CENTRAL NERVOUS SYSTEM PATHOLOGY

1. CENTRAL NERVOUS SYSTEM PATHOLOGY

2. CONGENITAL ANOMALIES OF CNS

3. Anencephaly: • Basically a complete absence of the cerebral hemispheres.

4. Anencephaly

5. Encephalocele and Cranial Meningocele: • Consists of a protrusion of brain or meninges through a cranial defect. • Most frequent in the occipital region.

6. Cranial Meningocele

7. Spinal Meningeocele • Meningeoceleconsists of herniation of both dura and arachnoid ( layer containing the blood vessels) through a vertebral defect, with the spinal cord remaining in its normal position.

8. Spinal Meningeocele

9. Hydrocephalus • Definition: • This is a chronic accumulation of CSF inside the ventricular system leading to its dilatation and consequently atrophy of the brain tissue

10. Hydrocephus

12. Etiology: • Increased CSF production: due to choroids plexus papilloma • Obstruction of CSF flow: due to: • Congenital causes (non-communicating type of obstructive hydrocephalus due to congenital narrowing of ventricular foramina or aqueduct • Acquired causes: • Meningitis • Brain tumor or brain abscess

13. 3. Decreased CSF absorption due to: • Congenital causes: congenital aplasia of the arachnoid villi (lining the ventricles) • Acquired causes: damage of archnoid villi in case of meningitis • Thrombosis of superior sagittal sinus

14. Pathology: • There is ventricular dilatation with excess CSF • In infants, hydrocephalus leads to enlargement of the head due to separation of skull sutures • In adults, hydrocephalus leads to increased intracranial tension which may lead → brain herniation → death

15. A hydrocephalus MRI scan and a normal MRI scan

16. Cerbro-vascular disease of CNS

17. Cerebral ischemia • Cerebral infarction • Cerebral hemorrhage

18. Cerebral ischemia: • Definition:Decrease in blood flow to the brain • Etiology: shock, • hypotension, • cardiac arrest • Types: • Generalised cerebral ischemia: usually causes irreversible damage of brain tissue • Transient ischemic attack: usually there is reversible symptoms

19. Cerebral infarction: • Etiology: • Thrombotic occlusion: due to atherosclerosis and it leads to anemic white infarction • Embolic occlusion: due to thrombo-emboli from cardiac chambers and it leads to hemorrhagic infarction • Small vessel diseases: related to hypertension and arteriosclerosis, it leads to lacunar infarction i.e. lacunae (multiple small infarctions)

21. EMBOLIZATION OF CEREBRAL ARTEY

22. Acute infarction of brain Lacunar infarction Intermediate infarction Old infarction

23. Cerebral hemorrhage: • Classified as: • Intracerberal hemorrhage • Epidural hemorrhage • Subdural hemorrhage • Subarchnoid hemorrhage

24. Intracerberal hemorrhage (intraparenchymal) • Hypertension is the most frequent predisposing condition. • Other causes as: • vascular malformation especially arteriovenous malformations, cerebral angiopathy, neoplasms, vasculatides, abnormal hemostasis, hematological malignancies and infections

25. Vascular malformations

26. Clinically: • Severe headache • Frequent nausea and vomiting and progression of symptoms to coma

27. Intracerberal haemorrhage (intra parenchymal)

28. Epidural hemorrhage • Always traumatic • Usually associated with skull fracture • Tear of dural arteries most frequently occurs in the middle meningeal artery • Usually leads to cerebral herniation • Lucid interval before loss of consciousness (short loss of consciousness then patient is well then coma)

29. Epidural hemorrhage

30. Sub-dural hemorrhage • Usually traumatic in old age • Slow haemorrhage • Gradual symptoms • Caused by rupture of bridging veins (from cerebral to sagittal sinuses) • Predisposing conditions: brain atrophy and abnormal haemostasis • Clinically: • Headache, drowsiness, focal neurological deficits and sometimes dementia

31. Sub-dural hemorrhage

32. Subarachnoid hemorrhage • Most frequent cause is ruptured berry aneurysms as well as trauma, abnormal haemostasis (blood diseases) and tumours • Clinically: • There is sudden thunderclap headache, nuchal rigidity, neurological deficits on one side and stupor

33. Sub arachnoid hemorrhage

34. Diffuse sub-arachnoid haemorrhage

35. BERRY ANEURYSMS • Definition: • Thin-walled saccular out-pouchings of blood vessels with thinning of the vessel wall • Most frequent cause of subarchnoid haemorrhage • Most frequent site is the anterior circle of Willis at the branching points

36. BERRY ANEURYSMS

37. Causes of rupture: • 1-increased blood pressure • 2-trauma • 3-spontaneously

38. Complications: • Sub arachnoid haemorrhage due to rupture • Thrombosis • Pressure on the surrounding structures

39. CNS TRAUMA

40. CNS TRAUMA • Trauma of cranial cavity and brain • Brain Concusion • Brain contusion • Diffuse axonal injury • Trauma of spinal cord • Cerebral herniation • Sub-falcine (cingulated gyrus) • Transtentorial (uncal) • Cerbellar tonsillar

41. A- Trauma of the cranial cavity and brain • Brain concusion: • Change in the momentum of the head (impact against a rigid surface) • Loss of consciousness and reflexes, temporary respiratory arrest and amnesia for the event

43. Brain contusions: • Impact of parts of brain against inner calvarias surfaces • Bruising of the brain resulting from tissue and vessels disruption • Site of injury: crests of orbital gyri in frontal and temporal poles

45. Pathology: • Coup: (site of injury) and countercoup: site diametrically opposite • Coup and countercoup develop when the head is mobile • Clinically: • Acute: hemorrhage of brain tissue in a wedge- shaped area • Subacute: necrosis and liquefaction of brain • Remote: depressed area of cortex with yellow discoloration

47. Coup and countercoup

48. OLD BRAIN CONTUSION

49. Diffuse axonal injury: • Injury to the white matter due to acceleration/ deceleration • Damage to the axons • Usually there is coma after the trauma