Active Wrist Research Articles

Comparative Analysis of Intramedullary Nail Fixation Versus Casting for Treatment of Distal Radius Fractures

Intramedullary fixation is one treatment option for distal radius fractures. Our purpose was to compare the outcomes of intramedullary nailing to those of casting for these injuries. From 2006 to 2009, we reviewed 63 adult patients with isolated distal radius fractures. Thirty-one patients had surgical fixation with an intramedullary device (IMN group) within 4 weeks of the injury, and 32 (cast group) had casting as definitive treatment of the fracture. Clinical outcomes (grip strength; Disabilities of the Arm, Shoulder, and Hand scores; active wrist range of motion; and complications) and radiographic indices (radial inclination, radial height, ulnar variance, and tilt) of both groups were analyzed for the 1-, 2-, 4-, 6-, and 12-month follow-up periods. The flexion-extension arc was significantly higher in the IMN group than in the cast group at 2-, 6-, and 12-month follow-up. The IMN group exhibited significantly greater grip strength and lower DASH scores throughout the follow-up period. At final follow-up, all radiographic indices were significantly better in the IMN group than in the cast group. There was no significant difference between the initial reduction to final position in the IMN group, but the cast group showed an increase in ulnar variance and a significant change in dorsal-volar tilt. In addition, the cast group experienced more clinical complications in the delayed period compared to the IMN group. Intramedullary nail fixation, as compared to casting, results in less functional disability, not only in the early postoperative period but also up to a year after treatment. On the basis of our data, intramedullary fixation should be considered for patients with unstable extra-articular or simple intra-articular distal radius fractures.

Scientific study of the extent of transverse movement of the median nerve at the wrist during active wrist extension in static positions of the upper limb tension test one

Objective. Longitudinal glide of the median nerve is affected in typical entrapment neuropathies such as carpal tunnel syndrome. The upper limb tension test one (ULTT1) is used by clinicians to assess patients’ responses to passive movements that affect the median nerve. ULTT1 is thought to mainly assess the longitudinal glide of the median nerve; however, transverse glide of the nerve at the wrist may be a more sensitive measure of an entrapment neuropathy. Method. Sixteen wrists of four male and 11 female healthy volunteers were studied with ultrasound imaging in this small original study. Images were collected in eight different combinations of shoulder, elbow and forearm posture. In each posture the wrist was moved from full flexion to 30° of extension. Results Nerve excursion from full wrist flexion to 30° of extension was mainly in a radio-dorsal direction. It ranged from a minimum of 1.8 mm (SD ± 2.0 mm) up to 3.57 mm (SD ± 1.86 mm) of transverse movement, and 0.22 mm (SD ± 0.59 mm) of volar movement to 0.96 mm (SD ± 0.76 mm) of dorsal movement. In all eight of the positions tested, forearm supination led to greater transverse movement of the nerve at the wrist. Conclusions Transverse movement of the median nerve is most marked with forearm supination, irrespective of other changes in the kinetic chain. The nerve moves dorsally in all movements except when the forearm flexors are off-loaded in elbow extension and elbow flexion. These findings confirm the transverse movement of the median nerve at the wrist, during active wrist extension within positions of the ULTT, but that the shoulder and elbow position have little impact on the degree of movement.

Prophylactic effect of hot pack on symptoms of eccentric exercise-induced muscle damage of the wrist extensors

This study investigated whether hot pack treatment could provide prophylactic effects on muscle damage induced by eccentric exercise of the wrist extensors. Twenty-eight healthy men (age 21±1 years, weight 65±16 kg, height 171±6 cm) were randomly placed into hot pack (n = 14) and control (n = 14) groups. All participants performed an exercise consisting of 300 maximal eccentric contractions of the wrist extensors of the non-dominant arm using an isokinetic dynamometer. A hot pack was applied for 20 min to the wrist extensors of the exercised arm before the exercise for the hot pack group. The control group received no treatment before the exercise. Measured variables included pain intensity assessed by a visual analogue scale and a modified Likert's scale, cold thermal pain threshold, pressure pain threshold (PPT), range of motion in active wrist flexion (ROM-AF) and extension (ROM-AE), range of motion in passive wrist flexion (ROM-PF) and extension (ROM-PE), grip strength, and wrist extension strength. Changes in these variables before, immediately after, and 1 to 8 days following the exercise were compared between groups by a two-way repeated measures ANOVA. All outcome measures from both groups (except for the cold thermal pain threshold of the hot pack group) demonstrated a significant change within the first 2–3 days following exercise. Significant differences between groups were only found at a single point in time for PPT, ROM-PF, ROM-PE and ROM-AE, and the changes were smaller for the hot pack group in comparison to the control group. These results suggest that the prophylactic effects of hot pack treatment on eccentric exercise-induced muscle damage of the wrist extensors are limited.

