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Brachial Plexus Injuries

Dr. Ashok K. Gupta

Page 3

Topics

Possible Donor Motor Nerve:

  1. Dorsal Root of C-4: Nerve Graft: Nerve to Lat. Dorsi
  2. Accessory Spinal Nerve: Nerve Graft: Nerve to Triceps.
  3. Intercostal nerves T3 – T6: Nerve Graft: Nerve to Biceps Brachii.
  4. Intercostal nerve T7 – T9: Nerve Graft: Banked in Arm for II FFMT.
  5. Contralateral C7 root: Nerve Graft: Cross-Chest banking for FFMT
  6. Phrenic Nerve: Nerve Graft: Banked in Arm for II FFMT.

Depending upon extent of the lesion and residual muscle power, a planned secondary neural reconstitution of the plexus with subsequent Free Functioning muscle transfer in mind is undertaken. Author prefers following combination:

1. Dorsal Root of C-4 to Nerve to Lat. Dorsi: The Dorsal Root (Motor) of C-4 can be identified by following Sensory Cervical branches proximally and using an Intra-operative nerve stimulation to differentiate between the Sensory and the Motor Branches. Microneural co-optation is performed with the Nerve to Latissimus Dorsi Muscle using a Sural Nerve Graft.

2. Accessory Spinal Nerve to Nerve to Triceps: The Accessory spinal nerve provides innervation to Trapezius and the Sternomastoid muscles in neck. The nerve is identified using an intra-operative nerve stimulation and nerve co-aptation is performed with the nerve to Triceps, using a long Sural nerve graft.

3. Intercostal Nerves: The Motor Segments of Intercostal Nerves T3 to T9 are identified using an intra-operative nerve stimulation. Upper three nerves are co-opted directly to the nerve to Biceps Brachii. A long Sural nerve graft is used to lengthen lower four nerves and distal ends are passed subcutaneously to flexor aspect of the elbow and Banked for providing motor axonal outlet for subsequent Free Functional Muscle Transfer.

A functional muscle transfer is designed, when Tinnel signs confirm the growth of axons up to distal end of nerve grafts, which may also be confirmed intra-operatively by frozen section study of the Neuroma, prior to dissection of the muscle. The recipient site is prepared and recipient artery, the vein and the distal end of nerve grafts are identified and tagged for subsequent use. The designated muscle for free transfer is dissected, keeping its neurovascular supply intact. As functional motor power of the transferred muscle is greatly influenced by muscle ischaemia, care is taken to complete all requisite steps at recipient site before actually dividing the vascular pedicle. The transferred muscle is sutured using previously passed transfixation sutures. The muscle should be sutured under sufficient tension so as to cause slight over correction. Neuro-vascular anastomosis is completed promptly with minimum muscle ischaemia time.

For a dynamic re-animation of upper Extremity a functional microneurovascular muscle transfer is the most recent and viable alternative. Tamai was first to report microneurovascular transfer of Gracilis muscle. Usefulness of this procedure was endorsed by reports from Manketlow and O’Brien. The Gracilis muscle has an advantage of predictable and adequate neurovascular pedicle with possibility of incorporating the Skin Island. Latissimus dorsi, Serratus anterior and Rectus abdominis are a few other donor muscles used as free functioning muscle transfer.

Physiotherapy program begins with passive external exercise / splints and a long period of active exercise. Postoperatively, electrical stimulation of the transferred muscle is started after three weeks to maintain physiological tone and nutrition? of the transferred muscle, till it recovers good nerve supply via the cross face grafts. The onset of muscle function / contraction varied from 2 – 4 months following transplantation. A full range of muscle contraction was obtained within 6 – 9 months of transplantation. Grip strength gradually increased over a period of 2 years and then slowly increased for an additional year or more. Most workers have reported good results with free functioning muscle transfer, re-innervated either by muscular neurotization, nerve implantation or nerve suture. However, final functional results were dependent on spontaneous vascularization and sufficient re-innervation.

Neuro – muscular neurotization implies direct implantation of Motor Nerve in to the denervated muscle. This method developed by Stiendler, Atiken, Sorble and Porter is being used by Narakas and Hentz, when nerves such as Supra-scapular, Axillary, Radial or Median are avulsed from their muscles.

Histologic Findings:

Nerve implantation gap resulted in less complete re-innervation. Numerous gaps of small atrophic fibers were absent among obviously re-innervated fiber. However the gross distinction between a central “red” zone containing more NADH reactive fibers, and a peripheral white zone was still possible. In a NADH stained sections of the central zone, higher and uniform intensity of staining was characteristic. In the peripheral white zone, large profiles of hypertrophic muscle fiber were typical. In more than half the muscle fibers, the myonuclei were seen in the central position.

Muscular neurotization has taken place in all seven cases but this kind of re-innervation was less successful than the other two. Single bundles of re-innervated type grouped muscle fibers were found. In addition to these normal looking fibers, small atrophic as well as hypertrophic fibers were absent. Central position of the myonuclei was similar to the other gap. The volume of the operated muscles of this gap was usually reduced to approximately half that of the control muscles.

Nerve Banking concept popularized by Terzis, implies carrying of a distant Motor Axonal Output to an Accessible site, that is (the shoulder or proximal arm) with or without the help of a Interposition Nerve Graft, for subsequent free functioning muscle transfer. In neglected or delayed cases of Brachial Plexus Injury wherein, the time since injury is so long (>1-2 years) that it would preclude successful neurotization or re-innervation of previously denervated muscles. Usually the spinal accessory or intercostal nerves are directed to the vicinity of shoulder or Proximal Arm with the help of a Interposition Nerve Graft. The distal end of graft is left un-sutured and is allowed time for axonal regeneration, following which a healthy muscle like the Latissimus dorsi, Gracillis are transferred to the Shoulder and Arm by microvascular free tissue transfer. The nerve of the transferred muscle is then joined to the previously placed nerve graft.

Friedman et. al. reported 50% success following a co-aptation between the transposed intercostal nerves and Free Vascularized Gracillis Muscle, transferred to the position of Biceps.Akasaka et. al. have reported Free Functioning Muscle Transfer combined with Inter-costal Nerve for reconstruction of Elbow Flexion and Wrist Extension. Chuang et.al. used contra lateral C7 as donor motor nerve with a cross-chest nerve graft , which was subsequently co-opted to nerve in free muscle transplantations. Doi et. al. reported double Free Functioning Muscle Transfer to restore pre-hension following complete avulsion.


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