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Published on: May 16, 2019
Seizure outcome in drug-resistant epilepsy in the setting of polymicrogyria
Thandar Aung1, Jin Bo2, William Bingaman3
1Epilepsy Center, Neurological Institute, Cleveland Clinic, 9500 Euclid Avenue, Desk S60, Cleveland, OH 44195, United States; University of Pittsburgh Epilepsy Center, University of Pittsburgh Medical Center, Pittsburgh, PA, United States.
Objective:
We aimed to analyze seizure outcomes and define ictal onset with intracranial electroencephalography (ICEEG) in patients with polymicrogyria (PMG)-related drug-resistant epilepsy (DRE), considering surrounding cortex and extent of surgical resection.
Methods:
Retrospective study of PMG-diagnosed patients (2001 to June 2018) at a single epilepsy center was performed. Primary outcome was complete seizure freedom (SF), based on Engel classification with follow-up of ≥ 1 year. Univariate analyses identified predictive clinical variables, later integrated into multivariate Cox proportional hazards models.
Results:
Thirty-five patients with PMG-related DRE (19 adults/16 pediatric: 20 unilateral/15 bilateral) were studied. In surgical group (n = 23), 52 % achieved SF (mean follow-up:47 months), whereas none in non-resective treatment group (n = 12) attained SF (mean follow-up:39.3 months) (p = 0.002). In surgical group, there were no significant differences in SF, based on the laterality of the PMG [uni or bilateral,p = 0.35], involvement of perisylvian region(p = 0.714), and extent of the PMG resection [total vs. partial,p = 0.159]. Patients with ictal ICEEG onset in both PMG and non-PMG cortices, and those limited to non- PMG cortices had a greater chance of achieving SF compared to those limited to the PMG cortices.
Conclusion:
Resective surgery guided by ICEEG for defining the epileptogenic zone (EZ), in DRE patients with PMG, leads to favorable seizure outcomes. ICEEG-guided focal surgical resection(s) may lead to SF in patients with bilateral or extensive unilateral PMG. ICEEG aids in EZ localization within and/or outside the MRI-identified PMG. Complete removal of PMG identified on MRI does not guarantee SF. Hence, developing preimplantation hypotheses based on epileptogenic networks evaluation during presurgical assessment is crucial in this patient population.
Insights
Intracranial electroencephalography (ICEEG)-guided surgery for polymicrogyria (PMG)-related drug-resistant epilepsy (DRE) improves seizure freedom. Identifying the epileptogenic zone (EZ) within or outside the PMG is key for successful surgical outcomes.
Area of Science:
- Neuroscience
- Epileptology
- Neurosurgery
Background:
- Polymicrogyria (PMG) is a cortical malformation associated with drug-resistant epilepsy (DRE).
- Defining the precise epileptogenic zone (EZ) in PMG-related DRE is challenging, impacting surgical planning and outcomes.
- Intracranial electroencephalography (ICEEG) offers detailed ictal onset localization.
Purpose of the Study:
- To analyze seizure outcomes in patients with PMG-related DRE.
- To define the ictal onset using ICEEG, considering surrounding cortex and surgical resection extent.
- To identify predictors of seizure freedom (SF) in this patient cohort.
Main Methods:
- Retrospective study of 35 patients with PMG-related DRE (2001-2018).
- Primary outcome: complete seizure freedom (SF) via Engel classification (≥1 year follow-up).
- Univariate and multivariate Cox proportional hazards models used to identify predictive clinical variables.
Main Results:
- In the surgical group (n=23), 52% achieved SF, compared to 0% in the non-resective group (n=12) (p=0.002).
- Seizure freedom was not significantly different based on PMG laterality, perisylvian involvement, or resection extent (total vs. partial).
- Patients with ictal onset in both PMG and non-PMG cortices, or only non-PMG cortices, had better SF chances than those with onset solely within PMG cortices.
Conclusions:
- Resective surgery guided by ICEEG for EZ definition in PMG-related DRE leads to favorable seizure outcomes.
- ICEEG-guided focal resections can achieve SF even in complex PMG cases (bilateral or extensive unilateral).
- Complete resection of MRI-visible PMG does not guarantee SF; preimplantation hypothesis development based on epileptogenic network evaluation is crucial.
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01:13Seizures: Classification
Seizures are typically classified into two main categories: focal and generalized seizures.
Focal Seizures
Focal seizures originate from specific regions of the brain. These seizures are further sub-classified into two types: