x
x

SUPERFICIAL DORSAL RADIAL SENSORY NERVE LACERATION

Introduction

The superficial dorsal radial sensory (SDRS) nerve is more susceptible to injury than any other nerve in the wrist because of its subcutaneous position on the radial-dorsal aspect of the forearm. The complete transection of the SDRS nerve continues to be a challenging problem for hand surgeons and their patients. Despite advances in microsurgical nerve repair, repairs often leave patients with sensory deficits and pain neuromas, especially in adults.1-4
 

Pathophysiology

  • When a nerve is transected, the distal segment of the nerve undergoes Wallerian degeneration.  Distal axons degenerate secondary to calcium-activated calpain enzymes.5,6 The 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 after nerve transection.  In the proximal segment, 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.
  • SDRS nerve lacerations are usually classified as complete or partial.
    • Partial: some intact nerve 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 intervention.6
  • The SDRS nerve has been found to be more susceptible to traumatic injury than any other sensory nerve in the wrist, which is primarily due to its subcutaneous position on the radial-dorsal aspect of the forearm.4 Possible causes of injury include fracture-related trauma, lacerations from stab or gunshot wounds, iatrogenic injury, and contusions. Iatrogenic injury can occur with distal radius repair during insertion of K-wires with release of the first extensor compartment, or with other surgical procedures in the region.7,8

Related Anatomy

  • The radial nerve is composed of nerve fibers and axons covered by connective tissue called epineurium. The radial nerve travels in the posterior compartment of the arm, deep to the long head and enveloped in the medial and lateral heads of the triceps muscle. It traverses the spiral groove of the humerus, and passes anteriorly through the lateral intermuscular septum in the supracondylar region.9  The SDRS is composed of:
  • The axon has a cell membrane (axolemma) surrounding a tube of neural cytoplasm (axoplasm).6  Axons are encased by the endoneurium.
  • Axons are grouped in fascicles that are surrounded by the perineurium.11 Perineurium provides a diffusion and conduction barrier between the fascicles.6
  • In the SDRS nerve, groups of fascicles are arranged in fascicular groups, defined by the connective tissue called the internal epineurium.
  • These fascicular groups together compose the SDRS nerve; external surface of the SDRS nerve is the external epineurium.
  • When the SDRS 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 usually be repaired without excessive tension even if a few millimeters of neuroma are resected within the first 1-4 weeks after injury.11
  • 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 performing an end-to-end repair.  However, if the true defect is 3-4 cm, nerve grafting would be indicated.12,13
  • The SDRS nerve is one of the radial nerve branches in the forearm. After the radial nerve enters the forearm, it divides into deep and superficial branches. The superficial branch, once it leaves the forearm’s flexor compartment and moves to its dorsal region, gives off two or three branches.2 The SDRS branches go to the dorsal region of the hand and the dorsal region of the thumb, index, long radial dorsal ring finger.10,21 The SDRS nerve is a branch of the radial nerve that travels through the proximal dorsal forearm underneath the brachioradialis and enters the subcutaneous tissues in the interval between the brachioradialis and the extensor carpi radialis longus approximately 9 cm proximal to the tip of the radial styloid.  The SDRS nerve branches into 2-3 branches about 5 cm proximal to the radial styloid.21

Incidence

  • Peripheral nerve injury remains a common injury in civilian life.
  • In one report, an estimated 20 million Americans suffer peripheral nerve injuries annually.14
  • In 2006, there were 3,300 admissions for radial nerve lacerations; 70.8% of these patients were male, and 58.7% were in the 18-44 age group.15
  • Another report showed that 9% of wartime nerve injuries were lacerations of the radial nerve.16

