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Full story brain herniation imaging Dr Ahmed Esawy

Full story brain herniation imaging Dr Ahmed Esawy
include different cases for oral radiodiagnosis examination all over the world
CT /MRI Plain X ray images
I Supratentorial herniation
1-Cingulate (subfalcine/transfalcine)
2-Uncal (descending transtentorial herniation DTH)
3-Central (bilateral DTH)
4-Transcalvarial
5-Tectal (posterior)

II-Infratentorial herniation
1-Upward
(upward cerebellar or upward transtentorial)
2-Tonsillar (downward cerebellar
III-Sphenoid/alar herniation Transalar Herniation

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Full story brain herniation imaging Dr Ahmed Esawy

  1. 1. IMAGING BRAIN HERNIATION Dr. Ahmed Esawy MBBS M.Sc. MD Dr Ahmed Esawy
  2. 2. CLASSIFICATION BRAIN HERNAITION I Supratentorial herniation 1-Cingulate (subfalcine/transfalcine) 2-Uncal (descending transtentorial herniation DTH) 3-Central (bilateral DTH) 4-Transcalvarial 5-Tectal (posterior) II-Infratentorial herniation 1-Upward (upward cerebellar or upward transtentorial) 2-Tonsillar (downward cerebellar III-Sphenoid/alar herniation Transalar Herniation Dr Ahmed Esawy
  3. 3. Brain herniation A brain herniation is when brain tissue, cerebrospinal fluid, and blood vessels are moved or pressed away from their usual position inside the skull. Causes Brain herniation occurs when something inside the skull produces pressure that moves brain tissues. This is most often the result of brain swelling from a •head injury, stroke •or brain tumor. Brain herniation can be a side effect of tumors in the brain, including: Metastatic brain tumor Primary brain tumour (brain tumours,meningioma,base of skull tumours, suprasellar tumours Herniation of the brain can also be caused by other factors that lead to increased pressure inside the skull, including: •Abscess •Hemorrhage (intracerebral ,subdural ,extradual) •Hydrocephalus •Strokes that cause brain swelling •Swelling after radiation therapy Dr Ahmed Esawy
  4. 4. Pathology of Increased Intracranial Pressure  Increased intracranial pressure (ICP): - if > 40 mm Hg  cerebral hypoxia, cerebral ischemia, cerebral edema, hydrocephalus, and brain herniation.  Cerebral edema: Edema - Disruption of the blood brain barrier – vasodilatation – swelling.  Hydrocephalus  communicating type common inTotal Body Irradiation. Dr Ahmed Esawy
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  7. 7. Cingulate herniation (subfalcine/transfalcine) Dr Ahmed Esawy
  8. 8. Cingulate herniation (subfalcine/transfalcine) Subfalcine herniation on CT In cingulate or subfalcine herniation, the most common type, the innermost part of the frontal lobe is scraped under part of the falx cerebri, the dura mater at the top of the head between the two hemispheres of the brain Cingulate herniation can be caused when one hemisphere swells and pushes the cingulate gyrus by the falx cerebri cingulate herniation may present with abnormal posturing and coma Dr Ahmed Esawy
  9. 9. the cingulate gyrus lies on the medial aspect of the cerebral hemisphere. It forms a major part of the limbic system which has functions in emotion and behaviour.The frontal portion is termed the anterior cingulate gyrus (or cortex) Dr Ahmed Esawy
  10. 10. Subfalcine herniation most common •supratentorial mass in one hemicranium •affected hemisphere pushes across the midline under the inferior "free" margin of the falx, extending into the contralateral hemicranium 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 Dr Ahmed Esawy
  11. 11. Subfalcine herniation Complications • unilateral obstructive hydrocephalus –foramen of Monro occlusion •Periventricular hypodensity with "blurred" margins of the lateral ventricle –Fluid accumulates in the periventricular white matter •When severe, the herniating ACA can be pinned against the inferior "free" margin of the falx cerebri • secondary infarction of the cingulate gyrus Dr Ahmed Esawy
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  13. 13. Subfalcine herniation from acute SDH Dr Ahmed Esawy
  14. 14. acute on chronic subdural hematoma. Subfalcine herniation, midline shift, effacement of the ipsilateral lateral ventricle, and enlargement of the contralateral occipital horn are present. Dr Ahmed Esawy
