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KEY FACTS

Terminology
- Headache caused by ↓ intracranial CSF pressure
Imaging
- Classic imaging quintet - Downward displacement of brain through incisura (brain "sagging") - Diffuse dural thickening/enhancement - Veins, dural sinuses distended - Engorged pituitary gland - Subdural hygromas/hematomas
- Lack of 1 or more of 5 classic findings does not preclude diagnosis
- Cranial MR diagnostic in 90% but 10% normal
Top Differential Diagnoses
- Meningitis
- Meningeal metastases
- Chronic subdural hematoma
- Dural sinus thrombosis
- Postsurgical dural thickening
- Idiopathic hypertrophic cranial pachymeningitis
Clinical Issues
- Severe headache (orthostatic, persistent, pulsatile, or even associated with nuchal rigidity)
- Uncommon: Cranial nerve (CN) palsy (e.g., abducens), visual disturbances
- Rare: Severe encephalopathy with disturbances of consciousness
- Profile: Young/middle-aged adult with orthostatic headache
- Opening pressure often < 6 cm H₂O but normal pressure common and should not exclude diagnosis
Diagnostic Checklist
- Frequently misdiagnosed clinically; imaging is key to diagnosis - Do not misdiagnose intracranial hypotension as Chiari 1! - Surgery can exacerbate symptoms; in rare cases can be fatal
- Only rarely are all classic clinical and imaging findings of spontaneous intracranial hemorrhage present in same patient

TERMINOLOGY

Abbreviations
- Intracranial hypotension (IH)
Definitions
- Headache caused by ↓ intracranial cerebrospinal fluid (CSF) pressure

IMAGING

General Features

Best diagnostic clue

- Classic imaging quintet
        - Downward displacement of brain through incisura (brain "sagging")
        - Diffuse dural thickening/enhancement
        - Veins, dural sinuses distended
        - Subdural hygromas/hematomas
        - Engorged pituitary gland
- Lack of 1 or more of 5 classic findings does not preclude diagnosis
- Cranial MR diagnostic in 90% of cases but 10% normal

Location

- Pachymeninges (dura)
        - Both supra- and infratentorial
        - May extend into internal auditory canals
        - Spinal dura, epidural venous plexuses may be involved

Morphology

- Dural enhancement is smooth, not nodular or "lumpy-bumpy"

CT Findings

NECT

- Relatively insensitive; may appear normal
- Look for effaced suprasellar/basilar cisterns, "fat" midbrain/pons
- ± thick dura
- ± subdural fluid collections
        - Usually bilateral
        - CSF (hygroma) or blood (hematoma)
- Atria of lateral ventricles may appear deviated medially, abnormally close ("tethered") to midline
- Skull base defect on bone CT rarely causes spontaneous IH

CECT

- Diffuse dural thickening, enhancement

MR Findings

T1WI

- Sagittal view shows brain descent in 40-50% of cases
        - "Sagging" midbrain
                  - Midbrain displaced inferiorly below level of dorsum sellae
                  - Pons may be compressed against clivus
        - ↓ angle between peduncles, pons
        - Caudal displacement of tonsils in 25-75%
                  - Caution: Do not misdiagnose as Chiari 1 malformation; look for other imaging features of brain "sagging"
        - Optic chiasm, hypothalamus draped over sella
        - Pituitary enlarged above sella in 50%
        - ↓ angle between internal cerebral veins (ICVs), vein of Galen
        - ↓ vertical distance between pons, mammillary bodies
- Axial
        - Suprasellar cistern crowded/effaced
        - Midbrain, pons appear elongated ("fat" midbrain)
        - Interpeduncular angle ↓ (avg = 25⁰)
        - Temporal lobes herniated over tentorium, into incisura
        - Lateral ventricles small, often distorted
                  - Atria pulled medially by downward displacement of midbrain
- Coronal
        - Severe cases show ↓ venous angle (< 120°) between roofs of lateral ventricles
- Bilateral subdural fluid collections in 35%
        - 70% hygromas (clear fluid collects within dural border cell layer)
        - 10% hematomas (blood of variable signal intensity)

