Biomedical subjects

I Pyykkö

Publications and source records attributed to I Pyykkö.

At least 19 recordsLinked to original sources

PubMed2006

Value of imaging studies in vertiginous children.

OBJECTIVE: Imaging of the head is expensive and can be stressful for children, some of whom need anesthesia for the procedure. The aim of this study was to determine which vertiginous children benefit most from head imaging. METHODS: We conducted a retrospective chart review of all children aged under 18 years who were referred to the Helsinki University Children's Hospital Radiology Department (tertiary referral center) for head computerized tomography (CT) or magnetic resonance imaging (MRI) over a 1-year period. We analyzed and reviewed the medical records of 87 children who had undergone imaging of the head due to vertigo. RESULTS: Altogether 978 children underwent imaging of the head for various indications. Of these, 87 aged 0-16 years (mean age 8 years) were imaged because of vertigo. Abnormalities were seen in the images of 37 children; 23 were new findings and 14 showed no change in comparison to earlier deviant images. The most common abnormalities in head imaging were brain tumors, infections, multiple sclerosis lesions, and other lesions in T2-weighted images. Of the 23 vertiginous children with a new finding, 19 also had neurological deficits. While four children had no neurological symptoms, three had intense headaches. CONCLUSIONS: Head imaging is necessary for vertiginous children with neurological deficits or persistent headaches or who have sustained a head trauma. If vertigo is the only symptom without trauma, imaging studies will not aid diagnostic work-up.

Adolescent↗

PubMed2004

Postural instability in Meniere's disease.

In order to characterize the postural instability by duration of Meniere's disease (MD) we present the results of 180 MD patients tested on posturography. The duration of the disease varied from 4 weeks to 36 years. The patients were clinically examined and they had filled a questionnaire concerning their symptoms. Postural instability was examined by a force platform posturography and the results are expressed as sway velocities (SV). There was no statistically significant difference in the mean SV between groups of different duration of MD. The number of the patients with normal eyes open SV declined by duration of the illness from 73% to 38% but the decline was not statistically significant. The mean age in the different duration groups of MD varied from 47 to 61 years. In general 58% of the patients had their eyes open SV in normal range and 55% when measured eyes closed. When examining the SV between the 4 different hearing stages of MD we found that those belonging into the group III (pure tone average [PTA] 41-70 dB) had significantly higher eyes open and eyes closed SV's than the patients in the group I (PTA under 25 dB).

Adult↗

PubMed2003

Can low frequency sound stimulation during posturography help diagnosing possible perilymphatic fistula in patients with sensorineural hearing loss and/or vertigo?

Perilymphatic fistula (PLF) is often difficult to diagnose because of the similar symptomatology, such as vertigo, tinnitus and hearing loss, which is found in several inner ear diseases. We attempted to correlate a positive result of low frequency sound (LFS) stimulation tests in posturography with the presence or absence of a PLF confirmed by transtympanic endoscopy in 209 patients with various inner ear diseases (Meniere's disease ( n=128), vestibulopathy ( n=41), cochleopathy ( n=28) and sudden deafness ( n=12). LFS provoked unsteadiness in posturography without PLF in 24 patients with Meniere's disease, in 5 patients with vestibulopathy, in 3 patients with cochleopathy and in 2 patients with sudden deafness. In one patient, tympanoscopy revealed fistula in the round window membrane that was covered with a fibrinous layer. In four cases there was abnormal light reflex in the round window but without PLF. In eight cases, Hennebert's sign was present with nystagmus, without PLF. We conclude that pathological responses to the LFS test in posturography can also be encountered in other inner ear diseases without PLF.

Acoustic Impedance Tests↗

PubMed2002

Hearing loss and tinnitus in Meniere's disease.

OBJECTIVES: To characterize hearing loss, tinnitus and associative factors in Meniere's disease. METHODS: From our vertigo database consisting of 1356 patients, we retrieved 243 patients with Meniere's disease (MD). RESULTS: Hearing loss was the initial symptom in 13% of cases. Altogether 64% (n=133) of the patients stated that their hearing was reduced during the vertigo attack. The hearing deteriorated more likely during the vertigo attack if the vertigo attack was very intense [r(206)=0.19]. Tinnitus was the initial symptom in 5% of cases. The tinnitus was mild in 38% (n=90), moderate in 32% (n=76) and severe in 30% (n=72) of patients. The intensity of tinnitus correlated with the occurrence of drop attacks [r(237)=0.29], vertigo provoked by head positioning [r(235)=0.25], by physical activity [r(230)=0.33], or by pressure changes [r(239)=0.27]. CONCLUSION: Prolonged disease causes deterioration of hearing. Intense tinnitus is common in MD and is more often seen in late stage of the disease.

