Although the basis for both the sporadic and inherited forms of Meniere's disease (MD) remain undefined, it is likely to be multifactorial, one of the factors being a genetic predisposition. Several candidate genes, such as AQPs, COCH, and HLA, have been proposed for MD, many of them regulating directly or indirectly the ionic or water transport of the inner ear. Mutations/polymorphisms in KCNE potassium channel genes might play a causative role in MD, because KCNE potassium channels have been suggested to be involved in the transmembrane ion and water transport mechanisms of the inner ear. The SNPs analyses identified that 112G/A SNP in the KCNE1 gene and 198T/C SNP in the KCNE3 gene could determine an increased susceptibility to develop MD. Because of the familial clustering, the geographical and racial differences, no convincing evidence for an association with any genes in the development of MD exists. The phenotypic diversity of MD makes the selection of patients a challenge, and the late onset of the disease may complicate the selection of the controls. Finally, the predisposing factors for MD should differ between ethnic groups and even between families affected. In summary, existing candidate gene reports provide very little information on the etiology of MD at present. Future studies should emphasize the need to collect larger, well-defined control groups as well as sporadic/familial MD patients.
Autoimmune inner ear disease (AIED) was reported by McCabe in 1979 and was characterized by episodic vertigo and fluctuating hearing loss. Some patients develop total deafness and severe disequilibrium which disturbs their activities of daily living (ADL). Steroids or immune suppressing agents are used to control symptoms, but they have to be given repeatedly, because the symptoms tend to recur. We analyzed 22 AIED patients diagnosed by the presence of a 68kDa protein. The patients with low grade hearing loss showed some recovery of their hearing, However, hearing recovery was not noted in any patient with severe hearing loss. It is important to diagnose AIED and start treatment as soon as possible.
Bow-tie nystagmus is a rare phenomenon, which is reportedly associated with cerebellar infarction, brain stem anomalies, and so on. We analyzed herein bow-tie nystagmus in a patient with an Arnold-Chiari malformation using a three-dimensional 240 Hz high speed video oculography (VOG) system. The patient's nystagmus consisted of two aspects―slow phases directed upward and quick phases altering the direction obliquely right to left downward in turn (square wave jerks). The dominant frequency of the vertical component was 3.1Hz, which was exactly twice as fast as that of the horizontal component at 1.55Hz. Appearance of slow phases of horizontal components suppressed the square wave jerks. Square wave jerks were not only synchronized with quick phases of downbeat nystagmus but also with quick phases of upbeat or torsional nystagmus. Therefore their frequency was not regular but depended on the frequencies of the vertical or torsional component. These data suggest that bow-tie nystagmus is not generated by a common bow-tie nystagmus generator. We propose that bow-tie nystagmus is composed of quick phases of a horizontal component corresponding to the slow phases of the vertical or torsional component which alters its direction left to right in turn in order to avoid lateralization of the position of the eyes.
