Nervous System Pathology Flashcards
What is cerebral oedema?
what are the causes?
Cerebral oedema refers to brain parenchymal oedema which is caused by blood brain barrier disruption (vasogenic) or via direct injury (cytotoxic).
What is a hydrocephalus?
what are the causes?
there are two types- what are they?
Hydrocephalus is the excess of CSF within the ventricular system. CSF is produced in the choroid plexus and circulates through the ventricular system. If only a portion of the ventricular system is dilated the pattern is a non-communicating hydrocephalus. If
the whole system is dilated it is then a communicating hydrocephalus
What are the locations of haemorrhages?
Haemorrhages can occur in the
EPIDURAL (dural arterial bleed (e.g. middle meningeal artery) causing the dura to separate from the skull),
SUBDURAL (bridging veins from the cerebral hemispheres drain into the venous sinuses and bleeding occurs between the dura and the arachnoid layer)
and SUBARACHNOID (in the subarachnoid space).
What is hypertensive vascular disease characterised by??
Hypertensive cerebrovascular disease is characterised by lacunar infarcts, slit haemorrhages, hypertensive encephalopathy as well as intracerebral haemorrhage.
What is the main cuase of subarachnoid haemorrhage?
Subarachnoid haemorrhage is most frequently caused by the rupture of a saccular (berry) aneurysm. Vascular malformations can also be associated with risk of haemorrhage.
What kind of pathologies are associated with intracerebral hypertension?
hypertension, cerebral amyloid angiopathy and a rare cause, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).
What is a STROKE?
Sudden loss of brain function ± loss of consciousness
Clinical picture depends on the size and site of vessels
What is the aetiology of stroke?
90% occlusion (arterial thrombosis/embolus associated with atherosclerosis)
• 10% rupture leading to intracerebral haemorrhage
Notes:
STROKE- rupture causes two types of intracerebral haemorrhage primary secondary or INFECTIVE ANEURYSM RUPTURE
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Primary intracerebral haemorrhage
• Hypertension is the most common cause
• Cerebral amyloid angiopathy
• CADISIL
Secondary intracranial haemorrhage
• coagulation disorders, vessel wall damage, vascular malformation
or eg. berry anuerysm rupture
Describe what happens in epidural haematoma
Epidural: Dura normally fused with periosteum. Dural arteries including the middle meningeal artery (esp with temporal skull fractures) are injured. This is arterial blood.
Describe what happens in subdural haematoma
Subdural haematoma: Subdural is between the inner surface of the dura mater and the outer arachnoid layer is the subdural space. Due to the bridging veins being torn – usually empty into the saggital sinus and other dural sinuses are prone to tearing.
What is the aetiology of subarachnoid haemorrhage
Aeitology:
extension of intracerebral haemorrhage,
direct bleeding into the subarachnoid space, ie rupture berry aneurysm.
What are some RFs for berry aneurysm rupture
develop over time >40yo. Associated with AVM, coarctiation of aorta, adult polycystic kidney disease, CT disorders, fibromuscular dysplasia <40yo.
Found at the branch points around the circle of Willis, may be multiple. Note that they may rupture leading to intracerebral (burrowing) or subdural (rare) bleeding.
Describe the macroscopic appearance of infarction
Infarction
Pale initially
Hours to days grey matter becomes congested engorged with dilated blood vessels and minute petechial haemorrhage
May become haemorrhagic
Describe the macroscopic appearance of haemorrhage
- intracerebral
- subarachnoid
Intracerebral
• Haematoma within brain parenchyma
• Direct damage by compressing surrounding tissue
Subarachnoid
• Bleeding into CSF within the subarachnoid space.
What is papilloedema a sign of?
Increased intracranial pressure
What are the clinical manifestations of a subarachnoid haemorrhage?
Symptoms of SAH include a severe headache with a rapid onset (“thunderclap headache”), vomiting, confusion or a lowered level of consciousness, and sometimes seizures.In general, the diagnosis is confirmed with a CT scan of the head, or occasionally by lumbar puncture. Treatment is by prompt neurosurgery or radiologically guided interventions with medications and other treatments to help prevent recurrence of the bleeding and complications.
