[Vibrations as the cause of low back pain disorders. Professional drivers are at risk].
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Automobile Driving↗
Biomedical subjects
M Magnusson
Publications and source records attributed to M Magnusson.
Fracture of the mandibular condyle causing meningeal bleeding.
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Child↗
Colour Doppler ultrasound in diagnosing venous insufficiency. A comparison to descending phlebography.
OBJECTIVE: To evaluate the technique of ultrasound colour Doppler in diagnosing venous valvular incompetence in the lower leg. DESIGN: Prospective clinical study. SETTING: Department of clinical physiology. MATERIALS: 44 patients (56 legs) referred with a clinical diagnosis of deep venous insufficiency. CHIEF OUTCOME MEASURES: Colour Doppler and descending phlebography. MAIN RESULTS: Using phlebography as a "gold standard" the accuracy of the colour Doppler technique varied between 93% and 55% for the different veins. For the superficial and deep femoral veins, the popliteal vein and the long and short saphenous veins the accuracy was between 90% and 70%. The lowest correlation was found for the deep calf veins (55-66% accuracy). CONCLUSIONS: Colour Doppler was found to be a suitable technique for non-invasive investigation of patients with suspected venous insufficiency. Since the colour Doppler technique is non-invasive it is well suited for follow-up studies. Descending phlebography should be reserved as an adjunct technique in patients scheduled for valve reconstructive surgery.
Adolescent↗
Use and standardization of the Mycobacterium avium sensitin skin-test reagent.
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Humans↗
Galvanic vestibular stimulation for analysis of postural adaptation and stability.
Human postural dynamics was investigated in 12 normal subjects by means of a force platform recording body sway, induced by bipolar transmastoid galvanic stimulation of the vestibular nerve and labyrinth. The model adopted was that of an inverted segmented pendulum, the dynamics of postural control being assumed to be reflected in the stabilizing forces actuated by the feet as a result of complex muscular activity subject to state feedback of body sway and position. Time-series analysis demonstrates that a transfer function from stimulus to sway-force response with specific parameters can be identified. In addition, adaptation to the vestibular stimulus is demonstrated to exist, and we describe this phenomenon using quantification in terms of a postural adaptation time constant in the range of 40-50 s. The results suggest means to evaluate adaptive behavior and postural control in the erect human being which may be useful in the rehabilitation of individuals striving to regain upright stance.
Adaptation, Physiological↗
Isolated acute vertigo in the elderly; vestibular or vascular disease?
INTRODUCTION: Elderly patients with isolated acute vertigo are commonly encountered in clinical practice, but little is known about the underlying cause of the symptoms. MATERIAL & METHODS: We prospectively studied 24 patients aged 50-75 years with the acute onset of isolated vertigo lasting > 48 h and no abnormality on neurological examination other than nystagmus. The study protocol included neuro-imaging (MRI 22 patients, CT 2 patients), Doppler sonography, and electro-oculography. RESULTS: MRI/CT showed the presence of an infarction of the caudal cerebellum in six patients (25%), 3 of whom had a potential cardioembolic source and normal Doppler sonography findings, whereas 3 patients had ipsilateral vertebral artery occlusion and normal cardiac findings. MRI of the posterior fossa was normal in 18 patients. On electro-oculography, ataxic pursuit eye movements was a characteristic finding in patients with cerebellar infarction, whereas caloric test findings were not discriminative. CONCLUSION: A caudal cerebellar infarction may easily be misdiagnosed clinically as a labyrinthine disorder, and was found to be the cause in one fourth of patients presenting with isolated acute vertigo.
Acute Disease↗
Discrimination of patients with acoustic neuroma and peripheral vestibular lesions with human posture dynamics.
A group of normal subjects (n = 17) was compared with groups of patients with a diagnosis of vestibular neuritis (n = 18), and acoustic neuromas (n = 35). Fisher linear discriminant analysis was applied to distinguish clusters of parameters characteristic for each disease. Hence it was possible to distinguish the vestibular neuritis patients from the normal group with statistical significance (p < 0.01). Also the patients with an acoustic neuroma could be distinguished from the normal subjects with statistical significance (p < 0.05).
