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Biomedical subjects

I Pyykkö

Publications and source records attributed to I Pyykkö.

At least 19 recordsLinked to original sources
PubMed1995

Abrupt unilateral deafness modifies function of human auditory pathways.

We studied nine patients with unilateral abrupt deafness caused by acoustic neuroma surgery. Cortical responses to tones delivered to the intact ear were recorded postoperatively with a 122-channel whole-scalp neuromagnetometer. In three patients, followed for 12 months with 2-4 measurements, evoked responses originating in the auditory cortices were weak and delayed one month after the operation in both hemispheres. During the follow-up, the amplitudes reached the control level. No response abnormalities were found in patients who were studied 1.5-4.5 years after the operation. Our findings suggest that abrupt unilateral deafness causes immediate changes in the function of auditory pathways of adult humans and that reorganization takes place within 1 year.

Adolescent↗
PubMed1995

Prognosis of falls among elderly nursing home residents.

The survival rate of 207 nursing home residents who fell during a two-month study period was followed for 12 months and compared with that of 94 residents of the same nursing home who did not fall during the same period. One year after the fall, 74 fallers and 13 controls had died. In the group of fallers, the main factors associated with mortality were male gender, dementia, Parkinsonism, the use of antidepressants, diuretics and vasodilators. Among the controls, the main factors associated with mortality were Parkinsonism, diabetes and the use of diuretics. Thirty-eight fallers (33 women and 5 men) and one (female) control suffered a fracture; 32 of them required hospital attention, and 15 (47%) died during the same hospital stay. These results indicate that falls are an ominous sign, particularly if the subject has dementia, depression or Parkinsonism, or uses diuretics. The male subjects in this study had a lower injury rate than females, but their mortality rate was higher. In terms of prevention, the major concern should be the effective treatment of depression and Parkinsonism. Withdrawal of diuretics, when possible, may have an effect on mortality. Physical training and other stimulating activities should be beneficial, but subjects with severe dementia seem to be beyond this kind of prevention.

Accidental Falls↗
PubMed1995

Database for vertigo.

An interactive database has been developed to assist the diagnostic procedure for vertigo and to store the data. The database offers a possibility to split and reunite the collected information when needed. It contains detailed information about a patient's history, symptoms, and findings in otoneurologic, audiologic, and imaging tests. The symptoms are classified into sets of questions on vertigo (including postural instability), hearing loss and tinnitus, and provoking factors. Confounding disorders are screened. The otoneurologic tests involve saccades, smooth pursuit, posturography, and a caloric test. In addition, findings from specific antibody tests, clinical neurotologic tests, magnetic resonance imaging, brain stem audiometry, and electrocochleography are included. The input information can be applied to workups for vertigo in an expert system called ONE. The database assists its user in that the input of information is easy. If not only can be used for diagnostic purposes but is also beneficial for research, and in combination with the expert system, it provides a tutorial guide for medical students.

Anxiety↗
PubMed1995

Presymptomatic DNA and MRI diagnosis of neurofibromatosis 2 with mild clinical course in an extended pedigree.

Neurofibromatosis 2 (NF2), a dominantly inherited disorder, typically manifests as bilateral vestibular schwannomas and predisposes to other nervous system tumors. In this study, we present a large pedigree with a benign course of NF2 (mild Gardner type) characterized by slowly growing vestibular schwannomas but few other manifestations. The family was thoroughly investigated with neurologic, ophthalmologic, and neuro-otologic methods including gadolinium-enhanced MRI of the head and spine and DNA linkage analysis. In the clinical analysis of 22 family members, MRI was superior to neuro-otologic methods in the detection of asymptomatic tumors. Based on the DNA linkage analyses we identified the NF2 mutation carriers with a high degree of certainty. These DNA markers (CRYB2, NEFH, D22S268, and D22S280) can also be used for presymptomatic diagnosis in other NF2 families. Early detection of NF2 gene mutation carriers has become possible using linkage analysis in familial NF2. MRI screening of carriers will reveal presymptomatic vestibular schwannomas (and other CNS tumors), making early intervention possible, but an efficient treatment strategy to prevent deafness has not yet been established.

Adult↗
PubMed1995

Cochlear vascular pathology and hydrops in otosclerosis.

