1 - Department of Neuroradiology, Centro Hospitalar e Universitário de Lisboa Central (CHULC), Lisbon, Portugal
- XVIII congresso SPNR - 16 a 18 Novembro 2023, Braga
INTRODUCTION: The hippocampus is one of the most metabolically demanding areas of the brain and therefore more vulnerable to several types of acute brain injury. Excitotoxic brain injury represents the common final pathway of acute ischemic, infectious, inflammatory, toxic, metabolic and miscellaneous lesions and its damage may be assessed by diffusion-weighted imaging (DWI) MRI. Compared to other areas of the brain, the hippocampus also shows a higher density of glutamate receptors, which are known to be involved in the excitotoxic damage pathway. Therefore, the purpose of this work is to present a pictorial essay of cytotoxic lesions of several etiologies involving the hippocampus.
MATERIAL AND METHODS: Our prospective database was screened and patients with hippocampal lesions presenting with restricted diffusion on DWI sequences were selected.
RESULTS: We present 9 illustrative cases of lesions involving the hippocampus and presenting with restricted diffusion. These cases are secondary to acute hypoxia/ischemia (two), infectious lesions (two), toxic injury caused by drugs (one), iatrogenic post-surgical injury (one), metabolic injury (one) and the remaining 2 can be considered miscellaneous in etiology. Acute ischemic lesions include acute stroke caused by posterior cerebral artery occlusion and acute hypoxic-ischemic injury following cardiac arrest. Infectious lesions comprise herpes simplex encephalitis and acute necrotizing encephalitis. Toxic injury is represented in a case of vigabatrin toxicity, early post-surgical tissue injury is demonstrated following tumor resection and metabolic injury is shown in a case of Mitochondrial Encephalopathy, Lactic Acidosis and Stroke-like episodes (MELAS). Miscellaneous etiology includes cases of status epilepticus and transient global amnesia.
CONCLUSION: The differential diagnosis of hippocampal lesions presenting with restricted diffusion is broad and often not pathognomonic. Taking into account the patients’ medical history, laboratorial analysis results and additional imaging features may be helpful in finding the correct final diagnosis, providing appropriate treatment and establishing each patient’s prognosis.
Keywords: Hippocampus; DWI; Differential diagnosis; MRI