PBL Write Up – Locomotor 2: The Incident with The Grandson
Nathan Sie Yiu Leung
Cardiorespiratory, Metabolism, Locomotor
18th February 2017
Student Number: 160184242
Word Count:
Introduction
In this PBL scenario, Charmilie is brought into the Emergency Department Unit after experiencing severe pain on the anterior side of her upper right arm. She claims that she was hit in the upper right arm by a toy truck last week whilst looking after her 3-year-old grandson. There was swelling and bruising for over 6 days, and paracetamol was not relieving any pains. Clinical testing, ultrasound showed that there was an apparent haematoma (4cmx5cmx20cm) on the anterior side; above the biceps brachii muscle. Charmilie also suffered from wrist drop, unable to flex her fingers into a fist. She had lost complete sensory function to her right hand and could not sense any pain. There were however Ulnar and Radial pulses at the wrist. For treatment, anterior and posterior fasciotomy was performed, two drains used and primary wound closure executed. Within 24 hours, there was sensation in her right wrist. Flexors of the fingers started to function, but not quite full strength. There was no improvement of her wrist drop.
Diagnosis
Charmilie suffers from acute compartment syndrome. Compartment syndrome is increased pressure in the muscular compartment of the limbs [I]. There are two types: Acute and chronic. In this particular case, Charmilie has acute compartment syndrome, after experiencing damage to her upper arm (biceps brachii fracture). The cause of her pain is due to the hematoma leaking blood outside of blood vessels within muscular compartments. As a consequence, there is blood build up within the anterior muscular compartments of the arm, building up pressure. Without treatment, there is possible Ischemia and potential damage to the nerve and blood supply to muscles. She has lost sensory and motor innervation to her wrist, because the nerves are compressed. Her wrist drop is also an indicator for Radial nerve damage (Radial nerve palsy).
For patients, it is hard to differentiate the pain between fracture and internal bleeding. Prognosis can even be as severe as losing of a limb if left too late.
Learning Objectives:
• Key terms
• Upper limb
– Deep Fascia
– Muscle compartments and Function
– Innervation
– Blood Supply
• Treatment
– Fasciotomy
Key terms
Hematoma
A hematoma is the accumulation of blood build up on the outside of a blood vessel, leading to swelling. The size of the hematoma depends on how big/ major the artery, blood vessel, capillary or vein is. It is primarily caused by damage to the blood vessel walls.
Muscle Compartments
A compartment containing muscle groups. Their nerve supply and blood supply is protected by deep fascia.
Fasciotomy
A surgical incision, releasing and relieving pressure and tension within muscle compartments; the treatment for acute compartment syndrome. The prognosis is usually the regaining of nerve innervation and blood supply.
Anterolateral incision
An incision performed at the front. The cut is made away from the sagittal midline.
Wrist drop
Also known as radial nerve palsy, it is the inability to extend the wrist backwards, resulting in the wrist hanging flaccidly.
Upper Limb
Deep Fascia
Deep fascia is a tough, inelastic dense fibrous connective tissue that envelops muscle compartments, nerves, blood supply and bones in the limbs & tissues of the body. It is more prominent and developed in the limbs, forming tight slots & sleeves and less defined in the face [II].
Common functions of deep fascia include [II]:
1.
Aiding venous and lymphatic return to the heart. The deep veins underlie the deep fascia and the fascia forms septa between muscles to squeeze blood superiorly back up veins.
2. Helps with muscle movement by generating pressure and tension on
surfaces.
3. One of the main functions of deep fascia is to keep muscles, bones, nerves and blood vessels in place. It can protect these structures in the neck and limbs.
4.
Provides area for muscular attachment.
5. Forms an epineurium around nerves, protecting them.
6. Protects the tendon from degradation by forming tendon sheaths.
The haematoma is located on the anterior surface of the arm, just above the cubital fossa. Leakage outside blood vessels is caused by the build-up of pressure in the muscular compartments, because the superficial and deep fascia are unable to expand. Their thick and inelastic properties make them less flexible, and their compliance to stretch is reduced. The increasing pressure in the muscular compartments can be painful and is otherwise known as compartment syndrome. Approximately 75% of cases are a result of fractures to the limbs [III]. The scenario strongly suggests that the toy truck has caused damage to the upper arm and as a result of pressure build up, bursting of capillaries and major vessels.
