Quantitative measurement of airborne particles during endoscopic and microscopic ear surgery in the operating room

OBJECTIVE

This study aimed to quantitatively investigate airborne particle load in the operating room during endoscopic or microscopic epitympanectomy or mastoidectomy.

METHOD

In the transcanal endoscopic ear surgery group, drilling was performed underwater. A particle counter was used to measure the particle load before, during and after drilling during transcanal endoscopic ear surgery or microscopic ear surgery. The device counted the numbers of airborne particles of 0.3, 0.5 or 1.0 μm in diameter.

RESULTS

The particle load during drilling was significantly higher in the microscopic ear surgery group (n = 5) than in the transcanal endoscopic ear surgery group (n = 11) for all particle sizes (p < 0.01). In the transcanal endoscopic ear surgery group, no significant differences among the particle load observed before, during and after drilling were seen for any of the particle sizes.

CONCLUSION

Bone dissection carries a lower risk of airborne infection if it is performed using the endoscopic underwater drilling technique.

Stapediovestibular dislocation with pneumolabyrinth

Traumatic luxation of the stapes into the vestibule is a rare entity, and the disease complicated with pneumolabyrinth is extremely rare. We report the case of a 72-year-old woman with pneumolabyrinth associated with a stapediovestibular dislocation. The patient presented with vertigo and nystagmus following penetrating trauma to the middle ear. High resolution computed tomography scans demonstrated air in the vestibule and dislocation of the stapes. Exploratory tympanotomy demonstrated oozing of the perilymph from the oval window and depression of the stapes into the vestibule. Pneumolabyrinth and stapes luxation detected by high resolution computed tomography should be predictive of a perilymphatic fistula.

Vestibular input to brain monoamine neurons--a review

Yates et al. reported that serotonergic RN neurons are associated with vestibulo-sympathetic responses and may control BP changes during body repositioning (Yates et al., 1992; 1993). Pompeiano et al. demonstrated that LC-NA neurons participate in the postural control and modify the vestibulo-spinal reflex (Pompeiano et al., 1990; 1991a; 2001). Nishiike et al. (1996a) examined the effects of caloric vestibular stimulation on the neuronal activity of LC-NA neurons in rats. The predominant effect of CA with both hot- and cold-water on the electrical activity of LC neurons is inhibitory and persists for several minutes. GABAA receptors located on the postsynaptic membrane of LC neurons are responsible for these inhibitory responses. The VLM may inhibit LC neuronal activity in response to the CA via GABAA receptors (Nishiike et al., 1997). It is suggested that LC-NA inhibition is involved in the development of motion sickness (Nishiike et al., 2001).

Information processing of visually-induced apparent self motion in the cortex of humans: analysis with magnetoencephalography

The cortical site which processes information on whole-body linear displacement is unknown. In this study, neuromagnetic responses to a visually-induced linear vection were recorded in 5 healthy, right-handed, adult subjects using a 122-channel whole cortex neuromagnetometer. We presented expanding rectangles on the screen which came into view one after another and accelerated in expanding speed at random cycle, giving the subjects the sensation of linear self motion (linear vection) through an illusory tunnel with occasional acceleration. Clear responses of magnetic fields related to the accelerative event were obtained in both hemispheres around the parietal and temporal regions. The dipole sources of the component were estimated in the cortex around the superior temporal sulcus, insula and medial superior temporal area. Some parts of these regions may have been comprised in the vestibular cortex, suggesting that it processes the sensation of linear self motion and plays an important role in space perception.