  15. 15. Coronal contrast-enhancedTi-weighted image of patient with metastatic breast cancer. Coronal MR imaging accurately shows ipsilateral cingulate gyrus (asterisk) displaced beneath falx with depression of corpus callosum.There is compression of contralateral cingulate gyrus (straight arrow) and corpus callosum. Pencailosal artery (curved arrow) is displaced beneath falx. Lateral and third ventricles are also displaced. subfaicine herniation. Dr Ahmed Esawy
  16. 16. Degrees of subfalcine herniation. A, Axial CT scan of right parietal posttraumatic hemorrhage and subdural hematoma (arrowheads). some compression of right lateral ventricle is present, with shift to left asso- ciated with mild deviation of anterior faix (arrow). B, Axial CT scan of massive right infarct. Right lateral ventricle is compressed and markedly displaced to opposite side. Note that posterior falx remains non displaced despite massive shift including anterior faix (arrow) Dr Ahmed Esawy
  17. 17. Paradoxical herniation The postoperative CT image shows evidence of left craniectomy with a small amount of residual subdural fluid collection and blood. A repeat CT image upon returning after 4 months shows resolution of the subdural fluid collection and blood after 4 months there is interval demonstration of concave deformity of the left cerebral hemisphere together with the overlying skin flap, with associated distortion of the left ventricle and a new left subfalcine paradoxical herniationDr Ahmed Esawy
  18. 18. the tentorium is a structure within the skull formed by the dura mater of the meninges Transtentorial herniation can occur when the brain moves either up or down across the tentorium, called ascending and descending transtentorial herniation respectively; however descending herniation is much more common Dr Ahmed Esawy
  19. 19. Uncal herniation (Descending transtentorial herniations ) Dr Ahmed Esawy
  20. 20. Descending transtentorial herniation types •Unilateral •Bilateral ("central“) Severe Dr Ahmed Esawy
  21. 21. Uncal herniation (Descending transtentorial herniations ) In uncal herniation, a common subtype of transtentorial herniation, the innermost part of the temporal lobe, the uncus, can be squeezed so much that it moves towards the tentorium and puts pressure on the brainstem, most notably the midbrain Dr Ahmed Esawy
  22. 22. The uncus is an anterior extremity of the Parahippocampal gyrus. It is separated from the apex of the temporal lobe by a slight fissure called the incisura temporalis. Dr Ahmed Esawy
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  25. 25. Parietal lobe Superior temporal gyrus Middle temporal gyrus Pons Medulla oblongata Cerebral peduncle Centrum semiovale 3rd ventricle Inferior temporal gyrus Petrous ridge of temporal bone Parahippocampal gyrus Dr Ahmed Esawy
  26. 26. Pontine cistern pre-pontine cistern • Anterior to the pons.Location • Basilar A. • AICA. • Ant. Pontomesencephalic V. • Cn 5. • Cn 6. Contents Dr Ahmed Esawy
  27. 27. Pontine cistern Dr Ahmed Esawy
  28. 28. Pontine cistern Basilar A Ant. PontomesencephalicV PetrosalV Superior petrosal sinus Dr Ahmed Esawy
  29. 29. Pontine cistern Dr Ahmed Esawy
  30. 30. Pontine cistern AICA BA Cn6 Cn6 BA Dr Ahmed Esawy
  31. 31. Perimesencephalic cistern 1. Interpeduncular C. 2. Crural C. 3. Ambient C. 4. Quadrigeminal C. Dr Ahmed Esawy
  32. 32. Quadrigeminal cistern vein of Galen cistern • Posterior to the quadrigeminal plate, • Inferior to the splenium of corpus callosum & • Superior to the cerebellum Location • Vein of Galen . • PrecentralV. • P3 of PCA. Contents Dr Ahmed Esawy
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  34. 34. Chiasmatic cistern Suprasellar cistern • Above the sella.Location • Optic chiasm. • Pituitary infundibulum Contents Dr Ahmed Esawy
  35. 35. CP angle cistern AICA Dr Ahmed Esawy
  36. 36. Superior CP angle cistern AICA AICA AICA AICA Dr Ahmed Esawy
  37. 37. Inferior CP angle cistern Cn 9/10 Cn 10 Cn 9 Dr Ahmed Esawy
  38. 38. Uncal herniation (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 Dr Ahmed Esawy
