Soft tissue, peripheral nerveand brachial plexus injury

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Chapter 20
Soft tissue, peripheral nerveand brachial plexus injury

Beverley Wellington

New Victoria Hospital, Glasgow, UK

Introduction

The aim of this chapter is to provide evidence-based guidance for the assessment, investigation, surgical and conservative care, management and rehabilitation for patients who have sustained a soft tissue injury, peripheral nerve injury or injury to the brachial plexus. Each section will also provide a brief overview of the associated anatomy.

Soft tissue injuries

Soft tissue injuries have several mechanisms of injury but are often caused by either overuse of musculoskeletal soft tissue or a single specific injuring event. The impact on the patient of such injuries can be underestimated and it is important to make a full assessment and follow this with an effective plan of care. Evidence suggests that multiple risk factors, including a genetic predisposition, may be involved particularly in relation to the injuries to the Achilles tendon of the heel, rotator cuff tendons of the shoulder and cruciate ligaments of the knee. In the future, this may allow practitioners to consider genetic risk factors when assessing or treating individuals (Collins and Raleigh 2009).

Ligaments and tendons

Ligaments and tendons are fibrous tissues that have an important role in the musculoskeletal lever system. They are flexible bands of strong, dense connective tissue that connect the articular ends of bones or cartilages together, providing strength and mechanical stability to joints.

Tendons are inelastic fibrous connections between muscles and their points of insertion into bone, transmitting movement forces through joints. They are constructed of fibrous cords which are an extension of the fascia (the fibrous connective tissue found superficially beneath the skin and more deeply which forms a covering sheath for muscles and broad surfaces for muscle attachment). They have no elasticity and are of different lengths and thickness, making them very strong, but with few blood vessels and nerves. Tendons do not cope well with friction and are thus protected at areas of pressure or activity by bursae (sacs filled with a viscous fluid, cushioning movement of one bony part over another) (Hardy and Snaith 2011).

Sprains and strains

Soft tissue injuries are often treated in primary and secondary care settings. Strains and sprains are both soft tissue injures, but the tissue affected is different.

A sprain is an injury to a ligament supporting a joint. A twisting mechanism usually causes damage to fibres of the affected ligament and/or the joint capsule itself, resulting in decreased joint stability. Three grades of ligament injury/sprain are recognised (Altizer 2003):

  • Grade I, Mild – stability is maintained, but can be decreased. The injury is often caused by a wrenching or twisting mechanism and commonly seen at the ankle. The site may be tender with bruising and mild oedema. The patient can usually walk, but with some discomfort.
  • Grade II, Moderate – partial rupture or tear. Some fibres are torn, but some remain intact although with some loss of stability. More than one ligament may be torn, increasing the severity of the injury and affecting the treatment regime that follows. The joint is tender, painful and difficult to move usually with some swelling and bruising.
  • Grade III, Severe – complete rupture with loss of continuity of one or several ligaments. This causes loss of stability and a weakened, painful joint with significantly decreased range of movement. The patient is unable to actively move the joint or to weight bear, and the injury has a significant impact on mobility and activities of living.

A strain is an injury caused by overstretching of the muscle or tendon and may be severe enough to cause a partial or complete tear. These may also be mild, moderate or severe:

  • Mild – pain and stiffness lasting a few days
  • Moderate – partial tears causing more pain and swelling, with bruising with symptoms lasting for 1–3 weeks
  • Severe – complete tears resulting in significant swelling, bruising and pain and often resulting in the need for surgical repair.

Management and care

There are some general principles of management for all soft tissue injuries:

Pain management

The most obvious symptom of soft tissue injury is pain, caused by the traumatic damage to tissue, cell hypoxia and release of chemicals such as histamine, bradykinin and prostaglandin as well as pressure on local nerve endings from swelling in the tissue. Pain relief is usually provided with simple analgesia and non-steroidal anti-inflammatory drugs (Chapter 11). Cryotherapy (the application of cold) has also been shown to have a positive effect on pain relief (Airaksinen et al., 2003) as the cold reduces nerve conductivity.

Control of swelling

Swelling is due to the release of chemicals including prostaglandin, histamine and serotonin which increases the permeability of the cell membrane resulting in protein escaping into the interstitial space. This increases the osmotic pressure and causes increased oedema and associated pain and discomfort. The control of swelling is facilitated by rest, ice, compression and elevation.