Differential Diagnosis

  • Complete nerve laceration
  • Partial nerve laceration
  • Neuropraxia (stretch injury)
  • Neuroma-in-continuity
Clinical Presentation Photos and Related Diagrams
Dorsal Radial Sensory Nerve
  • Left dorsal radial sensory nerve (arrow) dissected during exposure of first extensor compartment.
    Left dorsal radial sensory nerve (arrow) dissected during exposure of first extensor compartment.
  • Left dorsal radial sensory nerve laceration at "X" (1); Radial styloid outlined (2); cross marked area where patient is experiencing numbness and paresthesias (3).
    Left dorsal radial sensory nerve laceration at "X" (1); Radial styloid outlined (2); cross marked area where patient is experiencing numbness and paresthesias (3).
  • Epineural repair option for dorsal radial sensory nerve laceration
    Epineural repair option for dorsal radial sensory nerve laceration
  • Nerve graft repair option for dorsal radial sensory nerve laceration with a true nerve tissue defect,
    Nerve graft repair option for dorsal radial sensory nerve laceration with a true nerve tissue defect,
Symptoms
History of trauma with a laceration in the area of the SDRS nerve (dorsal thumb and/or radial wrist or forearm)
Wound pain, paresthesias and numbness in the dorsal thumb and/or radial wrist or forearm
Typical History

A 26-year-old male was working on an old car when he went to grab onto something for stability and accidentally sliced himself in the process. A sharp piece of metal was protruding from the undercarriage and cut him deeply at the junction of his middle third and distal third of his dorsal radial forearm.  The cut began to bleed severely. The man’s coworker then took him to the ED, where the examination revealed a relatively clean cut and a loss of sensation in the SDRS nerve distribution of his right hand. The patient's wrist deviated ulnarly with attempted wrist dorsiflexion.  The wound was anesthetized with 1% local, and the wound exploration showed a lacerated SDRS nerve and lacerations of the radial wrist extensor tendons. The wound was irrigated, debrided, the skin sutured and a dressing and splint applied. The patient saw a hand surgeon who did a microsurgical SDRS nerve repair and repair of the radial wrist extensor tendons (ECRL and ECRB).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 SDRS nerve laceration, a partial SDRS nerve laceration, or a rare SDRS nerve neuropraxia.
  • Repair the complete or partial nerve laceration.
  • Carefully follow the patient with a SDRS nerve stretch injury; a few patients with neuropraxia will require neurolysis.
  • Improve sensory function of injured upper extremity with a SDRS nerve laceration and decrease the chance of painful neuromas of the SDRS.
Conservative
  • Nonoperative treatment of SDRS nerve complete or partial lacerations is sometimes considered but because the sensory deficit can be acceptable to the patient but usually attempted repair is indicated to minimize t6he chance of neuroma.
  • Isolated SDRS 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 weeks later is reasonable.
  • Neuropraxia of the SDRS nerve secondary to a stretch or contusion injury is very rare, but these injuries could be watched for signs of spontaneous recovery.
  • Other proposed conservative treatment options for isolated SDRS neuromas include repeated local anesthetic blocks with or without delayed action corticosteroid injections, as well as drugs like carbamazepine and mexiletine. When conservative treatments fail, surgery is typically needed.17
Operative
  • Complete SDRS nerve lacerations in civilian practice are usually seen acutely and are usually caused by sharp lacerations from broken glass, knives, saws, or vehicular accidents.  As noted, the primary repair is to minimize the neuroma pain associated with lacerations of the SDRS.
  • 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 may be needed to keep the neuroma-in-continuity away from the thin subcutaneous tissue over the radial styloid.
    4. Nerve repair with nerve conduit
    5. Nerve transfers
  • 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 epineural sheaths.  This can be very difficult in a small SDRS.
  • 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.
  • Successful neurolysis of the SDRS nerve for a neuropraxia is very uncommon.1,6
  • Some surgeons use nerve end or neuroma transposition as the treatment-of-choice for SDRS nerve lacerations, particularly in neglected cases.  Transposition has been found to achieve amelioration of pain in ~70% of patients.8
  • Experts have also recommended direct suturing of the sectioned nerve tips whenever it is possible to join them together without tension. This procedure may or may not be combined with venous sheathing.17   When a tension-free repair is not possible, nerve grafting is typically indicated.4
  • If a painful neuroma develops, treatment should consist of identifying the SDRS nerve neuroma, resecting the SDRS neuroma and placing the proximal nerve stump on the undersurface of the brachioradialis muscle or in an adjacent muscle belly.8
  • Treatment options for dysesthesia following SDRS injury include proximal resection of the nerve, distal posterior interosseous neurectomy, and rarely internal neurolysis with resection of the fibrous tissues.4
Treatment Photos and Diagrams
Dorsal radial sensory nerve laceration repair
  • Dorsal radial sensory nerve laceration (arrow) after trimming of the nerve endings.
    Dorsal radial sensory nerve laceration (arrow) after trimming of the nerve endings.
  • Dorsal radial sensory nerve laceration (arrow) after epieneural repair.
    Dorsal radial sensory nerve laceration (arrow) after epineural repair.
  • Another dorsal radial sensory nerve laceration (arrow) after epineural repair.
    Another dorsal radial sensory nerve laceration (arrow) after epineural repair.
Complications
  • Loss of sensory function
  • Persistent pain and/or paresthesias
  • Neuroma-in-continuity
  • Infection
  • Complex regional pain syndrome
  • There is a strong likelihood for painful neuroma-in-continuity after any surgical repair of SDRS lacerations.8
Outcomes
  • Permanent deficits after nerve repair remain a problem, especially for adults.1
  • Since World War II, the results of nerve repair also have been classified using a grading system designed by the British Medical Research Council.6,18,19  The sensory component of this grading system can be applied to the SDRS nerve repairs but it is more appropriate for the median and ulnar nerve lacerations.  The motor grading system does not apply to the SDRS nerve which has no motor component.

