Biomedical subjects

E Nordh

Publications and source records attributed to E Nordh.

At least 19 recordsLinked to original sources

PubMed2006

Considerations in evaluating new treatment alternatives following peripheral nerve injuries: a prospective clinical study of methods used to investigate sensory, motor and functional recovery.

The current problem finding reliable and objective methods for evaluating results after peripheral nerve repair is a challenge when introducing new clinical techniques. The aim of this study was to obtain reference material and to evaluate the applicability of different tests used for clinical assessment after peripheral nerve injuries. Fifteen patients with a history of complete median nerve transsection and repair, and 15 healthy volunteers were included. Each subject was investigated using a battery of conventional and new tests for functional, sensory and motor recovery including questionnaires, clinical evaluations, neurophysiological and physiological findings. The results were statistically analysed and comparisons were made within the patient group and between patients and healthy volunteers using a 'per protocol' and an 'intention to treat' approach. Criteria for success were stipulated in order to be able to judge the usefulness of each method. The results showed that 19 of 34 variables, representing six of 16 methods, were not able to fulfil the criteria and were thus questionable for the evaluations of nerve repair in a clinical trial setting. However, 2pd, sensory recovery according to the non-modified British Medical Research Council, sensory neurography, manual muscle test, electromyography, questionnaires (i.e. DASH and the 4 question form) and performance tests (i.e. AMPS and Sollerman's subtests 4 and 8) did fulfil the criteria defined for being useful.

Action Potentials↗

PubMed2006

Head immobilization can impair jaw function.

Findings that jaw-opening/-closing relies on both mandibular and head movements suggest that jaw and neck muscles are jointly activated in jaw function. This study tested the hypothesis that rhythmic jaw activities involve an active repositioning of the head, and that head fixation can impair jaw function. Concomitant mandibular and head-neck movements were recorded during rhythmic jaw activities in 12 healthy adults, with and without fixation of the head. In four participants, the movement recording was combined with simultaneous registration of myoelectric activity in jaw and neck muscles. The results showed neck muscle activity during jaw opening with and without head fixation. Notably, head fixation led to reduced mandibular movements and shorter duration of jaw-opening/-closing cycles. The findings suggest recruitment of neck muscles in jaw activities, and that head fixation can impair jaw function. The results underline the jaw and neck neuromuscular relationship in jaw function.

Adult↗

PubMed2002

Spatiotemporal consistency of human mandibular and head-neck movement trajectories during jaw opening-closing tasks.

Previous studies of spatial and temporal coordination between human mandibular and head-neck movements during single as well as rhythmic jaw opening-closing tasks suggest that these movements are regulated by central nervous commands common for jaw and neck muscles. The present study evaluated the spatiotemporal consistency of concomitant mandibular and head-neck movements during repeated single jaw opening-closing tasks, in short- as well as long-term perspectives and at different speeds. The subjects were seated in an upright position without head support. They were instructed to perform single maximal jaw opening-closing movements, repeated ten times for fast and slow speed, respectively. Recordings were made at two sessions. A wireless optoelectronic technique was used to record three-dimensional mandibular and head-neck movements. The spatiotemporal consistency of repeated movement trajectories of the mandible (both in relation to the head and in space) and of the head-neck was quantitatively assessed by a spatiotemporal index (STI). In addition, mean movement trajectory patterns were compared for speed and recording sessions (expressed as correlation coefficient, r). The results showed relatively small STI (high degree of spatiotemporal consistency) and high r (reproducible trajectory patterns) values, both in short- and long-term perspectives, for concomitant mandibular and head-neck movements. The data were not generally speed related. In conclusion, the present results suggest a high degree of spatiotemporal consistency of the kinematic patterns of mandibular and head-neck movements during jaw opening-closing, in short- as well as long-term perspectives. They also indicate that underlying neural processes are invariant in nature. The results give further support to the notion of a tight functional coupling between the human jaw and the neck motor systems during natural jaw function.

Adult↗

PubMed2000

Temporal coordination between mandibular and head-neck movements during jaw opening-closing tasks in man.

