Nervous System Pathology

Monro-Kellie Hypothesis

Monro-Kellie Hypothesis

-A supposition that states the cranial cavity cannot be compressed, and the volume inside the cavity is fixed (normal intracranial pressure is 4-15 mmHg).

-The skull and its components create a state of volume equilibrium, such that any increase in volume of one component must be compensated by a decrease in volume of another component.

Cerebral Contusion

Acceleration-deceleration injury

Location of coup injuries

site of impact

Counter-coup injury location

opposite the site of impact

countercoup is most common in

frontal and temporal lobes

Cerebral contusion causes permanent damage to

-small blood vessels
-surface of brain

Major characteristic of an epidural hematoma

arterial bleed

location of epidural hematomas

-between bone and dura
(rarely crosses midline)

-middle meningeal artery

Cause of epidural hematoma

direct blow to head

Epidural hematoma pathogenesis

*middle meningeal artery tear
-blood between dura and bone
-increased intracranial pressure
-herniation (shift in brain tissue)
-death

How is an epidural hematoma diagnosed?

-CT

-Mass-effect on brain
(crescent-shaped)

Epidural hematoma treatment if minor

observation

Epidural hematoma treatment

Burr holes to relieve pressure

Major characteristic of subdural hematoma

Venous bleed

Location of subdural hematoma

between dura and arachnoid mater

causes of a subdural hematoma

-blunt trauma
-anticoagulation
-child abuse
-spontaneous

Subdural hematoma pathogenesis

tear in bridging veins between brain and dural sinuses
enlarging clot

-slow
-covers convexity of brain
-consciousness flunctuates
-herniation
-death

subdural hematoma diagnosis

-CT

-Mass effect:
A. midline shift
B. follows the shape of the brain

Subdural hematoma treatment

If minor -> observation
-Burr holes to relieve pressure

Hematomas: Epidural vs. Subdural

Traumatic Brain Injury (TBI)

Complex pathophysiologic process affecting the brain

-induced by traumatic biomechanical forces secondary to direct or indirect forces to the head

Hallmark of TBI

Diffuse axonal injury

Traumatic Brain Injury: 2 Phases

1. Diffuse axonal injury
-> rotational forces

2. Delayed phase
->inflammation, edema, ischemia
-free radicals, apoptosis

Pathophysiology of cerebrovascular diseases

Decreased blood supply/ oxygenation due to:
-hypoxia
-ischemia
-infarction

Global Hypoxic Injury underlying cause

lack of O2 to the brain

Global Hypoxic Injury causes

Cardiac arrest
Shock
CO poisoning
High altitudes
Choking
Stroke

Global Hypoxic Injury pathology

-Cerebral atrophy

-apoptosis of neurons

(known as red neurons)

-pyknotic nuclei

-spaces for apoptotic neurons

-laminar necrosis

Global Hypoxic Injury pathophysiology

-Watershed infarcts

-Blood distributions don't quite overlap

-Most common location = ant. + middle cerebral arteries

stroke

-loss of blood flow to an area of the brain

-specific neurologic deficits

Types of Strokes

-Ischemic

-Intracerebral hemorrhage

-Subarachnoid hemorrhage

-Lacunar stroke

most common type of stroke

ischemic (atherosclerotic)

Stroke diagnosis

-CT scan
(hemorrhagic vs. nonhemorrhagic)

-MRI to confirm

Stroke acute treatment

-thrombolytics if they qualify
-surgical evacuation of hemorrhagic strokes

Treatment for chronic strokes

-antiplatelets (ASA, clopidogrel)
-warfarin for embolic strokes
-treat underlying diseases

Thrombotic stroke pathogenesis

Platelet thrombosis over atherosclerotic plague

most common thrombotic stroke location

middle cerebral artery

thrombotic stroke locations

-middle cerebral artery

-Bifurcation of common carotid
(int. carotid artery)

-Basilar artery

Pale infarctions

-peripheral of cortex
-no hemorrhage

Swelling of brain

-loss of grey/white matter borders
-myelin breakdown

gliosis

-reaction to injury

-astrocytes proliferate

-microglial (macrophages) cells remove debris

Clinical findings for MCA thrombotic stroke

-contralateral hemiparesis
-sensory loss in face and UE
-Broca's aphasia
-visual defects
-head and eyes deviate toward lesion

Clinical findings for ACA thrombotic stroke

contralateral hemiparesis
sensory loss in LE

Clinical findings for Vertebrobasilar thrombotic stroke

vertigo
ataxia
ipsilateral sensory loss in face
contralateral hemiparesis
sensory loss in trunk and limbs

Thrombotic stroke clinical findings are _ dependent

location

Thrombotic strokes commonly precede a

TIA (ischemia w/o infarction)

Thrombotic stroke treatment

-Prevention:
(ASA, clopidogrel, statins)

-PT/OT

Embolic Stroke

Ischemic stroke due to embolus
(AKA -> hemorrhagic stroke)

Sources of emboli

1. left heart
2. atrial fibrillation
3. fat embolus
4. amniotic fluid
5. Tumor emboli (in cancer patient)

Embolic stroke common locations

-MCA
-Vessel reperfusion

Intracerebral Hemorrhage pathogenesis

-HTN causes stress on vessels

-Microaneurysms develop

-Aneurysms rupture

-Hemorrhage / hematoma

Intracerebral Hemorrhage location

basal ganglia (most common)
Thalamus
Pons
Cerebellum

Subarachnoid Hemorrhage causes

Rupture of a berry aneurysm (most common)

