5- Neurology (Less acute: Brain tumours and stroke) Flashcards
presentation of brain tumours
- Often asymptomatic when small
- Focal neurological symptoms depending on location of lesion
- RICP
investigation for brain tumour
Investigations
- MRI
- CT
Papilloedema
Papilloedema is a swelling of the optic disc secondary to raised intracranial pressure. Papill-refers to a small rounded raised area (the optic disc) and -oedema refers to the swelling. The sheath around the optic nerve is connected with the subarachnoid space. Therefore it is possible for CSF under high pressure to flow into the optic nerve sheath. This increases the pressure around the optic nerve where it connects with the back of the eye at the optic disc, causing optic disc swelling. This can be seen on fundoscopy examination.
Fundoscopic Changes
- Blurring of the optic disc margin
- Elevated optic disc (look for the way the retinal vessels flow across the disc to see the elevation)
- Loss of venous pulsation
- Engorged retinal veins
- Haemorrhages around optic disc
- Paton’s lines which are creases in the retina around the optic disc
Pituitary Tumours
Pituitary tumours tend to be benign. If they grow large enough they can press on the optic chiasm causing a specific visual field defect called a bitemporal hemianopia. This causes loss of the outer half of the visual fields in both eyes. They have the potential to cause hormone deficiencies (hypopituitarism) or to release excessive hormones leading to:
* Acromegaly
* Hyperprolactinaemia
* Cushing’s disease
* Thyrotoxicosis
stroke definition
a neurological deficit attributed to an acute focal injury of the central nervous system (CNS) by a vascular cause, including cerebral infarction, intracerebral hemorrhage (ICH), and subarachnoid haemorrhage (SAH)”
also known as a cerebrovascular accident (CVA)
Cerebrovascular accidents are either:
Ischaemia or infarction of brain tissue secondary to inadequate blood supply
Intracranial haemorrhage
Disruption of blood supply can be caused by:
- Thrombus formation or embolus, for example in patients with atrial fibrillation
- Atherosclerosis
- Shock
- Vasculitis
Transient ischaemic attack (TIA)
was originally defined as symptoms of a stroke that resolve within 24 hours. It has been updated based on advanced imaging to now be defined as transient neurological dysfunction secondary to ischaemia without infarction.
Transient ischaemic attacks often precede a full stroke.
A crescendo TIA is where…
is where there are two or more TIAs within a week. This carries a high risk of developing in to a stroke.
presentation of stroke
suddent onset neurological symptoms
* Sudden weakness of limbs
* Sudden facial weakness
* Sudden onset dysphasia (speech disturbance)
* Sudden onset visual or sensory loss
Risk Factors of stroke
Cardiovascular disease such as angina, myocardial infarction and peripheral vascular disease
Previous stroke or TIA
Atrial fibrillation
Carotid artery disease
Hypertension
Diabetes
Smoking
Vasculitis
Thrombophilia
Combined contraceptive pill
FAST Tool for Identifying a Stroke in the Community
F – Face
A – Arm
S – Speech
T – Time (act fast and call 999)
management of stroke
- Admit patients to a specialist stroke centre
- Exclude hypoglycaemia
- Immediate CT brain to exclude primary intracerebral haemorrhage
- Aspirin 300mg stat (after the CT) and continued for 2 weeks
Options if ischaemic stroke - must exclude risk of intracranial haemorrhage
- Thrombolysis
- Thrombectomy
Thrombolysis with
Alteplase can be used after the CT brain scan has excluded an intracranial haemorrhage.
- Alteplase is a tissue plasminogen activator that rapidly breaks down clots and can reverse the effects of a stroke if given in time.
- It is given based on local protocols by an experienced physician.
- It needs to be given within a defined window of opportunity (4.5 hours)
- Patients need monitoring for post thrombolysis complications such as intracranial or systemic haemorrhage.
- This includes using repeated CT scans of the brain.
strict rules associated with alteplase
Clinical diagnosis of ischemic stroke causing neurological deficit
Time of symptom onset <4.5 hours
> 18
the parietal lobe
Location Posterior to central sulcus
Major functions
1) Sensory
2) Comprehension of speech (usually left hemisphere)
- Wernicke’s area
3) Body image (usually right)
4) Awareness of external environment (attention)
- Condition called Neglect – despite the fact pt has normal visual field, they can’t acknowledge the existent of one of half of their environment
5) Calculation and writing
6) Don’t forget visual pathways projecting through white matter
- Superior optic radiations pass through the parietal lobe
the temporal lobe
LocationInferior to sylvian fissures
Major functions
1) Sensory (relatively posterior)
- Hearing- primary auditory cortex (superior)
- Olfaction- primary olfactory cortex (inferior)
2) Memory
- Hippocampus sits deep in the temporal love e.g. factual memory
3)Emotion
- Thought olfactory centre (smell) is linked to emotional function
4) Don’t forget visual pathways projecting through white matter
- Inferior optic radiations pass through the temporal lobe
The corpus callosum
Allows the left and right hemispheres to work together
A huge bundle of white matter connecting the two hemispheres. An early surgical treatment for severe epilepsy was to cut the corpus callosum to prevent seizure activity from propagating through the whole brain. This had some interesting neuropsychological consequences for those patients…
Brocas area
- Inferior lateral portion (think face of homunculus) of frontal lobe
- Production of speech (motor function)
- Directs muscles to produce language
Wernickes area
- Superior portion of temporal (some say parietal as well) lobe - near primary auditory region
- Interpretation of language (sensory)
- Understanding of what is being said
Brocas and Wernickes areas are connected together via
Arcuate fasciculus (green)- white matter
- Best though of as a unidirectional pathway (although is technically bilateral)
1) Pathway for repeating a heard word
- Word heard
- Auditory info is processed in the cortex within the primary auditory cortex and then goes to Wernicke’s area- where it is interpreted and translated into language
- Wernicke’s area then communicates with Broca’s’ area through the arcuate fasciculus
- Broca’s area tells the cortex to produce pattern of muscle contractions which will produce the sound of the word that was previously heard
- Impulse to primary motor cortex (PMC) area which drives the facial and laryngeal muscles, resulting in repetition of heard word
Damage specially to arcuate fasciculus results in patients not being able to repeat the word
2) Pathway for speaking a written word
- When we read we use primary visual cortex in occipital lobe
- Visual pattern sent from visual cortex to Wernicke’s area
- Wernicke’s is then able to examine pattern as impulses and interpret pattern as a word
- Wernicke’s then sends word via the arcuate fasciculus to Broca’s area
- Broca’s area then instructs PMC to produce a pattern of muscular contraction in order to produce pattern of musculature contraction to produce the read word
3) Pathway for speaking a thought
- Thoughts can arise from many brain regions, but converges at Wernicke’s area
- Wernicke’s interprets thought patterns and converts into language
- Sends impulses to Broca’s via the arcuate fasciculus
- Broca’s sends to PMC instructing to produce pattern of musculature contraction to be able to speak thought
