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Epilepsy surgery

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Epilepsy surgery
Specialtyneurology, neurosurgery, epileptology

Epilepsy surgery involves a neurosurgical procedure where an area of the brain involved in seizures is either resected, ablated, disconnected or stimulated.[1] The goal is to eliminate seizures or significantly reduce seizure burden. Approximately 60% of all people with epilepsy (0.4% of the population of industrialized countries) have focal epilepsy syndromes. In 15% to 20% of these patients, the condition is not adequately controlled with anticonvulsive drugs. Such patients are potential candidates for surgical epilepsy treatment.

First line therapy for epilepsy involves treatment with anticonvulsive drugs, also called antiepileptic drugs. Most patients will respond to one or two different medication trials. The goal of this treatment is the elimination of seizures, since uncontrolled seizures carry significant risks, including injury and sudden death. However, in up to one third of patients, medications alone do not eliminate seizures, and/or cause adverse effects. In these patients, epilepsy surgery is considered as an alternate treatment method to medications.

Generally, surgery is considered in patients whose seizures cannot be controlled by adequate trials of two different medications. Epilepsy surgery has been performed for more than a century, but its use dramatically increased in the 1980s and 1990s, reflecting its efficacy in selected patients.[2][3]

Evaluation

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The evaluation for epilepsy surgery is designed to locate the "epileptic focus" (the location of the epileptic abnormality) and to determine if resective surgery will affect normal brain function. The definition of the epileptogenic zone has a fundamental role in determining the boundaries of the area that needs to be removed in order to achieve seizure freedom but also in order not to harm “eloquent cortex” (damage to this area produces neurological deficit). As the localization technology has improved, the definition of the epileptogenic zone has expanded to comprise a larger area of the brain than before.[4] Resective surgery involves the resection, or cutting away, of brain tissue from the area of the brain that consists of the epileptic focus. Physicians will also confirm the diagnosis of epilepsy to make sure that spells arise from epilepsy (as opposed to non-epileptic seizures). The evaluation typically includes neurological examination, routine EEG, Long-term video-EEG monitoring, neuropsychological evaluation, and neuroimaging such as MRI, single photon emission computed tomography (SPECT), positron emission tomography (PET). Some epilepsy centers use intracarotid sodium amobarbital test (Wada test), functional MRI (fMRI) or magnetoencephalography (MEG) as supplementary tests.[5] Recently it has been suggested that computer models of seizure generation may provide valuable additional information regarding the source of seizures.[6]

If noninvasive testing was inadequate in identifying the epileptic focus or in distinguishing the surgical target from normal brain tissue and function, then Long-term video-EEG monitoring with the use of intracranial electrodes may be required for evaluation. Brain mapping by the technique of cortical electrical stimulation or Electrocorticography are other procedures used in the process of invasive testing for certain patients.[7][8]

Once the epilepsy focus is located, the specific surgery involved in treatment is decided on. The type of surgery depends on the location of the seizure focal point. Surgeries for epilepsy treatment include, but are not limited to, the following types: temporal lobe resection, hemispherectomy, ground temporal and extratemporal resection, parietal resection, occipital resection, frontal resection, extratemporal resection, and callosotomy.[9] [10][11]

Hemispherectomy

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Hemispherectomy or hemispherotomy involves removal or a functional disconnection of most, or all of, one half of the brain typically leaving the basal ganglia and thalamus. It is reserved for people with the most catastrophic epilepsies, such as those due to Rasmussen's encephalitis. If the surgery is performed on very young patients (2–5 years old), then the remaining hemisphere may acquire some motor control of the ipsilateral body due to neuroplasticity; in older patients, paralysis results on the side of the body opposite to the part of the brain that was removed with less prospect for recovery. A visual field defect is an unavoidable side effect, typically involving a homonymous hemianopia involving loss of the half of the visual field on the same side of the disconnected brain. Because of these and other side-effects, it is usually reserved for patients having exhausted other treatment options,[12] including for children under 3 years of age who have drug-resistant epilepsy.[13]

