Biomedical subjects

E Isotalo

Publications and source records attributed to E Isotalo.

9 recordsLinked to original sources

PubMed2001

Effects of transcranial magnetic stimulation of the posterior parietal cortex on saccades and vergence.

Previous studies showed that transcranial magnetic stimulation (TMS) of the posterior parietal cortex (PPC) prolongs the latency of intentional saccades. We examined whether a similar effect exists for reflexive saccades and vergence. To elicit reflexive movements, a gap paradigm was used; lateral saccades and vergence along the median plane were interleaved. TMS was applied on the right PPC 80 ms after target onset. Blocks without TMS were performed and a control experiment with TMS over the primary motor cortex. The latter had no effect on the latency of any type of movements. In contrast, stimulation of the PPC increased the latency of both saccades and vergence, suggesting that the PPC is involved in the triggering of reflexive movements both in direction and in depth.

Adult↗

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↗

PubMed1999

Modelling oculomotor data with decision tree induction.

We studied relationships between oculomotor test results and the site of lesion in the data set containing patient cases with operated cerebello-pontine angle tumour, operated hemangioblastoma, infarction of cerebello-brainstem or Meniere's disease and control subjects. Several classification models were generated by decision tree induction to find parameter combinations which are efficient in classification. The studied data were characterised by missing values and scarcity of example cases. This study suggested that decision tree induction can be a useful method even in problematic real world classification tasks. Models generated by decision tree induction and evaluated by an expert physician may give information that is beneficial for research.

Brain Stem Infarctions↗

PubMed1997

Velopharyngeal function in association with artificial obstruction of the nose: a videonasendoscopic study.

Artificial obstruction of the nose can make the nasal cavity a cul-de-sac resonator, which has clearly audible consequences. The present study compares videonasendoscopic views of the velopharyngeal mechanism in test words uttered with the nose open and obstructed in 20 subjects with a Pierre Robin sequence and in 6 subjects without this sequence. A velopharyngeal flap was constructed on 12 subjects. Videonasendoscopic findings were assessed by 3 judges with acceptable agreement. The results indicated that impairment of velopharyngeal function occurred significantly more often in subjects with a velopharyngeal flap. This was attributed to aerodynamic reasons. Clinical implications of the results are discussed.

Adolescent↗

PubMed1997

Hemangioblastoma and oculomotor pathology.

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.

Case-Control Studies↗

PubMed1997

Oculomotor pathology in Menière's disease.

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.

Case-Control Studies↗

PubMed1995

Predictable and pseudo random saccades in patients with acoustic neuroma.

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.

Adult↗

PubMed1995

Pseudo random smooth pursuit test in patients with acoustic neuroma.

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.

Adolescent↗

PubMedDate not supplied

Correlation between speech outcome and cephalometric dimensions in patients with diastrophic dysplasia.

Diastrophic dysplasia (DTD) is a recessively inherited form of osteochondrodysplasia, presenting with disproportionate short stature and multiple orthopedic problems. The clinical oral manifestations include either cleft palate or submucous cleft palate in at least half of the patients. Histological studies have shown alterations in growth plate, articular, laryngeal, tracheal, and ear cartilages. Mutations in the DTDST gene, which codes for the sulphate transporter membrane protein, are responsible for the disease. Thirty-three patients were studied for speech characteristics and their correlation with cephalometric dimensions. Hyponasality was observed in 13 and misarticulation of /R/, /S/, or /L/ sounds in 17 of the 33 patients. Neither of these correlated with the occurrence of palatal deformities. Hyponasality was atypical and did not correlate with the obtained nasalance scores. Cephalometric measurements reflecting the size of the orofacial area of the vocal tract were short in the DTD patients compared with those in the healthy controls. The specific speech characteristics in DTD probably result from both the altered size and shape of the vocal tract and the structural and functional abnormalities of the laryngeal and tracheal cartilages.

Adolescent↗