Fwd: Head injury Bambury

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Date: 2009/2/25
Subject: Head injury Bambury
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Fwd: Head injury Bambury

  1. 1. Head Injury Niamh Bambury Lecturer in Surgery 18/09/08
  2. 2. Introduction <ul><li>Head trauma results in approximately 70,000 deaths, 80,000 long-term disabilities, and 60,000 new seizure disorders each year </li></ul><ul><li>These injuries most often occur in individuals who are 15-24 years old and are twice as common in men </li></ul><ul><li>Causality is bimodal </li></ul><ul><ul><li>vehicular accidents being most common in those under 25 years </li></ul></ul><ul><ul><li>falls in those over 75 years </li></ul></ul><ul><li>Nearly half involve intoxication with drugs or alcohol </li></ul>
  3. 3. Anatomy <ul><li>Scalp </li></ul><ul><li>Structure of the brain </li></ul><ul><li>Meninges </li></ul><ul><li>Blood supply </li></ul><ul><li>Venous drainage </li></ul><ul><li>CSF </li></ul>
  4. 4. Scalp <ul><li>Skin </li></ul><ul><li>Connective tissue layer </li></ul><ul><li>Aponeurotic layer-frontalis, occipitalis and temporalis merge </li></ul><ul><li>Pericranium </li></ul><ul><li>Blood supply </li></ul><ul><ul><li>ECA and ICA </li></ul></ul><ul><ul><li>Vessels run in dense connective tissue so bleed profusely when cut(can’t retract) </li></ul></ul>
  5. 5. Structure of the brain <ul><li>Forebrain </li></ul><ul><ul><li>Cerebrum </li></ul></ul><ul><ul><ul><li>2 cerebral hemispheres </li></ul></ul></ul><ul><ul><ul><li> connected by corpus callosum </li></ul></ul></ul><ul><ul><ul><li>Cerebral hemispheres have </li></ul></ul></ul><ul><ul><ul><li>central cavities called the lateral </li></ul></ul></ul><ul><ul><ul><li>ventricles </li></ul></ul></ul><ul><ul><ul><li>Gyri and sulci </li></ul></ul></ul><ul><ul><li>Diencephalon </li></ul></ul><ul><ul><ul><li>Thalamus </li></ul></ul></ul><ul><ul><ul><li>Hypothalamus </li></ul></ul></ul><ul><ul><ul><li>Third ventricle (communicates with the lateral ventricles through the interventricular foramina) </li></ul></ul></ul>
  6. 6. Structure of the brain <ul><li>Midbrain </li></ul><ul><ul><li>Cerebral peduncles </li></ul></ul><ul><ul><li>(consists of descending </li></ul></ul><ul><ul><li>tracts from the cerebrum </li></ul></ul><ul><ul><li>to the spinal cord) </li></ul></ul><ul><ul><ul><li>Crus cerebri </li></ul></ul></ul><ul><ul><ul><li>Substantia nigra </li></ul></ul></ul><ul><ul><ul><li>tegmentum </li></ul></ul></ul><ul><ul><li>Tectum </li></ul></ul><ul><ul><ul><li>4 colliculi </li></ul></ul></ul><ul><ul><ul><li>Pineal body </li></ul></ul></ul>
  7. 7. Structure of the brain <ul><li>Hindbrain </li></ul><ul><ul><li>Pons </li></ul></ul><ul><ul><li>Medulla oblongata </li></ul></ul><ul><ul><li>Cerebellum </li></ul></ul>
  8. 9. Meninges <ul><li>Dura mater </li></ul><ul><ul><li>Falx cerebri </li></ul></ul><ul><ul><li>Tentorium cerebelli </li></ul></ul><ul><ul><li>Extradural space- </li></ul></ul><ul><ul><ul><li>seperates dura from the skull </li></ul></ul></ul><ul><ul><ul><li>meningeal vessels run in this </li></ul></ul></ul><ul><ul><ul><li>contains venous sinuses </li></ul></ul></ul><ul><ul><li>Subdural space </li></ul></ul><ul><ul><ul><li>seperates arachnoid from dura </li></ul></ul></ul>
  9. 10. Meninges <ul><li>Arachnoid mater </li></ul><ul><ul><li>Arachnoid villi project into dural sinuses </li></ul></ul><ul><ul><li>Subarachnoid space-contains CSF-is traversed by cranial nerves,arteries and veins </li></ul></ul><ul><li>Pia Mater </li></ul><ul><ul><li>Invests brain and SC tissue </li></ul></ul>
  10. 11. Blood supply
