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To identify an eventual vascular aetiology in different diseases with sensorineural hearing loss (SNHL), the cochlear blood flow (CoBF) was measured using laser Doppler flowmetry (LDF) in 69 patients with Ménière's disease (MD), 38 patients with progressive SNHL and 8 patients with sudden deafness. The mean CoBF amplitude at rest was 0.70 mV (SD 0.25) for patients with MD, 0.66 mV (SD 0.21) for patients with SNHL and 0.69 mV (SD 0.23) for those with sudden deafness. No statistically significant difference was observed between the groups with respect to the CoBF amplitudes at rest or during the Valsalva manoeuvre. There was a statistically significant correlation (r = -0.4, p < 0.05) between the hearing level and CoBF amplitude in the SNHL group only. It is concluded that the reduction in vascular flow may not be the main aetiological factor in Ménière's disease or sudden deafness. In SNHL the correlation of hearing level with the level of the LDF amplitude can be secondary to the progression of hearing loss.

Machine learning methods such as neural networks, decision trees and genetic algorithms can be useful to aid in the classification of patients. We tested Kohonen artificial neural networks, which are known to be effective for classification tasks. Our sample included patients with six different diseases. The Kohonen network algorithm recognized the four largest groups reliably, but the two smallest groups were too small for the method. Neural networks seem to be promising for the computer-aided classification of otoneurological patients provided that the number of patients used is sufficiently large.

We studied the use of virtual reality technology as a stimulus in balance examinations. A pilot study was made using a small group of healthy subjects to investigate the effect of alcohol and virtual reality stimulus on the subjects' balance. The tests showed that blood alcohol concentration accounted for almost 50% of the increased lateral body sway velocity. The new stimulus technique based on virtual reality technology seems to be effective and flexible for postural investigations.

The aim of the study was to evaluate aetiological factors for postoperative headache after vestibular schwannoma (VS) surgery with respect to asymmetric activation of vestibular reflexes. After surgery, 27 VS patients with persistent postoperative headache, 16 VS patients without headache and 9 healthy controls were examined. The vestibular, cervicocollic and cervicospinal reflexes were evaluated to study whether asymmetric activation of vestibular reflexes could cause headache. The effect of neck muscle and occipital nerve anaesthesia and the effect of sumatriptan on headache were also evaluated. The vestibular function of VS patients with headache did not differ from that of VS patients without headache, but was abnormal when compared to that of normal controls. The cervicospinal and cervicocollic reflexes did not differ in the patient groups. Injection of lidocaine around the operation scar gave pain relief to two patients, and one of them had occipital nerve entrapment. Infiltration of lidocaine deep in the neck muscles in the vicinity of the C2 root did not alleviate headache, but caused vertigo. Nine patients with musculogenic headache got pain relief from supportive neck collars, and two patients with cervicobrachial syndrome got pain relief from manual neck traction. The study shows that asymmetric activation of cervicocollic reflexes does not seem to be the reason for headache. Headache seems to be linked to neuropathic pain, allegedly caused by trigeminal irritation of the inner ear and the posterior fossa, which has recently been linked to vascular pain.

The purpose of the study was to evaluate the usefulness of hearing preservation in vestibular schwannoma (VS) surgery. Hearing preservation was attempted in 123 of 383 patients operated on during the years 1979 to 1993 at Helsinki University Hospital. Hearing was preserved in 47 cases. Pure-tone averages (PTA) better than 30 dB were found in 12 cases postoperatively. Seventy percent of the patients rated their hearing preservation as valuable or very valuable. Only 8% did not find hearing preservation useful. Postoperatively, tinnitus was present in 62% of the patients, and it was a moderate problem in only 23% of the patients. In only one subject was the tinnitus a handicap that reduced the quality of life. Based on these experiences, we encourage surgeons to continue efforts to preserve hearing in VS surgery.

Basic fibroblast growth factor (bFGF) has significant properties in wound healing, tissue regeneration and ulcer repair of the upper digestive tract. The purpose of the present study was to identify and analyse factors affecting the concentration of bFGF in saliva from healthy human individuals. A commercially available enzyme-linked immunosolvent assay kit (ELISA) was used for the analyses of bFGF in saliva. In total, 56 samples were collected from 28 healthy subjects, 15 male and 13 female. Determination of bFGF was performed by spectrophotometer (wavelength 490 nm). bFGF was detected in all samples. Mean bFGF concentration was 0.87 pg/ml (SD 0.49) and the concentration ranged from 0.3 to 1.9 pg/ml. In subjects aged 22 to 49 years, no age-dependent variation in bFGF was present, females did not differ from males, and no difference was evident between European and Asian subjects. Smokers had significantly higher saliva concentrations of bFGF than non-smokers. Since bFGF, together with other growth factors, is involved in wound healing and tissue repair, we suggest that bFGF in saliva is involved in the reparative processes of mucous membranes.

