eMedicine Specialties > Radiology > Brain/Spine

Brain, Herniation

Margaret Loh, MD, Staff Physician, Department of Radiology, Santa Clara Valley Medical Center
Mahesh R Patel, MD, Chief, MRI, Department of Diagnostic Imaging, Santa Clara Valley Medial Center

Updated: Mar 16, 2010

Introduction

Background

The brain is an organ of immense complexity and importance to life. In the cranium, dural reflections and bony landmarks divide the brain into anatomic regions. Brain herniation represents mechanical displacement of normal brain relative to another anatomic region secondary to mass effect from traumatic, neoplastic, ischemic, or infectious etiologies. See the images below.

Nonenhanced head computed tomography (CT) scan at the level of the lateral ventricles was obtained in a 78-year-old man who presented with respiratory failure. The image demonstrates a large right frontal and temporal subdural fluid collection with hyperattenuating and hypoattenuating components consistent with an acute on chronic subdural hematoma. Subfalcine herniation, midline shift, effacement of the ipsilateral lateral ventricle, and enlargement of the contralateral occipital horn are present.

Nonenhanced head computed tomography scan at the level of the suprasellar cistern in the same patient as in the above image. 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. Mass effect from the subdural hematoma 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.

Nonenhanced head computed tomography (CT) scan obtained at the level of the inferior pons in the same patient as in the above 2 images. 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.

Herniations of the brain are divided into 5 major categories, as follows:

• Transtentorial herniation
• Subfalcine/cingulate herniation
• Foramen magnum/tonsillar herniation (seen in patients with Arnold-Chiari malformation, as demonstrated in the images below)
  • 
    

    

    T1-weighted sagittal magnetic resonance image through the cervical spine in a 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-weighted sagittal magnetic resonance image through the cervical spine was obtained in the same patient as in the above 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.

    
    
• Sphenoid/alar herniation
• Extracranial herniation

Each category of herniation is associated with a specific neurologic syndrome.
 

Recent studies

Probst et al sought to determine if some patients with brain herniation or significant brain shift diagnosed by cranial CT might still have a normal neurologic examination. Using cranial CT scan radiology reports, CT scans were classified into 3 categories: frank herniation, significant shift without frank herniation, and minimal or no shift. Of the 161 patients who had CT-diagnosed frank herniation, 3 patients (1.9%) had no neurologic deficit. Of 91 patients with significant brain shift but no herniation, 4 (4.4%) were found to have no neurologic deficit.^{[1 ]}

Danzer et al attempted to determine whether reversal of hindbrain herniation (HH) after fetal myelomeningocele (fMMC) closure reduced the incidence and severity of HH-associated brainstem dysfunction (BSD). Median age at follow-up was 72 months (range, 46-98 mo), and 50% of patients required shunting. The majority of fMMC children developed no BSD or only mild BSD at follow-up. HH-related symptoms were completely absent in 15 of 24 (63%) nonshunted patients and 10 of 24 (42%) shunted patients. There were no HH-related deaths, and none of the patients developed severe persistent cyanotic apnea. Neurogenic dysphagia was reported in 2 (8%) nonshunted and 9 (38%) shunted infants. Mild GERD developed in 2 (8%) without and 6 (25%) with shunt placement. Neuro-ophthalmologic disturbances occurred in 6 (25%) nonshunted and 13 (54%) shunted patients.^{[2 ]}

Koenig et al evaluated the use of 23.4% saline (30 to 60 mL) in the management of transtentorial herniation (TTH) in 68 patients (76 TTH events) with supratentorial lesions. In addition, management included hyperventilation (70% of events), mannitol (57%), propofol (62%), pentobarbital (15%), ventriculostomy drainage (27%), and decompressive hemicraniectomy (18%). Reversal of TTH occurred in 57 of 76 events (75%). Intracranial pressure decreased from 23 ± 16 mm Hg at the time of TTH to 14 ± 10 mm Hg at 1 hour and to 11 ± 12 mm Hg at 24 hours in 22 patients. Reversal of TTH was predicted by a rise in serum sodium concentration of 5 mmol/L or more or by an absolute serum sodium of 145 mmol/L or more 1 hour after 23.4% saline. Adverse effects included transient hypotension in 13 events (17%). Twenty-two patients (32%) survived to discharge, with severe disability in 17 and mild to moderate disability in 5.^{[3 ]}