What are the microscopic features of subarachnoid haemorrhage?
Can see infarcted area, and area of healthy tissue.
Infarct- granulation response, formation of new capillaries as part of the healing process. Infiltrating phagocytic
cells.
GHOST NEURONS can only see contour of them, nucleus already gone.
Further in where granulation taking place- find large reactive astrocytes (large cytoplasm, acidophilic contents).
inbetween- dense fibrillary reaction (similar role to fibroblasts but don’t lay down collagen) form a dense network
as a way to preserve the architecture of the damaged tissue.
Large cell- gameistocytes?, microcytes (large,
look blue- have a weird nucleus and seem basophilic because of what they phagocytose- mainly haemociderin
and lipid).
What are the clinical features of intracerebral haemorrhage
headache, nausea, and vomiting lethargy or confusion sudden weakness or numbness of the face, arm or leg, usually on one side loss of consciousness temporary loss of vision seizures
What are the signs/symptoms of bacterial meningitis?
What are the common causes in adults?
Symptoms: may be absent in extremes of age.
Onset often abrupt, FEVER, neck stiffness, headache, vomiting, photophobia, seizures, altered mental state or focal neurological defect. Look ill, irritability, apathy, drowsiness, unsconsciousness
Signs: neck and spine stiffness, Kernigs sign (+)
Community acquired, most commonly in adults:
• Streptococcus pneumoniae
• Neiserria meningitides
• Listeria monocytogenes
Viral meningitis: symptoms, causes
Viral Meningitis
Non specific constitutional symptoms; diarrhoea, fever: vomiting, anorexia, rash, cough, myalgia
Meningitis
Microscopic features
Examination under the microscope reveals the presence of numerous viable and degenerate polymorphs filling the subarachnoid space (1).
A few scattered mononuclear macrophages (2) are present but these are insignificant compared to the numbers of neutrophils present. This acute inflammatory exudate extends into the brain sulci (1) and to a limited extent along the Virchow-Robin spaces which are in fact continuations of the subarachnoid space around penetrating blood vessels (3).
Meningitis:
Macroscopic features
The mounted specimen shows an extensive purulent exudate in the subarachnoid space but chiefly around the brain stem, in the interpeduncular fossa, extending into the Sylvian fissures and spreading over the frontal, and to a lesser extent, the parietal lobes. The cut surface of the brain shows a purulent ependymitis involving the ventricles.
CNS TUMOURS
What ar the most common primary brain tumours tumours?
what does this include?
Primary tumours of the CNS account for 20% of cancers in childhood. 70% of childhood CNS tumours arise in the posterior fossa. Some tumours while appearing benign histologically infiltrate widely making resection, without major deficit, difficult. Prognosis can also be poor if tumours are located in a critical region or are inoperable. Tumours are segregated into one of four grades based on their biological behaviour (I-IV).
Gliomas are the most common group of primary brain tumours and include astrocytomas, oligodendrogliomas and ependymomas.
The most malignant gliomas only rarely metastasize outside the CNS.
Astrocytomas
what are the two main types?
What is more common?
• Astrocytes: star shaped cells that have multiple functions including structural, blood brain barrier maintenance and regulation of the extracellular environment. Tumours include: astrocytomas and glioblastomas
Can be considered in two major categories: infiltrating and non- infiltrating. INFILTRATING astrocytomas account for 80% of adult brain tumours most often occurring in the 40-60s. Usually found in cerebral hemispheres. Presenting features include seizures, headaches and focal neurological deficits (depending on site).
Tumours range from diffuse (II), anaplastic (III), glioblastoma (IV). Grade I is limited to pilocytic astrocytoma.
The mean survival- low grade: 5 year, high grade- 15 months.
Oligodendromas
what % of gliomas?
what grade?
make 5-15% of gliomas and are most common in the 40-50s. These are grade II but can be anaplastic.
Oligodendrocytes: these cells produce the myelin sheath.
Common 40s-50s, may have a long clinical history of neurological disturbance. Most often found in the cerebral hemispheres. Well circumscribed, gelatinous, gray masses often with cysts, focal haemorrhage and calcification.