Rise rate and timing variability of surface electromyographic activity during rhythmic drumming movements in the world’s fastest drummer

The winner of an international contest to find the world’s fastest drummer (WFD) can perform repetitive wrist tapping movements with one hand using a handheld drumstick at 10 Hz, much faster than the maximum tapping frequency of 5–7 Hz in the general population. The muscle activity facilitating this improved performance, however, has only recently been explored. The present study investigated the rise rate and timing variability of surface electromyographic (EMG) activity of wrist flexor/extensor muscles in the WFD, and compared them with those in two control groups: non-drummers (NDs) and ordinary drummers (ODs). The WFD showed more rapid EMG amplitude rise, earlier decline of EMG activity, and more stable muscle activation time than the NDs and ODs. In addition, there was a significant correlation between the EMG rise rate and the duration of drum training in the group of drummers (i.e., ODs and WFD). These results indicate that the 10-Hz performance of the WFD was achieved by a ‘sharper’ and ‘less noisy’ burst pattern of wrist muscles, and that drum training would have the effect to increase the speed of development of muscle tension.

Duty periods with early start times restrict the amount of sleep obtained by short-haul airline pilots

Most of the research related to human fatigue in the aviation industry has focussed on long-haul pilots, but short-haul pilots also experience elevated levels of fatigue. The aim of this study was to examine the impact of early start times on the amount of sleep obtained prior to duty and on fatigue levels at the start of duty. Seventy short-haul pilots collected data regarding their duty schedule and sleep/wake behaviour for at least two weeks. Data were collected using self-report duty/sleep diaries and wrist activity monitors. Mixed-effects regression analyses were used to examine the effects of duty start time (04:00–10:00 h) on (i) the total amount of sleep obtained in the 12 h prior to the start of duty and (ii) self-rated fatigue level at the start of duty. Both analyses indicated significant main effects of duty start time. In particular, the amount of sleep obtained in the 12 h prior to duty was lowest for duty periods that commenced between 04:00 and 05:00 h (i.e. 5.4 h), and greatest for duty periods that commenced between 09:00 and 10:00 h (i.e. 6.6 h). These data indicate that approximately 15 min of sleep is lost for every hour that the start of duty is advanced prior to 09:00 h. In addition, self-rated fatigue at the start of duty was highest for duty periods that commenced between 04:00 and 05:00 h, and lowest for duty periods that commenced between 09:00 and 10:00 h. Airlines should implement a fatigue risk management system (FRMS) for short-haul pilots required to work early-morning shifts. One component of the FRMS should be focussed on the production of ‘fatigue-friendly’ rosters. A second component of the FRMS should be focussed on training pilots to optimise sleep opportunities, to identify circumstances where the likelihood of fatigue is elevated, and to manage the risks associated with fatigue-related impairment.

Effect of Partial Wrist Denervation on Wrist Kinesthesia: Wrist Denervation Does Not Impair Proprioception

To evaluate the potential effect of partial wrist denervation on wrist kinesthesia, we hypothesized that anesthetizing the anterior interosseous nerve and the posterior interosseous nerve does not impair the kinesthesia. We performed a double-blinded, prospective, randomized study on 80 healthy volunteers (20-54 y old) to compare the ability to detect active and passive wrist movement in 2 conditions. The test group received an anesthetic block of the anterior and posterior interosseous nerves, and the control group subjects received an injection of saline. The kinesthesia of the 2 groups was then tested in 2 conditions by measuring the error in an active and passive wrist repositioning task. Results were analyzed using a repeated measures analysis of variance. In both active and passive conditions, there was no difference in the repositioning errors between the test group and the control group. Our results show that kinesthesia is not impaired by blocking the anterior and posterior interosseous nerves. These findings are consistent for both active and passive motion. The study gives strong evidence that partial denervation does not impair wrist kinesthesia. However, because only kinesthesia was studied, we cannot conclude that partial denervation is a totally safe procedure for all aspects of proprioception. Therapeutic I.