Leikola et al investigated the incidence of Arnold-Chiari malformation in patients with nonsyndromic, single-suture craniosynostosis (N-SSSC). The study involved 124 pediatric patients with N-SSSC who underwent MRI brain scans before craniofacial surgery. Seven of these patients (5.6%)—5 with synostosis of the sagittal suture and 2 with synostosis of the right coronal suture—had an associated, asymptomatic Arnold-Chiari malformation, with the tonsillar herniations having a median size of 9 mm. The authors concluded that there is a relatively common association between Arnold-Chiari malformation and N-SSSC.^{[4 ]}

Pathophysiology

Transtentorial herniation

Transtentorial herniation is a downward or an upward displacement of the brain through the tentorium at the level of the incisura. A descending transtentorial herniation occurs when the supratentorial brain herniates downward through the incisura. Conversely, an ascending transtentorial herniation occurs when the infratentorial brain herniates upward through the incisura.

Descending transtentorial herniation occurs more often than ascending herniations and includes the subcategory of uncal herniation. Mass effect in the cerebrum pushes the supratentorial brain through the incisura; this displacement may lead to a host of neurologic symptoms, as discussed below in Clinical Details.

Ascending transtentorial herniation is usually caused by a posterior fossa tumor with mass effect that pushes the infratentorial brain through the incisura. This results in the distortion of the midbrain, flattening of the posterior quadrigeminal plate, and narrowing of the bilateral ambient cisterns. Extra-axial and intra-axial hematomas of the posterior fossa are less common causes. [see the eMedicine article Posterior Fossa Tumors.]

Subfalcine/cingulate herniation

Subfalcine herniation occurs when the supratentorial brain is displaced underneath the falx secondary to mass effect.

Foramen magnum/tonsillar herniation

Foramen magnum herniation occurs when the infratentorial brain is displaced through the foramen magnum secondary to mass effect.

Sphenoid/alar herniation

Sphenoid/alar herniation results from the supratentorial brain sliding either anteriorly or posteriorly over the wing of the sphenoid bone. An anterior herniation occurs when the temporal lobe herniates anteriorly and superiorly over the sphenoid bone. Conversely, a posterior herniation occurs when the frontal lobe herniates posteriorly and inferiorly over the sphenoid bone.

Extracranial herniation

Extracranial herniation occurs with displacement of brain through a cranial defect.

Frequency

United States

Various causes of brain herniation have been identified; the frequency of occurrence largely depends on the particular etiology.

International

Various causes of brain herniation have been identified; the frequency of occurrence largely depends on the particular etiology.

Mortality/Morbidity

Mortality and morbidity vary with the causes and treatments of brain herniation.

Presentation

Descending transtentorial herniation can cause various symptoms. Compression of ipsilateral cranial nerve III may lead to ipsilateral dilatation of the pupil and abnormal extraocular movements. Compression of the ipsilateral corticospinal tracts in the brainstem may cause contralateral hemiparesis because these tracts decussate at the level of the medulla. Ipsilateral hemiparesis also can occur if there is sufficient mass effect to cause the contralateral cerebral peduncle (Kernohan notch) to be compressed against the adjacent incisura.

Other complications include unilateral or bilateral occipital lobe infarction from compression of the posterior cerebral artery. Brainstem hemorrhages are another complication caused by compression or kinking of pontine perforating vessels. Compression on the midbrain may cause hydrocephalus.

Ascending transtentorial herniation

Ascending transtentorial herniation causing brainstem compression can cause nausea and vomiting, which may progress rapidly to coma if rapid changes occur in the intracranial anatomy. A slow-growing mass in the posterior fossa results in slow changes in the intracranial anatomy; these do not often present as an acute emergency.

Subfalcine/cingulate herniation

Subfalcine herniation does not necessarily indicate severe clinical symptoms. This type of herniation may lead to the clinical findings of headache, and symptoms may progress to contralateral leg weakness or ipsilateral frontal lobe infarction secondary to compression of the anterior cerebral artery.

