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July2010 Vol.47 Issue:      3 (Supp.) Table of Contents
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The Role of Brainstem Auditory Evoked Potentials, Electronystagmography and Transcranial Doppler in Evaluation of Patients with Vertigo

Tarek A. Rageh1, Enas S. Mohamed2, Amal M. Elattar2

 

Departments of Neurology and Psychiatry1, ENT2, Assiut University; Egypt

 



ABSTRACT

Background: vertigo may be a warning sign of impending vertebrobasilar stroke. Objective: To investigate the role of brain stem auditory evoked potential (BAEP), electronystagmography (ENG) studies and results of transcranial Doppler (TCD) in patients with vertigo of vertebrobasilar origin and patients with vertigo of non-vertebrobasilar origin. Methods: Twenty five patients with vertigo aged 40-65 and 10 controls with no history of vertigo were studied. The patients were subjected to clinical neuropsychiatric evaluation, basic audiological evaluation, BAEP, ENG and TCD. Patients were divided into 2 groups depending on history, neurological examination and laboratory investigations. Group I includes 11 patients with vertebrobasilar insufficiency (VBI), group II includes 14 patients with no manifestation of vertebrobasilar insufficiency (non-VBI). Results: In VBI group ENG was abnormal in 81.8%. TCD 72.7%, BAEP 63.6% the three tests were abnormal in 63%. In non VBI group, ENG was abnormal in 64.2%, TCD 21.4% BAEP 14.2%. Positive correlation was found between delayed latencies of wave III & V of ABR response and pulsatility index of vertebrobasilar arteries. Conclusion: TCD combined with BAEP and ENG can lead to early recognitions of patients at risk of vertebrobasilar stroke. Hence appropriate investigations and treatment could be done to prevent this outcome. [Egypt J Neurol Psychiat Neurosurg.  2010; 47(3): 511-518]

 

Key Words: vertigo; vertebrobasilar insufficiency; transcranial Doppler, ABR.

 

Correspondence to Tarek A.Rageh, Department of Neurology and psychiatry, Assiut University Hospitals, Egypt.

Fax: +02 (088) 2333327. Email: tarek-rageh@hotmail.com.




 


INTRODUCTION

 

Vertigo entails many adverse effects on social, emotional and occupational aspects of life. In a subgroup of patients, vertigo may be a warning sign of impending vertebrobasilar stroke¹.

Vertebrobasilar insufficiency (VBI) is an important cause of vertigo because the vertebrobasilar system provide arterial blood flow to the essential structures of the vestibular system (inner ear, VIII nerve, vestibular nuclei, and their connections with folliculonodular lobes of the cerebellum)².

The classic presentation of VBI includes vertigo with head motion, dysarthria, hemiparesis, diplopia, dysphagia, ataxia and drop attacks³. However, audiovestibular symptoms can be the first and only clinical signs of VBI, and can be easily misdiagnosed as a labyrinthine disorder4.

On the other hand, dizzy patients are often falsely diagnosed as having VBI if they are within the stroke prone age group, hence misdiagnoses of cerebrovascular and inappropriate investigations are ordered and unnecessary and ineffective treatment is given5.

The principal purpose of balance function studies in patient with vertigo is localization of site of lesion. Electronystagmography (ENG) evaluates vestibular function, using electro-oculography for eye movement recording6. However, ENG do not yield diagnosis but it often detects vestibular dysfunction and help in localization of site of the lesion.

 

Abnormalities in ENG full into three categories7:

1.      Peripheral vestibular system involvement, indicate labyrinthine or vestibular nerve lesion.

2.      Central vestibular involvement.

3.      Non localizing vestibular dysfunction.

              

Auditory brainstem response (ABR) is an accurate and non invasive method for evaluation of functional integrity of the 8th cranial nerve and its connection in the brainstem.

ABR is usually normal in patients with vertigo from labyrinthine disease1. Welsh et al.8, reported that abnormal ABR pattern could assist in localizing the site of vestibular dysfunction.

Transcranial doppler (TCD) ultrasound examination of intracranial arteries is safe and reliable method for measuring relative changes in cerebral blood flow. TCD has an established position in the evaluation of flow velocities in the intracranial segments of vertebral artery (VA) and basilar artery (BA)9.

