The patch clamp technique enables the analyses of various ion channel characteristics of individual cells in vitro. The most important difference from previous techniques is that the microelectrode (pipette) is firmly attached to the cell surface instead of being inserted into the cells, and the so-called "giga-ohm seal" is attained. Usually, the whole conductance of the cell membrane is measured under "whole cell" and "perforated patch" modes, whereas single channel recordings are also possible by employing relevant modes such as the "cell attached" mode. In the most frequently used "whole cell" mode, the intracellular potential (voltage clamp) or the whole cell current (current clamp) can be kept constant, since the leakage current is very small. Exemplary recordings are also shown from the author's experiments.
[Introduction] I encountered a patient in whom signs of the vasovagal reflex (VVR) developed when the patient underwent the Schellong test , and I also published an article describing the appropriate safety measures for performing orthostatic tests in Equilibrium Research vol. 64(1): 22-28. Specifically, we proposed that an orthostatic test should be discontinued as soon as the patient's heart rate met the relevant diagnostic criteria for the postural tachycardia syndrome (POTS). This conclusion was based on the hypothesis that VVR can be considered equivalent to POTS. I then encountered another patient who demonstrated VVR while performing the Schellong test, as described in Practica oto-rhino-laryngologica:.100(5): 341-347. Therefore, the present study was performed to examine the proportion of VVR patients fulfilling the diagnostic criteria for POTS in the course of an orthostatic test. [Subjects] Six patients who were all diagnosed to have dizziness due to VVR. [Methods] The patients were assessed as to whether or not the maximum increase in their heart rate and the absolute maximum heart rate observed during the orthostatic test fulfilled the following two diagnostic criteria for POTS: (A) a 30/min or more increase in heart rate and (B) an absolute heart rate of at least 120 beats/min. [Results] The mean±S.D of absolute heart rate was 73.0±16.6 beats/min at rest and the maximum heart rate 95.7±18.7 beats/min. The mean±S.D. of maximum increase in heart rate was 22.7±7.7 beats/min. Only 1 (16.7%) of the 6 patients tested met the diagnostic criteria for POTS. [Discussion & Conclusion] As the remaining 5 patients failed to meet the diagnostic criteria for POTS, the hypothesis that "VVR can be considered equivalent to POTS" therefore remains questionable. It is thus considered inappropriate to use only the diagnostic criteria for POTS when assessing the safety in patients undergoing an orthostatic test.
We herein describe two patients with cerebrospinal fluid (CSF) leakage after whiplash injuries, mainly complaining of dizziness and vertigo. After automobile rear-end collisions with whiplash injuries but without head trauma, both patients immediately suffered from headache, vertigo, dizziness, nausea, neck pain and cervico-brachialgia. Neurological examinations were normal in both patients, except for neck tenderness. The RI cisternographies revealed the early filling of bladders within 2 hours and definite CSF leakages at the cervicothoracic junction in one of the patients and at the lumbar portion in the other. The magnetic resonance (MR) images depicted downward displacement of the cerebellar tonsils and the brain stem, and narrowing of the lateral ventricles, presenting an acquired Arnold-Chiari malformation. The patients were consequently diagnosed as having the intracranial hypotension (or CSF hypovolemia) syndrome and underwent several epidural blood patch (EBP) therapies. Transiently their various symptoms improved, but were soon exacerbated once more and have continued until the present. In the electronystagmography (ENG) studies, spontaneous downward nystagmus was observed in a patient in the dark. In the eye-tracking test (ETT), the smooth pursuit was relatively preserved with a saccade superimposed. The most striking finding was that of optokinetic nystagmus (OKN). In both patients, the slow phase velocity was saturated below 60 degrees and could not hold the steady state level in response to a higher stimulus velocity. The frequency of slow phase nystagmus was remarkably reduced. In Cohen & Raphan's model, the slow phase of OKN is supposed to be composed of two components; one is the "direct pathway" which is responsible for a rapid rise. The other is the "indirect pathway" which contains the velocity storage integrator and is responsible for a slower rise and maintaining the slow phase velocity to the steady state level. Our findings suggested the deterioration of both pathways in the slow phase velocity of OKN, that is dysfunctions of the vestibulo-cerebellar interactions. In conclusion, the dizziness and vertigo in the currently reported CSF hypovolemic patients were presumed to be derived from the severe damage especially to the cerebellum and the brain stem, caused by the downward sagging of the brain structures.
