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Ulnar Nerve Injury

From WikiSM

Other Names

  • Ulnar Nerve Injury
  • Ulnar Nerve Laceration
  • Ulnar Nerve Neurapraxia
  • Ulnar Nerve Axonotmesis
  • Ulnar Nerve Neurotmesis

Background

History

  • Unknown, needs to be updated

Epidemiology

  • Most frequent major upper extremity peripheral nerve injury resulting in hospital admission from 1993 to 2006[1]
  • Most commonly affects males age 18 to 45
  • Estimated that the health care cost associated with ulnar nerve injury is $10,563 to $42,000 per individual[2]

Introduction

Compression of the motor branch of the ulnar nerve causes weakness and progressive atrophy of the hypothenar muscles, interosseous muscles, third and fourth lumbricals, adductor pollicis, part of the flexor pollicis brevis[3]
The ulnar nerve contains fibers from C7eT1. After traveling through the cubital tunnel, it supplies the FCU muscle and motor branches to the ulnar half of the FDP muscle. The ulnar nerve then travels the length of the forearm between the FDP and the FDS muscles; sympathetic innervation to the ulnar artery is supplied through the nerve of Henle. A palmar cutaneous branch may also exit the ulnar nerve within the distal forearm to supply sensation to the skin overlying the hypothenar area. PB, palmaris brevis; FPB, flexor pollicis brevis. Inset: The deep branch of the ulnar nerve innervates the interosseous muscles, adductor, and deep head of the flexor pollicus brevis muscle[4]
The ulnar nerve bifurcates into the superficial sensory and deep motor branches in the distal portion of the Guyon canal. Understanding of the topographical anatomy of the ulnar nerve is essential for adequate repair of injuries at the level of the wrist and for performing nerve transfers. Proper matching of the major braches provides the best chance for restoration of sensory and motor function. Inset: Cabled nerve grafts in this area should attempt to match like fascicles[4]
Clinical presentation of the ulnar nerve injury. (A) Representative picture demonstrating the surgical incision in close proximity to the Guyon’s canal; (B) Flattening of the palmar arch of the hand due to a reduction of MCP joint flexion; (C) The occurrence of a positive Froment’s sign is evident as a bending of the distal tip of the thumb when attempting to pinch a piece of paper between the thumb and the index finger[5]

General

  • Typically result from direct trauma at the elbow or wrist
  • Patients typically report sensory loss, paresthesia of the 4th and 5th digit
  • Motor weakness often affects intrinsic hand muscles resulting in muscle atrophy or claw deformity
  • Management can be nonsurgical (neuropraxia) or surgical (axonotmesis or neurotmesis)

Mechanism of Injury (excluding compression neuropathy)

  • Laceration
  • Stretch
  • Contusion

Low vs High Injuries

  • Can be broadly divided into low injuries and high injuries[6]
  • Low injuries
    • Nerve is damaged distal to the motor branch of the FCU, FDP of the ring and little fingers
    • Sensation lost: palmar ulnar hand is lost
    • Paralysis: usually to all 7 interosseous, ulnar 2 lumbrical, 3 hypothenar muscles, adductor pollicis, deep head of the flexor pollicis brevis
    • Sensation to the dorsum of the hand may be intact if the lesion has occurred distal to the takeoff of the dorsal ulnar sensory nerve
  • High Injuries
    • Nerve is damaged above the origin of the motor branch of the FCU, FDP muscles

Anatomy of the Ulnar Nerve

Anatomic Variants of the Ulnar Nerve

  • Richie-Cannieu Communication
  • Martin Gruber Anastomosis
    • Approximately 15% of patients have a motor communication between the median and ulnar nerves[8]

Risk Factors

  • Unknown

Differential Diagnosis

Differential Diagnosis Hand Pain

Clinical Features

Intrinsic Minus

History

  • If trauma was present, patient should be able to describe the trauma
  • They may report weakness, numbness and tingling, particularly in the 4th and 5th digits
  • Often they describe weakness in pinch and grip strength

Physical Exam

  • 4th and 5th digits are highly affected
  • Intrinsic Minus: Loss of intrinsic muscle function results in an inability to flex metacarpal (MCP) joints, extend the interphalangeal (IP) joints
  • Duchennes Sign: hyperextension of MCP joints, flexion of IP joints

Special Tests

Evaluation

raumatic neurotmesis of the ulnar nerve. (a, b) Axial SPAIR PD-weighted image at the level of the middle third of the forearm (a) and coronal STIR image (b) show soft-tissue edema and hemorrhage (white arrow) at the injury site, with thickening of the left ulnar nerve (black arrow) and probable nerve discontinuity (arrowhead in b). (c) Axial diffusion-weighted image shows two hyperintense dots, which correspond to the hematoma (white arrow) and the proximal edge of the left ulnar nerve (black arrow). (d) ADC map shows very low ADC of the hematoma (white arrow), representing a susceptibility artifact due to blood products. The proximal edge of the left ulnar nerve is thickened (black arrow). (e, f) Axial FA maps proximal (e) and distal (f) to the injury site show normal FA (0.4) of the left ulnar nerve (arrow) proximally and reduced FA (0.2) distally owing to loss of axonal integrity.[9]

