brain herniation - boston university
Post on 16-Oct-2021
4 Views
Preview:
TRANSCRIPT
Brain HerniationAli Siddiqui
Bindu N Setty, MD
CASE HISTORY
27 yo male with unknown PMH presenting after an unwitnessed fall of about 25 feet, with 3 seizure-like episodes during transport, now unresponsive with GCS of 6 and fixed and dilated left pupil and right eye laterally deviated
Vitals: HR 40s SBP 120s Intubated
Labs: WBC 17.0 Hgb 13.2 Hct 39.3 Plt 262
Na 140 K 3.1 Cl 108 HCO3 21.0 BUN 13 Cr 0.97 Gluc 137
Toxicology: no Etoh
CT of Subdural Hematoma with Subfalcine Herniation
Axial CT without contrast shows hyperdense fluid collection around left hemisphere with 8mm midline shift to the right (arrow) and effacement of left lateral ventricle, consistent with subdural hemorrhage complicated by subfalcineherniation.
CT Head and Cervical Spine Without Contrast of Head Trauma
Coronal CT without contrast shows hyperdense fluid collection around left hemisphere with 8mm midline shift to the right (arrows) and effacement of left lateral ventricle, consistent with subdural hemorrhage complicated by subfalcine herniation.
CLINICAL FOLLOW UP
The patient underwent emergent decompressive left frontotemporoparietal craniectomy to relieve ICP.
Course subsequently complicated by persistent intraparenchymal hemorrhage and transcalvarial herniation
IN A NUTSHELL
Most important findings include
• Shift of septum pellucidum and midline structures to left or right
• Effacement of lateral ventricle ipsilateral to lesion causing mass effect
• Dilation of contralateral lateral ventricle
• More likely by anterior falx
Other relevant findings include:
• Depression of ipsilateral corpus callosum
• Elevation of contralateral cingulate gyrus
Potential complications include:
• Hydrocephalus
• Focal necrosis of cingulate gyrus
• ACA infarction
Remember: other herniations may co-occur, and should address increased ICP emergently
VOICE RAD CT and subfalcine herniation
by Dr. Setty(2020)
OLA
Infarction of which of the following arteries is a possible complication of a subfalcine herniation?
A. PCA
B. MCA
C. ACA
D. PICA
IMAGING SPECTRUM of DISEASE
• Integrated with discussion to follow
DISCUSSION
• This case is followed by other slides in which you can learn about the many other types of brain herniation syndromes. Many neurological conditions can cause mass effect, and the subsequent effects on the patient vary by the location of the mass and the anatomy affected. Knowing a little bit about the signs and symptoms of herniation syndromes can help when taking care of patients with neurological symptoms. It is also important to identify these syndromes as many are neurological emergencies due to progressive compromise of critical brain structures.
• General note on imaging for herniation: CT is often preferred due to speed even if MRI is comparable. However, MRI may be considered if additional risks are addressed and there is need for additional characterization of brain changes
Types of Herniation
• Supratentorial: • Transtentorial
• Descending types• Lateral herniation (often uncal herniation)
• Central herniation
• Subfalcine herniation• Transalar/transsphenoidal herniation
• Ascending or descending types
• Extracranial brain herniation• Paradoxical brain herniation
• Infratentorial: • Tonsillar herniation• Ascending transtentorial herniation
Quick anatomy review
Subfalcine herniation
• Also called midline shift or cingulate herniation
• Most common cerebral herniation
• Unilateral frontal, temporal or parietal lobe disease →medial mass effect→ ipsilateral cingulate gyrus under falx
• Severe herniation→ compression of corpus callosum and contralateral cingulate gyrus and ipsilateral lateral ventricle and foramen of Monro→ dilation of contralateral lateral ventricle
• Imaging: CT or MRI• Measure distance between line drawn in the midline at the level of foramen of Monro and
displaced septum pellucidum on an axial CT scan• Medial deviation of anterior falx• Depression of ipsilateral corpus callosum• Elevation or compression of contralateral cingulate gyrus• Compression of ipsilateral lateral ventricle• Dilation of contralateral lateral ventricle
Subfalcine herniation continued
• Complications• Hydrocephalus• Ipsilateral ACA infarct• Focal necrosis of cingulate gyrus
• Clinical signs of ACA infarct• Dysarthria• Aphasia• Contralateral motor weakness (Legs > arms/face)• Limb apraxia• Urinary incontinence
• Prognosis: good if midline shift less than 5mm; poor if over 15 mm
58 yo male presenting with sudden onset
left-sided weakness and facial droop found
to have right sided M1 MCA occlusion now
s/p tPA, transferred for thrombectomy, and
subsequently developed hemorrhagic
conversion of right MCA territory infarct with
mass effect.
