traumatic brain injury

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Traumatic brain injury Lecture

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  • Traumatic Brain Injury

    Epidural hematoma Subdural hematomaAcute contusion and laceration

  • Material to read later-Layers of the Meninges

  • Traumatic Vascular InjuryVascular injury is a frequent component of CNS trauma and results from direct trauma and disruption of the vessel wall, leading to hemorrhageHemorrhage will occur in any of several compartments (sometimes in combination): epidural, subdural, subarachnoid, and intraparenchymal

  • EPIDURAL HEMATOMAEpidural Hematoma: in which rupture of meningeal artery, usually associated with a skull fracture, leads to accumulation of arterial blood between the dura and the skull. This blood clot can cause fast changes in the pressure inside the brain. Emergency surgery may be needed. The size of the clot will determine if surgery is needed.

  • Traumatic Vascular InjuryEpidural HematomaVessels that course within the dura, most importantly the middle meningeal artery, are vulnerable to injury, particularly with skull fracturesThe expanding hematoma has a smooth inner contour that compresses the brain surfaceClinically, patients can be lucid for several hours between the moment of trauma and the development of neurologic signsEDH is considered to be the most serious complication of head injury, requiring immediate diagnosis and surgical intervention (mortality rate associated with epidural hematoma has been estimated to be 5-50%

  • PathophysiologyUsually results from a brief linear contact force to the calvaria that causes separation of the periosteal dura from bone and disruption of interposed vessels due to shearing stress Skull fractures occur in 85-95% of adult cases Extension of the hematoma usually is limited by suture lines owing to the tight attachment of the dura at these locations.The temporoparietal region and the middle meningeal artery are involved most commonly (66%)

  • FrequencyEpidural hematoma complicates 2% of cases of head trauma (approximately 40,000 cases per year)Alcohol and other forms of intoxication have been associated with a higher incidence of epidural hematomaSexmore frequent in men, with a male-to-female ratio of 4:1Age rare in individuals younger than 2 yearsrare in individuals older than 60 years because the dura is tightly adherent to the calvaria

  • HistoryHead traumaLucid interval between the initial loss of consciousness at the time of impact and a delayed decline in mental status (10-33% of cases)HeadacheNausea/vomitingSeizuresFocal neurological deficits (eg, visual field cuts, aphasia, weakness, numbness)

  • Diagnostic ImagingNoncontrast CT scanning of the head (imaging study of choice for intracranial EDH) not only visualizes skull fractures, but also directly images an epidural hematomaIt appears as a hyperdense biconvex or lenticular-shaped mass situated between the brain and the skull, though regions of hypodensity may be seen with serum or fresh blood. Adjacent skull fracture, cerebral edema, midline deviation MRI also demonstrates the evolution of an epidural hematoma, though this imaging modality may not be appropriate for patients in unstable condition

  • Diagnostic ImagingCT of the head obtained without intravenous contrast enhancement shows a biconvex high-attenuation epidural hematoma adjacent to the right frontal lobe (arrows). The lesion extends superiorly to the level of the body of the lateral ventricle (arrow)

  • SUBDURAL HEMATOMAIn a subdural hematoma (right), damage to bridging veins between the brain and the superior sagittal sinus leads to the accumulation of blood between the dura and the arachnoid. If this bleeding occurs quickly it is called an acute subdural hematoma. If it occurs slowly over several weeks, it is called a chronic subdural hematoma. The clot may cause increased pressure and may need to be removed surgically.

  • Subdural HematomaRapidly clotting blood collection below the inner layer of the dura but external to the brain and arachnoid membraneTypically, low-pressure venous bleeding of bridging veins (between the cortex and venous sinuses) dissects the arachnoid away from the dura and layers out along the cerebral convexityIt conforms to the shape of the brain and the cranial vault, exhibiting concave inner margins and convex outer margins (crescent shape)Frequency is related directly to the incidence of blunt head trauma Its the most common type of intracranial mass lesion, occurring in about a third of those with severe head injuries

  • ACUTE AND SUBACUTE SUBDURAL HEMATOMA

    ACUTE

    Associated with major head injury involving contussion and lacerations

    SUBACUTE

    Are the result of less severe contussions and head trauma.

  • CHRONIC SUBDURAL HEMATOMACan develop seemingly minor head injury.Commonly in elderly.Resembles other conditions.May be mistaken as strokes.Bleeding is less profuse.Compressions of the intracranial contents.