  11. 12. CSF <ul><li>Produced in the choroid plexus of the lateral 3rd and 4th ventricles </li></ul><ul><li>Flow is from the lateral to the 3rd to the 4th ventricle via cerebral aqueduct </li></ul><ul><li>Then flows into sunarachnoid space via 2 foramen of Luschka and the single foramen of magendie </li></ul><ul><li>Absorbed back into the blood stream via the arachnoid villi which project into the sagittal sinus </li></ul><ul><li>140mls contained in adult </li></ul><ul><li>500ml/day produced </li></ul>
  12. 13. Neurophysiology <ul><li>Blood brain barrier </li></ul><ul><ul><li>Selectively controls entry of substances into the ECF of the CNS </li></ul></ul><ul><ul><li>Consists of endothelial cells with tight junctions </li></ul></ul><ul><ul><li>Active mechanisms exist to transport substances </li></ul></ul><ul><ul><li>May be compromised in cases of severely raised intracranial pressure </li></ul></ul>
  13. 14. Intracranial pressure <ul><li>Normal ICP=10mmHg </li></ul><ul><li>Abnormal>20 mmHg </li></ul><ul><li>Monroe Kellie doctrine states </li></ul><ul><ul><li>the cranial compartment is incompressible </li></ul></ul><ul><ul><li>the volume inside the cranium is a fixed volume </li></ul></ul><ul><ul><li>its constituents namely blood, CSF, and brain tissue create a state of volume equilibrium </li></ul></ul><ul><ul><li>any increase in volume of one of the cranial constituents must be compensated by a decrease in volume of another. </li></ul></ul>
  14. 15. Monroe-Kellie doctrine CSF Brain Blood Compensation occurs up to a value of 100mls. eg. an increase in lesion volume (e.g. extradural hematoma) will be compensated by the downward displacement of CSF and venous blood.
  15. 16. Why is ICP important <ul><li>Cerebral perfusion pressure(CPP)= mean arterial pressure(MAP)-ICP </li></ul><ul><li>MAP=1/3 pulse pressure+diastolic blood pressure </li></ul><ul><li>Thus decreasing ICP or increasing MAP leads to an increase in CPP </li></ul><ul><li>CPP is normally controlled by auto regulation with arteriolor vasoconstriction keeping a constant value between 50 and 1500mmHg. </li></ul><ul><li>If this fails as in pathological states this can lead to a significant drop in CPP </li></ul>
  16. 17. Causes of raised ICP <ul><li>-Surgical </li></ul><ul><ul><ul><li>Haematoma </li></ul></ul></ul><ul><ul><ul><li>Oedema due to contusion/haematoma </li></ul></ul></ul><ul><ul><ul><li>Oedema due to ischaemia </li></ul></ul></ul><ul><ul><ul><li>Infection-empyema </li></ul></ul></ul><ul><ul><li>- Medical </li></ul></ul><ul><ul><ul><li>Electrolyte imbalance </li></ul></ul></ul><ul><ul><ul><li>Ischaemia-CVA </li></ul></ul></ul><ul><ul><ul><li>Infection-meningitis </li></ul></ul></ul>
  17. 18. ICP cont’d <ul><li>Effects of raised ICP </li></ul><ul><ul><li>Tentorial herniation </li></ul></ul><ul><ul><li>Pupillary dilatation due to compression of 3rd CN </li></ul></ul><ul><ul><li>Motor weakness due to compression of corticospinal tract </li></ul></ul><ul><ul><li>Coning-brainstem is being squeezed through the foramen magnum compressing cardiorespiratory centres </li></ul></ul>
  18. 19. Raised ICP <ul><li>Symptoms </li></ul><ul><ul><li>Decreased conscious level </li></ul></ul><ul><ul><li>Headache </li></ul></ul><ul><ul><li>Nausea and vomiting </li></ul></ul><ul><li>Signs </li></ul><ul><ul><li>Fall in GCS </li></ul></ul><ul><ul><li>Dilated pupil </li></ul></ul><ul><ul><li>Papilloedema </li></ul></ul>
  19. 20. Neurological assessment in A&E <ul><li>Always commence with </li></ul><ul><ul><li>Airway </li></ul></ul><ul><ul><li>Breathing </li></ul></ul><ul><ul><li>Circulation </li></ul></ul><ul><ul><li>Disability </li></ul></ul><ul><ul><ul><li>Neurological status </li></ul></ul></ul><ul><ul><ul><li>Pupils </li></ul></ul></ul>
