluateperipheral vestibular hypofunction.

The diagnostic criteria for posterior semicircular canalBPPV of the present study were the presence of positionalvertigo and a typical torsional, upbeating nystagmus pro-voked by Hallpike-Dix maneuver.11 For the provoked nys-

Table 1

Static balance ability of the patients with BPPV compa

Static balance test

Stance on firm surface (EO) SV (deg/sec)Stance on firm surface (EC) SV (deg/sec)Stance on foam surface (EO) SV (deg/sec)Stance on foam surface (EC) SV (deg/sec)Left leg stance (EO) SV (deg/sec)Left leg stance (EC) SV (deg/sec)Right leg stance (EO) SV (deg/sec)Right leg stance (EC) SV (deg/sec)

EO, eyes open; EC, eyes closed; SV, sway velocity.

tagmus, it was delayed onset (latency � 2-40 sec), transi-

tory (�60 sec), and reversed while the patient resumed theoriginal sitting position.

The anterior and horizontal types of BPPV were ex-cluded from the present study by their characteristic nys-tagmus provoked by the Hallpike-Dix maneuver. In addition,other possible causes of secondary BPPV or episodic briefvertigo mimicking BPPV, such as head trauma, Ménière’sdisease, vestibular neuritis, and labyrinthitis, were excludedby appropriate history and neuro-otological examinations.Patients with neurological pathology (CNS, PNS), proprio-ceptive impairment, cardiovascular diseases, or orthopedicproblems (osteoarthritis of knee, lower extremity deformity,cervical instability) were also excluded from the presentstudy.

Figure 1 Mean sway velocity for all patients in stance on firmsurface, stance on foam surface, left leg stance, and right leg stancetest with eyes open condition. With eyes open, patients with BPPVshowed greater sway velocity in stance on foam surface and insingle leg standing compared to standing on firm surface (P �0.001) and also demonstrated greater sway velocity in left legstance than stance on foam surface (P � 0.001). *P � 0.001,compared to stance on firm surface test. �P � 0.001, compared to

ith age-matched healthy adults

tients with BPPV(mean � SD)

Age-matchednorm value P value

0.17 � 0.08 0.30 �0.0010.17 � 0.12 0.35 �0.0010.69 � 0.18 0.712.79 � 1.53 1.74 �0.052.38 � 2.17 1.11 �0.05

10.19 � 3.16 3.23 �0.0011.31 � 1.64 1.10

10.97 � 2.41 3.39 �0.001

red w

Pa

stance on foam surface test.

foam surface test.

Age-matched norm value is indicated by solid horizontal bar.

536 Otolaryngology–Head and Neck Surgery, Vol 135, No 4, October 2006

Measurements

Balance ability of the patients in the present study wasmeasured by the Balance Master System (Neurocom Inter-national, Inc., Clackamas, OR) after diagnosis was confirmed.This system is a rehabilitation tool designed to provide quan-titative assessment of static and dynamic balance performanceand position of the center of gravity. Concurrent validity ofthe Balance Master data has been established for patientswith stroke.12 Test–retest reliability estimates for static anddynamic balance tests of Balance Master were found to bemoderate to high.12 There were 2 force plates positioned sideby side with transducers mounted along the anterior–posteriorcenter line of each plate. Force sensors under the force platesmeasure the vertical forces exerted by the subject’s feet. Acable carries the information from the dual force plates tothe computer. A computer with version 7.0 Balance MasterSystem software analyzes the force information. The sub-jects stood on the dual force plates with standard footposition and faced the screen. All of the measurements wereexecuted by the same evaluator.

Static balance was measured as sway velocity in 4conditions: stance on firm surface, stance on foam sur-face, left leg stance, and right leg stance. Each conditionwas carried out with both eyes open and both eyes closed.For safety, 2 assistants stood by in case the patients lost

r stance on foam surface with eyes open (A) and eyes closed (B).

