High Median Nerve Injury: Motor and Sensory Nerve Transfers to Restore Function

This article describes the clinically significant motor and sensory deficits that follow high median nerve injuries and addresses the indications, limitations, and outcomes of nerve transfers, when striving to overcome the deficits these patients' experiences. Preferred surgical reconstructive strategy using motor and sensory nerve transfers, and surgical techniques used to perform these transfers, are described.

Variation in nerve autograft length increases fibre misdirection and decreases pruning effectiveness. An experimental study in the rat median nerve

OBJECTIVES

In the clinical set, autologus nerve grafts are the current option for reconstruction of nerve tissue losses. The length of the nerve graft has been suggested to affect outcomes. Experiments were performed in the rat in order to test this assumption and to detect a possible mechanism to explain differences in recovery.

METHODS

The rat median nerve was repaired by ulnar nerve grafts of different lengths. Rats were evaluated for 12 months by behavioural assessment and histological studies, including ATPase myofibrillary histochemistry and retrograde neuronal labelling.

RESULTS

It was demonstrated that graft length interferes in behavioural functional recovery that here correlates to muscle weight recovery. Short nerve grafts recovered faster and better. Reinnervation was not specific either at the trunk level or in the muscle itself. The normal mosaic pattern of Type I muscle fibres was never restored and their number remained largely augmented. An increment in the number of motor fibres was observed after the nerve grafting in a predominantly sensory branch in all groups. This increment was more pronounced in the long graft group. In the postoperative period, about a 20% reduction in the number of misdirected motor fibres occurred in the short nerve graft group only.

CONCLUSION

Variation in the length of nerve grafts interferes in behavioural recovery and increases motor fibres misdirection. Early recovery onset was related to a better outcome, which occurs in the short graft group.

Clinical findings in C5-C6 and C5-C7 root palsies with brachial plexus traction lesions

Stretch injuries of the C5-C7 roots of the brachial plexus traditionally have been associated with palsies of shoulder abduction/external rotation, elbow flexion/extension, and wrist, thumb, and finger extension. Based on current myotome maps we hypothesized that, as far as motion is concerned, palsies involving C5-C6 and C5-C7 root injuries should be similar. In 38 patients with upper-type palsies of the brachial plexus, we examined for correlations between clinical findings and root injury level, as documented by CT tomomyeloscan. Contrary to commonly held beliefs, C5-C7 root injuries were not associated with loss of extension of the elbow, wrist, thumb, or fingers, but residual hand strength was much lower with C5-C7 vs C5-C6 lesions.

Muscle fiber type reorganization and behavioral functional recovery of rat median nerve repair with vascularized or conventional nerve grafts

In 1921, Ney introduced the concept of nerve grafts with preservation of the vascular blood supply. Today, over 70 years later, the use of vascularized nerve grafts in clinical practice is still controversial. Although the results of experiments with vascularized and conventional nerve grafts have been compared on the basis of electrophysiological and histological observations, the literature includes no vaJid comparison of the clinical and behavioral significance of these results. Therefore, in the experiments reported here, the rat median nerve was repaired using either a vascularized or a conventional ulnar nerve graft. The rates behavior between 0 and 360 days after surgery was assessed by the grasping test. Nienty-five, 120, 150, 210 and 360 days after surgery rats were submitted to retrograde labeling studies and muscle samples were removed and studied using routine hematoxilin-eosin and ATPase histochemistry. The present study provides evidence that autografting is a reliable procedure for nerve repair. Motor axons were able to reinnervate and largely respecify muscle properties. Reinnervation was not selective either at the nerve trunk level or at the muscle fiber. A mechanism of collateral pruning might have been present in the early phases of reinnervation. This mechanism was, however, self limiting and unable to correct all wrong projections. A mechanism of terminal sprouting was in part responsible for time-related improvement in muscle force recovery. While the present study does provide evidence that recovery was 20% faster in rats with vascularized grafts than in those with conventional grafts (P < 0.0001), it does not, however, provide evidence for better functional recovery in long-term assessment.

