เอกสารประกอบการสอน pathophysio neuro.ppt · brain herniation...
TRANSCRIPT
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PATHOPHYSIOLOGY OF THE NERVOUS SYSTEM
Peerayut Sitthichaiyakul, M.D. Department of Pathology, Faculty of Medicine, Naresuan University
NERVOUS SYSTEM
Central nervous system • Brain • Spinal cord Peripheral nervous system • Cranial nerves • Spinal nerves Autonomic nervous system
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CONTENTS
• Central nervous system
• Peripheral nervous system
Central Nervous System
• Mechanism of brain injury • Traumas • Cerebrovascular diseases • CNS infection • Degenerative diseases • Brain tumors
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MECHANISM OF BRAIN INJURY
• Occur in most form of acute brain injury • Oxygenated blood < metabolic demand • Ischemia Inability to generate ATP • Oxygen free radicals, excitary amino acids
and inflammatory cells 2° injury
Cellular Hypoxia and Ischemia
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Cerebral Edema • Vasogenic edema : damage of blood-brain
barrier increase vascular permeability intercellular edema – Cerebral infarction – Intracerebral hemorrhage – Brain tumor – Infection : meningitis, encephalitis, brain
abscess – Trauma – Lead poisoning
• Cytotoxic edema: intracellular accumulation – Hypoxia : cardiac arrest – Hyponatremia – Hemodialysis – Diabetic ketoacidosis
• Interstitial edema: periventricular edema
– Hydrocephalus
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Increased Intracranial Pressure
• ICP is exerted by the contents of the cranium
1. brain tissue 2. cerebrospinal fluid (CSF) 3. blood
• Common cause of increased intracranial pressure – Increased brain tissue volume: tumor hemorrhage infection – Increased cerebrospinal fluid volume hydrocephalus – Increased blood volume increased right atrial pressure
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Brain Herniation
Subfalcine herniation • cingurate lobe of the cerebral hemisphere
herniate through the space between falx cerebri and corpus callosum
• Compress anterior cerebral artery
Uncal herniation • Medial aspect of the temporal lobe herniate
over the edge of the tentorium cerebelli • Compress posterior cerebral artery • Compress brain stem brain stem
hemorrhage
Tonsillar herniation • Cerebellar tonsil herniate through the
foramen magnum • Compress medulla oblongata respiratory
center
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Hydrocephalus
• Noncommunicating hydrocephalus • Congenital malformation • Tumor • Inflammation • Hemorrhage
• Communicating hydrocephalus • Subarachnoid hemorrhage • Meningitis • Metastasis to subarachnoid space
TRAUMA
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Skull Fracture
• Linear fracture
• Depressed fracture
• Comminuted fracture
• Diastatic fracture
• Compound fracture
• Location – Fall while alert occipital region – Fall whlie loss of consciousness : syncopal
attack frontal region
• Clinical finding – Asymptomatic – Lower cranial nerve or cervicomedullary
dysfunction – CSF discharge fome nose or ear route of
organisms to meninges
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Traumatic Vascular Injury
• Epidural hematoma • Subdural hematoma • Subarachnoid hemorrhage
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Epidural hematoma
• Associated with skull fracture • Bleeding from middle minigeal artery • Bleeding into space between periosteum and dura Clinical findings • < 30 ml. asymptomatic • 30-50 ml. space-occupying lesion increased intracranial pressure compress venous sinus circulatory stagnation cerebral ischemia and edema brain herniation • > 60 ml brain herniation
Subdural hematoma
• Bleeding from bridging vein • Bleeding between dura mater and arachnoid layer • Acute subdural hematoma • Chronic subdural hematoma Clinical findings • Asymptomatic • Stretching of the meninges headache • Irritation of the cortex seizure • Growth of fibroblasts and hyalinized connective
tissue rebleeding chronic subdural hematoma
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Subarachnoid hemorrhage • Bleeding between arachnoid layer and pia mater • Traumatic subarachnoid hemorrhage bleeding
from bridging vein • Other cause
– Ruptured berry aneurysm : most common cause • Ruptured occur at any time • ⅓ associated with acute increase in intracranial
pressure – Ruptured arteriovenous malformation
CEREBROVASCULAR DISEASES
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• Third leading cause of death • Leading cause of serious disability • Risk factors:
– Hypertension – Diabetes mellitus – Hyperlipidemia – Cigarette smoking – Advancing age – Family history
• Two process depend on pathophysiology 1. Ischemia and infarction - Global cerebral ischemia/infarction hypoxic encephalopathy - Focal cerebral ischemia/infarction obstruction of local blood
supply 2. Hemorrhage
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Global cerebral ischemia (hypoxic/ischemic encephalopathy) – Shock – Cardiac arrest – Severe hypotension
• Survive vegetative state – Severe impaired neurologic function, coma
Cerebral Infarction
Focal cerebral ischemia 1. thrombosis 2. embolism • Thrombosis
– Atherosclerosis – Arteritis from syphilis, TB, Toxoplasma, CMV – Collagen-vascular diseases – Hematologic diseases with hypercoagulable
states – Drug abuse
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• Embolism – Cardiac mural thrombi: most common cause myocardial infarction valvular heart diseases atrial fibrillation – Atheromatous plaque – Paradoxical emboli – Emboli associated with cardiac surgery – Tumor emboli – Fat emboli – Air emboli
Clinical features • Neurologic deficit • Depend on
– Site of obstruction – Size of infarction Small cerebral infarction asymptomatic focal neurologic deficit Large cerebral infarction cerebral edema brain herniation
