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Published on: August 16, 2024
One-Stage, Limited-Resection Epilepsy Surgery for Bottom-of-Sulcus Dysplasia
Emma Macdonald-Laurs1, Wirginia J Maixner1, Catherine A Bailey1
1From the Departments of Neurology (E.M.-L., C.A.B., S.M.B., R.J.L., J.L.F., A.S.H.), Neurosurgery (W.J.M., J.Y.-M.Y., A.E.L.W., A.W.), Medical Imaging (S.A.M., M.J.K., P.F.), Anatomical Pathology (D.M., C.D.), Psychology (J.A.W.), and Anaesthesia (A.D.), The Royal Children's Hospital; Murdoch Children's Research Institute (E.M.-L., W.J.M., S.M.B., S.A.M., J.Y.-M.Y., A.E.L.W., C.D., A.D., K.P., R.J.L., A.W., A.S.H.); University of Melbourne (E.M.-L., W.J.M, S.M.B., S.A.M., J.Y.-M.Y., A.E.L.W., M.J.K., C.D., A.D., R.J.L., A.S.H.); and Florey Institute of Neuroscience and Mental Health (A.E.L.W., G.D.J., A.S.H.), Parkville, Victoria, Australia.
Objective:
To determine whether 1-stage, limited corticectomy controls seizures in patients with MRI-positive, bottom-of-sulcus dysplasia (BOSD).
Methods:
We reviewed clinical, neuroimaging, electrocorticography (ECoG), operative, and histopathology findings in consecutively operated patients with drug-resistant focal epilepsy and MRI-positive BOSD, all of whom underwent corticectomy guided by MRI and ECoG.
Results:
Thirty-eight patients with a median age at surgery of 10.2 (interquartile range [IQR] 6.0-14.1) years were included. BOSDs involved eloquent cortex in 15 patients. Eighty-seven percent of patients had rhythmic spiking on preresection ECoG. Rhythmic spiking was present in 22 of 24 patients studied with combined depth and surface electrodes, being limited to the dysplastic sulcus in 7 and involving the dysplastic sulcus and gyral crown in 15. Sixty-eight percent of resections were limited to the dysplastic sulcus, leaving the gyral crown. Histopathology was focal cortical dysplasia (FCD) type IIb in 29 patients and FCDIIa in 9. Dysmorphic neurons were present in the bottom of the sulcus but not the top or the gyral crown in 17 of 22 patients. Six (16%) patients required reoperation for postoperative seizures and residual dysplasia; reoperation was not correlated with ECoG, neuroimaging, or histologic abnormalities in the gyral crown. At a median 6.3 (IQR 4.8-9.9) years of follow-up, 33 (87%) patients are seizure-free, 31 off antiseizure medication.
Conclusion:
BOSD can be safely and effectively resected with MRI and ECoG guidance, corticectomy potentially being limited to the dysplastic sulcus, without need for intracranial EEG monitoring and functional mapping.
Classification Of Evidence:
This study provides Class IV evidence that 1-stage, limited corticectomy for BOSD is safe and effective for control of seizures.
Insights
A minimally invasive surgery called corticectomy effectively controls seizures in patients with bottom-of-sulcus dysplasia (BOSD). This procedure, guided by MRI and electrocorticography (ECoG), offers a safe and successful treatment option for drug-resistant epilepsy.
Area of Science:
- Neurosurgery
- Epileptology
- Neuroradiology
Background:
- Drug-resistant focal epilepsy often presents with subtle cortical malformations.
- Bottom-of-sulcus dysplasia (BOSD) is an MRI-detectable malformation associated with intractable seizures.
- Effective surgical targets for BOSD remain a focus of epilepsy research.
Purpose of the Study:
- To evaluate the efficacy and safety of a 1-stage, limited corticectomy for MRI-positive BOSD.
- To determine if limited resection controls seizures in patients with BOSD.
- To assess the need for additional monitoring during surgery for BOSD.
Main Methods:
- Retrospective review of patients with drug-resistant focal epilepsy and MRI-positive BOSD.
- Surgical resection guided by MRI and electrocorticography (ECoG).
- Analysis of clinical, neuroimaging, ECoG, operative, and histopathology data.
Main Results:
- Eighty-seven percent of patients achieved seizure freedom at a median follow-up of 6.3 years.
- Thirty-one patients were seizure-free and off antiseizure medication.
- Limited corticectomy to the dysplastic sulcus was effective in most cases.
Conclusions:
- 1-stage, limited corticectomy guided by MRI and ECoG is a safe and effective treatment for BOSD.
- Intracranial EEG monitoring and functional mapping may not be necessary for BOSD resection.
- This approach offers a promising surgical strategy for seizure control in BOSD patients.
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