Noradrenergic pathways involved in the development of vertigo and dizziness--a review

In this study, vestibular caloric stimulation (CS) inhibited noradrenergic (NA) neurons of the locus coeruleus (LC) in rats. The vestibular input can be modified by the ventrolateral medulla (VLM), which then inhibits the LC neuronal activity via GABAA receptors. Clinically, CS induces vertigo in humans. Thus, LC-NA inhibition may be involved in the development of vertigo. Moreover, it is speculated that Sopite syndrome, one of the major symptom complexes of motion sickness, is also evoked by LC-NA inhibition. The central LC-NA neuronal system may participate in vertigo and motion sickness independent of the histaminergic neuronal system. In contrast, the cholinergic neuronal system may mediate LC-NA inhibition during the vestibulo-atonomic reflex. The LC-NA system projects to most higher centers and affects sensory information processing. Therefore, it is suggested that the suppression of sensory information processing induced by LC-NA inhibition causes drowsiness, one of the major symptoms of vertigo and motion sickness. It is also speculated that LC-NA inhibition participates in the development of sensory mismatch during vertigo and motion sickness.

[Effects of steroid therapy on long-term canal prognosis and activity in the daily life of vestibular neuronitis patients]

We studied 28 patients with vestibular neuronitis treated at our hospital between 1997 and 1999. To determine the effects of steroid therapy on long-term canal prognosis and daily activity, we examined caloric tests and gave questionnaires to 12 steroid-treated and 16 nonsteroid-treated patients 2 years after onset. We found that canal improvement was 50% in the nonsteroid-treated group and 75% in the steroid-treated one. In cases with severe canal paresis (CP > or = 60%), canal improvement was 33% in the nonsteroid-treated group and 67% in the steroid-treated one. Steroid therapy at the acute stage of this disease significantly reduced the duration of spontaneous nystagmus and handicap in daily life due to dizziness induced by head and body movement, decreasing mood disturbance.

Effect of AF64A, a cholinergic neurotoxin, on footshock stimulation-induced locus coeruleus excitation in rats

We studied the effect of ethylcholine mustard aziridinium ion (AF64A), a cholinergic neurotoxin, on the footshock stimulation (FS)-induced excitation of the locus coeruleus (LC) neurons in rats. The FS-evoked LC excitation was significantly reduced in AF64A-treated rats, in comparison with normal rats. In particular, the early component of LC excitation was less pronounced. The number of choline acetyltransferase immunoreactive neurons in the septal complex was significantly lower than those in normal rats, except for in the ventral subgroup. These findings suggest that the cholinergic neuron system is involved in the early component of LC excitation in rats.

Neural mechanisms of motion sickness

Three kinds of neurotransmitters: histamine, acetylcholine and noradrenaline, play important roles in the neural processes of motion sickness, because antihistamines, scopolamine and amphetamine are effective in preventing motion sickness. Histamine H1-receptors are involved in the development of the symptoms and signs of motion sickness, including emesis. On provocative motion stimuli, a neural mismatch signal activates the histaminergic neuron system in the hypothalamus, and the histaminergic descending impulse stimulates H1-receptors in the emetic center of the brainstem. The histaminergic input to the emetic center through H1-receptors is independent of dopamine D2-receptors in the chemoreceptor trigger zone in the area postrema and serotonin 5HT3-receptors in the visceral afferent, which are also involved in the emetic reflex. Antihistamines block emetic H1-receptors to prevent motion sickness. Scopolamine prevents motion sickness by modifying the neural store to reduce the neural mismatch signal and by facilitating the adaptation/habituation processes. The noradrenergic neuron system in the locus coeruleus is suppressed by the neural mismatch signal. Amphetamine antagonizes mismatch-induced suppression of noradrenergic neural transmission, resulting in preventing motion sickness.

[Seven cases of tuberculous otitis media]

Tuberculous otitis media (TOM) is a variable and puzzling infectious disease that is sometimes confused with other chronic middle ear diseases. A series of 7 cases (9 ears) of TOM recently treated at Osaka Prefectural Habikino Hospital is reviewed to assess the recent features of the disease. In most cases, the pathogenetic mechanism was probably aspiration of tubercle bacilli through the eustachian tube. In most cases, abundant granulations were observed in the middle and external ears, but multiple perforations of the tympanic membrane were not seen. The manifestations were variable, such as otorrhea from the perforation and otitis media with effusion. In their early stage, most cases of TOMs due to transmission via the eustachian tube are tend to resemble otitis media with effusion. Smear tests, culture, PCR, and histopathological examinations, each of which has advantages and disadvantages, must be repeated to achieve a definitive diagnosis. Tuberculin tests can be unreliable, but a chest x-ray is indispensable whenever TOM is suspected. Antitubercular chemotherapy and 2% kanamycin earwash yielded good results. Since the classical criteria for the diagnosis of TOM are no longer valid, we propose a new criterion for diagnosis in the early stage of the disease.

