John H. Woo, MD Associate Professor, Department of Radiology Perelman School of Medicine, University of Pennsylvania Medical Center October 28, 2016
Cerebrospinal fluid (CSF) Bulk model (traditional) Production: 500 ml/day 150 ml total volume Choroid plexus Arachnoid villi Multicompartmental model Blood Interstitial fluid Virchow-Robin spaces CSF (Cervical) lymphatics CSF pulsations Absorbers Compliance? Brinker T, Stopa E, Morrison J, Klinge P, A new look at cerebrospinal fluid circulation, Fluids and Barriers of the CNS (2014) 11:10.
Hydrocephalus Obstructive v communicating Look for transition point of obstruction! Congenital v acquired Idiopathic v secondary Meningitis, subarachnoid hemorrhage, carcinomatosis inph Acute v chronic Ex vacuo = atrophy/encephalomalacia
Hydrocephalus - presentation Acute Headache Lethargy/malaise Nausea/vomiting Papilledema Rapid head enlargement (children) Chronic Progressive gait dysfunction magnetic, shuffling Dementia Frontal, subcortical Urinary incontinence Detrusor overactivity UMN signs May be asymptomatic
Obstructive hydrocephalus Acute Early: temporal horn III convexity, floor Periventricular changes Chronic Ventricular > sulcal enlargement Thin, elevated callosum Expanded III recesses
Normal Pressure Hydrocephalus Described by Adams/Hakim NEJM (1965) 273:117-126. Triad: gait disturbance, dementia, incontinence Ventriculomegaly without elevated ICP Secondary vs. idiopathic (inph) Many subsequent articles do not distinguish inph: Unknown etiology and mechanism inph Guidelines published probable/possible/unlikely Neurosurgery 2005 57(3):4-16.
inph clinical aspects Elderly (> 60 yo) >40 in 2005 guidelines Gait (balance), cognition, urinary continence Gait tends to be earliest, responds best to shunting Tap test (TT) - popular >30 ml do symptoms improve? External Lumbar Drainage (ELD) CSF infusion tests: measure Rout (resistance to CSF outflow)
Ventriculomegaly: Can radiologists distinguish NPH from atrophy? Each of NPH triad can be caused by many pathologies in the elderly Ataxia: Parkinson s, spinal stenosis, arthritis, neuropathy, Dementia: CVA, Alzheimer s, neurodegenerative disease, Incontinence: urologic disease, (potentially) treatable cause of neurologic deficit However, shunting is not benign Early series (1992, 127 pts): 36% improvement/28% complications Vanneste et al, Neurology (1992) 42:54-59. Appealing idea: can imaging distinguish/predict shunt response?
Ventriculomegaly: Should radiologists distinguish NPH from atrophy? NPH is a clinical diagnosis, informed by imaging Atrophy also causes ventriculomegaly NPH and Alzheimer s Disease can co-exist make or refute the diagnosis without full clinical data? Ideal world: knowledgeable clinician takes imaging into account, makes/refutes diagnosis. Real world:??
Evans ratio or index A = transverse measure across frontal horns (yellow) B = max intracranial biparietal diameter, same slice (red) Evans Ratio = A/B (0.44 in example to the right) NPH guidelines: EI > 0.3. (EI > 0.33 more specific)
White matter signal Periventricular signal Supportive feature in 2005 guidelines However, not essential Not a criterion in Japanese trials Ischemic disease: negative predictor? Conflicting studies 2-hit hypothesis? (Bradley, et al, JMRI 2006 24(4): 747-755) Confounds: common in elderly difficult to distinguish
Callosal angle Coronal plane perpendicular to AC-PC line, @PC Acute (< 90 ) = NPH. Obtuse (> 90 ) = atrophy Ishii K et al, Eur Radiol (2008) 18:2678-2683
Focally dilated sulci Initially described in 1998 Kitagaki et al (1998) AJNR 19:1277. Holodny et al (1998) J Neurosurg 89(5): 742-747. Sylvian fissures and basal cisterns may also dilate
DESH pattern Disproportionately Enlarged Subarachnoid-Space Hydrocephalus Ventriculomegaly Tight high convexity/medial sulci Many have enlarged Sylvian fissures
Developing DESH? Or risk of developing NPH? 4 years later
SINPHONI trial (2010) Multicenter trial in Japan, 100 patients Inclusion criteria: >60 yo, normal CSF, idiopathic Any component of triad DESH pattern Results: 12-m improvement 69 77% Confirms diagnostic value of DESH specific to inph? Hashimoto M et al, Cerebrospinal Fluid Research 2010 7:18
SINPHONI-2 trial (2015) Multicenter trial, n=93, lumboperitoneal shunt Same inclusion criteria as SINPHONI 49 randomized to immediate shunt; 44 waited 3 mo Results: 63% improvement @ 12 mo @ 3 mo: 65% in group 1; 2% in group 2 (p<0.0001) Adverse events (22%): shunt malfunction/overdrainage Post hoc analysis: TT predictive of shunt response Kazui H et al, Lancet Neurology 2015 Jun; 14(6): 585-594. Yamada S et al, J Neurosurg 2016 Jul (online); DOI: 10.3171/2016.5.JNS16377.
