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unilateral vestibular hypofunction ( uvh ) is a vestibular disorder in which a total or 
 partial decrease in vestibular function is observed , which is characterized by abnormally 
 reduced responses to the caloric test unilaterally .
disorders , such as vestibular 
 schwannoma , vestibular neuritis , infections , and trauma affecting the inner ear , that can 
 lead to destruction of the sensorineural epithelium of the membranous labyrinth and/or 
 vestibular nerve fibers are diagnosed as uvh .
besides dizziness , the clinical picture of uvh 
 may include nystagmus , ocular torsion , oscillopsia , postural instability , gait disorders , 
 anxiety , depression , and fear .
uvh patients commonly share the same symptoms , in spite of 
 differences regarding the etiology , onset , and clinical findings of dysfunction or the type 
 and extent of the vestibular deficit1 , 2 . for a person with vestibular hypofunction , the main aims of treatment by the health - care 
 providers are restoring function or preventing further dysfunction . to deliver an effective 
 rehabilitation program to them , these patients need to be evaluated and diagnosed properly . 

routine diagnosis of vestibular hypofunction has been based on the results of conventional 
 methods such as the head thrust test ( htt ) , the horizontal head - shaking nystagmus test , and 
 the caloric test3 .
other than these tests , 
 previous studies have used a variety of outcome measures including dynamic posturography , 
 the motion sensitivity quotient ( for rapid head movements ) , and the self assessed dizziness 
 handicap inventory ( dhi - jacobson and newman , 1990 ) .
apart from these , advanced techniques 
 like electronystagmography ( eng ) , videonystagmography ( vng ) , and rotational chair tests have 
 also been used for measurement of vestibulo - ocular function , and computerized dynamic 
 posturography ( cdp ) incorporates all three modalities to effect an assessment of static and 
 dynamic stance .
the sensory organization test ( sot ) protocol of cdp evaluates the patient s 
 ability to use the three systems that are chiefly responsible for maintaining upright , 
 volitional , balanced posture : vision , the vestibular system , and proprioception .
but the 
 cost and time required to perform these tests are factors that keep them from being used in 
 general clinics4,5,6 .
even though the sensitivity of the htt for identifying individuals with 
 vestibular hypofunction is relatively good , there are studies that prove that it is more 
 sensitive in patients with bilateral vestibular hypofunction ( bvh ) than in patients with 
 uvh7 .
while various clinical measures 
 have been developed to document uvh , the limitations of these tests are in the lack of 
 specificity for screening the unilateral vestibular deficit .
thus , there is a need for a 
 simple quantitative objective test to screen for unilateral vestibular hypofunction , and for 
 this reason , the sideways stepping test ( sst ) or fukuda stepping test ( fst ) could be a valid 
 and reliable diagnostic tool for detecting uvh .
therefore , the purpose of this study was to 
 investigate whether sst is both a sensitive and specific test for detection of uvh as it is 
 effective , safe , and economical and therefore can be used widely throughout the world .
the present study was conducted in a private otolaryngology ( ent ) department in jeddah , 
 saudi arabia .
twenty - eight adults participated in the study ( 15 male and 13 females ) . 
 written informed consent
the 
 study was conducted after obtaining approval from the institutional ethics review board of 
 the faculty of applied medical sciences , king abdul aziz university , jeddah .
all the 
 participants were required to complete and clear the following comprehensive screening 
 tests : cervical instability test , modified vertebral artery test ( mvat ) , spontaneous 
 ( resting ) nystagmus test , smooth pursuit test , saccadic eye movement test , and vestibular 
 ocular reflex ( vor ) cancellation test to rule out all central mediated problems . only 
 subjects complaining of peripheral dizziness who were between the ages of 25 and 55  years 
 old and able to ambulate independently were included in the study .
subjects with central 
 mediated problems such as stroke , acquired brain injury , multiple sclerosis , or peripheral 
 neuropathy were excluded from the study .
moreover , subjects who could not ambulate 
 independently , were blind , were profoundly deaf or had cervical spine pathology were also 
 excluded .
the major outcome variables for confirming the presence of uvh were obtained by 
 the sst and the gold standard test , which is head - shaking nystagmus hsn test using video 
 electronystagmography ( veng ) .
the patients were evaluated for uvh , starting 
 first with the sst . in this test
, the subject is asked to stand with their feet together and 
 their hands by their sides .
the subject is then asked to close his / her eyes or is 
 blindfolded .
the test is positive if there is involuntary leaning to one side and hip sway . 

sometimes , the subject lifts a hand to compensate . in that case , the subject is asked to 
 take two steps sideways and stop , first with the eyes open and then with the eyes closed or 
 blindfolded .
the test was positive if there is any involuntary swaying and/or any steps 
 taken to compensate .
the suject is then asked to jog on the spot for 30 seconds with the 
 eyes closed or blindfolded .
the test is positive if there is 
 any involuntary drifting to one side or , in some cases , forward or backward .
after finishing the sst , the subject is then evaluated with the hsn test using veng , which 
 is the gold standard test used to determine whether a vestibular ( inner ear ) disease may be 
 the causative factor for a balance or dizziness problem and is one of the only tests 
 available today that can distinguish between a unilateral ( one ear ) and bilateral ( both 
 ears ) vestibular dysfunction .
veng testing consists of a series of tests designed to 
 document a person s ability to follow visual objects with their eyes and how well the eyes 
 respond to information from the vestibular system . to monitor the movements of the eyes , 

however , 
 during veng testing , the therapist moves the patient s head and body into various positions 
 to make sure that there are no inappropriate eye movements ( nystagmus ) , when the patient s 
 head is in different positions .
hsn is a latent spontaneous vestibular nystagmus that can be 
 recorded with veng . during the test for hsn
, the examiner turns the subject s head by about 
 45 degrees horizontally about 20 times .
hsn is defined as the occurrence of at least 5 beats 
 of nystagmus immediately after the head - shaking maneuver , which should be performed with 
 frenzel veng goggles .
there is good evidence that hsn reflects a dynamic ( peripheral and/or 
 central vestibular ) asymmetry of the velocity storage mechanism . in peripheral lesions
, the 
 ipsilateral dynamic vor deficits can lead to an asymmetric accumulation within the velocity 
 storage , the discharge of which determines the direction of hsn , usually toward the 
 unaffected ear9 . the results of both tests 
 were then compared with each other ; the results should be the same in both tests . 

data were analyzed using spss for windows version 19.0 ( spss , inc . , chicago , il , usa ) . 

frequencies and relative frequencies were computed for nominal variables , and means and 
 standard deviations ( sd ) were computed for the continuous variables .
the  test 
 of independence was used to assess the relationship between the sst and the gold standard 
 hsn test using veng .
sensitivity , specificity , positive predictive value and negative predictive value also were 
 measured .
the baseline frequency characteristics of the study group are presented in table 1table 1.baseline frequency characteristic of the study group ( n = 28)validfrequencypercentsexmale1553.6%female1346.4%hsnpositive1346.4%negative1553.6%sstpositive1657.1%negative1242.9% .
the results showed that the sst is strongly correlated with the gold standard 
 hsn test using veng ( r = 0.81 , p<0.001 ) .
a stepwise linear regression was conducted to 
 determine the effect of the sst on the gold standard ( hsn test using veng ) results 
 ( r = 0.65 , p < 0.001 ) .
sixty - five percent of the variability in the gold 
 standard test result was explained by its relationship to the sst .
the data used to measure 
 the sensitivity and specificity in this study are presented in tables 2 and 
 3table 2.data for sensitivity and specificitytrue positive ( tp)false negative ( fn)13 ( 46%)0 ( 0%)false positive ( fp ) true negative ( tn)3 ( 11%)12 ( 43%)table 3.summary of sensitivity , specificity , ppv , and npv resultspatients with uvh by the hsn test using 
 vengcondition positivecondition negativeoutcome positivetrue positive ( tp ) = 13false positive ( fp ) = 3positive predictive value 81%outcome negativefalse negative ( fn ) = 0true negative ( tn ) = 12negative predictive value 100%sensitivity 100%specificity 80% , and the results show that sst has very high sensitivity ( 100% ) and high 
 specificity ( 80% ) .
the primary purpose of the current study was to examine whether the sst could be used to 
 identify patients with uvh as an alternate method to the hsn test using veng .
even though 
 there are many tests in practice for detecting vestibular hypofunction , all of them are used 
 to diagnose a bilateral vestibular hypofunction rather than uvh . as far as we know , this is 
 the first paper published based on the use of sst , which is reliable , easy to apply , and 
 cost effective , instead of the hsn test using veng to diagnose a patient with uvh .
uvh is currently diagnosed using veng , but some studies have shown that there is another 
 test that can be used for diagnosing uvh , namely , the sst . in 1959 , fukuda proposed a 
 variation of the tretversuch test of unterberger ( 1938 ) and the waltzing 
 test of hirsch ( 1940 ) named the stepping test ; that test is intended to 
 identify the weaker of the labyrinths ( not necessarily the side with the lesion ) by 
 direction of rotation of a patient while walking on the spot with the eyes closed10 . actually , some researchers have suggested 
 use of the sst in combination with other clinical tests ( e.g. , electronystagmography , 
 rotational chair , head thrust , and head shaking tests ) in the assessment of vestibular 
 pathologies rather than using it in isolation11 , 
 12 .
therefore , the purpose of this 
 study was to investigate whether the sst can be considered both a sensitive and specific 
 test for detection of uvh . based on our study results , we found a strong positive relationship between the sst and the 
 hsn test using veng ( 65% ) , which indicates that the sst is an efficient test in the 
 diagnosis of uvh . also , we found that the sst is both sensitive ( able to pick up the 
 presence of any uvh in a person who has it ) and specific ( able to pick up the absence of any 
 uvh in a person who does not have it )
so , it can be used to include or exclude the 
 dysfunction , but the results were better when it was used for inclusion . when using the hsn 
 test using veng as the standard reference , our results showed adequate sensitivity and 
 specificity to support the use of sst as a screening test for unilateral vestibular 
 hypofunction . a prospective study by zhang et al .
concluded that the fst was unreliable in identifying 
 the lesion side in acute vestibular dysfunction12 . even though some other studies also reported the same results and 
 conclusions13 , 14 , our study we found that the sst is a reliable and valid tool for 
 detection of uvh .
the possible reasons for higher sst sensitivity and specificity in our 
 study than in other studies is the difference in the studied populations , with more subjects 
 with uvh in our sample , and the previous studies not being compared with any objective 
 standard method of testing .
second , there was great difficulty accessing patients and veng 
 equipment , as there are very few otolaryngology ( ent ) departments that are specialized in 
 our area .
third , we were unable to take pictures of the subjects for personal privacy 
 reasons . therefore , we recommend that future research should be performed with a larger 
 number of subjects , should be experimental rather than an observational , and should measure 
 the sensitivity and specificity of the sst with regard to its ability to diagnose the side 
 of the dysfunction . in conclusion , the study results showed that the sst is useful as an objective measure in 
 the evaluation of uvh in parallel with the hsn test using veng .
so the sst can be used as an 
 alternative to the hsn test using veng for detection of uvh .
[ purpose ] this study investigated to determine whether the sideways stepping test ( sst ) 
 is a useful test to detect unilateral vestibular hypofunction ( uvh ) . [ subjects and 
 methods ] twenty - eight subjects including both male and females between the ages of 25 and 
 55 who had been diagnosed with uvh were recruited for the study . 
 all the subjects were 
 tested with the sst and followed by the head - shaking nystagmus ( hsn ) test using video 
 electronystagmography ( veng ) to confirm the presence of uvh . 
 the results of both tests 
 were then compared with each other to determine the correlation , sensitivity , and 
 specificity . 
 [ results ] the results showed that the sst is strongly correlated with the 
 gold standard hsn test using veng and is highly sensitive and specific . 
 [ conclusion ] the 
 present study showed that the sst is a highly valid test that can be used as an 
 alternative method to the gold standard hsn test using veng in detecting uvh .