CT shows large hemorrhage in right
frontotemporoparietal region and right
insula and basal ganglia, consistent with
hemorrhagic conversion of r infarct with
increase in size since prior imaging, with
internal worsening of mass effect, sulcal
effacement, effacement of right lateral and
third ventricles, effacement of basal
cisterns, midline shift increased to 2.1 cm
from 1.7cm prior, subfalcine herniation and
uncal herniation (not shown in image).
Diffuse cerebral edema. Focal dilation of
atria of both lateral ventricles and left
temporal horn, consistent with entrapment.
CT without contrast of subfalcine herniation before decompressive craniectomy
Case continued…
8 hours after prior imaging, now s/p right
frontotemporoparietal decompressive craniectomy
with evacuation of hematoma. CT shows
postsurgical changes, evolution of right MCA infarct,
new hypodense demarcation of right ACA and PCA
territories suggestive of infarct. Interval increase in
size of hemorrhage with multifocal pneumocephalus
consistent with clot evacuation and instrumentation.
Interval improvement of mass effect with decreased
effacement of right lateral and third ventricles and
basal cisterns. Now 1.4cm midline shift and
subfalcine herniation. Interval effacement of the atria
of the right lateral ventricle with prominence of the
atria of the left lateral ventricle with suggestion of
transependymal flow, concerning for ventricular
entrapment.
CT without contrast of subfalcine herniation after decompressive craniectomy
58 yo male presented with sudden onset left-sided weakness and facial droop found to have right sided M1 MCA occlusion s/p tPA, transferred
for thrombectomy, and subsequently developed hemorrhagic conversion of right MCA territory infarct with mass effect. Now s/p right
frontotemporoparietal decompressive craniectomy with evacuation of hematoma complicated by acute right ACA and PCA infarcts 5 days ago.
MRI shows post surgical changes with partial herniation of right cerebral hemisphere through craniectomy defect. Diffuse sulcal effacement,
edema, and loss of gray-white differentiation in right ACA, MCA, and PCA territories. In the right frontal, temporal, and parietal lobes and the
right thalamus/thalamocapsular junction, there is diffusely increased T2/FLAIR signal with confluent hyperintense DWI signal with patchy
ADC correlates, likely corresponding to subacute infarcts (not shown).
CT without contrast of ACA and PCA infarcts after herniation
Uncal and lateral herniations
• Innermost part of temporal lobe, the uncus, is displaced past tentorium cerebelli → brainstem and midbrain compression
• Clinical presentation
• Anterior subtype• Ipsilateral dilated pupil due to oculomotor nerve compression• Ptosis due to oculomotor nerve palsy• Lateral deviation from unopposed abducens input• Vertical gaze palsy if compression of the rostral interstitial nucleus of the MLF • Altered mental status due to compression of reticular activating system• Contralateral hemiparesis• Posterior subtype → tectum/superior colliculus involvement → Parinaud syndrome• May see ipsilateral hemiparesis due to Kernohan notch phenomenon/false localizing sign due to
compression of contralateral cerebral peduncle and descending corticospinal tract• Can compress ipsilateral PCA → homonymous hemianopsia
Uncal and lateral herniations continued
• Imaging: MRI or CT (though harder to see actual herniation on CT)• Medial displacement of uncus and parahippocampal gyrus of temporal lobes and temporal horn of lateral ventricle• Early sign: encroachment of ipsilateral suprasellar cistern • Effacement of all basal cisterns• Widening of ipsilateral cerebellopontine angle• Asymmetric inferior midbrain displacement and effacement• Ipsilateral midbrain hemorrhage• Inferomedial displacement of posterior communicating and PCA• If bilateral → complete obliteration suprasellar cistern and midbrain effaced and displaced inferiorly
• If diagnosed – life threatening and should notify referring physician!
