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Brain herniation imaging
This document discusses different types of brain herniation seen on imaging. The most common types are subfalcine herniation and descending transtentorial herniation. Subfalcine herniation occurs when one hemisphere pushes across the midline under the falx cerebri. Descending transtentorial herniation occurs when the temporal lobe and hippocampus herniate through the tentorial incisura. Other types discussed include tonsillar herniation, ascending transtentorial herniation, and rare transdural herniations. Complications of herniations include hydrocephalus, nerve compression, and infarcts.
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Brain herniation imaging
- 1. BRAIN HERNIATION SYNDROMEA Pictorial Review Thorsang Chayovan R1/Aj.Nuttha 22.11.2014
- 4. BRAIN HERNIATION •most common types –Subfalcine herniation –descending transtentorial herniation •Others –Posterior fossa herniations •ascending transtentorial herniation •tonsillar herniation –Transalar herniation •Rare but important types –transdural/transcranial herniations –brain displacements across the sphenoid wing
- 5.
- 6. Subfalcine herniation •mostcommon •supratentorial mass in one hemicranium •affected hemisphere pushes across the midline under the inferior "free" margin of the falx, extending into the contralateral hemicranium
- 9. Subfalcine herniation: imaging Axial and coronal images show that •cingulate gyrus •anterior cerebral artery (ACA) •internal cerebral vein (ICV) are pushed from one side to the other under the falx cerebri. The ipsilateral ventricle appears compressed and displaced across the midline
- 11. Complications •unilateral obstructivehydrocephalus –foramen of Monro occlusion •Periventricular hypodensity with "blurred" margins of the lateral ventricle –Fluid accumulates in the periventricular white matter
- 12. Complications •When severe,the herniating ACA can be pinned against the inferior "free" margin of the falx cerebri secondary infarction of the cingulate gyrus
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- 15. Transtentorial herniations descendingherniations ascending herniations
- 16. Descending transtentorial herniations •the second most common •a hemispheric mass •initially produces subfalcine herniation •As the mass effect increases, the uncus of the temporal lobe is pushed medially begins to encroach on the suprasellar cistern hippocampus follows hippocampus effaces the ipsilateral quadrigeminal cistern both the uncus and hippocampus herniate inferiorly through the tentorial incisura
- 17. "Dysautonomia, Multisystem Atrophyand Parkinson's." Dysautonomia, Multisystem Atrophy and Parkinson's. N.p., n.d. Web. 18 Nov. 2014
- 19. Descending transtentorial herniation •Unilateral •Bilateral ("central“) –Severe
- 20. unilateral DTH: imaging early uncus is displaced medially Ipsilateral aspect of the suprasellar cistern effaced Ipsilateral prepontine + cerebellopontine angle cistern enlarged
- 22. Descending transtentorial herniation As DTH increases hippocampus also herniates medially quadrigeminal cistern compression midbrain pushed toward the opposite side of the incisura
- 23. Descending transtentorial herniation severe cases entire suprasellar and quadrigeminal cisterns are effaced. The temporal horn can even be displaced almost into the midline
- 25. bilateral DTH bothhemispheres become swollen the whole central brain is flattened against the skull base All the basal cisterns are obliterated hypothalamus and optic chiasm are crushed against the sella turcica
- 28. Complete bilateral DTH both temporal lobes herniate medially into the tentorial hiatus midbrain and pons displaced inferiorly through the tentorial incisura The angle between the midbrain and pons is progressively reduced from 90° to almost 0°
- 30. Complications •CN III(oculomotor) nerve compression –CN III palsy •PCA occlusion as it passes back up over the medial edge of the tentorium –secondary PCA (occipital) infarct