  20. 21. Disability <ul><li>Brief assessment </li></ul><ul><li>Pupils </li></ul><ul><ul><li>Size </li></ul></ul><ul><ul><li>Symmetry </li></ul></ul><ul><ul><li>Response to light </li></ul></ul><ul><li>AVPU score </li></ul><ul><ul><li>A lert </li></ul></ul><ul><ul><li>V erbal stimuli </li></ul></ul><ul><ul><li>P ain </li></ul></ul><ul><ul><li>R esponsive </li></ul></ul>
  21. 22. Secondary Survey of the head <ul><li>Neurological state </li></ul><ul><ul><li>GCS </li></ul></ul><ul><ul><li>Pupils </li></ul></ul><ul><ul><li>Eyes </li></ul></ul><ul><li>Examination of the face </li></ul><ul><ul><li>Facial bones </li></ul></ul><ul><ul><li>Teeth </li></ul></ul><ul><li>Examination of the scalp </li></ul>
  22. 23. Secondary survey of the head <ul><li>Examination of the scalp </li></ul><ul><ul><li>Battle’s sign-fracture of the base of the skull </li></ul></ul><ul><ul><li>CSF/blood from ears </li></ul></ul><ul><ul><li>Presence of scalp wound/haematoma </li></ul></ul>
  23. 24. Glasgow coma scale
  24. 25. Classification of head injury <ul><li>GCS </li></ul><ul><ul><li>Minor-GCS>8 </li></ul></ul><ul><ul><li>Major-GCS<8 </li></ul></ul><ul><li>Mechanism </li></ul><ul><ul><li>Blunt </li></ul></ul><ul><ul><li>Penetrating </li></ul></ul><ul><li>Pathology </li></ul><ul><ul><li>Focal/Diffuse </li></ul></ul><ul><ul><li>Primary/Secondary </li></ul></ul>
  25. 26. Intracranial haemorrhage <ul><li>Classification </li></ul><ul><ul><li>Contusion </li></ul></ul><ul><ul><li>Extradural haematoma </li></ul></ul><ul><ul><li>Subdural haematoma </li></ul></ul><ul><ul><li>Subarachnoid haemorrhage </li></ul></ul><ul><ul><li>Intracerebral haemorrhage </li></ul></ul><ul><ul><li>Diffuse axonal injury </li></ul></ul>
  26. 27. Contusions <ul><li>Classed under focal brain injury </li></ul><ul><li>Due to rapid deceleration injuries </li></ul><ul><li>The brain hits off the rigid skull causing coup and contre coup bruising </li></ul><ul><li>Coup injury occurs under the site of impact with an object </li></ul><ul><li>Contrecoup injury occurs on the side opposite the area that was impacted </li></ul>
  27. 28. Contusions <ul><li>Frontal and temporal contusions are common </li></ul><ul><li>Also cause mass effect as a result of blood and oedema which leads to midline shift </li></ul>
  28. 29. Extradural haematoma <ul><li>Due to trauma-blow to temporal or parietal bone </li></ul><ul><li>Causes rupture of underlying middle meningeal artery </li></ul><ul><li>Presents as initial concussion followed by lucid interval due to accommodation of expanding haematoma. </li></ul>
  29. 30. Extradural haematoma <ul><li>Followed by rapid decompensation as ICP raises when the temporal lobe is pushed into the tentorial opening. </li></ul><ul><li>This is called coning. </li></ul><ul><li>Carries a 5% to 20% mortality rate. </li></ul>
  30. 31. Extradural haematoma Respects the suture lines. Seen on CT Brain as lens- shaped blood collection with a convex medial border .
  31. 32. Acute Subdural haematoma <ul><li>Severe head injury-Sudden deceleration injuries --leads to a more rapid deterioration in patient’s condition. </li></ul><ul><li>Due to </li></ul><ul><ul><li>rupture of a bridging vein due to shearing forces </li></ul></ul><ul><ul><li>laceration of brain substance </li></ul></ul><ul><li>Thin layer of blood in the subdural space (between the dura and arachnoid mater) </li></ul>
  32. 33. Acute Subdural haematoma Appear on Ct Brain as crescent-shaped blood collections with a concave medial border. This does not resect the suture lines. Note also midline shift.
