NEUROPATHOLOGY.ppt

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  • 1. NEUROPATHOLOGY
    • INTRACRANIAL HYPERTENSION CSF pressure is pulsatile at 2 frequencies: *Synchrony with beat by beat change of intracranial blodd volume *Synchrony with respiration (at a slower fre quency as result from changes in intrathora- cic and central venous pressure)
  • 2. NEUROPATHOLOGY
    • INTRACRANIAL HYPERTENSION(cont) *Normal CSF pressure: -0-140 mm H2O(0-10mmHg=0-1.3kPa) *Intracranial hypertension(ICP): >200 mm H2O (15 mmHg =2kPa) *SLOW elevations up to 200-300 mmH2O (15-22.5 mmHg = 2-3 kPa) may be well tole rated in patients with intracranial expanding lesions
  • 3. NEUROPATHOLOGY
    • INTRACRANIAL HYPERTENSION(cont) *Values up to and above 500 mmH2O(37.5- 38 mmHg or 5 kPa) are associated with sig nificant cerebral edema *ICP >800 mmH2O (60 mmHg or 8 kPa) is almost always a prelude to death in patients with expanding lesions or head injury
  • 4. NEUROPATHOLOGY
    • INTRACRANIAL HYPERTENSION(cont) Increased intracranial pressure occurs in 2 main circumstances: 1. Due to the presence of an EXPANDING LESION A.Intracerebral(hemorrhages/hematomas, traumatic or spontaneous; infarction and tumors) B.Meningeal(hemorrhages/hematomas, usually traumatic: extradural, subdural or subarach noidal; tumors vgr. Meningiomas)
  • 5. NEUROPATHOLOGY
    • INTRACRANIAL HYPERTENSION(cont) Complications of raised ICP: *Reduced cerebral flow -due to reduced cerebral perfusion pressure *Intracranial herniation
  • 6. NEUROPATHOLOGY
    • INTRACRANIAL HYPERTENSION(cont) Clinical symptoms and signs: -headache -nausea and vomiting -diplopia -papilledema -focal neurologic signs related to intracranial expanding lesions or brain shifts w/herniation -alteration in level of consciousness
  • 7. NEUROPATHOLOGY
    • CEREBRAL PERFUSION PRESSURE *This is the difference between arterial and intracranial pressure *Compensatory arterial/arteriolar vasodilation mantain cerebral flow AUTOREGULATION -Effective only in conditions of mild to moderate reduction in CPP *CPP =zero= brain death *Intracranial hypertension(CSF pres >200mmH2O and brain edema commonly occur together BUT DO NOT neccesarily coexist
  • 8. NEUROPATHOLOGY
    • CEREBRAL ISCHEMIC THRESHOLDS Cerebral blood flow(ml./100 g/min) * 50-60 - normal * 20-25 - alteration in level of conscious ness and abnormal EEG *18-20 - isoelectric EEG and neurotransmi tter failure *12-16 – loss of evoked potential and Na+/ K+ pump failure
  • 9. NEUROPATHOLOGY
    • CEREBRAL ISCHEMIC THRESHOLDS... *10-15 - Ion pump failure and cytogenic (cytotoxic)edema *>10 – Ca++ chanels open, activation of intracellular enzymes and cellular membra ne alterations
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  • 15. NEUROPATHOLOGY
    • CEREBROSPINAL FLUID(CSF) Appearance thin,clear and colorless Coagulation No Blood or RBC No Cell count Mononuclear<5/ml Glucose 60% of serum level Proteins <45 mg/dL
  • 16. NEUROPATHOLOGY
    • HYDROCEPHALUS *Is the enlargement of the ventricles with increase in the volume of CSF *Usually associated with increased CSF pre ssure *It is required shunting procedures to relieve pressure
  • 17. NEUROPATHOLOGY
      • CLASSIFICATION: *Communicating(increased production of CSF or decreased absorption by arachnoi dal granulations) *Non-communicating(obstructive),conge nital or acquired *Hydrocephalus ex vacuo
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  • 20. NEUROPATHOLOGY
    • HYDROCEPHALUS...(cont.) CAUSES: *CSF overproduction, vgr. choroid plexus papilloma, Arnold-Chiari malformation *Failure of absorption by arachnoidal granu lations e.g. Post-meningitic leptomeningeal fibrosis, duramater sinus thrombosis, abnor mal arachnoidal granulations.
