Nerve and Muscle Flashcards
Which neurodegenerative problems are neuroglia involved in?
MS (multiple sclerosis)
ALD (adrenoleukodystrophy)
ALS (motor neurone disease)
What is a demyelinating disease?
A condition that results in damage to the myelin sheath
What are the consequences of myelin damage?
Nerve impulse slow/stop causing neurological problems
Deficiency in sensation, cognition or other functions specific to the nerve involved
Extensive myelin loss is usually followed by axonal degeneration and often cell body degeneration
How do we divide demyelinating diseases?
Divided on basis of the cause
- Demyelinating myelinoclastic diseases – secondary: healthy myelin is destroyed by a toxic (eg, alcohol), infectious agents, chemical or autoimmune substance.
- Demyelinating leukodystrophic (dysmyelinating) diseases – primary: myelin is abnormal and degenerates; caused by genetics, some idiopathic.
What is multiple sclerosis?
Common demyelinating disease of the CNS.
Aetiology – autoimmune in nature
Environmental/genetic factors lead to loss of tolerance to self proteins.
Inflammation and injury to the myelin sheath and nerve fibres
-multiple areas of scarring (sclerosis i.e. lesions/plaques).
Physical, mental, psychiatric problems
What is Lambert-Eaton syndrome?
Presynaptic - reduced Ach release
Rare autoimmune response which inhibits Ca2+ channels, so theres no influx of calcium into the channel and thereby reduced Ach release
About half patients have “small cell lung cancer”
What is its presentation, diagnosis and treatment ?
The mean age of onset ~ 60 years.
Characterized by fatigue, weakness in limb muscle groups, autonomic dysfunction, and abnormal reflexes.
Does not usually effect respiratory, facial or eye muscles.
Dry mouth
Symptoms almost always precede detection of cancer - patients rarely complain of lung issues
To diagnose: Electromyography (EMG) - apply electrical impulses to nerves and measure the electrical response of muscle
Treatment: immunosuppresant’s e.g cortcosteroids or amifampridie. This is a drug which blocks K+ channe; so action potential duration is increased, so more ACh is released.
What is myasthenia gravis - its presentation, symptoms, diagnosis and treatment?
Postsynaptic - reduced nAChR activation
Autoimmune response against nAChR’s - NMJ less responsive to ACh
Disease is characterised by a decrease in number of AChR
As there are fewer AChR to bind, the end plate potentials (EPPs) are smaller
There is less chance a post-synaptic muscle fibre will be activated
Symptoms: muscle weakness and fatigue
Two forms: effects extraocular muscles, generalised muscle weakness
Repetitive stimulation leads to decrease contractile strength weakness greatest at the end of the day or after exertion
Diagnosis: Lab findings, MRI or CT for possible thymoma, antibodies to ACh receptor, electromyography test, edrophonium or neostigmine test
Treatment: anticholinesterase, immunosuppression and some patients have tumour of the thymus which if removed, leads to improvement
Genetic muscle disorder?
Muscular dystrophy
3 neurological muscle disorders?
Multiple sclerosis, myasthenia gravis, Parkinson’s disease
What is Wolff Parkinson White syndrome?
one of several disorders of the conduction system of the heart that are commonly referred to as pre-excitation syndromes. WPW is caused by the presence of an abnormal accessory electrical conduction pathway between the atria and the ventricles. Electrical signals travelling down this abnormal pathway (known as the bundle of Kent) may stimulate the ventricles to contract prematurely, resulting in a unique type of supraventricular tachycardia referred to as an atrioventricular reciprocating tachycardia.
Use of digitalis / fox glove
To treat heart conditions as it decreases heart rate
What are the causes, symptoms and presentation of dilated cardiomyopathy?
Sudden death
Heart enlarges, functions poorly
Muscle becomes weak, inefficient causing fluid build up in the lungs, → breathlessness → left heart failure
Right heart failure → fluid build up in tissues & organs (legs, ankles, liver, abdomen)
Symptoms: shortness of breath, swelling of the ankles, tiredness, palpitations and syncope and chest pain
Causes: viral infections, auto-immune disease, excessive alcohol consumption/exposure to toxic compounds, pregnancy, familial disease
What are the causes, symptoms and presentation of hypertrophic cardiomyopathy?
Thickening of muscle; may thicken in normal individuals as a result of high blood pressure or prolonged athletic training.
HCM -thickening without obvious cause.
Frequently asymptomatic until cardiac death
Normal alignment of muscle cells is absent myocardial disarray
More common in young adults
Prognosis variable - many stable for years
Symptoms: shortness of breath, chest pain, palpitation, light headedness and black outs
Causes: genetic mutation of proteins involved in heart contraction
Example of a smooth muscle disorder
Leiomyoma (fibroids) Benign growth Female reproductive tract Usually multiple, diameter 5mm upwards More prevalent approaching menopause Heavy uterine bleeding &/or pain Cause unknown, associated factors include genetic factors More common in Afro-Caribbean race
