Intracranial hypotension syndrome: A radiologist's approach to the "saggy" brain

Transcription

1 Intracranial hypotension syndrome: A radiologist's approach to the "saggy" brain Poster No.: C-1124 Congress: ECR 2017 Type: Educational Exhibit Authors: P. Naval Baudin, J. J. Sánchez Fernández, P. Puyalto de Pablo, D. E. Nova Vaca, M. Huete Naval, J. Valcarcel, C. Majos, C Aguilera Grijalvo ; L'Hospitalet de Llobregat/ES, Barcelona/ES Keywords: Cerebrospinal fluid, Diagnostic procedure, Nuclear medicine conventional, MR, Neuroradiology brain, CNS DOI: /ecr2017/C-1124 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 34

2 Learning objectives Review the pathophysiology of Intracranial Hypotension Syndrome (IHS) and understand its etiology as spontaneous or acquired. Understand the spectrum of imaging findings of the syndrome in the different imaging modalities such as brain and spine CT, MRI and scintigraphy. Discuss the natural history of the disease through MRI findings and how they evolve in response to a number of treatment options. Analyze the possible differential diagnoses and summarize the key points useful to give an accurate diagnosis. Background CONTENTS 1. General aspects: causes and clinical presentation 2. Diagnostic workup 3. Imaging findings 3.1 General imaging aspects 3.2 Brain MRI 3.3 Spine imaging 3.4 Brain CT 4. Treatment and outcome 5. Differential diagnoses 6. Diagnostic pearls 7. Conclusion Page 2 of 34

3 8. References 1. GENERAL ASPECTS: CAUSES AND CLINICAL PRESENTATION The ample diagnostic umbrella of IHS includes multiple processes that cause a theoretical decrease in cerebrospinal fluid (CSF) pressure. IHS may be spontaneous or acquired. Both instances, however have in common a decrease in CSF pressure and/or volume. Known precipitating factors include previous surgery or trauma, lumbar puncture, severe dehydration, and intense exercise [1]. On the other hand, spontaneous IHS is in most cases secondary to a CSF leakage into the epidural space, caused typically by a defects of the dura which may be spontaneous or degenerative. Spontaneous dural defects occur, for example, in the dura adjacent to nerve roots, which is prone to dehiscence and to the formation of arachnoid diverticula. Degenerative disease, represented by disk bulging, osteophytes and other typical signs, may distort the architecture in such a way that it will also produce these leaks [2]. The most common presentation is an intense orthostatic headache, which may be pulsatile or associated with nuchal rigidity in severe cases. Other less common symptoms include nausea, vomiting, CN palsy (namely oculomotor involvement), or radicular symptoms in upper limb. All of them being usually orthostatic in nature. Rarely in very severe cases, more severe, presentations such as parkinsonism, dementia, hypopituitarism, seizures, coma and death have been described [3]. Images for this section: Page 3 of 34

4 Fig. 1: Diagnostic criteria by the "Headache Classification Committee of the International Headache Society (IHS). 2013" [4]. Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 4 of 34

5 Fig. 3: Fig. 3 - The saggy brain. Midline T1WI (a) and edited version (b). Notice the globally descended central brain and brainstem structures, involves a markedly decreased mamillopontine distance (red), with a very acute pontomesencephalic angle (pink), along with a downwardly herniated 3rd ventricle (asterisk). Optic chiasm (orange) is draping over an enlarged hypophysis (green). Descended splenium downwardly curves vein of Galen - internal cerebral veins (blue). Sagging, pons over the clivus, anteriorly flattened, obliterates prepontine cistern (yellow). Slightly descended tonsils through foramen magnum (white line). Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 5 of 34

6 Fig. 2: Cranial MRI signs of the "saggy brain" Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 6 of 34

7 Findings and procedure details 2. DIAGNOSTIC WORKUP The diagnosis of spontaneous intracranial hypotension is made in the clinical context of orthostatic headache, by demonstrating CSF hypotension (either by lumbar puncture, imaging techniques, or by improvement of symptoms after epidural patching), and after excluding other causes that could justify the symptoms, such as dural puncture or other disorders(see table in Fig. 1 on page 28 for diagnostic criteria) [4,5]. Fig. 1: Diagnostic criteria by the "Headache Classification Committee of the International Headache Society (IHS). 2013" [4]. References: Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 7 of 34

