History of simple febrile seizures is associated with hippocampal abnormalities in adults

Summary Background: It is unclear whether the hippocampal abnormality in temporal lobe epilepsy (TLE) is a consequence or the cause of afebrile or febrile seizures (FSs). We investigated whether hippocampal abnormalities are present in healthy adults > 15 years after a simple FS. Methods: Eight healthy subjects (5 men) with a history of simple FS (FS+ group) and eight sex‐ and aged‐matched control subjects (FS– group) were investigated by three MR methods: blinded visual inspection of the MRI pictures; automatic voxel‐based volumetry; and T2 relaxation time measurements. Results: The mean total volume of the two hippocampi was 5.36 ± 1.33 cm 3 in the FS+ group and 6.63 ± 1.46 cm 3 in the FS– group (p = 0.069). The T2 values in the anterior part of the left hippocampus (p = 0.036) and in the middle part of the right hippocampus (p = 0.025) were elevated in the FS+ subjects. The mean volume of the right hippocampus was 3.05 ± 0.8 cm 3 in the FS+ men and 4.05 ± 0.48 cm 3 in the FS– men (p = 0.043). The mean total volume of the two hippocampi was 5.38 ± 1.4 cm 3 in the FS+ men and 7.48 ± 1.14 cm 3 in the FS– men (p = 0.043). There were three FS+ men in whom hippocampal abnormalities including hippocampal sclerosis (HS) and dysgenesis were observed on visual inspection. Conclusions: A history of simple FS in childhood can be associated with hippocampal abnormalities in adults. These abnormalities are probably more pronounced in men. Simple FS may not be as a benign event as previously thought. Our findings suggest that hippocampal abnormalities associated with FS are not necessarily epileptogenic.