オリエンティア・ツツガムシによる神経感染症（つつが虫病）の画像所見：南インドのコホート研究

Scrub typhus is an endemic zoonosis caused by Orientia tsutsugamushi, presenting with a range of neurological manifestations. Despite its high prevalence in endemic areas and clinical relevance, a systematic description of the neuroimaging patterns remains sparse. This study emphasizes the imaging spectrum with clinic-radiological correlations of neurological manifestations of scrub typhus across three tertiary care centers in South India.

This retrospective multicenter study included 55 patients with neurological symptoms and serologically confirmed scrub typhus, who underwent MRI between January 2020 and March 2025. Two experienced neuroradiologists reviewed the imaging for patterns, along with available CT imaging. Detailed demographic, clinical, and laboratory data were studied from health records.

MRI abnormalities were found in 46 of the 55 patients (83.6%). Leptomeningeal enhancement was the most common observation (49.1%), primarily affecting the parieto-occipital and cerebellar sulci, and was best appreciated on post-contrast FLAIR. Encephalitic changes were seen in 16.4% with heterogeneous patterns including cortical, basal ganglia, thalamic, hippocampal, ADEM-like, and ANE-like involvement. 12.7% had cerebellitis, 9.1% had multifocal restricted diffusion, 7.3% had white matter hyperintensities, 7.3% had rhombencephalitis, and 5.5% had myelitis. Lacunar/cerebellar infarcts (5.5%), cerebral venous thrombosis (3.6%), and micro haemorrhages (9.1%) were among the vascular manifestations. Cranial nerves were involved in 5.5%. 20/28 patients (71.4%) had CT abnormalities, with diffuse cerebral edema being the most prevalent. Leptomeningeal enhancement frequently occurred with encephalitis and cerebellitis, while myelitis occurred with rhombencephalitis. ASL was performed in 6 patients, demonstrating hyperperfusion in cases of encephalitis and cerebellitis. Follow-up imaging in 7 patients revealed complete resolution of leptomeningeal and cerebellar enhancement, with variable evolution of encephalopathic changes, ranging from complete resolution to gliosis and volume loss.

Scrub typhus neuroinfection demonstrates a broad imaging spectrum, most frequently leptomeningeal enhancement with characteristic parieto-occipital and cerebellar predilection. MRI remains the modality of choice, though CT retains diagnostic value in acute or resource-limited settings. Recognition of these patterns in febrile patients from endemic regions can expedite diagnosis and treatment, preventing neurological sequelae.