  • Mortality/AgeMortalitySimple SDH (no parenchymal injury) is associated with a mortality rate of about 20%Complicated SDH (parenchymal injury) is associated with a mortality rate of about 50% AgeIts associated with age factors related to the risk of blunt head traumaMore common in people older than 60 years (bridging veins are more easily damaged/falls are more common)Bilateral SDHs are more common in infants since adhesions existing in the subdural space are absent at birthInterhemispheric SDHs are often associate with child abuse

  • HistoryUsually involves moderately severe to severe blunt head trauma Subdural hematomas most often become manifest within the first 48 hours after injuryAcute deceleration injury from a fall or motor vehicle accident, but rarely associated with skull fractureGenerally loss of consciousnessAny degree or type of coagulopathy should heighten suspicion of SDHCommonly seen in alcoholics because theyre prone to thrombocytopenia, prolonged bleeding times, and blunt head traumaPatients on anticoagulants can develop SDH with minimal trauma and warrant a lowered threshold for obtaining a head CT scan

  • Diagnostic ImagingMRI is superior for demonstrating the size of an acute SDH and its effect on the brain, however noncontrast head CT is the primary means of making a diagnosis and suffice for immediate management purposesNoncontrast head CT scan (imaging study of choice for acute SDH) The SDH appears as a hyperdense (white) crescentic mass along the inner table of the skull, most commonly over the cerebral convexity in the parietal region. The second most common area is above the tentorium cerebelliContrast-enhanced CT or MRI is widely recommended for imaging 48-72 hours after head injury because the lesion becomes isodense in the subacute phaseIn the chronic phase, the lesion becomes hypodense and is easy to appreciate on a noncontrast head CT scan

  • Diagnostic ImagingAxial CT images of the brain show a large isodense right-sided subdural hematoma (short arrows) extending from the high convexities to the low frontal lobe. It is producing extensive right to left midline shift with subfalcine (arrow)

  • SummaryEpidural HematomaPotential space between the dura in the inner table of the skullCant cross suturesSkull fractures in temporoparietal regionMiddle meningeal arteryLenticular or biconvex shapeLucid intervalCommon in alcoholicsMedical emergencyCT without contrastEvacuate via burr holesSubdural HematomaBetween the dura mater and the arachnoid materCan cross suturesCortical bridging veinsCrescent shapeLoss of consciousnessCommon in elderlyCommon in alcoholicsMedical emergencyCT without contrastEvacuate via burr holes

  • Epidural hematoma (left) in which rupture of meningeal artery, usually associated with a skull fracture, leads to accumulation of arterial blood between the dura and the skull. In a subdural hematoma (right), damage to bridging veins between the brain and the superior sagittal sinus leads to the accumulation of blood between the dura and the arachnoid.Summary

  • CONTUSSIONCerebral contusion, latin contusio cerebri, a form of traumatic brain injury, is a bruise of the brain tissue. Like bruises in other tissues, cerebral contusion can be caused by multiple microhemorrhages, small blood vessel leaks into brain tissue. Head CT scans of unconscious patients reveal that 20% have hemorrhagic contusion.Damage occurs at (and sometimes opposite) the point of impactthe contact part of the gyri with the skull

    Parenchymal Injuries

  • CONTUSSIONAcute cerebral contusion, there are low-density edema with flake high-density shadow(Asterisk), accompanied with subarachnoid hemorrhage in the suprasellar pool, sylvian cistern and around the right falx cerebri(black arrow). The gas in the suprasellar pool indicates basal skull fractures(black arrowhead).

  • CEREBRAL LACERATIONS

    Cerebral lacerations, related to contusions, occur when the piamater or arachnoid membranes are cut or torn.

  • Acute contusion and laceration of brain

    Pathology: regional cerebral edema, necrosis, liquefying, bleeding fociClinical symptoms: headache, nausea, vomiting, disturbance of consciousness

  • Parenchymal Injuries: Concussion

    Concussion is a clinical syndrome of alteration of consciousness secondary to head injury typically brought about by a change in the momentum of the head (movement of the head arrested by a rigid surface)There is instantaneous onset of transient neurologic dysfunction, including loss of consciousness, temporary respiratory arrest, and loss of reflexesAlthough neurologic recovery is complete, amnesia for the event persists

  • DIFFUSE AXONAL INJURY (DAI)Diffuse axonal injury (DAI) is one of the most common and devastating types of traumatic brain injury, meaning that damage occurs over

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