A large family with mid onset sensorineural hearing loss (HL) was used to study the effect of environmental factors on progression HL. Data from five-generations of one family were traced and 104 living members were included in the study. Audiograms were measured for 60 family members. We used an expert program to study the individual risk factors, which included the known risk factors for sensorineural HL. The pattern of inheritance in this HL family was autosomal dominant and 22 individuals were affected. The HL among affected individuals was symmetrical and varied from mild to severe. The mean age at onset of HL was 22 years. The mean deterioration of hearing at 2 kHz frequency was 1 dB/year. In the risk analysis the use of NSAID-analgetics and military noise exposure correlated with HL. There was no correlation between occupational and free time noise-exposure and HL. Analgetics may aggravate the HL in subjects with inherited HL. This type of genetic lesion is new and is not in those chromosomal areas already documented in the literature.

The aim of this study was to evaluate the effect of operation on tinnitus in vestibular schwannoma (VS) patients. Altogether, 251 VS patients who underwent surgery during the years 1979 to 1993 at Helsinki University Central Hospital were included in the study. Information on preoperative tinnitus was collected from previously acquired data and postoperative tinnitus was evaluated. Preoperatively, 62.6% of the patients had experienced tinnitus. Of those with preoperative tinnitus, 47.4% also had it postoperatively, but of those 93 patients without preoperative tinnitus, 39.8% had tinnitus postoperatively. Tinnitus is one of the primary symptoms of VS, together with hearing impairment and disequilibrium. The risk of postoperative tinnitus is almost 40%, and with preoperative tinnitus, the risk is 7.6% higher. In the majority tinnitus was not related to the surgery. Only a few patients had severe problems with tinnitus; difficulty understanding speech was the major complaint.

We retrieved information on 128 patients with vestibular schwannoma (VS) and 243 patients with Ménière's disease (MD) from the database of the otoneurologic expert system (ONE). The patients filled in a questionnaire concerning their symptoms, earlier diseases, accidents and tobacco and alcohol use. This information was then integrated with results of audiometric, otoneurologic and imaging studies. Forty-nine (38%) of the VS patients had the full triad of vertigo, hearing loss and tinnitus. The vertigo mimicked that in MD in 18 (14%) patients. The mean age of these patients was 48 years. There were 7 men and 11 women. The tumour was small (< 2 cm) in eight patients and medium-sized (2-4 cm) in seven patients. The mean attack duration in these 18 patients ranged from 5 min to 4 h. The attacks most commonly (69%) occurred only once or twice a year. Their intensity was moderate. Half of the patients had spontaneous nystagmus. Caloric asymmetry > 25% was detected in 61% of the patients. Tinnitus in these patients was mostly (49%) mild. Intense tinnitus was present only in 12% of patients. Headache was present in 25% of these patients.

The development of laser Doppler flowmetry techniques has contributed greatly to the study of cochlear blood flow (CBF). In animal models, intravenous betahistine dihydrochloride clearly increased CBF in a dose-dependent manner. This effect was greater in the cochlear vasculature than in the systemic vascular bed. The effects of betahistine were blocked by the alpha 2-antagonist idazoxan, thus suggesting an interaction between histaminergic and presynaptic adrenergic receptors. This was further supported by studies investigating the effects of electrical stimulation on CBF. Local (round window membrane) application of betahistine did not affect CBF, but had a non-specific effect on cochlear electrophysiology. This indicates that the receptors for betahistine vascular effects in the inner ear are most likely located in the modiolar artery. More recently, laser Doppler flowmetry techniques have been applied to human subjects. It has been shown that intratympanic application of adrenaline affects CBF and that this blood flow is under vigorous sympathetic control. Electrical stimulation has also been used to obtain measures of dynamic responsiveness in human subjects. This results in an increase in CBF, which is dependent on the intensity of the stimulation. Preliminary evidence indicates that this procedure can provide a standardized measure of the dynamic properties of CBF and may provide a means to differentially identify patients with compromised vasculature.

We retrieved information on 59 patients, 19 men and 40 women, with benign paroxysmal positional vertigo (BPPV) from the database of the otoneurologic expert system (ONE). The original number of patients was greater, but we excluded all those with hearing loss of any origin. The patients filled in a questionnaire concerning their symptoms, earlier diseases, accidents and tobacco and alcohol use. This information was then integrated with results of audiometric, otoneurologic and imaging studies. The mean age at onset of symptoms was 44 years. Most patients had had vertiginous spells for < 1 year. None of the patients had hearing loss. Tinnitus was experienced by 32% of patients, and these patients experienced more anxiety than the others [r(53) = 0.40, p < 0.01]. The mean duration of the vertigo attacks ranged from a few seconds to 5 min, and they were fairly mild (26%) or moderate (41%) in intensity. The attacks were perceived as more intense if vertigo was rotational [r(54) = 0.60, p < 0.01] or if it was accompanied by nausea [r(58) = 0.42, p < 0.01]. Patients with headache had more intense attacks [r(58) = 0.36, p < 0.01]. The vertigo attacks occurred in spells; patients had several attacks a week (23%) or during the course of 1 day (52%). The vertigo was rotational in 80% of patients, and 47% experienced a floating sensation. The floating vertigo was most often provoked by pressure changes [r(54) = 0.41, p < 0.01] or changes in visual surroundings [r(54) = 0.52, p < 0.01].