T2WI

- Thickened dura usually hyperintense
- Subdural fluid (variable signal)

FLAIR

- Hyperintense dura, subdural fluid
- Hyperintense midbrain corticospinal tracts in 55%

T2* GRE

- May bloom if hemorrhage present
- Rare: Superficial siderosis

T1WI C+

- Diffuse, smooth intense dural enhancement in 85%
        - Often extends into cerebellopontine angles (CPAs)
- Veins/dural sinuses distended (convex margins)

Ultrasonographic Findings

Color Doppler

- Enlarged superior ophthalmic veins with higher mean maximum flow velocity

Angiographic Findings
- Cortical, medullary veins may be diffusely enlarged
Nonvascular Interventions
- Spinal imaging (site of leak identified in ≈ 50%) - Digital subtraction myelography > dynamic CT myelography - Type 1 leaks = dural tear, extradural CSF collection - Almost always associated with extradural CSF collection - Adjacent bony abnormality (osteophyte, calcification) common - 1a leak = ventral - 1b = posterolateral - Type 2 leaks = meningeal diverticula > 8 mm - 2a = single or multiple diverticula - 2b = complex meningeal diverticula or dural ectasia - Type 3 leaks = direct CSF-venous fistulas - Never show extradural CSF collection - Single vein or network of dilated veins around root sleeve - Type 4 leaks = without confirmed source on dedicated spinal imaging - Extradural CSF in 50%; 50% have no evidence of extradural CSF
Nuclear Medicine Findings
- Radionuclide cisternography (RNC) - Direct findings: Focal accumulation of radioactivity outside of subarachnoid space at leakage site - Indirect findings - Rapid washout from CSF space - Early appearance of activity in kidneys, urinary bladder - Poor migration of isotope over convexities

Imaging Recommendations

Best imaging tool

- Contrast-enhanced cranial MR for diagnosis
- Dynamic CT myelography for leak localization

Protocol advice

- Search for actual leakage site only if
        - 2 technically adequate blood patches fail
        - Posttraumatic leak is suspected

DIFFERENTIAL DIAGNOSIS

Meningitis
- Pia-subarachnoid enhancement > dura-arachnoid
Meningeal Metastases
- Enhancement usually thicker, irregular ("bumpy")
Chronic Subdural Hematoma
- Look for enhancing membranes with blood products
Dural Sinus Thrombosis
- Look for thrombosed sinus (empty delta sign, etc.)
Postsurgical Dural Thickening
- Look for other postoperative findings (e.g., burr holes)
- May occur almost immediately after surgery, persist for months/years
Idiopathic Hypertrophic Cranial Pachymeningitis
- Headache usually not orthostatic
- May cause bone invasion

PATHOLOGY

General Features

Etiology

- Dural thickening, enhancement due to venous engorgement
- Common cause of IH = spontaneous spinal CSF leak
        - Weak dura ± arachnoid diverticulae common
        - Aberrant extracellular matrix with abnormalities of fibrillin-containing microfibrils
- Most (but not all) cases caused by reduced CSF pressure precipitated by
        - Surgery (CSF overshunting) or trauma (including trivial fall)
        - Vigorous exercise or violent coughing
        - Diagnostic lumbar puncture
        - Spontaneous dural tear, ruptured arachnoid diverticulum
        - Severe dehydration
        - Disc herniation or osteophyte (rare)
- Pathophysiology = Monro-Kellie doctrine
        - CSF, intracranial blood volume vary inversely
        - In face of low CSF pressure, dural venous plexuses dilate

Associated abnormalities

- Dilated cervical epidural venous plexus, spinal hygromas, retrospinal fluid collections
- Typical
        - Low opening pressure, < 6 cm H₂O
        - CSF frequently shows pleocytosis, ↑ protein
- Variant
        - Opening pressure occasionally normal (CSF hypovolemia rather than hypotension)
- Stigmata of systemic connective tissue disorder found in up to 2/3 of patients
        - Marfan, Ehlers-Danlos type 2
        - Clinical findings = minor skeletal features, small joint hypermobility, etc.; may be subtle

