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MRI in Temporal Lobe Epilepsy

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Clonic seizures. Tonic seizures. Atonic seizures. Tonic clonic seizures. Myoclonic seizures. Triggers. Lack of sleep. Stress. Alcohol ... – PowerPoint PPT presentation

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Title: MRI in Temporal Lobe Epilepsy


1
MRI in Temporal Lobe Epilepsy
  • Val Adams

2
Introduction
  • Functional disorder of the brain
  • Affects 0.5-1 of population in USA (Weiss et al
    1998)
  • Classifications Partial (focal, local),
    Generalised, Unclassified
  • Partial seizures include simple (no loss of
    consciousness) and complex (loss of
    consciousness)
  • Generalised seizures generalised may be
    convulsive or non-convulsive.
  • Unclassified classification for epilepsies that
    dont fit into the other classifications.

3
Generalised Seizures convulsive or
non-convulsive
  • Absence seizures
  • Clonic seizures
  • Tonic seizures
  • Atonic seizures
  • Tonic clonic seizures
  • Myoclonic seizures

4
Triggers
  • Lack of sleep
  • Stress
  • Alcohol
  • Flickering lights

5
Causes of Epilepsy
  • Mesial temporal sclerosis present in 65 of
    complex partial seizures (Jack 1994)
  • Neoplasms present in 10-13.5 (Kido 1997)
  • Adults oligodendrogliomas and astrocytomas
  • Children gangliomas and pliocystic
    astrocytomas, more rarely pleomorphic
    xanthoastrocytomas, disembryoplastic
    neuroepithelial tumours and mixed gliomas. (Kido
    1997).
  • Cortical dysplasia change from normal cortical
    pattern
  • Trauma MTS (Arrastia 2001) Cortical scarring
    (Stevens 1995)
  • Infection on increase (Friedland and Bronen
    1996)
  • Vascular malformations

6
Diagnosis
  • EEG - may need several to detect abnormal brain
    activity. To determine if epileptic in origin
  • Video EEG simultaneous monitoring and video
    recording to confirm if temporal lobe and whether
    unilateral or bilateral (Doherty and Cole 2001).
  • MRI
  • MEG
  • PET, SPECT- Not widely used may be used for
    detecting the focus in difficult cases.

7
Treatment
  • Medication not all conditions respond to the
    medication.
  • Surgery considered- if unilateral and resistant
    to drug therapy
  • Stereotactic guided radiotherapy. (Grabenbauer
    2001).
  • Vagus nerve stimulation (Alsaadi 2001)

8
MEG and Epilepsy
  • Sleep deprivation increases the likelihood of
    epileptic activity.
  • Small changes in signal detected and localised.
  • Localisation to within 2mm.
  • Expensive.

9
MRI
  • MTS loss of volume, loss of T2 weighted signal,
    loss of internal architecture
  • Tumours mass effect usually present.
    Astrocytomas have an increase in T2 signal
    greater than that seen in MTS. Some tumours may
    have calcification to aid differentiation (Kido
    1997). Not all tumours enhance.
  • Cavernous angiomas have mixed signal intensities,
    with contrast enhancement in a minimum (Kido
    1997).
  • Venous angiomas have smaller vessels draining
    into a larger vein usually enhance
  • AVMs large vessels usually visible on MRI
  • Infection High signal on T2 weighting.

10
MRI Protocols
  • Protocols vary across centres
  • Volume scan
  • High resolution coronal oblique
  • FLAIR
  • Diffusion
  • Spectroscopy
  • fMRI

11
MARIARC Protocol
  • Localiser
  • MTL localiser
  • T1 mprage volume coronal oblique
  • T2 maps coronal oblique
  • T2 tirm coronal fat sat dark fluid
  • T2 TSE ICV
  • T2 tirm coronal

12
MR Images
  • MTL Localiser for obliquity
  • 3D MPRAGE

13
MR Images
  • T2 Maps
  • T2 TIRM FS

14
MR Images
  • T2 TSE ICV
  • T2 TIRM

15
Anatomy
16
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17
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18
Voxel based morphology
  • T1 MPRAGE volumetry measurements for hippocampus,
    amygdala, temporal lobe
  • T2 TSE ICV CSF bright for simple detection of
    brain hemisphere for volume
  • Relative values to brain hemisphere used to avoid
    errors due to different brain sizes.
  • Landmarks for cut off borders.