Temporal lobe resection

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Temporal lobe resection acts as a treatment option for patients with temporal lobe epilepsy, or those whose seizure focus is in the temporal lobe. Temporal lobe seizures are the most common type of seizures for teens and young adults. The procedure involves resecting, or cutting away, brain tissue within the region of the temporal lobe in order to remove the seizure focus. Specific evaluation for temporal lobe resection requires convergent clinical, MRI, and EEG data in order to precisely pinpoint the focal area and boundaries of the focal area.[14]

The surgery has produced successful outcomes, controlling seizures in 65 percent of temporal lobe epilepsy patients. Follow-up studies suggest that the procedure also has produced positive long-term effects that illustrate 63 percent of patients still remaining seizure-free.[15] Although the procedure produces positive outcomes for patients regarding seizure control, the surgery can also produce negative outcomes such as memory impairment. Impairment depends on the hemisphere of resection; temporal lobe resection of the dominant hemisphere often causes verbal memory impairment while temporal lobe resection of the non-dominant hemisphere often causes visual memory impairment.[16]

Extratemporal lobe resection

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Extratemporal lobe resection acts as a treatment option for patients with extratemporal epilepsy, or epilepsy patients whose seizure focus is outside of the temporal lobe, and stems from either the occipital lobes, parietal lobe, frontal lobe, or in multiple lobes.[17] The evaluation for the procedure often requires more than clinical, MRI, and EEG convergence due to the variability of the seizure focus. Along with additional imaging techniques such as PET and SPECT, invasive studies may be needed to pinpoint the seizure focus. The efficacy of extratemporal lobe resection generally is less than resection of the temporal lobe. For example, in frontal lobe resections seizure freedom has been achieved in 38-44 percent of patients.[18]

Tumor Resection

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If a benign or malignant brain tumor is suspected to be the cause of seizure activity, surgical removal of the tumor may be indicated. The approach and technique is case-dependent. One study of supratentorial brain tumors in children less observed a dramatic reduction in the severity and frequency of seizures at one and four year follow-up.[19]

Laser Ablation

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See ablative brain surgery.[20]