The aim of our study is to correlate between electronystagmo-graphic findings, auditory brainstem response and TCD results in patients with vertigo.

 

MATERIALS AND METHODS

 

Twenty- five patients with vertigo included in the study, in addition to 10 (age and sex matched) healthy person with no history of vertigo as a control group. The patients were selected from the outpatient clinics of neurology department and audiology unit, Assiut university hospital.

Inclusion criteria: patients with definite history of vertigo

               Exclusion criteria:  psychogenic dizziness, vertigo of established CNS focal etiology, dizziness due to metabolic or endocrinal etiology or drugs, and post–concussion vertigo.

               All subjects were submitted to full neurological, medical and audiological history and examination. Basic audiological evaluations were done included puretone audiometry, speech audiometry, tympanometry, and acoustic reflex threshold.

               Full ENG test battery was done including a search, for nystagmus both with and without fixation, with horizontal and vertical gaze deviation and with post head shaking test. Nystagmus was studied in positioning tests including Dix-Hall pike test right and left and studied in positional test including supine, head right, head left, right lateral and left lateral positions. An assessment of saccades, smooth pursuit and optokinetic nystagmus was done. Caloric function was studied with use of alternate bithermal caloric irrigation with water at 30°C and 44°C.

               ABR was performed monaurally using alternating clicks at 0.1 sec, time window was 10 mesc and filter sitting were 150Hz-3 KHz. The stimuli were delivered at 90 db with two repetition rates of 11.1 and 51.1pulses/second. Each response reflected an average of 1500 stimuli presentations. The absolute latencies of waves I, III & V and interpeak latencies of I-III, III-V &I-V of each tracing was obtained.

               TCD examination for the distal part of the VA and the proximal part of the BA was performed with 2MHz probe via the sub-occipital window. The depth of insinuation was between 60-90mm and the axis of the probe was aimed at the glabella. All examinations were made by the same investigator. This recording was matched with the subject's head in neutral position. We recorded systolic, mean flow velocity and pulsatility index from the studied arteries.

Statistical Analysis

Data are presented as mean ± SD numbers and calculation of percentage. Statistical comparison between the two groups was done using t-test, P value considered significant if ≤ 0.05. Person correlation was used to determine correlation between numeric data in each group. The chi-square test was performed to analyze the statistical association between parametric data in each group. Calculations were done with the statistical package, SPSS for window version 12.0.

 

RESULTS

 

Twenty five patients were included in this study with a mean age 49.7 years (15 female and 10 males) and 10 control  subjects (normal volunteers) age and sex matched.

The patients were divided into 2 groups: VBI group (11 patients) who had manifestation of vertebrobasilar insufficiency and non VBI group (14 patients) with no manifestation of vertebrobasilar insufficiency depending on history; neurological examination and laboratory investigations.

There was a significant difference of sex between two groups with predominance of male in VBI group and predominance of female in non VBI group (Table 1).

 

Basic audiological assessment:

Statistical analysis of pure tone audiometry thresholds showed no significant difference between both groups of patients. However, there was a highly statistical significant difference between both patients' group and control group (Table 2).

               Electronystagmography study revealed that; in VBI group nine (81.1%) patients had abnormalities in at least one of ENG tests. Positioning and positional test results were abnormal in 45.5% abnormal post head shaking in 18.2%, unilateral caloric weakness in 36.4%, and abnormal ocular motor test in 36.4% (Table 3).

In non VBI group nine (64.2%) patients had abnormalities in ENG tests. Positioning and positional tests were abnormal in 28.6% abnormal post head shaking test in 21.4%, unilateral caloric weakness in 21.4%, and abnormal ocular motor tests in 14.3% (Table 3).

 

Auditory brainstem response:

               ABR study revealed that 7 patients (63.6%) have abnormalities in one or more parameters of ABR. The mean absolute and interpeak latencies values for patients and control groups were calculated and statistically analyzed. There is no significant difference between VBI group and non VBI group in absolute and interpeak latencies of ABR. However, the VBI group showed significantly elevated mean wave V Latency and prolonged interpeak latency III-V with low and high repetition rates compared with control group. In addition they showed significantly elevated mean wave I latency and prolonged interpeak latencies I-III and I-V at higher rate (Table 4). These changes were not observed in non VBI group when compared with control group, and only two patients (14.2%) showed abnormalities in ABR parameters (Table 5).