At lower power, lasers fuse collagen fibres and weld tissues. Welded collagen fibres make a solid bond and allow tissue growth along the bonded edges. Our aim was to study applicability of lasers in myringoplasty. We used a KTP-532 laser in outpatient myringoplasty. The laser beam was delivered through a micromanipulator connected to a microscope or through a 200-400-micron silica fibre. The perichondrium was used for transplantant and harvested from the tragus. The margins of the perforation in the eardrum were evaporated, with the laser operating in a continuous mode at 2-4 W. The middle ear was filled with gelfilm to provide support for the transplant. The perichondrium was placed under the margins of the tympanic membrane and lazed at low power (0.2-1.5 W) in continuous mode. In pale tissues, venous blood, methylene blue or fluorescein was used to enhance the tissue admittance of laser energy. Surgical failures were linked to thermal tissue damage due to excessive energy during lazing. In two cases, visibility via microscope into the anterior edge was not complete and the transplantant did not adhere in the relatively limited area. One patient had epidermal growth under the tympanic membrane and developed local cholesteatoma. Laser-assisted myringoplasty provides several advantages over traditional myringoplasty: it is minimally invasive, no manipulation of the ossicles is needed and it is convenient in anterior perforations, where it can be done endoscopically. We prefer a fibre delivery system to a micromanipulator, as lazing with endoscopes is possible and thermal damage is easier to prevent.

We examined whether tension neck (TN) may due to inadequate proprioceptive and vestibular activation of the cervico-collic reflex (CCR). CCR and vestibulospinal responses (VSRs) were recorded from 106 forest workers by stimulating the neck, lumbar or calf proprioceptors by vibration. The VSRs were recorded with posturography. TN occurred in 27 out of 106 subjects. The subjects with TN (48.5 years) were older than those without TN (43.1). The mean body sway during quiet stance was the same in both groups during the neck stimulation. In subjects with tension neck stimulation of neck or lumbar proprioceptors caused excessive, unpredictable body excursion in the lateral and anteroposterior direction that continued after stimulation. Results from stimulation of lower limb proprioceptors did not significantly differ between the 2 groups. In logistic regression analysis a model to predict TN consisting of perstimulatory postural stability (odds ratio 1.4) and poststimulatory postural stability (odds ratio 1.8) turned out to be statistically significant. The anatomical findings of CCR in the medulla oblongata suggest that neck muscle afferents control the posture and muscle activity of the neck. The erroneus facilitation of proprioception in TN subjects indicate that TN may be raised by inadequate facilitation of CCR.

We examined voluntary eye movements of 20 ophtalmologically screened patients (mean age of 51 years) with operated hemangioblastoma (HAB) in the cerebellum. Constant and pseudo-random saccades and pseudo-random smooth pursuit eye movement (PRPEM) test (with 4 frequency combinations) were evaluated. As controls 38 healthy subjects were examined. In the logistic regression analysis latency and accuracy of constant saccades were the best predictors for operated HAB with correct overall classification rate of 79.3%. Accuracy was worse and latency longer in operated HAB group than in control group. In pseudo-random saccades correct classification between the groups was achieved in 82.8% of all cases with latency and accuracy as predictors. In PRPEM test the best frequency combinations in differentiating operated HAB patients from controls were 0.25 and 0.425 Hz for gain, and 0.3 and 0.7 Hz for phase and gain, the correct overall classification rate being 73.3% in both cases. The characteristic changes in voluntary eye movements after removal of cerebellar hemangioblastoma seem to be insufficient timing of initiating the eye movement.

Dizziness is a common symptom in elderly people. Head autorotation test (HART) has earlier shown no significant vestibulo-ocular reflex (VOR) disturbances in healthy elderly subjects. We used our recently developed HART to determine VOR in 14 elderly volunteers without otoneurological diseases and sedative medications. Gain and phase were determined in 5 frequency bands from 0.5 to 5 Hz. The gain of the elderly was significantly increased to 1.11-1.27 in the frequency range of 3-5 Hz compared with the controls. The phase lead of 7-8 degrees in the frequency bands of 2 and 4 Hz differed significantly from normative values of the controls. The percentage of the elderly to reach high-frequency head movements was diminished to 50% in the frequency band of 3 Hz and to 36% in the frequency band of 4 Hz (controls 100% and 95%, respectively). The individual HART results were abnormal in 86% of the elderly. The high-frequency VOR of the elderly was inaccurate in magnitude and timing. More than half of aged subjects were not able to generate voluntary fast head movements. These findings may explain the high prevalence of dizziness and falls in elderly subjects.

A sudden or progressive hearing loss in the only hearing ear is an otologic emergency, in which therapeutic possibilities are limited. We describe results of immunosuppressive therapy in 10 patients with one deafened ear either due to cochlear hydrops or Meniere's disease, who developed progressive or fluctuant hearing loss in the only hearing ear. The perilymphatic fistula was excluded with tympanoscopy. Azathioprine (25 mg t.i.d.) with prednisone (initial dose 20-40 mg with daily dose of 5-15 mg/day) was used. The hearing of 6 subjects responded to treatment. The initial pure tone audiogram (PTA) at speech frequencies of the "only hearing ear" was 57.3 dB HL with speech discrimination score (SDS) of 85%. The hearing improvement occurred successively within days or weeks. The average improvement of PTA was 22.4 dB HL after the mean treatment period of 5 weeks. In contralateral ear (the average PTA and SDS were 72.5 dB HL and 28%, respectively) the mean improvement in PTA was insignificant (4.4 dB). In 5 patients with vertigo it was improved in 3 cases. Cortisone alone or with combination of cyclophosphamide or ciclosporine was not effective in our hands.

