Hand Surgery Source

MEDIAN NERVE LACERATION

Introduction

The complete transection of the median nerve continues to be a challenging problem for hand surgeons and their patients. Despite advances in microsurgical nerve repair, repairs often leave patients with functional deficits, especially in adults and particularly in terms of fine sensory function.1,2,3

Pathophysiology

  • When a nerve is transected, the distal segment of the nerve undergoes Wallerian degeneration.
    • Distal axons degenerate secondary to calcium-activated calpain enzymes;6,7 degenerating myelin is phagocytized by Schwann cells and macrophages.
      • In the proximal stump, degeneration also occurs in a proximal direction for a distance of ≥1 nodes of Ranvier.
      • In the distal segment, Schwann cells proliferate forming the bands of Bunger.
    • In the proximal segment of the axon cone develops and grows distally at a rate of 1-2mm/day (1 inch/mo) after the cut ends of the nerve have been approximated and realigned by microsurgical repair.
  • Median nerve lacerations are usually classified as complete or partial
    • Partial: some intact tissue connections between the nerve endings
    • Complete: no physical connection between the nerve endings (neurotomesis)
  • Axonotomesis: nerve is subjected to severe crush, stretch, or blast injury; axon can be severed with distal degeneration, while the Schwann cell basil lamina remains intact
  • Neuropraxia: nerve is stretched and stops conducting impulses while the neural anatomy remains intact; There is no Wallerian degeneration after this type of stretch injury, and they usually recover without surgical intervention6

Related Anatomy

  • The median nerve is composed of nerve fibers and axons that are covered by connective tissue called endoneurium.
  • The axon has a cell membrane (axolemma) surrounding a tube of neural cytoplasm (axoplasm).6
  • Axons are grouped in fascicles that are surrounded by the perineurium.5
    • Perineurium provides a diffusion and conduction barrier between the fascicles.6
  • In the median nerve, groups of fascicles are arranged in fascicular groups, defined by the connective tissue called the internal epineurium.
  • In the distal part of the nerve, there are few connections between the fascicular groups; thus, the internal epineurium provides a surgical plane that can be dissected with microsurgical techniques.5
  • These fascicular groups together compose the median nerve; external surface of the median nerve is the external epineurium.
  • When the median nerve is cut, the nerve ends separate producing a functional gap due to fascicular group inherent elasticity.
  • There is no loss of nerve tissue, ie, no true defect; therefore, these ends can be repaired without excessive tension even if a few millimeters of neuroma are resected.5
  • If there is a long delay between laceration and nerve repair, the functional elastic gap may become more of a true defect because of scarring.
  • Most surgeons recommend mobilizing the nerve and gentle flexion of adjacent joints and end-to-end repair; if the true defect is 3-4 cm, nerve grafting would be indicated.12,13

Incidence

  • Peripheral nerve injury remains a common injury in civilian life.
  • In one report, an estimated 20 million Americans suffer peripheral nerve injuries annually.8
  • In 2006, there were 2700 admissions for median nerve lacerations; nearly 80% were males with an age range of 18-44 years.9
  • Another report showed that 11% of wartime nerve injuries were lacerations of the median nerve.10

Differential Diagnosis

  • Complete nerve laceration
  • Partial nerve laceration
  • Neuropraxia (stretch injury)
  • Neuroma-in-continuity
ICD-10 Codes

MEDIAN NERVE LACERATION

Diagnostic Guide Name

MEDIAN NERVE LACERATION

ICD 10 Diagnosis, Single Code, Left Code, Right Code and Bilateral Code

DIAGNOSIS SINGLE CODE ONLY LEFT RIGHT BILATERAL (If Available)
MEDIAN NERVE LACERATION        
- UPPER ARM LEVEL   S44.12X_ S44.11_  
- FOREARM LEVEL   S54.12X_ S54.11X_  
- AT WRIST AND HAND LEVEL   S64.12X_ S64.11X_  

