PubMed Health⌕ Search

Biomedical subjects

S Uimonen

Publications and source records attributed to S Uimonen.

16 recordsLinked to original sources
PubMed2006

A 3-year clinical follow-up of adult patients with 3243A>G in mitochondrial DNA.

OBJECTIVE: To follow the clinical course of patients with the mitochondrial DNA mutation 3243A>G for 3 years. METHODS: Thirty-three adult patients with the 3243A>G mutation entered a 3-year follow-up study. They were clinically evaluated annually, audiometry was performed, and samples were drawn for the analysis of blood chemistry and mutation heteroplasmy in leukocytes. Holter recording was performed three times during the follow-up and echocardiography, neuropsychological assessment, and quantitative EEG and brain imaging conducted at entry and after 3 years. RESULTS: The incidence of new neurologic events was low during the 3-year follow-up. Sensorineural hearing impairment (SNHI) progressed, left ventricular wall thickness increased, mean alpha frequency in the occipital and parietal regions decreased, and the severity of disease index (modified Rankin score) progressed significantly. The rate of SNHI progression correlated with mutation heteroplasmy in muscle. The increase in left ventricular wall thickness was seen almost exclusively in diabetic patients. Seven patients died during the follow-up, and they were generally more severely affected than those who survived. CONCLUSIONS: Significant changes in the severity of disease, sensorineural hearing impairment, left ventricular hypertrophy, and quantitative EEG were seen in adult patients with 3243A>G during the 3-year follow-up.

Adult↗
PubMed2005

Prevalence of large-scale mitochondrial DNA deletions in an adult Finnish population.

BACKGROUND: Large-scale mitochondrial DNA (mtDNA) deletions are associated with clinical conditions such as Kearns-Sayre syndrome and chronic progressive external ophthalmoplegia in adults and Pearson syndrome in children. Reported case series have suggested that deletions are not uncommon in the population, but their prevalence has not been documented. METHODS: The authors ascertained patients with clinical features associated with mtDNA deletions in a defined adult population in northern Finland. Buccal epithelial samples were requested from each patient fulfilling the selection criteria, and full-length mtDNA was amplified using the long PCR method. Deletion breakpoints were identified using sequencing. Patients with deletions were examined clinically. RESULTS: The authors identified four patients with single large-scale mtDNA deletions. The prevalence of deletions was calculated to be 1.6/100,000 in the adult population in the province of Northern Ostrobothnia (0.0 to 3.2; 95% CI). Analysis of incident cases from a neighboring province revealed two patients with deletions and yielded a similar population frequency. CONCLUSIONS: The frequency of large-scale mitochondrial DNA deletions is similar among populations, suggesting that there is a constant rate of new deletions.

Adult↗
PubMed2001

Hearing impairment in patients with 3243A-->G mtDNA mutation: phenotype and rate of progression.

The relationship between the phenotype and the genotype is complex in diseases caused by mutations in mitochondrial DNA (mtDNA). The 3243A-->G mutation in mtDNA frequently leads to sensorineural hearing impairment (HI), a phenotype that can be assessed in severity by audiometry; hence, consecutive audiograms can give an estimate of the rate of HI progression. We examined the audiological phenotype of 38 patients (14 men, 24 women; mean age: 45+/-14 years) who possessed the 3243A-->G mutation and who belonged to a population-based cohort ascertained in the province of Northern Ostrobothnia, Finland. The subjects took part in an otorhinolaryngologic examination, including audiometry. Factors modulating the severity of HI were analyzed, and the rate of HI progression was calculated. The better ear hearing level (BEHL) at frequencies 0.5, 1, 2, and 4 kHz (BEHL0.5-4kHz) was greater than 20 dB suggesting HI in 28 patients (74%). A good correlation (r=0.428, P=0.009) was found between BEHL0.5-4kHz and the degree of the mutant heteroplasmy. BEHL0.5-4kHz was worse in men than in women, and women outnumbered men among patients with normal hearing or mild HI. In addition, 181 consecutive audiograms were reviewed from 24 patients with HI. The rate of HI progression was calculated to be 2.9 dB/year in men and 1.5 dB/year in women, being clearly faster than the rates that have been observed in the corresponding age group in the general population. A high degree of mutant heteroplasmy, male gender, and age were found to increase the severity of HI. Phenotypic difference by gender may thus be a more universal phenomenon in mitochondrial diseases, not only being associated with Leber's hereditary optic neuropathy. This study provides the first estimate of the rate of disease progression among patients with the 3243A-->G mutation.