Three ears with otosclerosis were found incidentally in a series of human temporal bones examined to evaluate cochlear sensorineural degeneration. Otosclerosis was identified with microdissection, surface preparation technique and transmission electron microscopy. Vascular abnormalities were present in all ears, and otosclerosis involved the cochlear endosteum extensively, mainly in the scala tympani of the basal turn. In the scala tympani of the lower half of the basal turn, shunts had formed so that venules deviated abruptly from their normal radiating course towards the spiral vein, left the scala and entered into otosclerotic foci. There was a marked loss of radiating venules in areas where otosclerosis affected the endosteum of the scala. In the pair of bones capillaries in the stria vascularis were extremely dilated, the widest being 80 microns in diameter. The third single bone from a patient with Meniere's disease had severe cochleo-saccular hydrops. Ten serially sectioned temporal bones with known otosclerosis were reviewed. Two of the bones, one of which had cochleo-saccular hydrops, displayed vascular shunts in the scala tympani and enormously dilated strial capillaries with a maximum diameter of 139 microns.

Adult↗
PubMed1994

Intratympanic gentamicin in bilateral Menière's disease.

Treatment of bilateral Menière's disease is a delicate task. Streptomycin has demonstrated its ability to successfully control the vertigo attacks, but in some cases it results in oscillopsia and transforms the periodic attacks to permanent instability. If the site of the active labyrinth can be determined, a more specific treatment can be tried. We have treated 14 patients with intractable bilateral Menière's disease with intratympanic gentamicin (Garamycin, 40 mg/ml) administered initially in either 1, 2, 3, or 4 injections. The patients were tested at frequent intervals and followed up for 2 years. The work capacity, severity of vertigo, and gait difficulties were scored before treatment and during each test occasion. The postural stability was evaluated on a force platform and sway velocity was analyzed. Before treatment, moderate or severe reduction of work capacity was experienced by all of the subjects, which correlated to severity of vertigo and gait problems. Two years after treatment, the vertigo attacks were eliminated in 11 subjects and controlled in three subjects. The work capacity of three subjects was still moderately or severely reduced. This reduction depended on gait disturbance and Tumarkin attacks. The average postural stability returned to pretreatment level 2 years after the treatment was begun. The outcome of the caloric responses did not correlate with the outcome of the treatment. Hearing was not significantly affected by the treatment. Intratympanic gentamicin treatment is a relatively safe and effective way to treat bilateral Meniere's disease when the symptoms can be localized to one ear.

Adolescent↗
PubMed1994

Recovery of the sutured facial nerve after removal of acoustic neuroma in patients with neurofibromatosis-2.

The authors compared the long-term recovery of sutured facial nerves after the removal of 8 neurofibromatosis-2 (NF2)-associated and 22 non-NF2 acoustic neuromas. The patients were from a series of 270 patients operated on for an acoustic neuroma between 1979 and 1989. The assessment was done with a modified House and Brackmann scale from video recordings. At least some facial movement or tone was achieved (Grade 5 or better) in all but three patients, but in none was the recovery excellent. The facial function, judged by the overall appearance in movement, recovered less in patients with NF2 (P = 0.048); a moderately good recovery (Grade 3 or better) was seen in one patient of eight with NF2, as compared with 13 of 22 with non-NF2. In conclusion, if the tumor cannot be peeled off easily from the facial nerve in patients with NF2, leaving a fragment of tumor behind is preferable to cutting and suturing the facial nerve.

Adolescent↗
PubMed1994

Interface between the facial nerve and large acoustic neurinomas. Immunohistochemical study of the cleavage plane in NF2 and non-NF2 cases.

In acoustic neurinoma surgery, the surgeon is required to find a cleavage plane between the facial nerve and the tumor, and with the aid of the operating microscope this is usually achieved by fine dissection. A histological specimen of the nerve-tumor interface is available only if the facial nerve was hopelessly adherent to the tumor (usually a large or giant neoplasm) and the surgeon decided to sever the nerve to obtain a complete removal. The authors have examined immunohistochemically the nerve-tumor interface of 20 such facial nerves (six cases of neurofibromatosis 2 (NF2) and 14 of non-NF2) in a series of 351 acoustic neurinomas. The largest extrameatal dimension of the 20 tumors ranged from 20 to 51 mm (median 39 mm). In all of these 20 instances the nerve-tumor contact area was at least partially devoid of a clear-cut histological cleavage plane. Where the facial nerve trunk was attached to the surface of the tumor, nerve fibers of the contact areas either abutted directly against tumor cells or nerve fibers were seen to penetrate into the tumor tissue. Frank embedding of nerve fibers was more frequent in NF2.

