-Case Reports-

Formation of a Large Fusiform Aneurysm near a Medullary Infarction Caused by Dissection of the Posterior Inferior Cerebellar Artery

Masahiro Yamaguchi¹, Kyongsong Kim¹, Takayuki Mizunari¹, Katsuya Umeoka¹, Kenta Koketsu¹, Koshiro Isayama² and Akio Morita²

¹Department of Neurological Surgery, Nippon Medical School Chiba Hokusoh Hospital, Chiba, Japan
²Department of Neurological Surgery, Nippon Medical School Hospital, Tokyo, Japan

Infarction of the posterior inferior cerebellar artery (PICA) can lead to ischemic stroke in the lateral medullary oblongata. PICA dissection can also elicit an ischemic event in this region, but its detection on radiological images is difficult because of the small diameter of the vessel. We report a case of Wallenberg syndrome due to PICA dissection in a 48-year-old man, which was difficult to diagnose on first admission. He reported sudden onset of sensory disturbance on the right side of his face, ataxic gait, and headache. Brain magnetic resonance imaging (MRI) revealed a fresh cerebral infarct in the right lateral medulla oblongata. Magnetic resonance angiography (MRA) performed at the time of his admission showed no cerebral vessel abnormalities. An MRI study 18 months after the event revealed a fusiform aneurysm on the lateral medullary segment of the PICA, which was extremely close to the cerebral infarct. We concluded that the infarct was due to PICA dissection because of the sudden onset of symptoms and because the infarcted territory of the occluded penetrating branch of the dissecting aneurysm was consistent with Wallenberg syndrome. The aneurysm was trapped and an occipital artery-PICA bypass was placed. At the latest follow-up, 1 year after the procedure, he had no neurological symptoms. Imaging findings at the time of his first admission indicated that the PICA was intact. However, 18 months later, MRI revealed enlargement of an aneurysm at the site of the dissection. A cerebral infarct with headache may indicate PICA dissection.

J Nippon Med Sch 2024; 91: 129-133

Keywords
posterior inferior cerebellar artery, arterial dissection, cerebral infarction, large aneurysm, occipital artery-posterior inferior cerebellar artery bypass

Correspondence to
Masahiro Yamaguchi, MD, PhD, Department of Neurological Surgery, Nippon Medical School Chiba Hokusoh Hospital, 1715 Kamagari, Inzai, Chiba 270-1694, Japan
maaasa@nms.ac.jp

Received, September 15, 2022
Accepted, December 2, 2022