8 3. IMAGING FINDINGS 3.1 General imaging aspects Head MRI with and without contrast is the most appropriate test to work up the diagnosis of intracranial hypotension. CT-myelography and Spinal MRI (particularly heavily T2weighted images) are useful in demonstrating the specific foci of CSF leakage. Further studies with intrathecal gadolinium or nuclear medicine myelography may be useful if no leakage is identified with previous studies, having more sensitivity than the former, despite losing anatomical definition [1,2]. Most of the classical imaging findings associated with IHS are secondary to intracranial the redistribution of intracranial fluid components. This redistribution follows the MonroKellie hypothesis, which affirms that in the skull (a rigid cavity) the volumes of its three components (blood, CSF and brain parenchyma) is constant. Parenchymal brain volume is practically stable, therefore, a decrease in CSF volume will result in a proportional increase in intracranial blood volume until a volume-pressure equilibrium is reached. Intracranial venous-structures have a high compliance and quickly adapt to this altered equilibrium, engorging and displacing intracranial structures, conditioning IHS's characteristic imaging presentations. 3.2 Brain MRI Cranial MRI is the best imaging tool for the diagnosis of intracranial hypotension. It presents a series of findings which are characteristic IHS, which may be present with a variable prevalence. Diffuse intense dural enhancement the most frequent finding (85% prevalence) and as such is highly sensitive, though non-specific. Diagnosis of IHS should be based on additional imaging signs, though its absence is useful in suggesting alternative diagnoses [1]. Page 8 of 34

9 Fig. 2: Cranial MRI signs of the "saggy brain" References: Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Brain sagging is a more specific presentation, and englobes a whole subset of anatomic manifestations (see table in Fig. 2 on page 17for summary). These are present in 40-61% of cases [1,6]. Changes include a global descent of central brain structures, along with an anomalous morphology of the pons which may imprint on the clivus (Fig. 3 on page 18). This descent may be objectivized with a diminished mamillopontine distance (<5.5 mm) or a closed pontomesencephalic angle (<50 ) ( Fig. 4 on page 19 ) [7]. Page 9 of 34

10 Fig. 3: Fig. 3 - The saggy brain. Midline T1WI (a) and edited version (b). Notice the globally descended central brain and brainstem structures, involves a markedly decreased mamillopontine distance (red), with a very acute pontomesencephalic angle (pink), along with a downwardly herniated 3rd ventricle (asterisk). Optic chiasm (orange) is draping over an enlarged hypophysis (green). Descended splenium downwardly curves vein of Galen - internal cerebral veins (blue). Sagging, pons over the clivus, anteriorly flattened, obliterates prepontine cistern (yellow). Slightly descended tonsils through foramen magnum (white line). References: Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 10 of 34

11 Fig. 4: Fig. 4 - Angles. Brainstem detail on the previous figure demonstrates a markedly decreased pontomesencephalic angle (PMA) (a) and mammilopontine distance (MPD) (b). PMA may be considered pathologic when < 50, whilst normal when > 65. Normal MPD is above 5.5 mm. References: Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Distended veins and dural sinuses (present in around 75% of cases), marked thickening and enhancement of pachymeninges, and subdural fluid collection (hygromas or chronic subdural hematomas) ( Fig. 5 on page 20, Fig. 6 on page 21 ) compensating a small ventricular system ( Fig. 7 on page 22 ), all responding to the already explained Monro-Kellie hypothesis [8]. Page 11 of 34

12 Fig. 5: Fig. 5 - Dural enhancement and fluid collections. Contrast-enhanced T1WI (a) and T2WI (b). Diffuse pachymeningeal thickening and enhancement (arrows). Extraaxial fluid collections, isointense to CSF (hygromas) in T1 and T2 (arrowheads). Downwardly transtentorially herniated tempral uncus bilaterally (dashed arrows). References: Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Sagittal T1WI images are very useful in identifying the distorted "sagging" anatomy, whilst contrast-enhanced T1WI are useful in demonstrating diffuse dural enhancement. 3.3 Spine Imaging CT-myelography is the most frequently used method for identifying CSF leaks. It is performed by introducing iodinated contrast-material into the thecal sac. The method is fast, highly accessible and offers high resolution and image quality. It may render specific foci of CSF leak to the epidural space, and is also useful in identifying foci of dural weakness, for example arachnoid diverticuli [2]. Spinal MRI also renders high-quality images that may give similar results than CTmyelography. Highly T2-weighted images with fat-suppression, to eliminate signal from the epidural fat, are the most useful [2]. Page 12 of 34

