Systems Path I Exam 3 - CNS

Ischemia results in dysfunction within __

5-10 seconds

Neuron cell death starts within __ of severe ischemia

5 minutes

States that groups of neurons have different metabolic requirements, NTs used and distribution of connections

Selective vulnerability

Major glial cell responsible for repair or scar formation

Astrocytes

Glial cell hypertrophy, hyperplasia, and scar formation following injury

Gliosis

Glial cell type that are myelin producers of the CNS

Oligodendrocytes

A resident phagocyte of the CNS (glial cell)

Microglial cells

Glial cell type that produces CSF (lines ventricular system and central canal)

Ependymal cells

A displacement of brain tissue around rigid structures due to increased ICP or mass effect (compression of structures causes HA, nausea, loss of consciousness)

Brain herniation

Displacement of cingulate gyrus under falx cerebri due to asymmetric pressure on one cerebral hemisphere

• Causes compression of anterior cerebral artery (*contralateral leg weakness, aphasia if dominant hemisphere)

Subfalcine/cingulate brain herniation

Displacement of uncinate fasciculus around tentorium cerebelli

• Compression of CN 3 (causes mydriasis - “blown pupil”; anisocoria - unequal pupil size; impaired eye movement down and out)

• Compression of descending motor fibers (hemiparesis - causes compression on opposite side from herniation - “Kernohan phenomenon”)

• Compression of posterior cerebral artery (ischemia to primary visual cortex and vision loss)

• Duret hemorrhage (disruption of vessels in pons)

Transtentorial/uncinate brain herniation

Displacement of cerebellar tonsils through foramen magnum

• compression of brainstem/MO (compromises respiratory and cardiac regulatory centers - rapidly fatal)

Tonsillar brain hernation

An extracellular edema where fluid accumulates outside of cells (disrupts BBB - infxn, inflammation)

Vasogenic edema

Intracellular edema causing cellular swelling (*hypoxia/ischemia in injured neurons; toxic ammonia from liver failure)

Cytotoxic edema

Dilation of pupil occurs in this condition

Mydriasis

Unequal pupil size occurs in this condition

Anisocoria

Large arterial vessel bleed at the branch points of Circle of Willis (MC in anterior circulation of circle); causes a “thunderclap headache”, observed loss of consciousness, and onset of HA during exertion

Saccular/“berry” aneurysm rupture

Temporary neurological dysfunction (<24 hrs) where there is no infarct, but symptoms are similar to stroke

Transient ischemic attack (TIA or “mini stroke”)

Paralysis of CN 7, causing weakness to half of face (including the forehead - inability to raise eyebrow or completely close eye)

Bell’s Palsy

How does a stroke differ from Bell’s palsy?

Bell’s Palsy - weakness in ENTIRE half of face

Stroke - weakness in half of face, but able to retain forehead movements

Cerebral contusion on the side of impact

Coup injury

Cerebral contusion on opposite side of impact due to recoil

Contrecoup injury

Cutting of brain parenchyma (trauma)

Cerebral laceration

Where does 34% of ischemic strokes occur? (Which vessel?)

Middle cerebral artery

Lesion of an ___ generally causes spastic weakness (motor impairment)

UMN

Neuronal injury pattern of swelling of soma and axons occurs in __

Reversible injury

Neuronal injury patter of soma shrinking and “red neurons” occurs in __

Irreversible injury (neuron cell death)

Factors that take up space in the cranium and increase ICP

Blood, edema (neuron swelling, brain trauma, infection), CSF, tumors

General increased volume of CSF within ventricular system, MC due to decreased resorption of CSF or impaired flow (overproduction of CSF/tumor of choroid plexus is rare)

Hydrocephalus

Born with malformation in ventricular system causing increased amount of CSF

Congenital hydrocephalus

An increase in CSF due to blockage (tumor, edema, blood) or overproduction (tumor)

Acquired hydrocephalus

Atrophy of brain (secondary loss of brain volume from stroke or neurodegenerative disorder) causing increased in CSF

Hydrocephalus ex vacuo

What is the 5th MC cause of mortality in the US and the #1 cause of neurological morbidity?

Cerebrovascular disease

MC type of stroke; MC due to embolic occlusion - blockage material originating from heart (paradoxical embolism - DVT that has moved into left side of heart)

Ischemic stroke

Ischemic stroke is most commonly caused by __

Embolic occlusion originating from the heart

Small vessel ischemic stroke that impacts deep brain structures

Lacunar stroke

Less common type of stroke due to vascular tears and bleeds

Hemorrhagic stroke

Non-traumatic brain bleed in subarachnoid space from a ruptured saccular aneurysm (MC), malformed vessel, or tumor related vascular compromise; leads to loss of consciousness; >40 y.o.