Corticofugal connections between the cerebral cortex and the vestibular nuclei in the rat

The distribution of cortical efferent connections to the vestibular nuclei was quantitatively analyzed by means of retrograde axonal transport of horseradish peroxidase, wheat germ agglutinin-horseradish peroxidase, and Fast Blue in rats. The tracer substances were injected into the spinal vestibular nucleus (SpVe), the caudal part of the medial vestibular nucleus (MVe), and nucleus X of Brown Norwegian rats. Projections to the vestibular nuclei were revealed bilaterally, but predominantly contralaterally from five cortical areas: (1) the parietotemporal region (PT) which occupied the caudal two-thirds of the secondary somatosensory area and spread over the caudal part of the primary somatosensory area and the visceral cortex; (2) the anterior forelimb (AF) overlapping the anterior part of the forelimb area and the transitional zone; (3) the anterior hindlimb (AH) overlapping the anterior part of the hindlimb area and the transitional zone; (4) the lateral forelimb (LF) centered in the intercalated zone lateral to the forelimb area; and (5) the ventrotemporal region (VT) located at the ventral part of the temporal cortex. In addition to these cortical fields, the frontal cortex was found to project directly to the vestibular nuclei. These corticofugal projections were verified in experiments in which biocytin was injected into the rat PT. Anterogradely labelled fibers were traced predominantly contralaterally to the SpVe, caudal part of the MVe, and nucleus X. It is suggested that the rat corticofugal projections to the caudal vestibular nuclei modify vestibular reflexes to assist in coordinating eye, head and body movements during locomotion.

Cholinergic influence on vestibular stimulation-induced locus coeruleus inhibition in rats

In our previous study, caloric stimulation (CS) of the vestibular apparatus inhibited noradrenergic neuronal activity in the locus coeruleus (LC) in urethane-anaesthetized rats. Therefore, the inhibition of LC noradrenergic neurons is involved in vestibulo-autonomic responses. Since motion sickness can be cured by scopolamine, cholinergic neuron system may also be involved in vestibulo-autonomic responses. The present study examined the effects of intracerebroventricular injection of ethylcholine mustard aziridinium ion (AF64A), a presynaptic cholinergic neurotoxin, on CS-induced LC inhibition. In AF64A-treated rats, the CS-induced LC inhibition was less pronounced than in normal rats. In a subsequent series of experiments, the intravenous injection of scopolamine blocked the CS-induced LC inhibition. These findings suggest that central cholinergic neurons are associated with noradrenergic neuronal inhibition during the vestibulo-autonomic reflex.

Co-localization of glutamate, choline acetyltransferase and glycine in the mammalian vestibular ganglion and periphery

Glutamate (Glu) is considered to be the main transmitter at the central synapses of primary vestibular afferents (PVA) and glycine (Gly) is assumed to play a modulatory role. In the vestibular periphery a transmitter role for acetylcholine (ACh) has been attributed chiefly to vestibular efferents (VE), however only a subset of VE neurons displays immunoreactivity (ir) for choline acetyltransferase (ChAT) and acetylcholine esterase (AChE). Controversial results exist on the presence of these two enzymes in PVA. In this study the presence of Glu, ChAT, Gly and their co-localization in the vestibular ganglia (VG) and end organs of mouse, rat, guinea pig and squirrel monkey were investigated. In the VG all bipolar neurons display strong Glu-ir and the majority of cells show a graded ChAT-ir and Gly-ir in all species examined. ChAT and Gly are present in highly overlapping neuronal populations and with a similar gradation. In the end organs ChAT and Gly are again co-localized in the same sets of fibers and endings. In conclusion, in the vestibular ganglion and end organs ChAT appears also to be present in primary afferents rather than being restricted to efferent processes. ChAT in primary afferents might indicate a modulatory or co-transmitter function of acetylcholine.

