• Isolated bilateral piloerection is a rare manifestation of autonomic seizures, which can lead to diagnostic and localization challenges. • We report a 21-year-old male with drug-resistant epilepsy, whose seizures consisted of bilateral piloerection and chills followed by coughing. • Stereo-EEG localized seizure onset to the right amygdala and hippocampus, and cortical stimulation of both regions elicited the patient’s autonomic semiology, representing a unique report to directly demonstrate this phenomenon through stimulation. • This case provides rare evidence that the amygdala, in addition to the hippocampus, contributes to pilomotor seizures, likely reflecting its role in coordinating autonomic responses to fear-related stimuli. • Recognition of autonomic semiologies such as piloerection can guide targeted sEEG implantation, improve localization accuracy, and improve outcomes in drug-resistant epilepsy. Ictal piloerection is a rare autonomic seizure manifestation that can obscure localization and mimic non-epileptic conditions. We report a 21-year-old man with drug-resistant focal epilepsy whose seizures consisted of isolated bilateral piloerection and chills followed by coughing. MRI demonstrated right mesial temporal sclerosis, and FDG-PET showed concordant hypometabolism. Scalp EEG suggested a right temporal onset. Stereo-electroencephalography recorded eleven habitual seizures with electrographic onset in the right amygdala and hippocampus preceding the clinical symptoms. Notably, cortical stimulation of both structures reproducibly elicited bilateral piloerection, directly confirming their role in symptom generation. Following laser ablation of the right amygdala and hippocampus, the patient remains seizure-free at ten months. This case is unique in providing intracranial and stimulation-based evidence for bilateral ictal piloerection arising from a unilateral mesial temporal focus involving both the amygdala and hippocampus. Recognition of this distinctive autonomic semiology and its localization is critical, as it refines localization, guides strategic sEEG implantation, and underscores the need for comprehensive limbic coverage in surgical planning to optimize seizure freedom.
Fowler et al. (Wed,) studied this question.