13 Radionuclide cisternography is performed administering intrathecal 111-Indiethylene triamine pentaacetic acid (DTPA), and acquiring images immediately, 1, 2, 4 and 24 hours after radionuclide administration. It gives both direct visual signs of CSF leakage with a relatively high sensitivity ( Fig. 8 on page 23 ). However, despite all these techniques, in about 45-55% of cases, no leakage will be identified [2]. Fig. 8: Fig y.o. woman with intense occipital headache, which worsens in upright position and quickly improves in decubitus. (a) Sagittal T1 image demonstrates a saggy midbrain, closed midbrain-pons angle, diminished mamillopontine distance (arrowhead), marked impromting of pons on clivus (cross), and downward tonsillar displacement (curved arrow) in a patient with typical symptoms suggesting intracranial hypotension. (b) Scintigraphy 4-hours post intrathecal radionuclide administration demonstrates extrathecal activity lateral to the the level of the cervical and dorsal Page 13 of 34

14 vertebrae (arrows) suggesting cerebrospinal fluid leakage in these locations. (c) 1 month later follow-up after symptom resolution shows improvement of imaging findings (namely less herniated amydala and less impromted pons). References: Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES 3.4 Brain CT Brain CT is nonspecific and rarely useful for the diagnosis of HIS, nevertheless, several abnormalities may be observed, namely obliteration of the basilar cisterns due to brain sagging, along with crowding of the foramen magnum due to tonsillar herniation. 4. TREATMENT AND OUTCOME Patients with uncomplicated IHS with mild to moderate symptoms may be treated conservatively, with strict bed rest, and avoidance of upright position. Radiologic signs will improve progressively responding to recovery of CSF pressure/volume equilibrium ( Fig. 9 on page 24 ). In longstanding or severe cases, mainstay treatment is epidural blood patching. Further treatment options include continuous epidural saline infusion, epidural fibrin glue, or surgical repair of the defect [9,10]. Page 14 of 34

15 Fig. 9: Fig. 9 - Sagittal FLAIR image (a) demonstrates an enlarged pituitary gland with the optic chiasm draped over the sella (arrow), dural engorgement in the surface of the clivus (arrowhead), and caudal displacement of the tonsils of the cerebellum (curved arrow) in a patient with typical symptoms suggesting intracranial hypotension. The patient is treated with corticoids and one month later symptoms resolve as well as the imaging findings (b), the pituitary decreases in size (arrow), the dura in thickness (arrowhead) and the tonsils go back to a more cranial position (curved arrow). References: Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES 5. DIFFERENTIAL DIAGNOSES The main differential diagnoses mainly include other causes of meningeal thickening and enhancement. Meningitis, may simulate many of the signs of IHS, nevertheless, enhancement tends to be more pial and not dural. Nonetheless, dural enhancement in primordially pachymeningeal meningitis may be difficult to differentiate from that of IHS ( Fig. Page 15 of 34

16 10 on page 25 ). Extraaxial pyogenic abscesses, however may usually easily be differentiated from IHS subdural collection based on the former's marked homogenous diffusion restriction ( Fig. 11 on page 26 ). Meningeal metastases may also affect the dura, though the associated thickening is usually more severe and focal, with an irregular and bumpy pattern. Dural sinus thrombosis may simulate venous engorgement, this may be excluded demonstrating venous permeability ( Fig. 12 on page 27 ). Fig. 10: Fig y.o. woman with proven Staphylococcus aureus meningitis. Contrast-enhanced T1WI on cranial axial (a and b) and cervicodorsal sagittal (c) levels demonstrate marked diffuse dural enhancement (arrowheads). 3D MRI-venography Page 16 of 34

17 shows thrombosis of left transverse sinus (d) (arrow). These findings may easily be mistaken for dural enhancement related to IHS. References: Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Fig. 11: Fig Subdural pyogenic abscess. Non-enhanced CT (a) shows a laminar hypodense rim on the occipital falx cerebrii's right margin and a similar image on the frontal falx (arrowheads). MRI shows on T2WI (b) high signal, on contrast-enhanced T1WI (c) low signal with an intensely enhancing rim, and DWI (d) shows marked, homogenous restriction, confirmed on ADC map (not shown). References: Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Images for this section: Page 17 of 34

18 Fig. 2: Cranial MRI signs of the "saggy brain" Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 18 of 34

19 Fig. 3: Fig. 3 - The saggy brain. Midline T1WI (a) and edited version (b). Notice the globally descended central brain and brainstem structures, involves a markedly decreased mamillopontine distance (red), with a very acute pontomesencephalic angle (pink), along with a downwardly herniated 3rd ventricle (asterisk). Optic chiasm (orange) is draping over an enlarged hypophysis (green). Descended splenium downwardly curves vein of Galen - internal cerebral veins (blue). Sagging, pons over the clivus, anteriorly flattened, obliterates prepontine cistern (yellow). Slightly descended tonsils through foramen magnum (white line). Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 19 of 34

