Biomedical subjects

T Ledin

Publications and source records attributed to T Ledin.

At least 37 records · Page 2Linked to original sources

PubMed1996

The subjective horizontal in eccentric rotation influenced by peripheral vestibular lesion.

Peripheral vestibular equilibrium disorders may originate in various parts of the labyrinth or the vestibular nerve. Traditionally, the function of the lateral semicircular canals has been assessed with caloric irrigation, and sometimes falsely been interpreted as a vestibular nerve lesion. The vertical semicircular canals are not easily assessed. Caloric testing with the head in different positions is not very helpful, but the canals may pairwise be tested using specific rotational techniques. Often the otolithic organs, capable of detecting linear acceleration forces, are forgotten as a source of vertigo and dizziness. We have implemented horizontal rotatory testing with the subject seated eccentrically facing the direction of rotation as a means of assessing otolithic function. The subject experiences a lateral tilt and is instructed in darkness to put a short light bar in the position he thinks a water surface would have, which is identical to his perceived tilt. In 39 normal subjects, a theoretical tilt of 24 degrees was estimated as approximately 19.5 degrees, and the standard deviation was 6 degrees. A side difference index was proposed to be normal if below 25%. The preliminary findings in a few patients with known labyrinthine lesions are presented. We propose that otolithic as well as lateral semicircular canal functions are useful to monitor in patients with suspected peripheral equilibrium disorders.

Adult↗

PubMed1995

Effects of loratadine on postural control.

The effects of classical sedating antihistamines on cognitive and perceptual functions are well known. Loratadine is a new antihistamine without sedative effects. In this study, loratadine 10 and 40 mg daily, clemastine 2 mg twice daily and placebo were evaluated in 8 healthy subjects in terms of effects on equilibrium as measured with dynamic posturography. Dynamic posturography comprises a sensory organization part in which the support surface and visual surround are either stable or referenced to the patient's sway, with eyes open or closed. In a movement coordination part, the platform makes active movements. Analysis of variance showed no effects on equilibrium attributable to loratadine. Comparing substances pairwise, however, a significant difference between loratadine and clemastine was displayed in 2 out of 6 sensory test conditions. In conclusion, loratadine can be considered safe regarding balance functions.

Adult↗

PubMed1995

Postural control after propofol anaesthesia in minor surgery.

There is, not only from an economic perspective, a continuous search for surgical and anaesthetic procedures that allow out-patient surgery to be conducted. Reliable estimators of the patient's street fitness are of the utmost importance. Balancing capacity is one aspect that should be considered. Clinical methods like Romberg's are subjective and imprecise. Dynamic posturography comprises a movable support surface and visual surround that are either stable or referenced to the patient's sway, with eyes open or closed. In this study the recovery from propofol anaesthesia was studied in 8 patients who underwent surgery for minor microlaryngoscopic procedures. Dynamic posturography who performed before, and 2 and 4 h after cessation of anaesthesia. All patients who were awake had normal balancing ability already at 2 h after anaesthesia. Further studies may supply additional information of other aspects of discharge after anaesthesia.

Adult↗

PubMed1995

Influence of cerebrospinal fluid tapping on dynamic equilibrium in suspected hydrocephalus.

Thirty-nine patients aged 21-82 years (mean 62 years) under investigation for suspected acquired hydrocephalus were investigated by dynamic posturography before and 6-8 h after a cerebrospinal fluid tap of 20-40 ml. Dynamic posturography comprises a sensory organization (SO) part in which the platform and visual surround are either stable or referenced to the patient's sway. The eyes are closed or open. In a movement coordination (MC) part the platform makes active movements, thus introducing external disturbances in the procedure. The patients improved their balancing ability in all tests on the sway referenced platform in SO, while MC remained unaffected. It is concluded that dynamic posturography is valuable for dysequilibrium assessment in clinical evaluation of suitable candidates for ventricular shunts in acquired hydrocephalus.

Adult↗

PubMed1995

Randomized perturbed posturography in abstinent chronic alcoholics.