  39. 39. Uncal herniation (Descending transtentorial herniations ) The uncus can squeeze the oculomotor nerve (a.k.a.CN III), which may affect the parasympathetic input to the eye on the side of the affected nerve Compression of the ipsilateral posterior cerebral artery Duret hemorrhages (tearing of small vessels in the parenchyma) in the median and paramedian zones of the mesencephalon and pons The sliding uncus syndrome represents uncal herniation without alteration in the level of consciousness and other sequelae mentioned above. Dr Ahmed Esawy
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  41. 41. Descending transtentorial herniation As DTH increases hippocampus also herniates medially quadrigeminal cistern compression midbrain pushed toward the opposite side of the incisura Descending transtentorial herniation severe cases entire suprasellar and quadrigeminal cisterns are effaced. The temporal horn can even be displaced almost into the midline Dr Ahmed Esawy
  42. 42. Brain herniation. 1, subfalcine; 2, herniation of the uncus and hippocampal gyrus of the temporal lobe into the tentorial notch, causing pressure on the third nerve and mid-brain; 3, brainstem caudally; 4, cerebellar tonsils through foramen magnum. Dr Ahmed Esawy
  43. 43. Uncal herniation is when the medial portion of the anterior temporal lobe is shifted into the suprasellar cistern. It is a subset of descending transtenorial herniation, which is when the cerebral hemisphere crosses the tentorium at the level of the incisura. It can result in Infarct in the PCA distribution Dr Ahmed Esawy
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  46. 46. A large right frontotemporal subdural hematoma is exerting mass effect on the right frontal and temporal lobes, with resultant effacement of the suprasellar cistern and with right-sided uncal herniation. effaces the ipsilateral temporal horn, causing dilatation of the contralateral temporal horn. Subfalcine herniation and narrowing of the contralateral ambient and quadrigeminal plate cisterns are present. Dr Ahmed Esawy
  47. 47. Acute-on-chronic right temporal subdural hematoma exerts mass effect on the right temporal lobe, causing ipsilateral temporal horn, with effacement and dilatation of the contralateral temporal horn. Narrowing of the contralateral ambient and quadrigeminal plate cisterns is present, with ipsilateral widening of the ambient and quadrigeminal cisterns. Dr Ahmed Esawy
  48. 48. Duret hemorrhage with cerebral herniation. Large left holohemispheric and parafalcine subdural hematoma (short black arrows, a) results in midline shift (long black arrow, a) and uncal (long white arrow, b) herniation. Downward brainstem herniation has led to classic Duret hemorrhage (short white arrow, b) in the paramedian midbrain Dr Ahmed Esawy
  49. 49. descending transtentorial herniation. A-C, Axial diagram (A ), axial CT scan (B), and axialT2- weighted MR image (C) show components of left unilateral descending transtentorial herniation (straight arrows). Brainstem is rotated and displaced to opposite side and caudally, producing widening of ipsilateral ambient cistern (curved arrows). Compression of neck of contralateral temporal horn results in its dilatation (asterisk Dr Ahmed Esawy
  50. 50. Descending transtentonal herniation. A and B, Coronal diagram (A) and coronalTi- weighted MR Image (B) show components of left unilateral descending transtentorial herniation (curved arrows). MR image shows extent of herniation across tentorium and deviation of brainstem. Dr Ahmed Esawy
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  52. 52. bilateral DTH both hemispheres 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 Dr Ahmed Esawy
  53. 53. Central herniation(bilateral DTH) In central herniation, the diencephalon and parts of the temporal lobes of both of the cerebral hemispheres are squeezed through a notch in the tentorium cerebelli. Radiographically, downward herniation is characterized by obliteration of the suprasellar cistern from temporal lobe herniation into the tentorial hiatus with associated compression on the cerebral peduncles. Upwards herniation, on the other hand, can be radiographically characterized by obliteration of the quadrigeminal cistern. Intracranial hypotension syndrome has been known to mimic downwards transtentorial herniation. Dr Ahmed Esawy
  54. 54. 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° Dr Ahmed Esawy