• Complications: • Focal necrosis of uncus and brainstem ischemia• Duret hemorrhage (poor prognosis)• Kernohan phenomenon• PCA infarct• Respiratory failure
CT without contrast of uncal herniation
75 yo male presenting with right sided facial numbness and mastication muscle weakness, and exertional chest pain. CT shows large right-sided hyperdense subdural collection causing 1.3 cm leftward shift, producing a leftward subfalcine herniation (not shown), mild right uncal herniation with suggestion of impending downward transtentorialherniation; near complete effacement of right lateral ventricle with dilatation of left ventricle’s temporal horn, and significant effacement of 3rd ventricle; hypodensity by right posterior temporal occipital region.
CT without contrast of uncal herniation
58 yo male presenting with sudden onset left-sided
weakness and facial droop found to have right sided M1
MCA occlusion now s/p tPA, transferred for thrombectomy,
and subsequently developed hemorrhagic conversion of
right MCA territory infarct with mass effect.
CT now shows large hemorrhage in right
frontotemporoparietal region and right insula and basal
ganglia, consistent with hemorrhagic conversion of right
MCA territory infarct with increase in size since prior
imaging, with internal worsening of mass effect, sulcal
effacement, effacement of right lateral and third ventricles,
effacement of basal cisterns, midline shift increased to 2.1
cm from 1.7cm prior, subfalcine herniation (not shown
here) and bilateral uncal herniation. Diffuse cerebral
edema. Focal dilation of atria of both lateral ventricles
and left temporal horn, consistent with entrapment.
CT without contrast of descending transtentorialherniation
86 yo female who presented with drooling and seizure like activity an hour after having been at her baseline, now unresponsive with forced R gaze deviation and weakness of L side, with hypertension and respiratory distress, now admitted. CT shows worsening right hemispheric swelling, subfalcineherniation to the left at 22mm, new left ACA infarction due to herniation, severe right inferior transtentorial herniation with edematous brain tissue in the right perimesencephalic cistern and in the supracerebellar cistern, effacement of right lateral ventricle and right temporal horn and leftward displacement of 3rd
ventricle with enlargement of left lateral ventricle with periventricular edema, indicating obstructive hydrocephalus; previous subarachnoid hemorrhages
Ascending transtentorial herniation
• Clinical presentation: nausea/vomiting, rapid decrease in level of consciousness
• Imaging: CT or MRI• Early signs: compression and slight flattening of quadrigeminal plate cistern
• Further herniation → triangular or “squared off” appearance to quadrigeminal and superior cerebellar cisterns
• Severe herniation → efface cisterns and flattens posterior third ventricle
• May see obstructive hydrocephalus
• May also see reversal of posteriorly-directed convexity of colliculi –> “toothy smile” of quadrigeminal cistern becomes a “toothy frown”
• Followed by loss of quadrigeminal plate and superior cerebellar cisterns, and posterior flattening of 3rd ventricle
• “spinning top” appearance to midbrain
• Secondary signs: • Encroachment on the retrosellar/interpeduncular subarachnoid space
• Anterior displacement of brainstem
• Obliteration of pontine cisterns
• Anterosuperior displacement and compression of ambient cisterns by herniating vermis
• Complications: PCA or superior cerebellar artery infarct
CT of ascending trans-tentorial herniation and tonsillar herniation54 yo female presenting unresponsive
after fall down 13 steps after
consuming beer and clonopin,
transferred to BMC with prior CT
showing skull fracture and intracranial
hemorrhage. Clinically unconscious,
without vestibulo-ocular reflexes, no
corneal or gag reflexes, no response
to pain, nonreactive pupils.