Histaminergic influence on vestibular stimulation-induced locus coeruleus inhibition in rats

In previous reports we have shown that caloric stimulation (CS) of the vestibular apparatus inhibits locus coeruleus (LC)-noradrenergic neuronal activity in urethane-anaesthetized rats. The present study examined the effect of neural histamine depletion by alpha-fluoromethylhistidine (alpha-FMH) on CS-induced LC inhibition. In alpha-FMH treated rats, LC neuronal inhibition caused by CS was still observed. This finding indicates that the central histaminergic neuron system does not participate in the CS-induced LC-noradrenergic inhibition. It is suggested that the noradrenergic neuron system is involved in the development of vestibulo-autonomic response, independent of the histaminergic neuron system.

[Clinical features in patients with delayed endolymphatic hydrops]

We report clinical features in patients with delayed endolymphatic hydrops (DEH) with juvenile unilateral deafness. Among 23 patients with DEH, 15 cases were diagnosed as ipsilateral DEH and 8 cases as contralateral DEH. The distribution of onset age showed two peaks at ages of < 30 years and > 40 years. In 80% of the ipsilateral DEH cases, the onset of episodic vertigo was at younger ages. On the other hand, in 75% of the contralateral DEH cases, the onset of fluctuation hearing loss of the contralateral ear was at older ages. Ispilateral DEH and Meniere's disease may show different pathophysiologies. The incidence of dominant negative summating potential in the better-hearing ear was 20% in the ispilateral DEH cases and 60% in the contralateral DEH cases. It is suggested that endolymphatic hydrops is in the better-hearing ear of contralateral DEH.

Antidromic burst activity of locus coeruleus neurons during cortical spreading depression

The electrical activity of locus coeruleus neurons was investigated during cortical spreading depression in urethane-anaesthetized rats. Cortical spreading depression was induced by a direct application of 1-3 M KCl solution to the surface of the cerebral cortex. The occurrence of cortical spreading depression was assessed by recording negative d.c. shifts and in some experiments by monitoring the extracellular potassium concentrations. The mean spontaneous firing rate of locus coeruleus neurons was significantly reduced during cortical spreading depression. Approximately 60% of locus coeruleus neurons recorded during cortical spreading depression revealed anomalous burst activity consisting of multiple initial segment spikes as well as full initial segment-somatodendritic spikes with a marked initial segment-somatodendritic break. Each spike of the cortical spreading depression-related burst activity occurred at intervals ranging from 15.0 ms to 90.1 ms (34.9 +/- 0.5 ms). The burst activity appeared unpredictably at variable intervals in a phasic or tonic manner during cortical spreading depression. The cortical spreading depression-related burst activity of locus coeruleus neurons mimicked antidromic spikes induced by train stimulation of the cerebral cortex at short interspike intervals during iontophoretic application of GABA to locus coeruleus neurons, whereas it was totally different from synaptically-activated burst activity induced by tail pinch. The full spikes and initial segment spikes in the cortical spreading depression-related burst activity failed to collide with cortically elicited antidromic spikes, even when they appeared within the collision interval. The proportion of initial segment spikes in the cortical spreading depression-related burst activity was reduced following an increase in membrane excitability by iontophoretic application of glutamate, and increased during a decreased membrane excitability by GABA application. The antidromic burst activity of locus coeruleus neurons also appeared for a short time during cortical spreading depression prior to the occurrence of seizure waves induced by GABA antagonists, while the burst activity could not be observed during seizure activity. These results indicate that the cortical spreading depression-related burst activity was of antidromic origin and that the marked initial segment-somatodendritic break in spontaneous spikes of locus coeruleus neurons during cortical spreading depression was due to reduced excitability of the somatodendritic membrane. The cortical spreading depression-related burst activity may cause release of a large amount of noradrenaline in vast regions of locus coeruleus terminal fields through the numerous axon collaterals, thereby playing a role in functional changes of brain neurons related to cortical spreading depression.