THE MEDICAL RESEARCH COUNCIL SYSTEM6,18,19

Sensory Recovery
S0Absence of sensibility in the autonomous area
S1Recovery 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
S3Return 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
S4Complete recovery
  • Other factors that affect the outcome of SDRS nerve repair include the age of patient (young patients do better); the delay between injury and repair (earlier repairs do better); and the cause of the SDRS nerve laceration (sharp clean cuts do better).1,6
  • In one study, 21 patients with SDRS nerve injuries underwent surgery. Nineteen patients underwent resection of a segment of the SDRS nerve, and 16 (84.2%) experienced significant pain relief.  The 2 patients who underwent external neurolysis following a contusion to the distal forearm experienced poor pain relief.8
  • Another study reported outcomes of patients with SDRS nerve injuries treated surgically: 10 with end-to-end nerve repair, 3 with nerve grafting, and 1 with neurolysis.  Overall, good and excellent sensory results were seen in 10 of 13 patients (76.9%).  Postoperative pain scores were graded as excellent in 69.2% and good in 23.1% of patients, with 12 of the 13 patients (92.3%) returning to their previous occupation.4
Key Educational Points
  • Dry skin (anhydrosis) in the sensory distribution of a potentially cut nerve suggests a complete or partial laceration.
  • MRI can help identify and define nerve tumors, some nerve stretch injuries, and neuromas-in-continuity.1
  • Due to the risk for iatrogenic injury of the SDRS nerve, there is a need for extreme caution when performing wrist surgery, especially during percutaneous procedures that often present with SBRN injuries. Some authors recommend small longitudinal incisions with blunt dissection and lateral separation of soft tissue to the bone plane before introducing K-wires in minimally invasive procedures.20
  • The SDRS nerve is a branch of the radial nerve that travels through the proximal dorsal forearm underneath the brachioradialis and enters the subcutaneous tissues in the interval between the brachioradialis and the extensor carpi radialis longus approximately 9 cm proximal to the tip of the radial styloid.
References

