Cerebellar dysmetria at the elbow, wrist, and fingers

1. The objective was to investigate in cerebellar patients with dysmetria the kinematic and electromyographic (EMG) characteristics of large and small movements at the elbow, wrist, and finger and thereby to determine the nature of cerebellar dysmetria at distal as well as proximal joints. Flexions were made as fast as possible by moving relatively heavy manipulanda for each joint to the same end position through 5, 30, and 60 degrees. 2. In normal subjects flexions at all joints were accompanied by similar triphasic EMG activity. Movements of increasing amplitude were made with increasing movement durations and increasing durations and magnitudes of initial agonist EMG activity. Antagonist activity often appeared to have two components: one coactive with the initial agonist burst but starting later, the other reaching its peak at about peak velocity. 3. Cerebellar patients with dysmetria showed hypermetria followed by tremor at all three joints when movements were made with the manipulanda. Hypermetria was most marked for aimed movements of small amplitude (5 degrees) at all joints. 4. A characteristic of cerebellar disordered movements, which could be present at all amplitudes and all joints, was an asymmetry with decreased peak accelerations and increased peak decelerations compared to normal movements. Both the asymmetry and the hypermetria for small amplitude movements could be used clinically as sensitive indicators of cerebellar dysfunction. 5. The EMG abnormalities accompanying hypermetria and asymmetry were a more gradual buildup and a prolongation of agonist activity and delayed onset of antagonist activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Using motor imagery in the rehabilitation of hemiparesis

OBJECTIVE

To examine the effectiveness of using motor imagery training in the rehabilitation of hemiparesis.

DESIGN

A before-after trial with clinical and behavioral analyses of single cases.

SETTING

Academic-affiliated rehabilitation hospital.

PARTICIPANTS

Two survivors of embolic middle cerebral artery stroke that resulted in chronic hemiparesis.

INTERVENTION

A motor imagery training program consisting of imagined wrist movements (extension, pronation-supination) and mental simulations of reaching and object manipulation making use of a mirror box apparatus. Twelve 1-hour experimental sessions were delivered, 3 times a week for 4 consecutive weeks.

MAIN OUTCOME MEASURES

Two clinical assessments, grip strength, 4 wrist functionality measurements, and 3 timed performance tests. All outcome measures were recorded before training began, at 3 times during the intervention month, with 2 additional long-term measurements.

RESULTS

Performance of the paretic limb improved after the imagery intervention, indicated by increases in assessment scores and functionality and decreases in movement times. The improvements over baseline performance remained stable over a 3-month period.

CONCLUSIONS

These results demonstrate the potential for using motor imagery as a cognitive strategy for functional recovery from hemiparesis. The intervention targets the cognitive level of action processing while its effects may be realized in overt behavioral performance.

Chronic motor dysfunction after stroke: recovering wrist and finger extension by electromyography-triggered neuromuscular stimulation

BACKGROUND AND PURPOSE

After stroke, many individuals have chronic unilateral motor dysfunction in the upper extremity that severely limits their functional movement control. The purpose of this study was to determine the effect of electromyography-triggered neuromuscular electrical stimulation on the wrist and finger extension muscles in individuals who had a stroke > or = 1 year earlier.

METHODS

Eleven individuals volunteered to participate and were randomly assigned to either the electromyography-triggered neuromuscular stimulation experimental group (7 subjects) or the control group (4 subjects). After completing a pretest involving 5 motor capability tests, the poststroke subjects completed 12 treatment sessions (30 minutes each) according to group assignments. Once the control subjects completed 12 sessions attempting wrist and finger extension without any external assistance and were posttested, they were then given 12 sessions of the rehabilitation treatment.

RESULTS

The Box and Block test and the force-generation task (sustained muscular contraction) revealed significant findings (P<0. 05). The experimental group moved significantly more blocks and displayed a higher isometric force impulse after the rehabilitation treatment.

CONCLUSIONS

Two lines of evidence clearly support the use of the electromyography-triggered neuromuscular electrical stimulation treatment to rehabilitate wrist and finger extension movements of hemiparetic individuals > or =1 year after stroke. The treatment program decreased motor dysfunction and improved the motor capabilities in this group of poststroke individuals.

Outcome evaluation measures for wrist and hand: which one to choose?