Muscle Compartments
Anterior Compartment of the Arm
The anterior compartment is located just underneath the superficial layers of the upper arm. This compartment of muscles is mainly used for flexion of the elbow. It consists of three main muscles – Biceps Brachii; Brachialis; Coracobrachialis. Coracobrachialis is not involved in elbow flexion but instead involved in adduction and flexion of the glenohumeral joint [IV].
Biceps Brachii
Biceps brachii is a two headed muscle located anteriorly to the humerus, but not directly attached to it. Its main function is for flexion of the elbow and supination of the forearm. The biceps brachii tendon test is mainly spinal nerve C6 innervation, but the biceps brachii muscle is supplied by the musculocutaneous nerve.
Brachialis
Brachialis muscle lies inferiorly to the biceps brachii muscle, but more distal to other muscles. It’s function in the upper arm is for elbow flexion. It is also innervated by the musculocutaneous nerve, as well as the radial nerve.
Coracobrachialis
Similarly, Coracobrachialis lies deep to the biceps brachii muscle. The muscle begins at the coracoid process of the scapula, and attaches to the medial side of the humerus. Its primary role is for flexion of the glenohumeral joint and weak adduction of the arm. Its innervation comes from the musculocutaneous nerve.
Posterior Compartment of the Arm
The posterior compartment of the arm is known as the extensor compartment and can be found at the back of the arm. It contains the Triceps Brachii and the Anconeus, muscles responsible for extension of the elbow.
Triceps Brachii
Triceps Brachii is a three headed muscle that originates at the infraglenoid part of the Scapula. It divides the axillary space into two halves by passing through the Teres Major and Teres Minor. The three heads converge into one thick tendon at the olecranon at the elbow joint. The subtendinous bursa of triceps brachii lies underneath the tendon, preventing friction between the olecranon. It is involved in extension of the elbow and innervated by the musculocutaneous nerve [V].
Anterior Compartments of the Forearm
The anterior compartment of the forearm is generally used for flexion of the wrist & fingers, and pronation of be split into 3 different subcategories: Superficial, Intermediate and Deep. Flexor Carpi Ulnaris, Flexor Carpi Radialis, Pronator Teres and Palmaris Longus all lie within the superficial compartment. They originate from a mutual tendon from the medial epicondyle of the humerus. Flexor Carpi Ulnaris flexes and adducts the wrist and is innervated by the ulnar nerve. Flexor Carpi Radialis flexes and abducts the risk and is innervated by the median nerve. Pronator Teres and Palmaris Longus are also innervated by the median nerve but Pronator Teres pronates the forearm medially and Palmaris Longus flexes the wrist.
Intermediate Compartments of the Forearm
The only muscle in the intermediate compartment is Flexor Digitorum Superficialis. It is often mistaken to be in the superficial compartment of the forearm. Its primary role is for flexion of the metacarpophalangeal joints and proximal interphalangeal joints, whilst also having the ability to flex the wrist. It too is innervated by the median nerve.
Deep compartments of the Forearm
Three muscles constitute to the deep compartment of the Forearm: Flexor Digitorum Profundus; Flexor Pollicus Longus and Pronator Quadratus. Pronator Quadratus and Pollicus Longus are innervated by the median nerve. Pronator Quadratus pronates the forearm medially, whilst Pollicus Longus flexes the metacarpophalangeal and interphalangeal joint of the thumb. The Flexor Digitorum Profundus is the only muscle that is able to flex the distal interphalangeal joints of the fingers. It also flexes metacarpophalangeal joints for wrist movement. The medial side of the muscle is innervated by the ulnar nerve, whilst the lateral side of the muscle is innervated by the medial nerve.
There was no obvious damage of muscles in the anterior and posterior compartment of the upper arm, but there was obvious damage to the extensors of the wrist and flexors of the fingers in the forearm. The muscles affected were all distal to the cubital fossa. The muscles themselves were damaged, because there was little if no motor output to them.
Innervation
Nerves passing through the cubital fossa include the radial nerve and the median nerve. The ulnar nerve is neighbouring the cubital fossa, passing through the medial epicondyle. The radial nerve originates from the posterior cord of the brachial plexus and continues down the posterior part of the arm before looping around to the anterior part of the arm. It then continues downwards to the posterior compartment of the arm and to the dorsal part of the hand. The radial nerve innervates all of the muscles in the posterior compartment of the arm, including the medial and lateral heads of triceps brachii. The innervation carries on to the posterior compartment of the forearm, innervating all 12 muscles, including the extensors of the forearm and then providing sensory innervation to the dorsal part of the hand. This is directly relevant to the PBL scenario, whereby Charmilie’s wrist is hanging. Furthermore, during clinical investigation, her radially innervated muscles were unresponsive after radial nerve stimulation. The compartment syndrome has clearly damaged the radial nerve by compressing it. This has led to loss of function and input to the extensor muscles in the posterior compartment of the forearm. The extensor muscles are unable to contract and extend the wrist upwards. This is also known as radial nerve palsy. Even after treatment, her wrist remains flaccid. This entails that the radial nerve will and has not recovered. She has lost complete function of her radial nerve.
