Faculty Bibliography

1. In healthy human subjects holding the index finger semi-extended at the metacarpophalangeal joint against a moderate load, electromyographic (EMG) activity was recorded from the finger extensor and flexor muscles during different stages of muscle fatigue. The aim was to study the effect of muscle fatigue on the level of background EMG activity and on the reflex responses to torque pulses causing sudden extensor unloadings. Paired comparisons were made between the averaged EMG and finger deflection responses under two conditions: (1) at a stage of fatigue (following a sustained co-contraction) when great effort was required to maintain the finger position, and (2) under non-fatigue conditions while the subject tried to produce similar background EMG levels to those in the corresponding fatigue trials. 2. Both the unloading reflex in the extensor and the concurrent stretch reflex in the flexor were significantly less pronounced and had a longer latency in the fatigue trials. Consequently, the finger deflections had a larger amplitude and were arrested later in the fatigue trials. 3. It is concluded that--with avoidance of 'automatic gain compensation', i.e. reflex modifications attributable to differences in background EMG levels--the servo-like action of the unloading and stretch reflexes is reduced in fatigued finger extensor and flexor muscles

STUDY DESIGN. The results of a survey organized in the school system of the Swiss canton of Fribourg. An original questionnaire was developed for this study are reported. OBJECTIVES. The goal of this study was to evaluate the possible role of familial or psychological factors in schoolchildren reporting nonspecific low back pain. SUMMARY OF BACKGROUND DATA. Previous surveys have shown a high prevalence of nonspecific low back. pain among schoolchildren, particularly teen-agers. The reported familial incidence raises, among others, the question of a possible role of psychological or behavioral factors. METHODS. This survey was performed with a validated 43-item self-administered questionnaire eliciting information about back pain history, family characteristics, children's activities, and psychological parameters. All schoolchildren (n = 615), ages 12-17 years, in two secondary schools (Fribourg, Switzerland) were surveyed. The response rate was 98%. RESULTS. Reported lifetime prevalence of back pain was 74%. Lumbar pain was the most frequent localization of pain (69% of back pain). The measured psychological factors were significantly associated with reported nonspecific low back pain and its consequences as well as with sibling history of low back pain. CONCLUSIONS. The study suggests that psychological factors play a role in children's reporting of nonspecific low back pain

Current and retrospective physical and psychological workload was studied in 148 mean, 45-55 years old. The men represented three groups with respect to low back health status: Healthy low back (Group 1, n = 36), intermittent low back pain (LBP) (Group 2, n = 91) and chronic LBP (Group 3, n = 21). The methods used were a self administered questionnaire, a rating scale of perceived exertion, and blind expert assessment built on a classification of job titles. Group 1, the back-healthy subjects, had been less exposed to heavy physical work than subjects with intermittent LBP (Group 2) and chronic LBP subjects (Group 3) through their whole working-career and in their present work (p < or = 0.05, p < or = 0.01). Group 2 tended to be significantly less exposed in their present work than Group 3 (p < or = 0.06). Non-neutral working postures were reported more often in Groups 2 and 3 than in Group 1 (p < or = 0.05, p < or = 0.001). Both groups 2 and 3 perceived present and earlier work to be more strenuous than Group 1, with respect to the low back (p < or = 0.000). Subjects in the healthy low-back group had lower values in the qualitative demand index ('too difficult working tasks' and 'too great responsibility') than subjects in Groups 2 and 3 (p < or = 0.01). This study indicates that more attention should be given to the individual's perception of physical workload

STUDY DESIGN. A population-based survey was undertaken. OBJECTIVES. To describe health care utilization for low back pain (LBP) in a culturally diverse society with universal access to health care; to describe how LBP chronicity influences health care utilization; and to describe how sociocultural and demographic factors and health beliefs influence health care utilization. METHODS. A probability sample of approximately 5,000 Belgian adults stratified by gender, age, social class, and habitat was surveyed by trained interviewers. Information on demographics, health beliefs, frequency of LBP, and health care utilization was elicited. Statistical analysis was conducted by means of univariate and multivariate logistic regression. Analysis was restricted to 2,660 respondents with history of LBP. RESULTS. Of subjects with LBP, 38% reported daily LBP. Sixty-three percent had seen a health professional for the most recent episode; 11% had been on bed rest. Forty-four percent had at sometime undergone radiography; three and a half percent had ever undergone spinal surgery. Eighty-six percent considered themselves in good health. Controlling for LBP frequency, all forms of health care utilization examined were associated with health beliefs. CONCLUSIONS. LBP frequency, health beliefs, and sociocultural factors influence health care behaviors and utilization among adults with a history of LBP in a society with universal access to health care. The association of history of spinal surgery with reports of daily LBP suggests that spinal surgery has failed, at least partly, to relieve LBP

