T2 l11 Flashcards
what type of cell does lower motor neuron injuries arise from
Anterior horn cell
what is the difference between lower motor neuron and upper motor neuron injuries in the upper limb
UMN:
- Held in flexed posture if chronic.
- Increased tone
- Pyramidal weakness (Flexor muscles stronger than extensors)
- Brisk reflexes.
- Sensory level
LMN:
- Wasting/Fasciculations
- Flaccid tone
- Weakness in either a myotomal distribution or a peripheral nerve distribution
- Reduced reflexes.
- Dermatomal or peripheral nerve distribution of sensory loss.
where are the 3 anatomical regions for localising the lesions within the brachial plexus
Roots
Brachial plexus
Peripheral nerve
what do myotomes describe
Relationship between the spinal nerve & muscle
what do dermatomes describe
- Relationship between the spinal nerve & skin -is an area of the skin supplied by nerve fibres originating from a single dorsal nerve root.
what are the myotomes and muscle actions of roots c5-8 and T1
c5- deltoid-shoulder abduction
c6-Biceps, brachialis, Brachioradialis- elbow flexion
c7-Triceps, Superficial forearm extensors, superficial forearm flexors- elbow extension, wrist extension and wrist flexion
c8- Forearm extensors, deep forearm flexors- finger extension and finger flexion
T1- Intrinsic hand muscles - finger abduction -
describe some reflexes and the roots its supplied by through the named nerve
Biceps reflex – C5 reflex conveyed through the musculocutaneous nerve.
Supinator jerk – C6 reflex conveyed through the radial nerve.
Triceps jerk – C7 reflex conveyed through the radial nerve.
Finger jerk – C8 reflex conveyed through the median and ulnar nerve.
what occurs to reflexes in LMND
Reflexes are depressed
what are the causes of nerve root impingement
- Nucleus pulposus herniation into spinal canal
- pain – radiates/ aggravated by neck movement
what are the consequences of nerve root impingement
- sensory loss
- weakness
- reflex loss
What are the types of nerve plexus injuries
Avulsion: Tearing of the nerves from its attachment at the spinal cord. – Require surgical repair
Rupture: Tearing of the nerves but not from its attachment to the spinal cord – Require surgical repair
Neuroma: tumour or growth of the nerve tissue. Can arise from the axon or myeloma – Require surgical repair
Neurapraxia: Axons remain intact, but myelin damage cause an interruption of the impulse down the nerve fibre – Good prognosis.
describe motor cycle injury
Flail arm- cervical root avulsion:
C5-T1 lesions causing flail arm
Left shoulder subluxation
Atrophy of the left deltoid, supraspinatous and infraspinatous
What are the causes of 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
upper plexus palsy C5/C6 innervated muscles Superior trunk of brachial plexus (adults- blow to shoulder) Weak muscles include - Biceps (flexes the arm) Brachioradialis (flexes the arm in semi-prone position) Deltoid (abducts the arm) Supraspinatus (abducts the arm) Supinator (externally rotates the arm)
what is ‘waiters tip
rm cannot be- Elevated Abducted External rotated Flexed at elbow But fingers unimpaired Hand works but arm does not!
what is KLUMPKEs palsy
Clutching for an object when falling from a height.
- Inferior trunk plexus injury involving C8/T1
Involves trunk that supplies median and ulnar nerves
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 a claw hand
Arm works but hand
does not!-LMND
Describe metastatic branchial plexopathy
Pancoast tumour -(lung)ast tumour (lung) – infiltration of the lower brachial plexus
Pain in shoulder girdle and inner arm.
Ipsilateral horners syndrome
describe Radiation induced brachial plexopathy
Mean 6 yrs post radiation
Associated with treatment for breast, lung cancer and lymphoma
Pain is not a consistent feature
Predilection for upper brachial plexus
Describe idiopathic brachial neuritis
Parsonage – Turner Syndrome
Aetiology not clear, infectious, post-infectious
Severe pain over days; as pain diminishes, it is followed by weakness and wasting (motor>sensory)
Typically monophasic
Rarely bilateral
MRI shows thickening and enhancement.
