Influence of intrafraction motion on margins for prostate radiotherapy

PURPOSE

To assess the impact of intrafraction intervention on margins for prostate radiotherapy.

METHODS AND MATERIALS

Eleven supine prostate patients with three implanted transponders were studied. The relative transponder positions were monitored for 8 min and combined with previously measured data on prostate position relative to skin marks. Margins were determined for situations of (1) skin-based positioning, and (2) pretreatment transponder positioning. Intratreatment intervention was simulated assuming conditions of (1) continuous tracking, and (2) a 3-mm threshold for position correction.

RESULTS

For skin-based setup without and with inclusion of intrafraction motion, prostate treatments would have required average margins of 8.0, 7.3, and 10.0 mm and 8.2, 10.2, and 12.5 mm, about the left-right, anterior-posterior, and cranial-caudal directions, respectively. Positioning by prostate markers at the start of the treatment fraction reduced these values to 1.8, 5.8, and 7.1 mm, respectively. Interbeam adjustment further reduced margins to an average of 1.4, 2.3, and 1.8 mm. Intrabeam adjustment yielded margins of 1.3, 1.5, and 1.5 mm, respectively.

CONCLUSION

Significant reductions in margins might be achieved by repositioning the patient before each beam, either radiographically or electromagnetically. However, 2 of the 11 patients would have benefited from continuous target tracking and threshold-based intervention.

Accelerated closure of biopsy-type wounds by mechanical stimulation

OBJECTIVE

To determine whether a device designed to provide low-intensity, low-frequency mechanical stimulation improves healing time of acute wounds.

DESIGN

Repeated measures using mechanical stimulation on one side of a rat and sham stimulation on the contralateral side.

SETTING

Academic animal facility.

PARTICIPANTS

Six male Sprague-Dawley rats, approximately 400 g.

INTERVENTION

Mechanical stimulation of 4-mm biopsy wounds in rats was produced through the use of permanent magnets cyclically attracted and repelled by activation of an electromagnet by a square wave generator at a frequency of 1 Hz and a force equivalent to 64 mm Hg pressure.

MAIN OUTCOME MEASURE

Days to complete closure of 4-mm biopsy punch wounds.

MAIN RESULTS

This form of stimulation reduced time to close the biopsy wounds by nearly 50%. Mechanically stimulated wounds closed in 3.8 +/- 1.6 days (mean +/- SD) compared with 6.8 +/- 1.9 days for sham-stimulated wounds (P = .0002).

CONCLUSION

Production of a mechanical stimulation device with a miniaturized controller and power source and trials on humans are needed to determine the efficacy and potential cost savings of such a device in the management of wounds.

Does reaching the back reflect the actual internal rotation of the shoulder?

To clarify the relationship between the vertebral level reached by the thumb and the internal rotation angle of the humerus, 7 shoulders in healthy volunteers were examined by use of an electromagnetic tracking device. Measurements were repeated in the hanging-arm position with the thumb pointing anteriorly and at the buttock, sacrum, and each vertebral level up to T6. From the hanging-arm position to the buttock, 54.3% of internal rotation occurred (mean, 39.8 degrees ), and from the buttock to the sacrum, 11.7% occurred (mean, 8.6 degrees ). In total, 66% of internal rotation occurred from the hanging-arm position to the sacrum. Above the sacrum, the contribution of elbow flexion to the level of the vertebral spine became much greater, and internal rotation of the shoulder did not change significantly above the T12 level. We recommend that the level of the thumb below the buttock be subdivided for more accurate assessment of internal rotation.