  55. 55. Complete bilateral DTH 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 Duret hemorrhage diabetes insipidus due to the compression of the pituitary stalk Dr Ahmed Esawy
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  57. 57. BILateral descending transtentorlal herniation. Axial CT scan reveals bilateral descending transtentorial herniation with obliteration of perimesencephalic cisterns. Dorsal midbrain is compressed and dongated anteroposteriorly, causing pear-shaped deformity (asterisk) Dr Ahmed Esawy
  58. 58. Nine-year-old boy with diffuse cerebral edema and central herniation secondary to treatment of DKA Juvenile Diabetic Ketoacidosis . A, Axial noncontrast CT scan shows diffuse cerebral edema with effacement of sulci and basal cisterns. B, Axial noncontrast CT scan obtained 2 days after A shows marked low-density infarcts in the gyrus recti and medial orbital gyri (arrows), globus pallidi, hippocampi/parahippocampal gyri, hypothalamus, midbrain, and posterior right temporal lobe. Dr Ahmed Esawy
  59. 59. C–D, Axial noncontrastT2-weighted (4000/105/1) (C) and coronal postcontrastT1-weighted SPGR (14.4/3.7/1) (D) MR images obtained 24 days after A show cavitary infarcts in the gyrus recti and medial orbital gyri (arrows), medial temporal lobes, midbrain and thalami. Enhancement is present within the thalamic and midbrain lesions.There is diffuse cerebral atrophy. Dr Ahmed Esawy
  60. 60. Kernohan notch •Kernohan notch phenomenon is an imaging finding resulting from extensive midline shift due to mass effect, resulting in indentation in the contralateral cerebral crus by the tentorium cerebelli.This has also been referred to as Kernohan-Woltman notch phenomenon and false localising sign. As the 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 Dr Ahmed Esawy
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  63. 63. subfalcine and downward transtentorial Kernohan phenomenon Dr Ahmed Esawy
  64. 64. flair T1 T1+C subfalcine and downward transtentorial Kernohan phenomenon Dr Ahmed Esawy
  65. 65. T1+C FLAIR T2 T2 ASTROCYTOMA GII DOWNWARD TRANTENTORAIL HERNIATION Dr Ahmed Esawy
  66. 66. Uncal herniation with Kernohan phenomenon Dr Ahmed Esawy
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  72. 72. complications of transtentorial herniation. Midbrain (Duret’s) hemorrhage. Axial CT scan of patient with head trauma reveals left transtentorial herniation with deformity of brainstem. Midline hemorrhage is seen within upper pons (arrow) caused by herniation Dr Ahmed Esawy
  73. 73. Infratentorial herniation DESCENDINGTONSILLAR HERNIATION ASCENDINGTRANSTENTORIAL HERNIATION Dr Ahmed Esawy
  74. 74. Tentorial incisure(also known as the tentorial notch or incisura tentorii) to the anterior opening between the free edge of the tentorium cerebelli and theclivus for the passage of the brainstem. It's located between the tentorial edges and communicates the supratentorial and infratentorial spaces Tentorial incisure seen from above The propensity of tonsillar herniation to follow descending tentorial herniation is related to the size and shape of the incisura. If the incisura is small, the patient will be less likely to have tonsillar herniation Dr Ahmed Esawy
  75. 75. DownwardTonsillar herniation In tonsillar herniation, also called downward cerebellar herniation] transforaminal herniation, or "coning", the cerebellar tonsils move downward through the foramen magnum possibly causing compression of the lower brainstem and upper cervical spinal cord Tonsillar herniation of the cerebellum is also known as a Chiari malformation (CM), Cerebellar tonsillar ectopia (CTE) is a term used by radiologists to describe cerebellar tonsils that are "low lying" Dr Ahmed Esawy
  76. 76. DescendingTonsillar herniation •The cerebellar 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 (tumour, haemorrhage,stroke, abscess) pushing the tonsils downward—more common –intracranial hypotension: abnormally low intraspinal CSF pressure tonsils are pulled downward Diagnosing tonsillar herniation on NECT scans may be problematic. Cisterna magna obliteration Dr Ahmed Esawy
