Session 9 Flashcards
(20 cards)
What arteries supply the brain?
Paired internal carotid and vertebral arteries
Describe the route and branches of the internal carotid artery
Originates at the bifurcation of the common carotid arteries (C4). They move within the carotid sheath, and enter the brain via the carotid canal. They do not supply any branches to the face or neck. They pass anteriorly through the cavernous sinus then gives rise to: ophthalmic artery (orbit), posterior communicating artery (connecting vessel in the Circle of Willis) and the anterior cerebral artery (cerebrum). They then become the middle cerebral arteries (lateral cerebrum).
Describe the route and branches of the vertebral arteries
They arise from the subclavian arteries then ascend up through the transverse processes of the cervical vertebrae (foramen transversarium). They enter the cranial cavity via the foramen magnum. Within the cranial vault they give off: Meningeal branch (falx cerebelli), anterior and posterior spinal arteries (spinal cord, spanning its entire length). and posterior inferior cerebellar artery (cerebellum).
The two vertebral arteries then converge to form the basilar artery.
What do the pontine arteries supply?
Corticospinal tracts (locked in syndrome)
What are the two communicating arteries in the circle of Willis and where do they connect?
Anterior communicating artery - connects the two antererior cerebral arteries
Posterior communicating arteries - connects the middle cerebral arteries to the posterior cerebral arteries
What regions of the cerebrum do each of the 3 cerebral arteries supply?
Anterior - anteromedial portion of the cerebrum (area of the legs) and anterior part of corpus callosum
Middle - majority of the lateral part of the brain (area of the arms/face), internal capsule and macular cortex
Posterior - the medial and lateral parts of the posterior cerebrum
Describe the branches of the middle cerebral arteries
Continue laterally and gives rise to superior travelling lenticulostriate arteries (basal ganglia and internal capsule)
What supplies the thalamus?
A branch off the posterior cerebral artery
What vessels supply the brainstem?
Cerebellar arteries as they pass over the brainstem
Define seizure
A sudden irregular discharge of electrical activity in the brain causing a physical manifestation such as sensory disturbance, unconsciousness or convulsions
Define convulsion
Uncontrolled shaking movements due to rapid and repeated contraction of muscles
Define aura
A perceptual disturbance experienced by some prior to a seizure (e.g. light, bad smell, confusion)
What is epilepsy?
A neurological disorder marked by recurrent episodes of sensory disturbance, LOC or convulsions that are associated with abnormal electrical activity in the brain
What is status epilepticus?
Epileptic seizures occuring continuously without recovery of consciousness (usually >5 mins)
What are the commonest causes of partial seizures?
Temporal lobe epilepsy - auditory hallucinations, rush of memories, olfactory hallucinations. Mostly presents in 1st/2nd decade
Frontal lobe epilepsy - can present with abnormal movements when motor fibres affected (contralateral side)
Parietal lobe seizures - may affect the somatosensory system
What investigations are available for people with new onset seizures?
EEG - supports diagnosis. Can involve photic stimulation and hyperventilation.
MRI
ECG
What are differential diagnoses for epilepsy?
Stroke, TIA, meningitis, intracerebral haemorrhage, SLE, thyroid dysfunction, hypoglycaemia, alcohol withdrawl, intracerebral mass
What are the rules regarding driving with epilepsy?
If suffers epilepsy when awake, licence is taken away until 1 year seizure free. If due to medication change; 1 year seizure free. One off seizure; 6 months seizure free.
What are the causes of epilepsy?
Idiopathic, cerebral vascular disease, brain tumour, trauma, alcohol
What are precipitants of epilepsy?
Sensory stimuli, brain disease/trauma, hypo-glycaemia/calcaemia/natraemia, infections
