AEB - Pathology of intracranial SOL

Infection, haemorrhage, infarction

List 3 key non-neoplastic intracranial space occupying lesions.

Acute bacterial meningitis, intracerebral abscess formation

What 2 conditions associated with infections cause raised intracranial pressure?

Intra-axial haemorrhage

vessel breakage causes bleeds directly into the brain tissue, most often caused by hypertension.

Hypertension

What is intra-axial haemorrhage most commonly caused by?

Head trauma

What is extra-axial haemorrhage most commonly caused by?

Extra-axial haemorrhage

vessel breakage causing bleeds into subdural, subarachnoid, or epidural space, most often caused by head trauma.

Vasogenic oedema

swelling occurring due to breakdown of blood-brain barrier breaksallowing fluid and proteins to enter the brain interstitium.

Cytotoxic oedema

swelling of brain cells due to intracellular fluid buildup with energy depletion.

Cerebral infarct

acute vascular occlusion causes necrosis in the brain, causing cytotoxic and vasogenic oedema and secondary haemorrhage.

Haemorrhagic infarct

blood flow returns to previously ischemic area and weakened vessels rupture causing bleeding into the infarct.

Primary CNS neoplasia

diverse group of tumours originating within the brain or spinal cord.

Gliomas, neuronal tumours, primary CNS lymphoma

List primary intra-axial neoplastic SOLs.

Meningiomas, bone tumours, Schwann cell tumours of cranial nerves

List primary extra-axial neoplastic SOLs.

Adult gliomas

intra-axial usually in cerebral hemispheres (supratentorial) with hypercellular and fibrillary background morphology. Grade 2 or higher.

Astrocytoma

glioma IDH-mutation confirmed with immunohistochemistical strain. Can be poorly defined in early grades as infiltrates tissue. Graded 2-4.

Olidodendroglioma

glioma with IDH-mutation confirmed with immunohistochemistical stain and 1p/19q co-deletion confirmed with molecular methods. Chicken wire/fried egg vasculature. Graded 2 or 3.

Glioblastoma

glioma with IDH-wild type (unmutated) with microvascular proliferation and pseudopalisading necrosis, with other defining molecular features. Well circumscribed with mass effects. Always grade 4.

Pilocytic astrocytoma

pediatric glioma within the cerebellum; characterised by Rosenthal fibres, areas of biphasic cellularity, and well circumscribed tumour. Always grade 1.

Meningioma

extra-axial tumour delineated with contrast on MRI, typically circumscribed and quite large. Grade 1-2 (rarely 3).

Secondary CNS neoplasia

tumours metastasised from elsewhere to the CNS.

Lung, breast, melanoma, kidney, GIT

List common origins for secondary CNS neoplasias.

Non-CNS lymphoma

unique origin to secondary extra-axial neoplasias.

Hydrocephalus

increase in cerebrospinal fluid volume in the brain.

Communicating

CSF build up occurs due to poor resorption from subarachnoid space or too much production, e.g. due to subarachnoid haemorrhage or meningitis.

Non-communicating

CSF build up occurs due to physical blockage stopping fluid from flowing correctly to leave the ventricular system, e.g. due to brain tumours or congenital malformations.

Gyral flattening and sulcal enfacement/narrowing, ventricular compression, midline shift

List key mass effects.

Meningitis, subarachnoid haemorrhage

List common causes of communicating hydrocephalus.

Brain tumours, congenital malformations

List common causes of non communicating hydrocephalus.

Subfalcine herniation

cerebral tissue is forced under the falx cerebri; usually least immediately severe but can compress the anterior cerebral artery supplying the cortex for contralateral leg motion (causes leg weakness).

Transtentorial herniation

cerebral tissue is forced under the tentorium cerebelli; consequent compression of posterior cerebral artery (to occipital cortex = cortical blindness), pons (possible haemorrhage, CN III (to eye).

Tonsillar herniation

cerebellar tissue is forced into the foramen magnum; most severe as compression of respiratory/cardiovascular centres in the medulla and can cause death.

Cushing reflex

high systemic pressure, bradykardia, and irregular respiration in response to raised intracranial pressure.

Pailloedema

swelling of optic disc due to intracranial pressure being transmitted along the optic nerve.

Headaches

irritation or compression of pain-sensitive meninges and intracranial blood vessels.

Seizures

SOL or ischemia disrupts normal electrical signalling increasing neuronal excitability.

Widespread ischemia, compression of nerves and brain regions, herniation

List 3 ways in which clinical effects occur from raised intracranial pressure.