 

Transcranial doppler study:

Transcranial doppler study   revealed a significant decrease in mean flow velocity (MFV) of right and left vertebral and basilar  arteries in VBI group compared to non VBI group. Also, there is a significant increase in pulsatility index (PI) in both vertebral arteries in VBI group compared to non VBI group (Table 6).

 

Quantitative correlations between different parameters of TCD and ABR in both study groups were done using the scatter diagram. In VBI group there were positive correlations between ABR waves III & V absolute latencies on the right side and right vertebral artery PI (Figures 1 and 2).

Also there were positive correlations between ABR wave V absolute latency & III-V interpeak latency on the left side and left vertebral artery pulsatility index (Figures 3 and 4).

In non VBI group no significant correlations were obtained between different parameters of TCD and ABR.

Qualitative correlations were done between ENG, ABR and TCD in both study groups using chi-square test.

In VBI group: results showed significant correlations between TCD & ABR and between TCD & ENG but no significant correlation was obtained between ENG & ABR (Table 7)

In non VBI group no significant correlations were obtained between TCD, ABR and ENG.


 

Table 1. Demographic and clinical data of VBI (vertebrobasilar insufficiency); versus non-VBI patients with vertigo.

Number

VBI group

 

Non VBI group

 

Control

 

11

 

14

 

10

 

Age

 

49.7±5.5

 

47.2±7. 5

 

Gender:   Male

                Female

7(63.6%)

4 (36.4%)

4 (28.5%)*

10(71.5%)*

5 (50%)

5 (50%)

 

Positional vertigo

 

5 (45.5%)

 

8(57.1%)

 

 

 

Hearing loss

 

3 (27.3%)

 

5 (35.7%)

 

 

 

Tinnitus

 

7 (63.6%)

 

8(57.1%)

 

 

 

Nausea & vomiting

 

4 (36.4%)

 

9 (64.3%)

 

 

 

Cervical radiculopathy

6 (54.5%)

 

1 (7.1%)*

 

 

 

Pyramidal  signs

 

7 (63.6%)

 

2(14.2%)*

 

 

 

* Statistically significant at p<0.05

 

 

Table 2. Pure tone audiometry among VBI (vertebrobasilar insufficiency) non-VBI patients with vertigo versus the healthy control group.

 

VBI

group

Control

P. value

Non VBI

Group

Control

P-Value

Right ear

26.96±16.77

14.2±4.6

<0.001*

30.47±20.8

14.26±4.6

<0.001*

Left ear

21.51±10.28

13.8±4.2

<0.001*

25.95±16.9

13.8±4.2

<0.001*

* Statistically significant at p<0.05

 

 

Table 3. ENG findings in VBI (vertebrobasilar insufficiency); versus non-VBI patients with vertigo.

Test

VBI (No.%)

Non VBI (No.%)

Positioning and Positional tests

5 (45.5%)

4 (28.6%)

Post head shaking test

2(18.2%)

3 (21.4%)

Unilateral caloric weakness

4 (36.4%)

3 (21.4%)

Ocular motor tests

4 (36.4%)

2(14.3%)

 

Table 4. ABR (Auditory brain stem response) parameters among VBI (vertebrobasilar insufficiency patients with vertigo versus the healthy controls.

 

Low repetition rate ABR

 

High repetition rate ABR

 

VBI

 

Control

 

P-value  value

 

VBI

 

Control

 

P-Value

 

I

1.82 ± 0.42

1.75 ±0.24

NS

1.91±0.14

1.76± 0.14

<0.05*

III

3.73 ± 0.19

3.84±0.17

NS

3.94±0.17

3.94±0.15

NS

V

5.86 ± 0.19

5.64 ± 0.28

0.04*

6.87±0.2

5.76 ± 0.17

0.0001*

I-III

2.00 ± 0.47

2.0I±0.12

NS

2.29 ± 0.25

2.08 ± 0.05

0.00*

III-V

2.12 ± 0.1

1.90± 0.22

0.04*

1.92 ± 0.31

1 .98 ± 0.08

0.05*

I-V

3.80 ± 0.58

3.77 ±0.11

NS

4.25 ± 0.32

3.95 ± 0.16

0.03*

NS non significant.

