Steroid-resistant bilateral facial nerve palsies, ophthalmoparesis, and multilevel thoracic radiculopathy as immune effector cell-associated late-onset neurotoxicity after cilta-cel CAR-T therapy: a case report and review of similar cases.

The use of chimeric antigen receptor T-cell (CAR-T) therapy has become more widespread in recent years, most commonly for hematologic malignancies. This therapy can be potentially associated with neurotoxic side effects. We present a patient with refractory multiple myeloma who developed diplopia, bilateral upward gaze limitation, abducens palsy, bilateral facial nerve palsy, and thoracic sensory radiculopathy following a course of CAR-T therapy, which were suspected to represent delayed immune effector cell-associated nerve palsies (IEC-NPs). His symptoms progressed despite oral and intravenous steroids. Subsequent intrathecal methotrexate and systemic cyclophosphamide resulted in acute symptomatic improvement and eventual resolution of diplopia and gradual recovery of extraocular movements and facial nerve palsies.