11 Peripheral Nerve Injuries Done By: Reviewed By: Nada Alouda Manar Aleid COLOR GUIDE: • Females' Notes • Males' Notes • Important • Additional Objectives 1. Brachial plexus injuries. 2. Peripheral nerve injuries: - Axillary nerve. - Musculocutaneous nerve. - Radial nerve. - Median nerve. - Ulnar nerve. 1 Peripheral Nerve Injuries (PNI): Sunderland-Classification of Peripheral Nerve Injury: Type1: Conduction block (neurapraxia) “Only myelin sheath”. Type2: Axonal injury (axonotmesis). Type3: Type2 + Endoneurium injury. Type4: Type3 + Perineurium injury. Type5: Type4 + Epineurium Complete cut of the nerve injury (neurotmesis). General Approach to a Patient with PNI or Hand Injury: History Physical Examinaon InvesJgaon Consultaon Treatment • 1. Hand dominance. • Sensory. • Nerve conducon • Physiotherapy. • Compression: 2. Occupaon (it will study (NCS). splint, give NSAIDs, affect the Tx). & modify lifestyle. • Occupaonal 3. Hobbies. • Motor. If no improvement • MRI (in space- therapy. • Main Complaint: within 3 months--> occupying lesion). 1. Sensory. • Specific tests. surgical 2. Motor. • Splint / Range of (decompression, 3. -/+ Pain. moon. nerve • HPI: transposiJon, & - Site. - Onset. - tendon transfer). Duraon. - Mechanism of injury. • Trauma or - Progression of laceraon symptoms. (emergency): nerve • Risk Factors: The repair, nerve gra, physician should make sure if it is nerve transfer and injury or not tendon transfer. (compressive): - Trauma. - Previous surgery. 2 Brachial Plexus Injuries: Basic Anatomy: • It is formed from the union of the anterior rami of the 5th, 6th, 7th, 8th cervical and 1st thoracic nerves (C5, C6, C7, C8, and T1). • The plexus is divided into Roots, Trunks, Divisions, Cords and terminal Branches. ! Classification of Brachial Plexus Injuries: • Open injuries (stab wounds or gunshot wounds): - Can be at any level (roots, trunks, divisions, etc.). - Classified into: o Supraclavicular (roots, trunks, divisions). o Infraclavicular (divisions, cords, terminal branches). • Closed injuries: - More common than open injuries. - Injury is most commonly at the roots level. - Caused by car accidents, outstretching of the shoulder like when playing sports or during difficult deliveries where the baby is pulled in emergency situations. 3 - Examination of closed injuries: Nerves are not examined; Roots are examined by examining dermatomes (sensation) and myotomes (movement). Root Dermatome Myotome Shoulder C5 Shoulder tip + lateral arm. abduction + external rotation. C6 Lateral forearm + thumb and index finger. Elbow flexion. C7 Middle finger. Wrist extension. Ring and little fingers + lower aspect of medial C8 Making a fist. forearm. T1 Upper aspect of medial forearm + medial arm. Finger crossing. Brachial Plexus Dermatome. Types of Closed Brachial Plexus Injuries: Lower brachial plexus lesion: Upper brachial plexus lesion: Erb’s palsy Klumpke’s palsy 4 Types of Closed Brachial Plexus Injuries: Closed Clinically (the patient Movements Lost Brachial Roots will have opposite to (review the Associated Injuries Plexus Injuried the normal function of previous table). Injuries the damaged nerves). - Injury to the phrenic nerve that arises from the rd th th C5: loses the 3 , 4 , and 5 cervical Upper ability to abduct - Shoulder adduction. roots, so half of the Brachial the shoulder and - Internal rotation. diaphragm will be Plexus external rotation. - Elbow extension. paralyzed. Lesion C5, C6, C6: loses the - Wrist flexion. - Adult X-ray: it will show +/- C7. ability to flex elevated hemi diaphragm. Called: Erb’s elbow. * This is called waiter’s - In children the palsy (Erb- C7: loses the tip posture. intercostals are not strong - Duchenne ability to extend enough to compensate, so Palsy) the wrist. the baby will have breathing problems (obstetric palsy). - Sympathetic nerves to the face come from a branch of the 1st thoracic nerve T1. Lower C8: loses the - If T1 is injured à loss of Brachial ability to make a sympathetic supply to the Plexus fist. face on one side à Lesion The patient will have T1: loses the ability Horner’s syndrome. C8 & T1. simian hand and to cross fingers. - Horner’s syndrome: Called: clawing of all fingers. 1. Ptosis (drooping of Klumpke’s upper eye lid). palsy “It’s about hand”. 2. Miosis (constricted pupil). 3. Anhydrosis (inability to sweat). All roots The patient is unable C5, C6, Total Palsy -- to move entire limb; -- C7, C8, & flail limb. T1. Quick Clinical Hints: 1. Upper lesion (C5, C6, C7) → Erb’s palsy and phrenic nerve symptoms. 2.Lower lesion (C8, T1) → Klumpke’s palsy and sympathetic symptoms. 3.Total lesion (C5, C6, C7, C8, T1) → flail limb and both phrenic and sympathetic symptoms. 