Gross Pathologic & Surgical Features
- Surgical specimen generally unremarkable with grossly normal-appearing dura
- Spinal meningeal diverticula (often multiple), dural holes/rents common
- No specific leakage site identified at surgery in at least 50%
Microscopic Features
- Meningeal surface normal - No evidence for inflammation or neoplasia
- Inner surface - Layer of numerous delicate, thin-walled dilated, vessels often attached to inner surface - Nests of meningothelial cells may be prominent, should not be misinterpreted as meningioma - May show marked arachnoidal, dural fibrosis if longstanding

CLINICAL ISSUES

Presentation

Most common signs/symptoms

- Severe headache (orthostatic, persistent, pulsatile, or even associated with nuchal rigidity)
- Uncommon: Cranial nerve (CN) palsy (e.g., abducens), visual disturbances
- Rare: Severe encephalopathy with disturbances of consciousness

Clinical profile

- Young/middle-aged adult with orthostatic headache
        - Lack of orthostatic headache should not exclude spontaneous IH!
- Opening pressure often < 6 cm H₂O but normal pressure common and should not exclude diagnosis

Demographics
- Age
```
- Peak in 3rd, 4th decades
```
Natural History & Prognosis
- Most IH cases resolve spontaneously - Dural thickening, enhancement disappears; midline structures return (ascend) to normal position
- Rare: Coma, death from severe intracranial herniation
Treatment
- "Blind" (nontargeted) epidural blood patch (EBP) - Immediate: Replaces fluid (tamponade effect) - Emergent intrathecal saline infusion if patient severely encephalopathic, obtunded - Negative pressure gradient within epidural space - Causes rostral flow of injected blood - Proximal flow of blood products has "plug" effect - Underreported complication = rebound intracranial hypertension
- Targeted vs. blind EBP - Targeted EBP 87% successful; 52% nontargeted - 2-site EBP may be as efficacious as targeted EBP
- Surgery if blood patch fails (usually large dural tear) or subdural hematomas with acute clinical deterioration

DIAGNOSTIC CHECKLIST

Consider
- Frequently misdiagnosed clinically; imaging is key to diagnosis - Do not misdiagnose IH as Chiari 1! - Surgery can exacerbate symptoms; in rare cases can be fatal
Image Interpretation Pearls
- Only rarely are all classic findings of IH present in the same patient
- Look for enlarged spinal epidural venous plexuses

