Dynamic and static components of mechanical hyperalgesia in human hairy skin

The principle finding of the present study is that there are two types of mechanical hyperalgesia developing in human hairy skin following injurious stimuli. Mechanical hyperalgesia comprises a dynamic component (brush-evoked pain, allodynia) signalled by large myelinated afferents and a static component (hyperalgesia to pressure stimuli) signalled by unmyelinated afferents. While the static component is only found in the injured area, the dynamic component also extends into a halo of undamaged tissue surrounding the injury. The irritant chemicals, mustard oil or capsaicin, were applied transdermally in 20 subjects to a patch (2 x 2 cm) of hairy skin. Both substances evoked burning pain and hyperalgesia to mechanical stimuli. While stroking normal skin with a cotton bud was perceived only as touch prior to chemical stimulation, there was a distinctly unpleasant sensation afterwards. This component of mechanical hyperalgesia persisted for at least 30 min and was present in the skin exposed to the irritants (primary hyperalgesia) as well as in a zone of untreated skin surrounding the injury (secondary hyperalgesia) measuring 38 +/- 4 cm2 after capsaicin. Pressure pain thresholds dropped to 55 +/- 8% of baseline level after mustard oil and to 46 +/- 9% after capsaicin. However, this drop of thresholds was short-lived, lasting 5 min following mustard oil but persisting more than 30 min following capsaicin treatment. The reduction of pressure pain thresholds was only observed for treated skin areas, but not in the surrounding undamaged tissue from where brush-evoked pain could be evoked. When pressure pain thresholds were lowered, the pain had a burning quality which differed distinctly from the quality of brush-evoked pain. On-going burning pain and both types of mechanical hyperalgesia were critically temperature dependent. Mildly cooling the skin provided instant relief from on-going pain, abolished brush-evoked pain and normalized pressure pain thresholds. Rewarming resulted in a reappearance of on-going pain and hyperalgesia. The effect of a nerve compression block of the superficial radial nerve on these sensations was tested in 14 experiments. When the ability to perceive light touch had been abolished, there was also no touch-evoked pain, indicating that this component of mechanical hyperalgesia is mediated by large-diameter primary afferents. At a later stage of the block when the subjects' ability to perceive cold stimuli had also been lost, application of cool stimuli still eliminated on-going burning pain, suggesting that pain relief afforded by cooling the skin acts at the peripheral receptor level and not by central masking.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Ultrasonography shows extensive nerve enlargements in multifocal motor neuropathy

Using ultrasonography we found multiple sites with nerve enlargement along the course of the brachial plexus, median, ulnar, and radial nerves in the majority of 21 patients with multifocal motor neuropathy. Sonography and electrophysiologic studies showed more abnormalities than expected on purely clinical grounds. Moreover, sonography revealed nerve enlargement without clinical or electrophysiologic abnormalities.

Tennis elbow. Anatomical, epidemiological and therapeutic aspects

Five studies of tennis elbow are presented. Epidemiological studies showed an incidence of tennis elbow between 1 and 2%. The prevalence of tennis elbow in women between 40 and 50 years of age was 10%. Half of the patients with tennis elbow seek medical attention. Local corticosteroid injections were superior to the physiotherapy regime of Cyriax. Release of the common forearm extensor origin resulted in 70% excellent or good results one year after operation and 89% at five years. Anatomical investigations and nerve conduction studies of the Radial Tunnel Syndrome supported the hypothesis that the Lateral Cubital Force Transmission System is involved in the pathogenesis of tennis elbow.