20 Fig. 4: Fig. 4 - Angles. Brainstem detail on the previous figure demonstrates a markedly decreased pontomesencephalic angle (PMA) (a) and mammilopontine distance (MPD) (b). PMA may be considered pathologic when < 50, whilst normal when > 65. Normal MPD is above 5.5 mm. Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 20 of 34

21 Fig. 5: Fig. 5 - Dural enhancement and fluid collections. Contrast-enhanced T1WI (a) and T2WI (b). Diffuse pachymeningeal thickening and enhancement (arrows). Extraaxial fluid collections, isointense to CSF (hygromas) in T1 and T2 (arrowheads). Downwardly transtentorially herniated tempral uncus bilaterally (dashed arrows). Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 21 of 34

22 Fig. 6: Fig. 6 - Dural and venous engorgement. T1 contrast enhanced image shows most of the signs of intracranial hypotension. Global dural engorgement (arrows), dropping of the splenium of corpus callosum depressing the junction between the internal cerebral vein and the vein of Galen (thick arrow), "Saggy" midbrain with the fat pons sign (asterisk), and closed midbrain - pons angle with diminished mamillopontine distance (arrowhead). Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 22 of 34

23 Fig. 7: Fig. 7 - Axial post-gadolinium T1-weighted images shows a slit like 3rd ventricle (arrowhead), and diffuse, enhancing dural thickening (arrows). Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 23 of 34

24 Fig. 8: Fig y.o. woman with intense occipital headache, which worsens in upright position and quickly improves in decubitus. (a) Sagittal T1 image demonstrates a saggy midbrain, closed midbrain-pons angle, diminished mamillopontine distance (arrowhead), marked impromting of pons on clivus (cross), and downward tonsillar displacement (curved arrow) in a patient with typical symptoms suggesting intracranial hypotension. (b) Scintigraphy 4-hours post intrathecal radionuclide administration demonstrates extrathecal activity lateral to the the level of the cervical and dorsal vertebrae (arrows) suggesting cerebrospinal fluid leakage in these locations. (c) 1 month later follow-up after symptom resolution shows improvement of imaging findings (namely less herniated amydala and less impromted pons). Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 24 of 34

25 Fig. 9: Fig. 9 - Sagittal FLAIR image (a) demonstrates an enlarged pituitary gland with the optic chiasm draped over the sella (arrow), dural engorgement in the surface of the clivus (arrowhead), and caudal displacement of the tonsils of the cerebellum (curved arrow) in a patient with typical symptoms suggesting intracranial hypotension. The patient is treated with corticoids and one month later symptoms resolve as well as the imaging findings (b), the pituitary decreases in size (arrow), the dura in thickness (arrowhead) and the tonsils go back to a more cranial position (curved arrow). Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 25 of 34

26 Fig. 10: Fig y.o. woman with proven Staphylococcus aureus meningitis. Contrast-enhanced T1WI on cranial axial (a and b) and cervicodorsal sagittal (c) levels demonstrate marked diffuse dural enhancement (arrowheads). 3D MRI-venography shows thrombosis of left transverse sinus (d) (arrow). These findings may easily be mistaken for dural enhancement related to IHS. Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 26 of 34

27 Fig. 11: Fig Subdural pyogenic abscess. Non-enhanced CT (a) shows a laminar hypodense rim on the occipital falx cerebrii's right margin and a similar image on the frontal falx (arrowheads). MRI shows on T2WI (b) high signal, on contrast-enhanced T1WI (c) low signal with an intensely enhancing rim, and DWI (d) shows marked, homogenous restriction, confirmed on ADC map (not shown). Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 27 of 34

28 Fig. 12: Fig Superior Sagittal sinus (SSS) thrombosis. Sagittal (a) and axial (b) T1WI show abscence of flow-void in SSS (arrowheads), whilst it is preserved in straight sinus (arrows). Note that the signal intensity of the thrombus may change over time, following degraded hematic content signal. 3D MRI-venography lateral (c) and anteroposterior (d) views demonstrate lack of signal in the SSS. Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 28 of 34

29 Fig. 1: Diagnostic criteria by the "Headache Classification Committee of the International Headache Society (IHS). 2013" [4]. Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 29 of 34