The aim of this study was to critically analyse the various outcome measures available for assessing wrist and hand function. To this end, an extensive literature search was performed on Medline, PubMed and the Science Citation Index, focusing on terms associated with the method of development of the outcome measures item generation, item reduction, validity, reliability, internal consistency and their strengths and weaknesses. The most commonly used outcome measures described in literature were the DASH score (disability of shoulder, arm and hand questionnaire), the PRWE score (patient-rated wrist evaluation questionnaire), the Brigham and Women's carpal tunnel questionnaire and the Gartland and Werley score. Our study provides very useful evidence to suggest that the PRWE score is the most responsive instrument for evaluating the outcome in patients with distal radius fractures, while the DASH score is the best instrument for evaluating patients with disorders involving multiple joints of the upper limb. The Brigham and Women's score is a disease-specific outcome instrument for carpal tunnel syndrome; it has been validated and demonstrated to show good responsiveness and reliability in evaluating outcome in patients with carpal tunnel release. The Gartland and Werley score, although the most commonly described instrument in the literature for evaluating outcome after wrist surgery, has not been validated so to date.

Computerized Arm Training Improves the Motor Control of the Severely Affected Arm After Stroke

Background and Purpose— To compare a computerized arm trainer (AT), allowing repetitive practice of passive and active bilateral forearm and wrist movement cycle, and electromyography-initiated electrical stimulation (ES) of the paretic wrist extensor in severely affected subacute stroke patients.

Method— A total of 44 patients, 4 to 8 weeks after stroke causing severe arm paresis (Fugl–Meyer Motor Score [FM, 0 to 66] <18), were randomly assigned to either AT or ES. All patients practiced 20 minutes every workday for 6 weeks. AT patients performed 800 repetitions per session with the robot and ES patients performed 60 to 80 wrist extensions per session. The primary outcome measure was the blindly assessed FM (0 to 66), and the secondary measures were the upper limb muscle power (Medical Research Council [MRC] sum, 0 to 45) and muscle tone (Ashworth score sum, 0 to 25), assessed at the beginning and end of treatment and at 3-month follow-up.

Results— The AT group had a higher Barthel Index score at baseline, but the groups were otherwise homogenous. As expected, FM and MRC sum scores improved overtime in both groups but significantly more in the robot AT group. The initial Barthel Index score had no influence. In the robot AT group, FM score was 15 points higher at study end and 13 points higher at 3-month follow-up than the control ES group. MRC sum score was 15 points higher at study end and at 3-month follow-up compared with the control ES group. Muscle tone remained unchanged, and no side effects occurred.

Conclusion— The computerized active arm training produced a superior improvement in upper limb motor control and power compared with ES in severely affected stroke patients. This is probably attributable to the greater number of repetitions and the bilateral approach.

A biomechanical study of distal radial fractures

In an attempt to explain disability in dorsally angulated malunited distal radius fractures, an experiment was designed to evaluate load patterns about the wrist with varying degrees of dorsal angulation of the distal radius. Osteotomies were made in the distal radius of fresh cadaver arms after a modified external fixator was applied to the radius and load cells applied to the proximal radius and ulna. Pressure-sensitive film was inserted into the radioulnar carpal joint. After a predetermined load was applied to the wrist it was found that the load through the ulna increased from 21% to 67% of the total load as the angulation of the distal radial fragment increased from 10 degrees of palmar tilt to 45 degrees of dorsal tilt. The pressure distribution on the ulnar and radial articular surfaces changed in position and became more concentrated as dorsal angulation increased.

Presynaptic inhibition and homosynaptic depression: a comparison between lower and upper limbs in normal human subjects and patients with hemiplegia