Physiological effects produced by botulinum toxin treatment of upper limb dystonia. Changes in reciprocal inhibition between forearm muscles

Patients with upper limb dystonia have abnormal reciprocal inhibition between flexor and extensor forearm muscles. To see whether botulinum toxin treatment alters segmental motor system function, we studied reciprocal inhibition between forearm flexor and extensor muscles, before and after botulinum toxin injection in forearm muscles in 12 patients with upper limb dystonia. Reciprocal inhibition was studied by conditioning the H reflex in forearm flexors with a radial nerve stimulus delivered at a range of time intervals. Botulinum toxin injection improved upper limb dystonia. Before botulinum toxin injection, the dystonic patients had a decreased second phase of reciprocal inhibition. After botulinum toxin injections this second abnormal phase of reciprocal inhibition increased. Botulinum toxin did not change the first phase of reciprocal inhibition. Botulinum toxin treatment also reduced the M wave and the H reflex by a similar amount but left the Hmax:Mmax ratio unchanged. Ample evidence has shown that the therapeutic effects of botulinum toxin in dystonia depend mainly on its neuromuscular junction blocking action. Our data now suggest a concurrent indirect effect on spinal cord circuitry, probably through the action of botulinum toxin on the intrafusal neuromuscular junction.

Nerve transfer to deltoid muscle using the nerve to the long head of the triceps, part I: an anatomic feasibility study

PURPOSE

To experimentally evaluate the feasibility of restoring the motor function of the deltoid muscle in patients with complete C5-C6 root injury (upper brachial plexus injury) by transferring the nerve to the long head of the triceps to the anterior branch of the axillary nerve through a posterior approach.

METHODS

The study was performed on shoulder girdles of 36 formalin-embalmed cadavers. The number, diameter, and length of the branches of the axillary nerve at the level of the quadrilateral space were noted. The length and diameter of the nerves to the long head and to the lateral head of triceps at the level of triangular space were recorded. The distances from the acromion angle to the bifurcation of the anterior branch of the axillary nerve, to the origins of the nerve to the long head, and to the origin of the lateral head of the triceps were recorded as well. Nerve biopsy specimens of the axillary nerve and the nerve to the long head of the triceps were obtained from 6 fresh cadavers for histomorphometric evaluation.

RESULTS

The average length of the anterior branch of the axillary nerve in this study, measured from the quadrilateral space to the innervating site, was 44.5 mm (range, 26-62 mm), and the average length of the nerve to the long head of triceps, measured from its origin to the innervating site, was 68.5 mm (range, 30-69 mm). The average diameter of the anterior branches of the axillary nerve and the nerve to the long head of the triceps were 2.1 and 1.1 mm, respectively. The average number of axon fibers in the anterior branch of the axillary nerve was 2,704 and in the nerve to the long head of the triceps was 1,233.

CONCLUSIONS

Using the acromial angle as the landmark, the combined length of the two 2 nerves was longer than the distance between them. The diameter, the number of axons, and the anatomic proximity of the nerve to the long head of the triceps make it a potential source for reinnervation of the anterior branch of the axillary nerve by direct nerve transfer without nerve grafting through posterior approach for the management of upper brachial plexus injuries.

Chronic Monteggia lesions in children. Complications and results of reconstruction

We retrospectively reviewed the results of operative treatment of chronic Monteggia lesions (Bado type I or the equivalent) with anterior radiocapitellar dislocation in seven patients. The mean age at the time of the reconstruction was six years and nine months (range, eleven months to twelve years), and the mean time from the injury to the operation was twelve months (range, five weeks to thirty-nine months). The mean duration of follow-up was four years and six months (range, two years to eleven years and three months). There were fourteen complications, including malunion of the ulnar shaft in one patient; residual radiocapitellar subluxation in two patients (one anterior and one posterolateral); radiocapitellar dislocation (dynamic anterior subluxation of the radial head in supination) in one patient; transient ulnar-nerve palsy in three patients (with residual weakness in two); partial laceration of the radial nerve in one patient; loss of the fixation in two patients; and non-union of the ulnar osteotomy site, compartment syndrome, conversion reaction, and possible fibrous synostosis of the forearm in one patient each. The patients lost a mean of 36 degrees of pronation and a mean of 27 degrees of supination of the forearm compared with the contralateral, uninjured extremity. Two patients demonstrated a loss of flexion of the elbow of 8 and 13 degrees and three had a loss of extension (mean, 15 degrees) compared with the contralateral side. There were three good, two fair, and two poor results.

