Nervous system Flashcards
what is stroke
- blood supply to brain interrupted
- ischaemia is enough to cause irreversible damage to part of the brain
- results in immediate loss of function
what is the normal metabolism and blood flow of a brain
- functioning brain depends on continuous blood supply for oxygen and glucose and remove end products metabolism
- glucose metabolism leads to conversion of ADP to ATP
- ATP is required to
1. maintain neuronal integrity
2. keep major cellular Ca2+ and Na+ outside the cells and the intracellular K+ within the cell
define transient ischemia attack (TIA)
a transient episode of neurological dysfunction caused by focal CNS ischaemia, without acute infarction
define stroke
- a neurological deficit attributed to an acute, focal injury of the CNS by a vascular cause
- cell death attributed to ischemia, based on pathological, imaging, or other objective evidence
types of stroke
hemorrhagic stroke
- blood leaks into brain tissue
ischemic stroke
- clot stops blood supply to an area of the brain
blood circulation to the brain
circle of willis
signs and symptoms of stroke
- hemiplegia
- hemisensory
- dysarthria
- clumsy hand/ataxic
- aphasia
- neglect (tactile/visual)
- gaze deviation
- homonymous hemianopia
- headache
- giddiness
- unsteady gait
- brachiafacial weakness
- drowsy/unconsciousness
what is the motor pathway
pyramidal tracts (efferent pathway)
- corticospinal tract
- corticobulbar tract
what is the sensory pathway
sensory tracts (afferent pathway)
- spinothalamic - transmits pain and temperature related sensations to cerebrum via thalamus
- posterior column - transmit touch, pressure and vibrations related sensations to the cerebral cortex of the brain
- spinocerebellar - delivers kinaesthesia or proprioception related impulses to cerebellum
symptoms of stroke mimics
Face dropping
Arm weakness
Speech difficulty
common causes for stroke mimics
- hypoglycemia
- seizures with post ictal paralysis
- migraine with aura
- hypertensive encephalopathy
- cns abscess or tumours
- drugs
- psychogenic
what is stroke mimics
- presents like acute ischemic stroke but not due to vascular cause
- account up to 21% of all stroke presentations
- exclusion of stroke mimics is essential to avoid exposure to unnecessary risk of treatment
principles of stroke management
reperfusion (ischemic stroke)
- tissue plasminogen activation
- endovascular therapy
minimising complications
- acute stroke unit
- manage ICP
- rehab
secondary prevention (focus on underlying etiology)
- identify and control risk factors
- lifestyle modification
- surgical intervention
pathophysiology of a seizure
transient occurrence of s&s due to abnormal excessive neuronal activity in the brain
neurons may be
- developmentally abnormal
- damaged from prior injury
- functioning abnormally due to change in environment
typical signs/symptoms
- loss of awareness
- abnormal movements
- abnormal sensations
most seizures self-abort after several seconds to minutes
types of seizures
partial
- simple partial seizure
- complex partial seizure
- partial with secondary generalisation
generalised
- generalised tonic clonic seizure (GTCS)
- absence
- myoclonic
seizure vs epilepsy
seizure is a single event
epilepsy is a disease with a tendency to have recurrent unprovoked seizures
which lobe of the brain is in charge of what function
frontal lobe - executive functions, thinking, planning, organising and problem solving, emotions and behavioural control, personality
motor cortex - movement
parietal lobe - perception, making sense of the world, arithmetic, spelling
sensory cortex - sensations
occipital lobe - vision
temporal lobe - memory, understanding, language
what is the local effect of low CBF
decreased oxygen
- anaerobic glycolysis -> increase lactic acid -> low pH -> impair metabolic cell function
- increase free radical production -> perioxidation of fatty acid in cell organelles and plasma membrane -> severe cell dysfunction
neuronal ischemia
- decreased ATP, increased glutamate -> Na+ and Ca2+ enter cell, K+ exit cell -> H20 and Cl- enters cell -> cerebral edema -> increase ICP
all of the above leads to decreased CBF –> cell death
which part of the circles of willis supply the anterior and middle part of the brain
Anterior cerebral artery (ACA)
Internal carotid arter (ICA)
Middle cerebral artery (MCA)
which part of the circles of willis supply the posterior part of the brain
Vertebral artery (VA) Basilar artery (BA)
what is involved in the language pathway
brocca’s area (frontal lobe) - for expressing
wernickie’s area (temporal lobe) - for receptive and understanding
auditory cortex (temporal lobe) - for hearing
mouth and throat area of motor cortex (frontal lobe) - for talking
top of basilar syndrome - basilar artery occlusion
- tetraparesis/ quadriparesis with upgoing toes
- bulbar involvement
- nystagmus
- abnormal eye movement
- doll’s negative
- small and pinpoint pupils
- coma/unconscious
- apnea/ cardiorespiratory collapse
what is penumbra
- zone of destruction not structurally dead yet
- area at risk of infarction but still salvageable
how are the neurons affected if stroke is left untreated
in 1 min, 1.9million neurons die
each hour in which treatment fails to occur, brain loses 3.6 years of normal aging worth of neurons
