Supplementary Material for: Radiation Myelopathy Caused by Palliative Radiotherapy and Intrathecal Methotrexate

Radiation myelopathy is a rare, late-stage adverse event that develops following irradiation at or above 50 Gy. Here, we report a case of irreversible paraplegia caused by palliative radiation (20 Gy in 5 fractions) to the spinal cord combined with intrathecal methotrexate (IT-MTX). A 69-year-old man presented with back pain, prompting a diagnosis of acute myeloid leukemia. At the first visit, he complained of muscle weakness and hypoesthesia in both legs; spinal magnetic resonance imaging (MRI) revealed an epidural mass compressing the spinal cord at the fifth to seventh level of the thoracic vertebrae. This was considered to be an extramedullary lesion of leukemia, and he received remission induction therapy including IT-MTX; palliative radiation (20 Gy in 5 fractions) of the epidural mass was initiated the following day. Then, during the course of consolidation therapy, a second IT-MTX was performed after 1 month and a third after 3 months. While the consolidation therapy was complete, yielding remission, he developed sudden paraplegia, as well as bladder and bowel dysfunction (BBD), 10 months later. Spinal MRI showed extensive intramedullary high signal intensity on T2-weighted image, including the irradiation field. It was thought myelopathy was due to irradiation of the spinal cord combined with IT-MTX. He immediately received steroid pulse therapy; however, the paraplegia and BBD did not improve. It is extremely rare for irreversible radiation myelopathy to occur with IT-MTX and palliative radiation to the spinal cord. We believe that even with low-dose palliative radiation, caution is required for combined use with IT-MTX.

放射性脊髓病（Radiation myelopathy）是一类罕见的迟发性不良反应，常发生于接受50 Gy及以上剂量电离辐射照射后。本文报告1例因脊髓姑息性放疗（5分割20 Gy）联合鞘内注射甲氨蝶呤（intrathecal methotrexate, IT-MTX）引发不可逆截瘫的临床病例。患者为69岁男性，因背痛就诊，最终确诊为急性髓系白血病。初诊时，患者主诉双下肢肌力减退与感觉减退；脊柱磁共振成像（spinal magnetic resonance imaging, MRI）显示胸椎5~7节段存在硬膜外肿块，压迫脊髓。该病变被判定为白血病髓外病变，患者随即接受了包含鞘内注射甲氨蝶呤在内的诱导缓解治疗；次日即启动针对该硬膜外肿块的姑息性放疗（5分割20 Gy）。在巩固治疗阶段，患者分别于治疗后1个月及第3个月接受了第二次及第三次鞘内注射甲氨蝶呤。尽管巩固治疗顺利完成并使患者获得疾病缓解，但在治疗结束10个月后，患者突发截瘫及二便功能障碍（bladder and bowel dysfunction, BBD）。脊柱MRI检查显示，照射野范围内的T2加权像可见广泛髓内高信号。临床考虑该脊髓病为脊髓照射联合鞘内注射甲氨蝶呤所致。患者随即接受类固醇冲击治疗，但截瘫及二便功能障碍未获改善。脊髓姑息性放疗联合鞘内注射甲氨蝶呤引发不可逆放射性脊髓病的病例极为罕见。我们认为，即便采用低剂量姑息性放疗，与鞘内注射甲氨蝶呤联用时仍需严加警惕。