Neurologic Manifestations of Vitamin B12 Deficiency

In our discussion this morning about the causes of “fall and dementia” we briefly touched on Vitamin B12 deficiently. Vitamin B12 is a water soluble present in animal products (meat and dairy). B12 is involved in myelin synthesis, and hence, it’s deficiency has neurologic consequences.

Neurologic manifestations of B12 deficiency is the classic subacute combined degeneration of the dorsal (posterior) and lateral spinal columns. SCD manifests as symmetrical primarily lower limb neuropathy with loss of vibration and position sense, which can result in ataxia.

Other neurologic findings in B12 deficiency include axonal degeneration of peripheral nerves and central nervous system symptoms including memory loss, irritability, and dementia.

Interestingly, not all patients with neurologic abnormalities secondary to Vit B12 deficiency have hematologic manifestations.

Here is good review of B12 deficiency.
Current concepts in the diagnosis of cobalamin deficiency. Green R, Kinsella LJ. Neurology. 1995;45(8):1435.

*the picture is an axial image of the spinal cord of a patient with B12 Deficiency. Blue is where myeline is stained and you can see the loss of myeline latterally and posteriorly.