In this study data of voluntary eye movements 62 patients (mean age was 49.6 years) with Meniere's disease and 38 healthy control subjects were examined. Pseudo-random smooth pursuit (PRPEM) tests were conducted with frequency combination of 0.25 and 0.425 Hz. Saccades at constant targets and pseudo-randomly shifting targets were evaluated. In logistic regression analysis constant saccades correctly classified the cases in 57% as saccadic latency discriminating the groups best, latency being longer in Meniere group. In pseudo-random saccades, correct classification was achieved in 75.4% of all cases as latency discriminating the groups best, and latency was longer in Meniere group. In PRPEM, correct classification was achieved in 65.3% of all cases as gain by amplitude (GA), discriminating the groups best, and GA was smaller in Meniere group. Pseudo-random saccade test is a demanding task and that may explain why a peripheral vestibular lesion may interfere visual tracking and scanning performance. Latency is the most vulnerable of parameters to be lesioned. Results indicate that a peripheral vestibular lesion influences the control of voluntary eye movements and may explain the complaints of visual targeting on objects that patients with Meniere's disease have.

The aim of the study was to investigate the possible signs of chronic spirochetal infection in 27 children with a history of facial paralysis with onset of symptoms during May-October 1985-1993. These children had not been studied at the time of facial paralysis for possible Lyme borreliosis and none of these children had received antimicrobial therapy at that time. The patients were interviewed with special reference to symptoms and signs of Lyme borreliosis and thereafter examined clinically and with laboratory tests. None of the patients showed signs or symptoms of chronic Lyme borreliosis. One child-now a 14-year old girl-had a 4-fold rise in serum Borrelia burgdorferi antibodies as a sign of a recent infection. According to our prospective studies on pediatric facial paralysis in Finland (over 50% of children presenting with facial paralysis during May-October have Lyme borreliosis), we have a reason to assume that at least some in our study group had a facial paralysis caused by Borrelia burgdorferi infection. The results of our study indicate that facial paralysis has a favorable prognosis and in short-term follow-up the children do not have symptoms or signs of chronic Lyme borreliosis.

The etiology of many diseases involving vertigo is still unknown although the same etiologic factors have been suggested for several diseases. In most cases the diseases are diagnosed on the basis of exclusion-other possible causes being ruled out before the diagnosis can be confirmed. Benign recurrent vertigo (BRV) has been defined as spells of vertigo characteristic of Menieres disease without auditory or clinical neurologic symptoms and signs. The etiology of this condition is also unknown. BRV has been linked to migraine and viral diseases. In a prospective study we collected the clinical history and the signs and results of neurotologic and audiologic tests from 33 patients with a BRV diagnosis. The clinical characteristics truly mimicked the vertigo seen in Menieres disease. The concept of vestibular Menieres disease is not widely accepted, and without auditory signs BRV is the only diagnosis that can be given to these patients. In other studies up to 25% of the patients initially diagnosed with BRV subsequently developed another peripheral vestibular disorder. Until the etiology of diseases involving vertigo is more clearly understood, artificial diagnoses like BRV, must be accepted.

The aim of the study was to evaluate the course of vestibular schwannoma (VS) when surgery was not attempted. The tumor may be slowly growing and surgery a risk for a patient. Twenty-eight patients out of 390 VS patients during years 1981-1995 were primarily recommended a non-surgical treatment. Another 3 patients refused the operation. Altogether 23 women and 8 men were evaluated. Their age varied from 30.6 to 74.6 years (median 56.7 years). Tumor size varied from 5 to 30 mm (median 15.0 mm) at the beginning of the follow-up. Patients symptoms, condition and other illnesses were recorded. Seven patients had neurofibromatosis 2 (3 of them had one hearing ear), 2 had severe mental problems, 5 patients had their only hearing ear and 11 patients were not recommended an operation because of their age and other illnesses. Patients were controlled with MRI at intervals from 1 to 3 years. The follow-up time varied from 1 to 20 years (median 2.0 years). The average tumor growth rate among unilateral VS patients was 0.035 cm/year and among bilateral tumors the average tumor growth rate was 0.015 cm/year. Two patients were later operated on, one 2 years after diagnosis because of the tumor growth and the other one 4 years after diagnosis-she had refused an operation earlier. Two patients could not be reached. Another patient had tumor growth but because of his illnesses he got a radiation beam instead of an operation. The majority of the patients could live fairly normal lives and required no treatment. Surgery is not the only alternative to VS patients. Wait-and-see policy is also a good alternative to those who have high operation risk or who refuse an operation.