NCS/EMG is useful for prognostication.
Treatment:
Analgesia, physiotherapy
Limited evidence for the use of steroids
describe thoracic outlet syndrome
Variations in anatomy cause compression sites:
- Between anterior and middle scalene muscles
- Beneath clavicle in the costoclarvicular space
- Beneath tendon of Pectorlis minor
what are the neurogenic symptoms of thoracic outlet syndrome
Paresthesia, numbness, weakness
Not localised to specific nerve distribution
Reproducibly aggravated by elevation or sustained use of arms or hands.
what are the vascular causes of thoracic outlet syndrome
Forearm fatigue within minutes of use.
Swelling and cynaosis
Collateral venous patterning over the ipsilateral shoulder, chest wall and neck.
Rarely pain, pallor and coldness (arterial involvement).
Lower BP on affected arm, diminished distal pulses.
learn brachial plexus slide 27
how was it
what causes a winged scapula
Long thoracic nerve may be injured by blows or pressure in the posterior triangle of the neck or during a radical mastectomy.
Long thoracic nerve supplies the serratus anterior muscle.
The 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 2 common sites of compression of the median nerve
- Wrist (Carpel tunnel syndrome)
- Elbow
what is the mneumonic for the supplies of the median nerve
L ateral 2 lumbricals
O pponens pollicis
A bductor pollicis brevis
F lexor pollicis brevis
what causes thenar wasting
median nerve compression????
learn the anatomy of the carpal tunnel
how was it
what are the causes of carpal tunnel syndrome
Causes include: Diabetes Pregnancy Hypothyroidism Rheumatoid arthritis Repetitive strain
Median N. Entrapment at Carpal Tunnel (also damaged in wrist fractures)
where does the anterior interosseous nerve arise from
median nerve just below the elbow
what is the AIN prone to
Prone to compression between 2 heads of pronator teres muscle Gripping tightly with forced pronation Prolonged use of a screwdriver! May also be damaged in careless blood taking
describe the anterior interosseous nerve syndrome
Pure motor branch of the median nerve
weakness in flexors of ip joint of thumb (flexor policis longus)
& dip joints of index and middle fingers – (flexor digitorum profundus)
weakness of pronation
what is the sensory innervation of the median nerve in the forearm versus carpal tunnel
?????????
look at picture of
Ulnar nerve palsy at the wrist
what is ulnar claw
Higher lesion in the upper limb:
Paralysis of the ulnar half of the flexor digitorum profundus (FDP), interossei and lumbricals. The ring and little fingers are not flexed and there is no claw.
Lesion at the wrist:
Flexion at the DIP (FDP is intact)
Flexion at the PIP (interossei are paralysed)
hyperextention at the MCP (lubricals are paralysed).
what can affect the sensory innervation of the ulnar nerve
lesion proximal to dorsal cutaneous branch
Lesion distal to dorsal cutaneous branch
Lesion distal to palmar cutaneous branch
Look at slide 43
how was it
what is froments sign
Weakness of adductor pollicis leads to the Froment’s sign.
what does the ulnar nerve supply vs C8
slide 45
C8
All finger extensors (radial nerve)
FDP of Index/middle (median nerve)
what is Saturday night palsy
Radial nerve palsy
describe nerve conduction studies
Useful in determining the amplitude and velocity of a peripheral nerve
difference between axonal and demyelinating differences in amplitude
Axonal loss results in a decrease in amplitude
Demyelinating results in a decrease in velocity
slide 50
neurogenic vs myogenic
Needle EMG measures the electrical activity of the muscle during voluntary contraction. The pattern of the electrical activity can help distinguish a lesion arising from the nerve (neurogenic) vs muscle (myopathic)