*Significant at p<0.05

 

Table 5. ABR (Auditory brain stem response) parameters among non-VBI VBI (vertebrobasilar insufficiency) versus the healthy controls.

 

Low repetition rate ABR

 

High repetition rate ABR

 

Non VBI     1

 

Control

 

P-value

 

Non VBI

Control

 

P-Value

 

I

1.77±0.1 1

1.75±0.24

NS

1.8 2±0.6

1.76±0.14

NS

III

3.8 8±0.24

3.84±0.17

 

NS

3.91±0.27

3.94±0.15

NS

V

5.72±0.42

5.64±0.28

 

NS

5.90± 0.42

5.76±0.7

NS

I-III

2.0 3±0.6

2.01±0.12

NS

2.18±0.22

2.0 8± 0.05

NS

III-V

1.92±0.34

1.90± 0.22

NS

2.10±0.41

1.9 8± 0.08

NS

I-V

3.90± 0.26

3.77±0.11

NS

4.01±0.31

3.95±0.16

NS

NS non significant

 

Table 6. Transcranially doppler findings in VBI (vertebrobasilar insufficiency); versus non-VBI patients with vertigo.

 

VBI (mean ±SD)

Non VBI (mean ± SD)

P value

VAR (MFV)

23.36 ±5.27

30.85 ±7.18

0.008*

VAL (MFV)

23.72 ±4.90

30.92 ± 6.65

0.006*

BA (MFV)

23.72 ±5.30

34.21 ±7.90

0.001*

VAR (PI)

1.01 ±0.63

0.80 ±0.1 5

0.03*S

VAL (PI)

1.03 ±0.67

0.83 ±0.1 7

0.03 1 *

BA (PI)

0.88 ±0.6

0.79 ±0.16

NS

BA basilar artery, MFV mean flow velocity, NS non significant, PI pulsatility index, VAL vertebral artery left, VAR vertebral artery right

*Statistically significant  at p<0.05

                                                                                         

Table 7. Correlations between TCD (Transcranial Doppler), ABR (auditory brain stem response) and ENG (electronystagmography) using chi-square test in VBI (vertebrobasilar insufficiency); versus non-VBI patients with vertigo.

Variables

VBI

Non VBI

X12

P value

X12

P value

TCD & ABR

1.561

0.034*

0.42

NS

TCD& ENG

1.637

0.02*

0.42

NS

ENG & ABR

0.244

NS

1.04

NS

NS non significant, X2 chi square

* Statistically significant at p<0.05

 

Figure 1. Correlation between ABR wave III right and VAR.PI.

 

 

Figure 2. Correlation between ABR wave V right and VAR.PI.

 

 

Figure 3. Correlation between ABR wave V left and VAR.PI.

 

Figure 4. Correlation between ABR IPL III-V left and VAL. PI.

 

 


DISCUSSION

 

ENG revealed abnormal findings in 81.1% of VBI group and 64.2% of non VBI group. These result agreed with Delilovic et al.10, who reported in their study that 88% of individuals in VBI group had pathological test of ENG, but in control group only 16%.

In our study unilateral caloric weakness was obtained in 36.4% in VBI group and in 21.4% in non VBI group. This agreed with results of Grad and Baloh11, they reviewed the ENG findings of patients with vertigo of cerebrovascular origin and reported that peripheral vestibular abnormalities were common on ENG testing; 42% had unilateral hypoexcitability to caloric stimulation. They suggest that the vestibular labyrinth is selectively vulnerable to ischemia within the vertebrobasilar system. In the present study we found abnormal results in other ENG tests included positioning and positional tests, post head shaking test in both VBI group and non VBI group.

Abnormal ocular motor tests were obtained in 36.4% in VBI group and in 14.3% in non VBI group. Chen and Young12 studied patients with vertigo with no conscious change or long tract signs but were diagnosed as having brainstem stroke when surveyed by magnetic resonance imaging scan. They reported that ENG revealed abnormal findings on eye tracking test, on optokinetic nystagmus test, and on caloric testing.

The study demonstrated that ENG results were abnormal in VBI group, also both peripheral and central vestibular dysfunctions were recorded with vertebrobasilar insufficiency.

