Neurology - Intro Flashcards
Neural layers of the brain
Skull Extradural space Dura mater Subdural space Arachnoid Pia mater Blood/Brain barrier [sep CSF + Blood]
Blood-Brain barrier
Endothelial cell of capillaries overlap
Protected by astrocytes
Allows only oxygen + nutrient exchange
Neural damaging agents
Anoxia Hypoglycaemia Viral infection Metabolic disturbance Brain is susceptible to oxygen + glucose reduction - no storage tissue
Neural Damage
2 Types:
Necrosis [assoc with acute function failure]
Atrophic [assoc with gradual function loss]
Retrograde degeneration
Secondary neural damage
Main axon damage - degen of neuron as well as classical distal degen of axon
Trans-synaptic degeneration
Secondary neural damage in closely integrated neuron systems
Neuron loss followed by degen of assoc neurons across synapses
Satelitosis
Chromatolysis resutls increase in number of oligodendrocytes after damage of neurons
Gliosis
Damage results in cells multiply + enlarging + increase in fibril production
Cells atrophy - leads to function reduction
Consequence of nerve damage
Primary: -destruction of myelin -precedes axon damage Secondary: -loss of nerve cells + axon destruction
Pathological mechanism of Cerebral Oedema
- Initiating disorder = Cytotoxic components [cellular injury to neuron + glia]
- Vasogenic components = capillary permeability leaks protein
Raised Intracranial pressure
-expanding leasion [haeme + infarct]
-obstruction of CSF flow
Will lead to pupil dilation ipsilateral to mass/lesion
Cushing’s Triad
Hallmark signs of increased ICP [opposite of shock]
- increased systolic BP
- reduced pulse
- reduced respiration
Stages of ICP increase due to expanding lesions
- Compensation
- Decompensation
- Vasomotor paralysis
Secondary complications:
= Vascular damage [compres CRV - papilledema]
= Nerve pressure [N3 + N6][sudden oculomotor paralysis]
= CSF flow obstruction
= Skull bone changes if prolonged
Cerebral Hypoxia
BP below 50 mmHg
Fast + permanent damage [Necrosis within 5min]
Cerebral Infarction [stroke] pathogenesis
Precipitation condition - perfusion failure - infarction [ischaemic necrosis]
Haematoma - def
accumulation of blood outside of vessel