Distal sensory nerve transfers in lower-type injuries of the brachial plexus

PURPOSE

To report the results of sensory nerve transfers to reconstruct sensation on the ulnar side of the hand in lower-type palsies of the brachial plexus.

METHODS

From 2007 to 2009, we operated on 6 men and 2 women with a lower-type injury of the brachial plexus and observed them for a minimum of 24 months. The mean interval between the injury and surgery was 8 months (SD ± 8.6 mo). Before surgery, we documented anesthesia on the ulnar side of the hand in all patients. Donor nerves included cutaneous branches of the median nerve to the palm (n = 5) or the palmar cutaneous branch of the median nerve (n = 3). The ulnar proper digital nerve of the little finger was the recipient nerve. We evaluated sensory recovery by assessing static 2-point discrimination and sensation to Semmes-Weinstein monofilaments.

RESULTS

According to the British Medical Council system of evaluation, 5 patients scored S3 and 3 scored S3+.

CONCLUSIONS

In lower-type injuries of the brachial plexus, transfer of median nerve branches that innervate the palm of the hand to the ulnar proper digital nerve of the little finger predictably restored protective sensation on the ulnar side of the hand.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Results and current approach for Brachial Plexus reconstruction

We review our experience treating 335 adult patients with supraclavicular brachial plexus injuries over a 7-year period at the University of Southern Santa Catarina, in Brazil. Patients were categorized into 8 groups, according to functional deficits and roots injured: C5-C6, C5-C7, C5-C8 (T1 Hand), C5-T1 (T2 Hand), C8-T1, C7-T1, C6-T1, and total palsy. To restore function, nerve grafts, nerve transfers, and tendon and muscle transfers were employed. Patients with either upper- or lower-type partial injuries experienced considerable functional return. In total palsies, if a root was available for grafting, 90% of patients had elbow flexion restored, whereas this rate dropped to 50% if no roots were grafted and only nerve transfers performed. Pain resolution should be the first priority, and root exploration and grafting helped to decrease or eliminate pain complaints within a short time of surgery.

Transfer of supinator motor branches to the posterior interosseous nerve to reconstruct thumb and finger extension in tetraplegia: case report

We treated a patient with tetraplegia who had paralysis of thumb and finger extension by transferring supinator motor branches to the posterior interosseous nerve. Surgery was performed bilaterally, 7 months after a spinal cord injury. Six months after surgery, with the wrist in neutral, extension of the thumb and finger were almost full, bilaterally. In tetraplegic patients with strong wrist extensors, supinator motor branch transfer is a promising new alternative for the reconstruction of thumb and finger extension.

Transfer of the supinator muscle to the extensor pollicis brevis for thumb extension reconstruction in C7-T1 brachial plexus palsy

With C7-T1 brachial plexus injuries, finger motion is absent while shoulder, elbow and wrist function are largely preserved. Previously, we have reconstructed finger flexion by transferring the brachialis muscle to the flexor digitorum profundus and flexor pollicis longus; and we have restored extension of thumb and finger by transferring the motor nerve to the supinator to the posterior interosseous nerve, which is only feasible in fresh injuries. We describe the transfer of the supinator muscle to the extensor pollicis brevis to reanimate thumb extension in patients with long standing C7-T1 brachial plexus palsy.

Lengthening of subscapularis and transfer of the lower trapezius in the correction of recurrent internal rotation contracture following obstetric brachial plexus palsy

An internal rotation contracture is a common complication of obstetric brachial plexus palsy. We describe the operative treatment of seven children with a recurrent internal rotation contracture of the shoulder following earlier corrective surgery which included subscapularis slide and latissimus dorsi transfer. We performed z-lengthening of the tendon of the subscapularis muscle and transferred the lower trapezius muscle to the infraspinatus tendon. Two years postoperatively the mean gain in active external rotation was 47.1 degrees, which increased to 54.3 degrees at four years. Lengthening of the tendon of subcapularis and lower trapezius transfer to infraspinatus improved the range of active external rotation in patients who had previously had surgery for an internal rotation contracture.

