Neurosurgery, stroke, neurophysiology and TLOC [04/11/20]] Flashcards
What seperates the cerebral hemispheres?
Falx cerebri [dura mater]
Embryologically, what is the cerebrum derived from?
The prosencaphalon
Compare the grey and white matter function
Grey - surface each hemisphere, and is associated with processing and cognition
White - consists of glial cells and myelinated axons, connecting various areas
What are the main sulci in the brain?
Central sulcus [frontal and parietal lobes], lateral sulcus [frontal and parietal from the temporal lobes], lunate sulcus [occipital cortex]
What are the main sulci in the brain?
Precentral gyrus, postcentral gyrus, superior temporal gyri [inferior to the lateral sulcus, responsible for reception and processing sound]
Function of frontal lobe
Higher intellect, personality, mood, social conduct, language [dominant hemispehre only]
Function of parietal lobe
language and calculation dominant side, visuospatial functions [e.g. 2-point discrimination] on the non-dominant side
Function of the temporal lobe
memory and language [including where the auditory cortex lies]
What does the inferior part of the occipital cortex lie on?
Tentorium cerebelli, seperates the cerebrum from the cerebellum.
Vasculature of the brain
ACA supplying the anteromedial aspect, MCA [continuation internal carotids] supplying the lateral parts, PCA [branches of the basilar arteries] supplying both the medial and lateral sides of the cerebrum posteriorly
Describe how a CVA would present in the frontal lobe?
personality, behavioural, problem solving disability
CVA in the parietal lobe
attention deficits, contralateral neglect syndrome
CVA in the temporal lobe
Recognition dericits [e.g. auditory or prosopagnosia], occipital [contralateral hemaniopia or quadrantanopia], global deficits [severe cognitive deficits like dementia]
What are the two major functions of the meninges?
Provide supportive framework for the cerebral and cranial vasculature, act with CSF to protect the CNS from mechanical damage
Which pathways do each of these tests evoke: somatosensory EP, visual EP, TMS
SEP - sensory pathways
VEP
TMS - motor
What is a nerve?
a bundle of axons
Which neurotransmitter is at the NMJ that NCS tests?
ACh
In NCS, response is small then what, is slow then what?
Small = axonal loss Slow = myelin loss
What is the most common cause of axonal loss in the UK?
Alcohol and DM
Example of a treatable demyelinating condition?
GBS
When are EMGs used?
When myopathy and problem with muscle [not nerve problem]
How is neurotransmission dodgy in MG?
Time between contractions vary therefore this can cause a jitter
how sensitive is EMG for MG?
More sensitive than antibody tests
When are EEGs primarily done?
Primarily done for seizures
When are intra-cranial EEGs done?
Pts with focal epilepsy where medication doesn;t work
also helps ascertain where seizures come from
How are focal seizures often Dx?
Often simple observations all that is needed.
Sx of temporal vs Sx of frontal lobe seizures
Temporal = aura, behavioural arrest, automatisms Frontal = sleep dep., brief, hypermotor
What are the main uses of somatosensory evoked potentials?
MS: demyelination shows response recorded from scalp is delayed
Inappropraite monitoring e.g. spinal cord durgery; if cord compromised response gets smaller, then is lost. Aim to warn surgeon before too late.
When is TMS used?
Record contralateral muscle; can selectively look at central motor pathqway. Used for MND, MS.
Therapuetic in depression.