MRI and ultrasound versus conventional measures of disease activity and structural damage in evaluating treatment efficacy in JIA. Do these imaging techniques have an additional value?

Methods patients with JIA and active wrist arthritis who started receiving a second line therapy (DMARDs or biological agent) at the study Unit between 2008 and 2010 were enrolled in the study. The clinically more affected wrist was studied with MRI (1.5 T), US and conventional radiography (CR), coupled with standard clinical assessment at the study enrollment and after 1 year. Patients were characterized according to the pACR response criteria, and to the current criteria for inactive disease.

Wearable wrist activity monitor as an indicator of functional hand use in children with cerebral palsy

The article by Howcroft et al.1 poses interesting questions regarding clinical measurement: what type of variables are measured during patient management, how are they measured, and the meaning of the information gained in the context of patient management. The sensor developed by Howcroft et al.1 aims to quantify typical hand function in children with cerebral palsy in everyday contexts such as home, school, and during play. Considering the availability of valid and reliable clinician-administered instruments that evaluate hand function (e.g. the Assisting Hand Assessment),2 some would argue that this use of complex technology may not be warranted. However, there is an increasing body of evidence regarding the need to evaluate patients in their own environment, outside the clinical setting. According to the International Classification of Functioning, Disability and Health,3 the ability to perform day-to-day tasks is defined as ‘activity’. Difficulties in performing these tasks are termed activity limitations. Activities can be evaluated using two methods. First, capacity describes an individual’s ability to undertake a task in a standardized environment, and is usually evaluated by a clinician observing a patient performing a task in a standardized, clinical environment. Consequently, it is not known whether these abilities can be transferred into day-to-day tasks undertaken by patients in their own, more unpredictable environment.3 In contrast, performance describes what individuals do in their own environment. This type of measure provides clinicians with information on whether the treatment effects are carried over into everyday situations. This valuable information is necessary for treatment planning, and was addressed in the current study using custom-designed wearable hand monitors. Thus, the information gained from the wearable monitors can be considered to address performance variables. Howcroft et al.1 also demonstrate the complexities which are associated with applying new technologies to patient measurement. Systems designed for use on adults are often not suitable to be applied to paediatric populations because of differences in the size of limbs and frequency of movements.4 Specialist teams, which may consist of biomedical engineers, information technology experts, as well as clinicians, are required to solve complex issues regarding data capture, processing, storage, and interpretation, in order for such systems to be deemed clinically valuable. However, clinicians would gain a thorough understanding of the impact of patient management on their patients’ lives, particularly in relation to whether clinical management has changed the way in which daily activities are performed. The benefits of such systems are, therefore, potentially huge.

Wearable wrist activity monitor as an indicator of functional hand use in children with cerebral palsy

New tools that capture hand function in everyday activities and contexts are needed for assessing children with hemiplegic cerebral palsy. This study evaluates a wearable wrist monitor and tests the hypothesis that wrist extension frequency (FreqE) is an appropriate indicator of functional hand use. Fifteen children (four females, 11 males; age range 6-12y; mean age 10y [SD 2y]) with hemiplegia (seven at level I and eight at level II on the Manual Ability Classification System) participated in the Assisting Hand Assessment (AHA) while wearing the wrist monitor. FreqEs were captured via the wrist monitor and validated using video analysis. Correlations between FreqE and AHA scores were calculated and a multivariate linear regression was conducted to explore other measures of wrist activity. Wrist extensions observed in video analyses were reliably detected by the wrist monitor (intraclass correlation coefficient, r=0.88; p<0.001) and were strongly correlated with the AHA scores (r=0.93; p<0.001). AHA scores were significantly correlated with FreqE (r=0.80; p=0.001) and the range of wrist extensions/flexions (r=0.70; p=0.008). The multivariate linear regression combining the FreqE and range of wrist extensions/flexions yielded a strong correlation with AHA scores (r=0.84; p=0.0043). The wearable wrist monitor may offer a convenient, valid alternative to observer reports for functional assessments of the hemiplegic hand in everyday contexts.

How well do truck drivers sleep in cabin sleeper berths?

