Muscle and Nerve Disease Flashcards
Muscle
An intricate machine designedd to convert chemical energy into mechanical energy
What are components of the process that sees muscles converting chemical energy to mechanical?
- Excitation-contraction coupling
- The contractile mechanism
- Structural components
- The energy system
What are symptoms of muscle disease?
- Poor suck/ feeding/ failure to thrive/ floppy
- Weakness of skeletal muscles
- Short of breath
- Poor swallow
- Cardiomyopathy
- Cramp/ pain/ myoglobinuria
What are the signs of muscle disease?
- Wasting/ hypertrophy
- Normal or reduce tone and reflexes
- Motor weakness (not sensory)
What investigations are there for muscle disease?
- History and examination
- Creatinine kinase
- EMG
- Muscle biopsy (structure, biochemistry, inflammation)
- Genetic testing
What are the classifications of muscle disease?
- Muscular dystrophies
- Channelopathies
- Metabolic muscle disease
- Inflammatory muscle disease
- Congenital myopathies
- Iatrogenic
What do muscular dystrophies affect?
The mechanics of the muscle and are usually genetic
Give examples of muscular dystrophies.
- Duchenne’s MD
- Becker’s MD
- Facioscapulohumeral MD
- Myotonic dystrophy
- Limb-Girdle MD
What does facioscapulohumeral MD tend to present with?
Facial, scapula and bicep weakness
Who is normally affected by Duchenne’s MD?
Boys
What is abnormal in Duchenne’s MD?
Dystrophin
What are channelopathies disorders of?
Ca, Na and Cl channels
Give 4 examples of channelopathies.
- Familial hypokalemic periodic paralysis
- Hyperkalemic periodic paralysis
- Paramyotonia congenital
- Myotonia congeniita
What are metabolic muscle diseases?
Disorders of carbohydrate and/or lipid metabolism
Give examples of metabolic muscle diseases
- Mitochondrial myopathies/cytopathies
- Endocrinopathy (thyroid, Cushings)
- Biochemical abnormalities
Give examples of inflammatory muscle diseases.
- Polymyositis
- Dermatomyositis
What does polymyositis affect?
The muscles
What does dermatomyositis affect?
Muscle and skin
When can inflammatory muscle diseases occur?
At any age
Other than painful weak muscles, how can dermatomyositis present?
Characteristic rash
What do polymositis and dermatomyositis result in?
Painful weak muscles
What is the treatment for inflammatory muscle disease?
Immunosuppression
What investigations should be carried out for inflammatory muscle disease?
-Creatinine kinase (will be increased)
-EMG, inflammation and myopathic
Biopsy
What will be found on muscle biopsy in polymyositis?
CD8 cells
What will be found on muscle biopsy of dermatomyositis?
Humeral mediated B cells and CD4 cells
Give an example of a disorder of the NMJ.
Myasthenia gravis
What is the clinical presentation of myasthenia gravis?
Fatiguable weakness of:
- Limbs
- Eyelids
- Muscles of mastication (chewing) and swallow
- Talking
- SOB
- Diplopia
What are the investigations for myasthenia gravis?
- AChR ab
- Anti MuSK ab
- Neurophysiology (repetitive stimulation and jitter)
- CT chest (thymoma)
What symptomatic treatment for myasthenia gravis is there?
Acetylcholinesterase inhibitor
What immunosuppression treatment is there for myasthenia gravis?
- Prednisolone
- Steroid saving agent azathioprine
When is immunoglobulin/plasma exchange used as treatment in myasthenia gravis?
In critically ill patients who are struggling to breath. It is a temporary measure
What surgical procedure is often performed on those with myasthenia gravis?
Thymectomy
What do peripheral nerves consist of?
- Sensory axons
- Motor axons
What do small sensory fibres carry?
Pain and temperature
What do large sensory fibres carry?
Joint position sense and vibration
Give examples of nerve root diseases.
- Degenerative spine disease
- Inflammation
- Infiltration
What are the types of lesions of individual peripheral nerves?
- Compressive/ entrapment neuropathy
- Vasculitic (mononeuritis multiplex)
How can generalised peripheral neuropathy present?
- Motor/ sensory or both
- +/- autonomic features
What are the causes of generalised peripheral neuropathy?
- Metabolic: diabetes, alcohol, renal failure, B12
- Toxic: drugs
- Hereditary
- Infectious: Lyme, HIV, leprosy
- Malignancy: paraneoplastic
- Inflammatory demylineating
What is an examples of an acute inflammatory demyelinating condition?
Guillain Barre syndrome
What is an examples of a chronic inflammatory demyelinating condition?
Chronic inflammatory demyelinating polyneuropathy
What are the signs and symptoms of nerve root disease?
- Myotomal wasting and weakness
- Reflex change
- Dermatomal sensory change
What are the signs and symptoms of individual nerve disease?
- Wasting and weakness of innervated muscle
- Specific sensory change
What are the signs and symptoms of generalised peripheral neuropathy?
Sensory and motor symptoms starting distally and moving proximally
What investigations should be carried out for nerve disease?
- Blood tests
- Genetic analysis
- Nerve conduction studies
- Lumbar puncture with CSF analysis
- Nerve biopsy (nb sensory nerve)
How does ALS progress?
- Usually limb onset
- Later bulbar and respiratory involvement
What LMN signs are there in ALS?
- Muscle fasciculations
- Wasting
- Weakness
What UMN signs are there in ALS?
- Increased tone
- Brisk reflexes
What is the prognosis for ALS?
- 3-5 years from symptom onset
- 2-3 years from diagnosis
- 50% will die within 14 months of diagnosis
How is a diagnosis of motor neurone disease made?
- Unique combination of UMN and LMN signs
- EMG
What is the treatment for motor neurone disease?
- Supportive (PEG, NIV, physio, OT, care)
- Riluzole