  • 21. NEUROPATHOLOGY
    • HYDROCEPHALUS...(cont.) CAUSES... *Congenital stenosis or atresic aqueduct *Obstruction of 3rd ventricle/aqueduct by cysts or neoplasia, gliosis/chronic inflamm. of aqueduct, obstruction of 4th ventricle, or ganized subarachnoidal hemorrhage w/obs truction at the base of encephalus.
  • 22. NEUROPATHOLOGY
    • HYDROCEPHALUS...(cont.) CAUSES... Compensatory expansion of the ventricles secondary to brain atrophy e.g. Alzheimer´s disease (hydrocephalus ex vacuo)
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  • 24. NEUROPATHOLOGY
    • HYDROCEPHALUS...(cont.) CAUSES... *Obstruction -at level of foramen of Monro-tumors -aqueduct-congenital stenosis,postinflamm., midbrain tumors -4th ventricle-intraventricular,cerebellar and brainstem tumors -foramina of Luschka and Magendie-postmeningitic fibrosis, posterior fossa tumors
  • 25. NEUROPATHOLOGY
    • HYDROCEPHALUS...(cont.) NORMAL PRESSURE HYDROCEPH. *It is a distinct clinical entity characterized by dementia, gait disturbance and urinary incontinence. *CSF pressure is normal
  • 26. NEUROPATHOLOGY
    • INTRACRANIAL HYPERTENSION
    • *Intracranial hypertension(CSF pressure> 200 mm H2O) and brain edema commonly occur together BUT DO NOT necessarily coexist.
  • 27. NEUROPATHOLOGY
    • Changes associated w/intracranial expanding lesions:
    • *Local deformity
    • *Collapse of ventricles -initial spacial compensation by reduction in CSF volume
    • *Shift and brain distortion
    • *Internal herniations
  • 28. NEUROPATHOLOGY
    • SULFACINE HERNIATION
    • *Herniation under the falx – mainly involving the cingulate gyrus -anterior cerebral artery occlusion leading to infarction of paracentral lobule -spastic paralysis and a cortical sensory disorder in the contralateral leg
  • 29. NEUROPATHOLOGY
    • SULFACINE HERNIATION...(cont.) *Clinical: *Complications -Headache -Ipsilat.ACA infarct -Contralat.leg if ACA is entrapped weakness under the falx -Assoc.herniation
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  • 34. NEUROPATHOLOGY
    • TRANSTENTORIAL HERNIATION
    • *It occurs often as result of shift of supratentorial structures through the incisura tentorii
    • *The anatomic structures compressed during the shift include: -ipsilateral oculomotor nerve – pupil dilated with poor or no light reflex
  • 35. NEUROPATHOLOGY
    • TRANSTENTORIAL HERNIATION... -uncal herniation
    • * occlusion of posterior cerebral artery
    • * hemorrhagic infarction of temporal and occipital(including calcarine cortex) cortices
    • -compression of contralateral cerebral peduncle(Kernohan´s notch) leading to ipsilateral hemorrhage
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  • 44. NEUROPATHOLOGY
    • TRANSTENTORIAL HERNIATION... *Midbrain compression and hemorrhage (Duret) involving midbrain and tegmentum of the pons will produce loss of consciousness and decerebrate rigidity
  • 45. NEUROPATHOLOGY
    • DESCENDING TRANSTENTORIAL HERNIATION. *Clinical: *Complications: -Ipsilateral dil.pupil -Occipital infarct -Contralateral hemipar. (comp. of ACA) -Ipsilat.hemipar.if there is Kernohan Notch
  • 46. NEUROPATHOLOGY
    • ASCENDING TRANSTENTORIAL HERNIATION. *Clinical: *Complications: -Nausea -Hydrocephalus -Vomiting -Rapid onset of -Obtundation obtundation  death
  • 47. NEUROPATHOLOGY
    • FORAMEN MAGNUM(TONSILLAR) HERNIATION. *Associated with expanding supratentorial or infratentorial masses *Characterized by: -cerebellar tonsillar herniation and necrosis -compression of the pyramids  motor signs -compression of RAS  changes in level of consciousness -compression of cardiac/respiratory centers  sudden cardiac/respiratory failure
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  • 51. NEUROPATHOLOGY
    • TONSILLAR HERNIATION... *Clinical: *Complications: -Bilateral arm dysesthes. -Obtundation  -Obtundation death
    • *Imagin findings: -Cerebellar tonsils 5 mm below foramen in adults and 7 mm in children