ABR was abnormal in 7 out of 11(63.6%) patients with VBI, and in two patients out of 14 (14.2%) of non VBI group. This abnormality was mainly in the form of significance increase in the mean absolute latency of wave V with low and high repetition rate  compared to control group this abnormality is in  agreement with Zhang13, who found abnormal ABR results in 14 out of 24 ( 58.3%) patients  with vertigo of VBI compared to 2 out of 24 (8.3%) patients with vertigo of non VBI also Wang14 studied ABR in 93 patients with vertigo of vertebro-basilar  origin and found it abnormal in 28.3%. Wasilewska and Domzal15, described these abnormalities as affection of wave I ,III, V suggesting that disturbances of the microcirculation are responsible for the mechanism of vertigo of vertebro-basilar origin.

TCD study of vertebral and basilar arteries revealed significant decrease of the mean flow velocity in   VBI group compared to non VBI group, also study of pulsatility index   revealed significant increase in PI in VBI group compared to non VBI group. Olszewski et at16, showed significant association between velocity flow in the basilar artery after head rotation and age, prevalence of vertigo, grade of cervical radiological changes.  Baloh17 explained ischemia to be due to the anatomical contact between the vertebral arteries and the cervical spine specially in those with manifestations of atherosclerosis  and concluded that such ischemia can be often responsible for central and peripheral vestibular syndromes like vertigo, dizziness, nystagmus and disequilibrium. In a trial to correlate these abnormalities, with ABR abnormalities Zhang13 found that both TCD and ABR were abnormal in 19 out of 48 of VBI patients and he did not find such correlation in any of the 24 patients with non VBI. Li and Luo18 studied ABR and TCD in 68 patients with VBI and 30 patients with non VBI, in the VBI group ABR was affected in 84.6% while TCD in 83.1% both were abnormal in 72% of patients, while in non VBI group ABR was affected in 8.3% and TCD in 46.6% both were affected in 8.3% of patients. In our study we found a positive quantitative correlation between ABR waves III, V absolute latency on the right side  and TCD PI of the right vertebral artery whether on the left side this positive quantitative correlation was present between ABR wave V absolute latency and interpeak latency III-V, and PI of the left vertebral artery.

 

Conclusion

The cochleovestibular system disorders can be considered to be of vascular origin if patients have vascular risk factors and if other territories of brain accessible for imaging methods, show vascular disorders. So, Both TCD and ABR are complementary to each other together with ENG and  clinical evaluation in differentiating vertigo of vertebrobasilar origin versus that of non vertebro-basilar origin

 

[Disclosure: Authors report no conflict of interest]

 

REFERENCES

 

1.        Rao TH, Libman RB. When is isolated vertigo a harbinger of stroke. Ear Nose Throat J. 1995;74(1): 33-6

2.        Shepard NT, Telian SA. The neurotologic history and physical examination In: Shepard NT, Telian SA. editors.  Practical Management of the Balance Disorder patient. San Diego: Singular publishing group; 1996. p.33-50

3.        Lalwani AK.  Vertigo, disequilibrium and imbalance with aging In : Jackler R, Brackman D, editors. Neurotology. St Louis: Mosby year book ; 1994. p.527-34.

4.        Petrova D, Haning A. Electronystagmographic and caloric investigation data about vascular dysfunction among patients with vertebrobasilar insufficiency. Int Tinnitus J. 2003: 9(1): 48-51.

5.        Caplan LR. Transient vertigo, drop spells and cerebrovascular disease In: Barber IO, Sharpe JA, editors. Vestibular Disorders. Chicago: Year book Medical publishers; 1988 p.254-74.

6.        Shepard NT. Evaluation and management of balance system disorders In: Jack Katz, editor. Hand Book of clinical Audiology. New York: Williams and Wilkins; 2002. p.407-39

7.        Stock-well CW.  Vestibular function tests In: Paparella MM, Donald A, Shumrick WB, editors.  Otolaryngology. Philadelphia: Saunders; 1991. pp. 921-48

8.        Welsh LW, Welsh JI,  Rosen LG.  Evaluation of vertigo by auditory brain stem response. Ann Otol Rhinol Laryngol. 2002; 111(8): 730-5.

9.        Barber PA, Demchuk AM, Alexandrov AV. Transcranial Doppler sonography in acute stroke. J Neurol Neurosurg Psychiatry.2000; 68(4):536.