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References

Selected References

Cases

{'cases': [{'authors': [{'key': 'bee1f359-33fb-4cba-9e6b-ed1ca1842439', 'value': 'Jeffrey S. Ross, MD'}], 'caseVersionId': '08037059-66e8-40f3-97d5-33a03f1f61ec', 'description': 'C4-5 level CSF leaks along roots sleeves.\n\nMR of the brain (#1-3) shows typical diffuse dural enhancement of intracranial hypotension.\n\nPost myelographic CT images (#4-6) show contrast extending along the roots sleeves bilaterally at C4-6 out into the cervical plexus (arrows).\n\nPatient was treated with multiple blood patches.\n\nPatients with persistent and "occult" CSF leaks do not infrequently have multiple sources involving the cervical-thoracic junction or thoracic spine. Myelography, myelo CT, nuclear cisternography and heavily T2-weighted MR imaging may all be used to try and localize the source of leak.', 'history': 'Severe positional headache.', 'imagePoolId': '4434b392-889b-4575-8190-0b401b9ae3c1', 'name': 'Bilateral cervical root sleeve CSF leaks', 'teachingPoint': None}, {'authors': [{'key': '5cff4116-3654-4b3a-bb75-5ebe0b8c9850', 'value': 'Anne G. Osborn, MD, FACR'}], 'caseVersionId': '7fc99261-e3c8-4d04-af7d-99044309e2fe', 'description': "Sagittal T1WI (#1) shows several interesting findings. The midbrain appears "slumped", and the angle between it and the pons (usually almost 90 degrees) appears much more "closed" than normal (open arrow). The cerebellar tonsil lies well below the foramen magnum (white arrow). The pituitary gland is convex upwards, and the optic chiasm is draped over the dorsum sellae (curved arrow). Axial T1WI (#2) through the suprasellar cistern shows tissue- not CSF- within the suprasellar area (arrows). The temporal lobes appear herniated medially (curved arrows), and the surface sulci are obliterated. The axial T2WI (#3) shows that the "flow void" of the superior sagittal sinus (arrow) is unusually large and has convex margins.\n\nThe post-contrast axial (#4-7) and coronal (#8-9) T1WIs are very interesting. They show diffuse dural thickening and enhancement (open arrows), and all the dural sinuses are enlarged, with convex-appearing margins (arrows). Even the superior ophthalmic veins (curved arrows, #5) appear unusually prominent.\n\nSagittal T2WI (#10) through the cervical spine shows very prominent epidural spaces (arrows), probably secondary to engorgement of the epidural venous plexuses.\n\nComment: The low tonsils are round, not pointed (as would be seen in a Chiari 1 malformation). The "fat" pituitary, "slumped" midbrain, diffuse dural thickening and enhancement, and engorged venous sinuses with convex (not concave) margins all indicate intracranial hypotension.\n\nThe patient's symptoms resolved after epidural blood patch, and follow-up MR (not shown) appeared normal.", 'history': 'Worsening postural headaches.', 'imagePoolId': 'a6aae8a1-3c99-4ca6-8c55-239c1fad6ec7', 'name': 'Amazing enlargement of venous sinuses', 'teachingPoint': None, 'demographics': '32 Years old female'}, {'authors': [{'key': '5cff4116-3654-4b3a-bb75-5ebe0b8c9850', 'value': 'Anne G. Osborn, MD, FACR'}], 'caseVersionId': 'f806495a-4edd-416b-9d5d-b395d9a5b417', 'description': 'Intracranial hypotension causes venous engorgement of the dura. Occasionally, it may cause pituitary enlargement and mimic adenoma or pituitary hyperplasia, as happened in this case.\n\nSagittal T1WI MR (#1), demonstrates sagging midbrain. Note upward bulging pituitary gland with draping of the optic chiasm over the gland (arrow). Coronal T1 C+ MR through the sella (#2), shows an enlarged pituitary gland (open arrow) with mild dural thickening (arrows). Coronal post-contrast T1 weighted MR (#3), shows the typical dural thickening and venous engorgement of classic intracranial hypotension.', 'history': 'Intractable headaches relieved by lying down.', 'imagePoolId': '7252d1cc-cefb-47fd-a08a-3a54861f14cd', 'name': 'Enlarged pituitary gland', 'teachingPoint': None, 'demographics': '48 Years old female'}, {'authors': [{'key': '5cff4116-3654-4b3a-bb75-5ebe0b8c9850', 