Muscle weakness, paralysis, and atrophy after human cervical spinal cord injury

Muscle weakness and failure of central motor drive were assessed in triceps brachii muscles of individuals with chronic cervical spinal cord injury (SCI) and able-bodied controls. Electrical stimuli were applied to the radial nerve during rest and during triceps submaximal and maximal voluntary contractions (MVCs). The mean forces and integrated EMGs generated by SCI subjects during MVCs were significantly less than those produced by controls (P < 0.01), with 74 and 71% of muscles generating <10% control force and EMG, respectively. There was an inverse linear relationship between the evoked and voluntary forces (n = 32 muscles of SCI subjects) which, when extrapolated to zero evoked force, also showed significant whole muscle weakness for SCI compared to control subjects (P < 0. 01). Severe muscle atrophy was revealed which might reflect disuse and/or muscle denervation subsequent to motoneuron loss. Many triceps muscles of SCI subjects showed no force occlusion (n = 41) or were impossible to stimulate selectively (n = 61). Force was always evoked when the radial nerve was stimulated during MVCs of SCI subjects. The force elicited by single magnetic shocks applied to the motor cortex at Cz' during voluntary contractions of SCI subjects was also inversely related to the voluntary triceps force exerted (n = 18), but usually no force could be elicited during MVCs. Thus central motor drive was probably maximal to these muscles, and the force evoked during MVCs by below-lesion stimulation must come from activation of paralyzed muscle. SCI subjects also had significantly longer mean central nervous system (CNS) conduction times to triceps (P < 0.01) suggesting that the measured deficits reflect CNS rather than peripheral nervous system factors. Thus, the weak voluntary strength of these partially paralyzed muscles is not due to submaximal excitation of higher CNS centers, but results mainly from reduction of this input to triceps motoneurons.

Dissociation of sympathetic nerve activity in arm and leg muscle during mental stress

Mental stress, which increases blood pressure and heart rate, increases forearm blood flow but does not change calf blood flow. The purpose of this study was to determine if mental stress increases muscle sympathetic nerve activity in the leg and causes a dissociation of muscle sympathetic nerve activity in the arm and the leg. We recorded heart rate, blood pressure, and efferent sympathetic nerve activity during mental stress (4 minutes of mental arithmetic) in 13 healthy men. Microelectrodes were inserted percutaneously into a fascicle of the peroneal nerve (leg) and radial nerve (arm) to measure sympathetic discharge to muscle. In Study 1, leg muscle sympathetic nerve activity was recorded in seven subjects. Mental stress significantly increased heart rate and blood pressure. Despite the increased blood pressure (which would be expected reflexly to inhibit sympathetic nerve activity), leg muscle sympathetic nerve activity (in total integrated activity, bursts per 100 heart beats or bursts per minute) increased significantly during stress. Further, whereas heart rate and blood pressure returned to normal during recovery, leg muscle sympathetic nerve activity remained elevated during recovery. In Study 2, simultaneous recordings were made of arm and leg muscle sympathetic nerve activity in six subjects. Mental stress increased heart rate and arterial pressure. Leg muscle sympathetic nerve activity again increased significantly during stress and remained elevated during recovery. In contrast, arm muscle sympathetic nerve activity did not change during stress. However, arm muscle sympathetic nerve activity increased significantly during recovery after stress. These studies indicate that a sympathoexcitatory influence of mental stress overrides or inhibits baroreceptor control of leg sympathetic nerve activity and stress causes a dissociation of arm and leg muscle sympathetic nerve activity with increased outflow to the leg but not to the arm. These observations may contribute to differences in blood flow to arm and leg during mental stress.

Electrophysiologic findings in multifocal motor neuropathy

We performed detailed electrophysiologic studies on 16 patients with clinically defined multifocal motor neuropathy and found a wide spectrum of demyelinating features. Only five patients (31%) had conduction block in one or more nerves. However, in 15 patients (94%) at least one nerve showed other features of demyelination. We also noted a significant degree of superimposed axonal degeneration in 15 patients. Eight patients (50%) had individual nerves with pure axonal injury, despite the presence of demyelinating features in other nerves. Antiganglioside antibodies were elevated in four of five patients with conduction block and five of 11 patients without conduction block. We conclude that multifocal motor neuropathy is characterized electrophysiologically by a wide spectrum of axonal and demyelinating features. Diagnostic criteria requiring conduction block may lead to underdiagnosis of this potentially treatable neuropathy.