Figure 2 Mean sway velocity for all patients in stance on firmsurface, stance on foam surface, left leg stance, and right leg stancetest with eyes closed condition. In eyes closed conditions, patientswith BPPV demonstrated greater sway velocity in stance on foamsurface and single leg standing compared to stance on firm surface(P � 0.001) and greater sway velocity in single leg stance thanstance on foam surface (P � 0.001). *P � 0.001, compared tostance on firm surface test. �P � 0.001, compared to stance on

Figure 3 Distribution of the sway velocity of individual subjects unde


their balance during test. All patients were instructed tostand upright as steadily as possible. Each test consistedof 3 trials, each lasting for 10 sec. If a subject momen-tarily touched the force plate with the raised foot duringthe single leg stance test, data collection was not inter-rupted. If a subject moved the raised foot down orstepped off the force plate for �1 sec, the trial wasstopped and the sway velocity was assigned and recordedas 12.0 (the maximal score in the system). Sway velocityis the ratio of distance in degrees traveled by the centerof gravity to the time of the trial (10 sec). Sway velocity(°/sec) is a measure of the sway severity.13

Dynamic balance was measured as walking speed andend sway velocity in the tandem walk test. Subjects wereinstructed to stand heel-to-toe steadily as the starting posi-tion. When the “Go” instruction appeared on the screen, allsubjects tandem walked as quickly as possible and heldsteady at the end of the force plate. The test consisted of 3trials, each lasting 10 sec. If a subject stepped off the forceplate or was improperly positioned, the trial was interruptedand the sway velocity was recorded as 12.0. Walking speed(cm/sec) is the velocity of forward progression. End sway

Figure 4 Distribution of the sway velocity of individual subAge-matched norm value is indicated by solid horizontal bar.

velocity (°/sec) was measured after forward progression

stopped that required rapid deceleration of the center ofgravity.13

Statistical AnalysisAll results were expressed as mean � SD. Data of thepatients with BPPV were compared to age-matched normvalues of the healthy adults. Statistical analysis of meandifferences was carried out by using the one sample t-test(SPSS 10.0). We also used repeated measures to comparethe sway velocity under different conditions with eyes openand eyes closed conditions. The significant level was set at0.05.

RESULTS

Twenty-three patients (12 males, 11 females) with unilateralposterior semicircular canal BPPV with mean age of 63.3 �9.2 (range � 48-78) participated in the study.

Patients with BPPV demonstrated greater sway veloc-ity than healthy adults in the stance on foam surface witheyes closed (P � 0.05) and in single leg stance with eyes

under left leg stance with eyes open (A) and eyes closed (B).
jects
closed (P � 0.001). The sway velocity was less in pa-


tients with BPPV than in the healthy adults during thestance on firm surface with eyes open and eyes closed (P �0.001) (Table 1).

With eyes open, patients with BPPV showed greater swayvelocity in stance on foam surface and in single leg standingcompared to standing on firm surface (P � 0.001) and alsodemonstrated greater sway velocity in left leg stance thanstance on foam surface (P � 0.001) (Fig 1). In eyes closedconditions, patients with BPPV demonstrated greater swayvelocity in stance on foam surface and single leg standingcompared to stance on firm surface (P � 0.001) and greatersway velocity in single leg stance than stance on foam surface(P � 0.001) (Fig 2). Figures 3 to 6 illustrate sway velocity ofindividual subjects under different conditions.

Greater endpoint sway velocity (P � 0.05) and slowerwalking speed (P � 0.001) in tandem walk test were alsonoted in patients with BPPV when compared to the healthyadults (Table 2).

DISCUSSION

Patients with active, non-treated BPPV showed impair-

Figure 5 Distribution of the sway velocity of individual subAge-matched norm value is indicated by solid horizontal bar.

ments in balance as indicated by a greater sway velocity

when they stood on uneven surface or stood with one legwithout visual inputs, compared to that of healthy adults.With depriving visual and changing proprioceptive inputs,patients with BPPV needed to rely heavily on the vestibularsystem for balance. The lack of accurate vestibular infor-mation from one side may cause ineffective sensory orga-nization and abnormal vestibulospinal output and thus resultin increased sway in such conditions. Patients with uncom-pensated unilateral peripheral vestibular dysfunction mayhave difficulty maintaining an upright posture when bothvisual and proprioceptive inputs are altered.14 Patients withBPPV, however, demonstrated less sway velocity during thestance on the firm surface with eyes open and eyes closed.In these conditions, patients relied heavily and successfullyon visual or proprioceptive inputs to maintain upright pos-ture as steadily as possible. Patients with BPPV used thesesensory inputs to compensate for vestibular dysfunction.

