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Meninges of the Brain and Spine

Meninges of the Brain and Spine

08.02.21

Outline of the Ø of the meninges and Spine Ø Enhancement Ø Techniques Ø Pathology of meninges Majda M Thurnher Medical University of Vienna | University Hospital Vienna Department of Biomedical Imaging and Image-Guided Therapy Vienna | Austria

CEO of the European Board of Neuroradiology (EBNR) Past President of the European Society of Neuroradiology (ESNR)

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THE MENINGES THE DURA MATTER „ the hard mother“ • Membranous coverings of the • thick, dense, fibrous and INELASTIC membrane brain and spinal • composed of two layers: cord a) the periosteal layer that lies closest to the calvarium • Three layers: dura b) the meningeal layer that lies closest to the brain mater, arachnoid tissue mater, • Mostly fused (except for the dural sinuses) • Two major functions: - Provide a supportive framework for the cerebral and cranial vasculature - Act with to protect the CNS from mechanical damage

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THE DURA MATTER THE DURAL INFOLDINGS (processes) „ the hard mother“

• The receives its own vasculature; primarily from the middle meningeal and vein TENTORIUM CEREBELLI • It is innervated by the trigeminal (V1, V2 and V3) • Lacks the blood-brain barrier (BBB) • In some areas within the , the meningeal layer of the dura mater folds inwards as DURAL REFLECTIONS. They partition the brain, and divide the into several compartments. Dural reflections refer to places where two face-to-face meningeal layers descend into the cranial cavity to form the septa that compartmentalize the brain.

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FALX CEREBRI

• The largest infolding

• in the longitudinal cerebral fissure, which divides the two hemispheres of the

• relatively thin anteriorly where it attaches to the

• broader posteriorly where it attaches to the superior surface of the tentorium cerebelli inferiorly

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DIAPHRAGMA SELLAE TENTORIUM CEREBELLI • Small circular fold of dura mater that forms the roof for the • A small opening in its center allows passage of the stalk of the pituitary gland

• The “U” shaped tentorium cerebelli runs transversely between the and occipital lobes.

• There is an opening in the falx cerebri, known as the tentorial incisura (sometimes referred to as the tentorial notch), that allows the to pass through into the middle cranial fossa.

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DURAL VENOUS SINUSES THE ARACHNOID MATTER • Venous channels located intracranially between the two layers of dura „ the spidery mother“ matter • the middle layer of the meninges, lying directly underneath the dura mater

• It consists of layers of

• Thin, lucent membrane

• avascular • does not receive any innervation

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THE SUB-ARACHNOID SPACE

• Underneath the arachnoid is a space known as the sub-arachnoid space • It contains cerebrospinal fluid

• Small projections of into the dura (ARACHNOID GRANULATIONS) allow CSF to re-enter the circulation via the

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Arachnoid granulations (Pacchionian granulation)

• They most frequently occur in a parasagittal location with the sinus transversus and superior sagittal sinus being the most common locations.

• incidental osteolytic, sharply circumscribed indolent-appearing • On MRI a filling defect in dural venous lucencies on skull CT sinuses, which can be mistaken for SVT

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THE PIA MATER „ the delicate mother“

• located underneath the sub-arachnoid space

• It is very thin and tightly adhered to the surface of the brain and , it is the only covering to follow the contours of the brain (the gyri and fissures)

• It is highly vascularized, with blood vessels perforating through the membrane to supply the underlying neural tissue

• Two layers: a) epipial layer – connects to the arachnoid matter b) intima pia – connects to the neural tissue Leptomeninges = arachnoid + pia

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THE PERIVASCULAR SPACES SPINAL MENINGES

• Three layers of meninges envelop the spinal cord and the roots of spinal

Dura mater

Arachnoid

Pia mater

• the pia mater forms sheaths around the blood vessels that enter and exit the brain perpendicular to the meninges, specifically from the subarachnoid space Leptomeninges to within the brain parenchyma

• This sheathing creates an interstitial fluid-filled space, known as the perivascular or Virchow-Robin space, between the vessel walls and the pia

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THE SPINAL DURA MATER

• Around the margin of the cranial dura mater is closely adherent to the bone, and is continuous with the spinal dura mater

• The Spinal Dura Mater (dura mater spinalis) forms a loose sheath around the medulla spinalis

• represents only the meningeal layer of the cranial dura mater (the endosteal layer ceases at the foramen magnum)

• its place is taken by the lining the vertebral canal

Spinal dura mater is thicker and less vascular than cranial dura mater

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SPINAL SPACES

EPIDURAL SPACE: between dura and periosteum • Fat • Internal vertebral venous plexus • roots below S2

SUBDURAL SPACE between arachnoid and pia • • CSF • • Veins

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Internal vertebral venous plexus

• It sits within the within a layer of fat containing the internal vertebral venous plexus. • The vertebral venous plexus is a highly anastomotic network of valveless veins running along the entire length of the spinal canal.