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• Hypertension : the most common cause arteriosclerosis of blood vessels small microaneurysm location of hematoma : basal ganglia,
internal capsule, thalamus, cerebellum and pons
• Other cause: tumor, vascular malformation, vasculitis, coagulative disorder
Spontaneous Intracerebral Hemorrhage
CNS INFECTION
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Route of entry for organisms 1. Hematogenous spreading: most common
route 2. Direct implantation 3. Local extension 4. Spread via peripheral nervous system
Meningitis
• Bacteria: most common origin adult Streptococcus, Neiseria children Hemophilus newborn E.coli, Group B Streptococci • Virus • Fungus • Parasite
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• Reach the CNS by hematogenous route or extension from adjacent site
• Headche, fever, stiff neck and signs of cerebral dysfunction
• Diagnosis lumbar puncture • ↑ neutrophils • ↓ glucose level • ↑ protein level
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• An inflammation of the brain parenchyma • Virus are the most often pathogen
Arbovius encephalitis Japanese B encephalitis Western equine encephalitis animal normal host human accidental host
Encephalitis
Herpes simplex encephalitis type 1 adult infected by direct contact
nerve ganglion encephalitis type 2 newborn acquire the organisms
from birth canal encephalitis • Bacteria, fungus, parasite
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Brain Abscess
• Localized collection of pus within the brain parenchyma
• Most common organism bacteria streptococci staphylococci anaerobes
DEGENERATIVE DISEASES
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• Cerebral cortex – Alzheimer disease – Pick disease
• Basal ganglia and brain stem – Parkinson disease – Huntington disease
• Motor neurons – Amyotrophic lateral sclerosis (motor neuron
disease)
• Most common cause of dementia • Aβ critical molecule in the pathogenesis of the
disease • Aβ peptide are derived from amyloid precursor
protein (APP) on the cell surface • APP are cleaved by secretase Aβ peptide
endocytosis aggregate Aβ fibrils • Aβ neurotoxic cellular response
oxidative damage
Alzheimer Disease
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Clinical findings • Symptomatic cause running more than 10
year • Forgetfullness • Dementia : gradual loss of memory and
cognitive function • Incontinent, mute, unable to walk • Bedridden • Pneumonia death
Parkinson Disease
• Second most common neurodegenerative disease
• Degeneration of dopaminergic neurons in substantia nigra
• Cause idiopathic • Movement disorders
– ↓ voluntary movement – ↑ involuntary movement
• 10-15% dementia
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BRAIN TUMORS
• Incidence 10-17:100,000 • Unique characteristic
– Distinction between benign and malignant is less evidence : benign tumor may be poor prognosis
– Limitation of surgical resection without neurologic deficit
– Anatomic site of the tumor can have lethal consequence
– Pathway for spread is subarachnoid space, rarely metastasize outsize the CNS
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Clinical signs and symptoms • Primary effect
– Location – Size increase intracranial pressure
• Secondary effect – Edema – Disturb cerebrospinal fluid drainage
hydrocephalus – Herniation
WHO classification 1999 • Tumors of the neuroepithelial tissue
– Astrocytic tumors astrocytoma glioblastoma (multiforme) – Oligodendroglial tumors oligodendroglioma – Ependymal tumors ependymoma
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• Tumor of cranial and peripheral nerve – Schwannoma – Neurofibroma
• Tumors of the mininges – Meningioma
• Tumors of the sellar region – craniopharyngioma
• Metastasic tumor
Glioblastoma (multiforme) : GBM • Most severe glial cell tumor • Most frequent brain tumor • Peak incidence between 45-70 yrs • Cerebral hemispheres • Seizure, headache, neurological deficit
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Metastasic Tumors • 50% of intracranial tumors • Five most common primary site:
– Lung – Breast – Skin (maligant melanoma) – Kidney – Gastrointestinal tract
• Extensive cerebral edema increased intracranial pressure
Neurocutaneous syndromes
• Group of inherited disease • Autosomal dominant • Multiple harmatomas or neoplasms,
particular CNS and skin Neurofibromatosis type I, type II Tuberous sclerosis von Hippel-Lindau disease
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Neurofibromatosis type I • 1:3,000 • Neurofibromas • Gliomas of optic nerve • Pigmented nodule of iris (Lisch nodules) • Cutaneous hyperpigmented macules (café
au lait spots)
Peripheral Nervous System
• Inflammatory (immune-mediated) neuropathies
• Traumatic neuropathies
• Tumors of the peripheral nervous system
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INFLAMMATORY NEUROPATHIES
Acute inflammatory demyelinating poly-radiculoneuropathy (Guillain-Barré syndrome)
• Acute and subacute paralytic illness • Ascending paresthesia and paralysis (from leg to
arm) bedridden respiratory failure • Autoimmune diseases • Associated with viral infection or another
immunologic stimulus
TRAUMATIC NEUROPATHY
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• Laceration • Avulsion • Compression neuropathy (Entrapment
neuropathy) – Carpal tunnel syndrome Predisposing factor Inflammatory arthritis Excessive use of wrist joint Amyloidosis Pregnancy Hypothyroidism
TUMORS OF THE PNS
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• Neuronal origin neuroblastoma • Nerve sheath origin neurofibroma schwannoma (neurilemmoma) malignant peripheral nerve sheath
tumor (malignant schwannoma)
Schwannoma • Arise from Schwan cell • Associated with neurofibromatosis II • In cranial cavity cerebellopontine angle
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Neurofibroma • Solitary neurofibroma
• Peripheral nerve • Skin cutaneous neurofibroma • Associated with NFI
• Plexiform neurofibroma • Associtaed with NFI