SUBACUTE COMBINED DEGENERATION

Vitamin B12 Deficiency

Subacute Combined Degeneration (SCD) is a neurological manifestation of Vitamin B12 (cobalamin) deficiency. “Subacute” refers to its slow onset. “Combined Degeneration” refers to how both the dorsal columns and the lateral corticospinal tracts are damaged

Folate deficiency and B12 deficiency both cause macrocytic anemia. We can tell them apart because B12 deficiency causes neurological symptoms while folate does not. SCD is often that neurological symptom. 

What are the most common causes of B12 deficiency?

Pernicious anemia is an autoimmune attack on parietal cells in the stomach. They produce intrinsic factor, which is needed to absorb B12. 

B12 is exclusively found in animal protein, so vegans can get SCD, but only after several years sans supplements (there are big B12 stores in the liver). 

Symptoms?

Spinocerebellar tract damage → ataxia

Corticospinal tract damage → spastic paralysis

Dorsal column damage → vibrational numbness

Treatment?

B12 supplements duh. Most of the symptoms are actually reversible with treatment, huzzah!