Congenital CNS Pathology Flashcards
Factors involved in the development of CNS congenital disorders include:?
- Maternal and fetal infections
- Drugs
- Anoxia
- Ischemia
- Genetic
The most common developmental CNS abnormality is ?
Neural Tube defects
- results from defective closure of the neural tube
- occurs at the two ends of the nueroaxis
What deficiency is implicated in Neural tube defects ?
Folate deficiency
Anencephaly is the ?
Absence of cranial vault, incompatible with life
NTD affecting the spinal cord include ?
- Myelocele
- meningomyelocele
- Meningocele
- Spinal bifida occulta
Spinal bifida occulta is ?
A bony defect of the vertebral arch
Meningocele is ?
- Bony defect with the outpouching of the meninges.
- Protrusion of the meninges (filled with csf) through a defect in the skull or spine
Meningomyelocele is?
Defective formation of the bony arch with cystic outpouching of the meninges, spinal cord and spinal roots
Myelocele is?
Defective bony arch with complete exposure of the spinal cord
The most consistent defect in neural tube defects is ?
Defective formation of the bony arch
Complications of NTD?
Paraplegia and urinary incontinence from birth
Mention 2 posterior fossa anomalies ?
- Arnold-Chiari malformations (1& 2)
- Dandy-Walker malformation
Typical features of Type 1 Arnold chiari malformations ?
- Mostly asymptomatic
- Downward displacement of the cerebellar tonsils
- could involve syringomyelia
Typical features of type 2 Arnold chiari malformations
- Most often symptomatic
- Faulty cranio-spinal junction resulting in small posterior fossa
- there’s Downward displacement of the cerebellar vermis and tonsils
Complications of type 2 A.chiari malformation?
- Compression of the 4th ventricle
- compresses aqueduct and medulla
- Obstructive hydrocephalus
- Frequent lumbar meningomyelocele
The acronym TAS for type 1 Arnold chiari malformation represents what?
T - Tonsil herniation (cerebellar tonsils)
A - Asymptomatic
S - Syringomyelia
The acronym MAD for type 2 Arnold chiari malformation represents what?
M - Meningomyelocele (Lumbar)
A - Aqueductal and medulla compression
D - Dangerous symptoms (Hydrocephalus, paralysis)
The development of a fluid filled cavity within the spinal cord is called?
Syringomyelia
What can you remember about Syringomyelia ?
- Ependymal-lined, CSF filled channel that forms parallel to and connected with the central canal
- 90% of cases associated with Arnold-chiari type 1
- 10% post traumatic or intraspinal tumors
- Syrinx enlarged progressively and destroys the spinal parenchyma
- symptoms: paralysis and loss of sensory functions
Hydromyelia is?
- an abnormal widening of the central canal of the spinal cord.
- Dilation of the central canal
What part of the spine is most commonly affected by syringomyelia?
The cervical region
Mention 5 neural tube defects?
Meningomyelocele
Anencephaly
Spinal bifida occulta
Encephalocele
Myelocele
Meningocele
Forebrain anomalies include ?
- Microcephaly- Small head size
- Lissencephaly - Absence of convolutions (folds) in the cerebral cortex
- Agyria - Absence of gyri on the surface of the cerebral cortex (complete lissencephaly)
- Megalencephaly - a condition in which an infant or child has a large, heavy, and potentially malfunctioning brain.
Forebrain anomalies also include?
- Polymicrogyria - multiple small gyri (microgyri) creating excessive folding of the brain… CMV is a cause
- Neuronal heterotopias; brain malformations resulting from deficits of neuronal migration
- Holoprosencephaly; failure of the prosencephalon (the embryonic forebrain) to sufficiently divide into double lobes of cerebral hemispheres
- Agenesis of the corpus callosum
CNS traumas can result in three categories of injury namely?
- Skull fractures
- Parenchyma injury
- Vascular injury
Injury to the head may be ? And may cause ?
- Penetrating or blunt
- Open or closed injury
The magnitude, distribution and consequence of traumatic brain lesions depends on ?
- The shape of the object causing the injury
- The force of impact
- Whether the head is in motion at the time of injury
- Anatomical location of the lesion
- Limited capacity of the brain for functional repair
Injury of brain parenchyma may be silent in ? Severely disabling in? Or fatal in?
Silent - Frontal lobe injury
Severely disabling - spinal cord injury
Fatal - Brainstem injury
Trauma to the CNS (Cranium cranial cavity and brain) can cause ?
- Skull fracture
- Brain concussions
- Contusions
- Diffuse axonal injury
Trauma to the CNS (Blood vessel rupture) can cause
- Epidural hemorrhage
- Subdural hemorrhage
- Subarachnoid hemorrhage
- Intraparenchymal hemorrhage
Types of cerebral herniations that can result from CNS Trauma;
Subfalcian herniation (cingulate gyrus)
Transtentorial herniation (uncal)
Cerebellar tonsillar herniation
Most common cause of cerebral palsy is?