The median nerve originates from the anterior cord of the brachial plexus. From the axilla, the median nerve passes through the medial side of the arm alongside the brachial artery in between the biceps brachii and the brachialis. Initially it is lateral to the brachial artery, before anteriorly crossing over to the medial side of the brachial artery and into the cubital fossa. The main function of the median nerve is to provide motor innervation to the superficial muscles and flexors in the anterior compartment of the forearm. This includes Flexor Digitorum Profundus; Flexor Digitorum Superficialis and Flexor Pollicus Longus, but excludes Flexor Carpi Ulnaris. The scenario indicates that Charmilie is unable to make a fist. Forming a fist requires the fingers to flex. This suggests that the pressure from compartment syndrome has also damaged and compressed the median nerve, leading to lack of innervation to the finger flexor muscles. Impaired muscle innervation to Flexor Digitorum Profundus means that the distal interphalangeal joints of the index and middle finger does not function. Impaired muscle innervation to Flexor Digitorum Superficialis and Flexor Pollicus Longus, leads to inhibition to flex the proximal interphalangeal joints of the thumb and the middle finger. However, after treatment, Charmilie regains the ability to weakly flex her fingers and make a fist. This implies that the median nerve is recovering after pressure release.
The ulnar nerve starts at the anterior cord of the brachial plexus and continues down inferiorly to the humerus on the posteromedial side of the arm. It provides sensory innervation to the fourth digit, “the medial side of the fourth digit and the rest of the palm.”
Blood Supply
The anterior compartment of the upper arm receives blood supply from the brachial artery; a continuation of the axillary artery running through the axilla. The brachial artery can directly supply muscles, but can also supply some of the muscles through 3 other branches of smaller arteries. The 3 branches of arteries include [VI]:
¥ Ulnar artery – Begins just below the cubital fossa on the medial side of the arm. It runs distally along the lateral border to the wrist and crosses the carpal ligament, over the pisiform bone. It further branches to supply blood to the wrist. It can be palpated lateral to Flexor Carpi Ulnaris.
¥ Radial artery – The radial artery is a bifurcation of the brachial artery in the cubital fossa. It runs distally on the anterior part of the forearm. It can be palpated latera to Flexor Carpi Radialis
¥ Profunda brachii – Also known as the deep brachial artery. It passes distally from the Teres major, posteromedial to the brachial artery. It can be located in between the heads of the triceps muscles at the back of the upper arm, thus supplies the posterior compartment of the arm.
In this case, Charmilie still has apparent pulsation in the wrist. The radial and ulnar pulses suggest that there is not significant damage to the blood vessels running through the cubital fossa. Compartment syndrome above the cubital fossa can have a tendency to compress the arteries supplying the muscles of the forearm. If the brachial artery or its branches were compressed, there would be inadequate blood supply to the forearm, leading to dysfunction of the flexors and extensors of the wrist. Muscles will degrade and the forearm will be rendered useless. The lower arm may have to be removed in surgery.
Treatment
Patients that present with acute compartment syndrome require urgent treatment. In this case, emergency fasciotomy was carried out. “The surgeons used an antero-lateral incision to perform a fasciotomy of the anterior compartment. 200ml of blood was evacuated and within a couple of minutes of this the biceps brachii started to bleed.” The intracompartmental pressure must be relieved in the area of pain. Failure to do so can result in the loss of a limb. A study carried out suggested that if the fasciotomy was carried out before 6 hours of compartment syndrome, then there was almost complete recovery of limb function. Within 6-12 hours, only 68% of patients regained full function of their limbs. However, after 12 hours, only 8% of patients recovered fully.
The pressure caused by blood accumulation in the muscular compartment is drained, relieving tension and pressure off arteries, veins, nerves and bone, hence why Charmilie’s symptoms of pain fade shortly after treatment. The fasciotomy was also carried out in the posterior aspect of the arm. This is normally because the compartment syndrome cannot always be located accurately, so the chance of losing muscle innervation outweighs the downsides. Primary wound closure was then performed to seal up the incision straight after.