Presynaptic inhibition of Ia terminals and postactivation depression at the Ia fibre-motor neuron (MN) synapses were compared in the upper and lower limbs of both sides in subjects from different populations: 49 spastic patients with hemiplegia [mainly with a lesion in the middle cerebral artery (MCA) area], two tetraplegics and 35 healthy subjects. Presynaptic inhibition was assessed using D1 inhibition of the soleus and the flexor carpi radialis (FCR) H reflexes elicited by electrical stimuli applied to the nerve supplying antagonistic muscles, and postactivation depression was explored by varying the time interval between two consecutive H reflexes. In normal subjects no right-left asymmetry was found in the amount of presynaptic Ia inhibition, homosynaptic depression or the H(max)/M(max) ratio. In the hemiplegic side of patients with MCA area lesions, the H(max)/M(max) ratio was significantly increased in the soleus but not in the FCR. Presynaptic inhibition of Ia terminals, which was significantly reduced at the cervical level on the hemiplegic side (and also, but to a lesser extent, on the unaffected side), was unchanged at the lumbar level. Homosynaptic depression was similarly reduced at the cervical and lumbar levels on the hemiplegic side but not modified on the unaffected side. It is argued that the decrease in presynaptic inhibition of Ia terminals is more a correlate of spasticity than a mechanism underlying it. The decrease in postactivation depression, which very probably contributes to the exaggeration of the stretch reflex characterizing spasticity, might be a consequence of the changes in the pattern of activation of Ia afferents and MNs following the motor impairment.

Impaired limb position sense after stroke: a quantitative test for clinical use

OBJECTIVE

A quantitative measure of wrist position sense was developed to advance clinical measurement of proprioceptive limb sensibility after stroke. Test-retest reliability, normative standards, and ability to discriminate impaired and unimpaired performance were investigated.

DESIGN

Retest reliability was assessed over three sessions, and a matched-pairs study compared stroke and unimpaired subjects. Both wrists were tested, in counterbalanced order.

SETTING

Patients were tested in hospital-based rehabilitation units.

PATIENTS AND OTHER PARTICIPANTS

Reliability was investigated on a consecutive sample of 35 adult stroke patients with a range of proprioceptive discrimination abilities and no evidence of neglect. A consecutive sample of 50 stroke patients and convenience sample of 50 healthy volunteers, matched for age, sex, and hand dominance, were tested in the normative-discriminative study. Age and sex were representative of the adult stroke population.

MAIN OUTCOME MEASURES

The test required matching of imposed wrist positions using a pointer aligned with the axis of movement and a protractor scale.

RESULTS

The test was reliable (r = .88 and .92) and observed changes of 8 degrees can be interpreted, with 95% confidence, as genuine. Scores of healthy volunteers ranged from 3.1 degrees to 10.9 degrees average error. The criterion of impairment was conservatively defined as 11 degrees (+/-4.8 degrees) average error. Impaired and unimpaired performance were well differentiated.

CONCLUSIONS

Clinicians can confidently and quantitatively sample one aspect of proprioceptive sensibility in stroke patients using the wrist position sense test. Development of tests on other joints using the present approach is supported by our findings.

Prediction of wrist arteriovenous fistula maturation with preoperative vein mapping with ultrasonography

OBJECTIVE

The purpose of this study was to determine whether the preoperative minimal cephalic vein size in the forearm was predictive of successful wrist fistula maturation to a functional hemodialysis access.

METHODS

Forty-four consecutive patients underwent evaluation before surgery with ultrasound scan imaging to map the entire cephalic vein in preparation for the construction of an arteriovenous fistula at the wrist. Measurements of the vein diameter were obtained from the ultrasound scan images at eight representative sites. Patients were clinically followed to determine maturation of the fistula to provide a functional hemodialysis access. The smallest diameter of the cephalic vein then was used as a preoperative predictor of fistula maturation.

RESULTS

Successful maturation of the arteriovenous fistula was achieved in 22 of the procedures (50%). Cephalic veins with a minimal diameter of 2.0 mm or less were used for anastamosis in 19 patients (43%), and three of these procedures (16%) led to a functional access site. The remaining 25 patients (57%) had minimal cephalic vein diameters greater than 2.0 mm, producing a successful maturation in 19 of the fistula creations (76%). A significantly higher rate of successful fistula maturation in those patients with a preoperative minimal cephalic vein size greater than 2.0 mm was realized (P =.0002, chi(2) test, with Yates correction for continuity).

CONCLUSION

In patients with a minimal cephalic vein size of 2.0 mm or less, a procedure other than wrist fistula should be considered for optimization of dialysis access.

Axonal excitability properties in amyotrophic lateral sclerosis

OBJECTIVE

To investigate axolemmal ion channel function in patients diagnosed with sporadic amyotrophic lateral sclerosis (ALS).

