VEMP (vestibular evoked myogenic potential) is an electromyographic response originating from the vestibular labyrinth, especially the otolith organ, evoked by sound, vibration, or electrical stimulation. Two types of VEMP, cervical VEMP (cVEMP) and ocular VEMP (oVEMP) have been assessed clinically. In this short review, the author briefly describes the history, basic neurophysiological findings, recording methods, and data interpretation in VEMP testing. Furthermore, the author also discusses the expectations for possible clinical applications of VEMP testing in the near future.
Persistent postural-perceptual dizziness (PPPD) is a newly defined diagnostic syndrome that was included in the 11th edition of the World Health Organization's International Classification of Diseases (ICD-11) in 2018. PPPD is characterized by persistent chronic vestibular syndrome, typically preceded by acute vestibular disorders, lasting for >3 months. The core vestibular symptoms of PPPD are dizziness, unsteadiness, and/or non-spinning vertigo and are exacerbated by upright posture/walking, active or passive movements, and exposure to moving or complex visual stimuli. PPPD is classified as a functional disorder, and not as a structural or psychiatric condition. No specific laboratory tests for the diagnosis of PPPD are available, and an assessment of the symptoms, exacerbating factors, and medical history is important for the precise diagnosis of PPPD. Although the exact pathophysiology of PPPD remains to be elucidated, data from physiological investigations and rapidly emerging advanced structural and functional neuroimaging studies have revealed some key mechanisms underlying the development of this disorder, including stiffened postural control, a shift in processing spatial orientation information to favor visual or somatosensory over vestibular inputs, and failure of higher cortical mechanisms to modulate the first two processes. Although PPPD is a relatively new diagnosis and will therefore be unfamiliar to many health professionals, undiagnosed or untreated dizzy patients who have been suffering for many years can be saved. Once recognized, PPPD can be managed by effective communication and individually tailored treatment strategies, including serotonergic medications, vestibular rehabilitation and cognitive behavioral therapy.
It is known that a certain percentage of cases among vertigo patients with apparent peripheral disturbances actually suffer from central vertigo. Especially, vertigo caused by infarction of the posterior inferior cerebellar artery (PICA) territory may sometimes be difficult to diagnose because of the lack of central neurological signs. We encountered a patient with infarction of the area supplied by the PICA who was diagnosed by CT as having peripheral vertigo , but was then eventually definitively diagnosed as a case of infarction of the PICA territory by MRI.
In addition to this case report, we conducted a study to determine the key words that led to a request for an MRI to diagnose central vertigo, especially infarction of the PICA territory. We extracted key words relating to these cases from a review of the literature published over the last 25 years; the search identified irregular nystagmus, vomit, stroke risk factors like hypertension, hyperlipidemia, diabetes mellitus and atrium fibrillation, senior citizens, and posterior neck pain as important key words for recommending an MRI for confirming the suspected diagnosis of PICA-territory infarction.
We collected data from the Foulage test performed using the six-axis motion sensor, an accelerometric device, in 6 healthy adults (all men aged 27.32±5.89). The Foulage test was performed with the six-axis motion sensor in placed on the lumbar spine of the subjects, and the data were analyzed and correlations examined. The root mean square (RMS), auto-correlation coefficient (AC) and Euler horn were calculated from the data provided by the six-axis motion sensor. The FT value and Θ value were calculated from Foulage test. There were significant correlations between the AC x-axis of the linear/angular acceleration and the FT value. There were also significant correlations between the Euler horn y-axis and Θ value. Our results suggested that the “x-axis at the lumbar spine level” affected the Foulage stepping. This accelerometric device is easy to use and requires no specialized equipment and can be used to perform the Foulage test in clinical practice.
A cognitive function test was performed on 220 elderly people who presented with the chief complaint of dizziness. The examination by the Imon Cognitive Impairment Screening Test (ICIS) was conducted by nurses in a face-to-face manner. The proportion of subjects with normal cognitive function decreased with age. The percentage of subjects under 75 years of age with normal cognition was lower among elderly subjects with dizziness than in the general Japanese elderly people. The presence of central abnormalities in the balance function tests was associated with deterioration of cognitive function. However, in subjects under the age of 75 years, there was no relationship between the central findings and cognitive function. No correlation was observed between orthostatic hypotension and cognitive function. No relationship of the cognitive function with anxiety, depression or DHI was observed either. Two patients were diagnosed as having Alzheimer's disease at the Department of Neurology and one patient was diagnosed as having Lewy-body dementia due to abnormalities in the ICIS. Existence of a relationship between vestibular dysfunction and cognitive dysfunction has been reported, and it is important to perform cognitive screening in otolaryngology outpatients. It is necessary to consider intervention in dizzy patients under 75 years of age who are suspected as having MCI.