Subsequently coded in the scanner.
CT shows extensive left-sided skull
fractures with associated left
cerebellar hemorrhage with
associated subarachnoid and subdural
components, resulting in ascending
transtentorial and inferior tonsillar
herniation. There is dilatation of the
temporal horns of the lateral ventricles
consistent with developing
hydrocephalus. The basilar cisterns
and 4th ventricle are effaced. A large
soft tissue hematoma overlying the left
parieto-occipital lobe.
Central herniation
• Descent of midbrain and diencephalon
• More likely if bilateral or midline mass effect
• Clinical presentation: rostral to caudal progression of deficits due to brainstem dysfunction• Flexor posturing (decorticate) → extensor posturing (decerebrate) → rigidity/paralysis → abnormal respiration due
to compression of medulla→ death
• Imaging – CT or MRI• Effacement of peri-mesencephalic cisterns
• Descent of diencephalon and lateral herniation of temporal lobes
• Oblong deformity of midbrain
• Descent of quadrigeminal plate and basilar artery
• Flattening of pons against clivus
• Complications• Duret hemorrhages
• PCA infarct
• Hydrocephalus
Tonsillar herniation
• Inferior descent of cerebellar tonsils below foramen magnum
• Also called coning
• May be seen congenitally (Chiari I malformation) which should not be confused with this acute process.
• Risk compression of brainstem against clivus• May affect cardiac and respiratory centers in the pons and medulla
• Imaging: MRI (preferred) or CT• Inferior descent tonsils past foramen magnum• Effacement of CSF cisterns around brainstem• Can see obstructive supratentorial hydrocephalus
• Complications• Cerebellar infarcts via posterior inferior cerebellar artery compression• Sudden respiratory arrest
MRI with contrast of tonsillar herniation
54 yo female presenting with intermittent frontal headaches and subjective dizziness with PMH of breast cancer treated by mastectomy but otherwise normal neurologic exam. MRI shows a 2.3x2.7x2.3cm enhancing mass centered in right cerebellum (not shown) and cerebellar vermis with surrounding edema, partial effacement of cerebral aqueduct and 4th ventricle and herniation of the cerebellar tonsils into foramen magnum by 1.6cm
Transalar/Transsphenoidal herniation
• Herniation in middle cranial fossa across greater sphenoid wing → compress against sphenoid bone
• Descending variant• Mass effect from the frontal lobe• Posterior and inferior displacement of posterior aspect of frontal lobe orbital surface• Small herniation affects orbital gyri• Larger herniation may involve the gyrus rectus• Can compress MCA against sphenoid ridge →MCA territory infarct
• Ascending variant• Middle cranial fossa or temporal lobe mass effect• Displacement of temporal lobe medially and superiorly across sphenoid ridge• Can compress supraclinoid ICA against anterior clinoid process → ACA and MCA territory infarct
• Imaging: MRI preferred, though CT may show indirect signs, like anterior displacement of ipsilateral MCA
Extracranial brain herniation
• Herniation brain external to the calvaria
• Often due to post-traumatic or post-surgical skull defect
• May be result of craniectomy for patients who needed to be treated for increased ICP
• Eventually needs surgical reduction due to risk of ischemia and venous infarct from occluded cortical veins
CT Brain without Contrast of transcalvarialherniation
• CT without contrast of the brain of a 27yo male shows postsurgical changes s/p left craniectomy complicated by transcalvarial herniation and heterogenous hyperdense intraparenchymal hemorrhages in the left frontal, temporal, and parietal lobes with surrounding vasogenic edema, severe effacement of left ventricle and prominence of right lateral and third ventricles. Complication includes transcalvarial and subfalcineherniation.
