94 - Transtentorial Herniation from a Rare Tentorial Incisura Defect: A Case Report for Clinical and Neuroanatomical Education

Poster Board Number: 94
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Abstract Body : We present a case report of a 36-year-old woman with a history of Juvenile Myoclonic Epilepsy, prosopagnosia, and visual hallucinations. This case is proposed to be used for clinically applied neuroanatomical education. Findings from a non-contrast Computed Tomography (CT) scan and a 3-Tesla Magnetic Resonance Imaging (3T-MRI) are presented here, along with a three-dimensional (3D) reconstruction using Amira and 3DSlicer. The 3T-MRI showed an approximately 11.5 mm defect of the left edge of the tentorial incisura. Herniation of the left posterior mesial temporal lobe and parasagittal occipital lobe were identified. The rest of the structures were unremarkable. As the patient’s neurological exam was normal, her seizures were generally well-controlled, and she displayed neither radiological signs nor symptoms suggesting high intracranial pressure, the medical team continued pharmacological treatment for epilepsy with monitoring. A non-contrast CT scan conducted 5 years after the 3T-MRI indicated that the herniation was unchanged. Reports of tentorial incisura defects with dual-lobe herniations are exceedingly rare in the published literature. As far as we know, this is the first repeat-imaging report demonstrating a stable and chronic unilateral occipito-temporal herniation from a tentorial incisura defect. Radiological and anatomical education around herniations often focus on patients requiring urgent intervention from high intracranial pressure. This case is important for clinical as well as educational purposes. In particular, recognition of these conditions are important to prevent unnecessary neurosurgical intervention. Currently, we cannot definitively pinpoint whether the patient’s clinical symptoms are caused by the lesions seen on imaging. This case report is an excellent candidate for case-based learning to help trainees problem-solve on how to investigate whether these lesions are developmental or pathological. Our team plans to follow up with this patient by administering a battery of visuospatial and facial-recognition neuropsychological tests to help us examine if the radiological findings in the brain MRI and CT correlate with functional outcomes. Diffusion Tensor Imaging (DTI) would also be the next step to help determine if fibre tracts were displaced during development or are pathological in nature.