Adolescent↗

PubMed2001

Clinical picture of vestibular schwannoma.

PURPOSE: To characterize the clinical picture with vestibular schwannoma, we retrieved 122 patients with vestibular schwannoma from the vestibular unit of the Helsinki University Central Hospital. PROCEDURES: The patients filled out a questionnaire concerning their symptoms, earlier diseases, accidents, and the use of tobacco and alcohol. This information was then completed with results of audiometric, neurotologic and imaging studies. The data were prospectively stored to the database of neurotologic expert system called ONE. RESULTS: The average tumor size was 21 mm. Most of the patients had hearing loss (94%) and tinnitus (83%) but only half of them (49%) had vertigo attacks. The most common initial symptom was hearing loss combined with tinnitus (34%, n=44). Vertigo only was the initial symptom for 12 patients. The mean duration of a vertigo attack was from 5 min to 4 h and the intensity of the attack was regularly mild (37%) or moderate (32%). The vertigo of the vestibular schwannoma patients differed from vertigo in other diseases by the absence (63%) or low intensity (18%) of nausea. Spontaneous nystagmus was present in 56 patients (46%), and caloric asymmetry (>25%) was observed in 66% (n=69). Caloric asymmetry increased with tumor size. The prevalence of headache was 18% (n=21). Sudden slips seldom (7%) occurred. CONCLUSION: Hearing loss and tinnitus are the main symptoms of vestibular schwannoma. Only half of patients have vertigo. Screening to detect vestibular schwannoma is more yielding in sudden deafness patients rather than in patients with Meniere's disease.

Caloric Tests↗

PubMed2001

Evaluating training data suitability for decision tree induction.

Decision tree induction, as well as other inductive learning methods, requires training data of high quality to be able to generate accurate and reliable classification models. Example cases should form a representative sample from the application area, and the attributes used to describe example cases should be relevant and adequate for the classification task to be solved. In this paper, measures of the strength of association and an entropy-based approach have been used to assess the quality of the training data. Studied classification tasks related to three otological data sets: a conscript data set, a vertigo data set, and a postoperative nausea and vomiting data set. The paper suggests that the studied approaches give some guidelines about the quality of the training data, but other approaches are also needed to guide training data building.

Adolescent↗

PubMed2001

Causes of persistent postoperative headache after surgery for vestibular schwannoma.

Our aim was to elucidate the aetiology of persistent postoperative headache, a common sequel for several years after vestibular schwannoma surgery through the retrosigmoid approach. Twenty-seven patients with reported major postoperative headache were tested for vestibular responses and cervico-collic reflexes. The role of local anaesthesia injected into the neck muscle insertions or around the occipital nerves was evaluated. Sixteen patients operated on for vestibular schwannoma, but without headache, and 12 healthy volunteers served as control groups. Vestibular responses and cervico-collic reflexes deteriorated equally in the patients regardless of whether or not they had a postoperative headache. Local anaesthesia did not alter the results. The posturography results were increased among both patient groups. Sumatriptan alleviated pain in nine patients and abolished it completely in one out of these nine patients. Vestibular imbalance or abnormal activation of neck muscles do not explain postoperative headache. Occipital nerve entrapment or neuralgia explains the headache in a few patients. The relatively pronounced sumatriptan effect may, however, suggest a trigeminal nerve mediated cause for postoperative headache.

Adult↗

PubMed2001

Short-lasting drop attacks in Meniere's disease.

OBJECTIVES: To study the vertigo attacks known as Tumarkin attacks or drop attacks (DA). DA are characterized by sudden loss of balance with or without falls but with preserved consciousness, and they are supposedly triggered by changes in the otolith function of Meniere's disease (MD). STUDY DESIGN AND SETTING: Data from 243 consecutive MD patients were collected into a database of an otoneurologic expert system. RESULTS: DA was experienced by 72% (n = 173) of the patients with MD. It correlated with visually provoked vertigo. Gait difficulties, tinnitus, and anxiety were more common in the DA group. Long lasting vertigo attacks were more frequently provoked in the DA subjects by physical strain (58% vs 14%), head movements or changes in head position (71% vs 48%), pressure changes (54% vs 12%), or rapid movements in visual surroundings (65% vs 35%) than in the non-DA subjects. CONCLUSION: DA are common in MD patients. The abrupt occurrence of DA make them poorly tolerated. SIGNIFICANCE: DA are more common in advanced MD.