The aim of this study was to evaluate the sleep obtained by livestock transport truck drivers while resting in truck sleeper berths during long-haul commercial operations. Operations were carried out in the very remote regions of Australia. The sample comprised of 32 drivers who wore wrist activity monitors and reported bed-times for a two-week period. Drivers had a mean (±standard deviation) age of 35.41 (±9.78) years and had worked as truck drivers for 13.83 (±9.11) years. On average, they obtained 6.07 (±1.18) hours of sleep/24-h period. The majority of sleep occurred at night, but drivers occasionally supplemented their main sleep with a daytime nap. Consistent with operational demands, drivers were most likely to sleep in cabin sleeper berths ( n = 394, 77%). Only a small proportion of sleeps were sampled at home ( n = 63, 12%) or at truck depots ( n = 56, 11%). Mixed-model ANOVA revealed that while earlier bed-times at home yielded more sleep, there were only marginal differences in sleep quality across location. No intrinsic safety concerns associated with the use of sleeper berths were identified across consecutive days of long-haul transport operations.

Behavior modeling in industrial assembly lines using a wrist-worn inertial measurement unit

In this study an approach to an imperceptible and reliable worker monitoring system for industrial assembly lines is presented. A single wrist-worn inertial measurement unit is attached to the active wrist of the worker and by using acceleration and angular speed information, the behavior of the worker is recognized. The recognition is done in two steps. First the data are divided into 2-s intervals in which the performed activity is recognized using a knn classifier so that the system is usable online. In the second step, a state machine is used to recognize the completed tasks by searching for continuous, unvarying activity chains. The approach was developed as user-independent, although it can be easily adapted to a user-dependent case. By using the approach, behavior was recognized correctly and, on average, the correct beginning and ending moments of the behavior were missed by only 1 s. Thus a reliable monitoring system can be developed for industrial assembly lines. This work was supported by the EU 6th Framework Program Project XPRESS.

Prospective Study of Distal Radial Fractures Treated with an Intramedullary Nail

Intramedullary nailing for the treatment of unstable distal radial fractures is reported to provide stable fixation with minimal soft-tissue complications, but there is a paucity of data documenting the results of this technique. The purpose of this study was to prospectively determine the functional outcomes of treatment of unstable distal radial fractures with an intramedullary nail. Patients aged fifty years and older with a dorsally displaced unstable distal radial fracture--an extra-articular or simple intra-articular fracture--that was amenable to closed or percutaneous reduction were offered treatment with intramedullary nail fixation (MICRONAIL). Thirty-one patients were enrolled in the study, and twenty-nine patients with a mean age of sixty-seven years (range, fifty-one to eighty-five years) were available for one-year follow-up. According to the AO classification, there was one type-A2, twenty-four type-A3, and four type-C2 distal radial fractures. The patients were evaluated at six weeks, three months, six months, and one year after surgery. Outcome measures included standard radiographic parameters, active wrist range of motion, grip strength, a modified Mayo wrist score, and the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire. At the final one-year follow-up evaluation, the active range of motion of the injured wrist relative to that on the uninjured side averaged 95% of flexion, 95% of extension, 93% of ulnar deviation, 91% of radial deviation, 99% of pronation, and 99% of supination. The mean grip strength was 96% of that on the uninjured side. According to the modified Mayo wrist score, there were twenty excellent and nine good results. The mean DASH score was 4.8 points. The final radiographic measurements demonstrated, on average, 25° of radial inclination, 11° of volar tilt, 10 mm of radial length, and +1 mm of ulnar variance. Loss of reduction occurred in two patients. One patient developed transient superficial radial sensory neuritis, which resolved within two months. Intramedullary nailing can be a safe and effective treatment with minimal complications for dorsally displaced unstable extra-articular or simple intra-articular distal radial fractures.