Cohort Studies↗
PubMed2001

The Finnish speech-in-noise test in MELAS mutation and other sensorineural hearing impairments.

A computerized adaptive Finnish speech-in-noise test has recently been developed. The purpose of the present study was to measure speech recognition thresholds in noise (SRTN) in patients with sensorineural hearing impairment (SNHI) caused by mitochondrial mutation [mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS)] and in patients with SNHI from other causes and to compare them with those in normal hearing controls. SRTN differed significantly between controls and the patients with SNHI from other causes and between controls and the MELAS group, but not between SNHI patients and the MELAS group. Hearing in a noisy environment seems to be as impaired in MELAS patients as in patients with SNHI from other causes, in spite of the possible coexisting defects in the central nervous system.

Adult↗
PubMed2001

The Finnish speech in noise test for assessing sensorineural hearing loss.

A computerized adaptive Finnish speech in noise test was developed recently. As part of the test's evaluation process 172 patients with sensorineural hearing loss including 20 normally hearing subjects were measured using pure-tone audiometry, speech recognition threshold in noise (SRTN) test and conventional speech audiometry without background noise. As anticipated, sensorineural hearing loss yielded an elevation of SRTN although individual differences were considerable. The SRTN test was accurate as the absolute difference between individual repeated SRTNs was, on average, 1.5 dB (SD 1.5 dB) when the range of possible test values is from approximately -12 to +20 dB. On average, the learning effect was 0.5 dB.

Audiometry, Pure-Tone↗
PubMed2000

Frequency of mitochondrial DNA point mutations among patients with familial sensorineural hearing impairment.

Several point mutations in mitochondrial DNA (mtDNA) have been shown to cause sensorineural hearing impairment (SNHI), but the frequency of these mutations among patients is not known. We identified 117 patients with possible matrilineal SNHI from population-based registers and found the 3243A > G mutation to be present in 4.3% and 1555A > G in 2.6%, while 7445T > C, 7472insC and 8344A > G were absent. Patients with 3243A > G and 1555A > G were clinically distinct. The prevalence of 1555A > G in the general adult population was estimated to be at least 4.7/100,000, but these and previous data suggest that the figure may vary between populations. Screening for mtDNA mutations is worthwhile in connection with the diagnosis of SNHI.

Cohort Studies↗
PubMed1999

Do we know the real need for hearing rehabilitation at the population level? Hearing impairments in the 5- to 75-year-old cross-sectional Finnish population.

The cross-sectional population sample studied here was randomly selected from the population register of northern Finland. The subjects comprised 10 different age groups between 2 and 75 years of age. Pure tone averages over the frequencies of both 0.5, 1 and 2 kHz and 0.5, 1, 2 and 4 kHz - i.e. better ear hearing levels (BEHL) of BEHL0.5-2kH and BEHL0.5-4kHz - were calculated. The prevalence of various grades of hearing impairment was investigated among the 3518 people who participated in audiometric measurements. Two different classifications were used to grade the hearing impairment. According to the World Health Organization (WHO) classification (1991), 94.3% of the subjects had normal hearing, whereas 3.8% had mild hearing impairment, 1.3% had moderate impairment, 0.4% severe impairment and 0.1% profound impairment. When the more recent EU definition (1996) was used, 85.3% of the subjects had normal hearing. Mild impairment was found in 11.5% of the subjects, moderate impairment in 2.8%, severe impairment in 0.3%, and profound in 0.1%. The difference between the two definitions mentioned above (resulting in different prevalence figures of hearing impairments) is clear. The WHO classification reveals the need for rehabilitation and can thus be used as a basis of resource allocation, whereas the EU proposal reveals even the mildest hearing impairments and hence better illustrates the real prevalence of impairment. The need for the current and future audiological services may be estimated from the prevalence rates of hearing impairments. The proportion of the Finnish elderly - the people most frequently using health services - is expected to increase from today's 15% to 23% within the next 20 years. The same phenomenon is to be expected in other Western societies.

Adolescent↗
PubMed1998

Epidemiology of A3243G, the mutation for mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes: prevalence of the mutation in an adult population.