  77. 77. life threatening tonsillar herniation exerting mass effect on the brain parenchyma can displace the posterior cranial fossa structures inferiorly. In doing so the brainstem is compressed against the clivus thereby altering the vital life- sustaining functions of the pons and medulla, such as the respiratory and cardiac centres. Non-life threatening tonsillar descent can bee seen in conditions such as Chiari malformations Dr Ahmed Esawy
  78. 78. SagittalT1-weighted magnetic resonance image of the brain. Anatomic landmarks identified include the fourth ventricle (A), basion (B), medulla oblongata (C), cerebellar tonsil (D), opisthion (E), cerebellar hemisphere (F). Dr Ahmed Esawy
  79. 79. he distance is measured by drawing a line from the inner margins foramen magnum (basion to opisthion), and measuring the inferior most part of the tonsils As is to be expected, values used vary somewhat from author to author above foramen magnum: normal <5 mm: also normal but the term benign tonsillar ectopia can be used >5 mm: Chiari 1 malformation Dr Ahmed Esawy
  80. 80. -A, Drawing showing basion (B), opisthion (0), and cerebellar tonsil (T) in a normal patient. B, Midline sagittal section, SE 500/40, showing line from basion to opisthion in a nomal patient. Measurements were from this Dr Ahmed Esawy
  81. 81. reference line. Bottoms of tonsils have a normal, rounded appearance and CSF is seen in a normal cisterna magna. Dr Ahmed Esawy
  82. 82. Coronal SE 700/40 through medulla and tonsils.The lower limits of foramen magnum are difficult to identify. Coronal scans were not used for this reason. Dr Ahmed Esawy
  83. 83. DescendingTonsillar herniation 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) 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 Complications •obstructive hydrocephalus •tonsillar necrosis Dr Ahmed Esawy
  84. 84. Dr Ahmed Esawy
  85. 85. Normal anatomy of the cerebellum (left). Chiari I malformation (right). With the size of the posterior fossa too small, the cerebellar tonsils may herniate through the skull into the spinal canal.The tonsils block the flow of CSF (blue) and may cause fluid buildup inside the spinal cord, called a syrinx. Dr Ahmed Esawy
  86. 86. A, Midline sagittal SE 500/40 scan in a symptomatic patient.Tonsils extend 1.1 cm below foramen magnum.Tonsils are "pointed" and cisterna magna is obliterated.The latter two findings were seen in both asymptomatic symptomatic patients with low tonsils. B, Midline sagittal SE 500/40 scan after decompression via suboccipital craniectomy. Tonsils now have a normal rounded appearance. Dr Ahmed Esawy
  87. 87. Typical MRI manifestation of brain sagging.MidsagittalT1-weighted MRI shows downward displacement of the cerebellar tonsil by 5 mm (arrow). brain sagging, which was defined as either cerebral aqueduct displacement ≥1.8 mm or cerebellar tonsil displacement ≥4.3 mm subdural haematoma in patients with spontaneous intracranial hypotension. Dr Ahmed Esawy
  88. 88. Typical MRI manifestation of the venous distension sign.T1-weighted MRI through the midportion of the dominant transverse sinus shows the venous distension sign (box) subdural haematoma in patients with spontaneous intracranial hypotension. Dr Ahmed Esawy
  89. 89. An MRI of the brain shows the cerebellar tonsils (arrow) herniating through the foramen magnum (yellow line). Dr Ahmed Esawy
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  92. 92. With a loss in CSF volume, there is a greater increase in blood volume.This results in dural venous hyperemia and pachymeningeal venous engorgement and edema, which can be identified on MR imaging as diffuse pachymeningeal enhancement. Furthermore, the decrease in volume of the suspending CSF results in downward descent of the brain and can cause descending central transtentorial herniation and tonsillar herniation. A blood patch or surgical repair of the dural defect is usually required. Dr Ahmed Esawy
  93. 93. Intracranial hypotension. (A) Coronal enhancedT1-weighted MR image demonstrates diffuse pachymeningeal enhancement (arrows) in a patient with severe postural headaches. (B) Sagittal enhancedT1-weighted NM image reveals tonsillar herniation (arrow), descending transtentorial herniation (note downward descent of the brainstem, loss of surrounding CSF spaces and flattening of the pons against the clivus) and pachymeningeal enhancement (arrowheads). (C) Postmyelogram CT scan of the thoracic spine shows an extradural accumulation of contrast (arrow) within die spinal canal consistent with a CSF leak.The extradural and intradural confluent medium outlines the dura (arrowhead) at the T10 level. A blood patch performed at this level resulted in resolution of the patient's symptoms. Dr Ahmed Esawy
