Research in Vestibular Science

Reviews

Clinical Application of the Head Impulse Test in Vestibular Disorders: Seung Han Lee; Res Vestib Sci. 2015;14(1):1-8.

Abstract PDF: The head impulse test (HIT) is an established way to test the angular vestibulo-ocular reflex (aVOR) at the bedside. When the aVOR is normal, the eyes rotate opposite to the head movement through the angle required to keep images stable on the fovea. If the aVOR is impaired, the eyes move less than required and, at the end of the head rotation, the eyes are not directed at the intended target and the visual image is displaced from the fovea. A promptly-generated corrective saccade brings the image of the target back on the fovea. The identification of this corrective saccade is the signature feature of vestibular hypofunction and has greatly increased the utility of the bedside examination for identifying an aVOR deficit. However, sometimes it is not easy to detect corrective saccades without quantitative HIT devices. Exact execution and interpretation of the HIT are warranted to reduce the diagnostic errors, because the HIT has become an important part of the differential diagnosis of both acute and chronic vestibular disturbances.

The Principle and Methodology of Vestibular Evoked Myogenic Potential: Min Young Lee, Myung Whan Suh; Res Vestib Sci. 2015;14(1):9-14.

Abstract PDF: Vestibular evoked myogenic potential (VEMP) has developed as a broadly applied vestibular function test in clinics from its introduction in 1992. In the past, there was only one well known VEMP protocol, which is cervical VEMP, however recently ocular VEMP is also popular. Therefore, clarifying the VEMP recording protocol (cervical VEMP or ocular VEMP) before discussing the VEMP
result
has become essential. There is considerable difference regarding this VEMP test from other vestibular function tests. VEMP is thought to be assessing the functions of the otolith organs (utricle and saccule) which are evoked by acoustic stimulus. Cervical VEMP is valuable since this is the only available test method which could speculate the function of the saccule and inferior vestibular nerve. Still, there’s less clearly understood part regarding the central pathway of VEMP. However, many clinicians and researchers participating in vestibular research speculate that this functional test will have a more dominant role in the near future. Here we describe the basic principles and methodological considerations regarding VEMP recording.

Original Article

Otolith Function Tests in Patients with Orthostatic Dizziness: Su Hyun Ahn, Eun Ju Jeon, Yong Soo Park, Dong Hyun Kim, Inn Chul Nam; Res Vestib Sci. 2015;14(1):15-20.

Abstract PDF: Background
and Objectives: Orthostatic dizziness (OD) is defined as when dizziness is provoked by standing up from a supine or sitting position. It is usually considered as being associated with orthostatic hypotension (OH). On the other hand, it is recently suggested that otolith organ dysfunction and impaired vestibulosympathetic reflex may account for development of OH and OD. Vestibular evoked myogenic potential (VEMP) and subjective visual vertical and horizontal tests (SVV/SVH) are tools for detecting otolith organ dysfunction. We assessed cervical VEMP (cVEMP) and SVV/SVH test results in the patients with OD to evaluate the relationship between OD and otolith organ function. Materials and Methods: Three hundred-eighty-seven patients who visited dizziness clinic were enrolled in this study. Seventy-three patients presented with OD (i.e., group O), while 314 patients did not present OD (i.e., group N). Vestibular function tests including cVEMP and SVV/SVH were performed. Results: cVEMP showed abnormal response in 47.9% of group O and 60.2% of group N. Abnormal SVV was found in 35.6% of group O and 31.5% of group N. Abnormal SVH was highly found in both group O and group N (30.1%, 27.1%). Conclusion: The values of SVV/SVH and cVEMP abnormality from both groups were not significantly different between the groups O and N. This finding suggests that otolithic function may not be related with OD.

Case Reports

Vestibular Dysfunction in Acute Cerebellar Ataxia: Chang Min Lee; Res Vestib Sci. 2015;14(1):21-25.

Abstract PDF: Acute cerebellar ataxia is described as a clinical syndrome of acute onset of cerebellar dysfunction with a good long-term prognosis. The pathogenesis of acute cerebellar ataxia remains unclear. A 55-year-old woman presented with acute onset of gait ataxia and dysarthria. The videonystagmography showed saccadic pursuit and saccadic abnormalities including slightly prolonged latency and hypometria. Rotational chair test revealed increased vestibuloocular reflex (VOR) gains and a failure of VOR suppression by visual fixation. Brain magnetic resonance imaging and cerebrospinal fluid examination were normal. The patient was treated with steroids and made nearly complete recovery over a period of 3 months.

Two Cases of Barotraumatic Perilymph Fistula Mimicking Atypical Benign Paroxysmal Positional Vertigo with Sudden Hearing Loss: Jung Joo Lee, Gwanghui Ryu, Il Joon Moon, Won Ho Chung; Res Vestib Sci. 2015;14(1):26-31.

Abstract PDF: Barotraumatic perilymph fistula is difficult to diagnose and needs diagnosis of suspicion. Symptoms like hearing loss, tinnitus, ear fullness and positional dizziness can develop following barotrauma such as valsalva, nose blowing, straining and diving, etc. We reported 2 cases of perilymph fistula following barotrauma. The patients developed hearing loss, tinnitus and ear fullness followed by sudden onset of positional dizziness mimicking benign paroxysmal positional vertigo (BPPV). On positional tests, the direction of nystagmus has changed over time. In addition, the characteristics of nystagmus on positional test were not similar to typical BPPV, which showed longer duration of nystagmus, no reversibility and no fatigability. We concluded that barotraumatic perilymph fistula could present as hearing loss with positional dizziness mimicking sudden hearing loss with BPPV. The differential diagnostic points were history of barotrauma, time sequence of development of hearing loss and positional dizziness, and atypical positional nystagmus unlike BPPV.

Tumarkin Otolithic Crisis Controlled by Endolymphatic Sac Surgery: Seok Min Hong, Il Seok Park, Jae Ho Ban; Res Vestib Sci. 2015;14(1):32-35.

Abstract PDF: Turmarkin otolithic crisis is a rare feature of Meniere’s disease. It shows sudden falling to the ground with no warning sign. It is an otologic emergency because of the risk of falling, and it has traditionally been treated with labyrinthectomy or vestibular neurectomy. We experienced a 49-year-old male suffering from recurrent drop attack, and found that he had hearing loss, tinnitus or recurrent vertigo on his left ear, and could make a diagnosis him as Tumarkin otolithic crisis. We have performed the endolymphatic sac decompression, considering the hearing preservation and therapeutic opinion of patients. Two years after surgery, he showed intermittent, mild dizzy symptoms, without further drop attack. Therefore, we report our clinical experience with a brief review of literature.

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