Paradoxical brain herniation
• Also called sinking skin flap syndrome or syndrome of the trephined
• Pathology: atmospheric pressure exceeds ICP → displacement of brain at craniectomy site into intracranial space
• Pressure imbalance often due to CSF drainage or lumbar puncture• May cause subfalcine or transtentorial herniations
• Clinical presentation: ranges from asymptomatic to acute neurological degeneration, along with symptoms from other herniations
• Imaging: CT or MRI• Marked concavity of skin flap
• Mass effect (effacement of superficial sulci, buckling of gray-white matter)
• Paradoxical midline shift contralateral to craniectomy site
• Treatment & prognosis: neurosurgical emergency!• Put in Trendelenburg to increase ICP• Correct underlying cause (CSF drains, LP sites)• Consider cranioplasty
CT Brain without Contrast of paradoxical brain herniation
46 yo male who presents 6 weeks after a left decompressive craniectomy for left MCA stroke complicated by intraparenchymal hemorrhages, now with altered orientation and concavity of the brain beneath the helmet. CT without contrast shows postsurgical changes, encephalomalacia from prior left ICA infarctions and in right parietal and occipital lobes; 6mm paradoxical midline shift to the right with sunken skin flap but no effacement of ambient and basilar cisterns (not shown), concerning for sunken flap syndrome that may progress to paradoxical herniation. Right frontal lobe gliosis from prior ventriculostomy catheter tract. Ex vacuo dilatation of lateral horn of left ventricle and occipital horn of right ventricle.
LINKS AND REFERENCESNational Guidelines
N/A
Consistent References: 1. https://radiopaedia.org/articles/subfalcine-herniation?lang=us2. https://radiopaedia.org/articles/uncal-herniation-1?lang=us3. https://radiopaedia.org/articles/kernohan-phenomenon?lang=us4. https://radiopaedia.org/articles/transtentorial-herniation?lang=us5. https://radiopaedia.org/articles/ascending-transtentorial-herniation?lang=us6. https://radiopaedia.org/articles/central-herniation?lang=us7. https://radiopaedia.org/articles/tonsillar-herniation?lang=us8. https://radiopaedia.org/articles/extracranial-brain-herniation?lang=us9. https://radiopaedia.org/articles/paradoxical-brain-herniation?lang=us10. https://radiopaedia.org/articles/transalar-herniation?lang=us11. https://radiopaedia.org/articles/cerebral-herniation?lang=us
12. https://radiopaedia.org/articles/anterior-cerebral-artery-aca-infarct?lang=us
Other Journals and Texts
1. https://emedicine.medscape.com/article/337936-overview
2. https://www-ajronline-org.ezproxy.bu.edu/doi/abs/10.2214/ajr.130.4.755
3. https://www-ajronline-org.ezproxy.bu.edu/doi/pdfplus/10.2214/ajr.165.4.7677003
4. https://epos.myesr.org/poster/esr/ecr2020/C-15306/
5. https://www-ncbi-nlm-nih-gov.ezproxy.bu.edu/books/NBK542246/
6. https://epos.myesr.org/poster/esr/ecr2019/C-2732/findings%20and%20procedure%20details
7. https://www.nuemblog.com/blog/2018/4/20/emergency-neuroimaging
8. https://en.wikipedia.org/wiki/Dura_mater#/media/File:Sobo_1909_589.png
Additional Resources for Students:
https://sugarytooth.wordpress.com/2017/09/02/basal-cisterns/
https://slideplayer.com/slide/7932469/
https://www.youtube.com/watch?v=Rp96BYmikrw
https://www.youtube.com/watch?v=nFwJic2mYCU
Videos
OLAS
top related