Rest, ice, compression and elevation (mnemonic: RICE)

  • Rest. It is important to maintain the normal correct anatomical alignment of the injured structures while immobilising the area until a full clinical examination and diagnosis is made. This will dictate the recovery time that can be expected and the subsequent plan of care. This may include a period of non-weight-bearing or supported weight-bearing with mobility aids, the application of a cast, brace, splint or supporting bandage and advice on when to return to physical activities.
  • Ice. In an acute phase of injury, ice can help reduce pain and inflammation and muscle spasm. It decreases the inflammatory responses and cold-mediated vasoconstriction can help to decrease oedema. Protection of the injured area is important in avoiding ice burns. The ice is best applied frequently for moderate periods of time and for a minimum of three days (Airaksinen et al., 2003).
  • Compression. This can be applied using elastic tubular bandage or equivalent with the aim of controlling the oedema at the injury site and to aid venous return. The evidence for this practice is, however, limited. Care is advised with the amount of compression applied to avoid other complications such as tourniquet effect and compartment syndrome. The aim is to assist with venous and lymphatic drainage and the dispersal of inflammatory fluid whilst preventing an accumulation of oedema.
  • Elevation. This assists in lymphatic and venous drainage and reduces pain by reducing pressure on the capillaries and tissues. The injured part should be elevated above the level of the heart, but caution is advocated with any suspected compartment syndrome.

The goal of treatment, management and rehabilitation is to improve the condition of the injured area to allow a return of functional ability so that the patient can return to full daily activities. Depending on the level of mobility of the patient, significant nursing support may be needed along with assisted personal care.

Peripheral nerve injury

Peripheral nerve injuries are usually associated with another musculoskeletal injury such as a fracture and can have far-reaching effects for the patient. The practitioner needs an understanding of the peripheral nerve supply in order to understand the impact of nerve injury on the patient. Table 20.1 provides a summary of the origins of the main peripheral nerves of the arm.

Table 20.1 The origins of the main peripheral nerves of the arm. Reproduced with permission from Crown copyright

Cord Spinal nerve root Nerve
Posterior C5, C6 Axillary
Posterior C5, C6, C7, C8 Radial
Lateral C5, C6, C7 Musculocutaneous
Lateral and medial C6, C7, C8, T1 Median
Medial C8, T1 Ulnar

Radial nerve injury

The radial nerve is the most commonly injured nerve of the upper limb, often alongside fractures of the humerus. The nerve is derived from spinal nerve roots at level cervical 5 to 8 with contribution from thoracic 1 nerve root. The posterior cord of the brachial plexus is supplied from all 3 trunks of the plexus (upper, middle and lower) and terminates in both radial and axillary nerves. As the radial nerve travels into the arm its direction moves from medial to lateral and it enters near the spiral groove of the humerus running posterolaterally beneath the triceps. It then remains anterior to the humerus and passes anterior to the capitellum at the elbow before dividing at the level of the radial head. This position makes it prone to injury when the arm suffers trauma.

The radial nerve supplies the muscles on the posterior aspect of the arm and forearm. These include triceps brachii (the large muscle on the back of the arm principally responsible for extension of the elbow joint), brachioradialis (muscle of the forearm that acts to flex the forearm at the elbow and facilitates both pronation and supination) and the main muscles that control movements at the wrist as well as sensation to the posterior aspect of the arm and forearm, the radial side of the posterior hand and the dorsum of the fingers.

The causes of radial nerve injury are closely associated with its anatomical position:

  • Radial nerve (and axillary nerve) injury may be caused by incorrectly administered intramuscular injection into the deltoid muscle.
  • Radial nerve palsy can be caused by pressure damage from a spiral fracture of the distal shaft of humerus or from a cast applied too tightly around the mid humerus.
  • Radial nerve neurapraxia can occur following dislocation of the radial head creating a traction-type injury.
  • Radial nerve compression occurs when the arm is left hanging over the side or back of a chair, bed or trolley (often associated with alcohol intoxication and poor sleep posturing). It may also be compressed by the use of axillary/shoulder crutches.
  • Radial nerve palsy can occur post-operatively due to prolonged use of or poor technique in the use of a tourniquet or blood pressure cuff.
  • Other causes include compression by a limb cast, direct trauma to the nerve from an open wound, tumour and idiopathic neuritis.

Patients usually present with weakness in their hand grip and pinch and may also have sensory changes or loss over the dorsum of the thumb and first web space, although this may be minimal due to overlapping of the sensory innervations by other adjacent nerves. Any severe injury causing paralysis of the wrist extensor muscles results in wrist drop, inability to extend the wrist and fingers with a flexion of the hand at the wrist with flaccidity. Conservative management of the wrist drop is provided with a correctly fitting wrist drop support/splint and specific physiotherapy exercises.

