What is the next step in management for a patient with no wrist motor function following a needle stick injury to the deltoid muscle, with no signs of infection or edema?

Management of Wrist Motor Dysfunction Following Needle Stick Injury

The next step is to obtain MRI of the wrist without IV contrast to evaluate for nerve injury, specifically radial nerve damage, followed by initiation of a structured occupational therapy program with dynamic splinting and functional electrical stimulation while awaiting imaging results. 1, 2

Immediate Diagnostic Workup

Advanced Imaging

• MRI with dedicated neurography sequences (e.g., diffusion weighted) is the imaging modality of choice for suspected traumatic nerve injury of the hand and wrist, as it provides improved visualization of injured nerves 1
• MRI without IV contrast or ultrasound are equivalent alternatives for evaluating suspected tendon or ligament trauma when initial radiographs are negative or equivocal 1
• Electrodiagnostic studies (EMG/NCS) should be performed by a physician with comprehensive neuromuscular training to identify the area of nerve entrapment and extent of pathology, though these are typically performed 3-4 weeks post-injury to allow Wallerian degeneration 3, 4

Critical Pitfall: Do not rely on nerve conduction studies alone without needle EMG, as this provides incomplete diagnostic information and can lead to missed diagnoses of radiculopathy, plexopathy, or motor nerve disorders 3

Concurrent Therapeutic Interventions

Primary Rehabilitation Strategy

• Initiate a structured occupational therapy program focused on functional task training with normal movement patterns immediately, even before imaging confirmation 2
• Implement dynamic splinting that provides wrist and finger extension support through a tenodesis mechanism 2
• Avoid static immobilization or serial casting, as this worsens symptoms, causes muscle deconditioning, promotes learned non-use, and can trigger complex regional pain syndrome 2, 5

Functional Electrical Stimulation

• FES should be initiated for patients with demonstrated impaired muscle contraction and wrist motor impairment, as it provides short-term increases in motor strength and motor control 1, 2, 6
• FES is most effective when initiated within the first 6 months post-injury 6
• Evidence shows improved muscle force in wrist extension when used as adjunctive therapy during the recovery period 1, 6

Home Exercise Program

• Prescribe a directed home exercise program as the primary therapy modality, including active finger motion exercises and stretching exercises for wrist flexors and extensors 2
• Grade activities progressively to increase the time the affected hand is used within functional tasks, employing normal movement techniques and avoiding compensatory strategies 2, 5
• Perform functional tasks that promote normal movement, proper alignment, and even weight-bearing of the affected hand, including using the hand to stabilize objects during activities 2

Monitoring and Follow-Up

• Reassess function every 2-3 weeks to evaluate splint effectiveness, adjust therapy progression, and monitor for adverse effects from splinting 2
• Recovery assessment should extend beyond 90 days, as emerging data confirms that recovery takes longer than traditionally assumed, with 6-12 months being more appropriate for final functional assessment 1
• Video recording interventions (with consent) can demonstrate changeability in symptoms and serve as reference points for replicating successful strategies 2

Important Consideration: While the injury was to the deltoid muscle region, the absence of wrist motor function suggests either radial nerve injury from the needle stick or a more proximal nerve injury affecting the posterior cord or C5-C6 nerve roots. The pattern of deficit (isolated wrist motor loss without infection or edema) is atypical for a simple deltoid injury and warrants thorough neurovascular evaluation 7