Abstracts

Rationale: Hypothermic hamartoma (HH) is a rare neurodevelopmental benign malformation. It typically presents with a wide variety of epileptic semiology ranging from focal to catastrophic secondary generalized seizures like Lennox Gastaut syndrome with the hallmark semiology being gelastic seizures at onset. Seizures are typically refractory to anti-seizure medication (ASM) and associated with severe cognitive and behavioral decline, especially if left untreated.

Methods: Clinical data, brain images and electrophysiological data was reviewed retrospectively.

Results: Our patient is a 3-year-old who began having seizures at 22 months of age. Initially described by parent as “Becomes frozen, then all over stiffening and shaking;” no gelastic seizures were reported. Development was appropriate, although there were some concerns for speech delay. Initial routine EEG was normal. Inpatient video EEG showed bilateral synchronized versus generalized epileptiform discharges with right hemispheric predominance. He then returned for 48 hours vEEG, and seizures were captured. Seizure semiology at that time was described as non-versive head turn to the right and behavioral arrest, with poorly localized/diffuse onset on EEG; however, seizure evolution was better appreciated over the right frono-temporal area. Frequent right mid-temporal interictal discharges with broad fields were noted at times during his video EEG. MRI brain showed HH. PET scan was obtained and revealed hypometabolism in the anterior right temporal lobe extending posteriorly to the temporal parietal junction.

A neurodevelopmental evaluation conducted at 40 months old indicated that the patient’s cognitive, receptive and expressive language, and fine-and gross-motor skills were moderately to severely impaired for age. Due to the non-traditional clinical presentation, we decided to peruse SEEG investigation to further define epileptogenic and symptomatic onset zone. Our hypothesis-driven SEEG approach included the right mesial temporal cortex, right lateral temporal cortex and right parietal cortex, as well as coverage for the HH.

During SEEG, 27 electroclinical seizures lasting less than 40 seconds were captured, each with onset in contacts located in HH with rapid spread to amygdala, temporal-parietal-occipital association cortex, prelingual region, fusiform and angular gyri, and mid temporal gyrus. Clinically, we observed eye fluttering/blinking, non-versive head turn to the right, behavioral arrest. Electrical stimulation reproduced the patient’s habitual seizure with stimulation in the HH. He then underwent laser ablation of HH. At the time this abstract was written, he had been seizure free for more than 3 months following surgery.

Conclusions: To our knowledge, we present the first of case of HH with a non-gelastic seizure semiology and an early ictal network in the posterior cortex. Prior SEEG investigations didn’t address the posterior propagation. Our case provides evidence that patients with HH may present with different seizure semiology than is typically expected. This information is critical for early identification and treatment and can lead to seizure freedom and improvement in neurocognitive outcome.

Funding: Please list any funding that was received in support of this abstract.: none.