Epilepsy case with focal cerebral herniation into the sigmoid sinus

Excerpt

Occult encephalocele is a well-known cause of localization-related epilepsy [1, 2] probably due to the irritative effect of mechanical traction, with secondary inflammation and gliosis [2]. However, epilepsy has not occurred in association with occult cerebral herniation into the venous sinuses (only 8 cases in 4 reports [3‐5]). Here, we present an 18-year-old female with epilepsy associated with left temporal brain herniation into the sigmoid sinus and left-sided abnormality in electroencephalography (EEG). She started to have epileptic seizures with consciousness impairment at age 5 years. She became seizure-free after medication with zonisamide and was transferred to our transition clinic at the age of 18 years. Magnetic resonance (MR) imaging demonstrated protrusion of part of the left temporal lobe and surrounding cerebrospinal fluid into the sigmoid sinus (Fig. 1a–d). [¹⁸F]Fluoro-2-deoxy-d-glucose positron emission tomography showed hypometabolism in the herniated parenchyma (Fig. 1e). MR venography showed downward compression of the left sigmoid sinus caused by the cerebral protrusion (Fig. 1f). The size of the herniation remained unchanged over 13 years (Fig. 1c, d). Recently, long-term video EEG monitoring revealed temporal intermittent rhythmic delta activity in the left temporal region, suggesting localization-related epilepsy caused by the lesion. Neuroradiologists should carefully inspect small intra-sinus lesions to avoid overlooking brain herniation into the dural venous sinuses, especially in patients with epilepsy.

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