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Subdural

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Embryology of the meninges BLOOD SUPPLY Dura: • The major arteries that supply the dura are derived from the internal carotid, • The dura mater is derived from the mesoderm, vertebral, maxillary, ascending pharyngeal, lacrimal, occipital, and ethmoidal • The arachnoid and pia mater are derived from the arteries. ectoderm • Of the arteries that supply the dura, the (MMA), which branches from the ’s maxillary branch, is the most important • Specifically, the development of the meninges begins with what is known as the perimedullarly mesenchyme, which contains cells from both the ectoderm and mesoderm Arachnoid: avascular

• The leptomeninges forms first, as cells from the neural crest differentiate into the pia and arachnoid Pia: highly vascularized, small cappilaries

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SPACES

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Normal dural enhancement Outline

Ø Anatomy of the meninges

Ø Enhancement Ø Techniques

Ø Pathology of meninges • On T1-weighted MR images: normal dura mater and inner table bone are uniformly hypointense • After contrast normal dura shows thin, linear, and discontinuos enhancement (variable thickness)

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Pachymeningeal enhancement pattern Enhancement pattern Dura-arachnoid enhancement

a) Pachymeningeal enhancement pattern Dura-arachnoid enhancement

b) Pia-subarachnoid enhancement pattern Leptomeningeal enhancement

Dural and outer layer of arachnoid pattern of enhancement!

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Pia-subarachnoid enhancement pattern Enhancement pattern Leptomeningeal enhancement Pachymeningeal Pia-subarachnoid enhancement enhancement Dura-arachnoid enhancement Leptomeningeal enhancement

Intracranial hypotension (bacterial, viral, fungal) Transient postoperative changes Carcinomatous meningitis Granulomatous disease Enhancement of sulci and subarachnoid spaces Metastatic disease Follows the pial surface of the brain and fills the subarachnoid spaces of the Lymphoma sulci and cisterns

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Pachymeningeal enhancement Intracranial hypotension Dura-arachnoid enhancement

Hypotension Meningioma Metastatic disease

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Pia-subarachnoid enhancement Leptomeningeal enhancement Enhancement pattern

Pachymeningeal Pia-subarachnoid enhancement enhancement Dura-arachnoid enhancement Leptomeningeal enhancement

Thin, linear enhancement Thick, lumpy, nodular

Tuberculous meningitis

Meningitis (bacterial, viral, fungal) Carcinomatous meningitis

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Meningitis

Pia-subarachnoid enhancement Pia-subarachnoid enhancement Thin, linear Thick, nodular

Tuberculous meningitis Metastatic disease

Metastatic disease

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Enhancement pattern

Meningitis

Pachymeningeal enhancement Pia-subarachnoid enhancement

Thin, linear enhancement Thick, lumpy, nodular

bilateral, diffuse unilateral Carcinomatous meningitis

Meningitis IgG-related pachymeningitis (bacterial, viral, fungal) Sturge-Weber syndrome Neurosarcoidosis Vasculitis Vasculitis Sarcoidosis IgG- related pachymeningitis

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CE-FLAIR Outline

Ø Anatomy of the meninges

Ø Enhancement Ø Techniques

Ø Pathology of meninges

CE-T1WI

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CE-FLAIR

CE-T1WI CE-FLAIR CE-T1WI

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CE-T1WI CE-FLAIR

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Outline

Ø Anatomy of the meninges Ø Enhancement Ø Techniques

Ø Pathology of meninges

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Meningitis Meningitis Imaging Findings Inflammatory infiltration of PIA, ARACHNOID, and CSF • Acute pyogenic (bacterial) • High FLAIR signal of CSF spaces • Lymphocytic (viral) • Dural/meningeal enhancement • Chronic (TB or granulomatous) • • Subdural effusions/empyema • Venous & arterial infarcts • DWI high signal in VR Spaces

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• High FLAIR signal of CSF spaces

Congestion and hyperemia of the leptomeninges with exudates in the subarachnoid space (high protein content in subarachnoid spaces)

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• Infarcts

• Subdural effusions

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• Debris level

• Leptomeningeal enhancement

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Inflammation

• DWI: high signal in subarachnoid spaces

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IgG4-related pachymeningitis Ig G4-related pachymeningitis

• Rare manifestation of IgG4 related fibroinflammatory • Inflammation leading to a localized or diffuse disease spectrum thickening of the meninges overlying the supratentorial hemispheres, skull base, or spinal cord • Autoimmune pancreatitis Mikulicz disease • Symptoms related to mass effect or focal deficits Pseudotumor of the lung IgG4-related disease caused by the compression of blood vessels or Tubulointerstitial nephritis (IgG4-RD) nerves Riedel thyroiditis • CT: Bone involvement • CNS involvement is rare, most common CNS manifestation • MRI: Linear/ mass forming, T2: relatively hipointens, is hypophysitis T1+ Gd: contrast enhancement

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Boban J, Ardali S, Thurnher M. Neuroradiology 2018 69 70

Courtesy of Andrea Rossi/IT Anti-GQ1b antibody syndrome

1. Bickerstaff Brain Stem (BBE) Miller-Fisher Syndrome 2. Miller-Fisher Syndrome (GBS Variant) 3. Acute Ophtalmoparesis

• inflammatory non-infectious origin and specifically to be an autoimmune disease

th • immune cross-reaction seems to be triggered by previous 6 nerve exposure to Campylobacter Jejuni and Mycoplasma pneumoniae

7th nerve 3rd nerve • Different CNS phenotypes 5th nerve

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Sarcoidosis

• Granulomatous disease • Unknown etiology • Young adults

Neurosarcoid (in 5%) • Solitary or multifocal CNS masses • Dural (30-50%), meningeal (30%) • Optic chiasm, hypothalamus, infundibulum • • Spine

Abnormal Chest x-ray in 90% Courtesy P Sundgren / SE 73 74

Vasculitis

Neoplastic

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Metastatic disease

Meningeal Sarcoma

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Metastatic disease Differential

Infection Infection Inflammatory drug toxicity

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Metastatic disease Lymphoma

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Thank you

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