METHODS

A recently described threshold tracking protocol was implemented to measure multiple indices of axonal excitability in 26 ALS patients by stimulating the median motor nerve at the wrist. The excitability indices studied included: stimulus-response curve (SR); strength-duration time constant (tauSD); current/threshold relationship; threshold electrotonus to a 100 ms polarizing current; and recovery curves to a supramaximal stimulus.

RESULTS

Compound muscle action potential (CMAP) amplitudes were significantly reduced in ALS patients (ALS, 2.84+/-1.17 mV; controls, 8.27+/-1.09 mV, P<0.0005) and the SR curves for both 0.2 and 1 ms pulse widths were shifted in a hyperpolarized direction. Threshold electrotonus revealed a greater threshold change to both depolarizing and hyperpolarizing conditioning stimuli, similar to the 'fanned out' appearance that occurs with membrane hyperpolarization. The tauSD was significantly increased in ALS patients (ALS, 0.50+/-0.03 ms; controls, 0.42+/-0.02 ms, P<0.05). The recovery cycle of excitability following a conditioning supramaximal stimulus revealed increased superexcitability in ALS patients (ALS, 29.63+/-1.25%; controls, 25.11+/-1.01%, P<0.01).

CONCLUSIONS

Threshold tracking studies revealed changes indicative of widespread dysfunction in axonal ion channel conduction, including increased persistent Na+ channel conduction, and abnormalities of fast paranodal K+ and internodal slow K+ channel function, in ALS patients.

SIGNIFICANCE

An increase in persistent Na+ conductances coupled with reduction in K+ currents would predispose axons of ALS patients to generation of fasciculations and cramps. Axonal excitability studies may provide insight into mechanisms responsible for motor neuron loss in ALS.

Tremor, the cogwheel phenomenon and clonus in Parkinson's disease

Resting and postural tremor, intention and action tremor, clonus and the cogwheel phenomenon in Parkinson's disease have been characterised in terms of frequency content using spectral analysis. Typical resting tremor ranged in peak frequency from 4 to 5.3 HZ with tremor in each individual varying only by 0.2 to 0.3 HZ. The peak frequency of postural tremor ranged between 6 and 6.2 HZ. Intention tremor appeared to be an exaggeration of postural tremor. Clonus evoked by active or passive stretch at the wrist had a frequency of 6 HZ and appeared to be a continuation of postural tremor. The cogwheel phenomenon was found at frequencies between 6 and 6.5 HZ and between 7.5 to 9 HZ. Action tremor was indistinguishable from the cogwheel phenomenon. Some patients had either a symptomatic resting tremor with a concurrent 6 HZ component of smaller amplitude or a symptomatic postural tremor with a 4-5 HZ component of smaller amplitude. These combinations would produce two peaks in the power spectrum. When this occurred EMG studies showed that individual muscles had two types of rhythmical activation suggesting that the tremors have separate mechanisms. Likewise some patients had a symptomatic 6 HZ tremor on posture with a second peak at 8-10 HZ in the physiological band. Therefore, the 6 HZ postural tremor is not an exaggeration of physiological tremor. On the basis of wave form and frequency similarities postural tremor, the low frequency type of active or passive cogwheeling, intention tremor and clonus possibly involve a common spinal mechanism. Higher frequency cogwheel phenomenon and action tremor may be an exaggeration of physiological tremor. More than 80% of patients with Parkinson's disease manifest tremors at both 4-5 HZ and 6 HZ. This combination would appear to be the strongest objective criterion for the diagnosis of basal ganglia disease.

Impaired inhibition in writer's cramp during voluntary muscle activation

We used paired transcranial magnetic stimulation (TMS) to evaluate inhibitory mechanisms in eight patients with writer's cramp during rest and isometric wrist extension. Both stimuli were 110% of the motor threshold; the interstimulus intervals (ISIs) were 20 to 200 ms in increments of 10 ms. Surface EMG was recorded from wrist extensors. In the symptomatic hemisphere, there was no significant difference in the amplitude of the test (second) motor evoked-potential (MEP) between patients and age-matched controls at rest. However, with voluntary muscle activation, inhibition of the test MEP by the conditioning MEP was significantly less in writer's cramp patients than in controls (p = 0.02). The difference was most prominent at ISIs of 60 to 80 ms in which inhibition is maximum. In the asymptomatic hemisphere, there was no significant difference between patients and controls in both rest and active conditions. The silent period was shorter in patients than controls on the symptomatic side (p = 0.003) but not on the asymptomatic side. We conclude that the inhibitory effects induced by magnetic stimulation are reduced in patients with writer's cramp, but only on the symptomatic side during muscle activation. This may relate to the overflow of muscle activity that characterizes this condition.