[Effect of complex rehabilitation by physical factors (therapeutic mud, waves of millimeter range) on the indices of inflammation process and immune status in patients with traumas of peripheral nervous system]

82 patients with traumas of peripheral nervous trunks (middle, ulnar, radial, tibular and tibial nerves) were investigated, including 44 persons with neuroapraxia of those trunks and 38 with axonotmesis. It was established that the patients with traumas of peripheral nervous trunks showed the presence of inflammatory process and sensitization of the body which was exposed in the reaction of precipitation at C-reactive protein with the increase of the content of serum glycoides and total nonspecific immunuglobulin E in blood serum. The investigated patients showed also decrease in nonspecific resistance of organism and change in immune status. All the above-referred shifts were more expressed at axonotmesis of peripheral nervous trunks. Rehabilitation with the use of Kumisi therapeutic mud and electro magneto field of millimeter range resulted decrease of inflammation process and body sensitization in patients with traumas of peripheral nervous trunks almost to disappearance of inflammation process and body sensitization. Such rehabilitation increased nonspecific resistance, normalized the indices of immune reactivity. The above-referred positive shifts were comparatively well expressed at neuroapraxia of peripheral nervous trunks.

Orthogonal-Coil RF Probe for Implantable Passive Sensors

A versatile orthogonal-coil radio frequency (RF) probe suitable for detecting the resonant frequency of miniature implantable passive sensors has been designed and tested. The probe sensitivity has been tested using printed-circuit spiral inductors of various sizes (3-15 mm) in series with discrete surface-mount capacitors designed to resonate over a range of frequencies (50-200 MHz). Close agreement between theoretical calculations and experimental results has been obtained. An equation is derived for transmit/receive (T/R) isolation that agrees with experimental measurements over the frequency range 1-500 MHz. The probe includes an additional coil to compensate for the effect of eddy currents in the human body on the probe. T/R isolation of at least 90 dB over the frequency range 1-100 MHz can be achieved when the probe is placed in close proximity to the human body.

Diaphragmatic function in advanced Duchenne muscular dystrophy

The aim of this study was to assess diaphragm electrical activation and diaphragm strength in patients with advanced Duchenne muscular dystrophy during resting conditions. Eight patients with advanced Duchenne muscular dystrophy (age of 25 +/- 2 years) were studied during tidal breathing, maximal inspiratory capacity, maximal sniff inhalations, and magnetic stimulation of the phrenic nerves. Six patients were prescribed home mechanical ventilation (five non-invasive and one tracheotomy). Transdiaphragmatic pressure and diaphragm electrical activation were measured using an esophageal catheter. During tidal breathing (tidal volume 198 +/- 83 ml, breathing frequency 25 +/- 7), inspiratory diaphragm electrical activation was clearly detectable in seven out of eight patients and was 12 +/- 7 times above the noise level, and represented 45 +/- 19% of the maximum diaphragm electrical activation. Mean inspiratory transdiaphragmatic pressure during tidal breathing was 1.5 +/- 1.2 cmH2O, and during maximal sniff was 7.6 +/- 3.6 cmH2O. Twitch transdiaphragmatic pressure deflections could not be detected. This study shows that despite near complete loss of diaphragm strength in advanced Duchenne muscular dystrophy, diaphragm electrical activation measured with an esophageal electrode array remains clearly detectable in all but one patient.

Low-resolution electromagnetic tomography and treatment response in obsessive-compulsive disorder

We investigated whether findings from pretreatment low-resolution electromagnetic tomography (LORETA) predicted response to drug treatment in patients with obsessive-compulsive disorder (OCD). The 3D intra-cerebral distribution of neuronal electrical activity from the scalp-recorded potential distribution of 17 drug-free patients with OCD was assessed with LORETA. They were treated with antidepressants in the maximum tolerated doses for at least 12 wk. Individuals were considered to be treatment responders if they displayed a reduction of at least 35% on the initial YBOCS scores and had a final CGI score of 1 or 2. The SPM-99 t test for independent samples was employed to compare, voxel-by-voxel, the brain electrical activities of responders (n = 10) and non-responders (n = 7). Responders exhibited significantly lower activities in beta band in the rostral anterior cingulate [Brodmann's area (BA) 24 and 32] (p = 0.002) and the medial frontal gyrus (BA 10) (p = 0.002), suggesting that a distinctive pattern of activity within the medial surface of the frontal lobe predicts therapeutic response in OCD.

