Dissociation Between Neurovegetative Signs and Subjective Symptoms in a Case of Idiopathic Pilomotor Seizures

Objective: Pilomotor seizure (PS) is a rare subtype of simple and complex partial seizures, often related to temporal lobe epilepsy and occasionally linked to alterations of amygdala. The physiologic role played by this latter region in the coordination of autonomic responses to fear-induced emotional changes raises the question as to whether the involvement of amygdala in PS might elicit a disconnection between subjective symptoms and neurovegetative signs. Methods: We report a case of idiopathic bilateral PS studied with video electroencephalogram, polygraphic 24-hour Holter electroencephalogram, and magnetic resonance imaging, plus spectral functional magnetic resonance imaging, in which the seizures were associated with abrupt tachycardia occurring in a state of emotional neutrality, without either clouding or loss of consciousness. Results: Electroencephalogram documented PS episodes occurring during waking, rapid eyes movements, and nonrapid eye movement sleep stages. Although no morphologic alteration was detected, spectral magnetic resonance imaging visualized alterations of the metabolic ratios of N-acetylaspartate and creatine-phosphocreatine in hippocampus and amygdala, whereas no apparent involvement of the temporal lobe was found. Conclusions: These findings suggest that the limited involvement of amygdala and hippocampus in PS triggers the repertoire of fear-related sympathetic responses uncoupled from alterations in emotional status. This phenomenon supports the possibility that autonomic responses involved in fear or extreme alertness follow a kind of "ethological" modularity