Evolving Magnetic Resonance Imaging (MRI) Findings in Immune Effector Cell-Associated Neurotoxicity Syndrome.

Immune effector cell-associated neurotoxicity syndrome (ICANS) is a potentially life-threatening complication often observed in patients receiving immunotherapies like chimeric antigen receptor T-cell (CAR-T) therapy. This case report is based on a chart review of the history, physical examination of the primary team, laboratory tests, imaging findings, and discharge summary of the patient's hospital admission and subsequent encounters. We present the case of a middle-aged man with multiple myeloma who developed ICANS following two cycles of talquetamab (Talvey) therapy. The patient's initial symptoms included fever and altered mental status. Magnetic resonance imaging (MRI) revealed a multitude of foci, including T1 enhancement of the hypothalamus and caudate heads, fluid-attenuated inversion recovery (FLAIR) hyperintensities of the caudate nuclei and subependymal regions, susceptibility artifacts in the lentiform nuclei, and diffusion restriction in the corpus callosum. Altered mental status, fever, and elevations in cerebrospinal protein raised concern for possible neurotoxicity, and the patient was treated with steroids and tocilizumab. A follow-up MRI taken 24 days later demonstrated a progression of signal abnormalities in the caudate nuclei and a new rim of susceptibility in the bilateral caudate heads. A third MRI was performed 99 days after the original MRI, which tracked the resolution of the diffusion restriction and FLAIR abnormalities, but noted further increased susceptibility artifacts and new peripherally enhancing lesions in the bilateral caudate heads. A final MRI taken 250 days after the initial MRI tracked the resolution of the caudate lesions, with stable susceptibility artifacts. This case highlights the evolving nature of ICANS and underscores the role of serial MRI in tracking neurotoxicity progression, guiding treatment, and improving outcomes in immunotherapy-related complications.