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Sciatic Nerve Stripping: A Rare Avulsion Injury.

INTRODUCTION

The sciatic nerve is the longest and widest single nerve in the human body extending from the top of the leg to the foot on its posterior aspect. Sciatic nerve injuries are relatively uncommon among all the peripheral nerve injuries.[1] Typical injury to this nerve occurs as a consequence of trauma to the buttock, hip, or posterior thigh. Iatrogenic injury can occur in the setting of injections in the gluteal region[2] or after hip and knee surgery.[3]

Anatomy

The anatomy of the sciatic nerve has been well described in literature.[4-8] It arises from the anterior divisions of L4 through S3 and the posterior divisions of L4 through S2 forming the tibial and peroneal branches, respectively.[7] These nerve fibers coalesce to enter the gluteal region through the greater sciatic foramen below the piriformis muscle coursing inferiorly beneath the biceps femoris muscle in the thigh.[8] Although the tibial and peroneal branches are separate and distinct[1,5] along the entire length of the nerve, these are technically formed as the sciatic nerve bifurcates which is usually in the distal thigh. These innervate the muscles of the back of the thigh, those of the leg and foot besides providing sensation to nearly the entire lower limb.

CASE REPORT

A 55-year-old male presented with a history of fall from height and landing on an iron rod leading to deep penetrating injury to his right buttock. An effort to free himself by pulling against the penetrating rod resulted in transection and complete avulsion of the sciatic nerve.

Inspection revealed a 4-cm-long laceration over the lower half of his right buttock with a thick cord-like structure emanating from the wound site. A detailed examination revealed an avulsion of the entire course of the sciatic nerve along with its terminal branches, namely tibial nerve and common peroneal nerve. The avulsed segment of the tibial nerve and common peroneal nerve measured around 24 and 35 cm, respectively [Figure 1].

Neurological examination revealed hypoesthesia involving lateral aspect of leg (L4 dermatome) with absolute loss of sensations in the foot (L5, S1 dermatome). Motor examination showed loss of dorsiflexion (L4) and plantarflexion (S1) with inability to extend the toes (L5).

The patient was prepared for operative exploration that revealed complete transection and avulsion of the common peroneal nerve at the level of the fibular head and that of tibial nerve in the middle one-third of the calf [Figure 2].

Other than the severe contusion of the avulsed nerve segments, there was no sign of injury to the surrounding structures such as bone, muscles, or blood vessels. It appeared as if the entire length of the nerve had been meticulously avulsed with a tendon stripper. Debridement of the crushed segments resulted in extensive nerve gaps of 18 and 12 cm of tibial and common peroneal nerves, respectively. Both the nerve gaps were reconstructed with multiple cables of nerve grafts from sural nerve and superficial peroneal nerve [Figure 3] from both lower limbs [Figures 4 and 5].

The patient and his family members were informed that data concerning the case would be submitted for publication and proper consent was taken.

RESULTS

In the present case, 1-year follow-up result did not show any significant motor or sensory recovery which is not unexpected. We believe that the reasons for the poor surgical outcome are the proximal nature of the injury, significant contusion to the salvaged nerves, and enormous length of the nerve grafts employed (lengths of 18 and 12 cm). Although the patient was ambulatory and comfortable with the knee-ankle-foot orthosis, he was advised arthrodesis of the ankle joint which he refused.

DISCUSSION

The sciatic nerve is the largest peripheral nerve in terms of length and cross-sectional area and its size presents anatomical challenge for repair. Although the mechanism of injury in this case is in itself peculiar, a "self-inflicted" avulsion of the entire nerve is not reported in literature. Nerves are tough structures that require a significant force to avulse completely. In the present case, the thickest nerve of the body was avulsed completely along its entire anatomical course.

With muscle and sensory targets located at considerable distances from the site of injury and slow nerve regeneration of 2.5 cm/month, successful lower extremity reinnervation requires early repair after injury. While neurotization techniques have revolutionized the surgical treatment of upper extremity injuries (for example, brachial plexus injuries), repair of similar nerve defects in lower limbs often relies on more traditional nerve grafts. In this case, the requirement of enormous quantity of autologous graft material for reconstructing the extensive nerve gap required harvest of sural and superficial peroneal nerves from both the lower limbs [Figure 3].

Functionally, sciatic nerve transection distal to the innervation of the posterior thigh musculature spares knee flexion so that a patient's ability to ambulate is often preserved. Ambulatory function in these cases is contingent on a normally functioning quadriceps and an ankle-foot orthosis. However, in the present case, the proximal avulsion injury resulted in complete denervation of the posterior thigh musculature which could not be reconstructed. Nerve reconstruction was aimed at reinnervation of the leg musculature and possible sensory reinnervation of the sole which otherwise can lead to serious morbidity, including pressure sores.[1,5] In addition, nerve repair can mitigate and/or reduce the incidence of neuroma formation and subsequent development of neuropathic pain.[9]

Postoperatively, the patient was made ambulatory with knee-ankle-foot orthosis and educated at each follow-up visit for protection and care of the insensate part till recovery of protective sensations.

