Vertebro-basilar insufficiency (VBI) is a brief episode of reversible neurological deficits caused by transient ischemia of the brainstem due to impairment of the vertebro-basilar arterial system.
VBI was introduced initially as “syndrome of intermittent insufficiency of vertebro-basilar arterial system” and its pathophysiology was recognized to be vascular dysfunction of the brainstem in the early 20th century. Later, in the 1950's, VBI was proposed to be one clinical entity characterized by various combinations of recurring neurologic symptoms and signs involving vertigo, disequilibrium, double vision, visual hallucination, gait ataxia, face and limb numbness, weakness, dysarthria and dysphagia. The common causes of VBI were considered as atherosclerosis, which can block the posterior circulation supplying the brainstem, embolism arising from the heart and the proximal vertebral and basilar arteries due to arrhythmia, and hemodynamic disorder related to changes of the blood pressure, as well as mechanical obstruction of the vertebral artery induced by vertebral spicules.
Various modalities such as vertebral angiography, Doppler ultrasonography, MRI and MRA are now available as useful tools for identifying the vascular structural lesions. Diffusion-weighted MRI may be useful to identify early ischemic lesions. However, it remained no major changed fundamentally in the present for diagnosis techniques depending on the history of the attacks, because it is still difficult to clinically determine the precise circulation disorder within the vertebro-basilar arterial system. Further discussions are needed to consolidate the diagnostic criteria, including the concept and pathogenesis of VBI with vertigo, in the future.
A major purpose of aeromedicine as a specialty is the prevention of aircraft accidents. Only prevention can save lives. From the earliest days of aviation, almost all aviation accidents have been attributed to the human factor called spatial disorientation. To understand spatial disorientation, one must comprehend how the human body interacts and interprets the environment of flight. This understanding can help to provide control and prevent loss of spatial orientation that can lead to aviation accidents.
Ocular tilt reaction (OTR) is the roll-plane manifestation of a vestibular tone imbalance, characterized by ocular torsion, skew deviation, and tilts of the subjective visual vertical (SVV) with/without head tilts. The OTR can result from any unilateral lesion of the graviceptive pathways from the labyrinth to the contralateral interstitial nucleus of Cajal in the rostral midbrain via the medial longitudinal fasciculus. All tilt effects are ipsiversive, with a unilateral lesion below the crossing of the graviceptive pathways. All tilt effects are contraversive, with a unilateral pontomesencephalic lesion. The OTR may only induce vertical diplopia subjectively. While vertical diplopia from the OTR is well-known in brainstem lesions, the peripheral OTR is rare and fleeting and usually seen after acute vestibular deafferentation. By contrast, the OTR in our case with a vestibular schwannoma suggests a chronic peripheral form. Despite complete left canal paresis in our case, dizziness or imbalance had become unrecognizable, masked by central vestibular compensation. Consistently, along with the tumor growth, the patient's OTR improved, possibly through central adaptation promoted by further utricular damage in the vestibulocochlear nerve. Through a literature survey, we wish to make at least three statements regarding the peripheral OTR: 1) overt OTR is infrequent or may have escaped recognition in the acute phase of vestibulopathy because of vertigo/nystagmus and neurovegitative symptoms; 2) the causal relationship between ocular torsion and SVV tilts has yet to be resolved, and 3) ocular torsion may be conjugate or disconjugate with the larger extorsion of the ipsilateral eye.
It is valuable for clinicians to have a measure of the dizziness handicap of pediatric patients.
However, children are not yet sufficiently mature to express their dizziness exactly. Parents, who spend much time with their children, are an excellent source of information about their children's problem. The Dizziness Handicap Inventory for Patient Caregivers (DHI-PC) is a questionnaire in which a parent answers questions that are posed to evaluate the degrees of handicap in the daily lives of pediatric patients with dizziness on a scale, with a “No”, “Sometimes”, or “Yes”. The target age of the subjects for the original version of DHI-PC is under 13 years old. The reliability of the Japanese version of the DHI-PC (DHI-PC-J) has been reported in 2018. The aim of the present study was to examine whether the target age can be extended to 17 years old. The DHI-PC-J was administered to 40 caregivers of pediatric patients between the ages of 5-17 years old. The subjects were classified into two groups according to their age: ≤12 years old and ≥13 years old. The DHI-PC-J scores showed significant correlations with the Visual Analogue Scale (VAS) score of dizziness handicap in each age group. This result indicates that the DHI-PC-J is a reliable questionnaire that can be used to assess the degree of handicap in the daily lives of pediatric patients under 18 years old with dizziness in Japan.
