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Case Report Korean J Otorhinolaryngol-Head Neck Surg 2014;57(8):552-5 / pISSN 2092-5859 / eISSN 2092-6529

http://dx.doi.org/10.3342/kjorl-hns.2014.57.8.552

Introduction

Acute vestibular neuritis (VN) without neurological symp-toms or signs is one of the most common acute peripheral ves-tibulopathies (APV), which is characterized by acute onset of long-lasting (several days) vertigo, spontaneous unilateral hor-izontal and torsional nystagmus toward the contralesional side, and ipsilesional canal paresis to caloric stimulation.1) How-ever, central pathologic conditions may also present with symp-toms or signs that mimic vestibular neuritis, which have been called pseudo-VN.2)

Although an extensive retrospective cohort study has re-ported that less than 1% of patients with acute isolated verti-go have a central pathology, delayed or missed diagnosis of infarction may result in critical morbidity and mortality.3) There-fore, some authors suggested that among the cerebellar infarc-

tion patients with fixed and persistent spontaneous nystagmus, 1) older patients, 2) any patient with vascular risk factors show-ing negative head thrust test, and 3) patients showing direc-tion-changing gaze-evoked nystagmus or severe ataxia can be suspected for pseudo-VN and hence require brain magnetic resonance image (MRI).2)

Here we report a case of a young patient free of vascular risk factors, who developed cerebellar infarction with contralesion-al canal paresis possibly due to an embolism from bilateral vertebral artery dissection (VAD).

Case

A 39-year-old female patient without any stroke risk factors was hospitalized after an acute onset of severe vertigo, nausea, and vomiting. The patient only complained of vomiting and diz-

A Case of Pseudo-Vestibular Neuritis with Contralesional Canal Paresis due to Spontaneous Bilateral Vertebral Artery Dissection

Dae Bo Shim, Mee Hyun Song, Kye Chun Park, and Chang Eun SongDepartment of Otorhinolaryngology, Myongji Hospital, Goyang, Korea

양측 자연적 척추동맥박리에 의해 발생한 반대측 반고리관마비를 동반한 가성 전정신경염

심대보 ·송미현 ·박계천 ·송창은

명지병원 이비인후과

Received December 6, 2013Revised January 22, 2014Accepted February 4, 2014Address for correspondenceChang Eun Song, MDDepartment of Otorhinolaryngology, Myongji Hospital, 55 Hwasu-ro 14beon-gil, Deogyang-gu, Goyang 412-270, KoreaTel +82-31-810-5445Fax +82-31-810-6357E-mail entsong@gmail.com

Pseudo-vestibular neuritis is a central pathology of acute vestibular syndrome, characterized by unidirectional nystagmus mimicking acute peripheral vestibulophaty. We report a 39-year-old female patient who developed cerebellar infarction with isolated vertigo, spontaneous nystag-mus, a positive head thrust test, and unilateral canal paresis in the contralesional side. The pa-tient had no vascular risk factors. A diffusion-weighted image of the brain showed infarction of medial branch of posterior inferior and superior cerebellar artery on the left side. A magnetic resonance angiography of neck disclosed a wide range of diffused severe stenosis and narrow-ing of right and left vertebral arteries, respectively. This case suggests the possibility of vestib-ular ischemia masking the central pathology in isolated vertigo. Korean J Otorhinolaryngol-Head Neck Surg 2014;57(8):552-5

Key WordsZZEmbolism ㆍVertebral artery dissection ㆍVestibular neuritis.

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ziness without any complaint of headache, neck pain, or hear-ing impairment. The patient had no previous known stroke risk factors such as hypertension, diabetes mellitus, smoking his-tory or prior stroke. Examination of the cranial nerve function including pupillary reflex revealed normal. The motor and sense of the extremities were normal. Due to severe dizziness and fatigue, righting reflex could not be tested but cerebellar function test did not reveal any typical abnormal findings such as dysmetria. Videonystagmography (VNG) showed left-beat-ing horizontal nystagmus with torsional component compli-ant with the Alexander’s law. After head shaking, the degree of left-beating nystagmus was augmented. Head thrust test (HTT) revealed a corrective saccade typically seen in acute VN. Subjective visual vertical (SVV) test with binocular view-ing showed 6.0 degree tilt toward the right side (normal range in our institute: -2.0 to 2.3 degree). The patient strongly re-fused hospitalization because she thought that she would not be able to breastfeed her newborn baby in the proper atmo-sphere. When the VNG test was repeated before discharge from the emergency unit, a direction-changing gaze evoked nystagmus (GEN) was recorded. In order to rule out any cen-tral pathology, a diffusion brain MRI was performed. MRI demonstrated acute cerebellar infarction that involved the ter-ritory of the medial branch of posterior inferior cerebellar ar-tery (mPICA) and superior cerebellar artery (SCA) on the left side (Fig. 1). The patient was then admitted to the department of neurology after which anticoagulant therapy was instituted.

