PERIPHERAL NERVE INJURIES By: M. Rustom General, Plastic & Reconstructive Surgeon MRCS (London) Ms Surg/Plastic, Malaya Fellowship in Plastic & Reconstructive Surgery, Malaya

Contents Overview Anatomy Pathophysiology Classification Mechanism of Injury Clinical Presentation Management Prognosis

Peripheral nerve injuries may result in loss of motor function, sensory function, or both. Paul of Aegina (625-690) was the first to describe approximation of the nerve ends with wound closure. Hueter (1871, 1873) introduced the concept of primary epineurial nerve suture. Loebke described bone shortening to decrease nerve tension in 1884. In 1876, Albert described grafting nerve gaps. Egloff and Narakas, 1983 were the 1st to discuss the use of Fibrin glue as an alternative to the classic suture repair method. Overview

Anatomy

PATHOPHYSIOLOGY May result in demyelination, axonal degeneration, or both. Disruption of sensory, motor function or both depending on the location & the severity of the injury. Recovery is influenced by the capacity of remyelination, axonal regeneration & reinnervation of the nerve ending units. Wallerian degeneration. Schwann cell proliferation. Axonal sprouting.

MECHANISM OF INJURY Stretching injury: - 8% elongation will diminish nerve's microcirculation - 15% elongation will disrupt axons Compression or crush injury: - local ischemia. - Local toxic metabolites. - External pressure: 30mm Hg can cause paresthesias . 60 mm Hg can cause complete block of conduction

MECHANIS OF INJURY Laceration nerve damage: - continuity of nerve disrupted, leading to : . Ends retract . Nerve stops producing neurotransmitters . Nerve starts producing proteins for axonal regeneration

CAUSES Trauma. Prolong ischemia Excessive traction Surgical / Iatrogenic Metabolic Acute compression Thermal injury Electrical injury CAUSES

TYPES

CLASSIFICATION

CLASSIFICATION

CLASSIFICATION

Depends on the location & the nerve involved. Sensory deficit Motor deficit Autonomic deficit Combination CLINICAL PRESENTAION

CLINICAL PRESENTAION Requires high index of suspicion Overdiagnosis is better than underdiagnosis In axonotmesis early intervention is directly related to the prognosis Positive Tinnels’s test indicate urgent surgery

WORK UP

Surgical causes of compression MANAGEMENT Observation: Neurobraxia Axonotmesis Surgical repair Neurotmesis Surgical causes of compression Nerve grafting Wide gap Segmental loss

PROGNOSIS