Goosebumps and chills: bilateral piloerection as a manifestation of right mesial temporal 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.