Lower trapezius muscle transfer for reconstruction of elbow extension in brachial plexus injuries

Elbow extension is a prerequisite for adequate hand position. Muscle transfers are often employed in partial injuries of the brachial plexus, when neurological surgery is unlikely to achieve desired results. The posterior deltoid and latissimus dorsi are the two muscles most commonly used for transfer but there are few alternatives when these two muscles are paralysed. We now report on the successful transfer of the lower trapezius muscle to reconstruct triceps function in three patients with longstanding lesions of the brachial plexus that had not been previously treated surgically.

Pain after avulsion injuries and complete palsy of the brachial plexus: the possible role of nonavulsed roots in pain generation

OBJECTIVE

Pain after complete brachial palsy has been attributed to the deafferentation of the spinal cord subjected to root avulsion. However, the large majority of patients have at least one nonavulsed root. We postulated that pain, be it subacute or chronic, originates in the stump of the nonavulsed roots.

METHODS

Thirty-six patients underwent brachial plexus grafting within 8 months of their initial injury. Ten other patients with palsy that had lasted for more than 2 years underwent selective, computed tomography-guided anesthetic blocks of the nonavulsed root. Pain was evaluated at different intervals, using a numerical scale ranging from 0 (no pain) to 10 (severe pain).

RESULTS

In all groups, pain decreased substantially or disappeared after a local anesthetic block or grafting. In the patients who underwent grafting, pain reduction was noted the first day after surgery in 56% of the 36 patients. Three weeks after surgery, pain decreased dramatically, by 80% (P < 0.001). By 12 months after surgery, pain had decreased by 90%, and within 24 months, by 95%. Only the difference between 3 weeks and 24 months after surgery was significant (P < 0.001). At final evaluation, 80% of the patients receiving grafts reported either no or minimal pain.

CONCLUSION

Our data suggest that nonavulsed roots mediate pain in subacute and chronic complete brachial plexus palsy.

Flexor tendon grafting using a plantaris tendon with a fragment of attached bone for fixation to the distal phalanx: a preliminary cohort study

PURPOSE

Secure methods of graft attachment ensure safe early motion after flexor tendon grafting. This has been achieved at the proximal graft juncture using Pulvertaft's technique. For secure distal attachment, we investigate the results of flexor tendon grafting using the plantaris tendon with a fragment of attached bone fixed with a screw to the distal phalanx.

METHODS

Thirteen digits from 10 patients with longstanding flexor tendon injuries in zone II had surgical reconstruction. A plantaris tendon-bone graft was attached to the distal phalanx using a mini-screw. This was followed by immediate active motion. At 3 and 8 months after surgery, total active motion was calculated as the sum of the degrees of active flexion in the proximal and distal interphalangeal joints minus the sum of the degrees of extension deficits for each of these joints. The results of total active motion were compared to the normal contralateral digit.

RESULTS

Three months after surgery, the mean rate of recovery, relative to the normal contralateral finger, was 74%, whereas 8 months after surgery, this value was 70%. This difference was statistically significant. There were no failures or poor results (ie, less than 50% recovery).

CONCLUSIONS

The tendon-bone plantaris graft employed here ensured immediate active motion and early use of the involved hand in daily activities.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Triceps Motor Nerve Branches as a Donor or Receiver in Nerve Transfers

Objective:

The pattern of triceps innervation is complex and, as yet, has not been fully elucidated. The purposes of this study were 1) to clarify the anatomy of the triceps motor branches, and 2) to evaluate their possible uses as a donor or receiver for nerve transfer.

Methods:

The radial nerve and its motor and cutaneous branches were bilaterally dissected from the axilla and posterior arm regions of 10 embalmed cadavers.