[Clinical features and utricular dysfunction in patients with benign paroxysmal positional vertigo]

We report the clinical features in patients with benign paroxysmal positional vertigo (BPPV), who met the following criteria; (1) a history of brief episodes of positional vertigo, and (2) a characteristic torsional paroxysmal positional nystagmus that was observed visually. The mean age of onset was 55 years. There was no sex predominance. In most patients, positional vertigo disappeared within 2 months. We then used the eccentric rotatory test to examine the patients otolithic function. In the eccentric rotatory test, a patient is rotated around an axis located behind his head (eccentric rotation, ECR). We have demonstrated that the enhancement of vestibulo-ocular reflex (VOR) gain in ECR can be used as an index of the utricular function. Enhancement of VOR gain was observed in ECR to the lower ear in positional vertigo, but not to the uppermost ear. The findings suggest an imbalance in utricular function in patients with BPPV. Otoconia dislodged from the deranged utricle may be a source of canalolithiasis/cupulolithiasis.

Neurons in rostral ventrolateral medulla mediate vestibular inhibition of locus coeruleus in rats

The effects of caloric vestibular stimulation on the central noradrenergic neurons system were examined in the rat. In urethane-anesthetized rats, caloric stimulation inhibited the spontaneous activity of noradrenergic locus coeruleus neurons and increased systemic blood pressure. Electrical and chemical lesions in the ventrolateral medulla attenuated both the locus coeruleus inhibition and the blood pressure increase in response to caloric stimulation. Neither the neuronal inhibition nor the pressor effect was attenuated by any deafferentation of the forebrain or baroreceptors, or lesioning of the nucleus tractus solitarius. These findings indicate that the caloric stimulation-induced locus coeruleus inhibition is mediated by neurons in the ventrolateral medulla, and that these neurons also mediate the vestibulo-pressor responses. The locus coeruleus inhibition via the ventrolateral medulla is, however, considered to be independent of ventrolateral medulla-mediated systemic pressor effect. Collectively these findings suggest that the ventrolateral medulla is the major origin of inhibitory vestibular input to the noradrenergic neurons of the locus coeruleus, and that the ventrolateral medulla plays an important role in the vestibulo-autonomic response.

GABAergic inhibitory response of locus coeruleus neurons to caloric vestibular stimulation in rats

We examined the effects of caloric vestibular stimulation on the neuronal activity of the locus coeruleus (LC) in urethane-anesthetized rats. The middle ear cavity was irrigated with hot (44 degrees C) or cold (30 degrees C) water through a polyethylene tube. Most neurons (hot water: 76%, 55/72; cold water: 90%, 19/21) exhibited suppression of neuronal discharge in response to caloric stimulation. The suppression of LC neuronal discharge following caloric stimulation occurred with a long latency (approximately 80 s), and lasted a long period of time (approximately 3 min). Neither caloric stimulation of the auricle, nor irrigation of the middle ear with water at 37 degrees C, nor caloric stimulation of the middle ear after labyrinthectomy inhibited LC neuronal discharge. The caloric stimulation-induced LC neuronal inhibition was significantly attenuated by the intravenous injection of picrotoxin and by the iontophoretic application of bicuculline methiodide. These findings indicate that the predominant effect of caloric vestibular stimulation on LC neuronal discharge is inhibitory, and that the caloric stimulation-induced LC neuronal inhibition is mediated by GABAA receptors located on the membrane of LC neurons. It is suggested that the suppressed activity of noradrenergic LC neurons is involved in the vestibulo-autonomic reflex.