Adult↗
PubMed1994

Effect of hand-arm vibration on inner ear and cardiac functions in man.

To evaluate distant effects of hand-arm vibration we studied Finnish forestry workers using chain saw during the years 1972 through 1990. The hearing was tested annually and individual regression curves for sensorineural hearing loss (SHL) were calculated. Robinson's model was used in prediction of SHL. The heart rate variation (HRV) indexes at rest and during deep breathing test were analyzed to measure autonomic nervous function. In Robinson's model the measured SHL (17.8 dB) respected the predicted SHL (17.2 dB). The subjects with VWF had on average, 10 dB greater hearing loss than those who did not have VWF. The regression model based increase of hearing loss during follow up correlated with ageing, not to VWF. The intercept differed significantly in those with VWF from those without VWF. We found a significant difference between HRV indexes during deep breathing test in those with the shortest and those with the longest vibration exposure. The HRV decreased with age, but multiple regression analysis showed that the total exposure time to vibration had an independent negative association with HRV indexes. Our results suggest that prolonged exposure to vibration caused by chain saw has negative effects an autonomic functions. The aggravated hearing loss in subjects with VWF may be due to vibration induced changes in the autonomic nervous system or internal factors of the blood vessels.

Arm↗
PubMed1994

Vibration exposure and prevention in Finland.

The number of annually compensated occupational diseases due to exposure to hand-arm vibration (HAV) has decreased during the last 15 years. The number of exposed workers has been declining in Finland, especially in forestry work, as harvesters have increasingly replaced manual chain saw operations. During the entire 1970s, forest work caused more cases of vibration-induced occupational diseases than all industrial branches together. The decrease is mainly due to the technical development of chain saws, but also to the effective health care services in Finland. Other factors such as warm transport, warm rest cabins in which to take pauses at work, warm meals, adequate protective clothing, and vocationally adjusted early medical rehabilitation have helped to cut down health hazards, especially in forest work. The number of new cases has been decreasing in Finland not only in forestry but also in other industries. In Finland a considerable amount of research has been conducted to hand-arm vibration, resulting in the increased awareness of the health risks related to certain occupations. This has helped to carry out the Primary Health Care Act (1972) followed by the Occupational Health Care Act (1979) which obligates employers to arrange occupational health care for their employees. We believe that the research activity has contributed significantly to achieving the present health in Finnish work places. The purpose of the present paper is to describe the cases of occupational exposure to HAV, and the effectiveness of different preventive measures in Finland.

Finland↗
PubMed1993

Vibration stimulus induced EEG bursts in isoflurane anaesthesia.

The EEG and heart rate reactions to vibration stimulus were studied in 14 patients during moderately deep surgical isoflurane anaesthesia, at a level when EEG showed a burst suppression pattern. Vibration applied to the palm of the hand induced bursts in EEG in 12 patients, usually with a latency of about 0.5 sec from the onset, or from the end of the 3 sec stimulus. Increases in heart rate were seen at bursts related to both vibration onset and offset, as well as at spontaneous bursts. With spontaneous bursts, an initial positive wave was frequently seen. In 6 patients the vibration induced bursts were different in shape from the spontaneous bursts; no initial positive wave was seen before the negative DC shift in Cz-Fz recording. We conclude that EEG bursts can be evoked by a non-noxious stimulus such as vibration in patients during isoflurane anaesthesia.

Adult↗
PubMed1993

Evaluation of postural stability by computerised posturography following outpatient paediatric anaesthesia. Comparison of propofol/alfentanil/N2O anaesthesia with thiopentone/halothane/N2O anaesthesia.

Simple clinical tests, like Romberg's test or a walking test, have proved to be inadequate guidelines for safe discharge after outpatient anaesthesia. A randomised study was therefore planned to compare postural stability measured by computerised posturography in 31 oral midazolam-atropine premedicated children aged 6.9 (s.e. 0.4) years who had been anaesthetised with either propofol/alfentanil/N2O or thiopentone/halothane/N2O. The sway velocity of the children was measured before premedication and 1, 2 and 3 h after the end of anaesthesia. Results show that sway velocity had returned to baseline values 3 h after the end of anaesthesia in all children who had received propofol/alfentanil/N2O and in 12 of the 15 children who had received thiopentone/halothane/N2O. The quantified version of the Romberg test performed with eyes open or closed was not impaired after anaesthesia, compared with the control values, indicating that in children poor equilibrium is not compensated by vision. The clinical recovery with respect to the times to eye opening, to responding to command or to being fully awake did not differ between the two anaesthesia methods. On the basis of recovery assessed by postural stability, propofol/alfentanil/N2O anaesthesia was not preferable to thiopentone/halothane/N2O anaesthesia after minor paediatric otolaryngological surgery.

