Management of Peripheral Nerve Injuries



Fig. 10.1
(a) A 37-year-old man presented to us 10 weeks after being wounded with shrapnel on the medial aspect of his left ankle injuring the tibial nerve. (b) Surgical exploration showed the presence of a neuroma-in-continuity involving the medial plantar nerve and a neuroma with complete disruption of the lateral plantar nerve. (c) The medial plantar nerve was released from the surrounding neuroma-in-continuity while the neuroma of the lateral plantar nerve was totally excised followed by a direct end-to-end nerve anastomosis. (d, e) Six months after nerve repair, the patient recovered a useful sensation of his sole and a normal function of his toes



Nerve repair is usually performed under loupe or microscope magnification with nylon sutures taken in the epineurium using the simple interrupted suturing technique [1]. While some surgeons perform end-to-end nerve anastomosis randomly, others advocate fascicular repair [1]. It is imperative that nerve repair is performed without tension [1]. Small nerve gaps can be repaired primarily by gently freeing the nerve edges so as to bridge the gap. However, since most war injuries carry a thermal as well as direct component, nerve tissue damage usually extends beyond the initially apparent neuroma, and larger nerve areas have to be excised to arrive at healthy tissue. This results in large gaps that cannot be repaired primarily. Bridging of nerve gaps can be performed using nerve grafts, usually using the sural nerve [1], harvested from the patient’s leg(s) during the same operative procedure (Fig. 10.2). Other nerves that can be utilized as nerve grafts are saphenous nerves, the lateral antebrachial cutaneous nerves, among others [1, 3]. Nerve grafts are reversed to minimize random nerve sprouting and are sutured to the debrided edges of the injured peripheral nerve [5]. In cases of caliber difference between the injured peripheral nerve and the graft, multiple segments or “cables” of the graft can be used to provide adequate number of interposition nerve fascicles [6]. Nerve recovery proceeds at 1 mm/day in healthy young patients and best results of nerve grafting are observed in cases with nerve gap lengths of up to 10 cm and in well-vascularized beds [7]. Despite the frequent use of sensory nerves as grafts to bridge motor nerve gaps due to their expendability, there is evidence to suggest better outcomes in using “like for like” grafts, that is, motor nerve grafts to bridge motor nerve gaps [1, 5].

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Fig. 10.2
(a) A 26-year-old male had a bullet injury to his right wrist totally disrupting the medial nerve with a neuroma and an extensive fibrosis . Surgical exploration was performed 5 months after the initial injury. (b) The neuroma excision led to 6 cm length of median nerve defect. (c) Sural nerve graft using three cables was necessary to bridge the nerve gap. Eight months after nerve grafting, the patient recovered protective sensation without any thumb opposition improvement. Later on, he underwent tendon transfer for opponensplasty

Vascularized nerve grafts have been performed and studied as alternatives to simple nerve grafts, theoretically to allow longer graft lengths and better healing in badly vascularized beds [3]. However, practical advantages of these grafts remain debatable [1]. Vein grafts , as well as tissue-engineered synthetic nerve conduits manufactured from diverse materials ranging from collagen to polyglycolic acid to keratin, have been used to replace autologous nerve grafts. However, all these replacements have been found to be inferior to native nerve grafts and are currently only used for bridging of nerve gaps of up to 3 cm in length [5, 8].

In cases where nerve grafts are not possible due to extensive injury or lack of donor nerves, nerve transfers, or neurotizations, may be performed. Neurotization involves rerouting a functional nerve or fascicle from its original target to a nearby denervated nerve, thereby reestablishing nerve supply to a previously denervated muscle [1, 2]. A commonly performed neurotization is the Oberlin neurotization, whereby a dispensable fascicle of the ulnar nerve (which normally supplies the flexor carpi ulnaris muscle) is sutured to the musculocutaneous nerve to reanimate the biceps muscle (Fig. 10.3). Another example of neurotization is the transfer of the soleus branch of the tibial nerve to the common peroneal nerve in lower extremity peripheral nerve injuries [6]. Neurotizations are frequently performed close to the target muscle; therefore, reanimation of the end organ is quicker than primary repair or grafting of an injured nerve, which would require healing along the entire nerve length. This makes neurotizations very useful when the time elapsed since initial peripheral nerve injury is long and atrophy of the motor end plate is a concern. However, the trade-off is the loss of the original nerve or fascicle that was rerouted or transferred [13, 5].
Nov 17, 2017 | Posted by in MUSCULOSKELETAL MEDICINE | Comments Off on Management of Peripheral Nerve Injuries
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