CNS CNS PathologyPathology

Melani H. Sionzon, MD, DPSPMelani H. Sionzon, MD, DPSP

Review: Principal cells of the Review: Principal cells of the CNSCNS

NeuronsNeurons

Glial CellsGlial Cells– AstrocytesAstrocytes– OlidodendrogliaOlidodendroglia– ependymaependyma

MicrogliaMicroglia

Meningothelial cellsMeningothelial cells

Features Unique to CNSFeatures Unique to CNS

Enclosed in a rigid bony compartmentEnclosed in a rigid bony compartmentAutoregulation of cerebral blood flowAutoregulation of cerebral blood flowDependent on glucose and high O2 supplyDependent on glucose and high O2 supplyCSF fills ventricles and spacesCSF fills ventricles and spacesLack a lymphatic circulationLack a lymphatic circulationCell have limited regenrative abilityCell have limited regenrative abilityImmunologically secludedImmunologically secludedBBB and blood CSF barrier separates the brain BBB and blood CSF barrier separates the brain from the rest of the body from the rest of the body

Intracranial compartmentsIntracranial compartments

Epidural spaceEpidural space

Subdural spaceSubdural space

Subarachnoid spaceSubarachnoid space

Cerebral parenchymal compartmentCerebral parenchymal compartment

Intravntricular spacesIntravntricular spaces

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

Pathologic ReactionsPathologic Reactions

Astrocytes - Gliosis – glial scarAstrocytes - Gliosis – glial scar

Microglia - glial nodulesMicroglia - glial nodules– Phagocytosis of dying neurons Phagocytosis of dying neurons

(neuronophagia)(neuronophagia)

Cerebral EdemaCerebral Edema

Vasogenic edema Vasogenic edema – blood brain barrier dysfunction, fluid accumulates blood brain barrier dysfunction, fluid accumulates

between neurons and glial cellsbetween neurons and glial cells

Cytotoxic edema Cytotoxic edema – fluid accumulates inside the cells (ischemia, hypoxia)fluid accumulates inside the cells (ischemia, hypoxia)

Interstitial edema Interstitial edema – results from increase CSF (dysfunction of brain CSF results from increase CSF (dysfunction of brain CSF

barrier)barrier)– Complication of hydrocephalusComplication of hydrocephalus

Gross Appearance of the brain in vasogenic Gross Appearance of the brain in vasogenic edemaedema

Common autopsy Common autopsy findingsfindings– Flattened broad gyriFlattened broad gyri– Narrowed slit-like sulciNarrowed slit-like sulci– Compressed lateral Compressed lateral

ventriclesventricles– Brain is heavier than Brain is heavier than

normal, soft; fluid seeps normal, soft; fluid seeps from cut surfacesfrom cut surfaces

– Signs of herniation may Signs of herniation may be seenbe seen

HerniationsHerniations

Cingulate herniation/ SubfalcineCingulate herniation/ Subfalcine– Cingulate gyrus compressed underneath the falx Cingulate 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 foramen Cerebellar tonsils are compressed in the foramen

magnummagnum– Life threateningLife threatening

Developmental DisordersDevelopmental Disorders

Cranial DysraphismCranial Dysraphism– AnencephalyAnencephaly– encephaloceleencephalocele

Spinal DysraphismSpinal Dysraphism– Spina bifida occultaSpina bifida occulta– MeningoceleMeningocele– MeningimyeloceleMeningimyelocele– Rachischisis Rachischisis

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

Spinal Cord InjuriesSpinal Cord Injuries

Hyperextension injuryHyperextension injury– Cervical spinalCervical spinal– Sudden posterior displacement of the head Sudden posterior displacement of the head – Rupture of anterior spinal ligamentRupture of anterior spinal ligament

Hyperflexion injuryHyperflexion injury– Impact force driving the head down and Impact force driving the head down and

forwardforward– Anterior contusion of the cervical spineAnterior contusion of the cervical spine

Intracranial BleedingIntracranial Bleeding

Epidural hematomaEpidural hematoma

Subdural hematomaSubdural hematoma

Subarachnoid hematomaSubarachnoid hematoma

Intracerebral hemorrhageIntracerebral hemorrhage

Intraventricular hemorrhage Intraventricular hemorrhage “hydrocephalus internus”“hydrocephalus internus”