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Neurotomesis: Donald Serafin M.D.
Surgery of the Peripheral Nerve Web Site: Duke University Medical Center
- age of the patient is the single most critical factor in sensory recovery after nerve repair, but results are adversely affected by associated
injuries to muscle, arteries, tendons, and bone;
- results of nerve repair begin to decline after second decade (75% good results in children vs 50% good results in adults);
- results of nerve repair may be poor after the sixth decade;
- in the study by Bolitho DG, et al (1999), 5 children with proximal unlar nerve injuries regained satisfactory hand intrinsic
strength (where as the authors note that this type of recovery is not generally seen in adults);
- Primary epineural repair of the ulnar nerve in children.
- Functional Outcome Thirty Years After Median and Ulnar Nerve Repair in Childhood and Adolescence
- mechanism of injury:
- low velocity gun shot wounds are often associated w/ neuropraxic injuries, which can heal with time;
- in this case, consider EMG at 3 months inorder to determine whether nerve regeneration is occuring;
- high velocity gun shot wounds are more likely to be associated w/ diffuse severe inovolvement and have a poor prognosis w/ surgical repair;
- combination injuries:
- when there is a combination of soft tissue loss, fracture, and nerve injury, there will be a poor prognosis for surgical
nerve repair due to the poor wound environment, risk of infection, and risk of scarring;
- primary vs secondary repair:
- note: when secondary nerve repair is chosen, the surgeon should determine the proper orientation of each nerve end at the time of initial debridement,
and each nerve end should be marked with an epineural suture, which facilitates orientation of the ends at the time of definative repair;
- note: the longitudinal epineural vessels which are used to orient the nerve may not be as prominent w/ secondary surgery;
- tendon transfers: (in the upper extremity)
- it is advisable to proceed w/ full component of tendon transfer early when there is a questionalble or a poor prognosis for nerve repair;
- if there is a nerve gap > 4 cm or if there is a large wound or extensive scarring or skin loss over nerve,
consider ignoring the nerve and proceeding directly to tendon transfer;
- nerve transfer:
- in the report by Özkan T, et al., prospective study was conducted to evaluate patient outcomes following sensory nerve transfer;
- 20 patients with irreparable ulnar or median nerve lesions underwent the procedure;
- 18 of 20 patients attended a sensory re-education program after surgery;
- 2-point discrimination of less than 10 mm was achieved in 15 of 25 hands;
- 18 of 20 patients reported that the function of their hands improved after the procedure;
- good or excellent results were associated with immediate transfer of the nerve, young age, and patients' attendance to the sensory re-education program after surgery;
- ref: Restoration of sensibility in irreparable ulnar and median nerve lesions with use of sensory nerve transfer: long-term follow-up of 20 cases.
- nerve conduits:
- may be indicated when tension free repair is not possible;
- may only allow 2 cm of nerve regeneration;
- Repair Based on Level of Injury:
- nerve repair in the hand: (see: exam of the hand)
- more proximal lacerations have worse outcomes than distal lacerations;
- at the wrist level, one half of patients will have good result;
- exam findings for nerve injury:
- loss of two point discrimination;
- dryness over the affected dermatomes (loss of sweat gland innervation)
- digital nerves:
- digital nerves may contain one to three fasicles;
- best managed w/ epineural nerve repair
- use 9-0 or 10-0 prolene;
- patients may expect functional / protective sensation, but in the majority of patients, normal sensation will not be obtained;
- generally nerve repair is not indicated distal to the DIP;
- median and ulnar nerves at the wrist:
- low median lesions (median nerve injuries at the wrist)
- low ulnar lesions
- in these injuries, wrist flexion signficantly reduces tension at the nerve repair site;
- elbow flexion and nerve transposition will have no effect on tension at the repair site;
- group fasicular nerve repair may be indicated for nerve lacerations at the wrist level;
- ulnar nerve lacertions at the elbow:
- tension at nerve repair site may be reduced by both nerve transposition and elbow flexion, but magnitude of this effect remains unclear;
- The role of ulnar nerve transposition in ulnar nerve repair: a cadaver study.
- Nerve Repair Techniques:
- note that whatever repair technique is used, the repair should be strong to withstand the need for early ROM should it be necessary (as in concomitant tendon injury);
- epineural nerve repair:
- involves repair of the epineural tissue - the loose connective tissue which surrounds the fascicles;
- group fasicular nerve repair:
- involves repair of the internal epineural tissue which surrounds the group fascicles;
- disadvantages include increased need for nerve manipulation inorder to align fasicles and the possibility of anastomosing incorrect fasicles (which
will lead to a poor result);
- management of tension at nerve site repair:
- nerve grafts:
- indicated for nerve defects more than 1 cm (or in any case where the nerve would be repaired under tension);
- sural nerve graft;
- note that the patient must be in the lateral position for nerve harvest, which may interfere with positioning of the injured extremity;
- medial antebrachial cutaneous nerve
- lateral antebrachial cutaneous nerve
- The nerve gap dilemma: a comparison of nerves repaired end to end under tension with nerve grafts in a primate model.
- Use of the anterior branch of the medial antebrachial cutaneous nerve as a graft for the repair of defects of the digital nerve.
- Digital nerve-grafting for traumatic defects. Use of the lateral antebrachial cutaneous nerve.
- Post Operative Care:
- as noted by Abrams, et al (1998), the rat sciatic nerve achieved 64% of its ultimate strength in the first week postop;
- the authors noted that it was difficult to extrapolate this information to human nerves;
- after repair, an advancing Tinel's sign should be elicited after adequate time has elapsed for the regenerating axons to bridge repair site;
- length of the latent period is related to the technical success of repair, usually equally one month;
- then the nerve advances 1mm each day;
- Biomechanics and Histology of Intact and Repaired Digital Nerves: An In Vitro Study.
- Tensile properties of the neurorrhaphy site in the rat sciatic nerve.
Variations in digital nerve anatomy.
Use of the anterior branch of the medial antebrachial cutaneous nerve as a graft for the repair of defects of the digital nerve.
Digital nerve-grafting for traumatic defects. Use of the lateral antebrachial cutaneous nerve.
Nerve regeneration in a bony bed: vascularized versus nonvascularized nerve grafts.
The nerve gap dilemma: a comparison of nerves repaired end to end under tension with nerve grafts in a primate model.
Primary nerve repair in the upper limb. Our preferred methods: theory and practical applications.
Long-term follow-up evaluation of cold sensitivity following nerve injury.
Tensile properties of the neurorrhaphy site in the rat sciatic nerve.
Management of Peripheral Nerve Defects: External Fixator-Assisted Primary Neurorrhaphy.
Methylene blue staining for nerve-sparing operative procedures: an animal model.