Vasculature and Circle of Willis

Question 1

How is a stroke defined?

Answer 1

Stroke is defined by the World Health Organizationas a clinical syndrome consisting of ‘rapidly developing clinical signs of focal (at times global) disturbance of cerebral function, lasting more than 24 h or leading to death with no apparent cause other than that of vascular origin’.

Question 2

What are the symptoms of stroke?

Answer 2

Symptoms of stroke include numbness, weakness or paralysis, slurred speech, blurred vision, confusion and severe headache.

Question 3

What is a TIA?

Answer 3

A transient ischaemic attack (TIA) is defined as stroke symptoms and signs that resolve within 24hours. The symptoms of a TIA usually resolve within minutes or a few hours at most, and anyone with continuing neurological signs when first assessed should be assumed to have had a stroke.

Question 4

what is a non-disabling stroke?

Answer 4

A non-disabling stroke is defined as a stroke with symptoms that last for more than 24hours but later resolve, leaving no permanent disability.

Question 5

What is an Ischaemic stroke?

Answer 5

MC type 80+%
Thrombotic – Large vessel/small vessel

TIA

Embolic

Hypo perfusion

Question 6

What is a haemorrhagic stroke?

Answer 6

Intracerebral haemorrhage

Subarachnoid haemorrhage

Question 7

What are the 5 D’s 3 N’s & A ?

Answer 7

5D’s
Dizziness
Diplopia, blurred vision or transient hemianopia
Drop attacks (loss of power or consciousness)
Dysphagia (problems swallowing)
Dysarthria (problems speaking)

3 N’s
Nystagmus
Nausea or vomiting
Other neurological symptoms

5 others
Light headiness or fainting
Disorientation or anxiety
Disturbances in the ears - tinnitus
Pallor, tremors, sweating
Fascial paraesthesia or anaesthesia.

Question 8

What is the internal carotid artery?

Answer 8

Branch of common carotid artery

Passes through carotid canal of skull  curves forward within cavernous sinus  through dura  divide into anterior and middle cerebral arteries

Question 9

What is the vertebral artery?

Answer 9

Branch of subclavian artery
Vertebral arteries from each side join  basilar artery  circle of Willis  posterior cerebral artery

Principle artery to brain stem, cerebellum, occipital lobe and thalamus

Question 10

Who discovered the circle of Willis?

Answer 10

Thomas Willis 1621-1675
Royal physician to Charles I
Discoverer of the blood supply of the brain

Question 11

What is the anterior cerebral artery?

Answer 11

Passes superiorly over optic chiasm  joined to its counterpart by anterior communicating artery  branches over medial surface of hemisphere to about level of parieto-occipital sulcus

Question 12

What is the middle cerebral artery?

Answer 12

Larger of two terminal branches of internal carotid

Supplies insular cortex, frontal, parietal and temporal lobes

Question 13

What is the posterior cerebral artery?

Answer 13

At pons-midbrain junction basilar artery > posterior cerebral artery > laterally anterior to root of oculomotor nerve > wraps around midbrain > anterior and medial surfaces of temporal lobes

Supplies midbrain, thalamus, ventral and medial surfaces of temporal and occipital lobes as far as the parieto-occipital sulcus

Question 14

What is Hemineglect?

Answer 14

Following damage the non dominant hemisphere, a deficit in attention to and awareness of one side of the field of vision can be observed.

Question 15

What are the sinus’ of the head/brain?

Answer 15

Superior Sagittal Sinus
Between falx and inside of skull

Inferior Sagittal Sinus
In free edge of falx cerebri

Straight Sinus
In seam between falx and tentorium cerebelli

Transverse Sinuses
Between tentorium and its attachment to skull

Sigmoid Sinuses
S-curved continuations of transverse sinuses

Sphenoparietal Sinuses
Drain deep middle cerebral veins

Question 16

Within the brain substance is a communicating system of cavities that are lined with what?

Answer 16

Within the brain substance is a communicating system of cavities that are lined with ependyma forming the choroid plexus and filled with cerebrospinal fluid (CSF)

Question 17

What is the Cerebral Aqueduct Of Silvius?

Answer 17

A narrow, curved channel running from the posterior part of the third ventricle into the fourth ventricle
It contains no choroid plexus

Question 18

What is the secretion of CSF?

Answer 18

CSF is secreted by choroidal epithelial cells of choroid plexuses

400-500ml of CSF is secreted daily by the choroid plexuses. CSF is a colorless acellular fluid that flows through the ventricules into the subarachnoid space.

Choroid plexuses consist of vascular fringes of pia mater covered by cuboidal epithelial cells

Choroid plexuses found in roof of 3rd and 4th ventricles, and on the floor of body and inferior horns of lateral ventricles

Question 19

What is The circulation of CSF?

Answer 19

Lateral ventricles >interventricular foramina > 3rd ventricle >cerebral aqueduct > 4th ventricle >median and lateral apertures > subarachnoid space, which is continuous around spinal cord and posterosuperiorly over cerebellum > subarachnoid cisterns > superiorly through sulci and fissures on medial and superolateral surfaces of cerebral hemispheres; and to extensions of subarachnoid space around cranial nerves > arachnoid granulations > dural venous sinuses

Question 20

What is the function of CSF?

Answer 20

Supports and protects the central nervous system from concussive injury
Transports hormones and hormone-releasing factors
Removes metabolic waste products through absorption