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CNS PATHOLGY

CEREBROVASCULAR ACCIDENTS (strokes) non-traumatic cerebrovascular accident of abrupt onset. a common cause of death and disability, accounting for ~ 80,000 deaths/year UK 3rd leading cause of death after myocardial infarction and cancerCommon complication of atherosclerotic and hypertensive arterial disease.

AETIOLOGYCerebral thrombosis (resulting from atherosclerotic arterial disease) with infarction is responsible for about 90% of cases. Involve the LARGE ARTERIES AND SITES OF ARTERIAL BIFURCATION (eg carotid bifurcation) and CURVATURE (eg carotid siphon in the petrous temporal bone). Cerebral embolism is usually from the heart (after myocardial infarction, infective endocarditis, prosthetic heart valves).

PATHOLOGY After 6h softening of the brain occurs with loss of the normal DEMARCATION between grey and white matter.

MICROSCOPY NEURONAL NUCLEAR PYKNOSIS, CYTOPLASMIC EOSINOPHILIA AND LIQUEFACTION. Glial cells disappear + myelin sheaths and axon cylinders in the white matter disintegrate. 48-72h Formation of the cerebral infarct is fully complete. A pale soft area composed of liquefied necrotic cells 3 weeks removal of debris produces cystic fluid-filled cavity surrounded by reactive GLIOSISGood prognosis Improv. Occurs with T. Physical therapy important.

CRANIAL TRAUMA major problem in road traffic accidents and is responsible for many deaths in the 10 -30y age group.

CEREBRAL INJURIES PENETRATING (OPEN) INJURIES Gunshots + severe blunt trauma. Severe brain damage and incidence of infection NONPENETRATING (CLOSED) INJURIES blunt trauma = CEREBRAL CONCUSSION, (transitory loss of cerebral function including loss of consciousness). CEREBRAL CONTUSIONS (areas of subpial haemorrhage due to rupture of small blood vessels in the surface of the brain. ) + CEREBRAL LACERATIONS (tears in the cerebral tissue.)SPINAL CORD injuries result from forced movements (eg “whiplash” injury of cervical cord) or vertebral fractures.

TRAUMATIC INTRACRANIAL HAEMORRHAGE ACUTE EXTRADURAL HAEMATOMA accum of blood between the skull and dura (90% of cases are due to bleeding from a branch of the middle meningeal artery, often associated with a temporal fracture). Treatment is surgical evacuation of the blood clot.

CHRONIC SUBDURAL HAEMATOMA accum of blood in the subdural space, separated from the brain by the arachnoid and subarachnoid space. Bleeding results from rupture of veins passing from the cerebral cortex to the superior sagittal sinus. Occurs mainly in elderly patients with some degree of cerebral atrophy. Trauma required is minimal. Treatment by surgical evacuation of the fluid collection is curative.

CEREBRAL INFECTIONS BACTERIAL and VIRAL MENINGITIS are common infections of the CNS

CEREBRAL INFECTIONS RELATED TO AIDS - in prevalence. CEREBRAL TOXOPLASMOSIS - multiple necrotic lesions (0.5-3 cm) caused by a protozoan parasite that has its definitive cycle in the intestine of cats. Humans become infected through contact with cat faeces containing infective forms of the parasite. CYTOMEGALOVIRUS ENCEPHALITIS HERPES SIMPLEX ENCEPHALITIS. (Herpes virus encephalitis viral inclusions in neurone nuclei)

AETIOLOGY Many types of bacteria cause brain abscesses. Several organisms may occur in a single abscess. Anaerobes are common.Abscesses arise from oral bacteria (particularly Streptococcus milleri) and, less commonly, as a complication of other diseases ( eh. Chronic suppurative ear infections, Infective endocarditis, Suppurative lung diseases.)

CEREBRAL ABSCESS localised area of suppurative inflammation in the brain substance. The cavity contains thick pus (formed from necrotic, liquefied brain tissue and many neutrophils).

ALZHEIMER’S DISEASE cause unknown. Evidence of transmission of an autosomal dominant age- dependent trait in some families - may be related defects or duplications of the chr21 gene encoding the -amyloid protein of Alzheimer’s disease. Down’s syndrome who survive to adulthood show Alzheimer-like disease.

DEGENERATIVE DISEASE (CEREBROCORTICAL DEGENERATION) results in the clinical picture of dementia. Dementia loss of higher cortical functions (loss of ability to solve problems, agility of thought processes, and emotional lability) which progresses inexorably to a stage where daily