Dose-dependent response to intramuscular botulinum toxin type A for upper-limb spasticity in patients after a stroke

OBJECTIVE

To test the hypothesis that intramuscular (IM) botulinum toxin type A (BTX) reduces excessive muscle tone in a dose-dependent manner in the elbow, wrist, and fingers of patients who experience spasticity after a stroke.

DESIGN

Randomized, double-blind, placebo-controlled, multicenter, 24-week trial.

SETTING

Six academic and 13 private US outpatient medical centers.

PARTICIPANTS

Ninety-one patients with a mean age of 60 years (range, 30-79 y). Mean time elapsed from ischemic or hemorrhagic stroke to study enrollment was 25.8 months (range, 0.9-226.9 mo).

INTERVENTIONS

Up to 2 treatments of placebo, or 90, 180, or 360U of BTX. Concurrent splinting and physical therapy protocols were permitted, but no changes were allowed during the study.

MAIN OUTCOME MEASURES

Wrist, elbow, and finger flexor tone assessed by the Modified Ashworth Scale, physician and patient global assessments, pain, FIM instrument, and Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36).

RESULTS

Muscle tone decreased more with injections of BTX than with placebo in the wrist flexors at weeks 1, 2, 3, 6, and 9 (P< or =.026); in the elbow flexors at weeks 1, 2, 3, 4, 5, and 9 (P< or =.033); and in the finger flexors at weeks 1 and 3 (P< or =.031). A dose-dependent response was generally observed in tone reduction but not in pain, FIM, or SF-36 measures.

CONCLUSIONS

IM BTX reduced muscle tone in a dose-dependent manner in the elbow, wrist, and fingers of patients who experience spasticity after a stroke but did not appear to affect global quality of life or disability.

Preliminary report: activation of the cerebellum in essential tremor

Several images of cerebral blood flow were recorded during inhalation of carbon-15-labelled carbon dioxide by positron emission tomography in four patients with essential tremor and four normal controls. Unilateral involuntary postural tremor in essential tremor patients was associated with blood flow significantly greater than that at rest in the contralateral sensorimotor cortex, both lateral premotor regions, and both cerebellar hemispheres. Of these regions, only the cerebellum was not activated in normal controls holding a posture without tremor or in essential tremor patients undergoing passive wrist movement. The increased flow in the cerebellum therefore seems to represent neural activity involved in tremor generation. It is proposed that essential tremor is due to oscillation within cerebello-olivary pathways, relayed by way of the thalamus and motor cortex to the spinal cord.

Sensory conduction from digit to palm and from palm to wrist in the carpal tunnel syndrome

In normal subjects the maximum and minimum conduction velocity along sensory nerve was the same from digit to palm and from palm to wrist. Severe slowing from palm to wrist in patients with the carpal tunnel syndrome was often associated with only slight slowing from digit to palm. The distal slowing is attributed to a reversible constriction of nerve fibres, an assumption supported by the recovery in distal conduction velocity as early as two and a half months after decompression. The sensory velocity from wrist to elbow was normal or supernormal, whereas the motor velocity was often slightly decreased. The exclusion of the normal segment of the median nerve distal to the flexor retinaculum made it possible to demonstrate abnormalities across the flexor retinaculum in patients with clinical signs of carpal tunnel syndrome in whom distal motor latency and sensory conduction from digit to wrist were normal.

