Upper Limb Nerve Injury Flashcards
1
Q
Between which points in the nerve tract would cause LMN condition?
A
- anywhere between the Motor cortex in the brain to the lower motor neuron in the anterior horn of the spinal cord
2
Q
What are the different signs seen in UMN and LMN lesions?
A
Upper Motor Neuron
- Held in flexed posture if chronic.
- Increased tone
- Pyramidal weakness (Flexor muscles stronger than extensors)
- Brisk reflexes.
- a clear demarcation of sensory changes
Lower Motor Neuron
- 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.
3
Q
What are Myotomes and Dermatomes
A
- Myotomes - Relationship between the spinal nerve & muscle
- Dermatomes - Relationship between the spinal nerve & skin
4
Q
What is this an image of?
- which dermatomes are affected?
A
- Herpes Zoster
- Goes to the V1 branch of the Trigeminal Nerve (CN V)
- T4 and T5 in the rips
5
Q
What are the myotomes of C5-T1
- what are their respective muscle actions?
A
6
Q
What reflexes are associated with spinal roots C5-C8?
- what is the clinical significance?
A
- 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.
In low motor lesions the reflex is depressed
7
Q
What is a nerve Impingement and what are the causes?
- what does the result of the impingement?
A
- when a nerve is trapped/ compressed
Causes
- slipped disk/ herniation - causes nucleus pulposus to herniate into the spinal canal compression the nerves
Results in
- pain on the neck - which radiates/ aggravated by neck movement
- sensory loss
- weakness
- loss of reflexes
8
Q
What type of imaging is this and what does it show?
- what is the weighting/ plane
- what is the effect of the pathology shown?
A
- T2 weighted MRI, coronal view
- shows herniated disk C6 disk causing root nerve impingement
can cause a Cervicoradicular Myelopathy (root= radiculopathy, spinal cord=mylopathy)
- there may be no motor neuron signs at the level the root is pressing on as it exits the spinal cord
- but it’s also pressing the spinal cord so you get upper motor neuron signs below that
9
Q
What are different types of Nerve plexus injuries?
- what are their corresponding repairs?
A
- 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 causes an interruption of the impulse down the nerve fibre – Good prognosis.
- it is intact so better recovery
10
Q
What pathology is seen in this image?
- what are the consequences of this pathology to other structures?
A
- C5-T1 lesions causing flail arm
- cervical root avulsion
- Left shoulder subluxation
- Atrophy of the left deltoid, supraspinatus and infraspinatus
11
Q
What are the causes of Brachial plexus Injury?
(4 main groups)
A
- Trauma
- Erb-Duchenne type paralysis: Avulsion of C5,C6 roots.
- Klumpke paralysis: Avulsion of C8, T1 roots.
- Cancer
- Lung cancer: Pancoast’s tumour
- Radiotherapy
- Inflammatory
- Brachial neuritis
- Structural
- Thoracic outlet syndrome
12
Q
What is Erbs palsy (Erb-Duchennetype paralysis)?
- What is the cause
- what is the effect on other structures?
A
- Avulsion of C5, C6 roots
- Usually caused during parturition or as a blow to the shoulder in adults
causes weak muscles in the following
- 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)
the arm doesn’t work but the hand does
13
Q
What is Klumpke’s Palsy?
- What is the cause
- What is the effect on other structures?
A
- Inferior trunk plexus injury involving Avulsion of C8/T1
- Clutching for an object when falling from a height, at birth when pulled with the arm in a breach delivery
- 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 the forearm
- May lead to a claw hand
- Arm works but hand does not!
14
Q
What is Pancoast Tumour?
- What is the neurological effect of this tumour
- What are further implications of treating the tumour?
A
- An apical lung cancer close to the inferior brachial plexus
- the tumour can infiltrate into the lower brachial flexus
- effects the arm but the hand works
- Pain in the shoulder girdle and inner arm
- Ipsilateral horners syndrome
Can also experience radiation-induced brachial plexopathy
- experienced 6 yrs post radiation
- associated with treatment for breast, lung cancer and lymphoma
- pain is not a consistent feature
15
Q
What is radiation-induced Brachial plexopathy
A
- experienced 6 yrs post-radiation treatment
- associated with treatment for breast, lung cancer and lymphoma
- pain is not a consistent feature
16
Q
What is Ipsilateral horners syndrome?
- cause
- symptoms
A
- An interruption of nerve supply from the brain to the face and eye, on one side of the body.
- Usually caused due to injury to the spinal cord, stroke, tumour or underlying conditions.
- Symptoms: small pupils (miosis), little or no sweating on the affected side, drooping of the eyelids and unequal pupils.
17
Q
What is Idiopathic Brachial Neuritis
- cause?
- symptoms/presentation?
- investigation/ treatment?
A
- Aetiology not clear, infectious, post-infectious
- Severe pain over days; as the pain diminishes, it is followed by weakness and wasting (motor impact is >sensory)
- Typically monophasic (rarely happens again)
- Rarely bilateral
- MRI shows thickening and enhancement.