We occasionally encounter patients with refractory endolymphatic hydrops, including Ménière's disease, who manifest recurrent attacks of vertigo despite medical treatment. The guideline for the treatment of Ménière's disease recommends transtympanic positive-pressure therapy for refractory cases with failure of conservative therapy, before surgery is considered. Overseas, micropressure treatment using the Meniett® low-pressure pulse generator has been reported to be effective for reducing the symptoms of this disease. On the other hand, the tympanic membrane massage device (hereinafter referred to as the non-invasive pressure pulse generator) has been used for patients with otitis media with effusion. Unlike the Meniett® device, it can deliver intermittent pressure to the middle ear without tympanostomy tube insertion and is associated with fewer adverse events. Multicenter studies have been carried out in Japan to determine whether the non-invasive pressure pulse generator is of therapeutic benefit against Ménière's disease.
The present study was focused on the efficacy of the non-invasive pressure pulse generator for refractory Ménière's disease.
A total of 19 adults with Ménière's disease were included in the study. Treatment with the non-invasive pressure pulse generator was self-administered 3 times daily for 4 months.
The patients reported a significant decrease in the number of vertigo attacks after the first month of treatment. Of the total, 64% reported a significant reduction in the number of vertigo attacks for 12 months after the treatment.
Our results suggest that transtympanic positive-pressure therapy using a non-invasive pressure pulse generator is effective for alleviating the symptoms of Ménière's disease.
The purpose of vestibular function testing is to objectively evaluate the patient's subjective imbalance, record measurements, topically diagnose balance disorders, and estimate the effects of treatment. The caloric response was first described by Robert Barany in 1906. His findings were immediately considered pivotal recognized and he received the Nobel Prize. The key observation for which he was awarded the Nobel Prize was made while he was irrigating out ear wax in a patient after, when? the patient complained that the water was the wrong temperature. Barany noticed that the eyes moved in different directions with the use of warm- and cold-water irrigation. This demonstrates the value of being observant.
This test assesses the degree to which the vestibular system is responsive, and how symmetric the responses are responsiveness of the vestibular system and the symmetry of responses between the left and right ears. Only the lateral semicircular canals are evaluated, and not the vertical canal or functions of the otolith. Although it is not perfect, the caloric test is the best available method to deduce the function of each ear independently.
The caloric test has been used worldwide for many years as a de-facto standard to evaluate the function of the lateral semicircular canal, together with the rotational stimulus test. This report describes the past and future of the caloric test.
The head impulse test (HIT), which was first introduced by Halmagyi and Curthoys in 1988, is a clinical test to assess the vestibular function by brisk, passive rotation of the head in the plane of the parallel semicircular canal pairs. In healthy subjects, the vestibulo-ocular reflex (VOR) stabilizes the gaze in space by inducing equal eye rotation in the opposite direction to compensate for the head rotations. On the other hand, in patients with vestibular dysfunction, the eyes move with the head because of insufficient VOR leading to catch-up saccade movements in order to re-fixate on the target. It had been difficult to quantify HIT since a scleral search coil system, which is an expensive, complicated and semi-invasive technique, was necessary to record the HIT. However, a simple video recording method of HIT (vHIT), was introduced by McDougall et al. in 2009, and is now used by many clinics around the world. In this article, I describe 1) the physiological basis of HIT, 2) the method of recording vHIT, 3) the usefulness of vHIT in clinical practice, and 3) the pitfalls in recording and interpreting vHIT.
VEMP (vestibular evoked myogenic potential) is an electromyographic response elicited from the vestibular labyrinth by sound, vibration, or electrical stimulation. VEMP is a clinical test for the otolith organs, sensors of linear acceleration and related reflex pathways. Two types of VEMP, cervical VEMP (cVEMP) and ocular VEMP (oVEMP), have been applied clinically. In this short review, the author shows the neurophysiological bases of the VEMPs, the recording methods, and the methods of interpretation of the data obtained. Furthermore, the author discusses the possible diagnostic merits of combined use of VEMPs and vHIT (video head-impulse test) in the near future.
A small maintained sustained electrical current passed between electrodes on the skin over each mastoid (galvanic vestibular stimulation: GVS) activates the vestibular system and elicits vestibular responses, such as the sensations of rotation, eye movements and postural instability. The GVS test is increasingly being used to test vestibular functions, as it can be used to test both human and animal vestibular systems. It modulates the vestibular signal by increasing the firing rate of afferents on the cathodal side and decreasing the firing rate on the anodal side, causing standing subjects to sway towards the anodal side. Galvanic body sway test (GBST) provides important information for differential diagnosis between inner ear and retro-labyrinthine disorders of the vestibular system. On the other hand, interpretation of nystagmus is difficult, because precise measurement of the eye movements by electronystagmography is not feasible. However, with the development of video-oculography (VOG), it has recently become possible to carry out accurate recording and evaluation of nystagmus.
Recent technological developments, including the use of improved VOG, might lead to the rediscovery of GVS as a research and diagnostic tool.