Rehabilitation of Peripheral Nerve Injuries in Disasters and Conflicts

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Original Editors - Naomi O'Reilly

Top Contributors - Naomi O'Reilly, Tarina van der Stockt, Kim Jackson and Jess Bell      

Introduction

Peripheral nerves can sustain injury from numerous causes including traumatic thermal, chemical, or mechanical injury, inherited causes, infections, collagen or metabolic diseases (diabetes mellitus being one of the most common), exposure to endogenous or exogenous toxins; malignancies and iatrogenic causes, which manifest with neurological deficits distal to the level of the lesion. In disaster and conflict situations there can be a significant increase in the number of traumatic peripheral nerve injuries, but all of these other causes of nerve injury will continue to be seen by patients in these situations. In disaster and conflict situations patients with peripheral nerve injuries tend to present with other injuries, often complex and most frequently associated with limb fractures. In many cases these associated injuries need stabilised prior to the peripheral nerve injury being treated, which can often result in a delay in identification and treatment of the peripheral nerve injury.

Disasters including earthquakes and storms can lead to large numbers of peripheral nerve injuries, as a result of complex limb trauma and crush injuries, or those which incur deep soft tissue injuries from flying debris, while in conflict situations, peripheral nerve injuries are also associated with complex injuries as a result of explosives devices, gunshot wounds, and penetrating injuries. Primary injury to the nerve is generally a result of the same trauma that injures the bone or joint, but can also occur as a result of moving the patient or stretching, or manipulation of the limb while treating the injury, rather than by the initial force. Infection, scar, callus, or vascular complications including haematoma, arteriovenous fistula, ischemia, or aneurysm can also result in secondary injury to the nerve.

In the upper limb radial nerve injuries are most the common with 14% associated with humeral shaft fractures, 3% associated with fracture of the middle third of the humerus; 50%, with fracture of the distal third of the humerus; 7%, with supracondylar fracture of the humerus; and 7%, with dislocation of the radial head, while in shoulder dislocations it is the axillary nerve that may be injured as a result of stretch injuries, although this is rare and only occurs in about 5% of shoulder dislocations. Ulnar injuries account for 30% of patients with combined skeletal and neural injuries to the upper limb, and are generally associated with fractures of the medial humeral epicondyle, but often as a result of callus formation around the elbow. While elbow dislocations tend to result in median nerve injury in about 15% of combined skeletal and neural injuries of the upper limb, or after injury to the distal forearm of wrist. In the lower limb it is the peroneal nerve that is most commonly injured at the fibular neck, as a result of fracture of the tibia and fibula or dislocation of the knee, while the tibial nerve is injured more in distal fractures of the tibia or ankle. Lumbosacral plexus branches are injured in in less than 3% of pelvic fractures; and in 10% to 13% of posterior dislocations of the hip.

In conflict situations nerve injuries are generally distributed evenly between the upper and lower limbs, with explosions (63%) the main cause of peripheral nerve injury with 82% nerve injuries associated with open injuries, and a portion of patients presenting with injury to two or more nerves. Neurapraxia (45%) is the most common type of injury to the nerve, followed by axonotmesis (35%) and neurotmesis (20%). The ulnar, common peroneal and tibial nerves were most commonly injured, and in a large portion of these injuries was associated with a vascular injury, fracture, or both at the level of the nerve lesion, which is a small number of situation s result in amputation secondary to major tissue loss and the level of nerve damage.

In disaster and conflict situations peripheral nerve injuries can be missed when medical or surgical team prioritise working to save limb or life, and rehabilitation professionals are often the first member of the team to identify possible nerve complications during their assessment and treatment. As such rehabilitation professionals should always ensure that every patient who has injured a limb or limb girdle should be evaluated and monitored for any possible peripheral nerve damage, in particular post surgery, manipulation, casting, and recovery from skeletal injury to detect any possible secondary neural injury. Early rehabilitation plays a key role in the management of peripheral nerve injuries, with education key to minimise possible complications and maximise independent function.