Correlating motor performance with surgical error in laparoscopic cholecystectomy

BACKGROUND

Analysis of motor performance in minimally invasive surgery (MIS) is a new field with applications in surgical training, surgical simulators, and robotics. Force/torque and derivatives of tool tip position (velocity, acceleration, and jerk) are examples of measures of motor performance (MMPs). Few studies have measured MMPs or have correlated MMPs with surgical performance during MIS on humans. The objectives of this study were to determine the feasibility of a novel multimodal system to quantify MMPs in laparoscopic cholecystectomy and to attempt to correlate MMPs with the magnitude of error as a measure of surgical performance.

METHODS

Novice and expert surgeons performed laparoscopic cholecystectomies in two groups of three patients each. MMPs were obtained using a combination of optical and electromagnetic tool tip tracking and a force/torque sensor on a modified Maryland dissector. Error scores for laparoscopic cholecystectomy were calculated using a previously validated system. Novice and expert measurements were compared, and correlations were made between error scores and MMPs.

RESULTS

Error scores were similar between novices and experts. Novice surgeons had a significantly greater mean velocity (566 +/- 83 vs 85 +/- 32 mm/s, p = 0.006) and acceleration (2,600 +/- 760 vs 440 +/- 174 mm/s2, p = 0.050) compared to expert surgeons. Force (16.5 +/- 4.6 vs 18.3 +/- 6.0 N, p = 0.829), position (121 +/- 25 vs 135 +/- 72 mm, p = 0.863), and jerk (19,600 +/- 7,410 vs 2,430 +/- 367 mm/s3, p = 0.138) were similar between groups. A positive correlation was found in novice surgeons between error score and jerk (Pearson correlation, 0.999; p = 0.035).

CONCLUSIONS

It is feasible to quantify MMPs in laparoscopic cholecystectomy. Novice and expert surgeons can be differentiated by MMPs; moreover, there may be a positive correlation between jerk and error score in novice surgeons.

Dynamics and directionality of the vestibulo-collic reflex (VCR) in mice

The vestibulo-collic reflex (VCR) stabilizes the head in space by excitation of neck muscles that oppose head rotation. Recently, the mouse vestibulo-ocular reflex (VOR) has been characterized so that genetic manipulations of the vestibular system can be examined. We have characterized the dynamics and directionality of the VCR in mice restrained at the neck so that studies of vestibular system genetics may include comparisons to normal VCR in addition to VOR. Head rotations were measured in darkness with a three-dimensional search coil system during whole body rotations. The VCR in four C57BL/6 mice was present in pitch, roll, and yaw directions with an overall average gain of 0.28. Phase was accurately compensatory to oppose head rotation across a wide range of frequencies from 0.02 Hz to 2.0 Hz. Compensatory head rotations were greatest in the direction opposing the applied stimulus and weak or absent in other directions. Constant velocity rotations about horizontal axes elicited head velocity modulation and bias similar to that observed in the VOR. We conclude that the VCR of mice is similar to that in other mammals.

Effect of object transport on grasp coordination in multiple system atrophy

We examined the effects of the parkinsonian variant of multiple-system atrophy (MSA-P) on grasp and forward transport and release of an object. Twelve patients with MSA-P and 10 age-matched control subjects performed the task with each of three object weights (200, 400, 800 gm). Subjects moved at a self-selected pace using a precision grip. The grip (normal) and load (tangential) forces and the object position were recorded. Results indicate subjects with MSA-P have temporal and force coordination deficits. Temporal delays were seen in all subjects with MSA-P, leading to prolonged overall movement times compared to control subjects. These delays occurred throughout the task, with significantly longer transport phases and delays releasing the object. Despite demonstrating an appropriate anticipatory scaling of forces, with increasing grip and load forces for heavier weights, force coordination was compromised in subjects with MSA-P. These subjects generated significant negative load forces prior to transporting the object. In addition, during the transport phase, subjects with MSA-P generated highly variable grip forces. Overall, the results indicate that subjects with MSA-P demonstrate bradykinesia and difficulty coordinating components of an object transport task.