Vestibular rehabilitation therapy (VRT) is used to enhance compensation after peripheral vestibular lesion. In visual feedback posturography (VFP) a patient can practice postural control actively on a force platform and progress in the VRT can be objectively measured. The aim of the study was to determine normative values for stability limits (SL) in the VFP. Eleven healthy subjects were measured with force platform in visual feedback condition. Subjects were instructed to move their center of gravity (COG) marker to given targets, which were displayed on a computer screen in front of them. Target distance from the center of the platform was increased step by step to determine the SL in 8 directions. Hit delays (HD) to the targets and hold percentages (HP) within the targets were measured to quantify the difficulty of the individual targets as a function of subject's shoe size. With fixed feet position the SL in anterior direction increased 1.2 times the absolute increase in shoe length. An almost similar increase was found in anterolateral direction. The knowledge of the mechanical SL is important, because targets near SL should be avoided for safety reasons.

In the head autorotation test (HART) gain is commonly used to determine the vestibulo-ocular reflex (VOR). The purpose of this work was to evaluate the relevance of phase (the phase difference between the eye and corresponding head movement) in describing the VOR. The phase was determined in 5 frequency bands in both degrees and milliseconds (ms) in 4 groups: 30 healthy adults, 15 elderly subjects, 37 vestibular schwannoma (VS) patients, and 35 Meniere's disease (MD) patients. In healthy adults and in MD patients the phase was close to nil in the frequency bands of 3 and 4 Hz. In elderly subjects phase lead was between 5.0 and 15.5 ms in each frequency band. Patients with VS showed a phase lag of -4.2 to -7.6 ms. The mean phase of the elderly in the frequency band of 3 Hz differed statistically significantly from that of MD and VS patients, and in the frequency band of 4 Hz from that of healthy adults and VS patients. In summary, the elderly had phase lead and VS patients showed increased phase lag in the frequency bands higher than 2 Hz. The phase is useful parameter together with gain in evaluating VOR and it seems to change in aged subjects and in patients with permanent vestibular lesion.

Artificial intelligence donates new possibilities to neurotologic research. Neural networks are a computer-based reasoning method which can be applied in expert systems created for clinical decision support. Neural networks have been used in medical imaging, in medical signal processing and to analyze both clinical and laboratory data. Principally, neural networks simulate the function of the brain. They have to be taught to make correct decisions from the input data. This learning process can be either supervised or unsupervised. The decision making is based on mathematical transformations and it occurs on a hidden level. Calculations are made on parallel manner and the decision making simulates pattern recognition method. Neural networks suit well in medical problems which cannot be defined in simple rules. A drawback of neural networks is that the decisions are irrational and cannot be motivated to the user. Another problem is neural networks' difficulty to handle incomplete input data, i.e., how to define some default or expected values for unknown input parameters. In a complex medical area, which would require multilayered neural networks, the neural networks require a large amount of solved cases for the learning process. In our experience neural networks seem not suitable for diagnosing vertigo and a better choice would be either case-based reasoning or possibly genetic algorithms or a combination of these.

Middle ear imaging constitutes a homogeneous test battery for evaluation of neurotological disease. The imaging comprises infra-sound fistula test, ABR, tympanoscopy, ECoG, and trans-promontiorial cochlear blood flow measurement. We used a fistula test with infra-sound loading on posturography. In tympanoscopy we used 5 degrees and 25 degrees endoscopes with a diameter of 1.9 mm and length of 125 mm. In blood flow measurement we used laser-Doppler system with a stainless steel tip placed on the basal turn against stira vascularis. The flux was analyzed with a computer with custom-made software. In ECoG, a silver ball electrode was placed on the round window. In 64 cases evaluated we were not able to verify a spontaneous PLF by tympanoscopy. Symptoms typical for spontaneous PLF with positive fistula test turned out to be caused by endolymphatic hydrops. Sudden deafness usually did not show reduced cochlear blood flow, but often an endolymphatic hydrops. Fistula test was positive in about 25% of cases with endolymphatic hydrops. Tympanoscopy caused very few complication. The procedure takes about one hour and is done ambulatorily.

We have examined the effect of intratympanic gentamicin on hearing and tinnitus in 69 patients with intractable Menière's disease. Tinnitus was scored from 1 to 4 depending on its severity. The mean pure tone audiometry level before treatment was 57.5 dB and 1 year after treatment 63.5 dB Five subjects became deaf in the treated ear, and in 13 subjects hearing loss was > 10 dB and in 21 subjects 0 10 dB. In 25 subjects significant improvement (> 10 dB) was gained, and in 5 patients. Tinnitus was significantly reduced after treatment with gentamicin. A total of 66 patients had tinnitus before treatment and tinnitus relief was rated as good. Four percent of the subjects had no tinnitus, 30% had slight tinnitus. 27% moderate tinnitus. 18% severe and 8% handicapping tinnitus.