Upper limb tension tests as tools in the diagnosis of nerve and plexus lesions. Anatomical and biomechanical aspects

OBJECTIVE

To analyse the validity of nerve tension tests used in the diagnosis of nerve (root) and plexus lesions of the upper extremity.

DESIGN

In six arms of embalmed human bodies, in situ measurements were performed to assess the effect of nerve tension tests on the median, ulnar and radial nerves and the cords of the brachial plexus.

BACKGROUND

In clinical practice it is useful to have fast, easy and cheap tests for the diagnosis of nerve (root) lesions of the upper extremity, analogous to Lasègue's Straight Leg Raising test.Methods. The Upper Limb Tension Tests for the median, ulnar and radial nerves, as well as the Upper Limb Tension Tests combined with contralateral rotation and lateral bend of the cervical spine (Upper Limb Tension Test+) were used to generate tension to these nerves. Buckle force transducers were used to assess tensile forces in the nerves and in the medial, lateral and posterior cords of the brachial plexus.

RESULTS

Nerve tension introduced in the distal part of the median, ulnar and radial nerves was transmitted upward to the cords of the brachial plexus. Exclusively the median nerve Upper Limb Tension Test and Upper Limb Tension Test+ turned out to be sensitive and specific tension tests. Mechanical tension caused by the Upper Limb Tension Test+ was not significantly higher than that caused by the Upper Limb Tension Tests. The Upper Limb Tension Tests cannot be used to selectively stress cervical nerve roots. The findings justify investigation of exclusively the median nerve Upper Limb Tension Test and Upper Limb Tension Test+ on their clinical validity.

RELEVANCE

Before nerve tension tests for the median, ulnar and radial nerves can be introduced to clinical practice it is necessary to assess their validity quantitatively.

Rupture of the distal biceps brachii tendon: conservative treatment versus anatomic reinsertion--clinical and radiological evaluation after 2 years

INTRODUCTION

Distal biceps tendon rupture is a relatively rare injury. It commonly occurs in the dominant extremity of middle-aged men during an excessive eccentric tension as the arm is forced from a flexed position, while it is rarely observed during sport activities. Many techniques, including non-operative and surgical option, have been described for the treatment of a ruptured distal biceps tendon, but there is still considerable controversy about the management of choice.

MATERIAL AND METHODS

Nine patients affected with traumatic distal tendon ruptures of the biceps brachii were followed-up for a minimum of 24 months. Five patients underwent surgery (two-incision technique) and four patients were treated conservatively. Tendon readaptation to its origin was done by a suture metal anchor. Outcome was evaluated based on the physical examination, radiographic analysis and the SECEC elbow score.

RESULTS

The SECEC elbow score results show that every single item result is in favour of surgical treatment. On measurements of motion, we found a slight flexion-extension deficit in two patients, but reduced supination in six patients and reduced pronation in four. Two patients had postoperative dysfunction of the deep branch of the radial nerve. Radiographic examination showed heterotopic bone formation on the radial tuberosity around the presumed insertion of the reattached tendon in 2 of 5 patients and ectopic ossification more proximally in the area of the biceps muscle

CONCLUSION

Our findings confirm the view that anatomic repair of distal biceps tendon rupture provides consistently good results and early anatomic reconstruction can restore strength and endurance for the elbow.