Intra- and intersubject reliability of abductor pollicis brevis muscle motor map characteristics with transcranial magnetic stimulation

OBJECTIVE

To determine consistency in motor maps of the abductor pollicis brevis (APB) muscle using transcranial magnetic stimulation (TMS) with conventional and close-spaced surface electrode recording placements.

DESIGN

Nonrandom convenience sample.

SETTING

TMS laboratory.

PARTICIPANTS

Eleven participants without any known neurologic disorders.

INTERVENTIONS

The left hemisphere of right-hand-dominant subjects was mapped using TMS at each of 2 sessions, separated by 1 to 8 weeks.

MAIN OUTCOME MEASURES

Measurements at each session included the resting motor threshold, active site locations and average motor response amplitude for active sites, normalized map volume, and center of gravity (COG) for both electrode array configurations.

RESULTS

The normalized map volume was larger for the conventional electrode placement than for the close electrode placement (4.23 cm2 vs 3.44 cm2, P=.010). Resting motor threshold was higher for the close-spaced than for the conventional-spaced electrodes (48.36% vs 46.59%, P=.028). No statistical difference was found between sessions and within electrode placements for the normalized map volume, for resting motor threshold, or for the mean motor amplitude of the most active site for each map. No statistical difference was observed for the COG distance between electrode placements.

CONCLUSIONS

This study revealed differences between close-spaced and conventional-spaced surface electrode placement for TMS motor map volumes and for resting motor thresholds. The motor maps for the APB muscle were reliably reproducible between sessions for each electrode array.

Behavioral effects on rats of high strength magnetic fields generated by a resistive electromagnet

It has been reported previously that exposure to static high magnetic fields of 7 T or above in superconducting magnets has behavioral effects on rats. In particular, magnetic field exposure acutely but transiently suppressed rearing and induced walking in tight circles; the direction of circular locomotion was dependent on the rats' orientation within the magnet. Furthermore, when magnet exposure was paired with consumption of a palatable, novel solution, rats acquired a persistent taste aversion. In order to confirm these results under more controlled conditions, we exposed rats to static magnetic fields of 4 to 19.4 T in a 189 mm bore, 20 T resistive magnet. By using a resistive magnet, field strengths could be arbitrary varied from -19.4 to 19.4 T within the same bore. Rearing was suppressed after exposure to 4 T and above; circling was observed after 7 T and above. Conditioned taste aversion was acquired after 14 T and above. The effects of the magnetic fields were dependent on orientation. Exposure to +14 T induced counter-clockwise circling, while exposure to -14 T induced clockwise circling. Exposure with the rostral-caudal axis of the rat perpendicular to the magnetic field produced an attenuated behavioral response compared to exposure with the rostral-caudal axis parallel to the field. These results in a single resistive magnet confirm and extend our earlier findings using multiple superconducting magnets. They demonstrate that the behavioral effects of exposure within large magnets are dependent on the magnetic field, and not on non-magnetic properties of the machinery. Finally, the effects of exposure to 4 T are clinically relevant, as 4 T magnetic fields are commonly used in functional MRI assays.

An Inverse Methodology for High-Frequency RF Coil Design for MRI With De-emphasized$B _1$Fields

An inverse methodology for the design of biologically loaded radio-frequency (RF) coils for magnetic resonance imaging applications is described. Free space time-harmonic electromagnetic Green's functions and de-emphasized B1 target fields are used to calculate the current density on the coil cylinder. In theory, with the B1 field de-emphasized in the middle of the RF transverse plane, the calculated current distribution can generate an internal magnetic field that can reduce the central overemphasis effect caused by field/tissue interactions at high frequencies. The current distribution of a head coil operating at 4 T (170 MHz) is calculated using an inverse methodology with de-emphasized B1 target fields. An in-house finite-difference time-domain routine is employed to evaluate B1 field and signal intensity inside a homogenous cylindrical phantom and then a complete human head model. A comparison with a conventional RF birdcage coil is carried out and demonstrates that this method can help in decreasing the normal bright region caused by field/tissue interactions in head images at 170 MHz and higher field strengths.

