Stroke/Brain Aneurism Flashcards
Vertebrobasilar insufficiency (VBI) is
The posterior circulation supplies blood to the medulla, cerebellum, pons, midbrain, thalamus, and occipital cortex (responsible for vision). Therefore, the symptoms due to VBI vary according to which portions of the brain experience significantly decreased blood flow (see image of brain [1]). In the United States, 25% of strokes and transient ischemic attacks occur in the vertebrobasilar distribution. These must be separated from strokes arising from the anterior circulation, which involves the carotid arteries.
VBI symptoms
Vertigo,
The vertigo due to VBI can be brought on by head turning, which could occlude the contralateral vertebral artery and result in decreased blood flow to the brain if the contralateral artery is occluded.
When the vertigo is accompanied by double vision (diplopia), graying of vision, and blurred vision, patients often go to the optometrist or ophthalmologist
. If the VBI progresses, there may be weakness of the quadriceps and, to the patient, this is felt as a buckling of the knees. The patient may suddenly become weak at the knee and crumple (often referred to as a “drop attack”). Such a fall can lead to significant head and orthopedic injury, especially in the elderly.
Transient Ischaemic Attack (TIA)
A transient ischaemic attack (TIA) is an acute episode of temporary neurologic dysfunction that typically has the following characteristics[1]
lasts less than an hour (often less than 30 minutes)
results from focal cerebral, spinal cord, or retinal ischaemia
is not associated with acute tissue infarction
Amaurosis fugax (painless, temporary loss of vision)
One-sided facial droop
One-sided motor weakness
Diplopia (double vision)
Problems with balance and spatial orientation
Symptoms such as unilateral weakness, amaurosis fugax, and double vision have higher odds of representing TIA compared to memory loss, headache, and blurred vision.[
Mechanism of Injury / Pathological Process (TIA)
Like ischaemic strokes, TIAs are due to locally decreased blood flow to the brain, causing focal neurological symptoms. Decreased blood flow results from either embolism into a cerebral supply artery (from the heart, or the great proximal vessels, extracranial or intracranial arteries, usually affected by atherosclerosis), or in situ occlusion of small perforating arteries.
Resolution of symptoms probably occurs by spontaneous lysis or distal passage of the occluding thrombus or embolus, or by compensation through collateral circulation restoring perfusion into the ischaemic brain area.
Age (TIA)?
The incidence of TIAs increases with age, from 1-3 cases per 100,000 in those younger than 35 years to as many as 1500 cases per 100,000 in those older than 85 years[
Steoke is?
Stroke is defined as an accident to the brain with “rapidly developing clinical signs of focal or global disturbance to cerebral function, with symptoms lasting 24 hours or longer, or leading to death, with no apparent cause other than of vascular origin and includes cerebral infarction, intracerebral hemorrhage, and subarachnoid hemorrhage”
Ischaemic strokes are the most common, accounting for up to 80% of strokes, and occur when there is an occlusion of a blood vessel impairing the flow of blood to the brain.
Ischaemic Strokes are divided into:
Thrombotic - Where a blood clot forms in a main brain artery or within the small blood vessels deep inside the brain. The clot usually forms around atherosclerotic plaques.
Embolic - A blood clot, air bubble or fat globule forms within a blood vessel elsewhere in the body and is carried to the brain.
Systemic Hypoprofusion - A general decrease in blood supply, eg. in shock.
Venous Thrombosis - Cerebral venous sinus thrombosis (CVST) is the presence of a blood clot in the dural venous sinuses, which drain blood from the brain. Symptoms may include headache, abnormal vision, any of the symptoms of stroke such as weakness of the face and limbs on one side of the body, and seizures.
An ischemic stroke is typically caused by blockage of a blood vessel, though there are also less common causes.
Haemorrhagic Strokes occur when a blood vessel in the brain ruptures and bleeds. -
Intracerebral Haemorrhagic Stroke — there is bleeding from a blood vessel within the brain. High blood pressure is the main cause of intracerebral haemorrhagic stroke.
Subarachnoid Haemorrhagic Stroke — there is bleeding from a blood vessel between the surface of the brain and the arachnoid tissues that cover the brain.
Nb. Some experts do not classify Subarachnoid Haemorrhage as Stroke because subarachnoid haemorrhages present differently from Ischaemic Strokes and Intracerebral Haemorrhagic Strokes
A hemorrhagic stroke is caused by either bleeding directly into the brain or into the space between the brain’s membranes.[11][14] Bleeding may occur due to a ruptured brain aneurysm.
Who’s at risk for VBI?
smoking hypertension (high blood pressure) diabetes obesity being over the age of 50 family history of the disease elevated levels of lipids (fats) in the blood, also known as hyperlipidemia
Increased risk of stroke/TIA?
Hypertension
High cholesterol
Diabetes mellitus
Atrial fibrillation
Risk factors for stroke?
The main risk factor for stroke is high blood pressure.[6] Other risk factors include tobacco smoking, obesity, high blood cholesterol, diabetes mellitus, a previous TIA, and atrial fibrillation.
Stroke symptoms
If the area of the brain affected includes one of the three prominent central nervous system pathways—the spinothalamic tract, corticospinal tract, and the dorsal column–medial lemniscus pathway, symptoms may include:
hemiplegia and muscle weakness of the face
numbness
reduction in sensory or vibratory sensation
initial flaccidity (reduced muscle tone), replaced by spasticity (increased muscle tone), excessive reflexes, and obligatory synergies.[36]
In most cases, the symptoms affect only one side of the body (unilateral). Depending on the part of the brain affected, the defect in the brain is usually on the opposite side of the body. However, since these pathways also travel in the spinal cord and any lesion there can also produce these symptoms, the presence of any one of these symptoms does not necessarily indicate a stroke. In addition to the above CNS pathways, the brainstem gives rise to most of the twelve cranial nerves. A brainstem stroke affecting the brainstem and brain, therefore, can produce symptoms relating to deficits in these cranial nerves
altered smell, taste, hearing, or vision (total or partial)
drooping of eyelid (ptosis) and weakness of ocular muscles
decreased reflexes: gag, swallow, pupil reactivity to light
decreased sensation and muscle weakness of the face
balance problems and nystagmus
altered breathing and heart rate
weakness in sternocleidomastoid muscle with inability to turn head to one side
weakness in tongue (inability to stick out the tongue or move it from side to side)
If the cerebral cortex is involved, the CNS pathways can again be affected, but also can produce the following symptoms:
aphasia (difficulty with verbal expression, auditory comprehension, reading and writing; Broca’s or Wernicke’s area typically involved)
dysarthria (motor speech disorder resulting from neurological injury)
apraxia (altered voluntary movements)
visual field defect
memory deficits (involvement of temporal lobe)
hemineglect (involvement of parietal lobe)
disorganized thinking, confusion, hypersexual gestures (with involvement of frontal lobe)
lack of insight of his or her, usually stroke-related, disability
If the cerebellum is involved, ataxia might be present and this includes:
altered walking gait
altered movement coordination
vertigo and or disequilibrium