Foramen magnum/tonsillar herniation

Acute compression of the brainstem may result in obtundation and death. However, patients with an Arnold-Chiari I malformation may present with a paucity of symptoms, or they may present with dysesthesia in the extremities with cervical flexion. This is referred to as Lhermitte phenomenon.^{[4,5 ]}(See the eMedicine article Chiari I Malformation.)

Sphenoid/alar herniation

Associated clinical symptoms are usually minimal, although sphenoid herniations are often associated with other types of herniations.

Extracranial herniation

This finding usually results from a traumatic or surgical cause. The herniated region of the brain may become ischemic, leading to infarction.

Preferred Examination

For transtentorial herniation, computed tomography (CT) scanning or MRI is useful for evaluation. MRI can provide axial, as well as sagittal and coronal, views.

For subfalcine/cingulate herniation, CT scanning or MRI is again useful for evaluation, with MRI able to provide axial, sagittal, and coronal views.

For foramen magnum/tonsillar herniation, MRI provides the best visualization on sagittal and coronal views. However, because patients with this type of herniation often present acutely, axial CT scanning enables visualization of this condition.

For sphenoid/alar herniation, MRI provides the best visualization on parasagittal images. However, axial CT scanning or MRI can demonstrate anterior displacement of the ipsilateral middle cerebral artery, which is an indirect sign of sphenoid herniation.

For extracranial herniation, CT scanning or MRI is useful for evaluation.

Radiography

Findings

Radiography is not useful for the diagnosis of brain herniation.

Computed Tomography

Findings

With a descending transtentorial herniation, mass effect in the cerebrum pushes the supratentorial brain through the incisura.^{[6 ]}

With ascending transtentorial herniation, mass effect from the posterior fossa pushes the infratentorial brain through the incisura (as seen below). This results in the distortion of the midbrain, flattening of the posterior quadrigeminal plate, and narrowing of the bilateral ambient cisterns. Hydrocephalus is frequently noted.

With subfalcine/cingulate herniation (seen below), the supratentorial brain is displaced underneath the anterior falx.

Nonenhanced head computed tomography (CT) scan at the level of the lateral ventricles was obtained in a 78-year-old man who presented with respiratory failure. The image demonstrates a large right frontal and temporal subdural fluid collection with hyperattenuating and hypoattenuating components consistent with an acute on chronic subdural hematoma. Subfalcine herniation, midline shift, effacement of the ipsilateral lateral ventricle, and enlargement of the contralateral occipital horn are present.

Nonenhanced head computed tomography scan at the level of the suprasellar cistern in the same patient as in the above image. 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. Mass effect from the subdural hematoma 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.

Nonenhanced head computed tomography (CT) scan obtained at the level of the inferior pons in the same patient as in the above 2 images. 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.

With sphenoid/alar herniations, the supratentorial brain is sliding anteriorly or posteriorly over the wing of the sphenoid bone. An anterior herniation occurs when the temporal lobe herniates anteriorly and superiorly over the sphenoid bone. Conversely, a posterior herniation occurs when the frontal lobe herniates posteriorly and inferiorly over the sphenoid bone.

With extracranial herniation, the brain is displaced through a cranial defect, as in the image below.

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.

Degree of Confidence

Cross-sectional imaging provides a high degree of confidence.

Magnetic Resonance Imaging

Findings

With descending transtentorial herniation, mass effect in the cerebrum pushes the supratentorial brain through the incisura.

In ascending transtentorial herniation (seen in the images below), mass effect from the posterior fossa pushes the infratentorial brain through the incisura. This results in the distortion of the midbrain, flattening of the posterior quadrigeminal plate, and narrowing of the bilateral ambient cisterns. Hydrocephalus is frequently noted.^{[7 ]}

Right parasagittal gadolinium-enhanced T1-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-enhanced T1-weighted magnetic resonance image obtained at the level of the midbrain in the same patient as in the above 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.

In foramen magnum/tonsillar herniation, the infratentorial brain is displaced through the foramen magnum, as demonstrated below.

T1-weighted sagittal magnetic resonance image through the cervical spine in a 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-weighted sagittal magnetic resonance image through the cervical spine was obtained in the same patient as in the above 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.

Extracranial herniation causes the brain to be displaced through a cranial defect.

