8/31/2011 1 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
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
8/31/2011
1
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
• 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
8/31/2011
4
Cerebral Edema • Vasogenic edema : damage of blood-brain
• 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
8/31/2011
11
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
8/31/2011
12
• 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
8/31/2011
13
Global cerebral ischemia (hypoxic/ischemic encephalopathy) – Shock – Cardiac arrest – Severe hypotension
• Survive vegetative state – Severe impaired neurologic function, coma
– Atherosclerosis – Arteritis from syphilis, TB, Toxoplasma, CMV – Collagen-vascular diseases – Hematologic diseases with hypercoagulable
states – Drug abuse
8/31/2011
14
• 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
8/31/2011
15
• 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
8/31/2011
16
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
8/31/2011
17
• Reach the CNS by hematogenous route or extension from adjacent site
• Headche, fever, stiff neck and signs of cerebral dysfunction