[Three cases of Lermoyez's syndrome and its pathophysiology]

Two cases of bilateral Lermoyez's syndrome and one case of unilateral Lermoyez's syndrome are reported. The patients had recurrent episodes of vertigo with improvement of hearing or tinnitus, which is characteristic is Lermoyez's syndrome. In case 1, a 48-year-old female, dehydration with glycerol or furosemide induced nystagmus and improved bilateral hearing and the gain of the vestibulo-ocular reflex, while overhydration with drinking water impaired bilateral hearing with disappearance of nystagmus. These findings indicate that she had endolymphatic hydrops in both ears, suggesting that simultaneous changes in bilateral cochlear and vestibular function induce Lermoyez's syndrome. In case 3, a 52-year-old female, which we already reported, endolymphatic collapse in both ears may have changed bilateral inner ear function, resulting in Lermoyez's syndrome. On the other hand, patients 2, a 47-year-old male, experienced a vertigo attack with improvement of unilateral hearing after defibrinogenation therapy. In this case, slowly developing insufficiency of the inner ear blood supply may have caused the gradual hearing loss. It seemed that decreasing blood viscosity by defibrinogenation allowed blood to rush into the labyrinth, causing vertigo but at the same time improving hearing. We proposed that there are two types of Lermoyez's syndrome, bilateral (cases 1 and 3) and unilateral (case 2).

Effects of caloric vestibular stimulation on prepositus hypoglossi neurons in rats

In our previous study, we found that the majority of locus coeruleus (LC) neurons were inhibited by caloric stimulation and that the inhibition was mediated by gamma aminobutyric acid (GABAA) receptors. It has been reported that the nucleus prepositus hypoglossi (PrH) sends GABAergic inputs to the LC. In the present study, an attempt was made to determine whether PrH neurons contribute to the LC neuronal inhibition caused by caloric stimulation. We characterized the neuronal response in the PrH to caloric stimulation in rats. About three-fourths of PrH neurons showed various responses to both ipsi- and contralateral caloric stimulation, suggesting that PrH neurons receive bilateral vestibular inputs. However, these neurons were not activated by antidromic stimulation of the LC. The remaining one-fourth of the PrH neurons that were antidromically activated did not respond to caloric stimulation. Lesions in the PrH did not attenuate the LC neuronal inhibition caused by caloric stimulation. These findings suggest that the inhibition of LC neurons caused by caloric stimulation is not mediated by the PrH.

Antagonizing effects of VA-045 on reduced activity of rat locus coeruleus neurons following head injury or intravenous injection of clonidine

Based on the finding that VA-045, a novel apovincaminic acid derivative, had improved disturbance in consciousness, we examined the effects of the drug on the electrical activity of locus coeruleus (LC) neurons in animal models of consciousness disturbance. The animal models of consciousness disturbance used in this experiment were closed head injury (CHI) and intravenous injection of clonidine. CHI as well as clonidine injection reduced the spontaneous activity of LC neurons. The reduction of the spontaneus activity of LC neurons following CHI or clonidine injection was restored by intravenous injection of VA-045. The change of LC neuronal activity induced VA-045 preceded desynchronization of EEG. These results suggest that VA-045 exerts its ameliorating effect on consciousness disturbances, at least in part, by augmenting the spontaneous activity of noradrenergic LC neurons.

A long-lasting change in the excitability of fetal brain neurons following activation of dam's hypothalamus in rats

The influence of the dam's brain on the electrical activity of brain neurons was examined in the rat fetus while the fetus was still connected to the dam by the umbilical cord. Under urethan anesthesia, the spontaneous or glutamate-induced discharge of single brain stem neurons in fetuses was decreased by electrical stimulation of the dam's hypothalamus (Hyp). The changes occurred 21-122 s after start of the stimulation and persisted throughout the recording until the cells were lost after 2.4-9.5 min. The effects of electrical stimulation of dam's midbrain reticular formation (MRF) were much weaker and of shorter duration compared with Hyp stimulation. The dam's blood pressure was increased immediately after the beginning of MRF or Hyp stimulation. The change was always greater with MRF than with Hyp stimulation. Activation of the dam's MRF and Hyp had no marked influence on the blood flow in the fetal brain. These results indicate the presence of a functional interaction between the brain of the dam and that of its fetus mediated through the placenta.