Mitochondrial diseases are characterized by considerable clinical variability and are most often caused by mutations in mtDNA. Because of the phenotypic variability, epidemiological studies of the frequency of these disorders have been difficult to perform. We studied the prevalence of the mtDNA mutation at nucleotide 3243 in an adult population of 245,201 individuals. This mutation is the most common molecular etiology of MELAS syndrome (mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes), one of the clinical entities among the mitochondrial disorders. Patients with diabetes mellitus, sensorineural hearing impairment, epilepsy, occipital brain infarct, ophthalmoplegia, cerebral white-matter disease, basal-ganglia calcifications, hypertrophic cardiomyopathy, or ataxia were ascertained on the basis of defined clinical criteria and family-history data. A total of 615 patients were identified, and 480 samples were examined for the mutation. The mutation was found in 11 pedigrees, and its frequency was calculated to be >=16. 3/100,000 in the adult population (95% confidence interval 11.3-21. 4/100,000). The mutation had arisen in the population at least nine times, as determined by mtDNA haplotyping. Clinical evaluation of the probands revealed a syndrome that most frequently consisted of hearing impairment, cognitive decline, and short stature. The high prevalence of the common MELAS mutation in the adult population suggests that mitochondrial disorders constitute one of the largest diagnostic categories of neurogenetic diseases.

Acidosis, Lactic↗
PubMed1998

Hearing and occupation.

Not only does the environment play a role as a source of risk factors for a hearing impairment, but a hearing impairment itself can adversely affect interaction with family members, workmates and friends, thus reducing social well-being. The number of work-related hearing impairments has been decreasing for last five years, but noise-induced sensorineural hearing loss is still the second most common work-related disease in Finland. The financial burden related to occupational hearing impairments includes costs of compensation, salaries of screening personnel, equipment, maintenance costs, costs resulting from loss of work for the employer and referrals to specialist clinics etc, which until now have not been calculated in Finland. Numerous questions still remain to be answered regarding the association of age, socioacousis, occupation and leisure activities with the development of sensorineural hearing impairment. Can hearing impairment acquired in childhood or in early adolescence predict the development of occupational hearing loss? What is the interactive role of such factors as ageing, chemicals, diet, environmental noise, genetic susceptibility and the individual's other diseases in the development of noise-induced hearing impairment?

Adolescent↗
PubMed1997

Hearing in 55 to 75 year old people in northern Finland--a comparison of two classifications of hearing impairment.

A total of 5,400 persons from different age groups was randomly selected from the population register for the study, and of the 1,620 55 to 75 year old persons invited, 1,233 attended the check-ups (76.1%). Air conduction pure tone thresholds were measured at the frequencies of 0.25, 0.5, 1, 2, 3, 4, 6 and 8 kHz. The findings were interpreted according to both the EU and WHO classifications. According to the WHO classification, 1,046 subjects (85.0%) had normal hearing and 124 persons (10.1%) had a mild hearing impairment, 44 (3.6%) a moderate, 13 (1.1%) a severe and 3 (0.2%) had a profound hearing impairment. According to the EU classification, 758 subjects (61.6%) were found to have normal hearing, a mild impairment was observed in 363 persons (29.5%), a moderate hearing impairment in 96 (7.8%) and a severe impairment in 13 (1.1%) persons. None had a profound hearing impairment. The difference between these classifications is remarkable as is evident in even this small study. A thorough discussion on the role of different gradings for hearing is needed.

Aged↗
PubMed1996

A comparison of three vibrators in static posturography: the effect of vibration amplitude on body sway.

In static posturography, proprioception is often disturbed using vibrators applied bilaterally to the calf muscles. The effect of vibrator amplitude on body sway was compared in static posturography using bilateral vibrators on the calf muscles of 30 healthy male military conscripts at frequencies of 50 and 90 Hz. Postural stability was measured in terms of BSV (body sway velocity), and maximal displacements of the centre of force (MAXY, MAXX) in the anterio-posterior and lateral directions. In comparing the effects of vibration to base stance without vibration, BSV seemed to be the most sensitive parameter. A vibration of 50 and 90 Hz significantly influenced BSV values with the two most eccentric loads, an effect which could not be confirmed using any other parameter. This result could be obtained even with a small amplitude (around 0.7 mm free/0.3 mm fixed) in our healthy subjects. The BSV effects may be even more pronounced in clinical work with patients and postural disorders. Thus, when proprioceptive stimulations is used in posturographic measurements, differences in the tested magnitude of the stimulation amplitude with a constant frequency will significantly affect postural stability, even in healthy subjects.

