When in sphenoid bone and T-bone → AbAG (arachnoid pit)
Definitions
Arachnoid villi: Term used to describe smaller AG
AG: Enlarged arachnoid villi projecting from subarachnoid space (SAS) into major dural venous sinus (DVS) lumen
AbAG: AG that penetrates dura but fails to reach DVS, typically in sphenoid or temporal bone
Rarely other bones like parietal, occipital bone
Also referred to as arachnoid pits or osteodural defects
IMAGING
General Features
CT Findings
MR Findings
Imaging Recommendations
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
Gross Pathologic & Surgical Features
Microscopic Features
CLINICAL ISSUES
Presentation
Demographics
Natural History & Prognosis
Treatment
DIAGNOSTIC CHECKLIST
Consider
Image Interpretation Pearls
Selected References
Freeman CW et al: Variations of the CNS venous system mimicking pathology: spectrum of imaging findings. J Neuroimaging. ePub, 2019
Sade R et al: Brain herniation into the transverse sinuses' arachnoid granulations in the pediatric population investigated with 3 T MRI. Acta Neurol Belg. 119(2):225-31, 2019
Taieb G et al: Reversible giant arachnoid granulations. Neurology. 91(24):1107-8, 2018
Battal B et al: Brain herniations into the dural venous sinuses or calvarium: MRI of a recently recognized entity. Neuroradiol J. 27(1):55-62, 2014
De Keyzer B et al: Giant arachnoid granulations mimicking pathology. A report of three cases. Neuroradiol J. 27(3):316-21, 2014
Settecase F et al: Spontaneous lateral sphenoid cephaloceles: anatomic factors contributing to pathogenesis and proposed classification. AJNR Am J Neuroradiol. 35(4):784-9, 2014
Alonso RC et al: Spontaneous skull base meningoencephaloceles and cerebrospinal fluid fistulas. Radiographics. 33(2):553-70, 2013
Barañano CF et al: Sternberg's canal: fact or fiction? Am J Rhinol Allergy. 23(2):167-71, 2009
La Fata V et al: CSF leaks: correlation of high-resolution CT and multiplanar reformations with intraoperative endoscopic findings. AJNR Am J Neuroradiol. 29(3):536-41, 2008
Lloyd KM et al: Imaging of skull base cerebrospinal fluid leaks in adults. Radiology. 248(3):725-36, 2008
Schuknecht B et al: Nontraumatic skull base defects with spontaneous CSF rhinorrhea and arachnoid herniation: imaging findings and correlation with endoscopic sinus surgery in 27 patients. AJNR Am J Neuroradiol. 29(3):542-9, 2008
Haroun AA et al: Arachnoid granulations in the cerebral dural sinuses as demonstrated by contrast-enhanced 3D magnetic resonance venography. Surg Radiol Anat. 29(4):323-8, 2007
Amlashi SF et al: Intracranial hypertension and giant arachnoid granulations. J Neurol Neurosurg Psychiatry. 75(1):172, 2004
Liang L et al: Normal structures in the intracranial dural sinuses: delineation with 3D contrast-enhanced magnetization prepared rapid acquisition gradient-echo imaging sequence. AJNR Am J Neuroradiol. 23(10):1739-46, 2002
Casey SO et al: Prevalence of arachnoid granulations as detected with CT venography of the dural sinuses. AJNR Am J Neuroradiol. 18(5):993-4, 1997
Leach JL et al: Normal appearance of arachnoid granulations on contrast-enhanced CT and MR of the brain: differentiation from dural sinus disease. AJNR Am J Neuroradiol. 17(8):1523-32, 1996
Roche J et al: Arachnoid granulations in the transverse and sigmoid sinuses: CT, MR, and MR angiographic appearance of a normal anatomic variation. AJNR Am J Neuroradiol. 17(4):677-83, 1996
Related Anatomy
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Related Differential Diagnoses
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References
Tables
Tables
KEY FACTS
Terminology
Imaging
Top Differential Diagnoses
Pathology
Clinical Issues