See also

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References

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  1. ^ Jobst BC, Cascino GD (2015). "Resective epilepsy surgery for drug-resistant focal epilepsy: a review". JAMA. 313 (3): 285–93. doi:10.1001/jama.2014.17426. PMID 25602999.
  2. ^ Spencer SS, Berg AT, Vickrey BG, et al. (December 2003). "Initial outcomes in the Multicenter Study of Epilepsy Surgery". Neurology. 61 (12): 1680–5. doi:10.1212/01.WNL.0000098937.35486.A3. PMID 14694029. S2CID 21481756.
  3. ^ Krucoff, Max O.; Chan, Alvin Y.; Harward, Stephen C.; Rahimpour, Shervin; Rolston, John D.; Muh, Carrie; Englot, Dario J. (December 2017). "Rates and predictors of success and failure in repeat epilepsy surgery: A meta-analysis and systematic review". Epilepsia. 58 (12): 2133–2142. doi:10.1111/epi.13920. ISSN 1528-1167. PMC 5716856. PMID 28994113.
  4. ^ Jehi, Lara (January 2018). "The Epileptogenic Zone: Concept and Definition". Epilepsy Currents. 18 (1): 12–16. doi:10.5698/1535-7597.18.1.12. ISSN 1535-7597. PMC 5963498. PMID 29844752.
  5. ^ Rosenow, Felix; Luders, Hans (2001). "Presurgical evaluation of epilepsy". Brain. 124 (9): 1683–1700. doi:10.1093/brain/124.9.1683. PMID 11522572.
  6. ^ Goodfellow, Marc (2016). "Estimation of brain network ictogenicity predicts outcome from epilepsy surgery". Scientific Reports. 6: 29215. Bibcode:2016NatSR...629215G. doi:10.1038/srep29215. PMC 4935897. PMID 27384316.
  7. ^ Nakai, Y; Jeong, JW; Brown, EC; Rothermel, R; Kojima, K; Kambara, T; Shah, A; Mittal, S; Sood, S; Asano, E (2017). "Three- and four-dimensional mapping of speech and language in patients with epilepsy". Brain. 140 (5): 1351–1370. doi:10.1093/brain/awx051. PMC 5405238. PMID 28334963.
  8. ^ Nakai, Y; Nagashima, A; Hayakawa, A; Osuki, T; Jeong, JW; Sugiura, A; Brown, EC; Asano, E (2018). "Four-dimensional map of the human early visual system". Clin Neurophysiol. 129 (1): 188–197. doi:10.1016/j.clinph.2017.10.019. PMC 5743586. PMID 29190524.
  9. ^ Chugani, HT; Ilyas, M; Kumar, A; Juhász, C; Kupsky, WJ; Sood, S; Asano, E (2015). "Surgical treatment for refractory epileptic spasms: The Detroit series". Epilepsia. 56 (12): 1941–9. doi:10.1111/epi.13221. PMC 4679547. PMID 26522016.
  10. ^ Chugani, HT; Asano, E; Juhász, C; Kumar, A; Kupsky, WJ; Sood, S (2014). ""Subtotal" hemispherectomy in children with intractable focal epilepsy" (PDF). Epilepsia. 55 (12): 1926–33. doi:10.1111/epi.12845. hdl:2027.42/109835. PMID 25366422.
  11. ^ Tellez-Zenteno, Jose F.; Dhar, Raj; Samuel, Wiebe (2005). "Long-term seizure outcomes following epilepsy surgery: a systematic review and meta-analysis". Brain. 128 (5): 1188–1198. doi:10.1093/brain/awh449. PMID 15758038.
  12. ^ Lettori, D.; Battaglia, A.; Sacco, A.; Veredice, C.; Chieffo, D.; Massimi, L.; Tartaglione, T.; Chiricozzi, F.; Staccioli, S.; Mittica, A.; Di Rocco, C.; Guzzetta, F. (2008). "Early hemispherectomy in catastrophic epilepsy". Seizure. 17 (1): 49–63. doi:10.1016/j.seizure.2007.06.006. PMID 17689988.
  13. ^ Tsou, Amy Y.; Kessler, Sudha Kilaru; Wu, Mingche; Abend, Nicholas S.; Massey, Shavonne L.; Treadwell, Jonathan R. (2023-01-03). "Surgical Treatments for Epilepsies in Children Aged 1–36 Months: A Systematic Review". Neurology. 100 (1): e1–e15. doi:10.1212/WNL.0000000000201012. ISSN 0028-3878. PMC 9827129. PMID 36270898.
  14. ^ Noachtar, Soheyl; Borggraefe, Ingo (May 2009). "Epilepsy surgery: A critical review". Epilepsy & Behavior. 15 (1): 66–72. doi:10.1016/j.yebeh.2009.02.028. PMID 19236942. S2CID 33364764.
  15. ^ Tellez-Zenteno, Jose F.; Dhar, Raj; Samuel, Wiebe (2005). "Long-term seizure outcomes following epilepsy surgery: a systematic review and meta-analysis". Brain. 128 (5): 1188–1198. doi:10.1093/brain/awh449. PMID 15758038.
  16. ^ Bonelli, Silvia B.; et al. (2013). "Memory reorganization following anterior temporal lobe resection: a longitudinal functional MRI study". Brain. 136 (6): 1889–1900. doi:10.1093/brain/awt105. PMC 3673465. PMID 23715092.
  17. ^ "Epilepsy and Extratemporal Cortical Resection". WebMD. Retrieved 23 April 2015.
  18. ^ Ryvlin, Philippe; Cross, J Helen; Rheims, Sylvain (November 2014). "Epilepsy surgery in children and adults". The Lancet Neurology. 13 (11): 1114–1126. doi:10.1016/S1474-4422(14)70156-5. PMID 25316018. S2CID 5400708.
  19. ^ Treadwell, Jonathan R.; Wu, Mingche; Tsou, Amy Y. (2022). "Management of Infantile Epilepsies". effectivehealthcare.ahrq.gov. doi:10.23970/ahrqepccer252. PMID 36383706. Retrieved 2024-03-18.
  20. ^ "Laser Ablation Surgery for Epilepsy". Texas Children's Hospital. Archived from the original on 10 June 2012. Retrieved 8 October 2016.
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