Transcript Brain edema
بسم هللا الرحمن الرحيم BRAIN CT IN EMERGENCY Lecture Objectives: • • • • • • • Normal anatomy of brain CT Trumatic brain injury Subarachnoid hemorrhage Intraparenchymal hemorrhage Stroke Brain edema Cerebral herniation A. Orbit B. Sphenoid Sinus C. Temporal Lobe D.Externa Auditory Canal E. Mastoid Air Cells F. Cerebellar Hemisphere A. Anterior Horn of the Lateral Ventricle B. Caudate Nucleus C. Anterior Limb of the Internal Capsule D. Putamen and Globus Pallidus E. Posterior Limb of the Internal Capsule F. Third Ventricle G. Quadrigeminal Plate Cistern H. Cerebellar Vermis I. Occipital Lobe A. Falx Cerebri B. Frontal Lobe C. Body of the Lateral Ventricle D. Splenium of the Corpus Callosum E. Parietal Lobe F. Occipital Lobe G. Superior Sagittal Sinus A. Falx Cerebri B. Sulcus C. Gyrus D. Superior Sagittal Sinus CT SCAN.. Bone window fracture CT SCAN.. Contrast enhanced CT: IV injection of contrast medium is often given because the abnormality not seen in pre contrast scans may be rendered visible following contrast enhancement (consequence of breakdown of blood brain barrier allowing contrast to enter the lesion particularly in neoplasm, infection, inflammation and certain stage of ischemia). Also it is helpful in demonstrating blood vessels MCA ACA Basilar artery Straight sinus Superior sagittal sinus Contrast enhanced CT CT SCAN.. Computer reconstructions can in selected circumstances be made from the axial sections which then provide images in coronal or sagittal planes. Sagittal reconstruction Coronal reconstruction CT SCAN.. CTA CT angiography is helpful in diagnosis of vascular diseases and abnormalities such as stenosis, occlusion or vascular malformation Occlusion of left middle cerebral artery Computed Tomographic Cerebral Venography (CTV) CTV Can be reliably assess intracranial venous system Comparable to MR angiographic techniques Rapid and readily available Avoids many patient contraindications that may prevent MR evaluation Using iodinated contrast material, requires complex post processing to remove bony structures from reconstructed images CT SCAN.. CT PERFUSION cerebral blood volume cerebral blood flow CT SCAN.. CT PERFUSION In acute stroke, very early cranial CT may be normal. Perfusion CT shows great promise in refining the selection of patients suitable for thrombolysis, as it can accurately determine infarct core from potentially salvageable ischaemic penumbra. Some cerebral tumours are associated with angiogenesis and a breakdown of the blood-brain barrier. Angiogenesis can be detected as an increase in flow and volume parameters, and blood-brain barrier breakdown can be quantified as contrast accumulates in the interstitial space. Such aggressive features can distinguish malignant from benign tumours when standard imaging may not. Traumatic brain injury: • Primary: • Extraaxial hemorrhage: - Epidural hematoma - Subdural hematoma - Subarachnoid hemorrhage • Intraaxial lesions: - Diffuse axonal injury - Cortical contusion - Deep gray matter injury - Brainstem injury - IVH • Secondary: - Brain herniation - Traumatic ischemia - Diffuse cerebral edema - Hypoxic brain injury Epidural hematoma • 90% is arterial (middle meningeal artery) • Temporoparietal • Biconvex, lenticular • Does not cross suture lines, crosses dural reflections • Commonly associated with skull fractures CT SCAN.. Bone window Brain window fracture Acute extradural hemorrhage The window settings are selected for the brain, but may be altered to shows the bones. Subdural hematoma • Tear of cortical bridging veins • Cresentric along the brain surface • Crosses suture lines, does not cross dural reflections • Common in infants (child abuse) and in the elderly Subarachnoid hemorrhage • Hyperdense CSF in the basal cisterns, sylvian fissure and subarachnoid space • Aneurysm rupture is the most common cause in non trauma patient • Patients present with the worst headache of their life Subarachnoid hemorrhage Subarachnoid hemorrhage • The pattern of hemorrhage may give a clue to the location of the ruptured aneurysm: • A-com aneurysm ⇒ interhemispheric fissure • P-com aneurysm ⇒ ipsilateral basal cisterns • MCA trifurcation ⇒ sylvian fissure • Basilar tip ⇒ interpeduncular cistern, intraventricular • PICA ⇒ posterior fossa cisterns, intraventricular Pseudo-subarachnoid hemorrhage • Symmetric increased density in the basal cisterns with no sulcal density • 30-40 HU • Assoaciated with generalized brain edema • History of recent cardiopulmonary resuscitation Diffuse axonal injury • Axonal disruption from shearing forces of acceleration/deceleration • Patients are unconscious with severe head injury • Common locations: - Lobar gray/white matter junction - Corpus callosum - Dorsolateral brain stem Diffuse axonal injury • Initial CT is often normal. Petechial hemorrhage develops later. • Susceptibility-sensitive, gradient-echo MR sequences are most sensitive for detecting hemorrhagic shear injuries. Diffuse axonal injury Cortical contusions • Focal hemorrhage/edema secondary to brain impacting on bone or dura • Located 180 degrees from the site of direct impact (contrecoup) • Characteristic locations: - Anterior temporal - Inferior frontal - Parasagittal hemisphere - Splenium of the corpus callosum - Brainstem Intra ventricular hemorrhage Intraparenchymal hemorrhage • Causes: - Hypertension - Amyloid angiopathy - Vascular malformations - Coagulopathy - Trauma - Drug induced - Tumor hemorrhage Stroke • Types: - Ischemic stroke - Hemorrhagic stroke - Venous occlusion Ischemic stroke • Nonenhanced CT is the initial investigation of choice • Exclude hemorrhage and underlying mass or AVM Imaging findings: • • • • • Normal in early stroke Hyperdense clot in the affected artery Insular ribbon sign Sulcal effacement Cytotoxic edema develops by 6 hours Ischemic stroke • Acute infarction cannot be excluded on the basis of a negative CT. • Diffusion weighted MRI is most sensitive for detecting acute infarction • Hemorrhagic transformation can develop in the subacute stage (gradient echo MRI) Insular Ribbon Sign 1st Day 2nd Day Old CT Recent CT PICA Infarction Dense basilar artery (arrow). Compare this to the normal internal carotid artery (arrowhead). Cerebral Venous Thrombosis • Can involve the: dural sinuses, cortical veins or deep cerebral veins Venous occlusion Spectrum of CT findings • 10-30% of cases of CVT are negative on either unenhanced or contrast-enhanced CT • Highly suspicious cases should be furtherly evaluated with CT venography or MRI • Unenhanced CT: Direct signs of CVT “dense clot sign” seen only on 30% of cases. Diffuse brain edema 20-50% • Unenhanced CT: Venous infarction: • Not conforming to a major arterial vascular territory, • Involving subcortical region • solitary or multiple isolated lesions • Hemorrhagic or non hemorrhagic. • Unenhanced CT: Bilateral infarction at thalami, basal ganglia and internal capsules suggesting deep venous thrombosis • Contrast-Enenhanced CT: Direct evidence of CVT “Empty Delta Sign” Indirect evidence of CVT may be seen as contrast enhancement of the adjacent dura or vascular engorgement CT Venography: Allow direct visualization of thrombus as filling defect 1st day 2nd day Diagnostic Pitfalls Pseudodelta sign Normal variant of dense sinus Unenhanced CT scans show subdural hemorrhage along falx and tentorium cerebelli, simulating sagittal and transverse sinus thrombosis. Brain edema • Cytotoxic: - Due to cellular swelling - In the setting of cerebral ischemia - Involves both gray and white matter • Vasogenic: - Disruption of BBB and leakage of fluid outside capillaries - Associated with tumors and abscesses - Involves only the white matter Brain edema Cytotoxic Vasogenic Diffuse brain edema • Causes include: ischemia and severe head injury • High morbidity and mortality • Effacement of the cortical sulci and basal cisterns • Loss of gray/white matter interface • White cerebellum sign Cerebral herniation • Mechanical displacement of the brain secondary to mass effect • Causes neurologic dysfunction and vascular compromise • Types: - Subfalcine - Transtentorial (descending, ascending) - Tonsillar Cerebral herniation • Subfalcine herniation: - The cingulate gyrus slips under the falx cerebri - Compression of the ipsilateral ventricle and enlargement of the contralateral ventricle - ACA ischemia Cerebral herniation • Descending transtentorial herniation (uncal): - The medial temporal lobe displaces through the tentorial notch - Presents clinically with deteriorating level of consciousness, ipsilateral 3rd nerve palsy and contralateral motor deficit - Effacement of the ipsilateral suprasellar cistern and enlargement of the ipsilateral CPA cistern - The midbrain impacts the contralateral tentorium (Kernohan’s phenomenon, Duret hemorrhage) - PCA ischemia Cerebral herniation