Instructions (ICD 10 CM 2020, U.S. Version)

CODE ALSO ANY ASSOCIATED OPEN WOUND (S41.-), (S51.-), (S61.-)

 

THE APPROPRIATE SEVENTH CHARACTER IS TO BE ADDED TO EACH CODE FROM CATEGORY S68
A - Initial Encounter
D - Subsequent Routine Healing
S - Sequela

ICD-10 Reference

Reproduced from the International statistical classification of diseases and related health problems, 10th revision, Fifth edition, 2016. Geneva, World Health Organization, 2016 https://apps.who.int/iris/handle/10665/246208

Clinical Presentation Photos and Related Diagrams
Median Nerve Lacerations
  • Typical volar wrist laceration associated with a median nerve laceration.
    Typical volar wrist laceration associated with a median nerve laceration.
  • Laceration Median Nerve (MN) in an anatomic specimen. Palmaris longus (PL) also visible.
    Laceration Median Nerve (MN) in an anatomic specimen. Palmaris longus (PL) also visible.
  • Laceration Median Nerve (1) with anhydrotic skin (2).
    Laceration Median Nerve (1) with anhydrotic skin (2).
  • Chronic laceration Median Nerve (1) with thenar atrophy and flattened palmar arch (2).
    Chronic laceration Median Nerve (1) with thenar atrophy and flattened palmar arch (2).
  • Laceration Median Nerve (arrow) undergoing microsurgical repair.
    Laceration Median Nerve (arrow) undergoing microsurgical repair.
  • Median Nerve (MN) encased in radial fracture callus (arrow).
    Median Nerve (MN) encased in radial fracture callus (arrow).
  • Median Nerve partial laceration (arrow).
    Median Nerve partial laceration (arrow).
Basic Science Photos and Related Diagrams
Median Nerve Laceration Basic Science
  • Median Nerve with axons enclosed in endoneurium (1); Fascicle enclosed in perineurium (2); Fascicular groups enclosed in connective tissue called internal epineurium (3); Internal epineurium (4); External epineurium (5); Epineural blood vessels (6).
    Median Nerve with axons enclosed in endoneurium (1); Fascicle enclosed in perineurium (2); Fascicular groups enclosed in connective tissue called internal epineurium (3); Internal epineurium (4); External epineurium (5); Epineural blood vessels (6).
Pathoanatomy Photos and Related Diagrams
Median Nerve Laceration Pathoanatomy and Clinical Tools
  • Median Nerve (MN) with palmaris longs (PL) resting on its palmar surface.
    Median Nerve (MN) with palmaris longs (PL) resting on its palmar surface.
  • Palmar cutaneous branch (arrow) of the Median Nerve (MN) with underlying tendons.
    Palmar cutaneous branch (arrow) of the Median Nerve (MN) with underlying tendons.
  • EMG/NCV investigations may help define location and magnitude of closed nerve injuries.
    EMG/NCV investigations may help define location and magnitude of closed nerve injuries.
  • Intra-operative NCV investigations can help defined conducting and non-conducting nerve fascicles.
    Intra-operative NCV investigations can help defined conducting and non-conducting nerve fascicles.
  • Lacerations of the Median Nerve will need microsurgical repair.
    Lacerations of the Median Nerve will need microsurgical repair.
  • Microsurgical instruments for nerve repair.
    Microsurgical instruments for nerve repair.
  • Microsutures for microsurgical repair.
    Microsutures for microsurgical repair.
  • Microsurgical lab for practicing nerve repair techniques (see insert).
    Microsurgical lab for practicing nerve repair techniques (see insert).
Symptoms
History of trauma with a laceration in the area of the median nerve
Sensory loss
Wound pain and paresthesias
Loss of normal motor function
Typical History

A 27 year old male was drinking heavily and fell against a glass door which broke.  The broken glass cut the palmar surface of his left wrist.  It was bleeding severely.  A friend applied a pressure dressing and took the patient to the emergency room. The examination of the hand revealed a loss of sensation in the median nerve distribution.  Wound showed a relatively clean cut. The wound was anesthetized with 1% local. Wound exploration showed a cut palmaris longus tendon and a cut median nerve.  The wound was irrigated, debrided, the skin sutured and a dressing and splint applied.  The patient saw a hand surgeon who did a microsurgical median nerve repair in the local ambulatory surgery center the following week.