'value': 'Anne G. Osborn, MD, FACR'}], 'caseVersionId': 'f0e41a00-8504-4ea8-a1f1-09123ac2ce47', 'description': 'Sagittal T1WI (#1) shows slight inferior displacement of the tonsils below the foramen magnum (arrow) and decreased distance between the optic chiasm and sella (curved arrow). The midbrain is not obviously "slumping." FLAIR scan (#2) shows hyperintense thickened dura (arrows). Axial (#3) and coronal (#4, 5) show diffusely enhancing, smoothly thickened dura. \n\nThis is a case where the central inferior midbrain displacement is minimal but the dural engorgement and thickening is relatively striking. Intracranial hypotension (in this case, spontaneous) may display a spectrum of findings, not all of which are present in every case.', 'history': 'Headaches. No history of trauma.', 'imagePoolId': 'c4de09d4-8e1a-456e-9b77-e057efe38740', 'name': 'Mild slumping midbrain, striking dural enhancement', 'teachingPoint': None}, {'authors': [{'key': '5cff4116-3654-4b3a-bb75-5ebe0b8c9850', 'value': 'Anne G. Osborn, MD, FACR'}], 'caseVersionId': '98e82d35-9959-47fa-95dc-2ba5e8500712', 'description': "Intracranial hypotension is typically caused by CSF leak. History of trauma or other predisposing condition is often lacking and the diagnosis is established when patients are imaged for headache. Contrast-enhanced scans should be done when sagittal T1WI MR suggests "slumping midbrain" (as was seen in this case).\n\nSagittal T1 weighted MR scan shows the classic appearance of "slumping midbrain," with the junction between the midbrain and pons displaced inferiorly below the level of the dorsum sellae (#1, arrow). The suprasellar cistern may be effaced, with the optic chiasm and hypothalamus draped over the dorsum (#1, open arrow). Tonsillar herniation is common but is minimal in this case. Axial pre-contrast T1WI shows the suprasellar cistern is effaced and both temporal lobes have herniated medially over the tentorial incisura (#2, arrows). Axial post-contrast T1WIs (#3-4) show diffuse dural enhancement that extends into the internal auditory canals. Diagnosis was intracranial hypotension and a blood patch was performed. Patient's symptoms resolved.\n\nFollow-up scan (#5-6) performed 12 months later was normal. Note normal position of the pons and optic chiasm (#5) and resolution of abnormal dural thickening and enhancement (#6) as compared to the original examination.", 'history': 'Intractable chronic headaches, relieved in supine position.', 'imagePoolId': '1df83528-3d6c-470c-8e8b-e1be7a4e6567', 'name': 'Classic with resolution s/p blood patch', 'teachingPoint': None}, {'authors': [{'key': '5cff4116-3654-4b3a-bb75-5ebe0b8c9850', 'value': 'Anne G. Osborn, MD, FACR'}], 'caseVersionId': '7eff3cb8-762c-48f0-872a-5825f9f21379', 'description': "Intracranial hypotension can be life-threatening if the downwards herniation becomes severe or if subdural hematomas develop.\n\nCoronal T2WI MR (#1), shows the fluid collections are SDHs of different ages. Drainage of the SDHs without recognizing the underlying diagnosis of spontaneous IH caused worsening of the patient's symptoms. Sagittal T1 C+ MR (#2), shows obliteration of suprasellar cistern, sagging and fat midbrain with closed angle between peduncles/pons (arrow), dural enhancement, tonsillar descent. Axial T1 C+ MR (#3), shows diffuse dural enhancement, hypodense extra-axial fluid collections, small ventricles with medial deviation of choroid and ICVs (arrows) caused by midbrain descent. Coronal T1 C+ MR (#4), shows subdural fluid (open arrows) with diffuse dural thickening extending into both IACs (arrows). Lateral ventricles are pulled towards the midline.", 'history': 'Severe postural headaches for several weeks, presented with drowsiness and decreased mental status.', 'imagePoolId': '173f8ea3-1bd0-4b35-a298-bb631d7829bb', 'name': 'Classic MR, severe', 'teachingPoint': None}], 'caseType': 'typical', 'name': 'TYPICAL'}