10.     Delilovic J, Demarin V, Loncarevic H,   Zarkovic   S. Correlation between transcranial Doppler sonography, Calory test of vestibularis and electronystagmography in case of vertebrobasilar insufficiency. Cerebrovasc dis. 2002; 13(4):41.

11.     Gard A, Baloh RW. Vertigo of vascular origin Clinical and electronystagmographic features in 84 cases. Arch Neurol. 1990 ; 47(1) 12-3.

12.     Chen CH, Young YH. Vestibular evoked myogenic potentials in brainstem stroke. laryngoscope. 2003; 113(6):909-3

13.     Zhang N. The correlation of auditory brainstem response and  transcranial doppler on the vertebro-basilar ischemic vertigo. Zhonghua Er Bi Yan Hou Ke Za Zhi. 1996; 31 (2): 86-8.

14.     Wang Z. Study of brain stem auditory evoked potentials in patients with vertebrobasilar blood supply insufficient. Zhoughua Shen Jing Jing Shen Ke Za Zhi. 1992; 25(1):41-63.

15.     Wasilewska H, Domzal TM.  Treatment of vertigo with betahistine and its clinical and electrophysiological evaluation, Neurol Neurochir Pol.1999; 33 (1): 63-9.

16.     Olszewski J, Majak J, Pietkiewiez P, Luszcz C, Reptowski M. The association between positional vertebral and basilar artery flow lesion and prevalence of vertigo in patients with cervical spondylosis. Otol Head Neck Surgery. 2006; 34: 680-4

17.     Baloh RW.  Vertebrobasilar insufficiency and stroke. Otol Head Neck Surgery.1995 2:114-7

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الملخص العربى

 

دور الجهد المستثار السمعى ودراسة رقرقة العين والأشعة بالدوبلر عبر الجمجمة فى تقييم مرضى الدوار

 

            أجريت هذه الدراسة بغرض استبيان دور الجهد المستثار السمعى ودراسة رقرقة العين والأشعة بالدوبلر عبر الجمجمة فى تقييم مرضى الدوار الناتج عن قصور فى الشرايين الفقرية والشريان القاعدى ومقارنتها بالدوار الناتج عن اسباب اخرى (طرفية).

            وقد أجريت هذه الدراسة على 25 مريض تتراوح أعمارهم بين 40 إلى 60 عام يعانون من الدوار مع عينة ضابطة تتكون من 10 متطوعين. وقد خضع المرضى لتقييم إكلينيكى للجهاز العصبى والجهاز السمعى بصورة دقيقة مع دراسة الجهد المستثار السمعى ودراسة رقرقة العين والأشعة بالدوبلر عبر الجمجمة. وقد تم تقسيم المرضى إلى مجموعتين: مجموعة (1) وتشمل 11 مريض يعانون من دوار ناتج عن قصور فى الدورة الدموية للشرايين الفقرية ومجموعة (2) وتشمل 14 مريض يعانون من الدوار لأسباب أخرى (طرفية).

            وقد اظهرت الدراسة أن مرضى المجموعة (1) يعانون بأختلال فى دراسة رقرقة العين بنسبة 81.8% وإعتلال فى نتائج الأشعة بالدوبلر على شرايين المخ بنسبة 72.7% وكذا تأثر سلبى فى دراسة الجهد المستثار السمعى بنسبة 63.6%. أما المجموعة (2) فقد اظهرت النتائج نسب الإختلال فى وظائف رقرقة العين والأشعة بالدوبلر على شرايين المخ ووظائف الجهد المستثار السمعى 64.2% ، 21.4% ، 14.2% على التوالى.

كما أظهرت النتائج وجود ارتباط إيجابى ذو دلالة إحصائية ما بين تأخر الموجة الثالثة والخامسة للجهد المستثار السمعى ومعامل الإنقباض للشرايين الفقرية.

ومما سبق نستنتج أن دراسة الدوبلر على الشرايين المخية عبر الجمجمة مرتبطاً بالدراسات الأخرى (الجهد المستثار السمعى ودراسة رقرقة العين) ذو قيمة فى التشخيص المبكر للمرضى الذين يعانون من قصور الشرايين الفقرية فى مرضى الدوار.



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