Peripheral Nerve Injury Overview

The peripheral nervous system is comprised of three types of cells: neuronal cells, glial cells, and stromal cells. Peripheral nerves convey signals between the spinal cord and the rest of the body. Nerves are comprised of various combinations of motor, sensory, and autonomic neurons. Efferent neurons (motor and autonomic) receive signals through their dendrites from neurons of the central nervous system, primarily using the neurotransmitter acetylcholine among others. Afferent (sensory) neurons receive their signals through their dendrites from specialized cell types, such as Paccinian corpuscles for fine sensation and others. These signals are sent to the CNS to provide sensory information to the brain and possibly interneurons in the spinal cord when a reflex response is necessary1.

A peripheral nerve injury can result in a minor injury or a fully severed nerve. Based on the type and amount of damage, nerve regeneration may or may not be possible. Peripheral nerve Injury treatment depends on the type of injury, symptoms and the amount of nerve injury sustained.

Classification of Peripheral Nerve Injuries

Classification systems provides a common language for medical and rehabilitation professionals to effectively discuss nerve pathophysiology. There are two commonly used classification systems in use for peripheral nerve injury; the Seddon Classification and the Sunderland Classification. Seddon was the first to classify nerve injuries into three categories; neurapraxia, axonotmesis, and neurotmesis, based on the presence of demyelination and the extent of damage to the axons and the connective tissues of the nerve. Sunderland later expanded on this initial classification to distinguish the extent of damage in the connective tissues. McKennon and Dellon introduced a further classification to denote combinations of Grade III-V injuries along the route of the damaged nerve, although it is not as widely accepted in use.

Table.1 Peripheral Nerve Injury Classification Systems

Seddon Classification	Sunderland Classification	McKennon & Dellon	Type of Injury	Potential for Recovery
Neuropraxia	Grade I		Local myelin damage usually secondary to compression. The whole nerve remains structurally intact.	High likelihood for full recovery
Axonotmesis	Grade II		Axon severed Endoneurium intact	Good likelihood of full recovery
	Grade III		Axon discontinuity, endoneurial tube discontinuity. Perineurium and fascicular arrangement preserved	Potential for recovery, but will likely be slow, with less than 100% recovery. Surgery may be required
	Grade IV		Loss of continuity of axons, endoneurial tubes, Perineurium and fasciculi; epineurium intact	Requires surgical intervention
Neurotmesis	Grade V		Complete Nerve Transection Total physiologic disruption of entire nerve trunk	The chances of recovery are very poor without surgical repair.
		Grade VI	Mixed levels of injury along the nerve