A useful electrophysiologic parameter for diagnosis of carpal tunnel syndrome

In 43 patients (50 hands) with clinical manifestations of mild-moderate carpal tunnel syndrome (CTS) and 36 healthy volunteers (40 hands), orthodromic sensory nerve conduction velocity (SNCV) was measured with surface electrodes in the median nerve between the third digit and palm and between the palm and wrist. These figures were used to calculate the ratio of distal to proximal conduction (distoproximal ratio). All 90 hands were also subjected to other nerve conduction studies used for diagnosis of CTS. All control hands presented distoproximal ratios < 1.0 reflecting higher conduction rates in the proximal segment. In contrast, 49 of 50 CTS hands (98%) presented reversed ratios (> 1.0) indicating compromised proximal conduction. The sensitivity of this test was significantly greater than that of other methods evaluated, including comparative studies and segmental study of the palm-wrist portion of the median nerve. Segmental study of median SNCV with calculation of the distoproximal ratio is a sensitive technique for diagnosis of CTS in patients with normal findings in standard nerve conduction studies.

Reciprocal inhibition in writer's cramp

We studied the inhibition of median H-reflexes by conditioning stimuli on the radial nerve in 13 patients with writer's cramp, eight of the simple type and five of the dystonic type, and in 14 normal volunteers. The patients and controls were right-handed, and their right arms were studied. Asymptomatic left arms were also studied in nine of 13 patients. In the control group we identified three periods of inhibition, with maximum peaks at conditioning-test intervals of 0 ms (41 +/- 17%), 20 ms (40 +/- 13%), and 100 ms (36 +/- 20%). In the patient group, the amplitudes of inhibition of these three periods in both arms were significantly less than those in the control group. However, there were no significant differences in the amplitudes of inhibition of these three periods between symptomatic and asymptomatic arms. There were also no significant differences between simple and dystonic writer's cramps. Our results indicate that the attenuation of reciprocal inhibition was present not only in symptomatic arms but also in asymptomatic arms of patients with writer's cramp. The defect of reciprocal inhibition in the asymptomatic hand has never been documented. We suggest that the preexistent electrophysiological abnormality may provide an explanation for the development of hand cramp after shifted writing.

Quantification of fingertip force reduction in the forefinger following simulated paralysis of extensor and intrinsic muscles

Objective estimates of fingertip force reduction following peripheral nerve injuries would assist clinicians in setting realistic expectations for rehabilitating strength of grasp. We quantified the reduction in fingertip force that can be biomechanically attributed to paralysis of the groups of muscles associated with low radial and ulnar palsies. We mounted 11 fresh cadaveric hands (5 right, 6 left) on a frame, placed their forefingers in a functional posture (neutral abduction, 45 degrees of flexion at the metacarpophalangeal and proximal interphalangeal joints, and 10 degrees at the distal interphalangeal joint) and pinned the distal phalanx to a six-axis dynamometer. We pulled on individual tendons with tensions up to 25% of maximal isometric force of their associated muscle and measured fingertip force and torque output. Based on these measurements, we predicted the optimal combination of tendon tensions that maximized palmar force (analogous to tip pinch force, directed perpendicularly from the midpoint of the distal phalanx, in the plane of finger flexion-extension) for three cases: non-paretic (all muscles of forefinger available), low radial palsy (extrinsic extensor muscles unavailable) and low ulnar palsy (intrinsic muscles unavailable). We then applied these combinations of tension to the cadaveric tendons and measured fingertip output. Measured palmar forces were within 2% and 5 degrees of the predicted magnitude and direction, respectively, suggesting tendon tensions superimpose linearly in spite of the complexity of the extensor mechanism. Maximal palmar forces for ulnar and radial palsies were 43 and 85% of non-paretic magnitude, respectively (p<0.05). Thus, the reduction in tip pinch strength seen clinically in low radial palsy may be partly due to loss of the biomechanical contribution of forefinger extrinsic extensor muscles to palmar force. Fingertip forces in low ulnar palsy were 9 degrees further from the desired palmar direction than the non-paretic or low radial palsy cases (p<0.05).