Vestibulo-collic reflex (VCR) in mice

The vestibulo-collic reflex (VCR) attempts to stabilize head position in space during motion of the body. Similar to the better-studied vestibulo-ocular reflex, the VCR is subserved by relatively direct, as well as indirect pathways linking vestibular nerve activity to cervical motor neurons. We measured the VCR using an electromagnetic technique often employed to measure eye movements; we attached a loop of wire (head coil) to an animal's head using an adhesive; then the animal was gently restrained with its head free to move within an electromagnetic field, and was subjected to sinusoidal (0.5-3 Hz) or abrupt angular acceleration (peak velocity approximately 200 degrees/s). Head rotation opposite in direction to body rotation was assumed to be driven by the VCR. To confirm that the compensatory head movements were in fact vestibular in origin, we plugged the horizontal canal unilaterally and then retested the animals 2, 8 and 15 days after the lesion. Two days after surgery, the putative VCR was almost absent in response to abrupt or sinusoidal rotations. Recovery commenced by day 8 and was nearly complete by day 15. We conclude that the compensatory head movements are vestibular in origin produced by the VCR. Similar to other species, there are robust compensatory mechanisms that restore the VCR following peripheral lesions.

Microwave detection at 110 Ghz by nanowires with broken symmetry

By using arrays of nanowires with intentionally broken symmetry, we were able to detect microwaves up to 110 GHz at room temperature. This is, to the best of our knowledge, the highest speed that has been demonstrated in different types of novel electronic nanostructures to date. Our experiments showed a rather stable detection sensitivity over a broad frequency range from 100 MHz to 110 GHz. The novel working principle enabled the nanowires to detect microwaves efficiently without a dc bias. In principle, the need for only one high-resolution lithography step and the planar architecture allow an arbitrary number of nanowires to be made by folding a linear array as many times as required over a large area, for example, a whole wafer. Our experiment on 18 parallel nanowires showed a sensitivity of approximately 75 mV dc output/mW of nominal input power of the 110 GHz signal, even though only about 0.4% of the rf power was effectively applied to the structure because of an impedance mismatch. Because this array of nanowires operates simultaneously, low detection noise was achieved, allowing us to detect -25 dBm 110 GHz microwaves at zero bias with a standard setup.

Microwave transport in metallic single-walled carbon nanotubes

The dynamical conductance of electrically contacted single-walled carbon nanotubes is measured from dc to 10 GHz as a function of source-drain voltage in both the low-field and high-field limits. The ac conductance of the nanotube itself is found to be equal to the dc conductance over the frequency range studied for tubes in both the ballistic and diffusive limit. This clearly demonstrates that nanotubes can carry high-frequency currents at least as well as dc currents over a wide range of operating conditions. Although a detailed theoretical explanation is still lacking, we present a phenomenological model of the ac impedance of a carbon nanotube in the presence of scattering that is consistent with these results.