[Diagnostic and therapeutic problems in vestibular neuronitis: clinical implications for sudden vertigo]

We defined sudden vertigo as a sudden, unilateral peripheral vestibular dysfunction. The criterion for its diagnosis is a single episode of vertigo without cochlear and central symptoms. Among 20 patients with sudden vertigo there was no difference in clinical aspects between those with CP (canal paresis) (CP% > or = 25%) and those without CP (CP% < 25%). This suggests that sudden vertigo with CP is due to sudden vestibular dysfunction with predominant involvement of the lateral semicircular canal. Basically, vestibular neuronitis is considered to be due to acute unilateral neuropathy of the vestibular nerve. However, since we have no routine examination for evaluating vestibular nerve function, sudden vertigo with CP should be diagnosed as vestibular neuronitis. We then assessed the prognosis of sudden vertigo with CP (vestibular neuronitis). About two years after the onset of CP 4 of 10 patients had recovered. However, patients with persistent CP had a handicap in their everyday life because of the dizziness induced by head movements. The possibility of recovery of vestibular function in response to steroid therapy may improve the prognosis in vestibular neuronitis.

Responses of locus coeruleus neurons to caloric stimulation in rats

We examined the effects of caloric stimulation on the neuronal activity of the locus coeruleus (LC) and of the vestibular nucleus complex (VNC) in urethan-anesthetized rats. The single unit activity of neurons in the LC and VNC was extracellularly recorded. A polyethylene tube for caloric stimulation was inserted into the middle ear cavity on the ipsilateral side. Through the tube, the middle ear was irrigated by hot (44 degrees C), cold (30 degrees C), and ice (4 degrees C) water. The majority of neurons in the VNC showed excitation by middle ear irrigation with hot water and inhibition by ice-water irrigation. The responses occurred during caloric stimulation and disappeared immediately after the cessation of the stimulation. The results suggest that the responses of VNC neurons to caloric stimulation directly reflect changes in primary vestibular afferent activity. On the other hand, the predominant effect of caloric stimulation with hot and cold water on LC neuronal activity was inhibitory. The suppression of LC neuronal activity occurred approximately 1 min after the cessation of the caloric stimulation and persisted for 3-5 min. The results suggest that LC neurons receive processed vestibular signals. Motion sickness and vestibular dysfunction induced by caloric stimulation cause emesis, which is known as vestibulo-autonomic response. The vestibulo-autonomic syndrome can be prevented by amphetamine, a noradrenaline releaser. Therefore, the inhibitory response of noradrenergic LC neurons to vestibular stimulation may be involved in the vestibulo-autonomic response.

[Multivariate analysis of everyday handicap of patients with dizziness]

A preliminary questionnaire consisting of 30 questions was developed to evaluate handicaps in everyday life for 105 patients with dizziness. Factor analysis divided the questions into 5 principal factors of handicap due to dizziness: 1) disturbance of social activity, 2) body motion precipitating dizziness, 3) limitation of physical activity, 4) emotional disturbance, and 5) disturbance of interpersonal communications. The score of each factor was calculated as the sum of the scores of three principal questions in the corresponding factor. There was no contribution of clinical diagnosis, patient's age or gender, or duration of the disease to the score of each factor. Thus, it is concluded that the reorganized questionnaire which consists of three principal questions in 5 factors can be used for evaluating dizziness handicaps in everyday life. The score of the emotional factor in patients with Meniere's disease was higher than that for other vestibular disease. The score of the body motion factor in patients with vestibular neuronitis was higher than that for vertebro-basilar artery insufficiency. Thus, the re-organized questionnaire can also be used for evaluating the contribution of each factor to dizziness handicaps in everyday life.