Disputed radial tunnel syndrome

True neurogenic radial tunnel syndrome is an uncommon condition caused by entrapment of the radial or posterior interosseous nerve in the radial tunnel and is usually easily identifiable by focal motor weakness in the distribution of the posterior interosseous nerve. Roles and Maudsley, analogizing to carpal tunnel syndrome, believed "radial tunnel syndrome" had a different presentation: proximal forearm pain and tenderness in the region of the supinator muscle. However, their patients lacked weakness or other neurologic deficit. They and subsequent surgeons have decompressed the radial nerve to treat forearm pain and tenderness, even though it is debatable whether radial nerve entrapment causes the forearm discomfort. The term "radial tunnel syndrome" is best reserved for the truly neurogenic cases. Surgical approaches to "persistent tennis elbow" should be assessed in a controlled fashion, rather than adopted on the basis of a flawed analogy to carpal tunnel syndrome.

Rate of recovery in motor and sensory fibres of the radial nerve: clinical and electrophysiological aspects

Electromyography and conduction studies in motor and sensory fibres were performed in 58 patients with different types of radial nerve injury. The site of nerve injury was predicted by clinical and electromyographic findings and correlated with changes in conduction, thereby permitting a more exact classification of the type of nerve injury. In patients with Saturday-night palsy, there was considerable slowing of conduction in both motor and sensory fibres across the presumed site of the lesion with return to normality within six to eight weeks. These observations suggest that local demyelination is the cause of nerve palsy. There were changes in sensory conduction even when there was no sensory deficit clinically, with no difference in susceptibility of motor and sensory fibres to ischaemia. In patients with radial nerve palsy secondary to fracture of the humerus, out-growth in motor and sensory fibres was equal and estimated to be about 1 mm per day. When the radial nerve palsy was attributed to traction or mild blunt injury the site of lesion was based on clinical and electromyographic findings. The rate of conduction in motor and sensory fibres was normal, suggesting that axonal damage was the cause of paresis, with sparing of some of the fastest conducting fibres.

The location of conduction abnormalities in human entrapment neuropathies

Direct stimulation of 23 median, 13 ulnar and 2 peroneal nerves at the time of surgical exploration has been used to locate, and characterize the conduction abnormalities in the nerves. The most frequent location of the major conduction abnormalities in the median nerve was in the first 1-2 cm distal to the origin of the carpal tunnel. In the ulnar nerve the important conduction abnormalities were located most frequently in the segments 1 cm proximal and distal to the medial epicondyle. In the peroneal nerve the major conduction abnormalities occurred proximal or distal to the entry point of the common peroneal nerve into the peroneus longus muscle.

Short-latency somatosensory-evoked potentials from radial, median, ulnar, and peroneal nerve stimulation in the assessment of cervical spondylosis. Comparison with conventional electromyography

A study of data on 30 patients with cervical spondylosis was carried out to determine whether short-latency somatosensory-evoked responses (SEPs) to median, ulnar, radial, and peroneal nerve stimulation provided additional information to that obtained by electromyography (EMG), late responses, and peripheral conduction studies. Peripheral studies, EMG results and SEPs were within normal limits in ten patients with pain, but without objective neurological deficit. By contrast, of ten patients who had objective signs of root compression, conventional EMG results were normal in nine, but abnormalities of the SEPs from radial nerve stimulation were obtained in only five patients, and were normal from ulnar and median nerve stimulation. In ten patients with clinical features of myelopathy, seven had abnormal median SEPs and all had abnormal peroneal SEPs, whereas EMG results were abnormal in only five patients. It is suggested that SEPs and EMG are both of limited use in patients with only symptoms of root compression. In patients with signs of root compression, EMG is the most sensitive procedure; however, some additional information can be obtained from superficial radial SEPs. In patients with cervical myelopathy, SEP was the most useful procedure, especially when upper and lower limbs were studied.

Radial nerve lesions associated with fractures of the humeral shaft

Radial nerve palsy associated with a fracture of the shaft of the humerus is a relatively common injury. Out of 91 radial nerve injuries, operated upon in the Neurosurgical University Clinic in Belgrade from 1979 to 1988, 37 were associated with fractures of the humeral shaft or their surgical treatment. These fractures were previously treated in other medical units. In all cases a microsurgical reconstruction of the radial nerve was done: an interfascicular neurolysis in 24 cases and interfascicular grafting in 13 cases. A useful functional recovery was obtained in 91.9 per cent of the cases. Timing of nerve exploration and repair, as a main problem, is discussed.