Equilibrium is maintained by visual, proprioceptive and vestibular afferent influx, central coordination and motor efferents. Eleven male abstinent chronic alcoholic volunteers aged 44-65 years (mean 57 years) were investigated by randomized perturbed posturography. They had all been long time heavy drinkers. Ocular smooth pursuit and visual suppression of the vestibulo-ocular reflex showed abnormalities in a previous study, but they had no signs or symptoms of polyneuropathy. The current study demonstrated larger (but generally not significantly so) sway areas, and in all tests on the randomly moving support surface the sway velocities were significantly larger than in the controls. It is concluded that randomized perturbed posturography is valuable in dysequilibrium assessment in chronic alcoholics.

Adult↗

PubMed1993

Randomized perturbed posturography: methodology and effects of midazolam sedation.

To study quiescent stance without applying external disturbances is not a theoretically appealing way to unveil the dynamic properties of human equilibrium. Methods to disturb equilibrium range from standing on foam surface, attaching vibrators to the calves to interfere with somatosensation, and exposure to body-position tracking environments, as in dynamic posturography (EquiTest). The EquiTest apparatus was modified by a menu-driven software to allow arbitrary movements of the support surface and visual surround, and force data were recorded for subsequent analysis. The support surface was randomly moved in the antero-posterior direction. First equilibrium was studied on the stable support surface, then low (RMS 1.3 cm) and high (RMS 2.6 cm) amplitude movements were used. Vision was either present or absent at all test amplitudes. Equilibrium was evaluated by the confidence (61%) ellipse sway area and average sway velocity during 45 s. Eleven healthy subjects aged 23-36 years (mean 29) were sedated with a short acting sedative, midazolam 0.1 mg/kg. Randomized perturbed posturography was conducted at baseline, and at about 60, 120 and 180 min after injection. Psychomotor tests were conducted at baseline, and at 30, 90, 150 and 210 min. Large interindividual variations were found. One subject could not be tested at all at 60 min due to sleepiness, whereas some subjects felt nearly full awake at 30 min. Sway areas were larger at 60 min, but not subsequently. At 60 min, sway velocities with open eyes were higher, just as when vision was absent and low amplitude movements were used. Later no effects could be shown.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Effects of increased inertial load in dynamic and randomized perturbed posturography.

Muscular weakness is present in many diseases. The present study attempted to model a relative weakness of postural control muscles by loading the subjects with extra weight, and the effects on EquiTest dynamic posturography and randomized perturbed posturography were assessed. Ten healthy subjects aged 15-39 years (mean 26 years) were used. Their weights ranged 53-82 kg. Equilibrium was measured with and without an extra 20% of body weight attached to the upper part of the trunk by means of pieces of lead metal placed in a specially sewn shirt. Dynamic posturography (EquiTest) comprises a sensory organization test in which the support surface and visual surround are either stable or referenced to the patient's sway, his or her eyes open or closed. In a movement coordination part the platform makes active movements. Antero-posterior sway on a stable support surface with absent or distorted visual cues was marred, and the correction pattern was altered on a movable support surface when the vision was absent. Furthermore, the EquiTest apparatus was driven by special software to produce randomized antero-posterior movements during 45 s. In addition to stable conditions, small and large amplitude perturbations were used. The subject's ability to remain in equilibrium was estimated by the sway velocity and a confidence ellipse sway area during 45 s. During weightbearing, sway areas were larger on the stable support surface both with and without vision. Postural sway velocity was lower when vision was absent both using small and large amplitudes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Dynamic posturography among patients with common neck disorders. A study of 15 cases with suspected cervical vertigo.

We have studied a consecutive series of 15 patients with long-lasting common neck pain combined with vertigo and/or unsteadiness by dynamic posturography with the head in different positions. The evaluation of disturbed equilibrium was done in the anteroposterior direction. Results were compared with 15 sex- and age-matched healthy controls and 10 patients with long-lasting neck complaints without vertigo or unsteadiness. The otoneurological, audiometrical, and electronystagmographical examination was normal in all individuals. The dynamic posturography on a sway-referenced forceplate showed significantly lower equilibrium scores in the patients with vertigo/unsteadiness than in the controls when recorded in neutral position of the head, in rotation and in lateral flexion. The patients with vertigo also had significantly lower equilibrium scores in the position most prone to elicit their vertigo/unsteadiness as compared with the patients with only neck pain. Dynamic posturography was found to be of diagnostic value, indicating the presence of vertigo of cervical origin.

