Muscle and nerve diseases Flashcards
What are the common presentations of muscle disorders
- Poor suck/ feeding/ failure to thrive/ floppy
- Weakness of skeletal muscle
- Shortness of breath (respiratory muscles)
- Poor swallow (aspiration)
- Cardiomyopathy
- Cramp, pain, myoglobinuria (black pee)
- Wasting/ hypertrophy
- Normal/ reduced tone and reflexes
- Motor weakness (not sensory)
Describe the classifications of muscle disease
- Muscular dystrophies (usually genetic): something is wrong with the structure of the muscles
- Channelopathies: where something is wrong with the channel and presents with episodic weakness or rigidity
- Metabolic muscle disease (enzyme): They will have a low level of weakness normally but after exercise (long or short depends on the disease) they will feel very weak
- Inflammatory muscle disease
- Congenital myopathies
- Iatrogenic- medication (statins often cause muscle problems)
Explain (giving examples) muscular dystrophies
- If anything goes wrong with these proteins then you will have muscle problems
- Duchenne’s MD (X-linked): very few sufferers live to see adulthood
- Becker’s MD (milder form of Duchenne’s)
- Facioscapulohumeral MD (This is a category of muscular dystrophies)
- Myotonic dystrophy
- Limb-girdle MD (category of muscular dystrophy)
Explain channelopathies
- Disorders of Na, Ca and Cl channels
- Familial hypokalemic periodic paralysis
- Hyperkalemic periodic paralysis
- Paramyotonia congenita
- Myotonia congenita
- Measure the calcium (either very high or very low) associated with thyroid disease
- Myotonia will not relax (people will feel very stiff)
Explain metabolic muscular diseases
- They will have a low level of weakness normally but after exercise (long or short depends on the disease) they will feel very weak
- If potassium is very low you can present with weakness
- Disorders of carbohydrate metabolism
- Disorders of lipid metabolism
- Mitochondrial myopathies/ cytopathies
- Endocrinopathy (thyroid, adrenal)
- Biochemical abnormalities
Explain inflammatory muscular diseases
- Polymyositis: just affects the muscles
- Dermatomyositis (paraneoplastic): effects the muscle and skin
- Often autoimmune
- If someone is weak and has a rash then dermatomyositis would be high on your list
- If you have diagnosed someone with dermatomyositis then look for underlying cancer
- Acute or subacute
- Painful weak muscles
- Any age
- Other symptoms may be involved
- Investigation: raised CK, EMG, inflammation, myopathic, Biopsy (CD8 cells for PM and humoral mediated, B-cells and CD4 cells for DM)
- Treatment: immunosuppression
What are the investigations of muscle disease?
• History and examination • CK (creatinine kinase): for muscle specifically • EMG • Muscle biopsy - Structure - Biochemistry - Inflammation • Genetic testing
Describe the clinical presentation, investigation and treatment of myasthenia gravis
• Presentation: fatigable weakness
- Limbs
- Eyelids (ptosis)
- Muscles of mastication (chewing), swallow
- Talking
- SOB
- Diplopia
• Investigations
- AChR ab
- Anti-MuSK ab
- Neurophysiology: repetitive stimulation, jitter
- CT chest (thymoma)
• Treatment
- Symptomatic: acetylcholinesterase inhibitor (drugs that stop the breakdown of Ach)
- Immunosuppression: prednisolone, steroid saving agent (azathioprine)
- Immunoglobulin/ plasma exchange (get rid of the antibody)
- Thymectomy
What are the causes of peripheral neuropathy?
• Metabolic: Alcohol, Diabetes, renal, B12
• Toxic: drugs
• Hereditary
• Infectious: Lyme’s disease, HIV, leprosy
• Malignancy: paraneoplastic
• Inflammatory demyelinating
- Acute: Guillain-Barre syndrome
- Chronic: Chronic inflammatory demyelinating polyneuropathy
What are the symptoms of of pathologies that occur to the nerve at various levels?
• Nerve root - Myotomal wasting and weakness - Reflex change - Dermatomal sensory change • Individual nerve - Wasting and weakness of innervated muscle - Specific sensory change • Generalised peripheral neuropathy - Sensory and motor symptoms starting distally and moving proximally
List the clinical features of upper and lower motor neuron lesions
• Upper motor neuron - No wasting (if there is misuse of muscle then you will see some wasting later on) - Increased tone (spasticity) - Increased reflexes - Pyramidal pattern of weakness • Lower motor neurons - Decreased tone - Decreased reflexes, flexor planter - weakness
Define myelopathy and radiculopathy
- Myelopathy: spinal cord
* Radiculopathy: nerve root
List the causes of a non-compressive spinal cord lesion
• Inflammation - Demyelination (MS) - Autoimmune (antibody mediated e.g. aquaporin 4, lupus) - Sarcoid • Vascular - Ischaemic - Haemorrhage • Infective - Viral: herpes simplex/ zoster, EBV, CMV, measles, HIV etc - Bacterial: TB, borrelia (Lyme), Syphilis, Brucella - Other: Schistosomiasis • Metabolic - B12 deficiency • Malignant/ infiltrative • Congenital/ genetic - Friedreich's ataxia, spinocerebellar ataxias • Idiopathic
Describe the clinical presentation and management of motor neuron disease
• Presentation - Wasting/ fasciculation of the tongue - No sensory features - Combined UMN and LMN signs • Treatment - Supportive: PEG, NIV, physio, OT, care - Riluzole (no evidence to support that it really helps, the best study showed it gave 2 more months but there have been negative studies that haven't been published)