Positive Tests, Exams or Signs
Work-up Options
Treatment Options
Treatment Goals
  • Identify the presence of a complete median nerve laceration, a partial median nerve laceration, or a median nerve neuropraxia.
  • Repair the complete or partial nerve laceration.
  • Carefully follow the patient with a median nerve stretch injury; some patients with neuropraxia will require neurolysis.
  • Improve function of injured upper extremity with a median nerve laceration.
Conservative
  • Nonoperative treatment of median nerve complete or partial lacerations is appropriate when the patient’s associated injuries or medical comorbidities prevent anesthesia and a lengthy microsurgical repair.
  • Isolated median nerve complete and partial lacerations should be repaired early, but repair is not an emergency.
  • Irrigation, debridement, and closure of the skin laceration with a scheduled operative nerve repair 1-3 few weeks is reasonable.
  • Neuropraxia of the median nerve secondary to a stretch injury is rare, but a stretch injury could be watched for signs of spontaneous recovery.
  • An exception to the watch-and-wait plan for a median nerve neuropraxia includes acute carpal tunnel syndrome associated with a distal radius fracture, which does not resolve soon after fracture reduction and splinting.
  • Another exception is the patient with severe compartment syndrome type median nerve pain that continues or worsens with fracture reduction.
    • This patient with severe nerve pain may have the median nerve caught in the fracture (photo).
Operative

Complete Nerve Lacerations

  • Complete median nerve lacerations in civilian practice are usually seen acutely and are caused by sharp lacerations from broken glass, knives, saws, or vehicular accidents.
  • Complete nerve lacerations should be repaired with microsurgical procedures.
  • Choices for microsurgical repair include:
    1. Epineural repair
    2. Group fascicular repair
    3. Nerve repair with nerve grafts
    4. Nerve repair with nerve conduit
    5. Nerve transfers

Partial Nerve lacerations

  • Partial nerve lacerations can be repaired by dissecting the internal epineurium and isolating the transected fascicular groups, gently looping the intact fascicular groups and then repairing the cut fascicular groups by suturing the internal epineurial sheaths.
  • If there is a significant true defect, for example after a bullet wound, then repairing the cut fascicular groups with nerve grafts between the cut fascicular groups is indicated.
  • Neurolysis of the median nerve for a neuropraxia is uncommon.1,6

Nerve Transfers17

  • Nerve transfer for brachial plexus reconstruction are well defined in the literature; however, their usefulness for reconstructing median nerve lacerations is still evolving.1 However, nerve transfer(s) have been gaining in popularity as an alternative to tendon transfers/nerve grafting for patients with severe proximal nerve injuries, but the field is still evolving with new techniques being described as microsurgical techniques improve and more patients experience good outcomes.
  • Proposed Advantages of Nerve Transfer

-       Able to also restore sensory function

-       Multiple muscle groups can be reinnervated with a single nerve transfer

-       Muscle origin/insertions are not disrupted

  • Principles of Nerve Transfer

-       Ideally pick a donor nerve near the motor endplates of the target muscle to minimize time to innervation.  A shorter distance means shorter time for reinnervation

-       Use expendable or redundant nerve fibers

-       Use donors that have a large number of axons

-       Use donors that already innervate synergistic muscles with the target muscle (helps facilitate re-education)

-       Using donors that match the target is ideal, i.e. motor donors for motor targets, sensory donors for sensory targets

-       Re-innervation after 12-18 months may be impossible, as prolonged denervation will cause muscle cell death and fibrosis.