CONCLUSION

Repair of sciatic transection with nerve grafts has yielded variable results in the past. Prognostically, proximal nerve injuries have relatively poor outcomes[10] with children having a better potential for recovery than adults.[11] Some of the largest published studies show variable success rates depending on the level of injury and branches involved.[1,5-7,12,13] For repairs requiring autologous nerve graft, the worst outcomes are seen in the peroneal division at the level of the buttock with favorable outcomes in 21.4-24.3% of cases.[5,7] In contrast, the highest rates of recovery were seen with tibial graft repairs in the mid-thigh, with good outcomes reported in approximately 80% of the cases.[5,7] Additional factors affecting outcome include length of time to surgery (delay >4 months associated with poor outcomes) and length of the nerve defect (length >5 cm has poor outcome).[14]

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

REFERENCES

(1.) Aydin A, Ozkan T, Aydin HU, Topalan M, Erer M, Ozkan S, et al. The results of surgical repair of sciatic nerve injuries. Acta Orthop Traumatol Turc 2010;44:48-53.

(2.) Bigos SJ, Coleman SS. Foot deformities secondary to gluteal injection in infancy. J Pediatr Orthop 1984;4:560-3.

(3.) Simon JP, Van Delm I, Fabry G. Sciatic nerve palsy following hip surgery. Acta Orthop Belg 1993;59:156-62.

(4.) Andersen HL, Andersen SL, Tranum-Jensen J. Injection inside the paraneural sheath of the sciatic nerve: Direct comparison among ultrasound imaging, macroscopic anatomy, and histologic analysis. Reg Anesth Pain Med 2012;37:410-4.

(5.) Gousheh J, Arasteh E, Beikpour H. Therapeutic results of sciatic nerve repair in Iran-Iraq war casualties. Plast Reconstr Surg 2008;121:878-86.

(6.) Gustafson KJ, Grinberg Y, Joseph S, Triolo RJ. Human distal sciatic nerve fascicular anatomy: Implications for ankle control using nerve-cuff electrodes. J Rehabil Res Dev 2012;49:309-21.

(7.) Kim DH, Murovic JA, Tiel R, Kline DG. Management and outcomes in 353 surgically treated sciatic nerve lesions. J Neurosurg 2004;101:8-17.

(8.) Moore KL, Dalley AF: Clinically Oriented Anatomy. 5th ed. Philadelphia: Lippincott Williams and Wilkins; 2006.

(9.) Berrocal YA, Almeida VW, Gupta R, Levi AD. Transplantation of Schwann cells in a collagen tube for the repair of large, segmental peripheral nerve defects in rats. J Neurosurg 2013;119:720-32.

(10.) Cartwright MS, Passmore LV, Yoon JS, Brown ME, Caress JB, Walker FO, et al. Cross-sectional area reference values for nerve ultrasonography. Muscle Nerve 2008;37:566-71.

(11.) Cartwright MS, Mayans DR, Gillson NA, Griffin LP, Walker FO. Nerve cross-sectional area in extremes of age. Muscle Nerve 2013;47:890-3.

(12.) Kline DG, Kim D, Midha R, Harsh C, Tiel R. Management and results of sciatic nerve injuries: A 24-year experience. J Neurosurg 1998;89:13-23.

(13.) Murovic JA. Lower-extremity peripheral nerve injuries: A Louisiana state university health sciences center literature review with comparison of the operative outcomes of 806 Louisiana state university health sciences center sciatic, common peroneal, and tibial nerve lesions. Neurosurgery 2009;65:A18-23.

(14.) Roganovic Z, Pavlicevic G, Petkovic S. Missile-induced complete lesions of the tibial nerve and tibial division of the sciatic nerve: Results of 119 repairs. J Neurosurg 2005;103:622-9.

Suhael Zahur, Kanav Mahajan, Sanjeev Gupta (1)

Department of Plastic Surgery, Government Medical College and Associated Hospitals, (1) Department of Orthopedics, Government Medical College, Jammu, Jammu and Kashmir, India

Address for correspondence: Dr. Suhael Zahur, Aesthetica Clinic Narwal Bypass, Jammu - 180 015, Jammu and Kashmir, India.

E-mail: suhaelz@gmail.com

How to cite this article: Zahur S, Mahajan K, Gupta S. Sciatic nerve stripping: A rare avulsion injury. Turk J Plast Surg 2018;26:122-4.

DOI: 10.4103/tjps.tjps_5_17
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Title Annotation:Case Report
Author:Zahur, Suhael; Mahajan, Kanav; Gupta, Sanjeev
Publication:Turkish Journal of Plastic Surgery
Article Type:Case study
Date:Jul 1, 2018
Words:1614
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