Conclusions
Vitamin B12 is a water soluble substance critical for normal functioning of the nervous system and
blood cell formation. Vitamin B12 deficiency may result from pernicious anemia, gastric resection,
intestinal malabsorption or a strict vegan diet.
It is often overlooked and may cause several hematological, gastrointestinal, psychiatric and
neurological manifestations. Megaloblastic anemia is an early hematological sign, but neurological
symptoms may occur also in the absence of hematological abnormalities. SCD, peripheral neuropathy,
neuropsychiatric disorders and optic nerve atrophy are the most common neurologic manifestations.
The typical MRI finding in SCD is a symmetrical abnormally increased T2 signal intensity, commonly
confined to posterior or posterior and lateral columns in the cervical and thoracic spinal cord. Brain
involvement has also been reported in B12 deficiency patients with extensive areas of a high-intensity
signal in the periventricular white matter.
Physicians should be alert to identifying signs or symptoms of anemia or suspected vitamin
deficiency in populations at risk, even in the absence of hematological symptoms or signs. The
concentration of serum vitamin B12 is not sufficient for diagnosis, and the metabolites upstream
(homocysteine and MMA) should always be looked for. When B12 deficiency is diagnosed, an
extensive search of the cause of cobalamin deficiency should always be carried out.
Parenteral replacement therapy should be initiated as soon as possible and associated with a careful,
life-long, follow-up of the patients. Early diagnosis is crucial for starting replacement therapy and
avoiding irreversible neurological damage.