Gadolinium-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK], gadoteridol [ProHance]) have recently been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the eMedicine topic Nephrogenic Systemic Fibrosis.

The disease has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or magnetic resonance angiography (MRA) scans. As of late December 2006, the Food and Drug Administration had received reports of 90 such cases. Worldwide, over 200 cases have been reported, according to the FDA. NSF/NFD is a debilitating and sometimes fatal disease. Characteristics include red or dark patches on the skin; burning, itching, swelling, hardening, and tightening of the skin; yellow spots on the whites of the eyes;joint stiffness with trouble moving or straightening the arms, hands, legs, or feet; pain deep in the hip bones or ribs; and muscle weakness. For more information, see the FDA Public Health Advisory or Medscape.

Degree of Confidence

Cross-sectional imaging provides a high degree of confidence.

Ultrasonography

Findings

Neonatal intracranial ultrasonography may have a limited role.

Angiography

Findings

Vascular displacement from mass effect associated with herniation can be seen on cerebral angiograms. Specifically, deep venous anatomic distortion aids in identifying these entities, although CT scanning and MRI are the currently favored diagnostic modalities.

Degree of Confidence

The degree of confidence is high when classic displacement of the deep venous structures is seen.

Intervention

The following treatments are used to decrease intracranial pressure, which can prevent or decrease brain herniation: hyperventilation, mannitol therapy, steroid treatment, barbiturate coma, hypothermia, and surgical intervention. In patients with obstructing hydrocephalus, ventriculostomy is appropriate for relieving some symptoms

Hyperventilation

The presence of carbon dioxide in the intracranial vasculature causes vasodilation. Hyperventilation of an intubated patient to normocapnia (PaCO₂ of 4.0 kPa/30 mm Hg) is the goal for controlling the intracranial pressure. The use of hyperventilation is controversial and has not been shown to improve patient outcomes. Consequently, hyperventilation is reserved for short-term use to gain immediate control when necessary of the intracranial pressure.^{[8 ]}

Drug therapy

Mannitol is an osmotic diuretic.^{[9,10 ]}When given as a bolus, it causes an osmotic gradient, drawing water from neuronal cells. After prolonged use, its osmotic effect decreases because the mannitol molecule itself eventually crosses into the cerebral interstitium, decreasing the beneficial gradient.

Steroid treatment has been known to decrease cerebral swelling by decreasing the cell metabolism in the brain, allowing for healing.^{[11 ]}Dexamethasone 12-20 mg/d is given intravenously or orally, depending on the patient's condition.

The mechanism of action of barbiturates reflects their ability to depress metabolic function; by decreasing cerebral blood flow, they bring about a reduction of intracranial pressure. As the induction of a barbiturate coma may result in systemic hypotension, it should not be routinely administered to patients in unstable condition.

Hypothermia

Hypothermia has been shown to decrease the rate of cerebral metabolism, decreasing cerebral blood flow and intracranial pressure. Hypothermia can reduce the cerebral metabolism rate of oxygen by 5% per degree reduction in core body temperature. Use of this technique is limited, as it increases risk of infection, cardiac arrhythmia, and coagulopathy.

Surgery

Surgical intervention for increased intracranial pressure is dependent on cause. Neoplasms causing brain herniation may be resected or partially resected, if possible, to reduce mass effect. Patients with a large parenchymal and extra-axial hemorrhage may benefit from a standard craniotomy or craniectomy with duraplasty, followed by clot evacuation.^{[12 ]}

In cases of descending transtentorial herniation of the brain caused by a large subdural hematoma, emergency surgical decompression is required to prevent irreversible and catastrophic injury to the brainstem, as well as to other areas of the brain.

Multimedia

Media file 1: Nonenhanced head computed tomography (CT) scan at the level of the lateral ventricles was obtained in a 78-year-old man who presented with respiratory failure. The image demonstrates a large right frontal and temporal subdural fluid collection with hyperattenuating and hypoattenuating components consistent with an acute on chronic subdural hematoma. Subfalcine herniation, midline shift, effacement of the ipsilateral lateral ventricle, and enlargement of the contralateral occipital horn are present.