EMG/ Nerve Conduction Study

  • Critical in determining the level of injury[10]
  • Can be limited in cases of severe axonal loss or early after injury, when neurapraxia cannot be discerned from neurotmesis
  • Can also be limited by pain and an inability to identify anatomical variability

Ultrasound

  • Proposed as a diagnostic tool to aid in identification of peripheral nerve injuries
  • Ultrasound can show individual nerve fascicules
  • Most peripheral nerves can be evaluated along their entire course
  • Can reveal discontinuity, perilesional scar, neuroma with accuracy of 93%[11]

MRI

  • May help identify etiology such as[12]
    • Nerve root avulsion injuries
    • Muscle denervation
    • Nerve edema
    • Sites of compression
    • Nerve disruption

Intraoperative testing of Nerve Action Potentials (NAP)

  • Can be used to determine status of injuries when the nerve is in continuity

Classification

  • Not applicable

Management

Examples of the two splints for ulnar nerve injury. Pictures of the two static splints designed to prevent hand clawing (A) and MCP joints hyperextension (B), respectively.[5]
The injured ulnar nerve is repaired at the injured site (primary or graft repair), and then the branch of the pronator quadratus muscle is transposed to the deep branch of the ulnar nerve at the wrist level (via end-to-end or end-to-side anastomosis). Red arrows indicate where nerve repair is being performed. Abbreviations: MN, median nerve; UN, ulnar nerve; AIN, anterior interosseous nerve; PQ, pronator quadratus; PQB, pronator quadratus branch.[13]

Nonoperative

  • Indications
    • Not entirely clear
    • Can be considered in neuropraxia
    • Reserved for cases without severe or progressive motor deficits
  • Goals of non-surgical management
    • Symptom relief
    • Prevention of further nerve injury
    • Optimizing functional recovery
    • Close monitoring for progression or deterioration
  • Patient education and activity modification
    • Must avoid any provocative positions
  • Splinting/immobilization
    • In a position that protects the nerve from any tension or further injury
  • Physical Therapy

Acute Open Ulnar Nerve Injury

  • Immediate exploration and primary neurorrhaphy
  • Delayed repair can be considered in a contaminated wound
    • Delay increases the likelihood of nerve grafting, neuron loss, fibrosis[14]

Surgical Techniques

  • Primary neurorrhaphy
  • Anterior interosseous nerve (AIN) transfer
  • Tendon transfer for ulnar nerve palsy

Rehab and Return to Play

Application of ultrasound to nerve injuries. An exemplary ulnar nerve injury is shown on the left arm. Distal to the nerve injury, first Wallerian degeneration takes place and subsequent regeneration after successful nerve reconstruction. To support both the injury and proliferative phase, the ultrasound transducer is applied in the course of the nerve, from the injury site to the distal muscle targets for 10 minutes a day.[15]

Rehabilitation

  • General Goals
    • Early, intensive therapy with a hand therapist is crucial to optimize motor and sensory recovery[16]
    • Individualized based on severity, chronicity, location, surgical intervention
    • Prevent contractures, strengthen muscles and maintain range of motion
  • Movements and Techniques
    • Rubber band resistance finger abduction exercises[17]
    • Nerve glide exercises can promote mobility, reduce adhesions[18]
    • Modified constraint-induced movement therapy may be considered to enhance motor function
    • Electrical stimulation to facilitate muscle reinnervation[19]

Return to Play/ Work

  • General rules
    • Must confirm anatomical and functional healing
    • Absence of undue risk to the athlete or others
    • Restoration of sport-specific skills
    • Psychosocial readiness
  • RTP rates
    • Range from 62% to 92% following surgical intervention (need citation)

Prognosis and Complications

Prognosis

  • General
    • Less favorable than for medial nerve injuries
    • Incomplete sensory/motor recovery are common especially after high/ proximal injuries[20]
  • Recovery
    • Motor recovery typically plateaus at 18 to 24 months post injury
    • Persistent deficits in intrinsic hand function, grip strength are common
    • Early, intensive rehabilitation can improve functional outcomes[21]
  • Predictors of better outcome
    • Younger age
    • Distal injury
    • Short delay to surgery
    • Sharp, clean lacerations rather than complex soft tissue injuries
    • Isolated nerve injury
    • Limited posttraumatic stress[22]

Complications

  • Persistent or permanent motor deficits
  • Ulnar Claw Hand Deformity
    • Occurs due to unopposed action of the long finger extensors and flexors[23]
  • Muscle atrophy of the thenar eminence
  • Neuropathic pain, paresthesia
  • Permanent disability
  • Joint contractures and stiffness