Adult↗

PubMed1992

Psychomotor recovery following propofol or isoflurane anaesthesia for day-care surgery.

A newly developed test for the assessment of psychomotor recovery--the perceptive accuracy test (PAT)--is described. Seventy-four subjects who performed the test though that it was easy to perform and some were motivated to try it on a number of occasions. Eight persons performed the test on different days and at different periods of time; the results were consistent and reproducible. Eight more persons were then asked to do the test 4 times at 15-min intervals; no 'learning' was seen with this test. A randomized, prospective study was then performed in two groups of 15 patients, undergoing arthroscopic procedures of the knee. Anaesthesia was induced with propofol and maintained with an infusion of propofol 12 mg/kg/h for the first 15 min, followed by 8 mg/kg/h subsequently in the propofol group. In the isoflurane group, anaesthesia was also induced with propofol, but isoflurane (0.5-2%) was used to maintain anaesthesia. Alfentanil was the analgesic used in both groups of patients. Results were compared with a third group of unanaesthetised controls, who were asked to perform psychomotor tests including choice reaction time and PAT at 30-min intervals for 2.5 h. There was a significant difference (P less than 0.01) in psychomotor recovery on the PAT-200 between the propofol group and control groups, but not in the isoflurane and control groups at 30 min. Both groups had returned to baseline values at 60 min in the PAT-60 and PAT-200. The choice reaction time showed no significant difference in either group 30 min after the anaesthetic.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Delayed neurological adaptation in infants delivered by elective cesarean section and the relation to catecholamine levels.

We have studied the effect of mode of delivery and catecholamine (CA) surge at birth on neurobehaviour 1, 2 and 5 days after birth. Fifteen full-term infants were delivered by elective cesarean section (CS) and 15 full-term control infants were born vaginally. Infants born after elective CS were less excitable and had significantly reduced number of optimal responses during the first 2 days after delivery, compared to the controls. On the 5th day no significant neurological differences were found between the groups. Adrenaline and noradrenaline (NA) in umbilical arterial plasma were analysed in all infants. The mean values of NA were lower in the CS infants as compared to the vaginally delivered infants. Statistically significant correlations were found between low CA levels and poor muscle tone and/or lower grade of excitability in the CS infants. These results suggest that the high CA surge at birth might be of importance for the neurological adaptation after birth.

Adaptation, Physiological↗

PubMed1991

Computerized dynamic posturography: a new method for the evaluation of postural stability following anaesthesia.

Dynamic posturography, a new method to study postural stability in humans, was performed in 11 healthy volunteers before administration of midazolam 0.1 mg/kg body weight i.v., and repeated subsequently at 45, 105 and 165 min. Results indicate that balance was affected significantly (P less than 0.008) up to 45 min after i.v. midazolam and did not return to control values until 105 min. The quantified version of the Romberg test performed with the eyes open or closed using the Equitest did not appear to be sensitive in detecting residual effects of midazolam on balance. We conclude that healthy, young persons should not be considered to have regained postural stability for up to 105 min after sedation with midazolam. Dynamic posturography appears to be a useful test in the objective assessment of balance disturbances.

Adult↗

PubMed1991

Correlation between dynamic posturography, clinical investigation, and neurography in patients with polyneuropathy.

