2026 Poster Presentations
P180: CONTRALATERAL INTERHEMISPHERIC OCCIPITAL APPROACH FOR DEEP MEDIAL PRECUNEUS LESION IN A DRUG-RESISTANT EPILEPSY PATIENT: A CASE REPORT
Eliza Maria Bertolaccini Scolin; Ianca Barros Silva; Gabriel Mufarrej Neto; Paulo José da Mata Pereira; Paulo Niemeyer Soares Filho; Instituto Estadual do Cérebro Paulo Niemeyer
Introduction: Drug-resistant epilepsy is defined as the failure of two appropriately chosen and tolerated antiseizure medications to achieve sustained seizure freedom. In patients with MRI-visible focal lesions and concordant video-EEG monitoring, surgical resection is often the most effective treatment. Lesions in the deep medial surface of the precuneus pose surgical challenges due to the risk of damage to eloquent brain structures, particularly in the dominant hemisphere.
Objectives
- To describe the microsurgical technique of the contralateral interhemispheric occipital approach to a left precuneus lesion.
- To evaluate postoperative seizure outcomes and surgical safety in a pediatric patient with a rare epileptogenic tumor.
Methods: A 14-year-old girl presented with pharmacoresistant focal epilepsy and a left mesial parieto-occipital lesion. MRI revealed a cortico-subcortical infiltrative intra-axial lesion located in the inferomedial portion of the left precuneus gyrus, isointense on T1 and hyperintense on T2/FLAIR, without diffusion restriction, and contained sparse cystic components. Surgical resection was performed via a right occipital interhemispheric contralateral approach. Gravity-assisted positioning minimized the need for occipital lobe retraction. The interhemispheric fissure was dissected, and the falx cerebri incised near the straight sinus for direct access.
Results: The histopathological diagnosis was angiocentric glioma. Complete tumor resection was achieved with no intraoperative complications. Postoperatively, the patient remained seizure-free and exhibited no new neurological deficits.
Conclusions: Surgical treatment of lesions in the deep medial surface of the brain is challenging. Transcortical approaches carry risks due to the need for cortical resection or retraction, increasing the chance of postoperative deficits. The contralateral interhemispheric occipital route leverages gravity to naturally separate the occipital lobe from the falx, minimizing retraction. In this case, the dissection followed natural anatomical corridors—between the medial occipital surface and the falx. This approach allowed safe and effective resection of the lesion with minimal brain manipulation, supporting its utility in carefully selected cases.