Common Peripheral Nerve Injuries

Upper Limb

Nerve	Related Injuries	Muscle Affected	Motor Function	Sensation	Test
Spinal Accessory Nerve	Fracture Atlas or Hyoid Neck Trauma	Trapezius	Elevates Pectoral Girdle Retracts Scapula Depresses Shoulder Ipsilateral side flexion of neck		Posture Scapular Winging at Rest Assess Abduction Test Hand behind back and lift hand away from back
Long Thoracic Nerve	Sudden Scapular Depression Axillary Crutch Use	Serratus Anterior	Scapula Protraction Upward Scapular Rotation		Scapular Winging with Movement
Axillary Nerve	Most common peripheral nerve injury to affect the shoulder. Fracture Shoulder Dislocation Shoulder	Deltoid Teres Minor	Abduction from 15° Shoulder Extension Shoulder Flexion External Rotation Atrophy Deltoid - Flat Shoulder	Regimental Patch	Unable to Abduct Arm to 90 degrees Unable to maintain resisted abduction at 90 degrees
Suprascapular Nerve	Shoulder Fracture Clavicular Fracture Proximal Humeral Fracture	Infraspinatus Supraspinatus	Initial 15° Abduction External Rotation Atrophy Supraspinatus and/or Infraspinatus		Infraspinatus Test Suprascapular Nerve Stretch Test
Musculocutaneous Nerve	Isolated injury to the Musculocutaneous Nerve is rare Knife wound to Axilla	Biceps Brachii Brachialis Coracobrachialis	Elbow Flexion Supination Weak or Absent Biceps Tendon Reflex Atrophy Anterior Compartment Arm	Lateral and Volar Aspect of  the Forearm	Unable to Flex Elbow
Ulnar Nerve	At risk of Injury at Medial Epicondyle, in Cubital Tunnel, or at the Wrist; Fracture Elbow Dislocation Elbow Laceration at Wrist	Forearm: Flexor Carpi Ulnaris Flexor Digitorum Profundus	High Lesion - Ulnar Paradox; Hyperextension 4th & 5th Finger at MCP Joint Paralysis 4th & 5th Finger at IP Joint; Straighter Fingers Loss Ulnar Deviation Loss of FCU Tendon on Ulna Flexion Loss Interossei Function Loss Thumb Adduction Wasting Hypothenar Eminence Wasting Interossei	Palmar Surface of 5th & ½ 4th Digit Dorsal Surface of 5th & ½ 4th Digit	Inability to cross second and third finger Poor Grasp and Release
		Hand Hypothenar Eminence; Abductor Digiti Minimi Flexor Digiti Minimi Opponens Digiti Minimi Thenar Eminence; Adductor Pollicis Short Muscles; Lumbrical 3 & 4 Dorsal Interossei Palmar Interossei Palmaris Brevis	Low Lesion - Partial Claw Hand; Hyperextension 4th & 5th Finger at MCP Joint Flexion 4th & 5th Finger at IP Joint Loss Interossei Function Loss Thumb Adduction Wasting Hypothenar Eminence Wasting Interossei		Inability to cross second and third finger Poor Grasp and Release Partial Claw Hand
Radial Nerve	Humeral Fracture Elbow Fractures Elbow Wounds	Arm Triceps Brachii Anconeus             Extensor Indicis	High Lesion; Loss Elbow Extension Loss Wrist Extension Loss Hand Extension Loss Radial Deviation Atrophy Forearm	No Sensory Involvement if Posterior Interosseous Branch is Damaged Alone 1st Webspace; Dorsum Aspect Hand from 1st to ½ 4th Digit	Wrist Drop Present
		Forearm; Brachioradialis Extensor Carpi Radialis Longus Extensor Carpi Radialis Brevis Supinator Extensor Digitorum Extensor Digiti Minimi Extensor Carpi Ulnaris Abductor Pollicis Longus Extensor Pollicis Longus Extensor Pollicis Brevis	Middle & Low Lesion; Loss Wrist Extension Loss Hand Extension Loss Radial Deviation Loss Thumb Extension Atrophy Forearm
Median Nerve	Supracondylar Humeral Fractures	Forearm; Pronator Teres Flexor Carpi Radialis Palmaris Longus Flexor Digitorum Superficialis Flexor Digitorum Profundus Flexor Pollicis Longus Pronator Quadratus	High Lesion; Loss Wrist Flexion Loss of Opponens Loss of Ulnar Deviation Wasting of Thenar Eminence	Palmar Aspect 1st - ½ 4th Ring Finger	Ok Test Pinch Test
			Low Lesion; Long Flexors Unaffected Loss of Opponens Thenar Muscle Wasting
		Hand; LOAF Lumbricals 1 & 2 Opponens Pollicis Abductor Pollicis Flexor Pollicis	Carpal Tunnel; Wasting of Thenar Eminence; Weakness Abductor Pollicis Brevis Loss of Opponens

Lower Limb

Nerve	Related Injuries	Muscle Affected	Motor Function	Sensation	Test
Gluteal Nerve		Gluteus Medius	Hip Abduction		Trendelenburg Sign
Femoral Nerve	Fracture Hip Fracture Pelvis Acetabular Fracture Stab Wounds Gunshot Wounds Prolonged Pressure on nerve	Quadriceps	Flexion Hip Extension Knee	Anterior Thigh Medial Thigh Medial Leg to Hallux (Great Toe)	Difficulty straightening knee
Tibial Nerve	Dislocation Knee Fracture Tibia Fracture Fibula Laceration Injury	Popliteus Gastrocnemius Soleus Plantaris Flexor Digitorum Longus Flexor Hallucis Longus			Unable to walk on toes
Peroneal Nerve	Dislocation Knee Fracture Fibular Head	Biceps Femoris Tibialis Anterior			Unable to walk on heels

Resources

Early Rehabilitation in Conflict and Disasters, Humanity and Inclusion

Rehabilitation in Sudden Onset Disasters, Humanity and Inclusion