{'fraction_non_alphanumeric': 0.024071526822558458, 'fraction_numerical': 0.004814305364511692, 'mean_word_length': 5.583710407239819, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Right homonymous hemianopsia following allogenic haematopoietic stem cell transplantation

A 16-yr-old boy with a history of allogenic haematopoietic stem cell transplantation (HSCT) from an unrelated donor for acute T lymphoblastic leukaemia at age 12 presented with acute-onset painless bilateral loss of right field vision. Visual fields showed a right homonymous hemianoptic defect with no macular sparing. Magnetic resonance imaging (MRI) of the left optic tract revealed hyperintense signals (Fig. 1A and B). No leukaemic relapse was identified in the central nervous system (CNS) or bone marrow. Cerebrospinal myelin basic protein levels were elevated with no oligoclonal bands. Serological autoantibodies were negative. Intravenous methylprednisolone treatment showed significant improvement on MRI. Four weeks later, acute blurring of vision recurred and MRI revealed exacerbation extending from the chiasm to bilateral optic tracts (Fig. 1C and D). Repeated intravenous methylprednisolone and immune globulin brought rapid recovery of visual acuity and MRI findings. Following oral dexamethasone and cyclosporine A treatment, no recurrence was observed on MRI in follow-up at 8 months. Homonymous hemianopsia occurs frequently in stroke and traumatic brain injuries. In this case, although the underlying mechanisms remain unclear, a post-HSCT autoimmunity mechanism similar to multiple sclerosis or CNS graft-versus-host disease was suspected.