AV malformation

Berry aneurysm risk factors

-Normal hemodynamic stresses
-HTN
-Coarctation of aorta
-Atherosclerosis
-Smoking

Berry aneurysm locations

-Communicating branches with main cerebral artery

-Anterior communicating branch (Most common)

Rupture of a berry aneurysm causes a

subarachnoid bleed
(blood covers surface of brain)

berry aneurysm clinical findings

***Worst headache of their life

(thunderclap headache)

-50% mortality

-CSF becomes yellow: AKA: xanthochromia

(Bilirubin from breakdown of RBC's)

Lacunar Infarcts pathogenesis

Arteriosclerosis

Lacunar Infarcts most common cause

Hypertension

Neural tube defects

-birth defects in brain, spine & sp. Cord
-due to improper circulation

Anencephaly

absence of most of brain

Spina bifida

fetal spinal column doesn't close

Meningocele

herniation of meninges through spinal column defect

Neural tube defects can be prevented with

folic acid

hydrocephalus pathology

too much CSF within skull

2 classifications of hydrocephalus

1. Communicating = too much CSF

2. Noncommunicating = obstruction of CSF flow

Hydrocephalus: infant Clinical Manifestations

large head
rapid increase in head size
bulging fontanelles
vomiting
lethargy
irritability
high-pitched cry
seizures
developmental delays

Hydrocephalus: older kids/adult Clinical Manifestations

headache
nausea / vomiting
vision issues
sluggish pupils
problems with balance, coordination or gait
extreme fatigue
slowing or regression of development
confusion
irritability
personality, memory, cognition changes

Hydrocephalus diagnosis

Exam:
-head circumference
-neurologic exam

Imaging:
-prenatal US, CT head, MRI, skull x-ray, cranial US

hydrocephalus treatment goal

minimize brain damage (by decreasing CSF flow)

hydrocephalus treatment

*Surgery

placement of shunts:
ventriculoperitoneal
ventriculoatrial

Leading cause of childhood disability in the US

Cerebral Palsy

(Group of disorders that appear in infancy or early childhood)

Cerebral palsy permanently affects

1. motor movement
2. muscle coordination
3. cerebral function (cognition & communication)

cerebral palsy is most commonly due to

damage to the cerebellum during birth or prenatal

Risk factors / contributing factors for cerebral palsy

prematurity
low birth weight
breech births
multiple fetuses
hypoxia
hypoglycemia
cerebral hemorrhage
neurologic infections
head injury
maternal infections
maternal toxin exposure

Clinical manifestations of cerebral palsy

persistence of early reflexes
developmental delays
ataxia
spasticity
flaccidity
hyperreflexia
asymmetrical gait
unusual limb positioning
tremors
difficulty with precise movements
balance and coordination issues
scoliosis

Cerebral Palsy diagnosis

-exam
-head CT and / or MRI
-EEG
-vision screen
-hearing screen

Cerebral palsy treatment

-muscle relaxants
-antiseizure meds
-pain management
-PT / OT
-assistive devices
-surgery to relieve contractures

Arnold-Chiari Malformation

medulla & cerebellum extend through foramen magnum

Platybasia

flat skull

Arnold-Chiari Malformation treatment

decompression

Dandy-Walker Malformation

partial or complete absence of the cerebellum

-Leads to dilation of 4th ventricle

-Noncommunicating hydrocephalus

Dandy-Walker Malformation treatment

shunt

Syringomyelia

-cyst within spinal cord (fluid filled)

*Leads to cloak-like distribution of loss of pain and temp sensation

Neurofibromatosis

Two types NF1 and NF2

Neurofibromatosis clinical findings

-Disordered growth of ectodermal tissue

-Tumors or malformations of the CNS

Most common demyelinating disease

Multiple Sclerosis

Multiple Sclerosis pathogenesis

-CD4 TH1 and TH17 cells react against myelin antigens

-CD4 TH1 cells secrete interferon to activate macrophages (releases TNF)

-TH17 cells secrete cytokines to recruit neutrophils and monocytes

-WBC and TNF attack myelin and oligodendrocytes

-demyelination occurs

-antibodies created to continue process

MS gross pathology

demyelinating plagues in white matter

MS histopathology

inflammatory infiltrate

MS symptoms

sensory dysfunction
UMN disease
muscle spasms
spasticity
weakness
fatigue
optic neuritis
scanning speech

MS treatment

DMARDs
symptomatic tx

MS diagnosis

MRI

Amyotrophic Lateral Sclerosis

AKA: ALS or Lou Gehrig's disease

ALS involves

damage to UMN + LMN

ALS does not involve

-sensory neurons
-cognitive function
-CN III, IV, or VI

Possible causes of ALS

-Increased glutamate levels
-Free radical damage

Early clinical manifestations of ALS

footdrop
LE weakness
hand weakness or clumsiness
muscle cramps / twitching

later symptoms of ALS

paralysis
respiratory failure
difficulty swallowing
difficulty chewing

ALS diagnosis

-EMG
-muscle biopsy
-lumbar puncture with CSF testing

ALS treatment

NO CURE!!!

-some meds will slow progression

-symptomatic meds -> Rilutek

-PT / OT

-therapy