What must be true for pressure to be stable?
For pressure to be stable must be (within certain limits) correct amount of brain tissue/blood/CSF
What keeps the brain in place?
There are thick tough fibrous sheets inside that keep the brain in place
- Falx cerebri
- Tentorium cerebelli
What is the opening to the spinal cord called?
Foramen magnum
How can the brain move around the falx?
Brain cannot go through falx, but can go round edge
The brain cannot go through the skull, but can move down through…
Foramen magnum
What localise lesions can raise intracranial pressure?
- Haemorrhage
- Tumour
- Abscess
What generalised pathology can raise intracranial pressure?
Oedema post trauma
What is a localised haemorrhage called?
Haematoma
What are localised lesions also known as?
Space occupying lesions (SOL)
What are the effects of SOL?
- Amount of tissue increases
- Raises intra cranial pressure
- Cause internal shift (herniation) between the intracranial spaces
What internal shift can SOL cause?
- Right-left or left-right
- Cerebrum moves inferiorly over edge of tentorium (uncal herniation)
- Cerebellum moves inferiorly into foramen magnum (coning)
What are the different types of brain herniation?
- Cingulate
- Central
- Uncal
- Cerebrotonsillar
- Upward
- Transcalvarial
What types of shift is subfalcine herniation?
Midline shift
What happens in tentorial (uncal) herniation?
- Brain herniates inferiorly at side of tentorium
- Aqueduct is crushed and narrow
What type of herniation results in brainstem death?
Cerebellar tonsillar herniation
What occurs in cerebellar tonsil herniation?
Tonsils move inwards and downwards and crush brainstem
What does swelling and shift cause?
Localised ischaemia
What are the signs and symptoms of increased intracranial pressure?
- Squeeze on cortex and brainstem: morning headaches and sickness
- Squeeze on optic nerve: papilloedema
What stages occur as pressure increases?
- Pupillary dilation
- Falling GCS
- Brain stem death
Why do pupils dilate with increased pressure?
Squeeze and stretch on cranial nerve 3
Why does the GCS fall with increasing pressure?
Squeeze on cortex and brainstem
Why does brain stem death occur with increasing pressure?
Squeezing downwards of cerebellum into foramen magnum with crushing of brainstem
What are the 2 types of classification of tumours within the CNS?
- Primary tumours
- Secondary (metastatic tumours
Other than CNS tumours what other intracranial tumours can occur?
Cells originating outside brian and spinal cord(eg meningioma)
Give examples of primary intracranial tumours.
- Gliomas (glioblastoma, astrocytoma, oligodendroglioma, ependymoma)
- Medullablastoma
- Meningioma
- Schwannoma, neurofibroma
- Adenoma
- Lymphoma
- Haemangioblastoma
What metastatic malignancies can occur in the brain?
- Breast
- Lung
- Kidney
- Colon
- Melanoma
Who is brain metastatic disease rare in?
Children
Give examples of glial cell tumours.
Gliomas (glioblastoma, astrocytoma, oligodendroglioma, ependymoma)
Give an example of embryonic neural cell tumours.
Medullablastoma
Give examples of nerve sheath tumours.
- Scwhannoma
- Neurofibroma
Give an examples of an Arachnoidal cell tumour
Meningioma
Give an example of a pituitary gland tumour
Adenoma
Give an example of a lymphoid cell tumour.
Lymphoma
Give an example of a capillary vessel tumour.
Haemangioblastoma
What intracranial tumours are derived from brain cells?
- Gliomas
- Medullablastomas
What intracranial tumours are derived from cells surrounding or originating outside the brain?
- Meningiomas
- Scwhannoma
- Neurofibroma
- Adenoma
- Lymphoma
- Haemangioblastoma
What intracranial tumours are malignant?
- Gliomas
- Medullablastomas
Where do most CNS tumours occur in adults?
Majority above tentorium
Where do most CNS tumours occur in children?
Majority below tentorium
What do gliomas resemble?
Resemble cells of glial differentiation
What is the macroscopic appearance of gliomas?
Diffuse edges – not encapsulated
Gliomas are malignant but what do the not do?
Malignant but do not metastasise outside the CNS
What are tumours derived from astrocytes called?
Astrocytoma
What are tumours derived from oligodendrocytes called?
Oligodendroglioma
What are tumours derived from ependymal cells called?
Ependymoma
What do astrocytes look like?
- Star shaped cells
- Long processes support other cells structurally and biochemically
Give 2 examples of types of astrocytoma.
- Low grade astrocytoma
- Glioblastoma
What do low grade astrocytoma’s look like on microscopy?
Bland cells on microscopy (similar to normal astrocytes)
How fast do low grade astrocytomas grow?
Very slowly
What is the most malignant astrocytoma?
Glioblastoma
What is another name for glioblastoma?
Glioblastoma multiforme
How doe glioblastomas appear on microscopy?
Cellular, atypical tumour, with necrosis under microscope
How fast do glioblastomas grow?
Grow quickly – often present as large tumours
What is a medullablastoma?
Tumour of primitive neuroectoderm (primitive neural cells)
Who are usually affected by medullablastomas?
Children
Where are medullablastomas usually located?
Posterior fossa, especially brainstem
How do medulloblastoma look?
Sheets of small undifferentiated cells
What are meningiomas derived from?
From “arachnocytes” – cells that make up the coverings of the brain
What type of tumours are meningioma’s?
Benign: they do not metastasie
How can meningioma’s cause damage?
They are locally aggressive and can invade the skull
How fast do meningiomas grow?
Slow growing
How are meningiomas often treated?
Often resectable
How do meningiomas appear on microscopy?
Bland cells forming small groups which whorl around each other resembling an arachnoid granulation, sometimes with calcification
What is the calcification sometimes present in meningiomas called?
The calcification is sometimes called psammoma (from ‘grain of sand’) body formation
Where do nerve sheath tumours occur?
Around peripheral nerves – intracranial and extracranial
What do normal Schwann cells do?
Normal schwanncells wrap around peripheral nerves and form electrical insulation
What is an acoustic neuroma?
8th vestibulocochlear nerve schwannoma, at angle between pons and cerebellum
How do acoustic neuromas present?
Unilateral deafness
What type of tumours are acoustic neuromas?
Benign lesions but technically difficult to remove
What type of tumour is a pituitary adenoma?
Benign
Where are pituitary adenomas located?
Pituitary fossa
What do pituitary adenomas often secrete?
Often secrete a pituitary hormone
How do pituitary adenomas grow?
Grow superiorly and impinge on optic chiasma resulting in visual signs
Why are CNS lymphomas difficulty biopsy?
Often deep and central site in brain
Why are CNS lymphomas difficult to treat?
Difficult to treat as drug do not cross blood-brain barrier
What do CNS lymphomas generally not do?
Generally do not spread outside of CNS
What are CNS lymphomas?
- High grade neoplasm
- Usually diffuse large B-cell lymphoma
What is a Haemangioblastoma?
Space occupying tumour of blood vessels
Where are Haemangioblastoma usually found?
Cerebellum
What complication may Haemangioblastoma result in?
They may bleed
What are most secondary tumours?
Carcinomas
What is the histological appearance of a secondary tumour?
Histology is that of the primary tumour