Design and application of an assessment protocol for electromagnetic tracking systems

This paper defines a simple protocol for competitive and quantified evaluation of electromagnetic tracking systems such as the NDI Aurora (A) and Ascension microBIRD with dipole transmitter (B). It establishes new methods and a new phantom design which assesses the reproducibility and allows comparability with different tracking systems in a consistent environment. A machined base plate was designed and manufactured in which a 50 mm grid of holes was precisely drilled for position measurements. In the center a circle of 32 equispaced holes enables the accurate measurement of rotation. The sensors can be clamped in a small mount which fits into pairs of grid holes on the base plate. Relative positional/orientational errors are found by subtracting the known distances/ rotations between the machined locations from the differences of the mean observed positions/ rotation. To measure the influence of metallic objects we inserted rods made of steel (SST 303, SST 416), aluminum, and bronze into the sensitive volume between sensor and emitter. We calculated the fiducial registration error and fiducial location error with a standard stylus calibration for both tracking systems and assessed two different methods of stylus calibration. The positional jitter amounted to 0.14 mm(A) and 0.08 mm(B). A relative positional error of 0.96 mm +/- 0.68 mm, range -0.06 mm; 2.23 mm(A) and 1.14 mm +/- 0.78 mm, range -3.72 mm; 1.57 mm(B) for a given distance of 50 mm was found. The relative rotation error was found to be 0.51 degrees (A)/0.04 degrees (B). The most relevant distortion caused by metallic objects results from SST 416. The maximum error 4.2 mm(A)/ > or = 100 mm(B) occurs when the rod is close to the sensor(20 mm). While (B) is more sensitive with respect to metallic objects, (A) is less accurate concerning orientation measurements. (B) showed a systematic error when distances are calculated.

[A new method for the treatment of depression: repetitive transcranial magnetic stimulation]

Recent data suggest that repetitive transcranial magnetic stimulation (rTMS) is effective in treating depressive symptoms to a lesser extent compared with classical electroconvulsive therapy. However, rTMS represents an economical and well tolerable procedure in relation to the expenditure of electroconvulsive therapy with anaesthesia. Usually, rTMS is applicated as an add-on-therapy accompanying psychopharmacological treatment. So far, it has predominantly been used for patients with long-standing and so called treatment-refractory symptoms. However, even in the early phase of a depressive episode rTMS would be possibly more effective. In many cases, the standard procedure-application of up to 10 rTMS-sessions will not be enough to produce therapeutic benefit. Therefore rTMS series including up to 20 sessions are recommended. Long-term studies are needed to clarify the role of rTMS for relapse prevention and to determine the optimal frequency and duration of rTMS in such an indication. Although numerous results of newer studies suggest a moderate antidepressive effect of rTMS, its application in daily clinical routine practice cannot be recommended yet. Larger, accurate designed and controlled studies, especially involving patients of old age, are needed to evaluate the true tolerability and effectiveness of rTMS as a new treatment option for depressive symptoms.

Effectiveness of frequency-modulated electromagnetic neural stimulation in the treatment of painful diabetic neuropathy

AIMS/HYPOTHESIS

The largely unsatisfactory results reported for the pharmacological treatment of diabetic neuropathy has spurred the search for alternative therapies. The aim of this study was to evaluate the efficacy of frequency-modulated electromagnetic neural stimulation (FREMS) as a novel treatment for painful diabetic neuropathy.

METHODS

Patients (n=31) with painful neuropathy associated with decreased nerve conduction velocity (<40 m/s) and increased vibration perception threshold (>25 V) were enrolled in a randomised, double-blind, crossover study designed to compare the effects of FREMS with those of placebo. Each patient received two series of ten treatments of either FREMS or placebo in random sequence, with each series lasting no more than 3 weeks. The primary efficacy end point was the change in pain measured by a visual analogue scale (VAS).

RESULTS

FREMS induced a significant reduction in daytime and night-time VAS pain score (all p<0.02). Furthermore, FREMS induced a significant increase in sensory tactile perception, as assessed by monofilament; a decrease in foot vibration perception threshold, as measured by a biothesiometer; and an increase in motor nerve conduction velocity (all p<0.01). No significant changes were observed after placebo. Comparison of measurements at the 4-month follow-up with those at baseline revealed that a significant benefit persisted for all measures that showed an improvement at the end of treatment, with an additional improvement in quality of life evaluated by the Short Form-36 questionnaire (all p<0.05). No significant side effects were recorded during the study.

