Imaging for Epilepsy Diagnosis December 2, 2011

Transcription

1 Imaging for Epilepsy Diagnosis December 2, 2011 Samuel Wiebe, MD University of Calgary Canada American Epilepsy Society Annual Meeting

2 Disclosure University of Calgary Hopewell Professorship of Clinical Research Canadian Institutes for Health Research Operational Grant funding American Epilepsy Society Annual Meeting

3 Learning Objectives Why when and who to image Yield of imaging in new onset epilepsy Common underlying pathologies and prognosis Incidental findings, sensitivity and specificity American Epilepsy Society Annual Meeting

4 Why image new onset epilepsy? Detect lesions that may be causally related to epilepsy Estimate prognosis Plan appropriate care 4

5 When is Imaging Necessary? Yes Focal Seizures Focal history Abnormal exam Focal EEG abnormalities Developmental regression Generalized structural metabolic History of Status epilepticus Atypical generalized epilepsy or BECTS No or Exceptionally Childhood Absence Epilepsy Juvenile Absence Epilepsy Juvenile Myoclonic Epilepsy Typical BECTS Gaillard et al, Epilepsia

6 What does imaging contribute? New Onset Seizures CT-MRI Krumholz et al, Neurology

7 Any Abnormalities (CT) within Subgroup Study study name within Subgroup study Event within rate study and Event 95% rate CI and 95 E Event Lower Upper Event Lower Upper Event Lower Upper rate limit limit rate limit limit rate limit limit 8 Any Hopkins, 0.01 Abn Any Abn , 1993 Any van 0.03 Donselar, Abn Any Abn Any Hui, 0.11 Abn Any Abn Any Das, 0.17 Abn Any Abn , 1995 Any Edmondstone, 0.28 Abn Any Abn Any Forsgren, 0.56 Abn Any Abn ger, Any Schoenenberger, Abn Any 1994 Abn Wiebe, unpublished,

8 Significant Abnormalities (CT) p within Study Subgroup study namewithin Subgroup study Event within rate study and Event 95% rate CI and 9E Event Lower Upper Event Lower Upper Event Lower Upper rate limit limit rate limit limit rate limit limit 8 Hopkins, Sig 0.01 Abn Sig 0.01Abn r, 1993 van Sig Donselar, 0.03 Abn Sig 0.03Abn e, 1995 Edmondstone, Sig 0.04 Abn Sig 0.04Abn Hui, Sig Abn Sig 0.11Abn Das, Sig 0.17 Abn Sig 0.17Abn rger, Schoenenberger, Sig Abn Sig Abn Forsgren, Sig 0.47 Abn Sig 0.47Abn Wiebe, unpublished,

9 For adults, brain CT or MRI is probably useful. Significant yield of 10% Brain tumours Vascular lesions Neuro-infections AAN Recommendation Brain imaging using CT or MRI should be considered as part of the evaluation of adults presenting with an apparent unprovoked first seizure (Level B). Krumholz et al, Neurology

10 Common Underlying Abnormalities in Focal Epilepsy Hippocampal Sclerosis Low grade tumors: DNET, Glioma Vascular malformations: Cavernoma, AVM Malformations of cortical development Granulomas (cysticercosis) Trauma Stroke 10

11 MRI in Focal Newly Diagnosed Epilepsy 550 adults and adolescents 70% newly diagnosed Stephen LJ, et al. Epilepsia

12 MRI in Focal Newly Diagnosed Epilepsy 103 adults 100% newly diagnosed Salmenpera et al, Neurology

13 Prognostic Value of Imaging Lesion No lesion Relative Risk = 1.9 p<0.05 Hauser et al,

14 Etiology & Seizure Freedom Focal Epilepsy 550 adults and adolescents 70% newly diagnosed Stephen LJ, et al. Epilepsia

15 Incidental MRI Findings (%) Crude prevalence 2.7%, 1 in 37 people High Resolution sequence 4.3% 1 in 23 people Morris et al, BMJ

16 Four Fallible Focal Findings Asymmetric temporal horns Cysts: Arachnoid, choroid and pineal Developmental Venous Anomalies (DVAs) White matter hyperintensities 16

17 17

18 Asymmetrical Temporal Horns T1 weighted T2 weighted 18

19 Developmental Venous Anomaly 19

20 Developmental Venous Anomaly 20

21 21

22 Location of Cortical Dysplasia Type - I Type - II Frontal Lobe 32% 89% Temporal Lobe 63% 28% p 0.02 Salamon et al., Neurology 2008; 71:

23 23

24 Double cortex 24

25 Hippocampal Sclerosis T1 weighted FLAIR 25

26 FLAIR hyperintensity has low specificity 29% False positive rate Atrophy is highly specific Zero False positive in healthy people Neurology,

27 Hypothalamic Hamartoma 27

28 Cavernoma T1 weighted Gradient echo 28

29 Primary Generalized Epilepsy 29

30 Minimum T1 volumetric, High definition axial or coronal FLAIR Axial and Coronal T2 Axial and Coronal T1 Sagittal Gradient Echo Coronal perpendicular to hippocampal axis Axial Parallel to hippocampal axis 30

31 Impact on Clinical Care Imaging in epilepsy Imaging guides diagnosis, treatment, prognosis In all patients but those with idiopathic generalized epilepsy Use MRI sequences optimum for epilepsy Look for common Pathologies Beware incidental and irrelevant findings 31