  94. 94. Tonsillar herniation. Sagittal enhancedT I -weighted MR image demonstrates a large enhancing cerebellar mass causing both tonsillar herniation and ascending transtentorial herniation. Note the inferior displacement of the tonsils (arrow) below the foramen magnum and the effacement of the surrounding CSF spaces.The brainstem is compressed and displaced against the clivus and there is upward displacement of the superior cerebellar vermis (arrowhead) through the incisura.Dr Ahmed Esawy
  95. 95. Dr Ahmed Esawy
  96. 96. Foramen magnum/tonsillar herniation child with a history of an Arnold-Chiari I malformation. Image shows tonsillar herniation with compression of the central canal at the craniocervical junction and resultant syringohydromyelia in the visualized portion of the cervical spinal cord. T2-. through the cervical spine was obtained in the same patient as in the previous image.The cerebellar tonsils are projecting inferiorly below the level of the opisthion, with compression of the central canal at the craniocervical junction. Hyperintense syringohydromyelia in the visualized portion of the cervical spinal cord is demonstrated.Dr Ahmed Esawy
  97. 97. tonsiliar herniation and ascending transtentorial herniation. A, SagittalTi -weighted MR image of patient with cerebellar astrocytoma. Cerebeliar tonsils are displaced through foramen magnum, compressing medulla and upper cervical cord. Note that there is also ascending transtentorial herniation with tentorium bowed superiorly (curved arrow). B,Axial contrast- enhancedTi-weighted MR image shows cerebeliar tonsils (asterisks) displaced into foramen magnum Dr Ahmed Esawy
  98. 98. ASCENDINGTRANSTENTORIAL HERNIATION Dr Ahmed Esawy
  99. 99. Upward herniation Increased pressure in the posterior fossa can cause the cerebellum to move up through the tentorial opening in upward, or cerebellar herniation.The midbrain is pushed through the tentorial notch Dr Ahmed Esawy
  100. 100. Ascending transtentorial herniation caused by any expanding posterior fossa mass Neoplasms > trauma Dr Ahmed Esawy
  101. 101. MR and CT findings of ascending transtentorial herniation include Effacement of the superior cerebellar cistern superior displacement of the superior vermis through the incisura compression of the midbrain forward displacement of the pons against the clivus . can compress the posterior cerebral artery or superior cerebellar arteries against the tentorium, resulting in infarctions can compress the aqueduct of Sylvius, resulting in hydrocephalus. Obstruction of venous outflow by compression of the vein of Galen and basal vein of Rosenthal may occur and further increase intracranial pressure. Dr Ahmed Esawy
  102. 102. (5) ascending transtentorial Dr Ahmed Esawy
  103. 103. Ascending transtentorial herniation. (A) AxialT I - weighted MR image and (B) sagittal enhancedT I -weighted MR image demonstrate ascending transtentorial herniation in a patient with a cerebellar lung metastases. Note the upward displacement of the superior cerebellar vermis (black arrows) through the incisura, compression of the fourth ventricle, and anterior displacement of the pons (arrowhead) against the clivus. Dr Ahmed Esawy
  104. 104. Ascending transtentorial herniation Right parasagittal gadolinium-enhancedT1-weighted magnetic resonance image in a 9-year-old girl with a history of right cerebellar astrocytoma who presented with headaches and vomiting. Heterogeneously enhancing mass is demonstrated in the right cerebellum, with compression of the adjacent brainstem and fourth ventricle. Ascending transtentorial herniation of the cerebellum is demonstrated through the incisura. Descending tonsillar herniation also is present. Axial gadolinium-enhancedT1-weighted magnetic resonance image obtained at the level of the midbrain in the same patient as in the previous image. A heterogeneously enhancing mass is seen in the right medial anterior cerebellum, with mass effect on the right posterior lateral midbrain and fourth ventricle.The image shows enlargement of the temporal horns of both lateral ventricles as a result of obstruction by the cerebellar mass at the level of the fourth ventricle. Dr Ahmed Esawy
