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41 y.o. vegan with “tingling in her feet.”

Findings

Sagittal T2-weighted image demonstrates a long segment of high signal intensity within the dorsal aspect of the cervical spinal cord.

Axial T2-weighted image shows high signal intensity within the dorsal columns.

No enhancement.

Conditions ass. w/ Degeneration of the Posterior Columns

Subacute Combined Degeneration

Folic Acid deficiency

Multiple sclerosis

Trauma

Tumor

Tabes dorsalis

Toxic insult (Thallium and Vincristine)

Vacuolar myelopathy

Conditions ass. w/ Degeneration of the Posterior Columns

Subacute Combined Degeneration

Folic Acid deficiency

Multiple sclerosis

Trauma

Tumor

Tabes dorsalis

Toxic insult (Thallium and Vincristine)

Vacuolar myelopathy

Subacute combined degeneration (SCD)

Vitamin B12 (cobalamin) deficiency may affect the CNS or peripheral nervous system but most commonly involves the spinal cord.

In the USA, the most common cause of B12 deficiency is pernicious anemia 2° auto-immune gastritis in which intrinsic factor is not produced.

Other causes: gastric surgery, malabsorption syndromes, and dietary deficiencies.

Symptoms: generalized weakness, paresthesias involving the hands and feet, unsteady gait, limb weakness, and stiffness. If untreated may evolve to ataxic paraplegia with spasticity and contractures.

Subacute combined degeneration (SCD)

Clinical signs: loss of proprio-reception and loss of vibration (most pronounced in the legs).

SCD is primarily a myelinopathy, but axonal degeneration is always seen in long-standing cases. The brain appears macroscopically normal, but the spinal cord is shrunken.

Grossly, the posterior and lateral columns of the spinal cord appear gray-white in color with an almost translucent appearance.

Subacute combined degeneration (SCD)

Early lesions contain swollen myelin sheaths with little change in the axons. Lesions begin as small foci and become confluent. In full-blown cases, the spinal cord has multifocal vacuolated and demyelinated lesions affecting the dorsal and lateral columns (the anterior columns are not exempt).

The mid-thoracic cord is usually the most severely affected.

Small areas of perivascular demyelination may also be found in the brain.

Subacute combined degeneration (SCD)

Findings in the spinal cord include: hyperintensity on T2-weighted sequences in the dorsal columns of the cervical and thoracic cord.

Mild expansion of the cord may be seen and mild contrast enhancement has been described.

There is typically a continuous long segment of signal abnormality confined to the dorsal columns.

Subacute combined degeneration (SCD)

Vacuolar myelopathy seen in patients with AIDS may appear similar on imaging, i.e. clinical history plays an important role.

Imaging findings in SCD may resolve after treatment with vitamin B12.

MR findings in the brain may reveal areas of hyperintensity on the T2-weighted images in the cerebral white matter that may also resolve after treatment with vitamin B12.

Slick?

In the setting of SCD and pernicious anemia (most common cause in the USA), look for hypointense marrow on T1 & T2: benign hyperplasia of the hematopoietic marrow.