Diagnostic Checklist
TERMINOLOGY
Abbreviations
Arachnoid granulation (AG)
Aberrant arachnoid granulation (AbAG)
Synonyms
Pacchionian depressions, granulations, or bodies
When large → "giant" AG
When in sphenoid bone and T-bone → AbAG (arachnoid pit)
Definitions
Arachnoid villi: Term used to describe smaller AG
AG: Enlarged arachnoid villi projecting from subarachnoid space (SAS) into major dural venous sinus (DVS) lumen
AbAG: AG that penetrates dura but fails to reach DVS, typically in sphenoid or temporal bone
Rarely other bones like parietal, occipital bone
Also referred to as arachnoid pits or osteodural defects
IMAGING
General Features
CT Findings
MR Findings
Imaging Recommendations
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
Gross Pathologic & Surgical Features
Microscopic Features
CLINICAL ISSUES
Presentation
Demographics
Natural History & Prognosis
Treatment
DIAGNOSTIC CHECKLIST
Consider
Image Interpretation Pearls
Selected References
Freeman CW et al: Variations of the CNS venous system mimicking pathology: spectrum of imaging findings. J Neuroimaging. ePub, 2019
Sade R et al: Brain herniation into the transverse sinuses' arachnoid granulations in the pediatric population investigated with 3 T MRI. Acta Neurol Belg. 119(2):225-31, 2019
Taieb G et al: Reversible giant arachnoid granulations. Neurology. 91(24):1107-8, 2018
Battal B et al: Brain herniations into the dural venous sinuses or calvarium: MRI of a recently recognized entity. Neuroradiol J. 27(1):55-62, 2014
De Keyzer B et al: Giant arachnoid granulations mimicking pathology. A report of three cases. Neuroradiol J. 27(3):316-21, 2014
Settecase F et al: Spontaneous lateral sphenoid cephaloceles: anatomic factors contributing to pathogenesis and proposed classification. AJNR Am J Neuroradiol. 35(4):784-9, 2014
Alonso RC et al: Spontaneous skull base meningoencephaloceles and cerebrospinal fluid fistulas. Radiographics. 33(2):553-70, 2013
Barañano CF et al: Sternberg's canal: fact or fiction? Am J Rhinol Allergy. 23(2):167-71, 2009
La Fata V et al: CSF leaks: correlation of high-resolution CT and multiplanar reformations with intraoperative endoscopic findings. AJNR Am J Neuroradiol. 29(3):536-41, 2008
Lloyd KM et al: Imaging of skull base cerebrospinal fluid leaks in adults. Radiology. 248(3):725-36, 2008
Schuknecht B et al: Nontraumatic skull base defects with spontaneous CSF rhinorrhea and arachnoid herniation: imaging findings and correlation with endoscopic sinus surgery in 27 patients. AJNR Am J Neuroradiol. 29(3):542-9, 2008
Haroun AA et al: Arachnoid granulations in the cerebral dural sinuses as demonstrated by contrast-enhanced 3D magnetic resonance venography. Surg Radiol Anat. 29(4):323-8, 2007
Amlashi SF et al: Intracranial hypertension and giant arachnoid granulations. J Neurol Neurosurg Psychiatry. 75(1):172, 2004
Liang L et al: Normal structures in the intracranial dural sinuses: delineation with 3D contrast-enhanced magnetization prepared rapid acquisition gradient-echo imaging sequence. AJNR Am J Neuroradiol. 23(10):1739-46, 2002
Casey SO et al: Prevalence of arachnoid granulations as detected with CT venography of the dural sinuses. AJNR Am J Neuroradiol. 18(5):993-4, 1997
Leach JL et al: Normal appearance of arachnoid granulations on contrast-enhanced CT and MR of the brain: differentiation from dural sinus disease. AJNR Am J Neuroradiol. 17(8):1523-32, 1996
Roche J et al: Arachnoid granulations in the transverse and sigmoid sinuses: CT, MR, and MR angiographic appearance of a normal anatomic variation. AJNR Am J Neuroradiol. 17(4):677-83, 1996
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