New and Cited Articles

  1. Pederson, WC. Median nerve injury and repair. J Hand Surg Am 2014;39(6):1216-22. PMID: 24862118
  2. Galanakos, SP, Zoubos, AB, Ignatiadis, I, et al. Repair of complete nerve lacerations at the forearm: an outcome study using Rosen-Lundborg protocol. Microsurgery 2011;31(4):253-62.PMID: 21557303
  3. Chemnitz, A, Bjorkman, A, Dahlin, LB, et al. Functional outcome thirty years after median and ulnar nerve repair in childhood and adolescence. J Bone Joint Surg Am 2013;95(4):329-37. PMID: 23426767
  4. Terzis, JK and Konofaos, P. Radial nerve injuries and outcomes: our experience. Plast Reconstr Surg 2011;127(2):739-51. PMID: 20966815
  5. Fernandez, L, Komatsu, DE, Gurevich, M, et al. Emerging Strategies on Adjuvant Therapies for Nerve Recovery. J Hand Surg Am 2018;43(4):368-373. PMID: 29618417
  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, pp. 1035-1092.
  7. Singh, S, Trikha, P and Twyman, R. Superficial radial nerve damage due to Kirschner wiring of the radius. Injury 2005;36(2):330-2. PMID: 15664599
  8. Kim, DH, Kam, AC, Chandika, P, et al. Surgical management and outcome in patients with radial nerve lesions. J Neurosurg 2001;95(4):573-83. PMID: 11596951
  9. Martin, DF, Tolo, VT, Sellers, DS, et al. Radial nerve laceration and retraction associated with a supracondylar fracture of the humerus. J Hand Surg Am 1989;14(3):542-5.PMID: 2544642
  10. Ikiz, ZA and Ucerler, H. Anatomic characteristics and clinical importance of the superficial branch of the radial nerve. Surg Radiol Anat 2004;26(6):453-8.PMID: 15365770
  11. Hurst, LC, Dowd, A, Sampson, SP, et al. Partial lacerations of median and ulnar nerves. J Hand Surg Am 1991;16(2):207-10. PMID: 2022827
  12. Millesi, H. The nerve gap. Theory and clinical practice. Hand Clin 1986;2(4):651-63.PMID: 3539948
  13. Terzis, J, Faibisoff, B and Williams, B. The nerve gap: suture under tension vs. graft. Plast Reconstr Surg 1975;56(2):166-70. PMID: 1096197
  14. Taylor, CA, Braza, D, Rice, JB, et al. The incidence of peripheral nerve injury in extremity trauma. Am J Phys Med Rehabil 2008;87(5):381-5. PMID: 18334923
  15. Lad, SP, Nathan, JK, Schubert, RD, et al. Trends in median, ulnar, radial, and brachioplexus nerve injuries in the United States. Neurosurgery 2010;66(5):953-60.PMID: 20414978
  16. Birch, R, Misra, P, Stewart, MP, et al. Nerve injuries sustained during warfare: part II: Outcomes. J Bone Joint Surg Br 2012;94(4):529-35. PMID: 22434471
  17. Boussakri, H and Meyer Zu Reckendorf, G. Subcutaneous rupture of the superficial branch of the radial nerve at the wrist. A case report and review of literature. Chir Main 2015;34(3):141-4. PMID: 25937310
  18. Seddon HJ. Surgical Disorders of the Peripheral Nerves, ed 7. Edinburgh, Churchill-Livingstone, 1975, pp. 276-280.17.
  19. Seddon HJ (ed): Peripheral Nerve Injuries, Medical Research Council Special Report Series No. 282, London, Her Majesty’s Stationery Office, 1954.
  20. Folberg, CR, Ulson, H, Jr. and Scheidt, RB. The Superficial Branch of the Radial Nerve: A Morphologic Study. Rev Bras Ortop 2009;44(1):69-74. PMID: 26998456
  21. Abrams RA, Brown RA, Bottle MJ. The Superficial Branch of the Radial Nerve: An Anatomic Study with Surgical Complications. J Hand Surg Am 1992;17(6):1037-41.

Review

  1. Boussakri, H and Meyer Zu Reckendorf, G. Subcutaneous rupture of the superficial branch of the radial nerve at the wrist. A case report and review of literature. Chir Main 2015;34(3):141-4. PMID: 25937310
Subscribe to SUPERFICIAL DORSAL RADIAL SENSORY NERVE LACERATION
⇡