Perinatal brain injury
What is the germinal matrix?
A highly cellular and highly vascularized region in the brain out from which cells migrate during brain development.
What causes germinal matrix hemorrhage?
The blood vessels of the germinal matrix are weak walled and fragile and predisposed to hemorrhage.
Common is infants born before 32 weeks gestation
Periventricular leukomalacia?
PL is an injury to the white matter in the brain. White matter softens and dies around the lateral ventricles, leaving fluid-filled cysts.
PL is a white matter lesion in premature infants that results from hypotension, ischemia, and coagulation necrosis at the watershed zones of deep penetrating arteries of the middle cerebral artery.
Multi-cystic encephalopathy ?
- Occurs following prenatal or perinatal hypoxia-ischemia
- multiple brain infarcts occurring early in pregnancy
- varying sized cystic lesions in the brain encountered in developing fetuses or infants.
Cerebral palsy is defined as?
Non-progressive motor deficit related to prenatal and perinatal neurological insults
The major risk factor for cerebral palsy is ?
Prematurity
Clinical manifestations of cerebral palsy ?
- Dystonia - Involuntary muscle contractions
- Spasticity - abnormal muscle tightness due to prolonged muscle contraction
- Ataxia - Impaired balance or coordination
- Athetosis - slow, involuntary, and writhing movements of the limbs, face, and other muscle groups
- Paresis - Reduction in muscle strength with a limited range of voluntary movement.
Ischemic infarcts occurring within the periventricular white mater is called?
Periventricular leukomalacia
Ischemic infarcts occurring within the cerebral hemisphere
Multi-cystic encephalopathy
Intraparenchymal hemorrhage occurring within the germinal matrix often occurs between?
The thalamus and caudate nucleus and can extend into the ventricular system
Ulegyria ?
Thin, gliotic gyri due to perinatal cortical ischemia
Status marmoratus reflects ?
Ischemic neuronal loss and gliosis in the basal ganglia and thalamus associated with irregular myelin formation
When bone shifts into the cranial vault by more than its thickness is called?
Displaced fracture
Accidental falls tend to involve which part of the skull?
The occiput
There’s secondary basal skull involvement, lower CN or cervicomedullary symptoms and csf discharge and/or meningitis
Trauma occurring as a consequence of syncope tends to involve the?
The frontal skull
Diastatic fracture - occur when there is a separation of the cranial sutures, most commonly with the lambdoid suture
Concussion is caused by?
Change in the momentum of the head (head impact against a rigid surface)
Clinical presentation of concussion?
- Loss of consciousness and reflexes
- temp respiratory arrest
- amnesia of the event
- post concussive neuropsychiatric syndromes
Chronic traumatic encephalopathy (CLE)?
Associated with repeated head injuries and blows to the head.
Cognitive impairment with distinct pathological findings
Contussions are caused by?
Impact of parts of brain against inner Calvarial surfaces
There’s bruising to the brain that results from vessel and tissue disruption
Site of injury of contusion?
Crests of orbital gyri in frontal and temporal lobes
- Coup - site of injury
- Contrecoup - site diametrically opposite to injury
- They develop when the head is mobile at the time of impact
Signs of Acute contusions;
Hemorrhage of the brain tissue in a wedge shaped area
areas of hemorrhage and tissue disruption
Signs of subacute contusion?
Necrosis and liquefaction of brain
What are Remote contusions?
Depressed area of the cortex with yellow discoloration (Plaque Jaune)
Diffuse axonal injury is caused by ?
- Injury to the white matter due to acceleration and deceleration
- Damage to the axons at nodes of ranvier
- impairment of axoplasmic flow
Diffuse axonal injury has a predilection for which areas of the brain?
- Corpus callosum
- Periventricular white matter
- Hippocampus
- cerebral and cerebellar peduncles
Clinical manifestation of diffuse axonal injury?
Coma after trauma without evidence of direct parenchymal injuries
Histopathology of Diffuse axonal injury ?
- Axonal swellings appreciable in the white matter
- Focal hemorrhage
- Subsequently replaced by degenerated fibers and gliosis (fibrosis in the Brain)
Lesion to the thoracic segment of the spinal cord or below results in?
Paraplegia (paralysis in left and right legs)
Lesions to the cervical segments of the spinal cord results in ?
Tetraplegia (paralysis in all 4 limbs)
(C1-C8)
Lesions above C4 results in?
Respiratory arrest due to paralysis of the diaphragm
Acute and chronic finding of spinal cord injury ?
Acute - Hemorrhage, necrosis, white matter axonal swellings
Chronic - necrotic lesions become cystic and gliotic
Epidural hematomas result from?
The rupture of Dural arteries, most commonly middle meninges artery
- Usually associated with skull fracture
Complication of epidural hematoma?
Leads to cerebral herniation (sulfacrine mostly) if not promptly evacuated
Classical clinical presentation of epidural hematomas ?