Diagnosis, Differential↗
Postural control and vestibular function in patients selected for cochlear implantation.
Postural control and vestibular and eye motor function were evaluated in 7 postlingually deaf patients before cochlear implantation as vibration toward the calf muscles or galvanic electrical stimulation of the vestibular nerves perturbed stance. The patients were compared with 21 control subjects. Vibration-induced bodysway was increased in the patients compared to the normals. Galvanic stimulation induced a bodysway that was not significantly different from that of the control group suggesting that the patients selected for cochlear implantation, and with otherwise reduced postural control, are sensitive to electrical stimulation of the vestibular nerve. This finding may contribute with a complementary hypothesis to the causes of dizziness among cochlear implant patients.
Adult↗
Impaired postural control in patients with cervico-brachial pain.
Dizziness and subjective balance disturbances are common complaints in cervical pain syndromes. We assessed balance function with posturography using vibration-induced and galvanically-induced body sway in consecutive patients (n = 116) with cervico-brachial pain syndrome of more than 3 months' duration. A total of 83% of the patients showed signs of cervical root compression on MRT scans. The incidence of complaints of vertigo was 50%. The patients manifested significantly poorer postural control than sex- and age-matched controls (n = 20). Disorders of the neck should be considered when assessing patients complaining of dizziness, vertigo and balance disturbances.
Afferent Pathways↗
Vestibular stimulation perturbs human stance also at higher frequencies.
The effect of primary vestibular disturbance on postural control was investigated in 11 normal subjects exposed to perturbation by bi-polar binaural galvanic stimulation of the vestibular nerve. The stimulus consisted of 30 s of sinusoidal galvanic stimulation at frequencies of 0.2, 0.3, 0.5, 1.0, 1.5, 2.0, 3.0 and 4.0 Hz, with a current of +/- 1 mA, the subject standing with open or closed eyes and the response evoked being recorded with a force platform. As compared with resting values, i.e. no stimuli, variance of lateral body sway was significantly greater at all frequencies tested in the closed eyes condition and at frequencies of 0.2, 0.5, 1.0, 3.0 and 4.0 Hz in the open eyes condition; using a high pass filter with a cut-off frequency of 0.1 Hz, variance of lateral body sway was significantly greater at frequencies 0.2, 0.3, 0.5, 1.0 and 2.0 Hz in the closed eyes condition and at frequencies 0.5 and 2.0 Hz in the open eyes condition. These findings suggest that in the lateral plane vestibular input affects and probably contributes to human postural control over a wider frequency range than suggested by findings in previous studies. Moreover, the visual contribution appears to enable the subject to suppress vestibular input causing lateral body sway only in the lower frequency range (here at 0.2 and 0.3 Hz). This evidence of vestibular contribution to postural control in the lateral plane is consistent with the response characteristics of the vestibulo-ocular reflex.
Adolescent↗
Postural control and vestibulospinal function in patients selected for cochlear implantation.
Postural control, vestibular and eye motor function were evaluated in seven postlingually deaf patients before cochlear implantation and were compared with 21 control subjects. Vibration to the calf muscles or galvanic electrical stimulation of the vestibular nerves, perturbed stance and body sway velocity, statistical variance of antero-posterior body sway and identification of characteristic parameters of postural dynamics were all evaluated. Vibration-induced body sway was increased among the patients compared with the normal subjects and there were differences in characteristic parameters of postural dynamics, indicating decreased postural control. Galvanic stimulation induced a body sway not significantly different from the control group suggesting that the patients selected for cochlear implantation, and with an otherwise reduced postural control, are sensitive to electrical stimulation of the vestibular nerve. Thus, postlingually deaf subjects who perceive a sensation of sound at electrical promontorial stimulation also respond with increased body sway to electrical stimulation aimed at the vestibular nerves. This finding may contribute an additional hypothesis to the causes of dizziness among cochlear implant patients, complementary to the that of wrongly placed electrodes and peroperative vestibular lesions.
