-Case Reports-

Isolated Prosopagnosia Caused by Damage to the Right Inferior Longitudinal Fasciculus: A Case Report

Harumi Morioka¹, Masaru Yanagihashi¹, Mikito Toda², Takanori Ikeda², Masafumi Mizuno³, Masaaki Hori⁴, Kouhei Kamiya⁴ and Osamu Kano¹

¹Department of Neurology, Toho University Faculty of Medicine, Tokyo, Japan
²Department of Cardiology, Toho University Faculty of Medicine, Tokyo, Japan
³Tokyo Metropolitan Matsuzawa Hospital, Tokyo, Japan
⁴Department of Radiology, Toho University Faculty of Medicine, Tokyo, Japan

Prosopagnosia is a cognitive disorder in which facial recognition is severely impaired despite normal vision and intelligence. Prosopagnosia was first reported in the 1800s, but its cause remains unclear. Although other neurological symptoms are often present, some patients have pure prosopagnosia. The bilateral occipital lobes are believed to be associated with symptoms. Recent brain imaging techniques have identified the right fusiform gyrus (rFG), located at the junction of the right occipital temporal lobe, as the affected region. In this report, we present a case of associative prosopagnosia with no concomitant symptoms in a 76-year-old man. Brain magnetic resonance imaging detected a subcortical hemorrhage in the right temporal lobe. Using tractography based on diffusion tensor imaging, we visualized atrophy of the right inferior longitudinal fasciculus (ILF). This is the first time tractography has been used to show a clear association between associative prosopagnosia and ILF damage projecting from the rFG.

J Nippon Med Sch 2025; 92: 220-224

Keywords
prosopagnosia, face recognition, right fusiform gyrus, inferior longitudinal fasciculus

Correspondence to
Harumi Morioka, MD, Department of Neurology, Toho University Faculty of Medicine, 6-11-1 Omorinishi, Ota-ku, Tokyo 143-8541, Japan
harumi.morioka@med.toho-u.ac.jp

Received, July 19, 2023
Accepted, February 9, 2024