Ulnar nerve injury

The ulnar nerve is derived from spinal nerve roots at level cervical 8 to thoracic 1. The medial cord of the brachial plexus is supplied from the lower trunk of the plexus and supplies the ulnar nerve and part of the median nerves. As the ulnar nerve travels into the arm it descends along the posteromedial aspect of the humerus. In the forearm, it enters the anterior (flexor) compartment through the two heads of flexor carpi ulnaris and runs alongside the ulna bone. The nerve also supplies the anteromedial muscles of the forearm and most of the muscles of the hand including the medial side of the hand, little finger and medial half of ring finger.

The causes of ulnar nerve injury are closely associated with its anatomical position and it can be:

  • trapped or pinched as it passes through the cubital tunnel at the elbow
  • damaged in association with fractures to the medial epicondyle of the humerus
  • stretched or compressed when the forearm is extended and pronated.

Patients usually experience paraesthesia in the fourth and fifth digits. They may also be unable to spread the fingers apart, flex the metacarpophalangeal joints or extend the interphalangeal joints. Severe entrapment or complete severing of the ulnar nerve can present with a ‘claw hand’ and hypothenar wasting with an inability to flex the thumb. If cubital tunnel syndrome is diagnosed then surgical management with nerve decompression may be undertaken. Conservative management of ulnar clawing of the fingers is provided with splinting to maintain functional position and specific exercises to prevent further joint stiffness.

Median nerve injury

The median nerve is derived from spinal nerve roots at level cervical 5 to thoracic 1. The medial cord of the brachial plexus is supplied from the lower trunk of the plexus (C8 and T1) and the lateral cord is supplied from the upper and middle trunks of the plexus (C5 to C7). The nerve enters the arm from the axilla and then passes vertically down and alongside the brachial artery along the medial side of the arm between the biceps brachii and brachialis muscles. It moves from being lateral to the artery to lie anterior to the elbow joint and then crosses anteriorly to run medial to the artery in the distal arm and into the cubital fossa, travelling between the flexor muscles before entering the hand through the carpal tunnel. This nerve supplies most of the flexor muscles in the forearm which activate pronation and wrist and finger flexion. In the hand it supplies motor innervation to the first and second lumbrical muscles and also supplies the muscles of the thenar eminence which activate thumb opposition along with sensation to the skin of the lateral side of the palm side of the thumb, the index and middle finger and the lateral half of the ring finger.

The causes of median nerve injury are closely associated with its anatomical position and include:

  • Above the elbow, an injury may result in loss of pronation and a reduction in flexion of the hand at the wrist.
  • At the wrist, an injury by compression at the carpal tunnel causes carpal tunnel syndrome.
  • Severing the median nerve causes median ‘claw hand.’
  • In the hand, the thenar muscles are paralysed and will atrophy over time causing a loss to thumb opposition and flexion.

Patients with carpal tunnel syndrome usually experience paraesthesia (pins and needles and tingling) in the thumb, the index finger, the middle finger and half of the ring finger. They may also present with dull aching and discomfort in the hand, forearm or upper arm. There may also be dry skin, swelling or changes in the skin colour of the hand and eventually weakness in the thumb when trying to bend it at a right angle away from the palm (abduction) with weakness and wasting of the muscles in the thumb.

If carpal tunnel syndrome is diagnosed then surgical management with a nerve decompression may be undertaken. Conservative management is provided with splinting to maintain functional position and specific physiotherapist-led exercises to prevent further joint stiffness. Corticosteroid injection into the joint may provide some temporary relief.

Sciatic nerve injury

The sciatic nerve arises from the sacral plexus from the roots of spinal nerves L4 and L5 and S1 to S3. It is actually two nerves (the tibial and common fibular) that are bound together with a sheath of connective tissue before dividing around the knee region. Injury can result from improperly performed injections into the buttock resulting in sensory loss. It is more commonly associated with pelvic injuries, specifically fractures of the acetabulum with posterior dislocation of the hip joint with displacement through the greater sciatic notch. It can also be damaged during hip arthroplasty surgery when surgical exposure can put the nerve at risk of being damaged or when the hip is dislocated and after the prosthesis is inserted the nerve may be stretched. More rarely the nerve may be damaged by the growth of a Schwannoma (a tumour – usually benign – of the tissue that covers nerves) on the nerve sheath. These tumours develop from a type of cell called a Schwann cell.

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