Central Nervous System Flashcards Preview

Pathology > Central Nervous System > Flashcards

Flashcards in Central Nervous System Deck (62)
1

Functions of the nervous system

Basic : Sensory → Motor
(mediated by central and peripheral nervous system, autonomic and somatic)

Higher :
Consciousness
Complex and learned motor skills
Memory and planning
Communication/language

2

Brain

Cerebral hemispheres
Grey matter
White matter
Basal ganglia
Ventricular system
Brain stem
Cerebellum

3

Meninges

Membranous coverings of the central nervous system
Protective function and important in production of cerebrospinal fluid
Dura reflected from underlying surface of arachnoid, including tumour (meningioma).

4

Blood vessels - arteries

The cerebral arteries supply a defined territory within the cerebral cortex

If blood supply to a particular part of the brain is interrupted, the patient will develop symptoms due to lack of function of the part of the brain supplied by that vessel

5

The skull

The skull is a bony box which cannot expand
If the volume of tissue or fluid inside the skull increases the intracranial pressure rises
This results in herniation where a part of the brain moves from one compartment of the skull to another

6

Basic Neuroanatomy

Spinal and cranial nerves
Branches of above linking CNS to peripheral sensory receptors and effector organs (muscles & glands)
Autonomic and somatic nervous systems

7

Neuro Cells

Neurons - the processors
Glial cells - supporting functions
- Schwann cells astrocytes & oligodendrocytes

8

Speech and Language

Broca’s area
- Frontal lobe, anterior to pre-motor cortex
- Predominantly responsible for speech production

Wernicke’s area
- Temporal lobe, posterior to auditory cortex
- Speech processing and comprehension of written and spoken language

9

Frontal lobe

Complex executive functions involved in decision making; Emotional reactions: Formation of some types of memory; Motor cortex; Olfactory function; Generation of fluent speech

10

Parietal lobe

Sensory cortex and processing of sensory information

11

Temporal lobe

Language functions including auditory cortex and comprehension of written and spoken words; Memory

12

Occipital lobe

Visual cortex

13

Brain stem

Conduction of major motor and sensory pathways; Control of cardiorespiratory function and consciousness; Cranial nerve roots

14

Cerebellum

Precise motor control; ?Others – language, attention (not yet well defined)

15

Spinal cord nerve roots

Specific spinal nerves innervate defined motor functions and sensory territories
Damage to spinal cord at a specific level will cause loss of function of spinal nerves below that level

16

Focal neurological signs

a set of symptoms or signs in which causation can be localized to an anatomic site in the central nervous system

17

Generalised neurological abnormality

Essentially an alteration in level of consciousness

18

Clinical application

People who have regular contact with patients are often more likely to notice subtle changes in neurological parameters allowing prompt investigation and treatment
Basic neurological examination often allows localisation of lesion/injury in a patient with focal neurology
Imaging is usually required to confirm and better characterise the nature of the pathological process
Identification of the likely site by examination can assist in the precise radiological identification of a lesion
Assessment of consciousness allows identification of progression of a neurological insult

19

focal neurological signs - frontal lobe

Anosmia
Inappropriate emotions
Expressive dysphasia
Motor impairment

20

focal neurological signs - parietal lobe

Receptive dysphasia
Sensory impairment

21

focal neurological signs - temporal lobe

Cortical deafness
Receptive dysphasia

22

Spinal cord leisons

Physical examination helps to identify the level of injury in spinal cord lesions
Signs limited to a single dermatome or nerve root suggest either a focal nerve root injury or injury to a peripheral nerve
Signs affecting several nerve roots below a certain level eg. Complete paralysis of body and legs with maintained head and neck movement is caused by injuries to the cervical spine (usually traumatic)

23

diffuse neurological injury

Usually manifest as impairment of consciousness
Most often due to  intracranial pressure (ICP)
May occur as a primary process or as a secondary to response to a focal injury

24

Causes of reduced consciousness

May be obvious on external examination (eg. Trauma) or easily identified on basic observations (eg. Hypoxia, hypothermia)
May require additional bedside tests or more clinical history (eg. Hypo/ hyperglycaemia, post-ictal state in an epileptic patient)

25

CEREBROVASCULAR DISEASE

Leading cause of mortality and morbidity
Incorporates strokes, TIAs, intracerebral haemorrhage
2 main pathological processes
Hypoxia, ischaemia and infarction due to impaired blood supply/oxygenation
Haemorrhage from CNS vessels
Brain requires constant supply of glucose and oxygen
Brain accounts for 1-2% body weight but receives 15% resting cardiac output and accounts for 20% blood oxygen consumption
Cerebral blood flow is autoregulated to maintain adequate perfusion over a wide range of blood pressure and ICP

26

Blood flow reduced to a portion of the brain, tissue survival depends on :

Collateral circulation
Duration of ischaemia
Magnitude and rapidity of flow reduction
Blood flow reduced to the whole brain ie. Global hypoperfusion (eg hypotension, cardiac arrest) can result in generalised neuronal dysfunction

27

F A S T

Face- facial drooping
Arms- person may not be able to raise both arms and keep them raised due to weakness or numbness
Speech- slurred speech
Time- is of the essence ring for ambulance urgently

28

Stroke or Transient Ischaemic Attack

TIAs are characterised by temporary loss of function that resolves itself within 24 hours
Sometimes called “mini-strokes”
Symptoms are similar to that of a full stroke but recovery is rapid

29

Treatment of TIA's

1 in 10 chance of having a full stroke within 4 weeks if left untreated
Anti-platelet therapy: aspirin or clopidogrel
Control blood pressure
Lower cholesterol

30

Stroke

Loss of function lasting greater than 24 hours

2 main pathological types:

Ischaemic

Haemorrhagic

31

Stroke risk factors

Hypertension
Diabetes mellitus
Heart disease – ischaemic, atrial fibrillation
Previous transient ischaemic attacks
Hyperlipidaemia

32

Stroke causes

Hypoxia of brain
Blockage of blood vessel by atheroma
Blockage of blood vessel by embolus

Bleed into the brain
Hypertension related
Berry aneurysm

33

Left MCA territory infarct

Damage to speech area in Left hemisphere -> loss of speech (aphasia)
Damage to L visual pathway-> Loss of vision to Right (Hemianopia)
Damage to left motor cortex and internal capsule -> Weakness of Right face, arm and leg

34

Management of Stroke patients

NICE guidance
Thrombolysis
Aspirin/Clopidogrel
Physiotherapy
Occupational therapy
SALT
Supportive treatment

35

causes of haemorrhagic events

Hypertension
Vascular malformation
Berry aneurysm
Neoplasia
Trauma
Drug abuse
Iatrogenic

36

intracerebral haemorrhage

‘Haemorrhagic stroke’
Presents as headache, with rapid or gradual decrease in conscious level – localizes depending on site of bleed
Usually arterial in origin
Show mass effect
In 80% of cases with hypertension bleed is ‘capsular haemorrhage’
Few survive

37

subarachnoid haemorrhage

Spontaneous
Often catastrophic
80% rupture of saccular aneurysms
‘Thunderclap headache’
‘Meningitis like’ signs
Requires neurosurgical input

38

subdural haemorrhage

Fluctuant conscious level
Often on anticoagulants
Bleeding from bridging veins between cortex and venous sinuses
Blood between dura and arachnoid
Often minor trauma in the elderly

39

extradural haemorrhage

Post head injury, slowly falling conscious level, possibly with lucid period
Often with fractured temporal or parietal bone
Typically the middle meningeal artery

40

Dementia

Progressive and largely irreversible clinical syndrome with widespread impairment of mental function.

Complex needs and high levels of dependency and morbidity

People should have chance to make decisions about their care in conjunction with the medical teams

41

Dementia presentation

80,000 people in the UK
> 65 years old increased risk
Memory loss
Speed of thought
Language
Understanding/Judgement
People can become disinterested in usual activities
Have difficulties in controlling emotions

42

Patterns of dysfunction frontal

Disorders of behavior
Mood
Motivation
Judgment
Planning
Reasoning
Appetite and continence
Disinhibition

43

Patterns of dysfunction temporal

Memory dysfunction

44

Patterns of dysfunction Parietal

Dysphasia and dyspraxia

45

Patterns of dysfunction subcortical

Slowness of thought processes

46

Dementia assessment

Can include
TSH – ensure thyroid function is normal
CT scan (Not all cases) to check for intracranial pathology
Vitamin B12, thiamine – alcoholism

47

Alzheimer's Disease

Due to an accumulation of Aβ amyloid, Tau – neurofibrillary tangles and plaques, and loss of neurones and synapses
Leads to defects of visual-spatial skill (gets lost), memory loss, decreasing cognition, ansognosia (lack of awareness)

48

Alzheimer's Disease Treatment

Needs multidisciplinary team approach

New treatments include cholinesterase inhibitors eg rivastigmine

Their use is closely controlled by NICE

49

Epilepsy

A recurrent tendency to spontaneous, intermittent, abnormal electrical activity in part of the brain, manifest as seizures’
Seizures can take many forms
Focal twitching, trance-like, convulsions
Usually no identified cause
For example, can be due to
Space occupying lesions
Stroke
Alcohol withdrawal

50

Epilepsy diagnosis

Good history taking
Exclude structural abnormality
EEG
Any triggers?

51

Epilepsy management

Compliance is very important
Depending on seizure type
Have serious side effects, eg teratogenic
Examples
Sodium valproate – epilim
Carbamazepine
Phenytoin
Lamotragine

52

Meningitis

Bacterial
Neisseria meningitidis
Pneumococcus
Meningococcus
Viral
Fungal

53

Meningitis presentation

Early
Headache
Cold hands and feet
Pyrexial
Late
Neck stiffness
Photophobia
Kernig’s sign
Non-blanching rash
Seizures

54

Brain Abscess

Focal infection
Can lead to focal brain damage or mass effect
Can present with headaches, seizures, temperature
Radiologically a ‘ring enhancing lesion’ – differential diagnosis is a glioblastoma
Can spread via blood, eg.
Embolus from bacterial endocarditis
IV drug users at risk
Or direct, eg.
From an infected inner ear

55

Parkinson's disease

Movement disorder
Sporadic or familial
Occurs 1 in 1000, usually over 50 years
Can be drug induced

56

Parkinson's disease presentation

rigidity
bradykinesis
resting tremor
postural instability
Postural instability due to the progressive degeneration of the dopaminergic nigrostriatal system and other neuronal networks.

57

Parkinson's disease treatment

MDT approach
L-dopa eg Madopar
Anticholinergic drugs eg orphenadrine

Drug induced Parkinson’s (eg Haloperidol) can be helped by procyclidine

58

TUMOURS/SPACE OCCUYPING LESIONS

Benign tumours can cause problems depending on location and mass effects

Can affect the skull, the meninges or the brain itself

59

TUMOURS/SPACE OCCUYPING LESIONS presentation

Headaches
Seizures
Cognitive or behavioral change
Vomiting
Altered conciousness

60

Meningiomas

Benign tumours
Generally well circumscribed, slow growing
Derived from meningothelial cells
Enlarge slowly, don’t often infiltrate the brain, and can be often be removed surgically
Can be found incidentally on brain imaging scans

61

Astrocytomas

Range from WHO Grade I-IV

Grade I generally good outcome, grade 4 usually fatal

62

Pituitary tumours

Cause compression symptoms
For example of the optic nerve
These can be hormonally active
Classified based on the hormone produced
For example a prolactinoma
Surgically removed transphenoidally