Previous finding of concomitant mandibular and head movements during jaw function suggest a functional relation between the human jaw and neck regions. This study examined the temporal coordination between mandibular and head-neck movements during maximal jaw opening-closing tasks, at fast and slow speed. Twenty-four healthy individuals, median age 25 years, participated in the study. They were seated with firm back support but without head-neck support. Mandibular and head movements were simultaneously monitored by a wireless optoelectronic system for three-dimensional movement recording. The timing of head movement in relation to mandibular movement was estimated at defined time-points (start, peak, end and maximum velocity of movement), and during the entire course of the jaw-opening and jaw-closing phases. The results showed that the head in general started to move simultaneously with or before the mandible, reached the peak position simultaneously with, before or after the mandible, and reached the end position after the mandible. A higher degree of temporal coordination was found for fast speed at the start and the peak positions. The head most often attained maximum velocity after the mandible, and mostly lagged behind the mandible during the entire jaw-opening and -closing phases. These findings support the notion of a functional linkage between the human temporomandibular and craniocervical regions. They suggest that "functional jaw movements" comprise concomitant mandibular and head-neck movements which involve the temporomandibular, the atlanto-occipital and the cervical spine joints, and are caused by jointly activated jaw and neck muscles. It is proposed that these jaw and neck muscle actions, particularly at fast speed, are elicited and synchronized by preprogrammed neural command(s) common to both the jaw and the neck motor systems. From the present results and previous observations of concurrent jaw and head movement during fetal yawning, we suggest that these motor programmes are innate.

Adult↗

PubMed2000

Wireless optoelectronic recordings of mandibular and associated head-neck movements in man: a methodological study.

Human mandibular movements in space are the result of combined motions of the mandible and the head-neck. They can be simultaneously monitored by an optoelectronic recording technique via markers at different locations on the mandible and on the head. Markers can be attached to the teeth or to the facial skin. Mandibular movements relative to the head can be calculated by one- or three-dimensional (1D and 3D, respectively) mathematical compensation for head movements. The present study analysed mandibular and associated head movements during maximal jaw opening-closing tasks in 10 healthy subjects using a wireless 3D optoelectronic movement recording system. The study aimed to: (i) estimate the soft tissue related displacement of skin-attached markers at different locations on the face; (ii) compare 1D with 3D mathematical compensation for associated head movements; (iii) evaluate the influence of marker location on the recorded head and mandibular movement amplitudes; and (iv) compare skin-attached markers with teeth-attached markers with regard to temporal estimates of recorded mandibular and head movements. Markers were attached to the upper and lower incisors and to the skin of the forehead, nose-bridge, nose-tip and chin. Soft tissue related displacement of skin-attached markers varied between locations. The displacement for the chin marker was larger than that of other markers. The least displacement was found for the nose-bridge marker. However, relative to mandibular and head movements, respectively, the displacement of the chin marker was of the same order as that of the nose-bridge marker. The temporal estimates were not significantly affected by displacement of the skin-attached markers. Markers at different locations on the head and the mandible registered different amplitudes. The mandibular movement patterns calculated by 1D and 3D compensation were not comparable. It is concluded that markers attached to the chin and the nose-bridge can be reliably used in temporal analyses of mandibular and head movements during maximal jaw opening-closing. With certain limitations, they are acceptable for spatial analyses. Selection of method of marker attachment, marker location, and method of compensation for associated head movements should be based on the aim of the study.

Adult↗

PubMed2000

Co-ordinated mandibular and head-neck movements during rhythmic jaw activities in man.

Recent observations in man of concomitant mandibular and head movements during single maximal jaw-opening/-closing tasks suggest a close functional relationship between the mandibular and the head-neck motor systems. This study was aimed at further testing of the hypothesis of a functional integration between the human jaw and neck regions. Spatiotemporal characteristics of mandibular and associated head movements were evaluated for 3 different modes of rhythmic jaw activities: self-paced continuous maximal jaw-opening/-closing movements, paced continuous maximal jaw-opening/-closing movements at 50 cycles/minute, and unilateral chewing. Mandibular and head-neck movements were simultaneously recorded in 12 healthy young adults, by means of a wireless opto-electronic system for 3-D movement recordings, with retro-reflective markers attached to the lower (mandible) and upper (head) incisors. The results showed that rhythmic mandibular movements were paralleled by head movements. An initial change in head position (head extension) was seen at the start of the first jaw-movement cycle, and this adjusted head position was retained during the following cycles. In addition to this prevailing head extension, the maximal jaw-opening/-closing cycles were paralleled by head extension-flexion movements, and in general the start of these head movements preceded the start of the mandibular movements. The results support the idea of a functional relationship between the temporomandibular and the cranio-cervical neuromuscular systems. We therefore suggest a new concept for human jaw function, in which "functional jaw movements" are the result of activation of jaw as well as neck muscles, leading to simultaneous movements in the temporomandibular, atlanto-occipital, and cervical spine joints.

