Chimeric antigen receptor (CAR) T-cell therapy is a cell-based treatment for hematological malignancies, offering potential for clinical remission of refractory disease. Nonetheless, immune-mediated neurotoxicity can occur post-treatment and we present a unique case of a pharyngo-brachial cervical variant of GBS (Guillain-Barre Syndrome) post-CAR T-cell therapy.

74-year-old man with Stage 3A kappa light chain multiple myeloma refractory to autologous stem cell transplant and several lines of treatment received CAR-T cell infusion. A month later, he presented with acute left facial palsy and binocular horizontal diplopia. Exam disclosed bilateral lower CN VII palsy, left CN VI palsy, and right CN X palsy with areflexia. MRI brain showed abnormal enhancement of the canalicular portion of the left 7th cranial nerve. Lumbar puncture demonstrated WBC 9, lymphocytic pleocytosis and mildly elevated protein to 51 with no intrathecal IgG synthesis. EMG/NCS showed sensorimotor length-dependent axonal neuropathy. Due to suspicion for CAR-T related neurotoxicity, he was treated with IVIg for 2 days and IV methylprednisolone followed by steroid taper. Two weeks post-discharge, he developed lower extremity weakness, proximal upper extremity weakness and right wrist drop; repeat LP demonstrated WBC 5 with lymphocytic pleocytosis. MRI spine demonstrated stable bony metastases.  Anti-ganglioside, anti-MAG antibodies, and anti-aquaporin-4 antibodies were negative. Maintenance immunotherapy was initiated with IVIg 1gm/kg every 2 weeks and his cranial palsies resolved and his right wrist drop dramatically improved.

Neurotoxicity in CAR T-cell therapy is heterogeneous in phenotype; PBC variant is a rare variant of GBS characterized by muscle weakness extending from the cervical and oropharyngeal region to the proximal upper extremities with simultaneous areflexia; and may have ophthalmoplegia due to overlap with Miller-Fisher variant of GBS. Some exhibit positive anti-GT1a antibodies and ganglioside antibodies may be negative. This is the first reported case of a PBC variant of GBS post CAR T-cell therapy.