Alfentanil↗
PubMed1993

Human spumaretrovirus in the etiology of sudden hearing loss.

The etiology of sudden sensorineural hearing loss, so called sudden deafness, has for long puzzled researchers. Recently we have studied the possibility that a hitherto relatively unknown retrovirus group consisting of human spumaretroviridae (HSRV) might be the causative agent of sudden deafness. During the last 3 months we have screened about 30 cases of sudden deafness. In 4 of them antibodies against HSRV were detected. Three of them had suffered from a flu-like condition about 2 weeks before the onset of hearing loss. In 2 cases the hearing of both ears was involved, in 1 case a relapsing hearing loss was observed, and 1 case developed a Meniere-like symptomatology with a fluctuant hearing loss. Vertigo was present in 3 patients and all suffered from tinnitus. Full recovery of hearing was observed in 4 of 6 affected ears whereas 2 ears became practically deaf with poor speech discrimination. At present it seems likely that a significant part of sudden deafness is caused by HSRV infection. The course of infection follows the spontaneous course of sudden deafness described by many authors. We encourage otologic units to screen for HSRV when assessing the etiology of sudden deafness.

Adult↗
PubMed1993

Hearing loss risk from exposure to shooting impulses in workers exposed to occupational noise.

The effect of shooting impulses on hearing was analysed in 150 professional forest workers exposed to noise from chain saws. The exposure to shooting impulses (Lesi) was designed to take into account the peak levels of shooting impulses, their number and use of hearing protectors. Hearing loss was dependent on Lesi even after allowing for the age of subjects and their exposure to chain saw noise. Hearing threshold levels were compared between pairwise matched groups with high and low Lesi. Proper matching was achieved for age, chain saw noise, salicylate consumption, blood pressure, cholesterol, smoking and vibration-induced white finger symptoms. The workers with high Lesi had 9 dB greater hearing loss at 4 kHz and 10 dB greater hearing loss at 8 kHz than those with low Lesi, the difference being significant at P < 0.05 level. In evaluation of noise-induced hearing loss the exposure to shooting impulses from different calibre weapons should be determined since they increase the extent of hearing loss. The present study describes the Lesi method which more accurately evaluates the harmful effects of shooting noise impulses on hearing.

Adult↗
PubMed1993

A measurement system of head movements for the vestibulo-ocular reflex.

This paper describes an efficient technique to record head movement signals for the computer analysis of vestibulo-ocular reflex. The technique has essentially lower costs than the method of rotatory chair. It is easy to operate and yields recordings of high quality. The system is connected to our analysis program of vestibulo-ocular reflex, the results of which are briefly presented.

Costs and Cost Analysis↗
PubMed1992

Vibration syndrome among Finnish forest workers between 1972 and 1990.

A longitudinal study on vibration syndrome among professional forest workers was carried out in Finland from 1972 to 1990. In the course of the follow-up the weighted vibration acceleration of chain saws decreased from about 14 to 2 m/s2. The prevalence of vibration-induced white finger (VWF) decreased gradually from 40% to 5%. Numbness occurred mainly at night, and its prevalence decreased from 78% to 28%. During part of the follow-up period (1975-1990) the complaints of hand muscle weakness decreased from 19% to 9%. Disorders of the musculoskeletal system were considered to cause more disability than VWF. The decreased vibration acceleration and the lighter weight of chain saws were considered the main reasons for the decrease in the prevalence of vibration-induced symptoms.

Adult↗
PubMed1992

On identification of saccades from sinusoidal eye movement signals.

Sinusoidal eye movements and potential saccadic eye movements are examined using the syntactic pattern recognition method presented previously. A few computer tests are presented for the verification of potential saccades from signals of sinusoidal eye movements. The technique was developed and tested with electro-oculographic signals. The verification of saccades consists of three tests: the estimation of average noise peaks in an eye movement signal; an angular velocity threshold; and the comparison between a sinusoidal eye movement signal and the corresponding stimulus signal. The technique is also efficient for noisy signals of eye movements, which were stimulated by both predictive and non-predictive sinusoidal stimulus movements.

Calibration↗