Adult↗

PubMed1998

Evaluation of skin- versus teeth-attached markers in wireless optoelectronic recordings of chewing movements in man.

This study evaluated the applicability of skin- and teeth-attached reflex markers fixed to the mandible and the head for optoelectronic recording of chewing movements. Markers were attached to the upper and lower incisors and to the skin on the forehead, the bridge of the nose, the tip of the nose and the chin in seven subjects. Chewing movements were recorded in three dimensions using a high-resolution system for wireless optoelectronic recording. Skin markers were systematically displaced due to skin stretch. The largest displacement was observed for the chin marker, whereas minor displacement was found for markers located on the forehead and the bridge of the nose. In repeated recordings, the smallest intra-individual variation in displacement was found for the marker on the bridge of the nose. In spite of relatively large displacement for the chin marker, the temporal estimates of the mandibular movement were not affected. Teeth markers were found to significantly increase the vertical mouth opening, although the duration of the chewing cycle was unaffected. This indicates an increase in chewing velocity. We suggest that markers located on the bridge of the nose are acceptable for recordings of chewing movements. Skin markers on the chin can be reliably used for temporal analysis. They are also acceptable for spatial analysis if an intra-individual variability of 2 mm is allowed. Teeth-attached markers may significantly influence the natural chewing behavior. Thus, both types of marker systems have advantages as well as disadvantages with regard to the accuracy of the chewing movement analysis. Selection of a marker system should be based on the aims of the study.

Adult↗

PubMed1998

Concomitant mandibular and head-neck movements during jaw opening-closing in man.

To test the hypothesis of a functional relationship between the human mandibular and cranio-cervical motor systems, head-neck movements during voluntary mandibular movements were studied in 10 healthy young adults, using a wireless optoelectronic system for three-dimensional (3D) movement recording. The subjects, unaware of the underlying aim of the study, were instructed to perform maximal jaw opening-closing tasks at fast and slow speed. Movements were quantified as 3D movement amplitudes. A consistent finding in all subjects was parallel and coordinated head-neck movements during both fast and slow jaw opening-closing tasks. Jaw opening was always accompanied by head-neck extension and jaw closing by head-neck flexion. Combined movement and electromyographic recordings showed concomitant neck muscle activity during head-neck movements, indicative of an active repositioning of the head. No differences in 3D movement amplitudes could be seen with respect to speed. The head movement was 50% of the mandibular movement during jaw opening, but significantly smaller (30-40%), during the jaw closing phase. In repeated tests, the 3D movement amplitudes of the concomitant head movements were less variable during slow jaw movement and during the jaw opening phase, than during fast and jaw closing movements, suggesting speed- and phase-related differences in the mechanisms controlling the integrated mandibular and head-neck motor acts. The present results give further support to the concept of a functional trigeminocervical coupling during jaw activities in man.

Adult↗

PubMed1997

Usefulness of pallidotomy in advanced Parkinson's disease.

OBJECTIVE: The combined effect of posteroventral pallidotomy and optimal medical treatment was assessed in 22 patients with levodopa sensitive Parkinson's disease. METHODS: Timed motor tests, video recordings, and computer assisted optoelectronic movement analysis were used for serial hourly assessments performed preoperatively and four and 12 months after operation. Tests were made while patients were on optimal medical therapy. RESULTS: There were no serious adverse events of surgery. Two of the 22 patients could not complete all the tests after operation. The proportion of dyskinesia periods decreased in the 20 patients and there was a proportional increase in normal or fairly normal occasions. "Off" periods were not significantly affected. In 12 of 13 patients with limb dyskinesia this symptom was completely abolished in the contralateral limbs. There was also some degree of improvement axially and ipsilaterally. Tremor was moderately improved contralaterally. Bradykinesia remained unchanged. Results at 12 months follow up were similar to those at four months. CONCLUSION: Pallidotomy produced a pronounced positive effect on dyskinesia and a moderate effect on tremor. Bradykinesia was not affected. Posteroventral pallidotomy may be useful in patients with Parkinson's disease who have severe motor fluctuations and may allow an increase in levodopa dose to alleviate bradykinesia in "off" states.

Adult↗

PubMed1996

Spatial activation maps--bioelectric signals related to 3D recorded movements.