Accidental Falls↗

PubMed2001

Sensorineural hearing loss after vibration: an animal model for evaluating prevention and treatment of inner ear hearing loss.

Sensorineural hearing loss following a variety of acoustic trauma, including middle ear surgery, is well known. Current literature, which points to the deleterious influence of noise on the inner ear during surgery, has yet to assess the influence of vibration generated by the burr. The purpose of the study reported here was to establish an animal model that mimics drilling and can be used to explore methods of hearing loss prevention and treatment. A specially developed electromagnetic vibrator was calibrated and used in 59 guinea pigs to induce hearing loss. Both young and old guinea pigs were used. The bony external ear canal of guinea pigs were exposed to vibration or sound of varying duration and intensity. The vibration of the temporal bone and noise level in the middle ear were measured. Electrocochleography was recorded to evaluate the hearing loss. Among the young animals, 90% developed a significant threshold shift (TS > 20 dB), when vibrated with 250 Hz at an intensity of 6.2 m/s2 for 15 min. An average of 42 dB TS was observed. With 10 min exposure 63% showed a TS. The older animals vibrated for 5 min developed the same TS (mean TS 34 dB) as the young animals when vibrated for 10 min. The vibration-induced TS showed no recovery within 3 days of observation. In the contralateral ear 4 out of 5 animals showed TS > 20 dB. When exposed to sound levels exceeding the vibration-generated sound in the middle ear (119 dB at 250 Hz) only 2 out of II animals (18%) showed TS. The frequency of TS and level of TS were significantly greater in the vibrated animals than in sound-only exposed animals (p < 0.01). The degree of vibration-induced TS in the present animal model could be controlled by vibration intensity and duration. The older animals were more susceptible to vibration-induced inner-ear damage than younger animals. This model will be used in further studies to find methods for prevention and treatment of hearing loss during ear surgery.

Animals↗

PubMed2001

Classification of patients on the basis of otoneurological data by using Kohonen networks.

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.

Algorithms↗

PubMed2001

Autosomal dominant midfrequency hearing impairment.

At present, 48 different gene loci have been localised and nine gene mutations have been characterised for non-syndromic hearing impairment. We have identified a large five-generation family with mid-and high-frequency hearing impairment. Family members were considered to be affected only if they had bilateral sensorineural hearing loss below the 90th percentile of an age and sex-dependent control audiometric curve of ISO class B. The inheritance of hearing impairment was autosomal dominant. Of seven affected individuals, six were females and one was male. The hearing loss among affected family members was bilateral, sensorineural and varies from mild to moderate. The type of audiogram was U-shaped. Genetic linkage studies are in progress and our preliminary data show exclusion in chromosome 6, chromosome 11 and chromosome 19 in already known loci for midfrequency hearing impairment. This means, we are mapping a novel locus for autosomal dominant midfrequency hearing impairment.

Audiometry, Pure-Tone↗

PubMed2001

Application of artificial intelligence in audiology.

In this paper, machine learning methods based on artificial intelligence theory are applied to the computer-aided decision making of some otoneurological diseases, for example Ménière's disease. Three methods explored are decision trees, genetic algorithms and neural networks. By using such a machine learning method, the decision-making program is trained with a representative training set of cases and tested with another set. The machine learning methods are useful also for our otoneurological expert system, One, which is based on a pattern recognition approach. The methods are able to differentiate most of the cases tested between the six diseases included, provided that a sufficiently large training set is available.

Algorithms↗

PubMed2001

Using decision tree induction to model oculomotor data.

Decision tree induction is a machine learning method used to generate classification models from data sets. Numerous decision trees were constructed to examine relationships between oculomotor test parameters and lesion sites in a data set containing cases with operated cerebello-pontine angle tumour, operated hemangioblastoma, infarction of cerebello-brainstem and Ménière's disease, and control subjects. The aim was to find useful parameter combinations with discriminatory power. Decision trees constructed using both pursuit eye movements and saccadic eye movements yielded the best classification results. This is reasonable: oculomotor test results vary according to the site of the lesion and so the performance ability of subjects has to be taken into account in the classification. The decision tree program was able to generate classification models from the oculomotor data set. Generated decision trees were intelligible and can be utilized in physicians' research work.

Decision Making↗

PubMed2001

Age and noise-induced hearing loss.