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  107. 107. upward herniation from cerebellar infarction /oedema Dr Ahmed Esawy
  108. 108. ascending transtentorial herniation. Axial CT scan obtained after posterior fossa surgery with subsequent cerebellar hemorrhage and edema. Perimesencephalic cistern is effaced. Trapped temporal horns are caused by aqueductal compression and hydrocephalus Dr Ahmed Esawy
  109. 109. unilateral ascending transtentorial herniation. A, Axial CT scan of patient with right cere- bellar astrocytoma shows distortion of right quadrlgeminal cistern (arrow) and brainstem compression caused by upward herniation. B, AxialTi-weighted MR image shows leftsided cerebellar cystic medulloblastoma with marked compression and rotation of midbrain. Frequently, midbrain is elevated and pons, following midbrain, is forced against clivus Dr Ahmed Esawy
  110. 110. Sphenoid/alar herniation Transalar Herniation brain herniates across the greater sphenoid wing (GSW) or "ala" ascending > descending Dr Ahmed Esawy
  111. 111. descending transalar herniation Descending transphenoidal herniation occurs when anterior cranial fossa mass effect causes displacement of the posterior frontal lobe over the sphenoid wing into the middle cranial fossa. Ascending transalar herniation Ascending transphenoidal herniation is produced by middle cranial fossa mass effect, which causes displacement of the anterior temporal lobe over the sphenoid ridge into the anterior cranial fossa. Dr Ahmed Esawy
  112. 112. transalar herniation Temporal lobe + sylvian fissure + MCA up and over the greater sphenoid wing The middle cerebral artery can become compressed between the displaced brain and the sphenoid ridge, resulting in middle cerebral artery infarction Although vascular compromise may occur with transphenoidal herniation, it is rare. Moreover, the clinical features of this type of herniation are poorly defined. Dr Ahmed Esawy
  113. 113. ascending transalar herniation. Axial contrast-enhanced CT scan of patient with right temporal lobe gliobiastoma shows contrast filled right middle cerebral artery (arrow) displaced anteriorly.Also present is asymmetry and effacement of ipsilateral sylvian fissure.These changes indicate ascending transalar herniation. Dr Ahmed Esawy
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  117. 117. Transphenoidal herniation. Sagittal enhanced Tl- weighted MR image demonstrates a large ring enhancing mass (arrowhead) in the right frontal lobe causing descending transphenoidal herniation (arrow) Dr Ahmed Esawy
  118. 118. Descending transalar herniation. A, Coronal enhancedTi-weighted MR image shows left frontal lobe glioblastoma.When compared with normal right side, medial orbital gyrus of left frontal lobe Is displaced over sphenold ridge into middle cranial fossa (arrow). B, Sagittal enhancedTi-weighted MR image shows tumor and resultant transalar herniation (arrow). Left syivian fissure is effaced. Compare this image with normal right side. C, Sagittal enhancedTi-weighted MR image shows normal position of right frontal lobe (asterisk) above sylvian fissure (arrow Dr Ahmed Esawy
  119. 119. Extracranial herniation /Transcalvarial /transdural herniation Dr Ahmed Esawy
  120. 120. Dr Ahmed Esawy
  121. 121. Extracranial herniation /Transcalvarial /transdural/Transcranial herniation the brain squeezes through a fracture or a surgical site in the skull. Also called "external herniation •Traumatic –infants or young children with a comminuted inward skull fracture •Iatrogenic –a burr hole, craniotomy, or craniectomy MR best depicts these unusual herniations. •The disrupted dura –discontinuous black line onT2WI –Brain tissue, blood vessels, and CSF, are extruded through the defects into the subgaleal space Dr Ahmed Esawy