Dynamic posturography (PG) is a new objective method to study functional performance in diseases affecting balance. It measures muscle response latencies and sway angles to standardized alterations of a moveable platform and moveable surroundings. Twenty-eight patients with polyneuropathy (PN) were studied by clinical investigation, vibrametry, neurography, and dynamic PG. The results of dynamic PG and vibrametry were compared with those of 29 healthy controls. In the patients with PN, clinical scores correlated to the latencies of the muscle response when the platform was suddenly moved forward, and to equilibrium performance (sway angles) in dynamic PG test conditions with eyes closed and the platform either stable or 'sway-referenced'. That is, the platform moves in response to the patient's anterior-posterior sway, creating a disturbed proprioceptive input to the brain. Clinical scores also correlated to the equilibrium performance when both platform and surroundings were sway-referenced. In conclusion dynamic PG, in addition to clinical investigations and neurophysiology, is a valuable and objective method for estimating the equilibrium performance in patients with PN.

Aged↗

PubMed1991

Effect of alcohol measured by dynamic posturography.

Thirteen healthy male volunteers aged 21-42 years (mean 27 years) were assessed by dynamic posturography before and after ingestion of alcohol. Each subject was given 0.6 g alcohol per kg body weight in fruit juice to be drunk within 10 min. Alcohol levels in blood samples at 15, 45 and 75 min after ingestion were assessed by gas chromatography. Posturographic measurements were conducted at 30 and 60 min after alcohol administration. Dynamic posturography comprises a sensory organization part in which the support surface and visual surround are either stable or referenced to the patient's sway and the test conditions are eyes open or eyes closed. In a movement coordination part the platform makes active movements. Alcohol levels were 0.40% (SD 0.14) after 45 min and 0.51% (SD 0.14) at 75 min. All subjects presented positional alcohol nystagmus and gaze nystagmus after 45 min. In the sensory organization part of the dynamic posturography in test conditions with eyes closed and the head in neutral position, both with stable (p less than 0.039) and sway-referenced platform (p less than 0.017), alcohol effects were found. In the test condition with sway referenced platform and stable visual surround the effect of alcohol was close to significance (p less than 0.069). When the head was tilted to either side, no effect of alcohol was detected, nor in the movement coordination test. It is concluded that dynamic posturography can detect the effect of alcohol on static and dynamic equilibrium. Test conditions with absent vision appear to be the most sensitive. The results in static conditions are well in agreement with previous studies; the findings under dynamic conditions are new.

Adult↗

PubMed1991

Dynamic posturography in cervical vertigo.

Cervical vertigo, the entity of neck disorder and associated vestibular symptoms, was investigated in 15 suspected subjects and results were compared with 15 age-matched controls. A modified dynamic posturography investigation with different head positions was used. Head position was recorded 3-dimensionally with electrogoniometry. Differences on a sway-referenced forceplate were found.

Adult↗

PubMed1991

Abstinent chronic alcoholics investigated by dynamic posturography, ocular smooth pursuit and visual suppression.

Eleven male chronic alcoholic volunteers aged 44-65 years (mean 57 years) were investigated by dynamic posturography, ocular smooth pursuit and visual suppression of the vestibulo-ocular reflex (VOR). Their drinking time ranged from 8-30 years (mean 20 years) and they had been abstinent for the last 1-20 years (mean 7 years). Ocular smooth pursuit showed abnormalities in 8/11. Abnormalities were found in 5/11 in the visual suppression of the VOR. The results of dynamic posturography tests were compared to an age-matched reference material. Dynamic posturography (EquiTest) comprises a sensory organization (SO) part in which the support surface and visual surround are either stable or referenced to the patient's sway, with eyes open or closed. In the SO part the chronic alcoholics had lower equilibrium scores in all test conditions, and the differences were significant in 4 tests out of 6. In a movement coordination part the platform makes active movements, the latencies to which were significantly prolonged in the 2 larger of the 3 translational amplitudes. Adaptation to repeated tilting of the platform was estimated to be pathological in 4/10, compared to none of the controls. The abnormal pattern found in dynamic posturography correlates well with the pathology in ocular smooth pursuit and visual suppression tests, suggested to be due to alcohol induced cerebellar lesions. It is concluded that dynamic posturography is a valuable test for assessing dysequilibrium in chronic alcoholics, even abstinent.

Adult↗

PubMed1991

Visual influence on postural reactions to sudden antero-posterior support surface movements.