The analysis of multidimensional neurophysiological data poses difficulties for the scientist in understanding the often complex inherent data relations. This is particularly the case when neuromuscular cell discharge parameters are to be related to body segment movement characteristics in freely behaving animals or humans. The understanding of such data is greatly simplified if the recorded data can be visualized in an adequate way, and relevant data relations are thus highlighted. This report describes a rationale for display and qualitative analyses of muscle discharge patterns in relation to three-dimensionally recorded limb or body movements. The method is illustrated by creating spatial activation plots and spatial activation maps of the electromyographic activity in the first interosseal muscle in the human hand, but this rationale for data presentation can be applied to most excitable tissues that are activated in relation to body or limb movements.

Adult↗

PubMed1996

A flexible high-precision video system for digital recording of motor acts through lightweight reflex markers.

This paper describes and evaluates the digital MacReflex system for wireless recording of movements in three dimensions. Up to seven high resolution infra-red sensitive CCD video cameras with electronic shutters register the positions of maximally 40 stroboscopically illuminated retro-reflective tape markers. The system is equipped with real-time video processors for computation of position co-ordinates for the markers and for optimised data transmission and storage. Data are output to any type of computer through a standard serial interface, which also provides possibilities for simultaneous A/D-sampling. Dynamic manipulation of the recorded signals in three-dimensional plots is provided by standard software and transformation and evaluation of recorded data are performed in standard software. The described equipment is found to offer a flexible and easily operated solution for recording of movements with high resolution.

Computer Graphics↗

PubMed1985

Discharge in muscle spindle afferents related to direction of slow precision movements in man.

Single-unit activity was recorded with needle electrodes in eighteen muscle spindle afferents (eleven primaries, seven secondaries) from finger extensor muscles in the radial nerve of awake human subjects. The discharge rate of the afferents was determined during precisely controlled voluntary movements. The subjects performed a standardized visual ramp-and-hold tracking task, which included very slow finger extension and flexion movements (2.5 deg/s) with an amplitude of 20 deg. Throughout the tracking task a constant torque load of small or intermediate size, i.e. less than 30% of maximum voluntary contraction force, opposed finger extension. Altogether, 131 trials were studied. For most units the discharge rate was lower during shortening compared with active position holding, and it was higher during lengthening contractions. Thus, the majority of units responded to phasic stretch during the active movements, although the size of the movement response varied considerably between units and was never large. A few units even exhibited a reversed stretch response pattern. Hence, when estimated from pooled data, movement responses of the unit sample as a whole were small, around 1 impulse/s. The over-all response pattern of an individual afferent during the tracking task was very similar between successive tests. Although the discharge rate of most units increased with the load during movements as well as during position holding, the presence as well as the magnitude of movement responses depended only little on the size of the load. However, a few afferents exhibited a stretch response pattern with small loads and a reversed stretch response pattern with larger loads. In spite of the predominant increase of afferent firing during muscle lengthening there was no systematic modulation of the discharge rate in relation to the joint angle during the active movements, either in the primary or in the secondary afferents. The present findings suggest that human muscle spindles provide information about the occurrence as well as the direction of slow isotonic movements at low velocities in a precision motor task. This is in contrast to the lack of accurate position response which has previously been demonstrated.

Action Potentials↗

PubMed1983

The variability of inter-spike intervals of human spindle afferents in relaxed muscles.

The impulse discharge in single afferent units was recorded in waking human subjects. Tungsten needle electrodes were percutaneously inserted in the left radial nerve, and activity in muscle spindle afferents from the extensor muscles of the forearm were studied while the subjects remained relaxed. Thirty-six spontaneously discharging single units were studied, 16 primaries, 10 secondaries and 10 non-classified. The regularity of afferent discharge and the shape of the inter-spike interval histograms was assessed by off-line statistical analysis of stationary segments of afferent discharge. The mean discharge rate of both primary and secondary afferents was generally low. Secondaries predominantly fired with low variability, whereas primaries showed high as well as low variability, but the median values for the two groups differed significantly. However, the individual unit values of coefficient of variation showed a considerable overlap between the two groups. The size of the coefficient of variation in the human spindle afferents was between that of de-efferented and of intact afferents in decerebrated cats. Determination of the coefficient of variation may therefore help, as a complementary criterion, to differentiate between primary and secondary afferents in man.

Adult↗

PubMed1982

Trigeminal neuralgia as a consequence of circulatory disorders in the infratemporal and pterygopalatine fossae.