See Also

References

  1. ↑ Lad, Shivanand P., et al. "Trends in median, ulnar, radial, and brachioplexus nerve injuries in the United States." Neurosurgery 66.5 (2010): 953-960.
  2. ↑ Rosberg, HansE, et al. "Injury to the human median and ulnar nerves in the forearm–analysis of costs for treatment and rehabilitation of 69 patients in southern Sweden." Journal of hand surgery 30.1 (2005): 35-39.
  3. ↑ Saracco, Michela, et al. "Isolated compression of the ulnar motor branch due to carpal joint ganglia: clinical series, surgical technique and postoperative outcomes." European Journal of Orthopaedic Surgery & Traumatology 31.3 (2021): 579-585.
  4. ↑ 4.0 4.1 Woo, Alice, Karim Bakri, and Steven L. Moran. "Management of ulnar nerve injuries." The Journal of hand surgery 40.1 (2015): 173-181.
  5. ↑ 5.0 5.1 Fulceri, Federica, et al. "Early post-surgical rehabilitation and functional outcomes of a traumatic ulnar nerve injury: a pediatric case report." Frontiers in Neurology 15 (2024): 1351407.
  6. ↑ Jones, Neil F., and Gustavo R. Machado. "Tendon transfers for radial, median, and ulnar nerve injuries: current surgical techniques." Clinics in plastic surgery 38.4 (2011): 621-642.
  7. ↑ Gross MS, Gelberman RH. The anatomy of the distal ulnar tunnel. Clin Orthop Rel Res. 1985;196:238e247.
  8. ↑ Slutsky, David J., ed. Upper extremity nerve repair-tips and techniques: a master skills publication. Amer Soc Of Surgery of the Hand, 2008.
  9. ↑ Martín Noguerol, Teodoro, et al. "Functional MR neurography in evaluation of peripheral nerve trauma and postsurgical assessment." Radiographics 39.2 (2019): 427-446.
  10. ↑ Don Griot, J. Peter W., J. Joris Hage, and Peter JM De Groot. "Digital innervation patterns following median or ulnar nerve laceration and their correlation to anatomic variations of the communicating branch between these nerves." Journal of Hand Surgery 29.4 (2004): 351-355.
  11. ↑ Zhu, Jiaan, et al. "Preliminary study of the types of traumatic peripheral nerve injuries by ultrasound." European radiology 21.5 (2011): 1097-1101.
  12. ↑ Grant, Gerald A., et al. "MR neurography: diagnostic utility in the surgical treatment of peripheral nerve disorders." Neuroimaging Clinics 14.1 (2004): 115-133.
  13. ↑ Ding, Wenquan, et al. "Repair method for complete high ulnar nerve injury based on nerve magnified regeneration." Therapeutics and Clinical Risk Management (2020): 155-168.
  14. ↑ Lundborg, Göran. "A 25-year perspective of peripheral nerve surgery: evolving neuroscientific concepts and clinical significance." The Journal of hand surgery 25.3 (2000): 391-414.
  15. ↑ Bergmeister, Konstantin D., et al. "Promoting axonal regeneration following nerve surgery: a perspective on ultrasound treatment for nerve injuries." Neural regeneration research 13.9 (2018): 1530-1533.
  16. ↑ Fulceri, Federica, et al. "Early post-surgical rehabilitation and functional outcomes of a traumatic ulnar nerve injury: a pediatric case report." Frontiers in Neurology 15 (2024): 1351407.
  17. ↑ Boudreau, Colton, et al. "A comparative study using electromyography to assess hand exercises for rehabilitation after ulnar nerve decompression." Journal of Plastic, Reconstructive & Aesthetic Surgery 75.1 (2022): 307-313.
  18. ↑ Mezian, Kamal, et al. "Ulnar neuropathy at the elbow: from ultrasound scanning to treatment." Frontiers in neurology 12 (2021): 661441.
  19. ↑ Caliandro, Pietro, et al. "Treatment for ulnar neuropathy at the elbow." Cochrane database of systematic reviews 4 (2025).
  20. ↑ Lan, Ching-Yu, et al. "Prognosis of traumatic ulnar nerve injuries: a systematic review." Annals of plastic surgery 82.1S (2019): S45-S52.
  21. ↑ Ruijs, Aleid CJ, et al. "Median and ulnar nerve injuries: a meta-analysis of predictors of motor and sensory recovery after modern microsurgical nerve repair." Plastic and reconstructive surgery 116.2 (2005): 484-494.
  22. ↑ Hundepool, Caroline A., et al. "Prognostic factors for outcome after median, ulnar, and combined median–ulnar nerve injuries: A prospective study." Journal of Plastic, Reconstructive & Aesthetic Surgery 68.1 (2015): 1-8.
  23. ↑ Bertelli, Jayme Augusto. "Prior to repair functional deficits in above-and below-elbow ulnar nerve injury." The Journal of Hand Surgery 45.6 (2020): 552-e1.
Created by:
John Kiel on 14 June 2019 08:37:18
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Last edited:
19 November 2025 18:57:52
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