Lucid intervals - Talk and die syndrome
Whats the underlying mechanism behind subdural hemorrhage?
It results from tearing of the bridging veins
bridging veins drain the venous blood from the cortical surface, through the subarachnoid and subdural spaces and into the superior sagittal sinus
The most susceptible category of people to subdural hemorrhage are ?
Geriatric patients with cerebral atrophy even after minor trauma
Clinical manifestations of subdural hemorrhage?
- Headache - Slowly progressive and non-localizing
- Drowsiness and confusion - within 48 hours of injury
- Focal neurological deficit
- Dementia
Why does chronic subdural hematoma occur?
Subdural hematoma can cause recurrent bleeding due to hemorrhage from thin-walled vessels of granulation tissue
Granulation tissue forms during the healing process of a wound, containing fibroblasts and new blood vessels which are thin walled
There’s accumulation of what type of blood in epidural hematoma and subdural hematoma ?
- Epidural hematoma - Arterial blood accumulates between the dura and the skull
- Subdural hematoma - Venous blood accumulates between the dura and the arachnoid matter
Sequelae of brain trauma ?
- epilepsy
- meningioma
- infectious disease
- psychiatric disorders
- Post traumatic hydrocephalus
- Post traumatic dementia (Dementia pulgilistica)
How does post traumatic hydrocephalus occurs?
Occurs when hemorrhage into the Subarachnoid space obstruct csf resorption
Post traumatic dementia is also called ?
Dementia pulgilistica
Post traumatic dementia clinical findings?
Consequence of repeated head trauma
- hydrocephalus
- corpus callosum thinning
- diffuse axonal injury
- amyloid plaques
- neurofibrillary tangles
Define brain herniation?
Brain herniation is the displacement of brain issue past rigid dural folds (the falx and tentorium) or through an opening in the skull due to increased ICP
Causes of increased ICP?
- Space occupying lesion
- Cerebral edema
- Increased venous pressure obstruction of the CSF
Space occupying lesions include ?
Brain tumor
Edema
Abscess
Contusions
Hematoma
Symptoms of raised ICP?
Cushings reflex
Initial headache, vomiting and, nauseas
Blurry vision
Drowsiness
Altered mental status
Lethargy
Cushings reflex include?
- Hypertension (widened pulse pressure)
- Bradycardia
- cheyne stokes breathing (irregular respiration)
The most common form of herniation is?
Sub-falcine (Cingulate) herniation
What happens in subfalcine herniation ?
The cingulate gyrus is displaced underneath the falx cerebri, to the opposite side
Clinical significance of cingulate herniation?
Compression of the anterior cerebral artery
Compression of ACA may result in?
- Ischemia in the frontal and parietal lobes
- Contralateral leg weakness
- Impaired/loss of consciousness
What happens in Cerebellar tonsillar herniation ?
- Displacement of the cerebellar tonsils through the foramen magnum
- compression of the brain stem, RAS, cardiorespiratory arrest
Decorticate posturing involves?
- while your arms flex upward and hold tensely to your chest.
- legs being held straight out and the toes being pointed downward
- the head and neck being arched backward
Brainstain compression features
- Midbrain compression; Midsized unreactive pupils
- Pontine hemorrhage: Pinpoint unreactive pupils
- Abnormal posturing
- coma
What happens in Transtentorial (uncal) herniation?
Uncal of temporal lobe displaces over the free edge of the tentorium cerebelli
Clinical significance of Uncal herniation?
- Compression of the occulomotor nerve
- compression of the Posterior cerebral artery
- compression and rupture of the paramedian basilar artery branches (Duret hemorrhages)
Clinical presentation of uncal herniation?
1) Ipsilateral oculomotor nerve (CN3) palsy
- Ipsilateral Fixed and dilated pupils
2) Paralysis of Oculomotor muscles later leads to
- ** Ipsilateral Ptosis**
- ipsilateral inferiorlateral gaze (down and out gaze)
3) compression of Ipsilateral PCA
- contralateral Homonymous hemianopsia with macular sparing
- contralateral hemiparesis/hemiplegia
4) compression of the contralateral cerebral peduncle against the tentorium
- Kernohan notch (Ipsilateral hemiparesis/hemiplegia)
Duret hemorrhage occurs from the rupture is what artery?
- Paramedian basilar artery branches
- Very fatal
What is cerebral edema??
Accumulation of intercellular fluid in the brain parenchyma
Types of Cerebral edema?
1) Vasogenic Cerebral edema
2) Cytotoxic cerebral edema
3) Interstitial cerebral edema
Vasogenic Cerebral edema is associated with what??
- Increased vascular permeability leads to the focal or generalized accumulation of intercellular fluid
Cytotoxic Cerebral edema
- Increased intracellular fluid secondary to endothelial neuronal or glial injury (after anoxia or toxic metabolic disturbances)
Interstitial cerebral edema?
Fluid from the ventricular system transudates across the ependymal lining secondary to increased ICP
