Post-thalamotomy Changes Mimicking Cavernous Malformations on MRI: A Case Report of a Historical Surgical Treatment.

The patient was a 65-year-old man with cervical dystonia onset at age six who had been treated at Chiba University Hospital. He was diagnosed and followed up with cavernous malformations and chronic cerebral infarctions based on an MRI. However, during the re-evaluation of MRI, lesions with low signal intensity (SI) cores surrounded by high SI rims were observed in bilateral thalami and left subthalamic nucleus on T2-weighted images, which differed from typical cavernous malformations. In addition, symmetrical scarring changes were noted in the frontal lobes and bilateral parietal bones, potentially corresponding to the thalamic and subthalamic nucleus lesions. Upon reviewing medical history, it was revealed that the patient had undergone thalamotomy in 1963 and 1964. The literature review suggested the use of procaine-oil blocking during thalamotomies of that era. Chemical shift imaging was added, and the presence of fat was confirmed in bilateral thalamic lesions with high SI on in-phase and low SI on out-of-phase images. Imaging findings resulting from obsolete treatments can be unfamiliar and mistaken for pathological conditions. Investigating the history of suspected treatments can lead to definitive diagnoses through imaging studies.