Results:

A single branch innervates the triceps long head, whereas double innervation was identified for the lateral and medial heads. The upper branch to the lateral head originated from the radial nerve, whereas the lower branch to the lateral head stemmed from the lower medial head motor branch, which ultimately innervated the anconeus muscle. Both the long head and the upper medial head motor branches originated in the axillary region in the vicinity of the latissimus dorsi tendon.

Conclusion:

Each of the triceps’ motor branches might be used as a donor for transfer. The triceps long head motor branch should be used preferentially when the intention is to establish triceps reinnervation.

Treatment of scaphoid non-unions by a palmar approach with vascularised bone graft harvested from the thumb

Ten patients with scaphoid non-unions which had been present for longer than 2 years were treated using a vascularised bone graft harvested from the thumb and pedicled on the first dorsal metacarpal artery. Bone harvesting and grafting were performed by a single palmar approach. Concomitant cancellous bone graft was not used. Bone healing was confirmed by CT scans in nine of the ten patients. Persistence of the non-union was observed in one patient who was the oldest in this series, had the longest standing non-union and was a heavy smoker. Twelve months after surgery, nine of the ten patients had significant pain relief with an improved range of motion and grip strength.

The course of aberrant reinnervation following nerve repair with fresh or denatured muscle autografts

Denatured muscle grafts obtained by freeze thawing have been proposed to replace losses in the peripheral nerves. In the present report, we compare the performance of such grafts with fresh grafts in the rat median nerve. A long-term effect of muscle interposition on reinnervation was studied by behavioral assessment, muscle ATPase histochemistry, and retrograde labeling of motoneurons. There was no difference in grasping strength recovery between fresh and denatured 10-mm-long muscle grafts. Recovery was delayed and incomplete. Twelve months after surgery, only 50% of the normal grasping strength was attained. Grasping recovery was not observed in the 20-mm-long graft groups. Pathway reinnervation was non-specific with a huge amount of motor fiber misdirection. A decrease in the number of misdirected motor fibers occurred with time and activity recovery. Muscle reinnervation was not specific with disturbance of the mosaic pattern and type-grouping formation. Preference of type I axons for reinnervating deeper zones was observed. Type I aberrant reinnervation was demonstrated in the muscle periphery. The mosaic distribution of type I and II muscle fibers was not stable, and readjustments were observed with time, correlating with grasping improvement. During grasping strength recovery, there was a decrease in the number of type I fibers peripherally located and an increase of those deeply disposed. A time- and activity-related recovery was associated with readjustment in the pathways and muscle fiber rearrangement. We suggest that muscle activity generates specificity.

Pharmacological characterisation of the rat brachial plexus avulsion model of neuropathic pain

Recently, our laboratory has proposed the avulsion of rat brachial plexus as a new and reliable model for the study of neuropathic pain. In this model, the neuropathy can be detected even at distant sites from the injury, both in ipsilateral and contralateral hindpaws. The purpose of this study was to pharmacologically characterise this behavioural model of persistent peripheral neuropathic pain by assessing the effects of several analgesic drugs currently used in clinical practice. For this purpose, the effects of these drugs on the mechanical and cold allodynia were analysed 20-40 days after rat brachial plexus avulsion. Injection of saline, administered by the same route as the other drugs, did not significantly affect the nociceptive threshold either in sham-operated or in neuropathic rats. However, administration of the opioid analgesic morphine (5 mg/kg, s.c.), the alpha2 adrenoceptor agonist clonidine (300 microg/kg, i.p.), the NMDA receptor antagonist ketamine (25 mg/kg, i.p.) or the anticonvulsant drug gabapentin (70 mg/kg, p.o.) consistently reduced both mechanical and cold allodynia following avulsion of rat brachial plexus. The administration of the selective COX-2 inhibitor celecoxib (10 mg/kg, p.o.) blocked mechanical allodynia, but not cold allodynia, whereas the sodium channel blocker lidocaine (40 mg/kg, i.p.) attenuated only cold allodynia. The non-steroidal anti-inflammatory drug diclofenac (100 mg/kg, i.p.), the steroidal anti-inflammatory dexamethasone (1.5 mg/kg, i.p.) and the antidepressant imipramine (10 mg/kg, i.p.) all failed to significantly attenuate both mechanical and cold allodynia in the rats following avulsion of brachial plexus. These findings suggest that avulsion-associated mechanical and cold allodynia, two classic signs of persistent neuropathic pain, were consistently prevented by several analgesics currently available in clinical practice, namely morphine, clonidine, ketamine and gabapentin, and to a lesser extent by celecoxib and lidocaine. Therefore, this new proposed model of persistent nociception seems to be suitable for the study of the underlying mechanisms involved in neuropathic pain and for the identification of potential clinically relevant drugs to treat this aspect of peripheral neuropathy.

