An 80-year-old man was admitted for subacute gait disturbance. His bilateral lower limb impairment had developed over 2 weeks. A general physical examination was normal. Neurological examination revealed muscle weakness of grade 4/5 affecting both lower limbs. Deep tendon reflexes were absent in both limbs without pathological reflexes. There was loss of deep sensation below T10. He had bladder and rectal disturbance. His EDSS score was 8.5. Findings from routine serum and CSF studies were normal. Spinal MRI on T2WI revealed high signals extending from Th9 to Th12 in the central part of the cord (Fig. ). The lesions showed no contrast enhancement. Brain MRI showed no abnormality. As autoimmune myelitis was suspected, he received high-dose methylprednisolone (1,000 mg/day for 3 days, 2 courses). His serum was positive for anti-AQP4 antibody on the 15th day of his hospitalization. He was diagnosed with NMOSD and treated with immunoadsorption plasmapheresis and followed up with daily prednisolone (30 mg). The muscle strength of the lower limb slightly improved; however, he was bedridden, and the paraplegia persisted. Repeat MRI showed marked regression of thoracic lesions on the 43rd day of his hospitalization. He was discharged to another hospital for rehabilitation 50 days after his hospitalization with daily prednisolone (10 mg). His EDSS score was 7.5.
An 88-year-old woman experienced numbness in her legs and moderate paraparesis with impaired gait since 2 days. Spinal MRI demonstrated a myelon lesion from vertebra T6-9 (Fig. b-c), which was initially attributed to compression myelopathy because of concomitant vertebral disc protrusions. Without specific treatment, she recovered partially and was able to walk with a crutch for >100 m (EDSS 6.0). Her previous medical history was negative for prior potential attacks, but included a transient ischemic attack with dysarthria for <24 h 1.5 years before; cerebral MRI had not shown inflammatory lesions.\nEight months later, she was re-admitted with an anew gait impairment and sensorimotor paraparesis (MRC grade 2–3, EDSS 8.5). MRI demonstrated a new T2 hyperintense myelon lesion from vertebra T10–T12 with central gadolinium enhancement (Fig. d–f). Visual evoked potentials had low amplitudes bilaterally and normal latencies. CSF showed mild lymphomonocytic pleocytosis and positive OCB. Serum AQP4-Ab were positive (1:3200, cell-based immunofluorescence assay), as were antibodies against dsDNA and cardiolipin. Diagnosis of AQP4-Ab positive NMOSD was established, and the first myelon lesion was retrospectively attributed also to NMOSD. Treatment included methylprednisolone 5 × 1 g, a second cycle of 5 × 2 g, and then plasma exchange. She recovered partially (EDSS 7.0). Azathioprine was given up to 150 mg/d (2.2 mg/kg); thiopurine S-methyltransferase activity was normal. After 5 months of therapy, regular blood testing revealed pancytopenia. Azathioprine was stopped, but thrombocytopenia persisted and she died of intestinal bleeding. In addition to azathioprine as a likely cause for bone marrow suppression and thrombocytopenia, she had also developed anti-platelet antibodies.