Visual influence on force reactions to sudden antero-posterior (AP) translations of the support surface in 10 healthy men 23-58 years old (mean 36 years) were studied. Displacements ranged between 13 and 127 mm in both backwards and forwards directions. The experiment was conducted using a modified EquiTest dynamic posturography apparatus. An interactive menu-driven software enabled selection of a suitable translation pattern (i.e. square wave) in the AP direction. Data from four vertical force transducers were acquired and the position of centre of pressure (CP) in the AP direction was computed as function of time. The movement of CP in response to AP translation was characterized by the amplitude of the maximum CP displacement relative to the platform and the latency until maximum CP displacement occurred. The experiment unveiled that the latency to maximum CP displacement was larger for conditions with vision present. Furthermore, both the amplitude and latency to maximum CP deflection were increasing functions of translation amplitude. It is proposed that visual feedback influences the neural control on the postural reactions to sudden support surface translations. Absence of visual cues seems to cause a more rapid correction of the body position.

Adult↗

PubMed1990

Influence of elective cesarean section and breech delivery on neonatal neurological condition.

Fifty-three infants born after elective cesarean section (CS), and 28 infants born vaginally in breech presentation were compared with 45 full-term controls. A quantitative neurological assessment consisting of 31 items was performed on days 1, 2 and 5 after birth. A tonus score, an excitability score and the number of optimal responses were calculated. A follow-up examination was done at 6 months of age, with a standardized neurological and developmental examination. The results showed that infants born after elective CS in both vertex and breech presentation had significantly reduced number of optimal responses during the first five days after delivery, compared to controls. They were more hypotonic and less excitable than the control infants during the first 2 days. There were no significant differences in neurological results between infants born after CS with general or epidural anaesthesia. The infants born in vaginal breech presentation showed no differences neurologically as compared to the controls on the first day. On days 2 and 5, however, they were less excitable and showed a reduced number of optimal responses. There were few differences in neurological condition between the infants born after elective CS and the infants born vaginally in breech presentation. Growth, psychomotor development and neurological status at 6 months did not differ significantly between the three groups. Our findings indicate that infants born after elective CS and vaginal breech presentation have a delayed neurological adaptation during their first days of life. These differences did not affect the physical well-being of the infants, which showed normal growth, neurology and development at the follow-up at 6 months of age.

Apgar Score↗

PubMed1990

Squamous cell carcinoma of the oral cavity. A review of 176 cases with application of malignancy grading and DNA measurements.

This retrospective study comprised 176 patients with squamous cell carcinoma of the oral cavity treated at The Linköping University Hospital over a 19-year period. Clinical parameters, microscopic malignancy grading (according to Jakobsson et al. and Glanz and Eichhorn), DNA cytofluorometry, analysis of therapeutic modalities and statistics regarding survival and prognosis are reported. The mean age was 70 years with a male: female ratio of 1.3:1 One hundred and four patients had T1 or T2 tumours and 109 an N0 neck. Cervical lymph node metastases were more frequent in patients with larger tumours (T3 + T4) than in those with smaller (T1 + T2) (P less than 0.01), in tumours with a high malignancy grading compared to those with a low (P less than 0.05) and in DNA non-diploid tumours compared to diploid ones (P less than 0.001). The aneuploid tumours responded better to preoperative radiotherapy than did diploid (P less than 0.01) or polyploid (P less than 0.05) tumours. Eighty-nine per cent of the recurrences occurred within 1 year of initial therapy. Secondary treatment was successful in 15 of 37 (41%) patients in whom the tumour recurred either at the primary site or in regional lymph nodes, but only in 1 of 8 (12%) with recurrences in both locations. Surgery alone or combined with radiotherapy resulted in equivalent survival rates for tumours in stages I and II. In advanced stages combined radiotherapy and surgery gave better survival figures than either modality alone (P less than 0.01; Kaplan-Meier). The presence of lymph node metastases (P less than 0.001), tumour size (P less than 0.01) and tumour ploidy (P less than 0.005) were the only clinical and histological parameters that significantly influenced survival (Cox regression analysis). Twenty-four patients developed a secondary primary malignancy; 21 of these were located in the aerodigestive tract.

Aged↗