In previous studies, DiGirolamo et al8 found patientswith BPPV showed impairments of postural control in con-ditions with altering either proprioceptive, visual or both in-puts during the sensory organization test. Blatt et al9 foundpatients with BPPV showed increased postural sway specifi-cally in conditions with altering proprioceptive inputs com-

nder right leg stance with eyes open (A) and eyes closed (B).
jects u
bined with altering or depriving visual inputs as measured


by computerized dynamic posturography. It can be shownthat patients with BPPV have normal stability in stableplatform with or without altering visual inputs. These pa-tients have below-normal stability in altering proprioceptiveand depriving visual inputs. Our study also confirmed theprevious findings. With depriving visual and changed pro-prioception inputs, patients with BPPV demonstrated im-paired static standing balance.

We also found that patients with BPPV showed greatersway velocity in the single leg standing than standing withboth feet on a firm or foam surface. In single leg stance test,there were narrower base of support and greater challenge to

Figure 6 Distribution of the sway velocity (A) and walking spevalue is indicated by solid horizontal bar.

Table 2

Dynamic balance ability of the patients with BPPV com

Dynamicbalance test

Patie(m

Tandem walk SV (deg/sec)Tandem walk WS (cm/sec) 1

SV, sway velocity; WS, walking speed.

standing stability. Patients with BPPV needed to pay moreeffort on sensory organization and muscle cocontraction tomaintain standing balance. With eyes open, less sway wasnoted, even not significantly, when standing on right legthan on left leg. It might be due to the right dominant lowerextremity of our patients. Nevertheless, under eyes closedcondition, patients with BPPV showed greater sway veloc-ity compared to the age-matched norm values of the healthyadults. The majority of the patients showed difficulty inmaintaining balance during single leg stance with eyesclosed test. The visual and proprioceptive inputs were moreimportant for patients with BPPV to use than those for

of individual subjects under tandem walk test. Age-matched norm

d with age-matched healthy adults

ith BPPV� SD)

Age-matchednorm value P value

2.08 4.40 �0.056.74 31.68 �0.001

ed (B)

pare

nts wean

5.48 �9.72 �


healthy adults. It is evident that single leg standing balanceis difficult for subjects with BPPV. It is therefore beneficialto the patients with vestibular disorders that vestibular re-habilitation includes specific exercises to improve single legstanding balance.15,16

During tandem walk test, patients with BPPV showedslower walking speed and greater end sway velocity com-pared to that of the healthy adults. Because of the narrowbase of support, patients needed to slow down for dynamicbalance. At the end of tandem walk, deceleration of thecenter of gravity was required to hold the body steadily.Greater end sway velocity observed in the patients withBPPV showed the vestibular dysfunction to detect lineardeceleration and thus result in abnormal vestibulospinaloutput to stabilize trunk. Lacour et al17 have shown thatproducing a unilateral vestibular neurotomy in baboons in-duces asymmetrical excitability in ipsilateral and contralat-eral spinal reflexes. Impairment of the function of vestibu-lospinal reflex is believed to contribute to postural disturbancesin patients with peripheral vestibular disorders.

In summary, our study showed that balance function wasimpaired in patients with BPPV during the complex andfunctional movement tasks by means of the Balance Mastersystem. Patients with unilateral BPPV demonstrated im-paired static and dynamic balance ability particularly whenthe visual and proprioceptive inputs were changed. Clini-cally, patients with BPPV are usually referred for CRM thatis effective on symptoms relief and balance.9,10 Not allpatients improved to normal postural stability after CRM.9

If a patient still showed balance impairment even afterreceiving CRM, balance retraining with altering visual andproprioceptive inputs to emphasize vestibular function maybe a useful adjunct to treatment for patients with BPPV.

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Balance ability in patients with benign paroxysmal positional vertigo

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