Media file 2: Nonenhanced head computed tomography scan at the level of the suprasellar cistern in the same patient as in the above image. 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. Mass effect from the subdural hematoma 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.

Media file 3: Nonenhanced head computed tomography (CT) scan obtained at the level of the inferior pons in the same patient as in the above 2 images. 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.

Media file 4: Right parasagittal gadolinium-enhanced T1-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.

Media file 5: Axial gadolinium-enhanced T1-weighted magnetic resonance image obtained at the level of the midbrain in the same patient as in the above 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.

Media file 6: 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.

Media file 7: T1-weighted sagittal magnetic resonance image through the cervical spine in a 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.

Media file 8: T2-weighted sagittal magnetic resonance image through the cervical spine was obtained in the same patient as in the above 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.

References

1. Probst MA, Baraff LJ, Hoffman JR, Wolfson AB, Ourian AJ, Mower WR. Can patients with brain herniation on cranial computed tomography have a normal neurologic exam?. Acad Emerg Med. Feb 2009;16(2):145-50. [Medline].

2. Danzer E, Finkel RS, Rintoul NE, Bebbington MW, Schwartz ES, Zarnow DM, et al. Reversal of hindbrain herniation after maternal-fetal surgery for myelomeningocele subsequently impacts on brain stem function. Neuropediatrics. Dec 2008;39(6):359-62. [Medline].

3. Koenig MA, Bryan M, Lewin JL 3rd, Mirski MA, Geocadin RG, Stevens RD. Reversal of transtentorial herniation with hypertonic saline. Neurology. Mar 25 2008;70(13):1023-9. [Medline].

4. Leikola J, Koljonen V, Valanne L, Hukki J. The incidence of Chiari malformation in nonsyndromic, single suture craniosynostosis. Childs Nerv Syst. Dec 16 2009;[Medline].

5. Aquilina K, Merchant TE, Boop FA, Sanford RA. Chiari I malformation after cranial radiation therapy in childhood: a dynamic process associated with changes in clival growth. Childs Nerv Syst. Nov 2009;25(11):1429-36. [Medline].

6. Yuh EL, Gean AD, Manley GT, Callen AL, Wintermark M. Computer-aided assessment of head computed tomography (CT) studies in patients with suspected traumatic brain injury. J Neurotrauma. Oct 2008;25(10):1163-72. [Medline].

7. Jang SH, Kim DS, Son SM, et al. Clinical application of diffusion tensor tractography for elucidation of the causes of motor weakness in patients with traumatic brain injury. NeuroRehabilitation. 2009;24(3):273-8. [Medline].

8. Muizelaar JP, Marmarou A, Ward JD, et al. Adverse effects of prolonged hyperventilation in patients with severe head injury: a randomized clinical trial. J Neurosurg. Nov 1991;75(5):731-9. [Medline].

9. Kaufmann AM, Cardoso ER. Aggravation of vasogenic cerebral edema by multiple-dose mannitol. J Neurosurg. Oct 1992;77(4):584-9. [Medline].

10. Mendelow AD, Teasdale GM, Russell T, et al. Effect of mannitol on cerebral blood flow and cerebral perfusion pressure in human head injury. J Neurosurg. Jul 1985;63(1):43-8. [Medline].

11. Gutin PH. Corticosteroid therapy in patients with brain tumors. Natl Cancer Inst Monogr. Dec 1977;46:151-6. [Medline].

12. Manawadu D, Quateen A, Findlay JM. Hemicraniectomy for massive middle cerebral artery infarction: a review. Can J Neurol Sci. Nov 2008;35(5):544-50. [Medline].

13. Brant WE, Helms CA. Fundamentals of Diagnostic Radiology. 2^nd ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 1999:61-2.

14. Kan P, Amini A, Hansen K, et al. Outcomes after decompressive craniectomy for severe traumatic brain injury in children. J Neurosurg. Nov 2006;105(5 Suppl):337-42. [Medline].

15. Meadows J, Kraut M, Guarnieri M, et al. Asymptomatic Chiari type I malformations identified on magnetic resonance imaging. J Neurosurg. Jun 2000;92(6):920-6. [Medline].