Spasticity causes a fundamental rearrangement of muscle-joint interaction

Sarcomere length was measured in flexor carpi ulnaris (FCU) muscles from patients with severely spastic wrist flexion contractures (n = 6), as well as from patients with radial nerve injury and a normally innervated FCU (n = 12). Spastic FCU muscles had extremely long sarcomere lengths with the wrist fully flexed (3.48 +/- 0.44 microm) compared to the FCU muscles of patients with radial nerve injury (2.41 +/- 0.31 microm). In three of the patients with spastic wrist flexion contractures, the slope of the FCU sarcomere length-joint angle relationship was measured and found to be, essentially, normal (0.017 +/- 0.005 microm/degree, n = 3) suggesting that serial sarcomere number (and therefore muscle fiber length) was unchanged in spite of the dramatic absolute sarcomere length change. These results indicate that spasticity results in a major alteration of normal muscle-joint anatomical relationships that has not previously been recognized to our knowledge. We hypothesize that the results are explained either by the inability of muscle fibers to add serial sarcomeres in response to growth, or the selective loss of FCU muscle length secondary to the central nervous system lesion.

A positron emission tomography study of cerebral activation associated with essential and writing tremor

OBJECTIVE

To compare the abnormal patterns of cerebral activation associated with essential and writing tremors.

DESIGN

Positron emission tomography using oxygen 15-labeled water was utilized to determine regional cerebral blood flow. Positron emission tomography images that were taken of the brain in individual patients were coregistered with magnetic resonance images of the same brain to ascertain accurate localization of cerebral activation in single patients. Patients with essential tremor underwent scanning at rest, during involuntary postural tremor, and during passive wrist oscillation. Normal control subjects underwent scanning at rest and during voluntary and passive wrist oscillation. Patients with writing tremor underwent scanning while they were holding a pen to paper with consequent involuntary tremor and again while they were holding a pen in the same supinated arm without tremor.

SETTING

Research hospital.

PATIENTS OR OTHER PARTICIPANTS

Seven patients with essential tremor, six patients with writing tremor, and six matched control subjects.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Regional cerebral blood flow.

RESULTS

Essential tremor was associated with abnormal bilateral cerebellar, red nuclear, and thalamic activation. Writing tremor was also associated with abnormal bilateral cerebellar activation. Voluntary wrist oscillation in control subjects caused only ipsilateral cerebellar activation. These findings were evident in single patients, when positron emission tomography images were coregistered with magnetic resonance images and on group analysis of the pooled positron emission tomography data after transformation into stereotaxic space.

CONCLUSION

These results indicate that both essential and writing tremors are associated with abnormal bilateral overactivity of cerebellar connections.

Ulnar nerve excursion and strain at the elbow and wrist associated with upper extremity motion

Significant excursion of the ulnar nerve is required for unimpeded upper extremity motion. This study evaluated the excursion necessary to accommodate common motions of daily living and associated strain on the ulnar nerve. The 2 most common sites of nerve entrapment, the cubital tunnel and the entrance of Guyon's canal, were studied. Five fresh-frozen, thawed transthoracic cadaver specimens (10 arms) were dissected and the nerve was exposed at the elbow and wrist only enough to be marked with a microsuture. Excursion was measured with a laser mounted on a Vernier caliper fixed to the bone and aligned in the direction of nerve motion. A Microstrain (Burlington, VT) DVRT strain device was applied to the nerve at both the elbow and wrist. Nerve excursion associated with motion of the shoulder, elbow, wrist, and fingers (measured by goniometer) was measured at the wrist and elbow. An average of 4.9 mm ulnar nerve excursion was required at the elbow to accommodate shoulder motion from 30 degrees to 110 degrees of abduction, and 5.1 mm was needed for elbow motion from 10 degrees to 90 degrees. When the wrist was moved from 60 degrees of extension to 65 degrees of flexion, 13.6 mm excursion of the ulnar nerve was required at the wrist. When all the motions of the wrist, fingers, elbow, and shoulder were combined, 21.9 mm of ulnar nerve excursion was required at the elbow and 23.2 mm at the wrist. Ulnar nerve strain of 15% or greater was experienced at the elbow with elbow flexion and at the wrist with wrist extension and radial deviation. Any factor that limits excursion at these sites could result in repetitive traction of the nerve and possibly play a role in the pathophysiology of cubital tunnel syndrome or ulnar neuropathy at Guyon's canal.

Mal-union and dysfunction in Colles' fracture

Wrist function was assessed between one and three years after injury in patients who had suffered Colles' fractures. Both the range of wrist flexion and the strength of grip were found to be deficient. The loss of power in gripping was found to correlate with mal-union affecting the coronal and sagittal inclination of the articular surface of the radius.

