Lecture 7- Upper Limb Nerve Injuries Flashcards
where do the lower motor nerve injuries arise from?
Anterior horn cell
Describe the upper motor neuron disease present?
-Held in flexed posture if chronic
-increased tone
-Pyriamidal weakness (flexor muscle stronger than extensors
-Brisk reflexes
Sensory level
Describe the lower motor neuron disease present?
- muscle wasting/fasciculations
- flaccid tone
- Weakness in either a myotomal distribution or a peripheral nerve distribution
- reduced flexes
- dermatomal or peripheral nerve distribution of sensory loss
name the three anatomical localisation of the brachial plexus?
Roots
Brachial plexus
peripheral nerve
Describe a mytome?
relationship between the spinal nerve and the muscle
Describe a dermatome?
relationship between the spinal nerve and the skin
Which myotome is responsible for bicep reflex?
C5 reflex conveyed through musculocutanoeus nerve
Which myotome is responsible for supinator jerk?
C6 reflex conveyed through the radial nerve
Which myotome is responsible for Tricep jerk?
C7 reflex conveyed through the radial nerve
Which myotome is responsible for finger jerk?
C8 reflex conveyed through the median and ulnar nerve
What happens when nerve root is impinged?
caused by slipped disc
-Causes pain which radiates
-Aggravated by neck movement
-
what protects cervical spine from injuries?
flexibility of cervical spine protects it from fractures
Describe the types of nerve (plexus) injury?
- Avulsion
- Rupture
- Neuroma
- Neurapraxia
which of the following injuries will have a worse prognosis?
Avulsion/rupture- brachial plexus trauma, neurapraxia blunt injury
What is flail arm injury caused by?
C5-T1 lesions causes flail arm
- cuases left shoulder subluxation
- Atrophy of the left deltoid
- supraspinatous and infraspinatous
What are causes the brachial plexus injury?
-Trauma:
-Erb-Duchenne type paralysis: Avulsion of C5,C6 roots.
-Klumpke paralysis: Avulsion of C8, T1 roots.
Cancer: Lung cancer: Pancoasts tumour
Radiotherapy
-Inflammatory
Brachial neuritis
- Structural:
- Thoracic outlet syndrome
What is Erbs palsy and what is caused by?
- Upper plexus palsy c5/c6 innervated muscle
- injury to the superior trunk of brachial plexus caused by blow to the shoulder
What type of muscle weakness does Erbs Palsy cause?
Biceps: flexes the arm Brachioradialis: flexes the arm in semi prone position Deltoid: abducts the arms Supraspinatous: abducts the arm Supinator: externally rotates the arm
Arm can not be:
elevated, abducted, externally rotated and is fixed at the elbow
But fingers are unimpaired- hands work but arms does not
Describe what the Klumpke’s palsy caused by?
Caused by: clutching for an object when falling from a height causes inferior trunk plexus injury involving C8/T1:
Involves trunk that supplies median and ulnar nerve
What happens to the muscles as a result of Klumpke’s palsy?
- Unable to flex wrist or fingers
- Weakness of all small muscles of the hand
- sensory loss hand and inner border of forearm
- May lead to claw hand
- Arm works but the hand does not
What is idiopathic brachial neuritis?
- Aetiology not clear, infectious/post infectious
- severe pain over days, followed by weakness and wasting
- Typically monophasic/ rarely bilateral
- MRI shows thickening and enhancement
- NCS/EMG is useful for prognostication
- Treatment: analgesia, physiotherapy
- limited evidence for the use of steriods
what is the thoracic outlet syndrome caused by?
variation in anatomy causes compression sites at following places:
1) Between anterior and middle scalene muscle
2) Beneath clavicle in the costoclavicular space
3) Beneath the tendon of pectoralis minor
Neurogenic symptoms for thoracic outlet syndrome?
- Paresthesia, numbness and weakness
- Not localised to specific nerve distribution
- reproducibly aggravated by elevation or sustained use of arms or hands
Vascular symptoms of thoracic outlet syndrome?
Vascular:
- forearm fatigue within minutes of use
- swelling and cyanosis
- collateral venous patterning over the ipsilateral shoulder, chest wall and neck
- Rarely pain,pallor and coldness
- Lower BP on affected arm, diminished distal pulses
What can cause an injury to the long thoracic nerve?
-Blows or pressure in the posterior triangle of the neck
-Can be injured during radical mastectomy
Leading winged scapula
What does the long thoracic nerve supply and what is the result of injury?
- serratus anterior
- Serratus anterior muscle pulls the medial border of the scapula to the posterior thoracic wall and stabilises it there
- Impairment of the long thoracic nerve leads to winging of the scapula
what are the two common sites of compression for the median nerve?
Wrist- carpal tunnel syndrome
-Elbow
Which muscles in the hand is innervated by the median nerve?
Remember LOAF Lateral 2 lumbricals Opponens pollicis Abductor pollicis brevis Flexor pollicis brevis
what are the causes of the carpal tunnel syndrome?
diabetes Pregnancy hypothyroidism RA repetitive strain trauma
where does the interosseous nerve arise from?
from median nerve- Just above the elbow
what causes the compression of the interosseous nerve?
compression causes by two heads of pronator teres muscle which is caused by:
- Gripping tightly with forced pronation
- prolonged use of a screwdriver
- may be damaged in careless blood taking
what is the anterior interosseous nerve syndrome?
- Pure motor branch of the median nerve
- weakness of the flexors of ip joint of the thumb (flexor pollicis longus) and dip joints of index and middle fingers (flexor digitorum profundus) causing weakness of pronation
Ulnar Vs C8
C8- all fingers extensors (radial nerve)
FDP of index/middle (median nerve)
what is known as Saturday night palsy?
Radial nerve palsy
what is the effect of the axonal loss?
results in decrease in amplitude
What is the effect of demylinating?
results in decrease in velocity