- 33. Kernohan notch •Asthe herniating temporal lobe pushes the midbrain toward the opposite side of the incisura –contralateral cerebral peduncle is forced against the hard edge of the tentorium •Pressure ischemia ipsilateral hemiplegia –the "false localizing" sign
- 37. Duret hemorrhage "Top-down"mass effect displaces the midbrain inferiorly closes the midbrain-pontine angle Perforating arteries from basilar artery are compressed and buckled secondary hemorrhagic midbrain infarct
- 38. Brainstem hemorrhage Brainstemhemorrhage Dorsolateral Primary injury Severe DAI Ventral paramedian Duret
- 39. Hemorrhage in diffuseaxonal injury •Gray-white junction •Corpus callosum •Brainstem
- 40. hypothalamic and basalganglia infarcts complete bilateral DTH perforating arteries from the circle of Willis compression against the central skull base hypothalamic and basal ganglia infarcts
- 44. POSTERIOR FOSSA MASS:TONSILLAR HERNIATION ASCENDING TRANSTENTORIAL HERNIATION
- 46. Tonsillar herniation •Thecerebellar tonsils are displaced inferiorly and become impacted into the foramen magnum. •congenital (e.g., Chiari 1 malformation) – mismatch between size and content of the posterior fossa •Acquired –an expanding posterior fossa mass pushing the tonsils downward—more common –intracranial hypotension: abnormally low intraspinal CSF pressure •tonsils are pulled downward
- 47. Tonsillar herniation: imaging •Diagnosing tonsillar herniation on NECT scans may be problematic. Cisterna magna obliteration
- 49. Tonsillar herniation: imaging •MR: much more easily diagnosed •In the sagittal plane –the tonsillar folia become vertically oriented –the inferior aspect of the tonsils becomes pointed –Tonsils > 5 mm (or 7 mm in children) below the foramen magnum are generally abnormal •especially if they are peg-like or pointed (rather than rounded)
- 50. Tonsillar herniation: imaging •In the axial plane, T2 scans show that the tonsils are impacted into the foramen magnum –obliterating CSF in the cisterna magna –displacing the medulla anteriorly
- 52. Complications •obstructive hydrocephalus •tonsillar necrosis
- 53.
- 55. Ascending transtentorial herniation •caused by any expanding posterior fossa mass –Neoplasms > trauma
- 58. Complications •Acute intraventricularobstructive hydrocephalus –caused by compression of the cerebral aqueduct
- 61. OTHER LESS COMMONHERNIATION: TRANSALAR TRANSDURAL/TRANSCRANIAL HERNIATIONS
- 62. Transalar Herniation •brainherniates across the greater sphenoid wing (GSW) or "ala" •ascending > descending
- 63. Ascending transalar herniation •caused by a large middle cranial fossa mass •An intratemporal or large extraaxial mass Temporal lobe + sylvian fissure + MCA up and over the greater sphenoid wing
- 67. Descending transalar herniation •caused by a large anterior cranial fossa mass Gyrus rectus is forced posteroinferiorly over the GSW displacing the sylvian fissure and shifting the MCA backward
- 68. Transdural/Transcranial Herniation •Rare •Sometimes called a "brain fungus" •can be life-threatening Lacerated dura + a skull defect + increased ICP
- 70. Transdural/Transcranial Herniation •Traumatic –infants or young children with a comminuted inward skull fracture •Iatrogenic –a burr hole, craniotomy, or craniectomy
- 71. Transdural/Transcranial Herniation •MRbest depicts these unusual herniations. •The disrupted dura –discontinuous black line on T2WI –Brain tissue, blood vessels, and CSF, are extruded through the defects into the subgaleal space
- 74. Kaewlai, R. Imagingof Traumatic Brain Injury. 2013.
- 75.
- 80. References •Osborn, AnneG. "Secondary Effects and Sequellae of CNS Trauma."Osborn's Brain: Imaging, Pathology, and Anatomy. Salt Lake City, UT: Amirsys Pub., 2013. N. pag. Print. •Osborn, Anne G. "Cerebral Vasculature: Normal Anatomy and Pathology."Diagnostic Neuroradiology. St. Louis: Mosby, 1994. N. pag. Print. •Kaewlai, R. Imaging of Traumatic Brain Injury. 2013. Web.