European inph trial (2012) Multicenter trial in Europe, n=142 87 inph T (typical) based on clinical criteria 55 inph Q (questionable) 28 severe cognitive deficits; 27 non-typical gait or MRI with atrophy/infarcts/svid Shunt performed regardless of CSF TT and Rout tests Results: High dropout (19%), but 69-84% improved Only minor differences b/w T and Q both improved TT and Rout had high PPV (>90%) but low NPV (<20%) Klinge P et al, Acta Neurol Scand 2012 Sep; 126(3): 145-153. Wikkelso C et al, J Neurol Neurosurg Psychiatry 2013; 84: 562-568.
Craniomegaly in NPH? Hypothesis: NPH (or risk thereof) begins as benign external hydrocephalus in infancy Measured cranial volume by manual outlining T2WI Compared NPH (22M/29W) to controls (55M/55W) M: NPH ~ 7.5% larger (P=0.003); W: ~6.3% (P=0.002) Another study showed unexpectedly large # of inph with large HC (19.6% at 90%ile; 8.9% at 97%ile) Bradley WG et al, AJNR 2004; 25:1479-84. Wilson RK et al, JNNP 2007; 78:508-511.
Nuclear medicine cisternography? ventricular reflux, delayed accumulation or clearance Practice Guidelines for inph (2015) found insufficient evidence for its use Halperin JJ et al, Neurology 2015; 85: 2063-2071. 4 hours 24 hours 48 hours
CSF flow imaging with cine PC-MRI Gated sequence (pulse ox, ECG) to detect cardiac cycle Retrospective gating (Nitz et al, Radiology 1992; 183:395-405) Motion across gradient induces phase shift direction and magnitude of velocity Ideal plane perpendicular to flow to quantify Velocity-Encoding Gradient (VENC): max encodable v (180 ) Look for aliasing! (VENC too low) Usually 5, 10, 20 cm/sec for CSF flow studies
Hyperdynamic aqueductal flow Flow void predicts surgical outcome? (note: extent) Bradley WG et al, Radiology 1991; 178:459 FV scores associated with shunt response (P<0.003) Not reproduced (e.g. Krauss JK et al, Neurosurgery 1997; 40:67)
CSF flow in the aqueduct Orthogonal plane to aqueduct (inf) Velocity (cm/s) Flow (ml/min) Volume ( L)
CSF aqueductal flow: prognostic? SV > 42 L predicts shunt response (6/6)? Bradley WG et al, Radiology 1996; 198:523. Scanner-dependent Not reproduced (Kahlon, Neurosurgery 2007 60:124) (n=38) Flow > 18 ml/min suggests inph? Luetmer PH et al, Neurosurgery 2002 50:534. Measured in normal, MCI, AD, inph NL 8.4 ml/min / (78 beats/min) SV=54 L CBF flow did not predict SR (n=49) Dixon GR et al, Mayo Clin Proc 2002 77(6):509.
Prognostic value of MRI in inph Virhammer et al, AJNR 2014 Dec; 35:2311-2318. Studied (anatomic) imaging findings to predict 12-mo SR Logistic regression model, N=108 Significant (5%): Callosal angle, DESH (y/n), temporal horn Trend (10%): EI, FV, focal lateral ventricle bulgings Not: narrow high sulci, Sylvian F, III, WM, focal enlarged sulci
Adult-onset aqueductal stenosis Assess with high-resolution MRI and cine PC-MRI
Endoscopic Third Ventriculostomy (ETV) evaluation Case courtesy of Dr. Arastoo Vossough, Children s Hospital of Philadelphia
Chiari I malformation Anatomic definition: tonsillar descent below FM <3 mm Normal ( tonsillar ectopia ) 3-5 mm Borderline >5 mm CMI when > 15 yo >6 mm CMI when < 15 yo McVige et al, Curr Pain Headache Rep 2015 19:18. Barkovich AJ et al, AJNR 1986 7:795.
How to measure: McRae line basion (clivus) to opisthion (basiocciput) cortex to cortex (black line) Drop perpendicular to tonsil Left and Right measures Thin-section imaging (SPACE, CISS, MPRAGE) Sagittal T2WI NINDS CDE Working Group for Chiari I v0.0 https://commondataelements.ninds.nih.gov/cm.aspx
Related entities? Chiari 0: Syrinx but no hindbrain herniation? Intermittent caudal descent with valsalva?? Arachnoid veil or adhesions? Crowded FM? CMI decompression surgery treats syrinx Iskander BI et al, J Neurosurg 1998 89:212. Chiari 1.5: CMI + elongated brainstem and IV
Bony abnormalities Klippel-Feil Occipitoatlantal coalition/fusion/assimilation Tubbs RS, Neurosurg Clin N Am 2015 26:487 Small PF Odontoid orientation Retroflexion pb-c2 measure NINDS CDE Working Group for Chiari I v0.0 https://commondataelements.ninds.nih.gov/cm.aspx
Intracranial Hypotension (SIH) (acquired) Chiari Pituitary mass Sagging hypothalamus Dural enhancement Years later, still with headaches
Disordered CSF flow in CMI Disordered @ FM VENC 5-10 Sagittal plane Ventral >> Dorsal velocities Fakhri A et al, Neurosurg Clin N Am 2015 26:519
Disordered CSF flow in CMI Axial plane below tonsils (Haughton) Flow jets Synchronous Bidirectional Flow Quigly MF et al, Radiology 2004; 232:229.
Post-op imaging Further decompression?
Thank you!