Muscle and Nerve Diseases Flashcards
(126 cards)
1
Q
Examples of muscles and nerve diseases; disorders of….
A
Muscle
NMJ
Peripheral nerve
Anterior horn cell
2
Q
What does NMJ stand for?
A
Neuromuscular junction
3
Q
Definition of a muscle
A
An intricate machine designed to convert chemical energy to mechanical energy
4
Q
Presentation of muscle disease
A
Poor suck / feeding / failure to thrive / floppy Weakness of skeletal muscle SOB (resp muscles) Poor swallow (aspiration) Cardiomyopathy Cramp, pain, myoglobulinuria Wasting / hypertrophy of muscle Normal or reduced tone or reflexes Motor weakness
5
Q
Definition of myoglobulinuria
A
Peeing black urine after exercise
6
Q
Do you get sensory weakness in muscle disease?
A
NO
7
Q
Classification of muscle diseases
A
Muscle dystrophies Channelopathies Metabolic muscle disease Inflammatory muscle disease Congential myopathies Iatrogenic - medication
8
Q
How do most people get muscular dystrophies?
A
Genetic
9
Q
What pattern of symptoms do you get with channelopathies?
A
Episodic symptoms
- completely fine, then an episodes and then back to completely fine
10
Q
Types of muscular dystrophies
A
Duchenne's MD Becker's MD Facioscapulohumeral MD Myotonic dystrophy Limb Girdle MD
11
Q
What happens in both duchennes and beckers MD?
A
Hypertrophy of the muscles
Infiltration of fat
Trouble of standing to sitting
12
Q
Presentation of facioscapulohumeral MD
A
Facial weakness
Biceps
One other upper limb and lower limb proximal weakness
13
Q
What can go wrong to cause muscle channelopathies?
A
Disorders of channels
- Ca
- Na
- Cl
14
Q
What is the most common muscle channelopathy?
A
Familial hypokalaemia periodic paralysis
15
Q
Types of muscle channelopathies
A
Familial hypokalaemia periodic paralysis
Hyperkalaemic periodic paralysis
Paramyotonia congenita
Myotonia congenita
16
Q
In muscle channelopathies when they are having an episode and are weak, what is the key thing to measure? Why?
A
Potassium
Shows organic disease
17
Q
Presentation of myotonia congenita
A
Bit of weakness
Muscles cannot relax after contract muscle - therefore feel very stiff
18
Q
Types of metabolic muscle disease
A
Disorders of carbohydrate metabolism Disorders of lipid metabolism Mitochondrial myopathies/cytopathies Endocrinopathy Biochemical abnormalities
19
Q
How does disorders of carbohydrate metabolism present?
A
Low level weakness with much more marked weakness on exercise
20
Q
Give an example of an endocrinopathy condition that can give you muscle problems and how it does so
A
Cushings
- adrenal (production of steriods) causing the weakness - a steriod induced myopathy
21
Q
What biochemical abnormality can give you muscle weakness?
A
Low potassium
22
Q
What molecule is used for immediate rapid muscle activity e.g. sprinting?
A
Glucose
23
Q
What is used up when muscles are used?
A
Energy
24
Q
Examples of inflammatory muscle diseases
A
Polymyositis
Dermatomyositis
25
What does polymyositis affect?
ONLY muscles
26
What does dermatomyositis affect?
Skin
| Muscles
27
What type of disorder, apart from inflammatory, is dermatomyositis?
Paraneoplastic
28
Presentation of inflammatory muscle disease
Painful weak muscles
Muscles sore to touch
If DM - characteristic rash
Feeling generally unwell
29
What age can get inflammatory muscle disease?
Any age
30
What is the characteristic rash of dermatomyositis?
Rash around eyes and knuckles
31
If a patient presents with painful weak muscles and a rash around eyes/knuckles, what should be done?
Look for an underlying tumour
32
Investigations of inflammatory muscle disease
Increased CK
EMG
Muscle biopsy
33
What would be find on biopsy in polymyositis?
CD8 cells
34
What would be found on biopsy in dermatomyositis?
Humeral mediated, B cells and CD4 cells
35
Treatment of inflammatory muscle diseases
Steriods
| If dont work then a steriod suppressing immunosuppressant
36
When is CK in the blood elevated?
When there is a muscle disorder
37
Investigation of muscle diseases
```
History and exam
CK
EMG
Muscle biopsy
Genetic testing
```
38
What does the muscle biopsy look for?
Structure
Biochemistry
Inflammation
39
Give an example of a disorder of the NMJ
Myastenia gravis
40
Presentation of myastenia gravis
Fatiguable weakness
- eyelids (ptosis)
- proximal muscle weakness (face, neck, limbs)
- muscles of mastication (chewing, swallowing)
- talking
- SOB
- Diplopia
- dysphagia
41
Investigation of myastenia gravis
Single fibre electromyography
AChR ab (85 - 90%)
Anti MuSK ab (40%)
Neurophysiology (repetitive stimulation, jitter)
CT chest (thymoma)
Tensilon test; IV edrophonium reduces muscle weakness temporarily (not commonly used anymore due to risk of cardiac arrhythmia)
42
Treatment of myastenia gravis
Symptomatic - long acting acetylcholinesterase inhibitor e.g. pyridostigmine
Prednisolone or a steriod saving agent (to immunosuppress originally)
Thymectomy
43
Example of a steriod saving immunosuppresant
Azathioprine
44
How does an Ach Inhibitor give symptomatic relief in myastenia gravis?
