Cerebrovascular_Disease_Trauma_Flashcards
Topic
Details
Introduction
Speaker: Prof. Steve Gentleman
Focus: Cerebrovascular disease and trauma, their mechanisms, impact, and management.
Context: Part of a broader lecture series covering neuropathology, including neuro-oncology, cerebrovascular issues, trauma, and neurodegenerative diseases.
Cerebrovascular Disease - Mechanisms of CNS Damage
Oedema (Edema):
- Definition: Excess accumulation of fluid in the brain parenchyma.
- Types:
- Vasogenic Oedema: Disruption of the blood-brain barrier (BBB) allowing fluid to escape from the vasculature into the brain.
- Cytotoxic Oedema: Cellular injury (e.g., hypoxia, ischaemia) causing cells to swell and rupture, releasing intracellular fluid.
- Consequences: Increased intracranial pressure (ICP) due to the fixed volume of the skull, leading to potential brain damage.
Mechanisms of Fluid Movement
Water transport across astrocytes.
Breakdown of tight junctions in endothelial cells (BBB disruption).
Fluid transport across ependymal cells (lining ventricles) into brain tissue.
Active expulsion of fluid from brain tissue into CSF or vasculature.
Hydrocephalus
Definition: Accumulation of cerebrospinal fluid (CSF) due to impaired circulation or absorption.
Types:
- Non-communicating (Obstructive) Hydrocephalus: Physical blockage in CSF flow, often at the cerebral aqueduct.
- Communicating Hydrocephalus: Impaired absorption of CSF into the venous sinuses, often due to meningitis.
Raised Intracranial Pressure (ICP)
Normal ICP: 7-15 mmHg in a supine adult.
Causes of Increased ICP:
- Space-occupying lesions (e.g., tumors).
- Generalized oedema.
Consequences: Risk of brain herniation due to fixed skull volume and rigid dural folds (e.g., tentorium cerebelli, falx cerebri).
Brain Herniation
Types:
- Subfalcine Herniation: Cingulate gyrus herniates under the falx cerebri due to unilateral hemispheric pressure.
- Transtentorial (Uncal) Herniation: Medial temporal lobe herniates through the tentorial notch into the posterior fossa.
- Tonsillar Herniation: Cerebellar tonsils herniate through the foramen magnum, compressing the brainstem.
Stroke
Definition: Clinical syndrome characterized by rapid development of focal or global neurological symptoms due to a vascular cause.
Types:
- Ischaemic Stroke: Blockage of blood flow leading to tissue infarction (most common type).
- Haemorrhagic Stroke: Bleeding within the brain due to vessel rupture.
- Transient Ischaemic Attack (TIA): Temporary blockage causing stroke-like symptoms, typically resolving within minutes to hours without permanent damage. A warning sign for potential future stroke.
Haemorrhagic Stroke
Intracerebral Haemorrhage:
- Cause: Hypertension is the most common cause, leading to rupture of small intracerebral vessels.
- Common Locations: Basal ganglia, cerebellum, brainstem.
- Symptoms: Severe headache, vomiting, loss of consciousness, focal neurological deficits.
Arteriovenous Malformations (AVMs):
- Definition: Congenital malformations of tangled blood vessels directly connecting arteries and veins.
- Symptoms: Haemorrhage, seizures, headache, focal neurological deficits.
- Treatment: Surgical removal, embolization, radiosurgery.
Cavernous Angiomas:
- Definition: Compact clusters of dilated blood vessels without intervening brain parenchyma.
- Symptoms: Seizures, headaches, focal neurological deficits, and potential for recurrent bleeding.
Subarachnoid Haemorrhage
Cause: Rupture of berry aneurysms, commonly in the circle of Willis.
Symptoms: Sudden, severe ‘thunderclap’ headache, vomiting, loss of consciousness.
Diagnosis: Lumbar puncture for CSF analysis, angiography.
Treatment: Surgical clipping or endovascular coiling of aneurysms.
Ischaemic Stroke
Definition: Tissue death due to ischaemia (lack of blood supply).
Causes:
- Atherosclerosis: Common in carotid arteries and at arterial bifurcations.
- Emboli: Clots traveling from the heart or large arteries to the brain.
Symptoms: Dependent on the affected vascular territory (e.g., middle cerebral artery, anterior cerebral artery, posterior cerebral artery).
Diagnosis: Imaging (CT, MRI) to differentiate between ischaemic and haemorrhagic stroke.
Treatment: Thrombolytics (e.g., tPA) for acute ischaemic stroke, contraindicated in haemorrhagic stroke.
Traumatic Brain Injury (TBI) - Types of TBI
Non-missile (Blunt) Trauma:
- Causes: Road traffic accidents, falls, assaults.
- Injuries: Acceleration-deceleration forces, rotational injuries.
- Consequences: Skull fractures, contusions, lacerations, diffuse axonal injury.
Missile (Penetrating) Trauma:
- Causes: Gunshot wounds, stabbing injuries.
- Consequences: Direct tissue damage, intracranial hemorrhage, infection risk.
Skull Fractures
Types:
- Linear: Simple break in the bone without displacement.
- Depressed: Bone fragments pushed inward, potentially compressing brain tissue.
- Basilar: Fracture at the base of the skull, often involving the middle ear or anterior cranial fossa, leading to CSF leakage (otorrhea, rhinorrhea).
Signs: Battle sign (bruising behind the ear), raccoon eyes (periorbital ecchymosis).
Contusions and Lacerations
Contusions: Bruising of the brain surface due to impact with the skull.
Common Sites: Frontal and temporal lobes, inferior surfaces of the hemispheres.
Coup-Contrecoup Injuries: Primary impact site (coup) and opposite site of brain impact (contrecoup).
Lacerations: Tearing of brain tissue, often involving the pia mater.
Diffuse Axonal Injury (DAI)
Definition: Shearing forces causing widespread damage to axons in the white matter.
Common Sites: Corpus callosum, brainstem, septum pellucidum.
Symptoms: Coma, severe neurological deficits.
Diagnosis: Difficult to detect on imaging, often inferred from clinical presentation and mechanism of injury.