CONCLUSIONS/INTERPRETATION

FREMS is a safe and effective therapy for neuropathic pain in patients with diabetes and is able to modify some parameters of peripheral nerve function.

Influence of orofacial dysfunctions on spatial and temporal dimensions of swallowing movements

BACKGROUND AND AIM

Tongue dysfunctions are of etiologic significance for the development of malocclusions and speech disorders. Electromagnetic articulography is a means of recording orofacial movements. The aim of this study was therefore to analyze differences in the spatial and temporal sequence of swallowing movements under the influence of lip and tongue dysfunctions in order to develop new means of objectifying the diagnosis of such a dysfunction.

PATIENTS AND METHOD

Thirty-one subjects were monitored during reflex swallowing and while swallowing 20 ml of water. All probands also underwent evaluation by a speech pathologist as well as palatography. The entire cohort was then divided into a viscerally and a somatically swallowing group, and the movement sequences were analyzed with reference to spatial and temporal parameters.

RESULTS

The temporal parameters revealed fewer significant differences than the spatial parameters. Most differences were recorded for the section between palate separation point and end of swallowing. Specific spatial or temporal variables revealing a maximum number of differences between the two groups were found for each tongue region. Swallowing water revealed notably more significant intergroup differences. The most suitable variables during the swallowing of water were the maximum distance of tongue-palate contact and the distance or time interval between palate separation point and end of swallowing.

CONCLUSION

The analysis of swallowing movements by electromagnetic articulography offers opportunities to evaluate tongue dysfunctions. The most suitable combination of variables was found for each of the regions investigated. Spatial analysis of the movement pattern seems to be the most reliable method.

In vitro exposure apparatus for ELF magnetic fields

For in vitro studies on the effect of extremely low frequency (ELF) magnetic field exposures in different laboratories, a programmable, high precision exposure system enabling blinded exposures has been developed and fully characterized. It is based on two shielded 4 coil systems that fit inside a commercial incubator. The volume of uniform B field exposure with 1% field tolerance is 50% larger compared to a Merrit 4 coil system with the same coil volume. The uncertainties for the applied magnetic fields have been specified to be less than 4%. The computer controlled apparatus allows signal waveforms that are composed of several harmonics, blind protocols, monitoring of exposure and environmental conditions and the application of B fields up to 3.6 mT root-mean-square amplitude. Sources of artifacts have been characterized: sham isolation >43 dB, parasitic incident E fields <1 V/m, no recognizable temperature differences in the media for exposure or sham state, and vibrations of the mechanically decoupled dish holder <0.1 m/s(2) (= 0.01 g), which is only twice the sham acceleration background level produced by the incubator and fan vibrations.

Variation in the cervical range of motion over time measured by the "flock of birds" electromagnetic tracking system

STUDY DESIGN

Observational longitudinal study.

OBJECTIVE

To establish the normal variation over time for active and passive cervical range of motion (ROM) measured with the Flock of Birds electromagnetic tracking system (FOB).

SUMMARY OF BACKGROUND DATA

Data about normal variation of cervical ROM over time are scarce but important for the interpretation of study results.

METHODS

Forty-eight subjects without a manifest dysfunction in neck and shoulder region (asymptomatic group) and 58 subjects with a dysfunction in the neck and shoulder region (symptomatic group) participated in this study. Cervical active and passive ROM was assessed in three different sessions 6 weeks apart. The following movements were measured: flexion-extension, lateral bending, and axial rotation in neutral, flexed, and extended position.

RESULTS

A wide range of variation of active and passive cervical ROM was found at the 6- and 12-week measurement in the asymptomatic group as well as in the symptomatic group. Highest variation was found during passive ROM testing as compared with active ROM testing. The symptomatic group showed larger variation than the asymptomatic group.

CONCLUSIONS

Cervical range of motion varies considerably over time. This variation should be taken into account when results of therapeutic trials with respect to cervical ROM are interpreted.