Relapsing polychondritis (RP) is a multi-systemic inflammatory autoimmune disease that affects components of cartilage such as collagens and mucopolysaccharide. The most common findings of RP are auricular and nasal chondritis, whereas audiovestibular disorders are rarely noticed at first. We report two cases with relapsing polychondritis who first complained of audiovestibular symptoms. The first patient was a 19-year-old man, who suffered from repeated dizziness, vertigo and bilateral sensorineural hearing loss. One year later, he also had dyspnea caused by chondritis of the respiratory tract and otitis media with effusion. Results of a caloric test and vestibular evoked myogenic potential (VEMP) to clicks showed no response on either side, whereas VEMP to galvanic stimulation showed normal response on both sides. The second patient was a 58-year-old man with repeated vertigo and dizziness. He also had progressive bilateral severe sensorineural hearing impairment. Although he had undergone intravenous steroid therapy, his hearing did not recover. The results of neuro-otological examinations of our patients suggested that recurrent vertigo and dizziness in the patient with RP were mainly of labyrinthine origin.
Three dimensional analysis of the plane that includes each semicircular canal is essential for understanding the vestibule-ocular reflex evoked in each plane. The fact that the semicircular canals do not lie in single planes has been reported. We measured the helical angle of the plane where each semicircular canal existed using a simulated 3D model of the inner ear and a software-based three-dimensional computed tomographic (3D-CT) imaging program. The diameter of each semicircular canal was also measured. The helical angle was the greatest in the anterior semicircular canal both in measurement of the models and the software-based images. The diameter was the greatest in the anterior semicircular canal when measured in the models. It is suggested that the helical angle of the semicircular canal potentially influences the sensitivity of the vestibulo-ocular reflex (VOR) that the semicircular canal evokes in each plane. A sufficient VOR may be evoked in the plane less strictly determined.
We report a case of Bow hunter's stroke with the complaint of cervical vertigo. A 48-year-old man complained of cervical vertigo following head rotation to the left. He showed positional nystagmus when his head was rotated to the left in the supine position and, if the head rotation was maintained, he felt a gradual drop into unconsciousness. The positional nystagmus and fainting were not, however, induced in the patient in the left lateral decubitus position without head rotation. Three-dimensional analysis of his positional nystagmus showed its inconsistent rotational axis, which is different from the single rotational axis in patients with peripheral positional nystagmus. These findings suggested the central cervical positional vertigo/nystagmus in the patients. MRI showed an old infarction of the left cerebellum and MRA showed severe hypoplasia of the left vertebral artery. Vertebral angiography showed severe stenosis of the left vertebral artery and the mechanical occlusion of the right vertebral artery by the atlas-axis joint at C1-C2 when the patient's head was rotated to the left. Therefore, it is demonstrated that his positional vertigo/nystagmus with fainting caused by head rotation to the left was induced by the vertebrobasilar insufficiency due to mechanical occlusion of the vertebral artery associated with head rotation, resulting in the diagnosis of Bow hunter's stroke in this patient.
Most patients with Meniere's disease can be successfully treated with medication. In Japan, since the 1980's we have usually used osmotic diuretics, such as Isosorbide-liquid to control the inner ear endolymphatic hydrops. We have, however, had problems in that Meniere's patients sometimes complain of the tough regimen involving taking Isosorbide-liquid on a daily basis. Recently, Isosorbide-jelly has been developed to improve the medication compliance for patients with Meniere's disease. In the present study, we examined differences between the effects of Isosorbide-liquid and Isosorbide-jelly on hearing and vertigo. We also compared the medication compliance of Isosorbide-liquid with that of Isosorbide-jelly. There were no significant differences in hearing level and vertigo frequency in Meniere's patients before and after Isosorbide-liquid was changed to Isosorbide-jelly. Regarding medication compliance, we should consider which Isosorbide-type we use for each patient on an individual basis.
The recently developed technique of 3-dimensional infrared video-oculography enabled us to record and reproduce 3-dimensional eye movements in a way that is much less invasive than the search coil system. With this equipment, we could draw Listing's plane relative to gravity, which could provide the possibility of evaluating the otolithic function. In this study, the subjects were tilted in the pitch plane, and the change of the orientation of Listing's plane was analyzed using 3D video-oculography. Output from our equipment was in terms of Euler's angle coordinates, which required transcription on a rotational axis reference frame for precise presentation of eye movement. Transcription was accomplished by consecutively combining the rotational quaternions describing the 3 components of Euler's angle. We could reconfirm the counterrotation of Listing's plane with respect to the head so as to remain more earth-vertical. The minimal invasiveness of this examination would allow us to apply it for clinical evaluation of the patients' otolithic function.