19
Wada Test
  • Invasive procedure involving injection of
    amobarbitol sodium to anaesthetise each
    hemisphere in turn.
  • Patient woken during procedure to check if memory
    and language functions are ok.
  • Alternatives available
  • fTCD can detect relative changes in blood flow
    through the MCLs during language tasks.
  • fMRI language tasks can detect areas of
    activation.

20
T2 maps
  • Echo time varied 16 different values
  • Average of hippocampal head slice obtained
  • Regions of interest placed on both sides
  • Mean value used to determine if gliosis
    indicated.

21
Spectroscopy
  • Interictal proton CSI for presurgical
    localisation of TLE
  • Decrease N-acetylaspartate (NAA) coupled with
    increased or unchanged choline (Cho). (Ng et al
    1994).
  • Capizzano et al (2001)

22
References
  • Alsaadi, T.M., Laxer, K.D., Barbaro, N.M., Marks,
    W.J., Garcia, P.A. (2001). Vagus Nerve
    Stimulation for the treatment of Bilateral
    Independent Temporal Lobe Epilepsy. Epilepsia.
    42(7)954-956.
  • Arrastia, R.D. (2001). Neurophysiological and
    Neuroradiologic Features of Intractable Epilepsy
    after Traumatic Brain Injury in Adults
    (abstract). The Journal of the American Medical
    Association.
  • Capizzano, A.A., Vermaten, P., Laxer, K.D., Ende,
    G.R., Norman, D., Rowley, H., Matson,
    G.,Maudsley, A., SegalM.R., Weiner, M.W. (2001).
    Temporal Lobe Epilepsy Qualitative Reading of H
    MR Spectroscopic Images for Presurgical
    Evaluation. Radiology. 218144-151.
  • Doherty, C.P., Cole, A.J., Cendes, F., Letters to
    the Editor The Requirement of Ictal EEG
    Recordings Prior to Temporal Lobe Epilepsy With
    Cendes , F. Reply. Archives of Neurology . 584.
  • Duvernoy, H.M., (1999). The Human BrainSurface,
    Blood Supply, and Three Dimensional Sectional
    Sectional Anatomy. 2nd Ed. Springer-Verlag. Wien
    New York.
  • Friedland, R.J., Bronen, R.A. (1996) Epilepsy. In
    Edelman, R.R. Hesselink, J.R., Zlatkin, M.B.
    (ed)(1996). Clinical MRI Vol 1. Philadelphia
    W.B. Saunders. 703-730.
  • Grabenbauer, G.G., Reinhold, C., Kerling, F.,
    Muller, R.G., Lambrecht, U., Pauli, E.,
    Ganslandt, O., Sauer, R., Stefan, H.(2002).
    Fractionated Stereotactically guided
    Radfiotherapy of Pharmacoresistant Temporal Lobe
    Epilepsy. Acta Neurochir. Supplement 8465-70.
  • Jack, C.R., Krecke, K.N., Cascino, G.D.,
    Sharbrough, F.w., Obrien, P.C., Parisi, J.E.,
    (1994). Diagnosis of Medial Temporal Sclerosis
    with Conventional versus Fast Spin-Echo MR
    Imaging. Radiology 192123-127.
  • Jackson, G.D., Berkovic, S.F., Duncan, J.S., et
    al (1993). Optimizing the Diagnosis of
    Hippocampal Sclerosis using MR Imaging. American
    Journal of Neuroradiology. 14753-762.
  • Kido, D.K., Tien, R.D., Lee, B., Bahn, M.M.
    (1997). Hippocampal Pathology. Neuroimaging
    Clinics of North America.
  • Ng, T.C., Comair, Y.G., Xue, M., So, N., Majors,
    A., Kolem, H., Luders, H.,Modic, M. (1994).
    Temporal Lobe Epilepsy Presurgical evaluation
    with Proton Chemical Shift Imaging. Radiology
    193463-472.
  • Stevens, J.M. (1995). Imaging in Epilepsy.
    Clinical MRI. 5(1)14-23.
  • Uematso, S. (1990). Surgical Management of
    Complex Partial Seizures. Journal of the American
    Medical Association. 264(6)734.
  • Weiss, K.L., Figueroa, R.E., Allison, J. (1998).
    Functional MRI in Patients with Epilepsy.
    Magnetic Resonance Imaging Clinics of North
    America New Techniques in MR Imaging.
    6(1)95-112.
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