{'cases': [{'authors': [{'key': 'bee1f359-33fb-4cba-9e6b-ed1ca1842439', 'value': 'Jeffrey S. Ross, MD'}], 'caseVersionId': 'a3fd8b37-12fd-4db2-9cee-66847267a893', 'description': 'Brain study (#1, 2) show typical appearance of intracranial hypotension with diffuse dural enhancement both above and below the tentorium. Radionuclide cisternography (anterior view) (#3) show a large amount of activity spilling from the spinal thecal sac into the right chest (arrows). CT following myelogram (#4-12) shows leakage of contrast from the thoracic thecal sac through the right T4-5 neural foramen into the right pleural space (arrows). More inferior axial slice (#8, 12) shows prominent epidural soft tissue due to distended epidural veins (curved arrows). MR study (#13-17) shows diffuse dural thickening and enhancement (arrows, #13-14), and the site of CSF leak extending from the right neural foramen (#15-17). Patient required right laminectomy at T4 to repair the leak.', 'history': 'Recent right thoracotomy for lung carcinoma, now with unremitting severe postural headache.', 'imagePoolId': 'abe41d93-65e8-42fe-b525-1714847527e8', 'name': 'CSF leak following thoracotomy', 'teachingPoint': None, 'demographics': '50 Years old female'}, {'authors': [{'key': '33151213-01b2-4542-9105-342e006b3915', 'value': 'H. Ric Harnsberger, MD'}], 'caseVersionId': '57d36d6f-00c4-4fb7-887c-4c81c842cc8a', 'description': 'Variant CT-MR case of arachnoid granulation in the area of the petromastoid canal (subarcuate canaliculus) with associated CSF leak, intracranial hypotension, and multiple episodes of meningitis.\n\nAxial bone CT images (#1-2) reveal a large arachnoid granulation in the roof of the petrous apex (arrow, #1) and opacification of the middle ear and mastoid (curved arrows, #1-2). CT with intrathecal contrast shows opacified CSF traversing the arachnoid granulation (arrows, #3-4) into temporal bone air cells and into the middle ear cavity (curved arrow, #4).\n \nAn axial T2 MR image (#5) demonstrates fluid signal in the middle ear and mastoid (curved arrows) from CSF leak into these areas. Axial (#6) and coronal (#7-9) T1 C+ fat-saturated MR images show the non-enhancing arachnoid granulation in the petrous apex (arrows, #6-9). Diffuse dural enhancement (open arrows, #7-9) most likely is secondary to intracranial hypotension from the CSF leak. Pia-arachnoid enhancement seen along the nerves of the IAC (curved arrows, #9) results from the recurrent meningitis episodes.', 'history': 'Patient presents with recurrent episodes of meningitis; skull base CT shows an abnormality in the right petrous apex. CT with intrathecal contrast and MR completed for further evaluation.', 'imagePoolId': 'c602dfeb-e877-4a87-871c-c610cb8b21a6', 'name': 'Variant AG with CSF leak and intracranial hypotension', 'teachingPoint': None, 'demographics': '75 Years old female'}, {'authors': [{'key': '5cff4116-3654-4b3a-bb75-5ebe0b8c9850', 'value': 'Anne G. Osborn, MD, FACR'}], 'caseVersionId': '81585ec2-bd1f-4481-8632-ff6b10bb2e7d', 'description': 'Sagittal T1WI (#1) shows a slightly "slumping" brainstem with the hypothalamus and optic chiasm draped over the dorsum sellae (curved arrow). Note absence of tonsillar herniation. Axial T1WI (#2) shows both temporal lobes are herniated medially over the tentorium (arrows) and there is complete effacement of the suprasellar subarachnoid cistern, seen here as absence of CSF. Axial T2WI through the posterior fossa (#3) shows a hyperintense band (arrows) around both cerebellar hemispheres (arrows). Post-contrast axial (#4-5) T1 C+ scans show diffuse dural enhancement that surrounds the cerebral and cerebellar hemispheres and even extends into both internal auditory canals (#4, arrows).\n\nNot all findings of intracranial hypotension are present in every case. This example is unusual because it lacks the downwards tonsillar herniation (sometimes misnamed "acquired Chiari I") that is seen in most cases.', 'history': 'Severe headaches relieved by supine position.', 'imagePoolId': '00a36dac-2e02-40ae-9c43-499956f81a67', 'name': 'Desc transtentorial herniation', 'teachingPoint': None}], 'caseType': 'variant', 'name': 'VARIANT'}