On the first day of admission, neck MRA showed wide range of diffuse severe stenosis of the right vertebral artery (VA) sparing only the V4 segment. Left VA revealed narrowing of the V2 segment and dissecting aneurysm (Fig. 2). On the fourth day of admission, transfemoral cerebral angiography

was performed, which demonstrated complete reperfusion of both VAs together with wide range of luminal irregularity of both VAs and dissecting aneurysm of the left VA (Fig. 3). Ver-tigo disappeared completely by the third day of hospitalization, and abnormal nystagmus was absent on follow-up VNG test-ing except for a positive HTT. SVV tilt of the patient was nor-malized (0.1° tilt toward right side). Refixation saccade dur-ing HTT disappeared on the fourth day of hospitalization. On the vestibular function tests performed four days after hospi-talization, bithermal caloric test revealed a 68.3% decrease in caloric response on the right side, while vestibular evoked myo-genic potential test was normal. The result of pure-tone audio-

Fig. 1. Brain diffusion weighted im-aging shows multifocal acute infarc-tion of the left cerebellar hemisphere in the territory of the superior cerebel-lar artery (white arrow in A) and the medial branch of posterior inferior ce-rebellar artery (white arrow in B).

A B

Fig. 2. Neck magnetic resonance angiography shows diffuse se-vere narrowing of V2 segment (white arrowheads) and a small fu-siform dissecting aneurysm (white arrow) of left vertebral artery, and no visualization of right vertebral artery (open arrowheads) except for the V4 segment (open arrow).

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gram was unremarkable. On day 5, the patient was discharged relieved of all symptoms.

Discussion

Approximately 11% of patients with isolated cerebellar in-farction have shown vertigo as an isolated symptom, and most (96%) of them had infarction in the territory of mPICA.2) The nodulus, which is supplied by mPICA, is a critical structure in determining the direction specific pattern of otolith dysfunc-tion and in eliciting cerebello-vestibular connections by the inhibitory nodulovestibular Purkinje fibers in PICA territory cerebellar infarction.2,4) When it is involved pathologically, the patient presents with contraversive tilts of SVV, ocular torsion, and skew deviation as well as spontaneous unidirectional nys-tagmus; therefore, patients with mPICA territory cerebellar infarction may sometimes be misdiagnosed with acute VN.2,4) On the other hand, since the superior cerebellum supplied by the SCA does not have significant vestibular connections, cer-

ebellar infarction in the SCA rarely causes vertigo. Prominent body lateropulsion in isolated medial SCA territory cerebel-lar infarction may be explained by involvement of rostral ver-mis that is related predominantly to gait, muscle tone, and pos-tural control.5)

The exact pathomechanism of VAD is unknown. The hem-orrhage that occurs in arterial dissection usually involves an intimal tear or bleeding of the vasa vasorum that gives rise to blood extending into the medial layer. This can eventually lead to narrowing of the vessel lumen with resultant partial or com-plete obstruction. Thrombotic or embolic complications may follow.6) Some authors have suggested that an artery-to-artery embolism may result in labyrinthine artery infarction giving rise to vertigo and hearing loss.7) The embolism in vertebro-basilar system may cause various symptoms, such as isolated vertigo, isolated deafness, or vertigo and deafness, depending on the branches involved.7)

