Peripheral Nerve Injury By Dr. Malik Irfan Ahmed Senior Registrar Surgery DHQ Hospital.

Anatomy Connective tissue - major tissue componant - epineurium, perineurium, endoneurium Nerve tissue - axon, schwann cell

Peripheral Nerve Injury Acute injury Chronic injury (entrapment neuropathy)

Classification

Neuropraxia The mildest form, reversible conduction Block Loss of function, which persists for hours Or days Direct mechanical compression, ischemia, Mild burn trauma or stretch

Axontmetic axon continuity is disrupted fascicular integrity is maintained Wallerian degeneration occurs

Neurotmesis Laceration from sharp or blunt forces The only important consideration is the timing of repair Acute repair or more bluntly lacerated Nerves are repaired 3-4 weeks

Factor s for Decision Making Age Segment between injury and end organ Gap of injury Mechanism of injury Severity of injury Presence of pain

Axonal Regeneration Initial delay to the distal stump : 1-2 week delay Growth rate 1mm/day, 1 inch/month Terminal delay several weeks-several months Recovery within 6 weeks good prognosis

Electrophysiological Tests Diagnosis Electrophysiological Tests EMG SNAP(sensory nerve action potential) SSEP(Somatosensory evoked potentials) Intraoperative NAP

Treatment Time of Operation Open injury Early intervention Delayed intervention Closed injury

Early Intervention Enlarging hematoma/aneurysmal sac Predisposing to Volkmann’s ischemic contracture Severe noncausalsic pain SD Injury to N. in areas of potential entrapment Simple, clean lacerating injury

Delayed Intervention 2-3 months after injury No clinical or substantial recovery

Operations Neurolysis : internal/external Nerve repair end-to-end repair : epineural/fascicular autologous graft : sural N. Neurotization intercostal N./accessory N./cervical plexus within 1 year Muscle and tendon transfer

PRINCIPLES OF NERVE REPAIR l. Quantitative assessment 2. Microsurgical technique 3. Tension-free repair 4. Primary repair is performed when feasible. 5.nerve graft

6. Postural maneuvers cannot substitute for a tension-free repairwith grafting 8. Repair is delayed for a minimum of 3 week 9. Postoperative early movement 10. Preoperativep hysicalt herapy

Epineural Repair

Fascicular Repair

Nerve Graft # leading cause of failure of nerve graft Inadequate resection Distraction of repair site

Postoperative Care Neurolysis : End-to-end repair : Graft :

Injured Peripheral Nerve

Evaluation of Closed Injury

Conclusions 1. Immediate primary repair in sharp injuries with suspected transsection of nerve Immediate repair is especially important for brachial plexus and sciatic nerve transsections because delay leads not only to retraction but also to severe scaring Bluntly transsected nerve best repaired after a delay of several weeks. A focally injured nerve should be explored if no functional return within 8-10 weeks 3. Decision - making as to whether neurolysis or resection & repair in a lesion in gross continuity based on intraoperative electrophysiological evaluation

Chronic Injuries of Peripheral Nerves by Entrapment Pain Paresthesia Loss of function

Pathophysiology of Entrapment Direct compression segmental demyelination wallerian degeneration(distal) Ischemia swelling of nerve microcompartment SD

Treatment Conservative Tx Indications not long history mild-moderate, intermittent reversible cause pregnancy, oral contraceptive, endocrine abnormalities(DM…), type writer Method nonsteroidal anti-inflammatory drugs splint

Treatment Surgical Indications Failed conservative tx Typical clinical finding with electrodiagnostic data Severe sensory loss muscle atrophy motor weakness

Entrapment of Thoracic Outlet - Cervial rib or anomalous transverse process of C7 - Fibromuscular bands or scalene muscle abnomality - X-ray - NCV & EMG - Angiography – vascular anomaly Tx : Supraclavicular approach - Best op. management

scalene anterior and medius M.

Carpal Tunnel Syndrome

thenal atrophy

Entrapment of Radial Nerve

Entrapment of Ulnar Nerve - Cubital tunnel - Guyon’s canal

Motor Deficit of Ulnar Nerve Bediction posture : clawing of ring & small finger Froment’s sign : weakness of adductor pollicis, there will be flexion of the interphalangeal joint of the thumb because of substitution of the median innervated flexior pollicus longus for a weak adductor pollicis

Meralgia Paresthesia Lateral femoral cutaneous nerve injury (L1-2)

Tarsal Tunnel Syndrome