Subacute combined degeneration of spinal cord
| Subacute combined degeneration of spinal cord | |
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| Diagram of the principal fasciculi of the spinal cord. (In subacute combined degeneration of spinal cord, the "combined" refers to the fact that the dorsal columns and lateral corticospinal tracts are both affected, in contrast to tabes dorsalis which is selective for the dorsal columns.) | |
| Classification and external resources | |
| Specialty | endocrinology |
| ICD-10 | G32.0, E53.8 |
| ICD-9-CM | 336.2, 266.2 |
| DiseasesDB | 12591 |
| MedlinePlus | 000723 |
| MeSH | D052879 |
Subacute combined degeneration of spinal cord, also known as Lichtheim's disease, refers to degeneration of the posterior and lateral columns of the spinal cord as a result of vitamin B12 deficiency (most common), vitamin E deficiency, and copper deficiency. It is usually associated with pernicious anemia.
This condition can be due to a dietary deficiency of B12, malabsorption of B12 in the terminal ileum, lack of intrinsic factor secreted from gastric parietal cells, low gastric pH inhibiting attachment of intrinsic factor to ileal receptors.
Vitamin E deficiency, which is associated with malabsorption disorders such as cystic fibrosis and Bassen-Kornzweig syndrome, can cause a similar presentation due to the degeneration of the dorsal columns.
The onset is gradual and uniform. The pathological findings of subacute combined degeneration consist of patchy losses of myelin in the dorsal and lateral columns. Patients present with weakness of legs, arms, trunk, tingling and numbness that progressively worsens. Vision changes and change of mental state may also be present. Bilateral spastic paresis may develop and pressure, vibration and touch sense are diminished. A positive Babinski sign may be seen. Prolonged deficiency of vitamin B12 leads to irreversible nervous system damage. HIV-associated vacuolar myelopathy can present with a similar pattern of dorsal column and corticospinal tract demyelination.
It has been thought that if someone is deficient in vitamin B12 and folic acid, the vitamin B12 deficiency must be treated first. However, modern research says ″Although it was thought that folic acid might exacerbate vitamin B12 deficiency and its symptoms, it is probably not the case″. And that if this were the case then ″mechanisms by which folic acid exacerbates vitamin B12 deficiency remain unclear″
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