Electronystagmography (ENG) findings were chronologically studied through the clinical courses in two multiple sclerosis patients (1 male and 1 female, both 25 years of age). At the initial bout, they showed left facial palsy and horizontal gaze nystagmus. The MRI demonstrated a single plaque lesion around the left vestibular nuclei at the ponto-medullary junction in both cases. In ENG recordings of both cases, the slow phase velocities of optokinetic nystagmus (OKN) were severely attenuated bilaterally at onset. In contrast, the smooth pursuit was relatively preserved in both cases through their clinical courses. In several months activities of daily living had recovered to normal. In accordance with their recovery, the OKN finally improved to the normal level in both cases. The Present ENG studies showed a definite dissociation between eye movements of pursuit and optokinetic systems. In Cohen and Raphan's model, the slow phase eye velocity of OKN is comprised of two components: the “direct pathway” involving the flocculus, which is the mechanism responsible for the rapid rise in slow phase eye velocity and is also utilized in mediating ocular pursuit. The second component is the “indirect pathway” which is responsible for producing slow phase eye velocity during vestibular nystagmus, OKN, and optokinetic after-nystagmus (OKAN). A key element in the indirect pathway is velocity storage, which is closely related to the mechanism of the vestibular nuclei. Although the neural circuits that produce velocity storage remain unclear, our previous experimental studies demonstrated that microstimulation mainly in the central medial vestibular nuclei (MVN) of monkeys elicited horizontal nystagmus and after-nystagmus related to velocity storage. Furthermore, after microinjection of muscimol (a GABA-A agonist) into the stimulus effective sites in the MVN, the slow component of OKN, the dominant time constant of aVOR and OKAN transiently disappeared bilaterally. These findings suggested that the horizontal velocity storage is generated in the MVN. The results of our present ENG studies were quite coincident with those of our previous experimental studies. Consequently, in both cases in the present study, it was assumed that the “indirect pathway” was transiently disturbed by the plaque lesion around the VN. In addition, two important points were particularly emphasized. First, the neural networks related to the horizontal velocity storage should be situated at the restricted area of the MVN, mainly the central MVN. Second, a single unilateral vestibular lesion caused a deficit in the horizontal velocity storage in both directions, in a similar manner to the results of studies in the MVN on a single experimental lesion. In conclusion, the findings of the present study and previous studies suggest that the horizontal velocity storage is generated in similar neural circuits of the human vestibular nuclei.
[Introduction] The presence of neuron projection of the peripheral vestibula and the cerebrum was demonstrated by neuroanatomical studies and imaging findings of brain function. I conducted this experiment to examine whether imaginary fixation and deep sensation can suppress nystagmus. [Subjects] Twelve healthy adult volunteers (total 24 ears). [Method] The experiment was conducted as follows: 1. Subjects fitted with infrared Fresnel lenses glass for nystagmus measurement underwent a caloric test (20°C, 5 mL, 20-second stimulation), and nystagmus was recorded. 2. When the slow-phase velocity of nystagmus reached the maximum value, subjects were instructed to raise their arms anteriorly, interlock fingers of both hands tightly, and keep looking in the general direction of their thumbs (as they were fitted with Fresnel lenses, they were unable actually to see their thumbs). 3. After 10 seconds, they were instructed to stop “looking” (could not see in reality) and lower their arms. 4. I compared the slow phase velocity of nystagmus during the 10 seconds before instruction with that during 10 seconds of instruction. [Results] The mean slow phase velocity of caloric nystagmus during loading (stimulation) significantly decreased (p<0.01). The mean slow phase velocity during the 10 seconds before loading (stimulation) was 13.7±4.7°/s, and that during loading (stimulation) was 9.7±3.7°/s. The rate of nystagmus suppression was 28.5±15.7%. [Summary] The study suggested that when imaginary fixation was added to deep sensation, peripheral nystagmus was suppressed.
Pediatric subjects with vertigo are rare in Japan. Benign paroxysmal vertigo (BPV) is a frequent disease similar to orthostatic hypotension. We report herein on a case of BPV in which psychological dizziness had previously been diagnosed. A 5-year-old girl visited our hospital complaining of repeated attacks of vertigo for 3 years. She had intermittent strabismus, and the result of her stabilometry showed functional symptoms, so the doctor who had treated her previously at the age of 4 diagnosed psychological dizziness with visual influence, and observation was started. Her symptoms persisted for 12 months however, and she visited our hospital. Her equilibrium and neurological status were examined. And we asked her family about the situation at the time of attack in detail. Based on the interview, we discovered that she felt fear at the time of attacks, and her family had a history of migraines. Based on our finding, we diagnosed her as having BPV. Vestibular rehabilitation on its own effected a cure. History taking is so important in the diagnosis of BPV, so that we may fully understand the diagnostic criteria prior to examination of pediatric subjects with vertigo.