Subarachnoid hemorrhage

Non-traumatic brain bleed from a small vessel rupture (microbleed) in brain parenchyma; MC cause due to chronic HTN

Primary brain parenchymal hemorrhage (intracranial hemorrhage)

High flow causing increase in arterial pressure and volume (increases risk of rupture and hemorrhage), tangles network of malformed or weakened vessels; causes intractable HA and onset of seizure activity; MC in males 10-30 y.o.

Arteriovenous malformation (AVM) - very dangerous

Hypertensive encephalopathy can occur due to a sustained diastolic BP of __ (severe ICP)

>130

Mild traumatic brain injury (mTBI), causing physical and mental symptoms:

• Physical - headache, nausea, dizziness, light and sound sensitivity, potential loss of consciousness

• Mental - decreased memory and cognition, irritability, depression, anxiety, personality change

Concussion

Decreased cognition, emotional dysfunction, headache, suicidal aggression

Tau proteins break down (normally stabilize microtubules in neurons)

Chronic traumatic encephalopathy

Movement of one brain region in relation to another; angular acceleration, causing “whiplash” (white matter damage from rapid stretch); may lead to severe dysfunction, coma, or death

Diffuse axonal injury

In __, injury occurs between cortex and red nuclei, causing brachial flexion

Decorticate rigidity

In __, injury occurs in brainstem between red nuclei and vestibular nuclei

Decerebrate rigidity

Traumatic brain bleed causing dural artery damage; associated with skull fracture and rapid compression of brain tissue (mass effect)

Epidural hematoma - very dangerous

Traumatic brain bleed from rapid movements that tear bridging veins and compress brain (infant and geriatric types)

Subdural hematoma

Infant version of subdural hematoma

“Shaken baby syndrome”

Geriatric version of subdural hematoma

Cerebral atrophy

What is the primary risk for neural tube defects?

Folate (B9) deficiency leading up to and during pregnancy

Hidden defect in vertebral column due to incomplete closure of posterior arch (MC in upper cervical and lower lumbar); generally asymptomatic or mild, tuft of hair or birthmark at site

Spina bifida occulta

Severe defect in vertebral column where cauda equina, meninges, and CSF protrude through defect (causes damage/compression to LMN - flaccid motor paralysis, impaired motor, sensory and bowel/bladder)

Myelomeningocele

Absence of brain matter, causing still birth or severe disability (if survives)

Anencephaly

Craniofacial abnormality of CSF and brain tissue that is variable in severity

Encephalocele

Cyst filled with CSF in the central canal, causing compression to anterior commissure (loss of pain and temperature - spinothalamic)

• Common in adults

• Due to type I chiari malformation

• Contraindication to chiropractic care

Syrinx (syringomyelia)

CSF filled cyst extended into 4th ventricle (congenital)

Hydromyelia

What is the MC and more mild type of chiari malformation?

Type I

Low-lying cerebellar tonsils malformation (~5mm extension of tonsils through foramen magnum); causes a headache which worsens with cough/strain

Type I chiari malformation

Downward extension of tonsils and vermis, small posterior fossa; very severe and fatal; found in utero or infants

Type II chiari malformation (Arnold-Chiari)

Deficiency of thiamine (B1) in the CNS causing necrosis to thalamus, confabulation, and ataxia; found in alcoholics

Wernicke-Korsakoff Syndrome

Deficiency of thiamine (B9) in PNS causing lower extremity paralysis

Beriberi

Deficiency in __ causes subacute combined degeneration of the SC

Cobalamin (B12)

Blood glucose <70mg/dL; global hypoxia symptoms

Hypoglycemic

Blood glucose <54mg/dL (severely low)

Severe hypoglycemic

Blood glucose >600mg/dL; long-term state causes dehydration

Hyperglycemic

Autoimmune demyelinating disorder in CNS, causing unilateral visual (optic nerve lesion), sensory and motor impairments (SC lesions, UMN - spastic weakness)

• Dx based on white matter plaques

• MC in young and middle aged women

Multiple sclerosis

Impaired memory and cognition which decreases function and ability to self care

Dementia

MC cause of dementia

Alzheimer disease

• Initial stage of forgetfulness, mild short-term memory issues

• Later stage of decreased language, learned motor, and cognition

• End stage of inability to care for self, bedridden

• Late onset (~85 y.o.)

• Amyloid precursor protein (APP) not removed → B-amyloid accumulates → intracellular Tau proteins destabilize neurons (cerebral and hippocampal atrophy)

Alzheimer disease