Acceleration↗
PubMed1994

The repeatability of posturographic measurements and the effects of sleep deprivation.

The repeatability of posturographic measurements and the effects of sleep deprivation on them were investigated in 23 volunteers over a period of four months. Postural stability was studied by evaluating body sway velocity and the maximal and average vibration-induced shifts of the centre of pressure in the anterio-posterior and lateral directions. The posturographic test was performed with and without exposure of the calf muscles to vibration. Subjects were tested both with their eyes open and closed, and the measurements were performed weekly during the first month and once every month thereafter. The interindividual results differed more than the intraindividual ones, indicating that posturographic measurements are most suitable for functional monitoring in one person's tests. The dispersion of the results did not diminish with time, nor did the body sway decrease. The findings suggest that no learning takes place in nontrained persons. In the second part of the research, measurements were performed twice after the subjects had been awake the previous night or 24 hours. Postural stability did not deteriorate in this situation.

Adult↗
PubMed1992

Effect of positioning of the feet in posturography.

Static posturography has been developed from a basic research test to a widely used clinical tool for evaluating dizzy patients. Before any actual standardization can be achieved, however, several aspects of the test situations have to be evaluated, including the position of the feet. The quantitative significance of the standing position in posturographic measurements was evaluated with healthy volunteers studied under visual and nonvisual conditions, using 4 foot positions: heels together with the toes 30 degrees apart or at an angle of the volunteer's own choice, and the feet parallel and either 0 or 10 cm apart were studied separately. Each measurement was characterized in terms of 5 parameters (body sway velocity, vibration-induced shift of centre of force in anteroposterior and lateral directions, and maximum displacement of centre of force in the same directions). Body sway velocities were smallest when the feet were parallel and 10 cm apart. Although the position chosen by the subject was usually more stable than that with the toes 30 degrees apart, the difference was nonsignificant. According to our results, the standing position is not crucial in posturographic measurements provided that the distance between the heels is determined, and the subject can just as well choose the angle between the feet if the heels are kept together.

Adult↗
PubMedDate not supplied

Does posturography differentiate malingerers from vertiginous patients?

Voluntary, simulated vertigo and acute vertigo due to vestibular neuritis were examined by means of static posturography in 81 tests to evaluate the extent to which intentional malingering can be detected. Thirty healthy, normal subjects were first instructed to stand as still as possible on a static force platform and then to simulate dizziness. The true cases consisted of 21 patients with vestibular neuritis. The parameters analyzed included body sway velocity (BSV), body sway area of ellipse (BSE), and the Romberg quotient. Both the simulated and pathological posturographic BSV and BSE values differed from normal values under all test conditions, but they did not differ from each other, whereas the simulated values could be differentiated from the pathological ones with the Romberg quotient based on BSV. Five staff members of our audiological department were able to differentiate between the simulations and pathological cases quite well, with a median sensitivity of 0.77 and a specificity of 0.71 in a blinded test. A posturographic measurement, even performed once, can be useful to some extent for detecting simulation, but more investigation and development of the analysis system is required to obtain more specific results. For the present, the results obtained by trained observation of the subject in the test situation are at least as reliable as those obtained through the analysis of statistical measurements.

Adult↗
PubMedDate not supplied

Static posturography and intravenous alcohol.

Twelve health subjects were assessed using static posturography before and after intravenous alcohol infusion in a double-blind experiment. The dose was 0.5 g ethanol per kg body weight in 15 minutes, which raised the blood alcohol concentration to a level of approximately 1 mg/mL. Among other parameters, the average body sway velocity (BSV) and area of body sway (BSA) were measured. BSV was the most sensitive parameter for detecting increased body sway after alcohol infusion, and a significant effect of alcohol on its values was seen at 0.46 to 1.0 mg/mL alcohol concentrations. The second best indicator was the BSA. There was a positive correlation between the BSV and the BSA. The other parameters were not affected. The Romberg quotient remained constant during the alcohol test. The test battery used was relevant to distinguish the effect of alcohol on balance. In this study, acute blood alcohol concentrations of around 0.5 to 1.0 mg/mL affected BSV more significantly than BSA. The authors do not, however, recommend the test for forensic purposes in examining drivers with alcohol in their blood, as there is too much interindividual dispersion in the results.

Adolescent↗