With regard to the similarities in the social welfare system and cultural background between Korea and Japan, clinical practice for dizziness as well as the entire otolaryngologic practice have a lot in common. The two countries are sharing not only the present issues of medical education, training and healthcare insurance, but also the social demand and requirements for the future, which will be caused by the aging society and the concomitant increment in health care expenditure. Based on an awareness of commonalities and differences between the two countries, we can develop a medical approach for the patients as well as providing worldwide academic leadership. In this paper, I would like to introduce Korea's medical and health care system, and my personal opinions regarding the development of the future relationship between the two countries.
Acoustic neuromas are benign tumors that usually arise within the internal auditory canal from the vestibular nerve. The therapeutic goal of acoustic neuroma surgery is total tumor excision with preservation of the facial nerve and hearing function. Currently, a preservation rate of facial nerve function has been achieved of around 90-95%, so we can give the patient satisfactory results. However, the rate of hearing preservation is still not high. By just preserving the cochlear nerve anatomically, the function of the cochlear nerve which is part of the central nervous system cannot be preserved. In order to preserve the hearing function, we thought that highly sensitive, stable and continuous monitoring would be extremely useful, which can visualize the change of hearing function in real-time. Therefore, we developed a hearing preservation operation using a new method of intraoperative continuous cochlear monitoring. The auditory brainstem response as the conventional way of monitoring hearing function is convenient, but it needs 30 to 60 seconds to achieve average values. To create a quicker and more sensitive monitoring of hearing function, we came up with the idea of placing a special electrode on the dorsal cochlear nuclei. What is most characteristic of our monitoring surgery is to be able to operate while monitoring the status of the hearing function every 6 to 12 seconds without stopping the surgical procedure. We have termed the obtained action potential "DNAP": Dorsal cochlear nucleus action potential. During tumor removal, we observe the amplitude of the DNAP. In the event that a sudden decline is noted, we make it a rule to stop all surgical procedures and wait by 15th of minutes. We emphasize that maximizing the recuperation period in the extended recuperation treatment strategy after reversible injury may improve the outcome after acoustic neuroma surgery. Our hearing preservation rate after acoustic neuroma has improved to more than 70%.
The health care system in Australia, and in particular how patients experience it is described from the perspective of working as a medical officer at the Royal Victorian Eye and Ear hospital (RVEEH) in Melbourne. The Australian health system has both a universal public system called Medicare and a private health sector. Many patients' first contact with the health service is through a general practitioner (GP). Patients can also access public hospitals through emergency departments (ED). For specialized care, patients can be referred to specialists, other health professionals, such as audiologists and optometrists, and hospitals by a GP. At a public hospital, patients are triaged in order to get medical care, not only in the ED but also for specialist consultation and surgery. Private health insurance can cover fees, in whole or part, for treatment by the doctor or doctors of their choice and can result in shorter waiting times for specialist consultation and surgery. Teamwork and collaboration amongst related health professionals are essential for best outcome of patient care. In a multi-disciplinary team, not only doctors but also nurses and other allied health professionals can assume leadership depending on the problems that patients present with. In patients with acute vestibular syndrome, presenting to the ED, it is critical to differentiate between peripheral and central causes, such as a posterior fossa stroke. Detailed history taking and comprehensive neurological examination are crucial, as a false-negative MRI can occur in acute vertebrobasilar strokes. Careful observation of eye movement, abnormal gait and any changes after consultation are especially important. A combination of a head impulse test, skew deviation and direction changing nystagmus (HINTS battery) are also helpful to identify the central lesions. In the Balance Clinic at RVEEH, cases of vestibular migraine, BPPV and multisensory dizziness are commonly seen. Regarding the management of vestibular migraine, prophylactic medication together with lifestyle modification can make a difference to the quality of life. Vestibular physiotherapy plays an important role in reducing symptoms by promoting central nervous system compensation for vestibular dysfunction.