Blocks the breakdown of Ach do have more of it at your endplate
45
How does immunoglobulin / plasma exchange work in myastenia gravis?
Immunoglobulin binds to the antibody and stops it binding to the NMJ
46
What does fatiguable weakness mean?
As you use the muscle, it is strong then gets weaker
| Therefore muscles are fine in the morning but develop weakness later on in the day
47
Pathology of myastenia gravis
Anti AChR antibody blocks AchR so there is no muscle contraction
Flooded with ACh to outcompete this antibody but as the muscle fatigues it cannot do this as well
48
Where is the anterior horn cell found?
Between the UMN and LMN
49
What type of neurones are present in the LMN / PNS?
Both motor and sensory
50
What does peripheral nerve disease consist of?
Sensory axons
| Autonomic nervous system
51
Types of sensory axons
Small fibres
| Large fibres
52
What do small sensory fibres carry?
Pain
| Temperature
53
What do large sensory fibres carry?
Joint position sense and vibration
54
Example of root disease
Degenerative spine disease
55
Examples of a lesion of an individual peripheral nerve
Compressive/entrapment neuropathy (entrapment e.g. carpal tunnel syndrome)
Vasculitis (mononeuritis multiplex) - if multiple nerves affected due to if blood vessels become inflamed/enlarged
56
Where does generalised peripheral neuropathy tend to present first?
Feet THEN hands
57
Presentation of generalised peripheal neuropathy
Motor
Sensory
Both
+/- autonomic features
58
Causes of generalized peripheral neuropathy
```
Metabolic
- DM
- alcohol
- renal
- B12
Toxic - drugs
Hereditary
Infectious
- Lymes
- HIV
- leprosy
Malignancy
Inflammatory demyelinating
- Acute - GBS
- chronic - chronic inflammatory demyelinating polynueropathy
```
59
What does GBS stand for?
Guillian Barre syndrome
60
Presentation of a nerve root disorder
Myotomal wasting and weakness
Reflex change
Dermatomal sensory change
61
Presentation of disorder of an individual nerve
Wasting and weakness of innervated muscle
| Specific sensory change
62
Presentation of generalised peripheral neuropathy
Sensory and motor symptoms starting distally and moving proximally
63
Investigations of peripheral neuropathy
```
Blood tests
- vit B 12 deficiency
- LFTs
Genetic analysis (only if clear FH)
Nerve conduction studies
LP
Nerve biopsy
```
64
Why do we tend to avoid nerve biopsies?
As could leave someone with a deficit
65
Presentation of MND
Combination of UMN and LMN signs
- UMN = increased tone, brisk reflexes, spasticity
- LMN = muscle fasiculations, wasting, weakness
No sensory involvement
66
Is there sensory involvement in MND?
No
67
Prognosis of MND
Die 2 - 5 years from symptom onset
| Die 2 - 3 years from diagnosis
68
What % of patients die within 14 months of their diagnosis?
50%
69
What is usually the cause of death in MND?
Respiratory failure
70
Investigations of MND
Presentation - the unique combination of UMN and LMN signs
| EMG
71
Treatment of MND
```
Supportive
- PEG
- NIV
- Physio / OT / care
Riluzole
```
72
How does riluzole work?
Anti glutamate antagonist - blocks the action of glutamate
| Usually used in amyotrophic lateral sclerosis
73
Effects of riluzole on MND
Prolongs survival by a few months
| N.B. some trials say it does nothing
74
Types of MND
Amyotrophic lateral sclerosis (50%)
Primary lateral sclerosis
Progressive muscle atrophy
Progressive bulbar palsy
75
Clues that would point towards a diagnosis of MND
Fasciculations
Absence of sensory symptoms
Mixture of UMN and LMN signs
Wasting of small hand muscles / tibialis anterior is common
76
Other common features of MND
Does NOT affect the external ocular muscles
NO cerebellar signs
Abdominal reflexes are usually preserved and sphincter dysfunction if present is a late feature
77
Features of amyotrophic lateral sclerosis
Typically LMN signs in the arms and UMN signs in the legs
78
What is the genetic abnormality in inherited amyotrophic lateral sclerosis?
Superoxide dismutase - on chromosome 21
79
Features of primary lateral sclerosis
UMN signs only
80
Features of progressive muscle atrophy
LMN signs only
| Affects distal muscles before proximal
81
What type of MND carries the best prognosis?
Progressive muscle atrophy
82
Features of progressive bulbar palsy
Palsy of tongue, muscles of chewing/swallowing and facial muscles due to loss of function of brainstem motor nuclei
83
What MND type carries the worst prognosis?