We have developed an interactive database for vertigo than can be used to assist in the diagnostic procedure and to store the data in a form of a database. The database offers the possibility to split and reunite the collected information in a desired way. The database contains detailed information about patient history, symptoms and findings in neurotological, audiological and imaging tests. The symptoms are classified into three sets of questions: vertigo (including postural instability), hearing loss and tinnitus, and provoking factors. Confounding disorders are screened. The neurotological tests involve saccades, smooth pursuit, posturography and caloric test. In addition, findings in specified antibody testing, clinical neurotological tests. MRI, brain stem audiometry and electrocochleography are included. The input information can be applied in an expert system ONE for vertigo work-up. The database is user-friendly. Besides diagnostic purposes the database is excellent for research purposes, and combined with the expert system it works as a tutorial guide for medical students.

An otoneurological expert system (ONE) was developed to help collect data and diagnose the work-up of vertigo of both central and peripheral diseases causing vertigo. Patient history and otoneurological and other examination results are used in the reasoning process. The history is interactively collected and is complemented with clinical examination results. The case history data can be either mandatory or supportive. Mandatory questions are used to confirm a diagnosis, and conflicting answers are used to reject an unlikely disease. Supportive questions support or suppress a diagnosis, but their presence is not obligatory. The reasoning procedure of ONE scores every question independently for different diagnoses, depending on how well they agree with the symptom entity of a disease. Diagnostic criteria are set for each disease, in Meniere's disease, for example, the full triad is required. Graphic displays illustrate the linear and nonlinear correlation between the symptoms and diseases. For instance, both second-long Tumarkin-type attacks and attacks lasting hours give a high score while intermediately long attacks score much lower in Meniere's disease. To be able to take even rare diseases into consideration we try to diminish the possibility of a wrong decision rather than maximize the likelihood of reaching only one right decision.

We have been able to culture acoustic neuroma (AN) tissues by taking small tumor pieces during surgery from the cisternal or, preferably, metal part of the tumor where macroscopic tissue degeneration is not prominent. The AN pieces were transported in culture tubes to our cell laboratory where they were sliced and transferred to culture medium. The AN tissue demands a crude culture suspension containing laminin. We have been successful in culturing 15 successive ANs. The cells have different morphological features with characteristics of type Anthony A and B. Four main cell types were recognized: ameboid microglia-like cells, spindle-shaped cells, racket-shaped cells, and kite-shaped cells. However, no immortal cell line could be established. Some of the cultures were viable for up to 4 months.

We have developed a stimulation method where the subject is sitting and the head is rotated with shock bursts elicited by a shaker with a repetition rate of 2 Hz. The head movement is monitored with an accelerometer mounted on the cheek by a head band. The maximum amplitude of the head movement is 3 degrees. The electrodes were places on vertex with a negative electrode on the mastoid. During stimulation, 90 dB white noise was applied to the ears to mask the noise generated by the stimulus. We recorded following responses: i) VER from ipsilateral ear, ii) VER from contralateral ear, iii) eye movement with EOG, and iv) movement of the head. Amplification and averaging of the signal were made with an evoked response recorder (Nihon Kohden, Neuropac four). From 200 to 2,000 averaged responses were collected and stored for further analysis on a floppy disc. During second stage filtering the data were fed into a microcomputer where appropriate programs were used to eliminate the EMG and movement artifacts.

We investigated the effect of visual control on postural stability on a moving platform in 36 patients with Menière's disease (MD) in 25 patients with operated acoustic neurinoma (AN) and in 19 healthy controls. The force platform was placed on rails and oscillated linearly at frequencies from 0.2 to 5 Hz at a constant velocity of 30 mm/s. In all subjects, the support surface oscillation produced postural instability that differed significantly from the base line stability. The body sway velocity increased almost linearly with the increase of stimulation frequency. The MD patients swayed more than the AN patients at base line measurements in non-visual conditions but not during platform movement. In visual conditions the AN patients stabilized their posture significantly better than the MD patients, who showed deteriorating visual control of posture during platform movement. The controls differed from the patients in all test conditions except 5 Hz stimulation, which causes the body segment to fall into resonance. The Romberg quotients (RQ) in MD patients was significantly poorer during platform movement than in controls, except at 5 Hz stimulation. The AN patients had higher RQ values than controls, and mainly used vision to compensate their vestibular deficit. Thus, patients with MD fail to control their posture efficiently with vision during movement which may explain the visually induced dizziness in MD patients.

Since EOG signals are rather noisy, but magnetic coil signals almost noiseless, the latter type is a good reference to the former which is much easier to record. Concurrently recording magnetic coil and EOG signals we could verify some details as saccades which are often difficult to detect in noisy signals. It is important to recognise such phenomena in eye movement signals, because these affect the gain parameter computed between the vestibulo-ocular reflex signal and the head movement signal.

We studied predictive and pseudo random saccades in patients with cerebellopontine angle tumor. Target for the saccades was a laser beam which was reflected on the wall in front of the subject, and the stimulus was controlled by a computer. The fixed target was spaced at a distance of +/- 30 to each side of the subject. The random saccades jumped 20 degrees/40 degrees/60 degrees in an unpredictable manner. The saccade analysis program was based on pattern recognition. In the random saccade test none of the mean values of saccadic reaction time (SRT), saccadic accuracy (SA) and saccadic peak velocity (SPV) to the right or left differed significantly between the two groups. In the predictable saccade test there was statistically significant differences for certain variables: in right SRT (p < 0.01) and in left SRT (p < 0.01); in right SA (0.001 < p < 0.01) and in left SA (p < 0.001). The mean peak velocity (right SPV and left SPV) did not differ significantly between the two groups. When the stimulus is predictable, the saccades in a healthy subject are more timely spaced and accurate than in a patient. When the stimulus is unpredictable, "the memory of the past" has no importance and cannot help in saccade programming, and variability in the healthy subjects increases.