Treatment of end-neuromas, neuromas-in-continuity and scarred nerves of the digits by proximal relocation

This paper reports the results of treatment by proximal relocation of 104 painful nerves in 57 digits in 48 patients. These included 86 digital nerves and 18 terminal branches of the superficial radial nerve and the dorsal branch of the ulnar nerve. Eighty-three were end-neuromas and 14 were neuromas-in-continuity, of which nine followed nerve repair and five occurred following a closed crush injury. Seven were painful as a result of tethering in scarred tissue. Eighty nerves (77%) required a single relocation and 24 (23%) required more than one operation. Ninety-eight per cent of nerve relocations achieved complete pain relief at the primary site. One patient had mild pain on pressure at the primary site after relocation of two nerves from this site. Over 90% of the nerves had no spontaneous pain, pain on movement or hypersensitivity of the overlying skin at the final site of relocation. However, the incidence of mild or no pain on direct pressure at the site of nerve relocation was lower at 83% as relocated nerves, although traumatized less often at the sites chosen for relocation, can still be painful on direct pressure.

Sural/radial amplitude ratio in the diagnosis of mild axonal polyneuropathy

As proximal nerves are relatively spared in length-dependent, axonal polyneuropathy, we theorized that a sural/radial amplitude ratio (SRAR) might be a sensitive indicator of mild polyneuropathy. In this study, sural amplitudes and SRARs in patients with signs of mild axonal polyneuropathy were compared to those of normal, age-matched control subjects. Sural and radial sensory responses were measured in a standard fashion in all subjects. Thirty polyneuropathy patients had an average SRAR of 0.29 as compared to 0.71 for the 30 normal subjects. An SRAR of less than 0.40 was a strong predictor of axonal polyneuropathy, with 90% sensitivity and 90% specificity, as compared to an absolute sural amplitude of less than 6.0 microV, which had sensitivity of only 66%. Additionally, unlike the sural amplitude, the ratio did not vary significantly with age. We conclude that the SRAR is a sensitive, specific, age-independent electrodiagnostic test for mild axonal polyneuropathy.

Evaluation of experimental spinal cord injury using cortical evoked potentials

✓ Experiments were performed to determine if changes in cortical evoked responses could be used to predict the extent of the neurological deficits following spinal cord injury by sudden inflation of a Fogarty balloon in the epidural space cephalad to a laminectomy. The cortical responses to stimulation of the posterior tibial nerve were recorded over the sigmoid gyrus at various times following the lesion and compared with the control response. Severe, irreversible neurological deficits occurred in cats in which the cortical response either could not be evoked immediately after injury or disappeared rapidly during this period. At the end of at least 6 weeks following injury, all of these animals were paraplegic and showed severe cystic degeneration of the spinal cord. In animals in which the post-injury cortical response did not completely disappear, only mild changes were observed in a spinal cord 6 weeks following injury. This technique may be helpful in ascertaining the severity and irreversibility of a traumatic spinal cord lesion; because the technique is simple, the method may prove helpful in the clinical management of patients with spinal cord injury.

Radial tunnel syndrome: diagnosis and management

This study presents a review of 26 cases of radial tunnel syndrome in 25 patients seen in a single hand consultant's practice over a period of 2.5 years. The protocol for diagnosis was the reproduction of patient's symptoms on pressure over a palpable tender spot along the course of the radial tunnel, painful resisted supination or resisted middle finger extension, all of which were abolished on infiltration of the tender area with a local anaesthetic solution. The presence of at least two out of three objective signs was necessary for the diagnosis. Initially all cases were treated conservatively, by steroid injection in 25 and physiotherapy in one, with long-term relief of pain in 16. Nine failures were treated surgically, with complete relief of pain in seven. Radial tunnel syndrome should be considered in the differential diagnosis of pain around the hand and or elbow.