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What is MS?
- unknown (autoimmune and genetic component)
Pathogenesis of MS
- - focal damage to myelinate axons in the CNS
- - results in altered neurotransmission
- -results in altered function
At what level does MS occur?
- white matter of the periventricular region, brain stem, cerebellum, spinal cord and optic nerve
NB: myelin = white matter in the CNS
What are the clinical features of MS?
- - multiple sites of damage (at least two)
- - progressive course, with remissions/ exacerbations
- - plaques in the white matter (broken myelin, immune cells, fibrosis)
What are the signs and symptoms of MS?
- - lack of any specific signs, each case is different depending on where the plaque is
- Visual field- optic nerve or optic tract
- speech andswallowing - corticospinal tracts
- Gait, coordination and balance- cerebellum
- Extraocular mm- pons
- Position and vibration sense; paresthesia (PNS) - dorsal or posterior columns of the spinal cord
What is parkinson's disease?
- - progressive neurodegenerative disorder affecting extrapyramidal system
What is extrapyramidal system and how it works?
- Is a neural network that is part of the motor system that causes involuntary reflexex and movement, and modulation of movement. It is called the extrapyramidal to distinguish it from the tracts of the motor cortex that reach their target through the pyramids of the medulla
What is a result of parkinson disease?
- - loss of dopaminergic neurons in the substantia nigra
- - this plays an important role in movement, rewards and addiciton
Parkinson disease image
- Substantia nigra
- parkinson disease
What is the cause of parkinsons disease?
- idiopathic and secondary (encephalitis, trauma, vascular disorders)
What is the athogenesis of parkinsons disease?
- - degeneration of DA neurons in SN
- - Deficit of DA release in the striatum
- - loss of excitatory/inhibitory balance in basal ganglia circuity
- - results in mm tremor, elevated mm tone and hypokinesia (deminished motor function)
What are the signs of parkinsons disease?
- - resting tremor (disappears with voluntary movements)
- - mm rigidity
- - difficult initiating movement
- - slow movements (bradykinesia)
- - postural instability
- - dementia at later stages
What is ALS or Lou Gehrig's disease?
- - upper and lower motor neuron disease
- is a disease of the nerve cells in the brain and spinal cord that control voluntary muscle movement.
- Cause is unkown
What is the pathogenesis of lou gehrig's disease
- - gradual generalised death of motor neurons both UMN and LMN
- - combination of UMN and LMN
combination of UMN and LMN symptoms
What are the clinical features of the ALS?
- - 3 sites of damage: spinal motorneurons, brainstem motor neurons and cortical UMN
- - mm atrophy (amyotrophy)
- - loss of fibers in lateral columns of spinal cord (pyramid tract) and fibrillary gliosis (lateral scerosis)
- - starts from weakness and mm atrophy in distal parts of one arm
- - progresses to all four extremities
- - at later stages- affect swalloing and respiration
- - but sensory functions and intellect are fully preserved
What is myastenia gravis
- -autoimmune neuromuscular disease leading to fluctuating muscle weakness and fatiguability.
- Cause is unkown
What iis the pathogenesis of myastenia gravis?
- - autoimmune disorder
- - igG autoantibodies against mm ACh receptor
- - neuromuscular trasmission reduced or block
Progression- facial and oculomoator mm affected first. This is followe by limb and body mm and finally respiratory mm
- - clinical signs- think about the pathophysiology: when there is a poor transmission in the neuromuscular junction
- -mm weakness and fatigue
- - diplopia and ptosis (droopy eyes); monotonous speech
- - lack of facial expressivity (sadness mask)
- - later chewing and swallowing altered
- - weakness and fatigue in arms and legs
- - respiratory dysfunctions
- Test- tensolin (edrophonium chloride- inhibitor)
- - complication - respiratory infrection
- - treatment- antcholinesterase drugs (increase ACh action)
- - glucocorticoids (supress immunity)