30 Conclusion 6. DIAGNOSTIC PEARLS TO TAKE HOME Ultimate cause is low CSF volume/pressure, usually associated to CSF leakage which may be spontaneous or secondary Clinical presentation: Intense orthostatic headache Diagnosis is based on clinical presentation and proof of low CSF pressure (be it by lumbar puncture or imaging techniques) Cranial MRI best diagnostic tool. Typical imaging signs: "Sagging" descended central brain and brainstem, amygdala herniation, distended veins, diffuse pachymeningeal enhancement, and large hypophysis Sagittal midline T1 best demonstrates brain sagging. Contrast enhanced images useful for dural enhancement and venous engorgement Spine imaging (CT-myelography, Spinal MRI or scintigraphy) may be useful in demonstrating the source of leakage, if necessary 7. CONCLUSION Intracranial hypotension syndrome, be it primary or secondary to one of many causes; may present with a wide spectrum of imaging findings. This presentation may be florid with indistinguisable radiologic signs, which should not be missed; or subtle with nonspecific alterations, in which case careful study the demographic and clinical context might give the key to the diagnosis. Images for this section: Page 30 of 34

31 Fig. 3: Fig. 3 - The saggy brain. Midline T1WI (a) and edited version (b). Notice the globally descended central brain and brainstem structures, involves a markedly decreased mamillopontine distance (red), with a very acute pontomesencephalic angle (pink), along with a downwardly herniated 3rd ventricle (asterisk). Optic chiasm (orange) is draping over an enlarged hypophysis (green). Descended splenium downwardly curves vein of Galen - internal cerebral veins (blue). Sagging, pons over the clivus, anteriorly flattened, obliterates prepontine cistern (yellow). Slightly descended tonsils through foramen magnum (white line). Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 31 of 34

32 Fig. 2: Cranial MRI signs of the "saggy brain" Hospital Universitari de Bellvitge - L'Hospitalet de Llobregat/ES Page 32 of 34

33 Personal information P.N.B.; D.E.N.V.; M.H.N.; and J.V.J. from the Department of Radiology, Hospital Universitari de Bellvitge, L'Hospitalet de Llobregat, Barcelona, Spain. J.J.S.F.; C.M.; and C.A.G. from the Department of Radiology, Institut de Diagnòstic per la Imatge-IDI, Hospital Universitari de Bellvitge, L'Hospitalet de Llobregat, Barcelona, Spain. P.P.dP. from the Department of Radiology, Hospital Universitari Germans Trias i Pujol, Badalona, Barcelona, Spain. References 8. REFERENCES [1] Kranz PG, Tanpitukpongse TP, Choudhury KR, Amrhein TJ, Gray L. Imaging Signs in Spontaneous Intracranial Hypotension: Prevalence and Relationship to CSF Pressure. AJNR Am J Neuroradiol 2016;37: [2] Kranz PG, Luetmer PH, Diehn FE, Amrhein TJ, Tanpitukpongse TP, Gray L. Myelographic Techniques for the Detection of Spinal CSF Leaks in Spontaneous Intracranial Hypotension. AJR Am J Roentgenol 2016;206:8-19. [3] Paldino M, Mogilner AY, Tenner MS. Intracranial hypotension syndrome: a comprehensive review. Neurosurg Focus 2003;15:ECP2. [4] Headache Classification Committee of the International Headache Society (IHS). The International Classification of Headache Disorders, 3rd edition (beta version). Cephalalgia 2013;33: [5] Schievink WI, Dodick DW, Mokri B, Silberstein S, Bousser M-G, Goadsby PJ. Diagnostic criteria for headache due to spontaneous intracranial hypotension: a perspective. Headache 2011;51: Page 33 of 34

34 [6] Shankar JJS, Chakraborty S, Lum C. The venous hinge--an objective sign for the diagnosis and follow-up of treatment in patients with intracranial hypotension syndrome. Neuroradiology 2009;51: [7] Shah LM, McLean LA, Heilbrun ME, Salzman KL. Intracranial hypotension: Improved MRI detection with diagnostic intracranial angles. Am J Roentgenol 2013;200: [8] Farb RI, Forghani R, Lee SK, Mikulis DJ, Agid R. The venous distension sign: a diagnostic sign of intracranial hypotension at MR imaging of the brain. AJNR Am J Neuroradiol 2007;28: [9] Mokri B. Spontaneous low pressure, low csf volume headaches: Spontaneous CSF leaks. Headache 2013;53: [10] Hoffmann J, Goadsby PJ. Update on intracranial hypertension and hypotension. Curr Opin Neurol 2013;26: Page 34 of 34