Epilepsy

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Epilepsy is a common chronic seizure disorder.

General

  • Epilepsy = seizures that are "idiopathic", i.e. no brain tumour, no mass lesion, no brain injury.
  • Most common form: temporal lobe epilepsy.[1]

Etiology

Syndromic:

Tumour:

Types

Features:[4]

  • Temporal lobe epilepsy
  • Mesial temporal sclerosis = scarring of the medial temporal lobe.
    • Involves: hippocampus, parahippocampal gyrus and amygdala.
  • Granule cell dispersion

Hamartia

  • Small collection of ectopic glioneuronal cells.
    • Morpholology resembling oligodendroglial-like cells. [5]
  • Mostly amygdala, less common in hippocampus or temporal lobe.
  • Can coexist with focal cortical dysplasia.

Focal cortical dysplasia (FCD)

  • Localized malformations of the cortex.
  • Frequently associated with epilepsy in children.
  • Includes cortical dyslamination, cytoarchitectural changes and white matter abnormalities.
  • Current consensus: ILAE classification scheme 2011 [6](based on previous classification by Palmini 2004):


  • Type I FCD (focal)
    • Ia: Abnormal radial cortical lamination.
    • Ib: Abnormal tangential cortical lamination.
    • Ic: Abnormal radial and tangential cortical lamination.


  • Type II FCD (focal)
    • IIa: Presence of dysmorphic neurons.
    • IIb: Presence of dysmorphic neurons and balloon cells.


  • Type III FCD (associated with other lesion)
    • IIIa: FCD associated with hippocampal sclerosis.
    • IIIb: FCD adjacent to a brain tumor.
    • IIIc: FCD adjacent to vascular malformation.
    • IIIc: FCD associated with previous injury (trauma, inflammation...).


Hippocampal sclerosis

  • Most frequent histopathology in temporal lobe epilepsy (33% of all epilepsy surgery specimen).
  • ILAE classification for hippocampus specimen:[7]
    • ILAE type 1: cell loss predominantly in CA1 and CA4 sectors.
    • ILAE type 2: predominant CA1 neuron loss and gliosis.
    • ILAE type 3: CA4 predominant neuronal cell loss and gliosis.

Clinic: ILAE type 1: benefit from epilepsy surgery.

Notes:

  • Gliosis withot neuronal loss is not considered hippocampal sclerosis.

Granule cell dispersion

  • Affects dentate gyrus.
  • Observed in up to 40% specimen with hippocampal sclerosis.
  • Clinico-pathological classification:[8]
    • Granule cell pathology (GCP) Type 1: Substantial granule cell loss.
    • Granule cell pathology (GCP) Type 2: Cell dispersion, ectopic neurons or clusters of neurons in the molecular layer or bi-lamination.

Clinic:

  • Association with longer epilepsy duration.

DDx:

Sudden unexpected death in epilepsy

  • Abbreviated SUDEP.

Diagnosis:

Epidemiology:[9]

  • Typically poorly controlled epilepsy.
  • Incidence: 0.09-9 per 1000 patient-years.

See also

References

  1. URL: http://emedicine.medscape.com/article/342150-overview. Accessed on: 20 November 2010.
  2. Cataltepe, O.; Turanli, G.; Yalnizoglu, D.; Topçu, M.; Akalan, N. (Apr 2005). "Surgical management of temporal lobe tumor-related epilepsy in children.". J Neurosurg 102 (3 Suppl): 280-7. doi:10.3171/ped.2005.102.3.0280. PMID 15881751.
  3. Im, SH.; Chung, CK.; Cho, BK.; Lee, SK. (Mar 2002). "Supratentorial ganglioglioma and epilepsy: postoperative seizure outcome.". J Neurooncol 57 (1): 59-66. PMID 12125968.
  4. MUN. 15 November 2010.
  5. Kasper, BS.; Stefan, H.; Buchfelder, M.; Paulus, W. (Jan 1999). "Temporal lobe microdysgenesis in epilepsy versus control brains.". J Neuropathol Exp Neurol 58 (1): 22-8. PMID 10068310.
  6. Blümcke, I.; Aronica, E.; Miyata, H.; Sarnat, HB.; Thom, M.; Roessler, K.; Rydenhag, B.; Jehi, L. et al. (Mar 2016). "International recommendation for a comprehensive neuropathologic workup of epilepsy surgery brain tissue: A consensus Task Force report from the ILAE Commission on Diagnostic Methods.". Epilepsia 57 (3): 348-58. doi:10.1111/epi.13319. PMID 26839983.
  7. Blümcke, I.; Thom, M.; Aronica, E.; Armstrong, DD.; Bartolomei, F.; Bernasconi, A.; Bernasconi, N.; Bien, CG. et al. (Jul 2013). "International consensus classification of hippocampal sclerosis in temporal lobe epilepsy: a Task Force report from the ILAE Commission on Diagnostic Methods.". Epilepsia 54 (7): 1315-29. doi:10.1111/epi.12220. PMID 23692496.
  8. Blümcke, I.; Kistner, I.; Clusmann, H.; Schramm, J.; Becker, AJ.; Elger, CE.; Bien, CG.; Merschhemke, M. et al. (May 2009). "Towards a clinico-pathological classification of granule cell dispersion in human mesial temporal lobe epilepsies.". Acta Neuropathol 117 (5): 535-44. doi:10.1007/s00401-009-0512-5. PMID 19277686.
  9. Tomson, T.; Nashef, L.; Ryvlin, P. (Nov 2008). "Sudden unexpected death in epilepsy: current knowledge and future directions.". Lancet Neurol 7 (11): 1021-31. doi:10.1016/S1474-4422(08)70202-3. PMID 18805738.