Punctate Hippocampal Hyperintensities on Diffusion-Weighted Imaging Following Epileptic Seizures: A Case Report.

Punctate hippocampal hyperintensity (PHH) on diffusion-weighted imaging (DWI) is a well-known observation in patients with transient global amnesia (TGA), which is characterized by acute self-limiting episodes of anterograde and retrograde amnesia. These lesions occur unilaterally or bilaterally in the CA1 regions of the hippocampus, which are crucial for memory processes. PHH on DWI is well-documented in TGA but rare in other conditions. This case report describes a 56-year-old male bus driver who presented with PHH on DWI following epileptic seizures without TGA-like episodes. The patient experienced mild dizziness initially and subsequently lost consciousness while cleaning a bus. He was found collapsed outside the bus. The patient was slightly obtunded on arrival at the hospital and fully alert after admission. DWI showed bilateral PHHs in the CA1 regions. Recordings from multiple drive cameras installed on the bus clarified that he had developed gyratory seizures to the right, followed by focal onset bilateral tonic-clonic seizures. A seizure arising from the left hemisphere was suspected. As this was his first unprovoked seizure, the patient was closely followed up. This case demonstrates that PHH, a representative imaging feature of TGA, appeared with epileptic events but without TGA-like episodes. The occurrence of PHH in this context may broaden the clinical significance of PHH, with such occurrences helping to clarify the mechanisms underlying this condition.