Avulsion injury of the rat brachial plexus triggers hyperalgesia and allodynia in the hindpaws: a new model for the study of neuropathic pain

In the present study, we sought to characterise a behavioural model of persistent peripheral neuropathic pain produced by avulsion of the right brachial plexus in rats. In addition, we compared the effects of avulsion with those of ligation or crush injury of the brachial plexus. Avulsion and, to a lesser extent, ligation and crushing of brachial plexus caused a long-lasting (up to 90 days) and highly reproducible mechanical hyperalgesia, in both ipsilateral and contralateral hindpaws. However, the same injury did not produce thermal hyperalgesia. The avulsion and, to a lesser extent, ligation and crushing of the brachial plexus elicited a significant and long-lasting (up to 90 days) ipsilateral and contralateral cold and mechanical allodynia. Furthermore, the brachial plexus injury caused a significant decrease in functional activity of the forepaws as assessed in the grasping strength test, but did not alter the locomotor activity of the rats in the open field test in comparison with control or sham groups. Taken together these results show that avulsion of the brachial plexus in rat produces persistent mechanical and cold allodynia and mechanical hyperalgesia, and might represent a valuable method for understanding the mechanisms underlying the aetiology of neuropathic pain.

Hemidigital resection with collateral ligament transplantation in the treatment of macrodactyly: a case report

Macrodactyly is a rare congenital anomaly of the hand that is difficult to treat. We describe a new technique consisting of hemidigital, longitudinal, and transverse en bloc resection with collateral ligament transplantation to the proximal interphalangeal joint that we used in a case of macrodactyly. Four years after the procedure the digit's appearance was largely improved with preservation of complete motion at the proximal interphalangeal joint. Transplantation of the collateral ligament ensured a stable joint. Fingertip sensibility was maintained.

Cross-chest radial nerve transfer in brachial plexus injuries. Experimental and anatomical basis

Brachial plexus avulsion injuries are devastating injuries to the upper limb, and nerve transfer remains the only option in reconstruction. Despite the encouraging results concerning recovery of shoulder and elbow function, no option is available for treatment of the paralytic hand. In rats, we sectioned the radial nerve in the elbow region and transferred it across the chest to reinnervate the lesioned contralateral medial cord of the brachial plexus. Rats were then evaluated for motor and sensory recovery, electrophysiologically, behaviorally and morphologically. Forepaw functional recovery was estimated to be 90%. In cadavers, the radial nerve and profunda brachii artery were dissected. It was observed that the radial nerve vascularized by the profunda brachii artery was able to reach the contralateral brachial plexus distal to the shoulder region without nerve grafts. After sectioning the radial nerve, sensory loss is minimal and motor palsy can be easily restored by tendon transfers. The results of tendon transfer for radial nerve palsy are better than for any other nerve. Cross-chest radial nerve transfer might be of clinical interest in the reconstruction of hand function in entire injury to the brachial plexus.