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Vitamin B12-responsive severe leukoencephalopathy and autonomic dysfunction in a patient with “normal” serum B12 levels
  1. J J Graber1,
  2. F T Sherman2,
  3. H Kaufmann3,
  4. E H Kolodny4,
  5. S Sathe4
  1. 1Department of Neuro-oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
  2. 2Department of Geriatrics and Adult Development and Medicine, Mount Sinai School of Medicine, New York, New York, USA
  3. 3New York University School of Medicine, New York, New York, USA
  4. 4Division of Neurogenetics, Department of Neurology, New York University School of Medicine, New York, New York, USA
  1. Correspondence to Dr Swati Sathe, Division of Neurogenetics, Department of Neurology, 403 E 34th St 2nd floor, New York NY 10016, USA; swati.sathe{at}


Leukoencephalopathy and autonomic dysfunction have been described in individuals with very low serum B12 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 B12 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 B12 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 B12 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 B12, homocysteine and methylmalonic acid levels are unreliable predictors of B12-responsive neurologic disorders, and should be thoroughly investigated and presumptively treated in patients with unexplained leukoencephalopathy because even long-standing deficits may be reversible.

  • Amnesia
  • autonomic
  • B12 deficiency
  • cognition
  • dementia

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  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.