5 Peripheral Nerve Injuries: Cause of injury/nerve Clinical Features Summary innervation Nerve Motor Sensory - To the deltoid muscle so the patient will not be able to - Isolated injuries o most commonly abduct his shoulder (30-90 ). - Loss of sensation - The patient can still initiate happen with shoulder over the skin of the abduction (action of - Loss of dislocation and lateral arm on supraspinatus). abduction and compression of the lower half of the - It also supplies teres minor sensation over nerve by crutches. deltoid. that does external rotation, the lateral arm. - Axillary Nerve - Supplies the deltoid and teres minor which is the same action of muscles. infraspinatus, so the patient can still externally rotate his arm. - Isolated injuries - Corachobrachialis and usually happen with brachialis are not important - Loss of elbow - Loss of sensation stab wounds or clinically. flexion, weak over the lateral gunshots. - Biceps: supination, and forearm and the - Supplies * Weak supination (because the loss of sensation Nerve thumb. corachobrachialis, , supinator muscle can over the lateral brachialis, and biceps compensate). forearm. Musculocutaneous muscles. * Loss of flexion of elbow joint. Deltoid atrophy and loss of Cutaneous innervation: Loss of rounded contour in axillary nerve sensation over the lateral forearm in injury musculocutaneous nerve injury 6 Peripheral Nerve Injuries (Cont.): Cause of injury/nerve Clinical Features Summary innervation Nerve Motor Sensory Saturday night palsy: - Runs in the spiral - Very high radial n. injury due to groove so injuries compression of the nerve in the Injury to the happen in humerus axilla. radial n. in the bone fractures. - It’s called like this because axilla: - - Distribution: - Loss of sensation drunk people sleep with an arm All motor and High radial n. injury: along the radial n. behind the chair that causes the sensory * Upper arm (axilla): distribution. compression. functions are supplies the triceps à - Everything is affected: elbow, lost. strong extensor of the wrist, fingers, and thumb (no elbow. extension). * Lower arm above - elbow: Humerus fracture in spiral groove with radial nerve injury: ~ Brachioradialis. Injury to the - Numbness or ~ Extensor carpi radial n. in the - Normal elbow (triceps is loss of sensation radialis longus (wrist spiral groove: supplied higher; spared). over the lateral extensor). Triceps is spared - No wrist extension (wrist three and a half - Lower radial n. injury: and everything drop). fingers to the * Forearm: else is lost. - No thumb and finger extension base of proximal 1. Sensory branch: (digits drop). phalanges sensation over the dorsally. lateral three and a Posterior interosseous nerve injury: Injury to the Radial Nerve (All roots C5, C6, C7, C8, & T1). half fingers dorsally. radial n. in the forearm to the 2. Motor branch - Stab wound in the forearm. posterior - (posterior - Elbow and wrist are normal - No sensory loss; interosseous interosseous (no wrist drop). pure motor injury. nerve: nerve): thumb and - Thumb and finger extension are Elbow, wrist, finger extension. lost. and sensation are normal. Note(s): - Most of radial n. branches are in the arm (EXTENSORS). - Most of median n. branches are in the forearm (FLEXORS). - Most of ulnar n. branches are in the hand. Sensory distribution of the Wrist drop in radial nerve radial nerve in the hand injury 7 Forearm: MUSCLES • 5 Superficial muscles: o! Pronator teres → pronation of the forearm. o Flexor carpi radialis → wrist flexion. To remember o Palmaris longus → wrist flexion. them easily o Flexor carpi ulnaris → wrist flexion. o Flexor digitorum superficialis → flexion of the proximal interphalengeal joints (PIP) so flexes the middle phalynx. • 3 Deep muscles: o Flexor digitorum profundus (FDP) à flexion of the distal interphalengeal joints. o Flexor pollicis longus (FPL). o Pronator quadratus (Pq). NERVE SUPPLY • All of these muscles are supplied by the median nerve except 1 and a half are supplied by the ulnar nerve: o Flexor carpi ulnaris. o Half of flexor digitorum profundus to the little and ring finger· - The median nerve has 2 branches: o Superficial which supplies the superficial group. o Deep (anterior interosseous nerve) which supplies the deep 2 and a half muscles; the lateral half of FDP, FPL, and Pq (PURE MOTOR). Hand: MUSCLES (intrinsic muscles) o Hypothenar: opposition of the little finger. o Thenar: opposition of thumb + adduction of the thumb (adductor pollicis). o Interossei: abduction and adduction of the fingers + MP flexion + IP extension. o Lumbricals: metacarpophalangeal (MP) flexion + interphalangeal (IP) extension. ! NERVE SUPPLY The hand has 20 muscles: o 15 supplied by the ulnar nerve: 3 hypothenar + 8 interossei (dorsal and palmar) + 2 medial lumbricals (3rd & 4th) + adductor pollicis + palmaris brevis. o 5 by the median