16. Osborn AG. Diagnostic Neuroradiology. St Louis, Mo: Mosby-Year Book; 1994:222-9, 456.

17. Procaccio F, Stocchetti N, Citerio G, et al. Guidelines for the treatment of adults with severe head trauma (part I). Initial assessment; evaluation and pre-hospital treatment; current criteria for hospital admission; systemic and cerebral monitoring. J Neurosurg Sci. Mar 2000;44(1):1-10. [Medline].

18. Schedler P, Geary S. Kernohan's notch phenomenon: a case study. J Neurosci Nurs. Jun 2002;34(3):158-9. [Medline].

19. Takeuchi K, Yokoyama T, Ito J, et al. Tonsillar herniation and the cervical spine: a morphometric study of 172 patients. J Orthop Sci. Jan 2007;12(1):55-60. [Medline].

20. Tse V. Neurological monitoring and management of intracranial hypertension. Semin Neurosurg. 2003;14:89-98.

21. Wijdicks EF. Uncal herniation in acute subdural hematoma: point of no return. Arch Neurol. Feb 2002;59(2):305. [Medline].

Keywords

brain herniation, Arnold-Chiari malformation, supratentorial, uncal herniation, brain displacement, mass effect, transtentorial herniation, transtentorial, tonsillar herniation, subfalcine herniation, extracranial herniation

Contributor Information and Disclosures

Author

Margaret Loh, MD, Staff Physician, Department of Radiology, Santa Clara Valley Medical Center
Margaret Loh, MD is a member of the following medical societies: Radiological Society of North America
Disclosure: Nothing to disclose.

Coauthor(s)

Mahesh R Patel, MD, Chief, MRI, Department of Diagnostic Imaging, Santa Clara Valley Medial Center
Mahesh R Patel, MD is a member of the following medical societies: American Roentgen Ray Society, American Society of Neuroradiology, and Radiological Society of North America
Disclosure: Nothing to disclose.

Medical Editor

Chi-Shing Zee, MD, Chief of Neuroradiology, Professor, Departments of Radiology and Neurosurgery, University of Southern California School of Medicine
Chi-Shing Zee, MD is a member of the following medical societies: American Society of Neuroradiology
Disclosure: Nothing to disclose.

Pharmacy Editor

Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand
Disclosure: Nothing to disclose.

Managing Editor

Robert L DeLaPaz, MD, Director, Professor, Department of Radiology, Division of Neuroradiology, Columbia University
Robert L DeLaPaz, MD is a member of the following medical societies: American Society of Neuroradiology, Association of University Radiologists, and Radiological Society of North America
Disclosure: Nothing to disclose.

CME Editor

Robert M Krasny, MD, Resolution Imaging Medical Corporation
Robert M Krasny, MD is a member of the following medical societies: American Roentgen Ray Society and Radiological Society of North America
Disclosure: Nothing to disclose.

Chief Editor

L Gill Naul, MD, Professor and Head, Department of Radiology, Texas A&M University College of Medicine; Chair, Department of Radiology, Chief, Section of Magnetic Resonance Imaging, Scott and White Memorial Hospital and Clinic
L Gill Naul, MD is a member of the following medical societies: American College of Radiology, American Medical Association, American Roentgen Ray Society, Radiological Society of North America, and Texas Medical Association
Disclosure: Nothing to disclose.

Clinical guidelines

Treatment: cerebral herniation. In: Guidelines for the prehospital management of severe traumatic brain injury, second edition.
Brain Trauma Foundation - Disease Specific Society
National Highway Traffic Safety Administration - Federal Government Agency [U.S.]. 2000 (revised 2007). 8 pages. NGC:006388

Guidelines for the management of severe traumatic brain injury. Intracranial pressure thresholds.
Brain Trauma Foundation - Disease Specific Society. 2000 (revised 2007). 4 pages. NGC:005776

Clinical trials

Establishing the Physiology of Syringomyelia

Genetic Analysis of the Chiari I Malformation

The Genetics of Chiari Type I Malformation

Related eMedicine topics

Posterior Fossa Tumors

Head Trauma (Pediatrics: Cardiac Disease and Critical Care Medicine)

Head Trauma (Trauma)

Chiari Malformation

Traumatic Brain Injury (TBI) - Definition, Epidemiology, Pathophysiology

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