1. While the subject maintained a weak contraction in his finger flexor muscles, holding the metacarpophalangeal joints in 45 deg flexion, test torque pulses were applied which caused rapid finger extension movements and electromyographic (EMG) stretch reflex responses. Before each test pulse the fingers were passively flexed or extended ('post-short' and 'post-long' trials) for about 10 s. The EMG and joint deflection responses in the two types of trial were compared after averaging. 2. In the 'post-long' trials, the EMG reflex response showed a comparative increase in latency, with a reduction of the short-latency (M1) component and an enhancement of the medium-latency (M2) component. 3. The angular deflections were larger, and the turning points of the deflections, which indicated the start of the mechanical reflex responses, occurred later in the 'post-long' trials. These differences were not seen when the torque pulse was immediately preceded by a strong, brief isometric finger flexor contraction in the test position. 4. Immediately following the return to the test position the background finger flexor EMG activity was larger in the 'post-long' trials, a difference which gradually subsided over 15-20 s. A strong, brief contraction in the test position also eliminated this inter-trial difference. 5. The results are interpreted as manifestations of thixotropic after-effects in intra- and extrafusal muscle fibres. It is proposed that the M1 component of the stretch reflex is largely a response to the 'initial burst' of impulses in primary spindle afferents.(ABSTRACT TRUNCATED AT 250 WORDS)

OBJECTIVES. To study the pattern of plasma levels of endotoxin, tumour necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6) and C-reactive protein (CRP) in febrile neutropenic patients and to assess the potential diagnostic value of these analyses. DESIGN. Consecutive prospective study. SETTING. Patients treated at the haematology ward at Danderyd Hospital, Sweden. SUBJECTS. Ninety-four patients with fever and haematological disease entered the study (male/female: 59/35) with 176 febrile episodes. INTERVENTIONS. Blood samples were drawn at days 0, 1, 2 and 6 after onset of fever for analysis of, endotoxin, TNF-alpha, IL-6 and CRP. RESULTS. Infectious aetiology was established in 62.5% of the febrile episodes. Blood cultures showed significant growth in 71/176 (40.3%) febrile episodes. Nonbacteraemic bacterial infections were diagnosed in 34/176 (19.3%) episodes. Endotoxin was detected in plasma in 40% of febrile episodes regardless of aetiology. TNF-alpha was detected in 61% and IL-6 in 94% of all febrile episodes. The initial TNF-alpha and IL-6 levels were significantly higher in patients with Gram-negative bacteraemia than in patients with other causes of fever (P < 0.001). In episodes evaluated as successful after empirical antibiotic treatment, a significant (P < 0.001) decrease in CRP concentrations were found on day 6 after onset of fever. CONCLUSIONS. The sustained, low-grade endotoxaemia and persistently elevated levels of TNF-alpha and IL-6 found in febrile patients may reflect a failing mucosal barrier that allows endogenous bacterial products to reach the circulation. The diagnostic value of endotoxin, TNF-alpha, IL-6 and CRP to discriminate between bacteraemic and nonbacteraemic febrile episodes was very limited. The study supports the present policy of broad, empirical antibiotic treatment in patients with haematological disease and fever

A study population composed of 1,755 children 8-16 years of age were surveyed using a 15-item, self-administered questionnaire. The response rate was 97.7%. The purpose of the survey was to evaluate the possible association between low-back pain and certain social factors and predicaments. Descriptive statistics and logistic regression analysis showed that parental history of treated low-back pain (adjusted odds ratio 2.10; p < 0.001), competitive sports activity (adjusted odds ratio 1.73; p = 0.003), and time spent watching television (adjusted odds ratio 1.23; p = 0.05) significantly increased the risk for low-back pain among children, controlling for the child's age and gender

Intrafascicular recordings of afferent multi-unit activity were obtained from the supraorbital nerve in 40 healthy human volunteers, using tungsten micro-electrodes inserted percutaneously at the eyebrow. Seventy-seven fascicular receptive fields were mapped; their area ranged from 2 to 76 cm2, with a median of 19 cm2. The smallest fields were found in the eyebrow region, and the largest on the scalp. In response to non-painful electrical intradermal stimulation, the conduction velocity of the fastest nerve fibres was calculated to be 40 +/- 2 m s-1 (mean +/- SEM), and the later part of the afferent volley corresponded to a velocity of 20 +/- 1 m s-1. The responses to skin indentation indicated that the density of mechanoreceptive innervation was higher in the lower part of the forehead than in the upper/posterior part of the innervation territory of the nerve. A rapid mechanical tap on the forehead and scalp evoked two major afferent volleys corresponding to the on- and off-phase of the stimulus. Manipulation of hairs resulted not only in dynamic responses to hair movement, but also in a static discharge during sustained hair displacement. When a fascicular field included the eyebrow region, skin stretching during blinking movements evoked distinct afferent activity. Following mechanical and electrical stimuli there were no signs of 'trigeminal antidromic potentials' of the type described in the cat and monkey