gloria j. guzmán, md, msc robert mckinstry, md, phd matthew smyth, md, faans, facs, faap
TRANSCRIPT
Imaging Primer for the Identification of Focal Cortical Dysplasias
eEdE-178-7091, Control #421Gloria J. Guzmán, MD, MScRobert McKinstry, MD, PhD
Matthew Smyth, MD, FAANS, FACS, FAAP
Financial DisclosuresGloria Guzman and Matthew Smyth: NoneRobert McKinstry:
Siemens Healthcare: Honoraria, travel, lodging, meals >$10,000
PURPOSE
To create an imaging primer that will allow easier radiographic identification of focal cortical dysplasias
APPROACH/METHODS
What is focal cortical dysplasia (FCD)?1, 2Focal cortical dysplasia is a derangement of cortical
development, including neuronal proliferation, migration, differentiation or programmed cell death
Both genetic and acquired factors are involved, although the pathogenesis is still being investigated
Multiple grading systems exist. In general, three types are recognized (I, II and III), each with associated sub-classifications. We will focus on FCD type I and II, which are isolated lesions. FCD type III are associated with other findings, such as tumor, vascular malformations or sclerosis
1. Colombo et at. Imaging of malformations of cortical development. Epileptic Disord 2009; 11 (3): 194-2052. Blümcke et al. The clinicopathologic spectrum of focal cortical dysplasias: A consensus classification proposed by an ad
hoc Task Force of the ILAE Diagnostic Methods Commission. Epilepsia, 52(1):158–174, 2011
Imaging findings of FCD Type I1, 2
Temporal predilection, more common in adultsProminent lobar/sublobar hypoplasia/atrophy, frequently associated with volume loss of the subcortical white matter:
Moderately increased signal on T2WI and heavily T2W FLAIR images
Decreased signal on T1W images, either 3D volumetric Gradient Echo T1W or heavily T1W Inversion Recovery (IR) images
Mild blurring at the grey/white matter junction with normal cortical thickness
Abnormal gyral/sulcal patterns can be presentMost commonly associated with dual pathology (+ hippocampal
sclerosis)1, which will not be discussed in this presentation, as it is “not yet comprehensively defined”21. Colombo et at. Imaging of malformations of cortical development. Epileptic Disord 2009; 11 (3): 194-205
2. Blümcke et al. The clinicopathologic spectrum of focal cortical dysplasias: A consensus classification proposed by an ad hoc Task Force of the ILAE Diagnostic Methods Commission. Epilepsia, 52(1):158–174, 2011
Imaging findings of FCD Type II1,2
Extratemporal with predilection of frontal lobes, more common in children
Transmantle sign: The white matter signal alterations taper towards the ventricle, reflecting the involvement of radial glial-neuronal bands
Increased cortical thicknessPronounced blurring of the gray matter/white matter
junction both on T1WI and T2WI (due to increase disturbance in cortical structures vs. FCD I)
Increased subcortical white matter signal on T2WI and heavily T2W FLAIR Increased T2-signal within affected cortex is far more common
in FCD type II than in FCD type I; the grey matter remains hypointense 1. Colombo et at. Imaging of malformations of cortical development. Epileptic Disord 2009; 11 (3): 194-205
2. Blümcke et al. The clinicopathologic spectrum of focal cortical dysplasias: A consensus classification proposed by an ad hoc Task Force of the ILAE Diagnostic Methods Commission. Epilepsia, 52(1):158–174, 2011
Imaging findings of FCD Type II1,2
Decreased signal on T1W images, either 3D volumetric Gradient Echo T1W or heavily T1W Inversion Recovery (IR) images
Abnormal cortical gyration and sulcation, better evaluated on 3D surface rendering
Focal enlargement of the subarachnoid spaces seem to point at the dysplastic lesion
In a number of cases, a much sharper demarcation between the cortex and the adjacent white matter may be found
1. Colombo et at. Imaging of malformations of cortical development. Epileptic Disord 2009; 11 (3): 194-2052. Blümcke et al. The clinicopathologic spectrum of focal cortical dysplasias: A consensus classification proposed by an ad
hoc Task Force of the ILAE Diagnostic Methods Commission. Epilepsia, 52(1):158–174, 2011
Detailed analysis of following structures by imaging:Increased cortical thicknessBlurring of the grey/white matter junction with
disappearance of subcortical white matter digitations White matter signal abnormalities with or without
extension all throughout the cortical mantle (the transmantle sign)
Focal enlargement of subarachnoid space adjacent to cortical anomaly
Grey and/or white matter signal changesAbnormal gyral/sulcal patternsFocal and/or lobar hypoplasia/atrophy
The Checklist
Detailed analysis of the following structures:Increased cortical thickness
Detailed analysis of the following structures:Blurring of the grey/white matter junction with
disappearance of subcortical white matter digitations
Detailed analysis of the following structures:White matter signal abnormalities with or without
extension all throughout the cortical mantle (the transmantle sign)
Detailed analysis of the following structures:Focal enlargement of the subarachnoid
spaces
Grey and/or white matter signal changes
Detailed analysis of the following structures:
Detailed analysis of the following structures:Abnormal gyral/sulcal patterns
Detailed analysis of the following structures:Focal and/or lobar hypoplasia/atrophy
Caveats in analysis:Cortical thickening should only be reported if
the cortex appears thick on both T1W and T2W sequences that are windowed for high levels of contrast, in at least two planes
Blurring and cortical thickness should be evaluated specifically and individually on: T2WI3D volumetric Gradient Echo T1WI Heavily T1W Inversion Recovery (IR) images
Analysis in infants1:In FCD, the subcortical white matter may sometimes be
isointense to cortex (and, therefore, appear as blurring or thick cortex) on T1WI but will look hyperintense to cortex on T2WI, delineating the junction with the cortex and showing true cortical thickness, THUS YOUR T2 SEQUENCE IS THE MOST IMPORTANT
Before 6 months of age, the hypointensity on T2W images of the cortical dysplasia is very clear in contrast to the hyperintensity of the unmyelinated white matter
If the first MR study is obtained between ages of 6 and 18 months, a second scan will be required when myelination is largely completed (after the age of 30 months)
1. Colombo et at. Imaging of malformations of cortical development. Epileptic Disord 2009; 11 (3): 194-205
FINDINGS/DISCUSSION
CASES
Case #1
Where are the findings? Have you used your checklist?