Repair of Flexor Carpi Radialis Tendon Laceration at the Wrist in a Professional Ice Hockey Player

The flexor carpi radialis is a wrist flexor and radial deviator with half the relative strength of flexor carpi ulnaris. In the majority of patients, the flexor carpi radialis tendon is expendable and is routinely used for various reconstructive procedures about the hand and wrist. Isolated flexor carpi radialis lacerations at the wrist are rare. Flexor carpi radialis tendon ruptures, which have been reported in association with distal radius fractures, longstanding osteoarthritis, and percutaneous treatment of scaphoid fractures, are usually treated non-operatively. We report a case of a traumatic laceration of the flexor carpi radialis tendon at the wrist in a professional ice hockey player. Surgical repair and rehabilitation using established principles for intrasynovial flexor tendon repair allowed return to sport at the professional level in 2 months.Tension-free core suture repair was performed with a modified-Kessler, 4-strand repair using a double-stranded 4-0 Supramid suture. A running epitendinous suture was then placed around the circumference of the tendon with 6-0 Prolene. Immobilization of the wrist in 20° of flexion was maintained for 2 weeks. Full active and passive digital motion was allowed immediately postoperatively and continued throughout the rehabilitation. Therapy was initiated at 2 weeks postoperatively with full passive wrist flexion and passive wrist extension to a dorsal block of 20°. At 4 weeks postoperatively, a dorsal splint was fabricated to keep the wrist in neutral. At this time, active extension to a dorsal block of zero and full passive flexion was allowed. Active wrist flexion without resistance was begun at 6 weeks, and full strengthening was allowed at 8 weeks postoperatively. The patient returned to sport at the professional level shortly thereafter. At latest follow-up, the patient has been able to fully participate in professional ice hockey without pain or functional limitation.

Outcome After Tendon Transfers to Restore Wrist Extension in Children With Brachial Plexus Birth Injuries

Children with brachial plexus birth injuries often require tendon transfer to restore active wrist extension and maximize hand function. The purpose of this study is to assess the clinical results in children with brachial plexus birth injuries after tendon transfer to reconstruct active wrist extension. Over a 10-year period, 21 children (11 male, 10 female) underwent tendon transfer to reconstruct active wrist extension by a single surgeon. Eight patients had C5/C6/C7 injury and 13 patients had global palsy (C5-T1). The average age at surgery was 5.5 years (range, 3 to 8 y). Restoration of wrist extension was measured according to the functional scale of Duclos and Gilbert. The mean duration of follow-up was 36 months (minimum follow-up of 1 y). At latest follow-up, 14 (66%) children (C5/C6/C7, n=8; global, n=6) demonstrated active wrist extension ≥ 30 degrees. Within the global injury subcohort, 3 patients demonstrated static extension of the wrist. Four failures occurred in the global palsy group. Children with absent active wrist extension after a brachial plexus birth injury can benefit from a tendon transfer. The more severe global palsy cases have a worse outcome.

Mediokarpale Teilarthrodese des Handgelenks mittels Spiderplatte

Pain relief while preserving wrist motion in advanced carpal collapse. Advanced carpal collapse stage II/III due to scaphoid non-union, scapholunate ligament tear, idiopathic radiocarpal osteoarthritis, aseptic osteonecrosis of the scaphoid (Preisser's disease). A relative indication is chronic midcarpal instability. Osteoarthrisis of the lunate. Radiocarpal instability with ulnar translation of the wrist. Dorsal curved incision between the 3rd and 4th dorsal extensor compartment. Partial wrist denervation (posterior interosseous nerve). Raising of a radial pedicled capsule flap. Complete extirpation of the scaphoid without fragmentation. Cartilage removal of all the joint facets for arthrodesis. Reduction of the lunate and temporary fixation with K wires between the triquetrum and capitate and the triquetrum and lunate. Milling the plate hole exactly in central position of the four carpal bones. The plate should not protrude from the bone to avoid impingement with the dorsal limb of the radius. Transferring of spongiosa harvested from the removed scaphoid into the arthrodesis gap. Fixation of the 8-hole plate with 2 screws in each of the four carpal bones. Fluoroscopy of the screw fitting. Control of the correct wrist articulation (motion test). Lavage of the wrist. Suture of the capsule flap. Redon drain, wound closure, dorsal splinting. Dorsal splint for 3 weeks; finger mobilization up to complete fist closure starting on postoperative day 1. From week 4-6, active wrist motion, from week 7-10 with increasing load. Return to work after 11-12 weeks. CT scan in cases of delayed union, abnormal function, or persistence of pain. Between 2002 and 2008, 36 four-corner fusions (32 male, 4 female) with the spider plate were performed in 24 right and 12 left wrists. The mean age of the patients at surgery was 48 years (range 32-71 years). Follow-up examinations were performed in 11 patients. The Krimmer and Rudolf scores were determined: 1 excellent, 7 good, 2 satisfactory, and 1 poor result were found. The mean grip strength was 51% relative to the opposite wrist. The mean range of motion (ROM) for wrist extension/flexion was 56% of the opposite side. Wrist extension/flexion averaged 24/0/32° and ulnar/radial deviation was on average 20/0/19°. Pain during activity was on average 2.2 based on the visual analogue scale (0-10). One delayed bony union due to a screw breakage, which required total wrist fusion, was observed.

