We present a unique case of a 61-year-old female with metastatic uveal melanoma with recurrent longitudinally extensive transverse myelitis affecting the entire spinal cord after treatment with combination ipilimumab (anti-CTLA-4) and nivolumab (anti-PD-1) immune checkpoint inhibitors. She developed subacute ascending lower extremity parasthesias up to her knees, lower extremity weakness, and ataxia with exam notable for mild diffuse weakness, diminished sensation to all modalities in the lower extremities with a mid-thoracic sensory level, diffuse hyperreflexia, dysmetria, and a wide based ataxic gait. 

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MRI neuro-axis revealed diffuse enhancement and T2 hyperintense signal extending from the cervicomedullary junction down to the conus medullaris. Serum inflammatory, autoimmune, and infectious workup were unremarkable. CSF studies revealed lymphocytic predominant pleocytosis WBC 75 (91 lymphocytes, 9 monocytes), glucose 42, and elevated protein of 125. CSF infectious, autoimmune, and neoplastic workup was negative.

She received intravenous methylprednisolone 1000mg daily for 5 days followed by an oral prednisone starting at 60mg (1mg/kg) with a 10mg/week taper. Her symptoms fully resolved with follow-up MRI showing complete resolution. Several weeks after finishing the prednisone taper, she presented with ataxia with repeat radiographic, serum and CSF showing similar findings as before. She was again treated with IV methylprednisolone 1000mg for 5 days followed by longer oral prednisone taper over 4 months. Repeat lumbar puncture prior to discontinuing steroids showed no pleocytosis. Since weaning off steroids, she has had no further neurologic issues. 

Immune checkpoint inhibitors are increasingly being used and studied in many cancer types. Neurologists must be aware of the diverse neurologic toxicities related to checkpoint inhibitors including inflammatory demyelinating polyneuropathy, peripheral neuropathies, meningo-radiculoneuritis, encephalitis, myositis and myasthenia gravis. Here we describe a longitudinally extensive transverse myelitis affecting the entire spinal cord after exposure to ipilimumab and nivolumab with excellent and durable response to corticosteroids.