  33. 34. Subarachnoid haemorrhage <ul><li>Trauma is the most common cause of Subarachnoid haemorrhage </li></ul><ul><li>Bleeding occurs between the arachnoid and pia mater.. SAH may be complicated by hydrocephalus. </li></ul><ul><li>Confusion can sometimes arise between SAH due to trauma and due to a ruptured aneurysm or arteriovenous malformation (AVM); the patient may collapse and hit their head as a result of a bleed and the history (from the patient or a witness) is important. </li></ul>
  34. 35. Subarachnoid haemorrhage <ul><li>Increased attenuation </li></ul><ul><li>is seen in the CSF spaces </li></ul><ul><li>over the cerebral </li></ul><ul><li>hemispheres </li></ul><ul><li>(look closely at </li></ul><ul><li>the Sylvian fissure), </li></ul><ul><li>in the basal cisterns or </li></ul><ul><li>in the ventricular system. </li></ul><ul><li>It may be complicated </li></ul><ul><li>further by Hydrocephalus </li></ul>
  35. 36. Intracerebral haematoma <ul><li>Injury of the brain substance itself </li></ul><ul><li>Associated with cerebral laceration, contusion, oedema and necrosis </li></ul><ul><li>Evacuation of the clots can have poor results </li></ul><ul><li>Not as easy to remedy. </li></ul>
  36. 37. Diffuse axonal injury <ul><li>Occurs due to shearing forces between grey and white matter. </li></ul><ul><li>Generalized cerebral oedema results due to parenchymal disruption leadsing to an increase in ICP </li></ul><ul><li>Ranges from </li></ul><ul><ul><li>mild form-concussion </li></ul></ul><ul><ul><li>severe form- persistent vegetative state </li></ul></ul>
  37. 38. Monitoring of ICP <ul><li>Invasive </li></ul><ul><ul><li>External ventricular drain(EVD)- inserted via frontal Burr hole into lateral ventricles. This allows drainage of CSF if necessary </li></ul></ul><ul><ul><li>Brain parenchymal ICP transducer- catheter is introduced through Burr hole and placed in contact with parenchyma and linked to pressure transducer </li></ul></ul><ul><li>Non- invasive </li></ul><ul><ul><li>Transcranial pressure-estimates flow in middle meningeal artery. </li></ul></ul>
  38. 39. Medical management of raised ICP <ul><li>Sedate and intubate </li></ul><ul><li>Nurse patient at 30 degree angle-aids venous drainage </li></ul><ul><li>Mild hyperventilation- keep pCO2 approx 4.5kPa- if allowed to fall lower this leads to vasoconstriction and subsequent ischaemia </li></ul><ul><li>Mild hypothermia </li></ul>
  39. 40. Medical management of raised ICP <ul><li>Maintain ICP at 10 mmHg </li></ul><ul><ul><li>Mannitol(0.5g/kg)- transient mild reduction in ICP </li></ul></ul><ul><ul><li>Hyperventilation </li></ul></ul><ul><ul><li>Hypothermia </li></ul></ul><ul><ul><li>Thiopentone infusion(5mg/kg) </li></ul></ul><ul><li>Aim to maintain CPP at 60-70mmHg </li></ul><ul><ul><li>Fluid management </li></ul></ul><ul><ul><li>Use of inotropes(this increases MAP) </li></ul></ul>
  40. 41. Surgical management <ul><li>External ventricular drainage-drain CSF to transiently reduce ICP </li></ul><ul><li>Burr holes </li></ul><ul><li>Evacuation of mass lesion +/- craniectomy </li></ul><ul><li>Decompressive craniectomy </li></ul>
  41. 42. Surgical management <ul><li>Burr Holes </li></ul><ul><ul><li>Small holes through the skull over the site of an intracranial haematoma </li></ul></ul><ul><ul><li>Aim is for partial evacuation and reduction in ICP </li></ul></ul><ul><ul><li>Must be placed directly over haematoma </li></ul></ul><ul><ul><li>Temporary measure only whilst awaiting definitive neurosurgical intervention </li></ul></ul><ul><ul><li>Also used for insertion of invasive monitoring equipment </li></ul></ul>
  42. 43. Surgical management <ul><li>Decompressive craniectomy </li></ul><ul><ul><li>part of the skull is removed to allow the brain room to expand </li></ul></ul><ul><ul><li>some evidence suggests that it does improve outcome by lowering ICP </li></ul></ul><ul><ul><li>The part of the skull that is removed is known as a bone flap </li></ul></ul>

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