Overview of Clinical Neurology Flashcards
state general facts about the brain
- The mass of the brain is 1.3KG
- The brain consists of 20 billion neurons with a similar number of glial or supporting cells
- The brain consists of grey matter and white matter.
- The corpus collusum connects left and right hemispheres and contains 300 million myelinated axons
- The fibres in the brain are crossed e.g left leg to right brain
- Language is controlled by regions in left hemisphere hence “dominant hemisphere”
describe grey matter and white matter
- The grey matter is on the outside and the white matter is on the inside.
- The grey matter is the neuronal cell bodies and the white matter is myelinated axons.
- You can only see 1/3 of the grey matter within the brain, because of gyral patterns (folds of the brain) contain 2/3 of the grey matter.
- The direction of axons is complex
- The myelinated axons are like insulated cables transmitting neural messages. If this myelin is affected or damaged e.g MS then this impairs the transmission and function depending where the demyelination occurs.
name the 5 lobes of the brain
- Frontal
- temporal
- occipital
- parietal
- Insula - The insula lies deep to the temporal lobe and it is the fifth lobe. It has five finger like projections.
describe the frontal lobe
- planning and goal directed behaviour.
- Long term planning, goals to achieve the effect.
- Extremely important, consists of 40% of the brain’s substance with the remaining lobes being 20% each.
- The infero-frontal lobe contains brocchus area- expressive speech
- Phineas G. Frontal lobe damage → behavioural changes
temporal lobe
- medial-temporal) houses the amygdala and hippocampus (memory and delivering part of the limbic or emotional system).
- Conceptual understanding and language function (semantics).
- Important hearing functions
Occipital lobe
visual cortex and has information for visual processing
Parietal lobe
is responsible for spatial awaraness and extrapersonal space
name other important structures of the brain
- Motor and Sensory strip
- Central sulcus is an important landmark
Visual information is taken to….
- visual cortex.
- Then there are 2 pathways that the information passes along, ventral stream and dorsal stream.
- These go to the temporal (what?) lobe and parietal (where?) lobe respectively.
- Due to the segregation of the pathways, a moving object can be seen but when static it cannot be seen.
discuss the dissociation between functions
Ravel is a musical composer and is a famous sufferer of fronto-temporal dementia. Some of his music pieces have a repetitive structure. Music is as complex as language with its structural and emotional overlays. Despite complete verbal output, he was still able to understand and appreciate music.
brain shrinkage due to ageing vs dementia
- a natural process of ageing
- Dementia is NOT a natural process of ageing it is pathological
semantic dementia
targets the left temporal lobe
-dominant in language so that will be affected
-relevant for concepts and conceptual understanding (of categories for e.g).
-Over time, understanding of categories is lost.
-Can understand what an animal is, but no further categories e.g bird, fish etc
what is the cause of dementia?
-due to pathological proteins being laid down and interfere with the neuronal function
-the region where the proteins are laid down is damaged and the natural shrinkage with ageing is accelerated.
-These affected regions demonstrate impaired function.
-Depending where process starts= presenting symptom.
what happens if hippocampus in medial-temporal lobe is damaged?
memory is affected
what happens if hippocampus in superior temporal lobe is damaged?
language is affected
what happens if the parietal lobe damaged?
visual impairment
describe Alzheimer’s
repeats same question and forgets recent events
Terry Pratchett.
Posterior cortical atrophy
- left parietal; Lose ability to use grammar and form sentences, arithmetic.
- Right parietal lobe is concerned with viso-spatial processing. So if lobe is dysfunctional, patient cannot localise objects accurately in space.
describe what the scan image would look like
In this image the medial-temporal lobe is demonstrated. The black areas show fluidal space and so there’s space where there shouldn’t be. The hippocampus should be bulky and filling that space.
Frontotemporal dementia
- patients present with problems in language, behaviour and emotion. It is young on-set dementia.
- Memory is OK.
- Personality changes,
- empathy loss,
- disinhibited (no filter),
- appetite change with no satiety and more inclined to have a sweet-tooth.
- Behaviour becomes more impulsive, inappropriate, irritable, utilisation behaviours (don’t have long-term awareness planning beyond what they think they need to do when they see an object, impassive/apathetic)
Diagnosing Dementia:
- Things like vision, hearing etc as can have an impact on all cognitive areas.
- Their frontal lobes: executive planning and behaviours. Are they appropriate?
- Left lobe: language, specific tasks to tease out language difficulties.
- Temporal lobe: memory and conceptual understanding
- Parietal lobe: literacy, calculation, praxis (use parts of body in sequences e.g using a screw driver)
- Right lobe, temporal: visual memory/face recognition. Parietal, visuospatial/perceptual skills.
Sudden (seconds)
If sudden is it a vascular event e.g bleed, stroke, bleed, infarct?
Sabacute (days-weeks)
- if sabacute is it inflammatory or infective. By inflammatory we mean immune mediated process e.g demyelinating affecting nerve transmission(MS, neuroinflammatory conditions).
Chronic (months)
- Chronic- slow grown tumour or degenerative condition.