Images

Selected Images

Graphic shows IH with distended dural sinuses and enlarged pituitary and herniated tonsils . Central brain descent causes midbrain slumping, inferiorly displaced pons, closed pons-midbrain angle , and splenium depressing ICV/vein of Galen junction .

T2 MR in a 57-year-old man treated for migraine headaches shows severe midbrain slumping , downwardly displaced cerebellar tonsils , and "draping" of the hypothalamus over the dorsum sellae with mammillary bodies below the dorsum.

Sagittal T1 C+ FS MR in the same patient shows the severe midbrain slumping and inferiorly displaced tonsils. In addition, the pituitary gland appears "fat" and the dural venous sinuses are engorged .

Axial T1 C+ FS MR in the same patient shows a "fat" midbrain/pons , prominent superior ophthalmic veins , and engorged, outwardly convex transverse/sigmoid sinuses . No subdural hematomas were identified. Severe IH was treated successfully with a blood patch.

Axial NECT in a 55-year-old man with a severe headache in the ER shows downward herniation of both cerebellar tonsils through the foramen magnum.

More cephalad NECT in the same patient shows effacement of all basal cisterns, especially the suprasellar cistern . The midbrain appears "fat" . The imaging findings are suggestive of IH.

Sagittal T1WI MR in the same patient shows changes of severe IH with midbrain slumping , downward tonsillar displacement , "fat" pituitary gland , and "draping" of the optic chiasm/hypothalamus over the dorsum sellae .

Axial T2WI MR in the same patient shows the inferiorly displaced hypothalamus and 3rd ventricle obliterating the suprasellar cistern . The midbrain appears "fat" and elongated.

Axial T1 C+ FS MR in the same patient shows smooth, diffuse dura-arachnoid enhancement , and an engorged, outwardly convex superior sagittal sinus .

Coronal T1 C+ FS MR in the same patient shows the diffuse dura-arachnoid enhancement extends into both internal auditory canals . The lateral ventricles have a more acute angle and appear "pulled down" toward the incisura. An epidural blood patch relieved the symptoms.

Additional Images

Sagittal T1WI C+ MR in a patient with severe IH shows obliteration of the suprasellar cistern, "sagging" and "fat" midbrain with closed angle between the peduncles/pons , dural enhancement, and tonsillar descent.

Axial T1WI C+ MR in the same patient shows diffuse dural enhancement, hypodense extraaxial fluid collections, and small ventricles with medial deviation of the choroid and internal cerebral veins caused by midbrain descent.

Coronal T1WI C+ MR in the same patient shows subdural fluid with diffuse dural thickening extending into both internal auditory canals . The lateral ventricles are pulled toward the midline.

Coronal T2WI MR shows that the fluid collections are subdural hematomas of different ages. Drainage of the subdural hematomas without recognizing the underlying diagnosis of spontaneous IH caused worsening of the patient's symptoms.

Axial T1WI C+ MR at the C2 level in a patient with spontaneous IH shows the draped curtain appearance of the markedly engorged epidural venous plexus . Brain MR (not shown) showed only mild dural enhancement.

Coronal T1WI C+ MR in the same patient shows an enlarged pituitary gland with mild dural thickening .

Sagittal T1WI MR shows a rounded, "plump" pituitary gland , often seen in IH. Note the effaced suprasellar cistern with optic chiasm draped over the pituitary gland, classic "slumping" midbrain, with decreased angle between the pons and midbrain .

Sagittal T1WI MR shows "sagging" midbrain, tonsillar herniation, and the optic chiasm "draped" over the dorsum sellae. T1WI C+ MR (not shown) demonstrated diffuse dural enhancement in this classic case of spontaneous IH.

Axial T1WI C+ FS MR in a patient with spontaneous IH shows diffuse dura-arachnoid thickening from venous engorgement. Note extension into cerebellopontine angles .

Axial T1WI C+ MR in the same patient after the blood patch shows complete resolution of dura-arachnoid enhancement.

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KEY FACTS

Terminology

Imaging

Top Differential Diagnoses

Clinical Issues

Diagnostic Checklist

TERMINOLOGY

Abbreviations

Definitions

IMAGING

General Features

Best diagnostic clue

Location

Morphology

CT Findings

NECT

CECT

MR Findings

T1WI

T2WI

FLAIR

T2* GRE

T1WI C+

Ultrasonographic Findings

Color Doppler

Angiographic Findings

Nonvascular Interventions

Nuclear Medicine Findings

Imaging Recommendations

Best imaging tool

Protocol advice

DIFFERENTIAL DIAGNOSIS

Meningeal Metastases

Postsurgical Dural Thickening

Idiopathic Hypertrophic Cranial Pachymeningitis

PATHOLOGY

General Features

Etiology

Associated abnormalities

Gross Pathologic & Surgical Features

Microscopic Features

CLINICAL ISSUES

Presentation

Most common signs/symptoms

Clinical profile

Demographics

Age

Natural History & Prognosis

Treatment

DIAGNOSTIC CHECKLIST

Consider

Image Interpretation Pearls

References

Selected References

Cases

Images

Selected Images

Additional Images

43 KiB

Raw Permalink Blame History