- NCS/EMG is useful for prognostication.
- Treatment:
- Analgesia, physiotherapy
- Limited evidence for the use of steroids
18
Q
What are the two presentations of Thoracic Outlet Syndrome?
- what do they result in?
A
Neurogenic: predominantly affects the median-innervated abductor pollicis brevis muscle
- results in thenar wasting
Vascular: High rib causes area of stenosis with a post stenotic dilatation.
- Clots may form in the dilated vessel with small fragments that then become detached and pass down the brachial artery into the hand. Acute ischaemic changes lead to Raynaud’s phenomenon.
19
Q
What are the anatomical variations that cause compression sites in Thoracic Outlet Syndrome?
(2)
A
- Between anterior and middle scalene muscles
- Beneath clavicle in the costoclarvicular space
- Beneath tendon of Pectorlis minor
20
Q
What is the Neurogenic presentation of Thoracic Outlet Syndrome?
(3)
A
- Paresthesia, numbness, weakness
- Not localised to specific nerve distribution
- Reproducibly aggravated by elevation or sustained use of arms or hands.
21
Q
What is the Vascular presentation of Thoracic Outlet Syndrome?
(5)
A
- 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.
22
Q
what is the supply of the long thoracic nerve?
How can the Long Thoracic Nerve be damaged?
- what pathology does this result in? and why?
- how can damage be tested
A
- blows or pressure to the posterior triangle of the neck
- damaged during a radical mastectomy
- leads to a winged scapula
- 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
- pushing against a wall causes the scapula to wing out
23
Q
What are the common sites of compression in the Median nerve?
A
- Wrist –> (carpel tunnel syndrome)
- Elbow
24
Q
LOAF
What does the Median nerve innervate in the hand?
A
- Lateral 2 lumbricals
- Opponens pollicis
- Abductor pollicis brevis
- Flexor pollicis brevis
25
What is Carpal Tunnel Syndrome?
- causes (5)
- symptoms/presentation (3)
- diagnostic tests (2)
* Median Nerve entrapment at the carpal tunnel
* can also be damaged in wrist fractures
Caused by
* Diabetes
* Pregnancy
* Hypothyroidism
* Rheumatoid arthritis
* Repetitive strain
Symptoms/ presentation
* can cause thenar waisting
* tingling in three and a half fingers,
* wake up at night to shake their hand
Diagnostic tests
* Tinel's sign - tap to reproduce symptoms
* Phalen's sign - fold-down wrist to reproduce symptoms
26
What is the common site of compression of the Interosseous Nerve?
- how else might it be damaged
(where does the nerve arise from)
arises from the median nerve just above the elbow
* 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
27
What is seen in Inrersosseous nerve syndrome?
- why are these signs seen?
* weakness in flexors of DIP (end joints of the) joint of the thumb (flexor policis longus supplied by the n.)
* weakness in _dip joints of index and middle fingers_ – (flexor digitorum profundus supplied by the n.)
* weakness of pronation
* results in a flat pinch
28
How is sensory innervation of the median nerve impacted depending on where the lesion is?
* if the lesion is more distal there is greater sensory and motor disfunction
* one of the sensory branches of the median nerve decussates earlier on
29
What are the two different motor pathologies associated with the ulnar nerve?
* Ulnar palsy at the elbow
* 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.
* Ulnar palsy at the wrist - Claw hand
* Flexion at the DIP (FDP is intact)
* Flexion at the PIP (interossei are paralysed)
* hyperextension at the MCP (lubricals are paralysed).
30
What are two key branches of the ulnar nerve and how are they clinically significant?
31
How could the Ulnar nerve be damaged?
* fractures
* compression at the Guyon's canal (at the pisiform bone)
* occupationally, cycling, rheumatoid arthritis can cause this as the nerve is so superficial
32
What sign indicates Ulnar n. palsy?
- what is the biomechanics behind this?
* Froment's sign
* Ulnar nerve supplies the Ulnar nerve abductor pollicis causes this
33
How do you distinguish between Ulnar lesion vs a C8 lesion?
motor examination exam
* C8 supplies
* all finger extensors - radial nerve so a finger extension would be effected
* Flexor Digitorum Profundus of index/ middle finger- median nerve
* Radial nerve palsy (extenders effected) - flappy wrist
* Numbness in the region of the anatomical snuffbox indicates radial nerve damage
34
What Radial Nerve pathologies are there?
- causes
* Radial nerve palsy (extenders effected) - flappy wrist
* Numbness in the region of the anatomical snuffbox indicates radial nerve damage
35
What does a nerve conduction study do?
- what two conditions can it identify
* determines the amplitude and velocity along peripheral nerve
* Demyelinating conditions- slower velocity
* Axonal loss - decrease in amplitude
36
What does a Needle EMG measure?
- what two pathologies can it distinguish between?
* 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)_
