This document discusses pathology of the central nervous system (CNS). It describes the principal cell types of the CNS including neurons, glial cells, meningothelial cells, and microglia. It outlines features unique to the CNS such as being enclosed in bone and relying on glucose and oxygen. Pathologic reactions of neurons and glial cells are described for conditions like acute injury, degeneration, and protein aggregation. Types of cerebral edema like vasogenic and cytotoxic edema are also summarized. Common CNS disorders, injuries, and bleedings are briefly outlined.

1. CNSCNS
PathologyPathology
Melani H. Sionzon, MD, DPSPMelani H. Sionzon, MD, DPSP

2. Review: Principal cells of theReview: Principal cells of the
CNSCNS
NeuronsNeurons
Glial CellsGlial Cells
– AstrocytesAstrocytes
– OlidodendrogliaOlidodendroglia
– ependymaependyma
MicrogliaMicroglia
Meningothelial cellsMeningothelial cells

13. Features Unique to CNSFeatures Unique to CNS
Enclosed in a rigid bony compartmentEnclosed in a rigid bony compartment
Autoregulation of cerebral blood flowAutoregulation of cerebral blood flow
Dependent on glucose and high O2 supplyDependent on glucose and high O2 supply
CSF fills ventricles and spacesCSF fills ventricles and spaces
Lack a lymphatic circulationLack a lymphatic circulation
Cell have limited regenrative abilityCell have limited regenrative ability
Immunologically secludedImmunologically secluded
BBB and blood CSF barrier separates the brainBBB and blood CSF barrier separates the brain
from the rest of the bodyfrom the rest of the body

14. Intracranial compartmentsIntracranial compartments
Epidural spaceEpidural space
Subdural spaceSubdural space
Subarachnoid spaceSubarachnoid space
Cerebral parenchymal compartmentCerebral parenchymal compartment
Intravntricular spacesIntravntricular spaces

15. Pathologic ReactionsPathologic Reactions
““Selective vulnerability”Selective vulnerability”
Pathologic reactions of neuronsPathologic reactions of neurons
– Acute injuryAcute injury
– DegenerationDegeneration
– Axonal reactionAxonal reaction
– Formation of neuronal inclusionsFormation of neuronal inclusions
– Vacuolization of cytoplasm and neurophilVacuolization of cytoplasm and neurophil
– Aggregation of abnormal proteinsAggregation of abnormal proteins
– NeuronophagiaNeuronophagia

16. Pathologic ReactionsPathologic Reactions
Astrocytes - Gliosis – glial scarAstrocytes - Gliosis – glial scar
Microglia - glial nodulesMicroglia - glial nodules
– Phagocytosis of dying neuronsPhagocytosis of dying neurons
(neuronophagia)(neuronophagia)

17. Cerebral EdemaCerebral Edema
Vasogenic edemaVasogenic edema
– blood brain barrier dysfunction, fluid accumulatesblood brain barrier dysfunction, fluid accumulates
between neurons and glial cellsbetween neurons and glial cells
Cytotoxic edemaCytotoxic edema
– fluid accumulates inside the cells (ischemia,fluid accumulates inside the cells (ischemia,
hypoxia)hypoxia)
Interstitial edemaInterstitial edema
– results from increase CSF (dysfunction of brain CSFresults from increase CSF (dysfunction of brain CSF
barrier)barrier)
– Complication of hydrocephalusComplication of hydrocephalus

18. Gross Appearance of the brain in vasogenicGross Appearance of the brain in vasogenic
edemaedema
Common autopsyCommon autopsy
findingsfindings
– Flattened broad gyriFlattened broad gyri
– Narrowed slit-like sulciNarrowed slit-like sulci
– Compressed lateralCompressed lateral
ventriclesventricles
– Brain is heavier thanBrain is heavier than
normal, soft; fluid seepsnormal, soft; fluid seeps
from cut surfacesfrom cut surfaces
– Signs of herniation maySigns of herniation may
be seenbe seen

19. HerniationsHerniations
Cingulate herniation/ SubfalcineCingulate herniation/ Subfalcine
– Cingulate gyrus compressed underneath the falxCingulate gyrus compressed underneath the falx
cerebricerebri
– Caused by unilateral hemispheric massCaused by unilateral hemispheric mass
Transtentorial herniation/ UncinateTranstentorial herniation/ Uncinate
– Uncus gyri herniate in the cerebellar tentoriumUncus gyri herniate in the cerebellar tentorium
Tonsillar herniationTonsillar herniation
– Cerebellar tonsils are compressed in the foramenCerebellar tonsils are compressed in the foramen
magnummagnum
– Life threateningLife threatening

22. Developmental DisordersDevelopmental Disorders
Cranial DysraphismCranial Dysraphism
– AnencephalyAnencephaly
– encephaloceleencephalocele
Spinal DysraphismSpinal Dysraphism
– Spina bifida occultaSpina bifida occulta
– MeningoceleMeningocele
– MeningimyeloceleMeningimyelocele
– RachischisisRachischisis

34. Physical InjuriesPhysical Injuries
Contusions (bruising)Contusions (bruising)
– ““Coup lesions” and “contre coup” contusionCoup lesions” and “contre coup” contusion
– Rapid accelaration/ decelerationRapid accelaration/ deceleration
Laceration (tearing)Laceration (tearing)
Diffuse Axonal InjuryDiffuse Axonal Injury
Traumatic vascular injuryTraumatic vascular injury
Penetrating woundsPenetrating wounds

35. Spinal Cord InjuriesSpinal Cord Injuries
Hyperextension injuryHyperextension injury
– Cervical spinalCervical spinal
– Sudden posterior displacement of the headSudden posterior displacement of the head
– Rupture of anterior spinal ligamentRupture of anterior spinal ligament
Hyperflexion injuryHyperflexion injury
– Impact force driving the head down andImpact force driving the head down and
forwardforward
– Anterior contusion of the cervical spineAnterior contusion of the cervical spine

36. Intracranial BleedingIntracranial Bleeding
Epidural hematomaEpidural hematoma
Subdural hematomaSubdural hematoma
Subarachnoid hematomaSubarachnoid hematoma
Intracerebral hemorrhageIntracerebral hemorrhage
Intraventricular hemorrhageIntraventricular hemorrhage
“hydrocephalus internus”“hydrocephalus internus”