Objective:

To present a case of late-onset neurotoxicity following CAR-T therapy and review similar instances of immune effector cell-associated nerve palsies.

Approach:

• Case Presentation: A patient with refractory multiple myeloma developed diplopia, bilateral upward gaze limitation, abducens palsy, bilateral facial nerve palsy, and thoracic sensory radiculopathy post-CAR-T therapy, suspected to be delayed immune effector cell-associated nerve palsies (IEC-NPs).
• Treatment Regimen: The patient was treated with intrathecal methotrexate and systemic cyclophosphamide after steroid resistance, leading to acute symptomatic improvement.

Key Findings:

• The patient exhibited diplopia, bilateral upward gaze limitation, abducens palsy, bilateral facial nerve palsy, and thoracic sensory radiculopathy after CAR-T therapy.
• Symptoms progressed despite steroid treatment, indicating steroid-resistant IEC-NPs.
• Intrathecal methotrexate and systemic cyclophosphamide resulted in acute symptomatic improvement.

Interpretation:

This case contributes to the understanding of IEC-NPs and highlights treatment options for steroid-resistant cases.

Limitations:

• The case is a single patient report, limiting generalizability to broader populations.
• Long-term outcomes and potential recurrence of symptoms were not addressed in this report.

Conclusion:

The case illustrates the complexity of managing late-onset neurotoxicities following CAR-T therapy and suggests alternative treatment strategies for resistant cases.