Adult↗
Membrane-guided bone regeneration. Segmental radius defects studied in the rabbit.
We tested the principle of guided tissue regeneration (GTR) for healing segmental long-bone defects. 7 mm (3 animals) or 10 mm (5 animals) long segmental defects were created in the diaphyses of both radii in 8 rabbits. The defect on one side was covered with a barrier membrane of expanded polytetrafluoroethylene membrane shaped as a tube, while the contralateral side with no membrane served as the control. Healing was followed with radiographs obtained repeatedly during a 13- (n 3) or 27- (n 5) week period. Thereafter, the animals were killed and ground sections of the defect sites were prepared for histologic examination. Radiographically, the control sites showed some early subperiosteal callus formation and nonunion of the defects after 6 weeks. The bone ends were rounded off and sealed with cortical bone. No major changes were noted after 6 weeks. At the test sites, subperiosteal bone formation at the bone ends was first observed radiographically at 2 weeks. At 9 weeks, a thin cortical bone bridged the defect along the inner surface of the membrane. Histologically, an interrupted line of thin, cortical bone was observed along the inner surface of the barrier membrane. Fatty bone marrow occupied the central and largest volume of the defect. We conclude that it seems possible to use the principle of GTR to accomplish bone union of segmental long-bone defects.
Animals↗
Acoustic cues and postural control.
The effect of auditory input on postural control was evaluated in separate experiments performed in three groups of healthy volunteers. Auditory input took the form either of feedback signals generated by a force platform in response to the subject's postural control movements, or of field orientation (frame of reference) input provided by repeated clicks emitted by loudspeakers in a normally reverberative environment. The effect of these acoustic cues was measured in terms of body sway recorded on a force platform during stance perturbations induced by vibratory stimuli applied to the calf muscles either at low (120mW) or high (850 mW) intensity, the subject standing with eyes closed or open, as instructed. In the presence of feedback auditory input, body sway in response to low intensity vibratory stimulation was significantly reduced, but not that in response to high intensity stimulation. This may be due to the fact that the head and body movements induced by high intensity vibratory stimulation are so rapid and powerful that they override the information available or to the subject using other strategies for postural control in which auditory feedback, at least in the form used here, does not contribute useful information. The availability of field orientation input did not reduce body sway in response to vibratory stimulation at low intensity. This was probably due to the cognitive lag which precluded use being made of the input before the fast proprioceptive responses to vibratory stimulation had already occurred.
Acoustic Stimulation↗
Short vestibulo-ocular reflex time-constant in complete unilateral vestibular lesions.
The time-constant of the vestibulo-ocular reflex (VORtc) in response to short accelerations was studied in 18 patients with complete unilateral vestibular lesions: 12 patients with incomplete lesions and 9 healthy controls. The marked group differences in VORtc, which was short in patients with complete lesions and long (i.e., > or = 10 s) in the controls and some patients with incomplete lesions, suggests the finding of a long VORtc in a patient with a unilateral vestibular lesion to indicate the presence of an incomplete lesion. Moreover, one analytic method (where the initial phase of decay is weighted) showed the VORtc to be longer following stimulation toward the healthy ear than following stimulation toward the lesioned ear, whereas other analytic methods showed no direction asymmetry in VORtc.
Adult↗
The effect of seat back inclination on spine height changes.
The effect of backrest inclination on spinal height changes was tested during static sitting and seated whole-body vibrations. The vibration input was sinusoidal with a frequency of 5 Hz and an acceleration of 0.1 g rms. The backrest inclinations tested were 110 degrees and 120 degrees . The 110 degrees backrest caused less shrinkage than did the 120 degrees during static sitting, whereas the opposite was true when vibration was present, although the differences between the backrests were not statistically significant. Only when the results were compared with results from exposure to unsupported sitting were the differences statistically significant for both static sitting and seated vibrations when the 110 degrees backrest was used and for vibration with the 120 degrees backrest. Thus we conclude that an inclined backrest reduces the effects of vibration. More importantly, emphasis should be placed upon seats and seat materials that can attenuate vibration.
