Path - Brain Written

Front 1

Arnold-Chiari malformation (chiari II)

Back 1

Defect in skull formation resulting in deficient posterior fossa volume.
Braistem and cerebellum affected.
Vermis and caudal medulla pusched into spinal canal.
Midbrain roof deformed.
Hydrocephalus usually a feature.
Usually accompanied by lumbosacral myelomeningocele.

Front 2

Dandy-Walker malformation

Back 2

Arrested/failed hindbrain development.
Affects cerebellar vermis and 4th ventricle.
Vermis partially or entirely replaced by cystically dilated 4th ventricle.

Front 3

Pediatric Rule of 70

Back 3

70% derived from primitive CNS precursor cells of glia. (medulloblastoma, astrocytoma, ependymoma)

70% located below tentorium cerebelli.

Front 4

Adult Rule of 70

Back 4

70% located above tentorium

Front 5

Most common CNS tumors in adults

Back 5

High grade astrocytomas
Metastatic carcinoma
Meningioma
Pituitary adenoma
Schwannoma

Front 6

Subfalcine (cingulate) herniation

Back 6

Cingulate gyrus pushed under falx cerebri by expanding frontal/parietal mass.
May compress branches of anterior cerebral actery (ACA) with infarction in ACA distribution.

Front 7

Transtentorial (uncal, hippocampal) herniation

Back 7

Medial most part of temporal lobe (uncus) pushed out over edge of tentorium and wedged into cleft between tentorium and cerebral peduncle of midbrain.
Compresses CN III -> fixed dilated pupil.
May push midbrain against contralateral tentorium -> ipsilateral hemiparesis from peduncular compression.
Compresses posterior cerebral artery (PCA) with infarction in PCA distribution.

Front 8

Tonsillary (cerebellar) herniation

Back 8

Inferior most parts of cerebellar hemispheres (tonsils) pushed into foramen magnum, compressing respiratory centers of medulla.
Tonsillar herniation may result from spinal tap in patient with increased intracranial pressure.
Check for papilledema, obtain CT and/or MRI before tapping patient with suspected increased ICP.
**risk of respiratory failure