√ Cortical thickening√ Blurring of grey/white matter junction
17 y/o with intractable dominant motor cortical seizures
No seizures since surgery 5/2008
Continues on Trileptal at 600 mg twice daily
Case #1
Subtype of FCD not reported / not available
Case #2
Where are the findings? Have you used your checklist?
√ Cortical thickening√ Blurring of grey/white matter junction
13 y/o with medically refractory epilepsy
No seizures since surgery 7/2009On Dilantin, last active 10/2010
Case #2
Case #3
Where are the findings? Have you used your checklist?
√ Cortical thickening√ Blurring of grey/white matter junction√ Abnormal white matter signal
10 y/o with medically intractable seizures
No seizures since surgery 10/2007 Weaned off Lamictal 2010
Case #3
Case #4
Where are the findings? Have you used your checklist?
√ Cortical thickening√ Blurring of grey/white matter junction√ Prominent subarachnoid space
11 y/o with seizures refractory to medical treatment
No seizures since surgery 6/2008
Off meds since 9/2009
Case #4
Case #5
Where are the findings? Have you used your checklist?
√ Cortical thickening√ Blurring of grey/white matter junction
Case #5
2 y/o with intractable seizures, surgery on 7/2013
Since surgery has had a new type of seizure involving his arms going up and who body stiffening without eye deviation
Repeat MRI showed residual FCD
Case #6
√ Blurring of grey/white matter junction
Where are the findings? Have you used your checklist?
19 month old with intractable seizures, surgery on 3/2014
No seizures since surgery
Weaning off Lamictal
Case #6
Case #7
Where are the findings? Have you used your checklist? √ Cortical
thickening√ Blurring of grey/white matter junction√ Abnormal grey and white matter signal
5y/o with medically intractable epilepsy
Improved, but persistent seizures after surgery 10/08
On Keppra, Lamictal, Strattera and Valium
Case #7
Case #8
Where are the findings? Have you used your checklist?
√ Abnormal gyral pattern√ Blurring of grey/white matter junction√ Abnormal grey and white matter signal√ Prominent subarachnoid space
16 y/o, unfortunately, lost to follow-up, no clinical history post-op available
Case #8
Subtype of FCD not reported / not available
Case #9
Where are the findings? Have you used your checklist?
√ Blurring of grey/white matter junction
17 y/o with medically intractable epilepsy
Worsening seizures since surgery on 12/12, considering NeuroPace treatment
Case #9
Subtype of FCD not reported / not available
Case #10
Where are the findings? Have you used your checklist?
√ Cortical thickening√ Blurring of grey/white matter junction√ Abnormal white matter signal
9 y/o with medically intractable seizures, surgery on 6/2011
Seizure-free and off Valproic Acid
Case #10
Surgical outcomesSeveral articles have been published about
patient outcomes after surgical removal of suspected epileptic foci, a few specifically relating to FCD
Articles report approximately 70% success rate in achieving seizure-free status (Engle Epilepsy Outcome Scale I). Most failures are associated with incomplete resection of seizure foci, either due to technique or nearness to critical functional areas3
3. Cohen-Gadol, AA, et al. "Long-term outcome after epilepsy surgery for focal cortical dysplasia." Journal of neurosurgery 101.1 (2004): 55-65.
SUMMARY
In summaryFocal cortical dysplasias can be hard to identify
on imaging, thus USE THE CHECKLIST to help guide you in the identification of these lesions
Since surgical treatment is currently the same regardless of FCD type, correct imaging identification of isolated FCD on imaging is more important than histologic classification for surgical planning and decision-making
Correlation with functional imaging, such as PET-Brain or SPECT-Brain is very useful in localizing these lesions
ReferencesColombo N et al. Imaging of malformations of
cortical development. Epileptic Disord 2009: 11(3): 194-205
Blümcke et al. The clinicopathologic spectrum of focal cortical dysplasias: A consensus classification proposed by an ad hoc Task Force of the ILAE Diagnostic Methods Commission 1. Epilepsia 2011: 52(1), 158-174
Cohen-Gadol AA, et al. "Long-term outcome after epilepsy surgery for focal cortical dysplasia." Journal of Neurosurgery” (2004): 101.1, 55-65
Thank you for your attention!