Electroestimulación en el tratamiento de la mano hemipléjica espástica después de un ictus: estudio aleatorizado

Background and objective It has been claimed that neuromuscular electrical stimulation (NMES) may enhance hand motor recovery after a stroke. The aim of this study was to examine the effect of an electrostimulation protocol on range of motion and strength of the hand in a group of elderly patients with spastic hemiplegia after a stroke. Patients and method 20 elderly patients 60 years old and over with hand impairment due to stroke were randomly assigned to either the experimental group (conventional rehabilitation and NMES) or control group (conventional rehabilitation). NMES was applied on wrist and finger extensors 30 min 3 days/week for 8 weeks. Outcome measurements included goniometry and dynamometry tests. The patients were evaluated at baseline, after 4 and 8 weeks of treatment. Results After the treatment, the experimental group showed significant improvements (p < 0,05) in range of motion: resting wrist angle, active wrist extension, passive wrist extension and resting metacarpophalangeal angle of fingers; and strength of hand: grip and pinch strength. Conclusion The observed changes seem to be associated with the presence of intervention and they suggest that the NMES protocol applied could be a useful complementary rehabilitation treatment to improve hand motor impairment in carefully selected patients after a stroke.

Ligament reconstruction using the Fulkerson-Watson method to treat chronic isolated distal radioulnar joint instability: short-term results

Isolated distal radioulnar instability may remain unrecognized during the acute period of trauma as it is difficult to diagnose, and does not become obvious until later when it has become chronic. We present early results in patients who underwent stabilization with extraarticular ligament reconstruction (Fulkerson-Watson reconstruction). Four women and 1 man underwent surgery for chronic isolated distal radioulnar joint instability demonstrated in X-rays and magnetic resonance images. Arthroscopy revealed avulsion of the triangular fibrocartilage complex from the point of insertion in 3 patients, and peripheral tears in 2 patients. The peripheral tears were debrided arthroscopically. All patients had an adequate sigmoid notch and therefore underwent ligament reconstruction using the Fulkerson-Watson method. Postoperative evaluations were done with MRI. Mean follow-up was 15.5 months (range 6-26 months). Stability was achieved in all patients. The mean Quick-DASH symptom score decreased from 18.63 (15.90-22.72) to 6.81 (2.27-9.09) after surgery. A mean visual analogue score to assess pain decreased from 7.32 (6.30-8.40) to 1.88 (1.50-2.30) after surgery. Preoperative and postoperative measurements were 26° (passive 44°) and 47° (passive 65°) for active supination, 18° (passive 45°) and 49°(passive 68°) for active pronation, 20° (passive 43°) and 42° (passive 60°) for active wrist flexion,and 38° (passive 52°) and 45° (passive 59°) for active wrist extension. Surgical revision of distal radioulnar joint instability using Fulkerson-Watson reconstruction is easier than intraarticular techniques and satisfactorily re-establishes stability, provided that the sigmoid notch is adequate.

Longitudinal Study of Sleep Patterns of United States Military Academy Cadets

The study provided an opportunity to observe sleep patterns in a college-age population attending the United States Military Academy. This 4-year longitudinal study investigated sleep patterns of cadets. A stratified sample of 80 cadets had sleep patterns monitored using actigraphy for 8 months: one month in both fall and spring academic semesters over a 4-year period. Data were collected at the United States Military Academy, West Point, NY. Participants were members of the class of 2007 (n˜1300) ranging in age from 17 to 22 when entering USMA. A sample of the class (n=80) wore wrist activity monitors and completed activity logs for one month in fall and spring academic semesters for the 4-year period. On average over the 4 years, cadets slept<5.5 h on school nights. Cadets napped extensively, perhaps in an attempt to compensate for chronic sleep debt. Cadets slept more during fall than spring semesters. Male and female cadet sleep patterns varied dramatically, with males consistently receiving less sleep than females (˜21 m for nighttime sleep and ˜23 m for daily sleep). Cadet sleep at USMA is related to academic year, semester, season, sex, school day or weekend, and day of the week. These students suffer from chronic sleep debt. Restrictions imposed by the military academy limit the generalizability of the findings to other college age populations.

