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Carel F. E. Hoffmann, Enrico Marani, J. Gert van Dijk, Wim V. D. Kamp and Ralph T. W. M. Thomeer

A vulsion of one or more roots of the spinal cord occurs in approximately 70% of severe brachial plexus traction injuries in humans. 30 In contrast with spinal nerve ruptures that are currently repaired according to established surgical principles, 25, 29, 30, 42 restoration of function after avulsion cannot be achieved by local repair. In these cases, nerve transfers 14, 32, 42 and musculotendinous transpositions 31 can improve the outcome, but overall functional results remain disappointing. Innovative techniques of repair are needed to ameliorate the

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Martijn J. A. Malessy and Ralph T. W. M. Thomeer

R estoration of elbow flexion is the primary goal in treating patients with severe brachial plexus injuries. Several intraplexal grafting procedures can be used depending on the availability of proximal nerve stumps and, in addition, muscle—tendon transposition may be performed. 4, 20 Extra—intraplexal nerve transfers are used when spinal roots are avulsed and proximal stumps are not available. 30 Several studies on intercostal nerve (ICN) transfer have reported the reanimation of the paralyzed biceps muscle. 11, 13, 14, 19, 21, 24, 26–28, 38, 42 However

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Martijn J. A. Malessy, Ralph T. W. M. Thomeer and J. Gert van Dijk

S evere traction lesions of the brachial plexus frequently result in root avulsions. In these instances, reconstructive surgery aimed at restoration of the original neural connections is not possible because proximal nerve stumps are not available. To regain at least some function, the nerve transfer technique can be applied, that is, a nerve with intact continuity to the central nervous system (CNS), the donor nerve, is transected and coapted to brachial plexus structures originating from the avulsed roots, the recipient nerve. It has been convincingly

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Martijn J. A. Malessy, Sjoerd G. van Duinen, Hans K. P. Feirabend and Ralph T. W. M. Thomeer

R apid and violent traction to the brachial plexus may cause extensive loss of continuity of nerve fibers. Characteristically, the damage is distributed along the length of the nerve and may involve entire segments. 33 In addition, secondary retrograde changes may further reduce the number of viable axons. 25 The extent of nerve defects necessitates the use of long nerve grafts, which in combination with inevitable fascicular mismatching negatively influences the outcome of repair. 34 Although the efficacy of nerve grafting in improving the outcome in severe

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Martijn J. A. Malessy, Carel F. E. Hoffmann and Ralph T. W. M. Thomeer

T raction injuries of the brachial plexus may result in nerve rupture and root avulsion. In reconstructing the plexus, proximal spinal nerve stumps are used as lead outs for the grafts. Extra—intraplexal nerve transfers can be applied when spinal roots are avulsed from the cord and the number of proximal stumps available is limited. 24 Because the results of grafting are superior to those of transfer, grafts are applied preferentially in pursuing the main goals of reconstruction. 2, 16 Restoration of function has been reported in humans after reimplantation of

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Neurosurgical Forum: Letters to the Editor To The Editor Madjid Samii , Hannover, Germany 1068 1069 In their article (Malessy MJA, Hoffmann CFE, Thomeer RTWM: Initial report on the limited value of hypoglossal nerve transfer to treat brachial plexus root avulsions. J Neurosurg 91: 601–604, October, 1999), Dr. Malessy and coauthors describe the use of hypoglossal nerve as a donor nerve for neurotizations in brachial plexus injuries. They investigated 14 patients in whom the 12th cranial nerve was used as the donor nerve to reconstruct different roots and

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Neurosurgical Forum: Letters to the Editor To The Editor Ralph T. W. M. Thomeer , M.D., Ph.D. Martijn J. A. Malessy , M.D., Ph.D. Enrico Marani , Ph.D. Leiden University Medical Center Leiden, The Netherlands 138 139 Abstract Object. The authors review the first series of 10 cases in which injured intraspinal brachial plexus were surgically repaired. They describe the technique of spinal cord implantation or repair of ruptured nerve roots, as well as patient outcome. Methods

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Martijn J. A. Malessy, Dick Bakker, Ad J. Dekker, J. Gert van Dijk and Ralph T. W. M. Thomeer