Progressive bulbar palsy
84
Age of onset Beckers vs Duchennes
Duchennes - onset < 5 y/o
| Beckers - onset > 10 y/o
85
Which of beckers and duchennes has LD?
Duchennes
86
Which of beckers and duchennes are associated with dilated cardiomyopathy?
Duchennes
87
Treatment for restless leg syndrome
Ropinirole
88
CK level in myasthesia gravis
Normal
89
Management of myasthenic crisis
Plasmapheresis
| IV immunoglobulins
90
When does myotonic dystrophy occur?
20 - 30 y/o
91
What types of muscle does myotonic dystrophy affect?
Skeletal
Cardiac
Smooth
92
Two main types of myotonic dystrophy
DM1
| DM2
93
Inheritance of myotonic dystrophy
Autosomal Dominant
94
Genetics of each type of Myotonic dystrophy
DM1 - CTG repeat at the end of DMPK gene on chromosome 19
| DM2 - repeat expansion of the ZNF9 gene on chromosome 3
95
Main differences between DM1 and DM2
DM1 - distal weakness more prominent
| DM2 - proximal weakness more prominent, and severe congenital form NOT seen
96
Presentation of myotonic dystrophy
```
Myotonic facies (long "'haggard" appearance)
Frontal balding
Bilateral ptosis
Cataracts
Dysarthria
Myotonia
Weakness of limbs - distal initially
Mild mental impairment
DM
Testicular atrophy
Cardiac involvement - heart block, cardiomyopathy
Dysphagia
```
97
What is Eaton-Lambert syndrome associated with?
Small cell lung cancer
Ovarian cancer
Breast cancer
May also occur independently as an autoimmune disorder
98
Pathology of Eaton Lambert syndrome
Antibody directed against presynaptic voltage gated calcium channel in the PNS
99
Presentation of Eaton Lambert syndrome
```
Repeated muscle contractions lead to an increase in muscle strength (only seen in 50%)
Limb girdle weakness (affects LLs first)
Hyporeflexia
Autonomic symptoms
- dry mouth
- impotence
- difficulty micturating
```
100
Investigations of Eaton Lambert syndrome
EMG
| - incremental response to electrical stimulation
101
Treatment of Eaton Lambert syndrome
Treatment of underlying cancer
Immunosuppression (e.g. with pred or azathioprine)
IV immunoglobulins and plasma exchange
102
MRC power scores
0 - no muscle movement
1 - trace of contraction
2 - movement at the joint with gravity eliminated
3 - Movement against gravity, but not against added resistance
4 - movement against external resistance with reduced strength
5 - Normal strength
103
What MRC power score indicates that the muscle can only work with gravity removed?
2
104
Involvement of T1 in erbs palsy may result in what?
Horners syndrome
105
Damage to the ulnar nerve results in what?
Wasting of hypothenar muscles
Loss of thumb adduction
Wasting of 1st webspace
Ulnar claw hand (hyperextension at metacarpal phalangeal joint, flexion at interphalangeal joint)
106
What does the straight leg test test for?
Radiculopathy
107
What would radial nerve palsy result in?
Wrist drop
| Loss of sensation from 1st dorsal web space
108
What does musculocutaneous nerve palsy result in?
Reduced flexion at elbow
| Loss of supination
109
What does median nerve compression result in?
Carpal tunnel syndrome
110
What does axillary nerve palsy result in?
Wastage of deltoid muscles
| Loss of sensation in the badge area
111
Lesions where will cause problems with finger abduction?
T1
112
What does a +ve hoffmans sign indicate?
UMN lesion
113
Treatment for ocular myasthenia gravis
Pyridostigmine
114
What is mononeuritis multiplex?
A simultaneous or sequential involvement of individual non contiguous nerve trunks
115
Presentation of mononeuritis multiplex
```
Acute or subacute loss of sensory and motor function of individual nerves
Asymmetric
As disease progresses
- confluent
- symmetrical
```
116
What is mononeuritis multiplex hard to differentiate from as the disease becomes more advanced?
Polyneuropathy
117
What suggests GBS?
Progressive peripheral polyneuropathy with hyporeflexia
118
What is Saturday night palsy?
Compression of the radial nerve against the humeral shaft. Results in unable to extend wrist
Possibly due to sleeping on a hard chair with hand draped over the back
119
What is internuclear opthalmoplegia?
Occurs due to a lesion of the median longitudinal fasiculus, tract that allows to conjugate eye movements.
120
What does internuclear opthalmoplegia result in?
Impairment of adduction of ipsilateral eye
| The contralateral eye abducts, however with nystagmus
121
Causes of internuclear opthalmoplegia
MS
| Vascular disease
122
What are common precipitators of myasthenia crisis?
Beta blockers
123
Treatment of myasthenia crisis
Plasmaphresis and IV immunoglobulin
124
What does hoovers sign differentiate between?
Between organic and non organic leg weakness
125
What is the Jendrassik manouvre?
Compares a reflex with/without distraction e.g. clenching teeth
126
What does a positive rhombergs test indicate?
Sensory ataxia