Position of the wrist associated with the lowest carpal-tunnel pressure: implications for splint design

Increased carpal-tunnel pressure has been implicated in the pathophysiology of carpal tunnel syndrome, but it is not known whether splints that immobilize the wrist in a functional position of extension minimize carpal tunnel pressure. To determine the position of the wrist that results in the lowest carpal-tunnel pressure, twenty control subjects and four patients who had carpal tunnel syndrome were evaluated with use of a new, dynamic method that continuously measures carpal tunnel pressure throughout the range of motion of the wrist. The pressure was measured by means of a pressure transducer connected to a flexible catheter that had been inserted into the carpal canal. The position of the wrist was measured simultaneously with use of a two-axis electrogoniometer. Aided by a computer monitor that displayed a moving line of real-time carpal-tunnel pressure, each subject was instructed to move the wrist throughout the range of motion and to adjust it to the position that corresponded to the lowest carpal-tunnel pressure. For the control subjects, the lowest carpal-tunnel pressure averaged 8 +/- 4 millimeters of mercury (1.07 +/- 0.53 kilopascals), and the average position of the wrist associated with the lowest pressure was 2 +/- 9 degrees of extension and 2 +/- 6 degrees of ulnar deviation.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential effects of changes in mechanical limb properties on physiological and pathological tremor

The effect of changes in mechanical limb properties on the peak frequency of different tremor forms was analysed. Wrist tremor was recorded by an accelerometer fixed to the dorsum of the hand and demodulated surface EMG was recorded from the wrist extensors, while the extended hand was loaded with successively heavier weights. Physiological tremor was characterised by flat EMG spectra and a gradual decrease in tremor peak frequency with increasing load, as would be expected from the properties of a passive spring-mass-system. Also the peak frequency of activated physiological tremor characterised by increased synchronisation between motor units decreased in frequency with increasing loads. EMG spectra showed clear peaks of activity at the various mechanically determined tremor frequencies. In contrast, in two pathological tremor forms, the postural tremor in Parkinsonian patients and essential tremor, peak frequency tended to remain stable irrespective of changes in load. The method therefore allows a simple distinction between physiological and these two pathological tremors.

Influence of somatosensory input on motor function in patients with chronic stroke

In healthy volunteers, reduction of somatosensory input from one hand leads to rapid performance improvements in the other hand. Thus, it is possible that reduction of somatosensory input from the healthy hand can influence motor function in the paretic hand of chronic stroke patients with unilateral hand weakness. To test this hypothesis, we had 13 chronic stroke patients perform motor tasks with the paretic hand and arm during cutaneous anesthesia of the healthy hand and healthy foot in separate sessions. Performance of a finger tapping task, but not a wrist flexion task, improved significantly with anesthesia of the hand, but not the foot. This effect progressed with the duration of anesthesia and correlated with baseline motor function. We conclude that cutaneous anesthesia of the healthy hand elicits transient site-specific improvements in motor performance of the moderately paretic hand in patients with chronic stroke, consistent with interhemispheric competition models of sensorimotor processing.

Intracarpal steroid injection is safe and effective for short-term management of carpal tunnel syndrome

A double-blinded placebo-controlled trial was performed to evaluate the use of steroid injections beneath the transverse carpal ligament in the treatment of carpal tunnel syndrome (CTS) refractory to nonsurgical therapy. Forty-three patients received 6 mg betamethasone and lidocaine and 38 patients received 1 ml saline placebo and lidocaine. The primary outcome measure was satisfaction with symptom relief. Thirty patients (70%) in the steroid-treated group were satisfied or highly satisfied compared with 13 (34%) of placebo-treated patients (P < 0.001). Patients receiving steroids also showed significant improvement in median nerve conduction parameters and scores on validated symptom/function questionnaires. Forty-six patients were treated with serial injections for recurrent CTS symptoms. After 18 months, 17 patients reported adequate symptom relief with steroid injection, and 18 patients with unsatisfactory symptom relief were referred for carpal tunnel release surgery. We conclude that although steroid injections are safe and effective for temporary relief of CTS, most patients will eventually require surgery for long-term control of their symptoms.