I n severe brachial plexus traction lesions including C-6 root avulsions, the transfer of ICNs to the MCN can be applied to regain biceps function. 19 In this technique, the third through fifth ICNs are dissected free, transected close to the sternum, tunneled to the axilla, and coapted to the MCN. Normally, corticospinal neurons that ultimately project to the intercostal muscles are active during the execution of motor programs for respiration and/or posture control, effected through intercostal motor neurons and muscles. After transfer, central ICN

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Martijn J. A. Malessy, Godard C. W. de Ruiter, Kees S. de Boer and Ralph T. W. M. Thomeer

Object

The aim of this retrospective study was to evaluate the restoration of shoulder function by means of supra-scapular nerve neurotization in adult patients with proximal C-5 and C-6 lesions due to a severe brachial plexus traction injury (BPTI). The primary goal of brachial plexus reconstructive surgery was to restore the biceps muscle function and, secondarily, to reanimate shoulder function.

Methods

Suprascapular nerve neurotization was performed by grafting the C-5 nerve in 24 patients and by accessory or hypoglossal nerve transfer in 29 patients. Additional neurotization involving the axillary nerve could be performed in 18 patients.

Postoperative needle electromyography studies of the supraspinatus, infraspinatus, and deltoid muscles showed signs of reinnervation in most patients; however, active glenohumeral shoulder function recovery was poor. In nine (17%) of 53 patients supraspinatus muscle strength was Medical Research Council (MRC) Grade 3 or 4 and in four (8%) infraspinatus muscle power was Grade 3 or 4. In 18 patients in whom deltoid muscle reinnervation was attempted, MRC Grade 3 or 4 function was demonstrated in two (11%). In the overall group, eight patients (15%) exhibited glenohumeral abduction with a mean of 44 ± 17° (standard deviation [SD]) (median 45°) and four patients (8%) exhibited glenohumeral exorotation with a mean of 48 ± 24° (SD) (median 53°). In only three patients (6%) were both functions regained.

Conclusions

The reanimation of shoulder function in patients with proximal C-5 and C-6 BPTIs following supra-scapular nerve neurotization is disappointingly low.

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Martijn J. A. Malessy, Dick Bakker, Ad J. Dekker, J. Gert van Dijk and Ralph T. W. M. Thomeer

Object

Recent progress in the understanding of cerebral plastic changes that occur after an intercostal nerve (ICN)–musculocutaneous nerve (MCN) transfer motivated a study with functional magnetic resonance (fMR) imaging to map reorganization in the primary motor cortex.

Methods

Eleven patients with traumatic root avulsions of the brachial plexus were studied. Nine patients underwent ICN–MCN transfer to restore biceps function and two patients were studied prior to surgery. The biceps muscle recovered well in seven patients who had undergone surgery and remained paralytic in the other two patients. Maps of neural activity within the motor cortex were generated for both arms in each patient by using fMR imaging, and the active pixels were counted. The motor task consisted of biceps muscle contraction. Patients with a paralytic biceps were asked to contract this muscle virtually. The location and intensity of motor activation of the seven surgically treated arms that required good biceps muscle function were compared with those of the four arms with a paralytic biceps and with activity obtained in the contralateral hemisphere regulating the control arms.

Activity could be induced in the seven surgically treated patients whose biceps muscles had regained function and was localized within the primary motor area. In contrast, activity could not be induced in the four patients whose biceps muscles were paralytic. Neither the number of active pixels nor the mean value of their activations differed between the seven arms with good biceps function and control arms. The weighted center of gravity of the distribution of activity also did not appear to differ.

Conclusions

Reactivation of the neural input activity for volitional biceps control after ICN–MCN transfer, as reflected on fMR images, is induced by successful biceps muscle reinnervation. In addition, the restored input activity does not differ from the normal activity regulating biceps contraction and, therefore, has MCN acceptor qualities. After ICN–MCN transfer, cerebral activity cannot reach the biceps muscle following the normal nervous system pathway. The presence of a common input response between corticospinal neurons of the ICN donor and the MCN acceptor seems crucial to obtain a functional result after transfer. It may even be the case that a common input response between donor and acceptor needs to be present in all types of nerve transfer to become functionally effective.