The purpose of the study was to evaluate the effect of noise, age and confounders in noise-induced hearing loss (NIHL). Information about work exposure, the use of hearing protective devices, audiogram, environmental and biological factors was collected from 406 paper mill workers exposed to noise levels of 91-94 dB(A), 124 forest workers exposed to noise levels of 96-99 dB(A) and 176 shipyard workers exposed to noise levels 95-97 dB(A). In addition to noise exposure, we collected the following confounders: smoking habits, serum cholesterol, systolic or diastolic blood pressure and use of analgesics. Subjects were classified based on median values, into high- and low-risk groups. The confounders were a significant source of hearing loss (HL) in younger and elderly groups of subjects, serum cholesterol level being the most important. In risk analysis the confounders partly masked the effects of noise in the development of HL. For subjects with less than two confounders, occupational noise exposure determined the development of NIHL. As the number of confounders increased, the noise exposure was overruled by these factors in the development of HL. In analysis where the subjects were matched with pairs by age, exposure, blood pressure and serum cholesterol level, the elderly subjects were more susceptible to NIHL than younger subjects. Factors independently but causally related to age were important in the development of NIHL among workers exposed to noise levels below 98 dB(A).

Adult↗

PubMed2001

Effects of peak levels and number of impulses to hearing among forge hammering workers.

The purpose of the study was to (1) compare measured and estimated hearing loss among forge hammering workers by applying models for risk assessment based on measurements of impulse noise, and (2) model the hazardous effects of impulse noise on hearing. Noise exposure and hearing loss among forge hammering workers were studied at two forge workshops of an automobile company, where the equivalent sound pressure levels (104 and 105 dB) were the same, but the peak levels and degree of impulsiveness were significantly different. The hearing threshold levels of selected groups of workers (97 and 235 workers) were determined. Comparison between the measured and expected hearing losses defined according to the ISO standard revealed 2 dB difference in excessive hearing loss (1 dB and 3 dB for the workers of workshop 1 and 2, respectively). The excessive hearing loss equals an increase of 3.5 years of exposure. The hearing loss of workers exposed to low impulsive noise could be predicted well using ISO 1999-1990. The hearing loss of workers exposed to high impulsive noise correlated significantly with the peak levels and the number of impulses in combination.

Adult↗

PubMed2001

Basic fibroblast growth factor in nasal polyps immunohistochemical and quantitative findings.

Basic fibroblast growth factor (bFGF) is a mediator with potent mitogenic properties. Increased amounts of this mediator have been demonstrated in damaged lung tissue, and it has been suggested to increase the healing of gastro-duodenal ulcers. In order to quantify the amounts and document the localization of bFGF in nasal polyps, polyp tissue from 12 patients undergoing polypectomy was analyzed by ELISA and immunohistochemistry. Mucosa from the inferior turbinate was analyzed in the same manner for comparison. The amount of bFGF detected in polyp tissue was significantly higher than that in turbinate mucosa. The amount of bFGF was also significantly higher in the group of patients with high degree of inflammation. The immunohistochemical findings demonstrated abundant bFGF activity mainly in the glandular acini, in the epithelium, in infiltrating inflammatory cells and in the vessel walls. We propose that bFGF may contribute in a significant way to the formation of nasal polyps.

Aged↗

PubMed2001

On classification capability of neural networks: a case study with otoneurological data.

We investigated the capability of multilayer perceptron neural networks and Kohonen neural networks to recognize difficult otoneurological diseases from each other. We found that they are efficient methods, but the distribution of a learning set should be rather uniform. Also it is important that the number of learning cases is sufficient. If the two mentioned conditions are satisfied, these neural networks are similarly efficient as some other machine learning methods. The conditions are known in the theory of neural networks [1,2], but not often taken seriously in practice. Both networks functioned as well, excluding the case with several input variables, where the Kohonen neural networks surpassed the perceptron.

Algorithms↗

PubMed2001

Towards virtual reality stimulation in force platform posturography.

We developed a stimulation technique on the basis of virtual reality methods for balance investigation performed in balance laboratories of otorhinolaryngological clinics and institutes of occupational health. Such a stimulation technique is greatly progressive in the sense that by creating virtual moving views and "virtual worlds" inside which the subject is located it is possible to make effective stimuli that would be very difficult or even impossible to set in any real environment. We tested our system on healthy subjects and found out that this kind of virtual reality stimulation system is very useful for balance analysis.

Adult↗