  • Nerve transfers for Median Nerve Palsy

-       Goals: Restore forearm pronation, thumb opposition, finger flexion, median sensation

-       Pronation – 1 or 2 branches of FDS are transferred to non-functioning branches to pronator teres.  Alternative donors include the brachialis branch of the musculocutaneous nerve or the brachioradialis branch of the radial nerve

-       Finger flexion – medial antebrachial cutaneous or medial brachial cutaneous can be transferred to the AIN to restore finger flexion

-       Thumb Opposition – branch from AIN to the pronator quadratus can be transferred to the median nerve

Treatment Photos and Diagrams
Median Nerve Repair Diagrams
  • Median Nerve Laceration being repaired with microsurgical repair of the epineurium.
    Median Nerve Laceration being repaired with microsurgical repair of the epineurium.
  • Group fascicular microsurgical repair of median nerve laceration. Internal epineurium sutured.
    Group fascicular microsurgical repair of median nerve laceration. Internal epineurium sutured.
  • Microsurgical repair of digital nerve laceration using a nerve graft to fill a true neural defect.
    Microsurgical repair of digital nerve laceration using a nerve graft to fill a true neural defect.
  • Median nerve laceration with true defect repaired with sural nerve grafts.
    Median nerve laceration with true defect repaired with sural nerve grafts.
  • Median nerve with a partial laceration. Note the cut fascicular groups (arrows). The first repair step is to dissect the intact fascicular groups away from the cut groups (dotted line).
    Median nerve with a partial laceration. Note the cut fascicular groups (arrows). The first repair step is to dissect the intact fascicular groups away from the cut groups (dotted line).
  • After dissecting the intact fascicular groups free, a 8-0 suture is used to temporarily control the elastic tension while cut groups are repaired.
    After dissecting the intact fascicular groups free, a 8-0 suture is used to temporarily control the elastic tension while cut groups are repaired.
  • With small partial lacerations, a simple repair of the epineurium is appropriate.
    With small partial lacerations, a simple repair of the epineurium is appropriate.
Median Nerve Complete Laceration Microsurgical Repair
  • Median Nerve (MN) Laceration with cut palmaris longs (PL).
    Median Nerve (MN) Laceration with cut palmaris longs (PL).
  • Median Nerve (MN) Laceration with cut palmaris longs (PL). Exposure extended. Note the elastic gap between the nerve endings.
    Median Nerve (MN) Laceration with cut palmaris longs (PL). Exposure extended. Note the elastic gap between the nerve endings.
  • Median Nerve (MN) Laceration - note the true defect when a segment of nerve is removed in this anatomic specimen.
    Median Nerve (MN) Laceration - note the true defect when a segment of nerve is removed in this anatomic specimen.
  • Median Nerve (MN) Laceration - with ragged edges of nerve endings removed with serrated micro-scissors or nerve cutting tool (insert).
    Median Nerve (MN) Laceration - with ragged edges of nerve endings removed with serrated micro-scissors or nerve cutting tool (insert).
  • Median Nerve (MN) Laceration ready for repair with minimal gap.
    Median Nerve (MN) Laceration ready for repair with minimal gap.
  • Median Nerve (MN) Laceration begun. One 8-0 nylon suture in place which easily controls the tension between the nerve endings.
    Median Nerve (MN) Laceration begun. One 8-0 nylon suture in place which easily controls the tension between the nerve endings.
  • Median Nerve (MN) Laceration. Second suture being placed.
    Median Nerve (MN) Laceration. Second suture being placed.
  • Median Nerve (MN) Laceration. Palmar median nerve micro-repair completed.
    Median Nerve (MN) Laceration. Palmar median nerve micro-repair completed.
Median Nerve Partial Laceration Microsurgical Repair
  • Median nerve in distal third of forearm with a 50% partial laceration from a glass cut.
    Median nerve in distal third of forearm with a 50% partial laceration from a glass cut.
  • Partial median nerve laceration. The cut fascicular groups are dissected in the internal epineural plane (arrow) from the intact fascicular groups.
    Partial median nerve laceration. The cut fascicular groups are dissected in the internal epineural plane (arrow) from the intact fascicular groups.
  • The cut fascicular groups have been separated from the intact groups. Note the minimal force needed to approximate the cut ends (insert).
    The cut fascicular groups have been separated from the intact groups. Note the minimal force needed to approximate the cut ends (insert).
  • Tension temporarily controlled with a single 8-0 suture. Cut ends trimmed with nerve cutting tool (insert).
    Tension temporarily controlled with a single 8-0 suture. Cut ends trimmed with nerve cutting tool (insert).
  • Fascicular group repair complete. Suture holding the loop removed. Final result (insert).
    Fascicular group repair complete. Suture holding the loop removed. Final result (insert).
CPT Codes for Treatment Options