An extensive review of the well documented experimental and clinical findings related to trigeminal neuralgia shows, that it is possible to set up an unifying theory for trigeminal neuralgia, which would explain most clinical features of the disease and also would be congruent with several other theories that have previously been presented. Thus, trigeminal neuralgia is proposed to be the result of a combination of predisposing anatomical variations, impaired arterial and venous circulation, and morphological changes in the infratemporal fossa and cavum Meckeli. The process is initiated by disturbances of dental occlusion and mandibular function, resulting in muscular hypertrophy, which finally leads to increased perineural pressure and hypoxia in the nervous tissue. Through a series of related events this results in massive afferent discharges in the trigeminal nerve, which are strong enough to break through an inhibitory gating mechanism in the nucleus caudalis, and which are experienced by the patient as a pain attack. But the tissue hypoxia, which partly has elicited the pain, will finally also be the critically delimiting factor for further signal transmission, thereby stopping the pain attack.

Humans↗

PubMed1982

The absence of position response in spindle afferent units from human finger muscles during accurate position holding.

1. Single unit activity of muscle spindle afferents from finger extensor muscles was recorded in the radial nerve of waking human subjects. The mean discharge rate of the afferent units was determined while the receptor related finger was held at fixed angular positions of the metacarpo-phalangeal joint. 2. During a visual tracking task the subjects had to maintain specified angular positions against a load of constant torque which opposed finger extension. For each unit a comparison was made between the mean discharge rates at two angular positions which differed by 20 deg. Under such isotonic conditions the rates of afferent discharge at the two joint positions did not significantly differ, neither for the whole sample of primary, nor for that of secondary units. This was true, no matter whether the load was small or intermediate. Large loads were not tested. 3. For comparison, the passive position responses of a sample of spindle afferent units from the same muscles were studied when the finger was held in fixed positions while the muscles were voluntarily relaxed. Under these conditions a significant position sensitivity was found for both primary and secondary afferents. The mean values were 0.28 impulses/sec. deg (primaries), and 0.21 impulses/sec. deg (secondaries). 4. The absence of position response during active position holding was interpreted as a manifestation of changes in fusimotor outflow which depended on joint position and were large enough to compensate for changes in muscle length.

Action Potentials↗

PubMed1981

Do spindle afferents monitor joint position in man? A study with active position holding.

The activity of human spindle afferents from finger extensor muscles has been studied during voluntary position holding at two finger positions, to disclose any explicit monitoring of muscle length. The results indicate that, taken as groups, neither primary nor secondary afferents show explicit position responses during active position tracking. Thus any contribution from muscle spindle to position sense must be derived from other components in spindle afferent discharge.

Afferent Pathways↗

PubMed1980

A program for sampling, assessment of stationarity and variability analysis of neuronal spike trains, run under control of a time-sharing system.

A system has been developed for off-line analysis of discharge characteristics of continuously firing nerve cells. The programs, which are mainly written in FORTRAN IV, determine mean firing rates, variability and other parameters of the impulse activity, and construct interspike interval histograms. They are run under time-sharing on a small laboratory computer. To disclose possible non-stationarities in the data all interspike interval samples are analysed with the non-parametric Kolmogorov-Smirnov test. This test is very powerful in detecting any differences between two samples and is still very easy to implement in programming. Raw data and computed statistics are stored in random access data files.

Computers↗

PubMed1979

The responses of afferent fibres from the glabrous skin of the hand during voluntary finger movements in man.

1. Afferent activity of 111 single units from the glabrous skin area was recorded percutaneously in the median nerve of human subjects, using tungsten electrodes. 2. The majority of the units (103) were classified as low-threshold mechano-sensitive units belonging to one of the four categories previously described: rapidly adapting with small receptive fields (RA), rapidly adapting with large receptive fields (PC, presumed Pacinian corpuscle units), slowly adapting with small fields (SA I), and slowly adapting with large fields (SA II). The size of the responses (in number of impulses) to indentation and stretching of the skin was compared with that of the responses elicited during voluntary isotonic finger movements, which avoided trivial excitation of the units by direct touch. 3. All four types of units, and 77% of the single units, were activated by isotonic movements. The decreasing order of responsiveness was PC, SA II, SA I, RA. 4. Almost all responsive units were excited during the dynamic phase of ramp and smooth oscillatory movements. Static responses, on the other hand, occurred only with 50% of the slowly adapting units, corresponding to a third of the total sample (SA II, 81%; SA I, 17%. 5. For all four types of units the dynamic responses to movements were of similar size as the responses to localized skin indentation with a von Frey hair at five times threshold. 6. The results are discussed with regard to the possible implications for kinaesthesia and motor control.

Adult↗