Department of Neuro-oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
J Neurol Neurosurg Psychiatry. 2010 Dec;81(12):1369-71. doi: 10.1136/jnnp.2009.178657. Epub 2010 Jun 28.
Leukoencephalopathy and autonomic dysfunction have been described in individuals with very low serum B(12) levels (<200 pg/ml), in addition to psychiatric changes, neuropathy, dementia and subacute combined degeneration. Elevated homocysteine and methylmalonic acid levels are considered more sensitive and specific for evaluating truly functional B(12) deficiency. A previously healthy 62-year-old woman developed depression and cognitive deficits with autonomic dysfunction that progressed over the course of 5 years. The patient had progressive, severe leukoencephalopathy on multiple MRI scans over 5 years. Serum B(12) levels ranged from 267 to 447 pg/ml. Homocysteine and methylmalonic acid levels were normal. Testing for antibody to intrinsic factor was positive, consistent with pernicious anaemia. After treatment with intramuscular B(12) injections (1000 μg daily for 1 week, weekly for 6 weeks, then monthly), she made a remarkable clinical recovery but remained amnesic for major events of the last 5 years. Repeat MRI showed partial resolution of white matter changes. Serum B(12), homocysteine and methylmalonic acid levels are unreliable predictors of B(12)-responsive neurologic disorders, and should be thoroughly investigated and presumptively treated in patients with unexplained leukoencephalopathy because even long-standing deficits may be reversible.
患者为 62 岁既往健康女性，出现抑郁和认知功能障碍伴自主神经功能障碍，且病情逐渐进展，历时 5 年。患者在 5 年期间进行了多次 MRI 扫描，均显示进行性严重的脑白质病变。血清 B12 水平在 267-447pg/ml 之间波动。同型半胱氨酸和甲基丙二酸水平正常。针对内因子抗体的检测呈阳性，提示恶性贫血。给予肌内注射维生素 B12（1000μg/d，连用 1 周，随后每周 1 次，连用 6 周，之后每月 1 次）治疗后，患者的临床症状明显改善，但仍对过去 5 年中的重大事件存在遗忘。重复 MRI 显示脑白质病变部分缓解。血清 B12、同型半胱氨酸和甲基丙二酸水平并不是维生素 B12 反应性神经功能障碍的可靠预测指标，对于不明原因的脑白质病变患者，应进行全面检查并进行经验性治疗，因为即使是长期存在的缺陷也可能是可逆的。