We examined the pseudo random smooth pursuit test in patients with cerebellopontine angle (CPA) tumors. Four different frequency combinations of sinusoids 0.15-0.35 Hz, 0.25-0.425 Hz, 0.3-0.7 Hz and 0.45-0.7 Hz were tested. Gain was calculated by comparing the smooth pursuit amplitude with stimulus after the supporting saccades had been removed. Phase was calculated by comparing maximum excursion of the eyes and stimulus. Gain was in the patients lower than in the controls in different frequency combinations, and the difference was statistically significant/highly significant in different frequency combinations. In the phase shift the differences were highly significant in the two higher frequency combinations and significant in the second frequency combination (0.25-0.425 Hz), while in the first frequency combination (0.15-0.35 Hz) the difference was not significant. The gain method was a somewhat better analyzing method than the phase shift method.

Symptoms and incidence of neuroborreliosis (NB) were studied in ambulatory patients visiting the ENT clinic in Helsinki. Especially we tried to search for possible markers indicating the connection between vestibular neuronitis and NB. A total of 350 patients were screened with the enzyme-linked immunosorbent assay (ELISA) technique for possible antibodies against Borrelia burgdorferi (BB). Twelve patients had positive serological reactions for BB with sera titer levels ranging from 640-14700 (normal < 500). In 2 additional cases, NB was clinically confirmed. In 7 cases a history of tick bite and in 4 cases erythema chronicum migrans was confirmed. In 9 cases, vertigo was the predominant symptom, and in 3 cases the symptoms were linked to facial nerve paresis. Six patients suffered from hearing loss. In 7 cases, the diagnosis was initially settled as vestibular neuronitis. NB seems to be present in about 4% of cases with apparent otologic diseases in Finland. In the majority of the cases, the disease resembles vestibular neuronitis in the acute stage. Since NB is tractable, all patients visiting the ENT clinic, especially those with vertigo, should be screened.

The effect of low frequency sound (LFS) on postural stability was studied in 55 healthy volunteers and in 50 patients with Menière's disease. The sound levels ranged from 130 to 132 dB and were given at frequencies of 25, 50 and 63 Hz. The patients with Menière's disease displayed increased body sway during stimulation. In the individual response, 26% of the patients with Menière's disease experienced significant body sway. The results demonstrate that subjects with Menière's disease are sensitive to low frequency sound. The activation of vestibulo-spinal responses by low frequency sound seems to be a result of the Tullio phenomenon, in which sound energy activates the vestibular end-organ.

The effect of linear perturbation at a frequency range of 8 to 24 Hz on postural stability was studied in 7 patients with unilateral vestibular function loss. Force platform technique was used with automatic analysis resulting in the sway velocity of the center point of force. In all patients the support surface movement produced increased sway velocity which was significantly greater than in the controls. Tests at lower frequencies (8 and 10 Hz) produced higher sway velocities than tests at higher frequencies (12, 14, 16 and 24 Hz). The results indicate that the vestibular system controls postural reflexes at a substantially higher frequency range than hitherto suggested.

The effect of instruction and repeatability of posturography measurement was studied in 24 healthy volunteers. In an instruction, "stable" (inverted pendular model) and "relaxed" (segmental oscillating model) positions were studied. In addition, the effect of habituation adaptation, and day-to-day variation were investigated. Sway velocity and average and maximum displacement during vibration perturbated stance were analysed. In individual responses, no statistically significant day-to-day variation could be observed and the individual variation was small. In the "relaxed" condition, the instability was greater when maximum displacement was analysed. No significant changes in sway velocity and average displacement were observed. The results demonstrated remarkable stability of normal postural control mechanism.

The postural control mechanisms were evaluated in 10 blinds and in 10 subjects with Usher's syndrome. The results were compared with 27 age matched healthy volunteers. In visual conditions the subjects with Usher's syndrome performed worse, but in nonvisual condition they performed equally well as the controls. The results were the same irrespective of whether the tests were performed on a rigid surface or foam rubber covered surface. The blinds and controls performed equally well on the bare surface, but the blinds performed significantly better on the foam rubber covered surface. The results indicate that in subjects with Usher's syndrome the vestibulo-cochlear degeneration is well compensated but the postural stability aggravated due to retinal degeneration. Blind subjects have a better postural control than their seeing referents, but the difference is only evident in situations in which the postural control is hampered by surface perturbation.

The effect of impulse noise on postural stability was evaluated in 54 subjects from the Finnish army, who were suffering from acute hearing loss caused by exposure to firearms noise. For referents we used 20 non-exposed army recruits and 39 civilian volunteers. The effects of vision, pressoreceptor function and proprioception were stepwise excluded or altered, leaving mainly the vestibular guidance of postural control intact. Since the postural perturbation was fairly smooth during these instances we assume that the condition evaluates mainly the function of the otolith organs in guiding stance. We found no difference in any of the test conditions used, between normal controls, army controls and impulse noise exposed subjects. Furthermore, there was no dose response with body sway and severity of hearing loss. The results indicate that impulse noise may not be the cause of significant functional changes in the vestibular system that can account for noise-induced postural instability.

Postural control is maintained by sensory feedback from visual, vestibular and somatosensory receptors. Recently several methods for evaluating postural control have been devised, utilizing an imposed perturbation. Most of these methods use stimuli which simultaneously affect more than one of the sensory feedback loops. In the present paper a posturographic technique is presented with specific loading of the proprioceptive system, using a computer controlled vibratory stimulus and computerized analysis of the results.

The effect of transdermally administered scopolamine (TTS scopolamine) (release rate 5 micrograms/h) and dimenhydrinate (100 mg) was examined on optovestibular nystagmus in 16 volunteers in a randomized double-blind trial. A statistically significant decrease in the optokinetic part of nystagmus was observed during all treatments. Most profound reduction was found during treatment with two TTS scopolamine. The vestibular part was reduced by treatment with two TTS scopolamine, only. The results indicate that scopolamine and dimenhydrinate exert their effect in motion sickness by reducing the vestibular and visual influx and by partly inhibiting the integrative functioning of the vestibular nuclei. In their action, the motion sickness drugs seem to assist the cerebellum by diminishing impulses from various orientation reflexes in order to preserve the functional capacity of the central nervous system. Different symptoms in motion sickness seem to arise when the vestibular gain operates beyond the normal range of the cerebellar control mechanisms.

A detailed analysis of risk factors in the development of sensory-neural hearing loss (SNHL) was carried out in 199 forest workers. The mean hearing threshold of both ears at 4000 Hz was measured and the effect of age, exposure, blood pressure, presence of vibration induced white finger (VWF), tobacco smoking and plasma lipid concentrations on SNHL were evaluated by multiple linear regression analysis. A part of aging the major risk factors were presence of VWF, elevation of LDL-cholesterol level and usage of antihypertensive agents. Additional factors in the analysis, e.g. smoking and diastolic and systolic blood pressure did not significantly contribute to the genesis of SNHL.

A computerized posturography system is composed of a custom made strain gauge force platform and it utilizes commercially available amplifiers. The body sway response signals are digitized for the calculation of the following parameters by a computer: average velocity of body sway, mean value for fore-aft and lateral body sway, and maximal amplitude of body sway. Calf muscles were exposed to vibration to disturb the postural control. The program contains appropriate filters to remove transient and quantification noise.

During recent decades a vast amount of literature concerning horizontal optokinetic nystagmus has emerged, regarding which--and especially as regards our own work--this report is intended to consider the clinical value of optokinetic nystagmus.

A review of the treatment of vestibular disorders with drugs is presented. In animal experiments, administration of certain drugs, e.g. alcohol, barbiturates and chlorpromazine, retards the vestibular compensation, while others, e.g. caffeine, amphetamine and ACTH, accelerate the compensation. In compensated animals, some drugs produce overcompensation and some decompensation. A double-blind, randomized trial of the effect of scopolamine and dimenhydrinate in patients with vertigo of varying origin showed, as compared with placebo, that these drugs did not significantly alleviate the vestibular imbalance. The reason for the poor efficacy of the treatment may have been overcompensation of vestibular function loss and adverse effects caused by the drugs. Care should be taken that the drugs used do not retard the vestibular compensation caused by the central nervous system.

In order to evaluate to what extent different diseases causing vertigo can be detected by studying vestibulo-spinal and vestibulo-ocular reflexes, 146 patients were examined. The diagnosis classes were: periodical attacks, position induced attacks, vestibular neuronitis, brain concussion, cerebrovascular disorders and acoustic neurinoma. Dynamic posturography was performed on all the patients, standard bithermal caloric test on 129 and voluntary saccades on 127 patients. The proportion of pathological test results in posturography exceeded that in the caloric test in all but one diagnosis class. In vestibular neuronitis the amount of abnormal test results was low in posturography, probably due to vestibular compensation. Posturography tested with eyes open and with 80 Hz vibration revealed disturbances in equilibrium the most sensitively.

Peak velocity of saccade, maximum velocity of smooth pursuit, and peak velocity of slow phase of vestibular and optovestibular nystagmus were measured three times daily on three separate days in 6 healthy subjects in order to estimate the intra-individual variation of the results of oculomotor tests. Analysis of variance revealed that the oculomotor performance of the individual subjects varied systematically, depending on whether the tests were performed in the morning, at noon, or late in the afternoon. In particular, the velocity of saccade displayed lowest values in the afternoon. The present results indicate that oculomotor performance may depend on the individual biological rhythm of fatigue; however, it is also possible that eye motor behaviour is coupled to an independent rhythm of motor activity. Circadian rhythmicity of oculomotor performance should be considered in follow-up studies and in examination of patients with reduced vigilance.