Journal Article↗
Comparative skin testing with PPD tuberculin, Mycobacterium avium and M. scrofulaceum sensitin in schoolchildren in Saudi Arabia.
SETTING: Jizan region, Saudi Arabia. OBJECTIVE: To test methodology for studies of tuberculin sensitivity and effectiveness of BCG vaccination programme. DESIGN: School children (n = 315) aged 6-12 years simultaneously tested intradermally with PPD tuberculin RT23, 2TU and 0.1 microgram Mycobacterium avium or M. scrofulaceum sensitin. Presence of BCG scar as evidence of previous BCG vaccination. Cervical lymph nodes palpated. RESULTS: BCG coverage was 75%. The prevalences of positive reactions (induration > or = 6 mm) were higher among children with than without scar. Prevalences of positive reactions to PPD and M. scrofulaceum sensitin were higher among girls than boys. In children with scar, the mean size of positive reactions to PPD was larger among girls than boys, and the prevalence of positive reactions was smaller in this group among children with than without palpable cervical lymph nodes. The sizes of reactions both to M. avium and to M. scrofulaceum sensitin were correlated to the size of the tuberculin reactions. Previous admission to hospital was reported less often by children with than without scar. CONCLUSIONS: The technique applied and training of staff was satisfactory. In further studies, however, we will apply three simultaneous tests to each person.
Age Factors↗
Dual skin testing with Mycobacterium avium sensitin and purified protein derivative: an open study of patients with M. avium complex infection or tuberculosis.
The sensitivity and specificity of dual mycobacterial skin testing were assessed in an unblinded study of 22 patients with culture-confirmed Mycobacterium avium complex (MAC) infection and 20 patients with culture-confirmed Mycobacterium tuberculosis infection. Intradermal skin tests were performed with 0.1 mL of M. avium sensitin, 0.1 mL of PPD (purified protein derivative), and two control antigens (mumps and Candida). All patients with M. tuberculosis infection reacted to the skin tests; the mean reaction size was 19.7 +/- 1.4 mm when PPD was administered and 10.3 +/- 1.5 mm when M. avium sensitin was administered. Four patients with MAC were anergic; for the remaining 18, mean reactions of 15.2 +/- 1.4 mm to M. avium sensitin and 4.3 +/- 1.3 to PPD were noted. A skin test was defined as M. avium-dominant or PPD (M. tuberculosis)-dominant if there was a minimum reaction size of > or = 5 mm to the given species, and the reaction to the given species was > or = 3 mm greater than the reaction to the heterologous species. Dominant skin test reactions were present in 18 (90%) of 20 patients with M. tuberculosis and 15 (83%) of 18 nonanergic patients with MAC. The specificity of dominant skin tests was 100% for infection with M. tuberculosis and 100% for infection with MAC. M. avium-dominant skin tests identify subjects with prior MAC infection and distinguish them from patients with M. tuberculosis infection.
Adult↗
Characterization of purified protein derivative of tuberculin by use of monoclonal antibodies: isolation of a delayed-type hypersensitivity reactive component from M. tuberculosis culture filtrate.
Nine monoclonal antibodies were raised against purified protein derivative (PPD) of tuberculin in mice previously treated with Bacilli Calmette Guérin (BCG). The antibodies also reacted with a culture filtrate from Mycobacterium tuberculosis strain H37Rv. In immunoblotting after SDS-PAGE the reaction with PPD was seen as a diffuse smear, whereas ammonium sulphate-precipitated proteins from H37Rv gave well-defined bands ranging from 10 to 65 kDa. Enzyme immunoassay showed that both PPD and H37Rv antigens were able to inhibit binding of the antibodies to PPD coated microtitre wells, suggesting that the antibodies reacted with continuous epitopes. A 12 kDa protein purified by immunoaffinity chromatography from H37Rv antigens was tested intradermally in M. tuberculosis MNC3 sensitized guinea pigs and gave a delayed type hypersensitivity reaction.
Animals↗