  122. 122. Nonenhanced computed tomography (CT) scan of the brain at the level of the body of the lateral ventricles was obtained in a 37-year-old man who underwent a right frontotemporal decompression craniectomy for a large right frontal hematoma after a skiing accident. A focal hypoattenuating infarct is seen in the right frontal lobe, with an adjacent edematous brain parenchyma herniating through the right frontotemporal craniectomy defect.The patient had communicating hydrocephalus with dilatation of the lateral ventricles. Dr Ahmed Esawy
  123. 123. Dr Ahmed Esawy
  124. 124. fungus cerebri. A, Axial CT scan of patient with chronic head injury shows left hemispheric encephalomaiacia and dilated lateral ventricle. Brain tis- sue is identified herniating through calvarlal defect. B, AxialTi-weighted MR image of patient with severe head trauma. Swollen brain is seen herniating through calvarial defect (arrows outline margins of defect ). Hemorrhage is seen adjacent to defect’s anterior rim, which may be result of herniatlon or initial injur Dr Ahmed Esawy
  125. 125. focal herniation Into surgical defect. Coronal contrast- enhancedTi-weighted MR image of patient following radical mastoidectomy for cholesteatoma that extended into epitympanum and mastoid antrum. Postoperatively, there Is dehiscence of tegmen tympani with focal herniatlon of temporal lobe into middle ear cavity (arrow) sur- rounded by enhancing granulation tissue.This finding can easily be misinterpreted as middle ear mass Dr Ahmed Esawy
  126. 126. Dr Ahmed Esawy
  127. 127. Dr Ahmed Esawy
  128. 128. Common CNS Herniations: Dr Ahmed Esawy
  129. 129. Cerebral Herniation: PathogenesisSite of herniation Effect Clinical consequence Transtentorial Ipsilateral 3rd cranial nerve compression Ipsilateral fixed dilated pupil Ipsilateral 6th cranial nerve compression Horizontal diplopia, convergent squint Posterior cerebral artery compression Occipital infarction Cortical blindness Cerebral peduncle compression Upper motor neurone signs Brainstem compression and haemorrhage Decerebrate posture Cardiorespiratory failure Death Foramen magnum Brainstem compression and haemorrhage Decerebrate posture Cardiorespiratory failure Death Acute obstruction of CSF pathway Decerebrate posture Cardiorespiratory failure DeathDr Ahmed Esawy
  130. 130. THANKYOU Dr Ahmed Esawy
  131. 131. Pathogenesis:  Supratentorial herniation common. 3 sub types  Subfalcine herniation:The cingulate gyrus of the frontal lobe (commonest) :The brain can shift across falx cerebri  Central transtentorial herniation: displacement of the basal nuclei and cerebral hemispheres downward  Uncal herniation: Medial edge of the uncus and the hippocampal gyrus  infratentorial herniation : Cerebellar (tonsillar) herniation: - tonsil of the cerebellum is pushed through the foramen magnum and compresses the medulla, leading to bradycardia and respiratory arrest. Dr Ahmed Esawy
  132. 132. Subfalcine Herniation: in brain trauma.Contusion of the inferior temporal lobe (blue arrow) has resulted in diffuse edema. (compressed and flattened gyri on the right). This has resulted in subfalcine herniation of the cingulate gyrus (red arrow), with a secondary hemorrhagic infarction above that (black arrow). A midline shift from right to left is also present, as is uncal herniation (yellow arrow). Dr Ahmed Esawy
  133. 133. Uncal Herniation: Inferior view,The herniated uncus is bulging over the position of the tentorium (black arrows) and compressing the midbrain.The two mammillary bodies (blue arrows) have been shifted to the patients right due to the pressure. Dr Ahmed Esawy
  134. 134. Uncal Herniation: Dr Ahmed Esawy
  135. 135. acute brain swelling + Uncal Herniation Swelling of the left cerebral hemisphere has produced a shift with herniation of the uncus of the hippocampus through the tentorium, leading to the groove seen at the white arrow. Dr Ahmed Esawy
  136. 136. Cerebellar Tonsil - Herniation Note the cone shape of the herniated tonsils around the medulla in this cerebellum specimen.  Results in compression and Duret hemorrhages in the pons. Dr Ahmed Esawy
  137. 137. Transtentorial herniation:  Transtentorial herniation at the base of the brain. A prominent groove surrounds the displaced parahippocampal gyrus (arrow).The adjacent 3rd nerve (N) is compressed and distorted and the ipsilateral cerebral peduncle (P) is distorted with small areas of haemorrhage. Dr Ahmed Esawy

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