Is a patient with impaired grip strength and hand function experiencing a transected nerve or a nerve injury, such as an accidental puncture?

Distinguishing Nerve Transection from Nerve Injury

This clinical presentation requires immediate differentiation between complete nerve transection and nerve injury (such as compression, contusion, or accidental puncture), as transection demands urgent surgical repair while other injuries typically respond to conservative management. 1

Clinical Assessment Framework

The distinction between transected and injured nerves depends on mechanism of injury, completeness of functional loss, and timing of presentation. 1, 2

Key Historical Features to Elicit

• Sharp, clean lacerations strongly suggest nerve transection and warrant primary surgical repair, particularly when associated with complete loss of function distal to the injury 1
• Blunt trauma, traction injuries, or compression mechanisms more commonly cause nerve contusion, stretch injury, or neuropraxia rather than complete transection 1, 3
• The temporal relationship matters: immediate complete loss of function after sharp trauma indicates transection, while gradual onset or fluctuating symptoms suggest compression or incomplete injury 3

Physical Examination Findings

• Complete loss of motor function in all muscles innervated by the affected nerve, combined with complete sensory loss in the nerve's distribution, indicates likely transection 1, 2
• Partial preservation of motor or sensory function suggests incomplete injury (compression, contusion, or partial laceration) rather than complete transection 1
• In your patient with impaired (not absent) grip strength, this suggests incomplete nerve injury rather than complete transection 4, 5

Diagnostic Algorithm

Immediate Assessment (Within Days of Injury)

• High-resolution ultrasound can identify nerve transection with 89% sensitivity and 95% specificity, providing rapid diagnostic information when transection is suspected 6
• Ultrasound allows visualization of nerve continuity and can differentiate complete transection from partial injury or compression 6
• The American College of Radiology recommends ultrasound as first-line imaging for suspected nerve pathology due to its high sensitivity and specificity 4

Delayed Assessment (3 Months Post-Injury)

• Electrodiagnostic studies (EMG and nerve conduction studies) become most useful at 3 months when deciding whether surgical repair is needed for injuries that have not recovered 1, 7
• These studies help determine whether nerve continuity exists and whether reinnervation is occurring 1
• For compressed, stretched, or contused nerves without functional recovery by 3 months, surgical exploration is indicated 1

Management Implications

Transected Nerves

• Primary surgical repair is recommended for clean, sharp injuries causing nerve transection, ideally performed urgently 1
• Nerve regeneration occurs at approximately one inch per month, with recovery possible for up to 18 months following injury 1
• Outcomes are better for distal lesions than proximal ones due to the distance nerve must regenerate 1

Nerve Injuries Without Transection

• Initial treatment for compression, contusion, or stretch injuries is nonsurgical 3
• Recovery is more likely with mild injury, shorter duration of compression, and ability to cease aggravating activities 3
• Conservative management for 3 months is appropriate before considering surgical intervention 1

Common Pitfalls

• Do not wait for electrodiagnostic studies if clinical presentation strongly suggests complete transection from sharp trauma—these studies are unreliable in the acute period and delay necessary surgery 1
• Incomplete assessment of motor and sensory function may miss the distinction between complete and partial nerve injury 2
• Some evidence suggests that endoscopic carpal tunnel release increases the risk of nerve injury compared with open release, highlighting that iatrogenic nerve injuries can occur during surgical procedures 8

Application to Your Patient

Given that your patient has impaired (not absent) grip strength, this presentation is more consistent with incomplete nerve injury—such as compression neuropathy, partial nerve injury, or nerve contusion—rather than complete transection. 4, 5 Complete transection would typically present with total loss of motor function in the affected distribution. 1, 2

Consider carpal tunnel syndrome, nerve compression, or partial nerve injury as more likely diagnoses, with ultrasound as the appropriate first-line imaging study. 4, 6