• History and Examination

    In your surgical epilepsy conference, your epileptologists present a 29 year old woman with medically refractory epilepsy. Her seizures consist of an initial feeling of a rising epigastric sensation (like she’s on a roller coaster), usually followed by an inability to articulate, but with preserved language comprehension. There is typically no aura or manual automatisms. She does not lose awareness, and there is no convulsive activity. EEG during the seizures is non-localizing and non-lateralizing. MEG shows dipoles in the left insular and medial frontal region. Her MRI is shown below and is remarkable for a lesion in the left superior parasagittal area. It appears calcified and does not enhance. SPECT and PET scans do not provide further helpful information for localizing the seizures.

    Figure 1

    Figure 2

    Figure 3

    1. Based on this description of her seizures, how should they be classified?

    2. Based on the seizure semiology, what is the most likely onset area?

    3 . What is the next best step for ascertaining the origin of onset of her seizures?

    4. You perform a targeted resection of the lesion and a small area of tissue around the lesion using an interhemispheric approach with electrocorticography guidance. A more extensive resection in and anterior to this region would lead to what deficit(s)?

    5. Which of the following describes you?

    6. I practice in one of the following locations.

    7. Comments
     
    • ‚ÄčNeuronavigation in this small lesions allows a more precise craniotomy in size and site. 
    • Thank you for a nice case
    • Question 1: NOMENCLATURE from ILAE – 2016 is simple and straightforward >> choice 1.Primary generalized can only be name given @ clinical presentation, but on EEG, there will at least be a few nanosecond gap between the focal site of origin to global spread choice 2: complex partial when dissected gets a new name: focal onset with impaired awareness choice 3: focal with retained awareness is simple partial choice 4: Complex partial with secondary generalization dissected to be named: focal to bilateral tonic clonic
      Also, the presentation has a component fitting with the name 'autonomic seizure' in the form of epigastric raising.. to sum up it could be FOCAL SEIZURE WITH RETAINED AWARENESS WITH AN AUTONOMIC COMPONENT !

      Question 2: ADDITIONAL ANATOMY INFO: normally nucleus cuneiformis in the brainstem inhibits our perception of visceral movements, otherwise we get distracted if all of our abdominal peristalsis reaches the cortex. Also, in one experimental stimulation of human rectum produces bright spots in the POSTERIOR insula.

      Question 3: We know from the end of the case it was not TLE, but PET AND SPECT are known to be useful in evaluating TLE. pre-ictal SPECT is more useful as hypoperfusion is better picked up with this scan. SPECT is repeated up to 4 hours after the seizure. Hypoperfusion is better picked up with this scan. It is more sensitive in cerebrovascular disease and dementia than a seizure, which does not mean it is not useful in a seizure. Also, only when SPECT is fused with MRI to make it SISCOM the sensitivity becomes 80%. When it comes to protocol all depends on what the multi-disciplinary team wants !

      Question 4: The connections between SMA and the OPERCULAR speech area are lost hence MUTISM 
    • Excellent case. I await an answer. 
    • why taking out the small L SMA lesion? 
    • I have no recent experience with epilepsy surgery, nor have I reviewed the topic recently. I do like the cases....keep them coming
    •  

     

    Case Explanation:

    Commentary (1)
    Seizures can be either simple or complex, and partial or general. Simple seizures do not cause alteration of consciousness, whereas complex seizures do. Partial seizures affect only one localized region of the brain, whereas general seizures arise from several brain regions. Because her seizures do not cause loss of awareness they are simple. Because her symptoms are stereotyped, with focal findings (expressive language difficulty), they are partial. Partial seizures (either simple or complex) can secondarily generalize, which occurs when epileptiform activity spreads beyond the onset zone to include other regions in both hemispheres. Note that these traditional terms for seizure classification are being replaced with a new terminology, as described below in Berg et al.

    Commentary (2)
    The rising epigastric sensation is typically attributed to onset in the insular region, and the expressive language dysfunction suggests dominant inferior frontal origin. Thus a parsimonious explanation for the combination of these symptoms localizes onset to the insular/opercular area in the dominant hemisphere.

    Commentary (3)
    The non-invasive workup (seizure semiology, MRI, MEG) has narrowed down the seizure onset zone to the left insula, operculum, and/or mesial frontal region. Functional MRI and Wada testing can help lateralize language function and (especially with Wada) memory function, but neither are useful for localizing seizures. A repeat SPECT is unlikely to help. Either craniotomy for grid implant or stereo-EEG implant can help localize seizures. In this case, given the deep structures (insula, mesial frontal region) that need to be sampled, many centers would prefer stereo-EEG over grids and strips, but that choice is specific to the center’s experience.

    Commentary (4)
    This lesion is in the dominant supplementary motor area (SMA), a region on the medial aspect of the frontal lobe just anterior to primary motor territory. SMA syndrome consists of contralateral weakness (usually thought of more as difficulty initiating movements than actual weakness) that is usually temporary (days to weeks). In the dominant hemisphere, patients can also evidence temporary mutism. Permanent weakness could occur after primary motor damage. Sensory deficits typically occur after primary sensory region damage. Expressive and receptive aphasia can occur after damage to the language regions in the dominant inferior frontal and superior temporal regions. Verbal memory deficit can occur after dominant mesial temporal damage.

     

    References:

    • Berg, A. T., Berkovic, S. F., Brodie, M. J., Buchhalter, J., Cross, J. H., van Emde Boas, W., et al. (2010). Revised terminology and concepts for organization of seizures and epilepsies: report of the ILAE Commission on Classification and Terminology, 2005-2009. Epilepsia, 51(4), 676–685. 
    • Isnard et al., “Clinical manifestations of insular lobe seizures: a stereo-encephalography study.” Epilepsia 45(9): 1079-1090, 2004.
    • Cohen-Gadol et al., “Partial epilepsy presenting as episodic dyspnea: a specific network involved in limbic seizure propagation.” J Neurosurg 100(3): 565-576, 2004.
    • Potgieser, A. R. E., de Jong, B. M., Wagemakers, M., Hoving, E. W., & Groen, R. J. M. (2014). Insights from the supplementary motor area syndrome in balancing movement initiation and inhibition. Frontiers in Human Neuroscience, 8, 960. 

     

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