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Common Procedure Name
Median nerve repair
CPT Description
Suture 1 nerve; hand or foot, median motor thenar
CPT Code Number
64835
Common Procedure Name
Opponensplasty
CPT Description
Opponensplasty; superficialis tendon transfer type, each tendon
CPT Code Number
26490
Common Procedure Name
Tendon transfer
CPT Description
Tendon transplant or transfer flexor/extensor single each tendon

CPT Code Number
25310
Common Procedure Name
Extensor tendon transfer
CPT Description
Tendon transfer or transplant, CM area or dorsum of hand single w/o free graft

CPT Code Number
26480
CPT Code References

The American Medical Association (AMA) and Hand Surgery Resource, LLC have entered into a royalty free agreement which allows Hand Surgery Resource to provide our users with 75 commonly used hand surgery related CPT Codes for educational promises. For procedures associated with this Diagnostic Guide the CPT Codes are provided above. Reference materials for these codes is provided below. If the CPT Codes for the for the procedures associated with this Diagnostic Guide are not listed, then Hand Surgery Resource recommends using the references below to identify the proper CPT Codes.

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 CPT 2021 Professional Edition: Spiralbound

Complications
  • Loss of sensation
  • Loss of motor function
  • Persistent pain and/or paresthesias
  • Neuroma-in-continuity
  • Infection
  • Carpal tunnel syndrome
  • Complex regional pain syndrome
Outcomes
  • Permanent deficits after nerve repair remain a problem, especially for adults.1
  • Chemnitz, et al3reported function of patients younger than 12 years had an 87% functional return while older patients’ functional recovery averaged 67%. Functional assessment was done with the DASH score and the Rosen score.
  • Since World War II, the results of nerve repair also have been a grade system designed by the British Medical Research Council.6,14,15

 

