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
Subarachnoid haemorrhage
Caused by aneurysm at circle of Willis
If spreads leads to gen edema
Delayed complication of head injury
Haemorrhages from extradural haematoma
With time haematoma increases - increase ICP
Dura strips away from skull
Subdural Haematoma
results from rupture of bridging veins between arachnoid + dura [loosely connected]
Intracerebral Haematoma
Increase ICP - cerebral hypoxia
May lead to external leakage of CSF + Blood [ear + nose - potential entry for infection]
Hydrocephalus
Increase CSF + dilated ventricles Mechanism: - Overproduction of CSF -CSF flow obstruction [can't reach subarachnoid space - ventricle swelling] -Defective absorption of CSF
Intracranial Headaches
Only certain tissues are pain sensitive [stretching]
- tumours causing stretching
- assoc arterial dilatation [fevers, intoxication, hypertension]
- meningeal inflamm + haemorrhage
Extracranial Headaches
All tissues are pain sensitive + nerve transference is common
- Any Inflammatory disease
- Prolonged muscle contraction
- Vascular distention [migraine = episodic vasoconstriction with dilation]
Cluster Headache
Visual origin [squinting from uncompensated refractive error]
Dull ache= frontal + temporal
assoc with lacrimation
Tension Headache
assoc with eye strain
stabbing headache with prolonged muscle contraction [neck + shoulders]
Epilepsy
Grand mal = 1% [induced by flashing lights + stress]
Petit mal [10 min or less]
Cranial Nerves
On Occasion Our Trusty Truck Acts Funny, Very Good Vehicle Any How
Olfactory Optic Oculomotor Trochlear Trigeminal Abducens Facial Vestibulochochlear Glossopharynx Vagus Accessory Hypoglossal
Meningitis
Bacterial infection
Stiff neck [excruciating pain]
Fever
Photophopia + headache
Encephalitis
Viral - Rabies, HSV, Polio, measles, VZV
Inner centre of brain affected
Variant Creutzfeld-Jacob [VCJ]
Prion = cause
Degenerative neurological disorder
Corneal transplant = possible mode of infection
Horner syndrome
Triad = Ptosis, Miosis,Anhidrosis
Disruption of ANS innervation of cervical ganglion at apex of lung
Multiple Sclerosis
Females 20 to 40
Affects Optic nerve + Cranials
Neuro-transmission affected
Diplopia + Optic neuritis + cortical blindness
Ataxia
Lack of muscle coordination
Affects speech,walking, swallow + eye movements
Tourettes - proprioception feature
Closing of eye leads to complete loss of balance
Myesthenia Gravis
Auto immune neuro muscular disorder
Block ACh
Ptosis with squint
Peripheral Neuropathy
Damage to peripheral nerves
Diabetes + Bells
Visual aura
possible feature of migraine
Distinguish from Scotoma [VF]
Cortical Blindness
total or partial loss of vision in normal looking eye
Primary visual cortex damage
Possible bilat post strokes
Visual agnosis
loss of ability to recognize objects
Lesion to visual cortex
Central achromatopsia
Colour agnosia = no ID but can match
Alexia
Brain disorder = can read letters but not words
Distruction of left visual cortex, radiations + geniculate body
Foveal Hyperplasia
underdevelopment of the macula associated with albinism
charles bonnet syndrome [CBS]
common condition among people who have lost their sight
causes people who have lost a lot of vision to see things that aren’t really there, known as visual hallucinations