A New Integrated Variable Based on Thermometry, Actimetry and Body Position (TAP) to Evaluate Circadian System Status in Humans

The disruption of the circadian system in humans has been associated with the development of chronic illnesses and the worsening of pre-existing pathologies. Therefore, the assessment of human circadian system function under free living conditions using non-invasive techniques needs further research. Traditionally, overt rhythms such as activity and body temperature have been analyzed separately; however, a comprehensive index could reduce individual recording artifacts. Thus, a new variable (TAP), based on the integrated analysis of three simultaneous recordings: skin wrist temperature (T), motor activity (A) and body position (P) has been developed. Furthermore, we also tested the reliability of a single numerical index, the Circadian Function Index (CFI), to determine the circadian robustness. An actimeter and a temperature sensor were placed on the arm and wrist of the non-dominant hand, respectively, of 49 healthy young volunteers for a period of one week. T, A and P values were normalized for each subject. A non-parametric analysis was applied to both TAP and the separate variables to calculate their interdaily stability, intradaily variability and relative amplitude, and these values were then used for the CFI calculation. Modeling analyses were performed in order to determine TAP and CFI reliability. Each variable (T, A, P or TAP) was independently correlated with rest-activity logs kept by the volunteers. The highest correlation (r = −0.993, p<0.0001), along with highest specificity (0.870), sensitivity (0.740) and accuracy (0.904), were obtained when rest-activity records were compared to TAP. Furthermore, the CFI proved to be very sensitive to changes in circadian robustness. Our results demonstrate that the integrated TAP variable and the CFI calculation are powerful methods to assess circadian system status, improving sensitivity, specificity and accuracy in differentiating activity from rest over the analysis of wrist temperature, body position or activity alone.

PHASE RELATIONSHIP BETWEEN SKIN TEMPERATURE AND SLEEP-WAKE RHYTHMS IN WOMEN WITH VASCULAR DYSREGULATION AND CONTROLS UNDER REAL-LIFE CONDITIONS

The aim of the study was to investigate whether women with primary vascular dysregulation (VD; main symptoms of thermal discomfort with cold extremities) and difficulties initiating sleep (DIS) exhibit a disturbed phase of entrainment (Ψ) under everyday life conditions. The authors predicted a phase delay of the distal-proximal skin temperature gradient and salivary melatonin rhythms with respect to the sleep-wake cycle in women with VD and DIS (WVD) compared to controls (CON), similar to that found in their previous constant-routine laboratory data. A total of 41 young healthy women, 20 with WVD and 21 matched CON without VD and normal sleep onset latency (SOL), were investigated under ambulatory conditions (following their habitual bedtimes) during 7 days of continuous recording of skin temperatures, sleep-wake cycles monitored by actimetry and sleep-wake diaries, and single evening saliva collections for determining the circadian marker of dim light melatonin onset (DLMO). Compared to CON, WVD showed increased distal vasoconstriction at midday and in the evening, as indicated by lower distal (DIST; hands and feet) and foot-calf skin temperatures, and distal-proximal skin temperature gradients (p < .05). WVD manifested distal vasoconstriction before lights-off that also lasted longer after lights-off than in CON. In parallel, WVD exhibited a longer SOL (p < .05). To define internal phase-relationships, cross-correlation analyses were performed using diurnal rhythms of wrist activity and foot skin temperature. WVD showed a phase delay in foot skin temperature (CON versus WVD: 3.57 ± 17.28 min versus 38.50 ± 16.65 min; p < .05) but not in wrist activity. This finding was validated by additional within-subject cross-correlation analyses using the diurnal wrist activity pattern as reference. DLMO and habitual sleep times did not differ between CON and WVD. The authors conclude that WVD exhibit a phase delay of distal vasodilatation with respect to their habitual sleep-wake cycle and other circadian phase markers, such as DLMO. A full factorial design will have to show whether the finding is specific to primary vascular dysregualtion, to DIS, or to their interaction. (Author correspondence: Kurt.kraeuchi@upkbs.ch)