THE MEDICAL RESEARCH COUNCIL SYSTEM6,14,15
 
Motor Recovery
M0 No contraction
M1 Return of perceptible contraction in the proximal muscles
M2 Return of perceptible contraction in both the proximal muscles and distal muscles
M3 Return of perceptible contraction in both the proximal muscles and distal muscles of such a degree that all important muscles are sufficiently powerful to act against resistance
M4 Return of function as in stage 3 with the addition that all synergic and independent movements are possible
M5 Complete recovery
Sensory Recovery
S0 Absence of sensibility in the autonomous area
S1 Recovery of deep cutaneous pain sensibility within the autonomous area of the nerve
S2 Return of some degree of cutaneous pain and tactile sensibility within the autonomous area
S3 Return of some degree of superficial cutaneous pain and tactile sensibility within the autonomous area with disappearance of any previous overreaction within the autonomous area
S3+ Return of some sensibility as in stage 3 with the addition that there some recovery of two point discrimination within the autonomous area
S4 Complete recovery
  • Other factors that affect the outcome of median nerve repair include the age of patient (young patients do better); the level of the laceration (distal lacerations do better); the type of nerve (pure motor or pure sensory nerves do better); the delay between injury and repair matters (earlier repairs do better); and the cause of the median nerve laceration (sharp clean cuts do better).1,6  
Video
Microsurgical Nerve Repair
Key Educational Points
  • Dry skin (anhydrosis) in the distribution of a potentially cut nerve suggests a complete or partial laceration.
  • Pre-operative EMG/NCV electrodiagnostic testing can help define the level of the nerve injury and the completeness of the nerve injury (ie, neuropraxia vs axonotomesis).1,6  Electrodiagnostic testing may also show signs of recovery before recovery can be identified by physical examination.
  • MRI can help identify and define nerve tumors, nerve stretch, injuries and neuromas-in-continuity.1
  • The Marin-Gruber connection anastomosis occurs in approximately 17% of the population.  This connection carries motor fibers from the median to the part of the ulnar nerve which supplies the intrinsic muscles.16
References
  1. Pederson, WC.  Median nerve injury and repair.  J Hand Surg Am 2014; 39:1216-1222.
  2. Galanakos SB, Zoubous AB, Ignatiadis I, Papakostas I, Gerostathopoulos NE, Soucacos PN.  Repair of complete nerve lacerations at the forearm: an outcome study using Rosen-Lundborg protocol.  Microsurgery 2011; 31(4):253-62.
  3. Chemnitz A, Bjorkman A, Dahlin LB, Rosen B.  Functional outcome thirty years after median and ulnar nerve repair in childhood and adolescence.  J Bone Joint Surg Am 2013; 95:329-337.
  4. Steinberg DR, Koman LA.  Factors affecting the results of peripheral nerve repair.  In: Operative Nerve Repair and Reconstruction, Gelberman RH (ed), Philadelphia, JB Lippincott Co, 1991:349-364.
  5. Hurst.  Hurst, L.C., Dowd, A., Sampson, S.P., and Badalamente, M.A.: Partial Lacerations of the Median and Ulnar Nerves.  J. Hand Surg 1991 16A:207-10.
  6. Birch R.  Nerve repair. In: Green’s Operative Hand Surgery, Wolfe SW, Hotchkiss RN, Pederson WC, Kozin SH (eds), Philadelphia, Elsevier Churchill Livingstone, 2011:1035-1092
  7. Fernandez L, Komatsu, DE, Gurevich, M, Hurst, LC.  Emerging strategies on adjuvant therapies for nerve recovery.  J Hand Surg Am 2018:43(4):368-373.
  8. Taylor CA, Braza, D, Rice JB, Dillingham T.  The incidence of peripheral nerve injury in extremity trauma. Am J Phys Med Rehabil 2008;87(5):381-385.
  9. Lad SP, Nathan JK, Schuberg RD, Boakye M.  Trends in median, ulnar, radial, and brachioplexus nerve injuries in the United States.  Neurosurgery 2010:66(5):953-960.
  10. Birch R, Misra P, Stewart MP, et al.  Nerve injuries sustained during warfare: part II: Oucomes. J Bone Joint Surg Br. 2012;94(4):529-535.
  11. Edshage S.  In: Jewett D, McCarroll H, eds.  Nerve repair and regeneration: Its clinical and experimental basis.  St. Louis: CV Mosby, 1980:279-283.
  12. Millesi H.  The nerve gap: theory and clinical practice. Hand Clinics 1986;2:651-664.
  13. Terzis J, Faibisoff B, Williams H. The nerve gap: suture under tension vs. graft. Plastic Reconstr Surg 1975; 56:166-170.
  14. Seddon HJ. Surgical disorders of the peripheral nerves, ed 7. Edinburgh, Churchill-Livingstone, 1975;276-280.
  15. Seddon HJ (ed): Peripheral Nerve Injuries, Medical Research Council Special Report Series No. 282, London, Her Majesty’s Stationery Office, 1954.
  16. Leibovic SJ, Hastings H. Martin-Gruber revisited. J Hand Surg. 1992; 17A: 47-53.
  17. Weber RV, Mackinnon SE. Nerve transfers in the upper extremity. J Hand Surg Am. 2004; 4(3): 200-213.