Head injury and SOL

Space occupying lesion

Focal damage Lacerations, haemorrhage in regional brain damage High/low velocity means large differences -pressure waves

• sudden acceleration of head so the brain moves inside the cranial cavity and makes contact with bony protrusions • RTAs, falls, assaults -primary injury (due to impact) secondary injury (evolves after primary injury and is potentially treatable)

scalp lesions Skull fractures surface contusions/lacerations diffuse axonal injury/diffuse vascular injury

-bruising Lacerations Bleeding Route for infection

-fissure fracture Depressed fracture Compound fracture base of skull fracture -higher incidence of intracranial bleeding

-lateral surface of hemispheres undersurface of temporal and frontal lobes -Coup: at point of impact Contracoup: diametrically opposite point of impact

• occurs at moment of injury: widespread disruption of axons due to shear and tensile strains affecting axons at the time of acceleration/decceleration • coma and vegetative state • GCS -Na channels normally centred around the nodes of ranvier, damage to axon causes redistribution of the Na channels along the length of the axon to demyelinated segments, get partial restoration of conduction There is an increased number and distribution to help restore conduction this increases energy needs of the neurones and so there is an energy failure leading to mitochondrial apoptosis Then get Ca influx and activation of calpains results in cytoskeletal disruption and disrupted integrate flow -prevent Na influx and reduce brain activity: medically induce a coma

trauma raised intracranial pressure progression of inflammatory disease progression of dementia hypoxia

extra dural intradural (subdural, subarachnoid, intracerebral/intracerebellar burst lobe)

• fracture in temparoparietal region that involves middle meningeal artery • midline shift, compression and herniation

• 5-13mmHg • if the brain enlarges and can no longer compensate then the venous sinuses are flattened and there is little or no CSF, any increase in rain size will result in rapid increase in ICP • blood and CSF escape form the cranial vault -focal lesion in the brain diffuse lesion in the brain increased CSF increased venous volume Physiological (hypoxia, hypercapnia, pain) -intracranial shifts and herniations distortion and pressure on CN and vital centres reduced level of consciousness impaired blood flow -papilloedema Nausea & vomiting headache Neck stiffness

• unilateral or asymmetric expansion of cerebral hemisphere displaces the cingulate gyrus under the falx cerebri. • medial aspect of temporal lobe (hippocampal uncus and parahippocampal gyrus) herniates over the tentorium cerebelli. – displacement of cerebellar tonsils through the foramen magnum (compresses brainstem) -a swollen brain will herniate through any defect in the dura and skull.

tumours Abscess Haematoma localised brain swelling E.g. around infarct

single: focal cause otitis media, sinusitis, nasal/facial/dental infection, skull fracture, penetrating injury, neurosurgical procedure Multiple: septicaemia usually acute bacterial endocarditis, bronchiectasis and lung abscess, cyanotic heart disease, IV drug abuse

-vasogenic (defect in BBB) -cytotoxic (due to ischaemia, intracellular changes) -hydrostatic (in hypertensive encephalopathy) -interstitial (in acute obstructive hydrocephalus, fluid is forced into periventricular white matter) -hypo-osmotic (swelling due to reduced serum osmolality)

-rupture of meningeal arteries and associated skull fractures -compress dura and flatten gyro crests of underlying brain -uncal gyro/cerebellar tonsillar herniation brainstem compression DEATH

• collections of blood between the internal surface of dura mater and arachnoid mater • Caused by disruption of bridging veins that extend from the surface of the brain into subdural space • over the cerebral hemispheres -acute (clothed blood) chronic (liquefied blood)

• trauma • other traumatic lesions • swelling of cerebrum on side of haematoma giving mass effect

• less often trauma • brain atrophy • liquefied blood, yellow tinged fluid separating from inner surface of dura meter and underlying brain by neomembrane -altered mental status focal neurological deficits