Our case demonstrated cerebellar infarction involving mul-tiple vascular territories including mPICA and SCA on the left side caused by spontaneous bilateral VAD that presented with unusual findings such as a contralateral canal paresis and con-traversive SVV tilt, and a positive HTT lasting for 3 hospital days. Although our patient’s VNG results were compatible with the previously explained pathomechanism of pseudo-VN, the findings such as canal paresis and positive HTT of our patient are far from the typical findings of left cerebellar infarction. When the unilateral cerebellum (including nodu-lus) is damaged, SVV angle tilts to the contralesional side. There-fore, the authors speculate that the hypoperfusion of the con-tralesional anterior vestibular artery, which supplies the utricle, superior part of saccule and ampulae of the anterior and hori-zontal semicircular canals, may have resulted in vestibular ischemia causing the contralesional canal paresis and contra-versive tilt of SVV as well as positive finding of HTT since the lesion did not involve the nodulus or the uvula in the pres-ent case.

Central pathology cannot be ruled out merely with an iso-lated sign or through simple physical examination in the diag-nosis of APV. Nevertheless, HTT is the single most valuable diagnostic test in distinguish APV from stroke in patients with isolated vertigo. A recent study reported that three oculomo-tor assessments (including HTT, redirective GEN by eccen-tric gaze, and skew deviation) can potentially achieve 100% sensitivity and 96% specificity in differentiating acute dizzi-ness caused by an infarction.8)

Because our patient showed typical nystagmus of APV (uni-

Fig. 3. Transfemoral cerebral angiography performed 4 days after the onset of vertigo. Although there was spontaneous recanaliza-tion of the right vertebral artery occlusion that was identified on pre-vious neck magnetic resonance angiography, diffuse luminal irreg-ularity (open arrowheads in A) was identified. Diffuse luminal irregu-larity (white arrowheads in B) and a small dissecting pseudoaneu-rysm (white arrow in B) were identified in the left V2 segment.

A B

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directional spontaneous nystagmus consistent with the Alex-ander’s law and a positive HTT) in the initial physical exami-nation, a central pathology was masked in differentiating from APV. If the redirective GEN had not been observed on the fol-low-up VNG test, the patient might have suffered catastroph-ic complications. Indeed, HTT and GEN do require skillful-ness and experience for proper interpretation and the results are potentially subject to examiner bias.

In this case, a young patient who developed pseudo-VN was comorbid with vestibular infarction from spontaneous bilat-eral VAD. This suggests that the contralesional vascular isch-emia from bilateral VAD may cause vestibule-ocular reflex impairment masking a central pathology. We suggest that phy-sicians should pay careful attention to other subtle findings, such as GEN or skew deviation, even if HTT shows positive result in patients with isolated vertigo.

REFERENCES1) Strupp M, Brandt T. Vestibular neuritis. Adv Otorhinolaryngol 1999;

55:111-36.2) Lee H, Sohn SI, Cho YW, Lee SR, Ahn BH, Park BR, et al. Cerebellar

infarction presenting isolated vertigo: frequency and vascular topographical patterns. Neurology 2006;67(7):1178-83.

3) Kerber KA, Brown DL, Lisabeth LD, Smith MA, Morgenstern LB. Stroke among patients with dizziness, vertigo, and imbalance in the emergency department: a population-based study. Stroke 2006;37 (10):2484-7.

4) Kim HA, Lee H, Yi HA, Lee SR, Lee SY, Baloh RW. Pattern of otolith dysfunction in posterior inferior cerebellar artery territory cerebellar infarction. J Neurol Sci 2009;280(1-2):65-70.

5) Nitschke MF, Kleinschmidt A, Wessel K, Frahm J. Somatotopic motor representation in the human anterior cerebellum. A high-resolution functional MRI study. Brain 1996;119(Pt 3):1023-9.

6) Choi KD, Chun JU, Han MG, Park SH, Kim JS. Embolic internal auditory artery infarction from vertebral artery dissection. J Neurol Sci 2006;246(1-2):169-72.

7) Kim SH, Kosnik E, Madden C, Rusin J, Wack D, Bartkowski H. Cerebellar infarction from a traumatic vertebral artery dissection in a child. Pediatr Neurosurg 1997;27(2):71-7.

8) Kattah JC, Talkad AV, Wang DZ, Hsieh YH, Newman-Toker DE. HINTS to diagnose stroke in the acute vestibular syndrome: three-step bedside oculomotor examination more sensitive than early MRI diffusion-weighted imaging. Stroke 2009;40(11):3504-10.