Subacute combined degeneration of the cord

Subacute combined degeneration of the cord (SCD) is caused by a vitamin B12 deficiency.

Most common in patients older than 40 and especially older than 60 7

The clinical presentation of SCD is usually paresthesia in the hands and feet, with progression to sensory loss, gait ataxia, and distal weakness, especially in the legs.

In the developed world where nutrition is good, it tends to result most commonly from pernicious anaemia. Other possible causes include Crohn disease and other causes of terminal ileitis. Strict vegetarians or those who are undernourished may develop sufficient deficiencies to develop SCD. SCD can be initiated and exacerbated in these groups by nitrous oxide anaesthesia and abusers of nitrous oxide have also been reported to develop SCD 3

Most commonly there is symmetric bilateral high signal within the dorsal columns. This appearance has been described as the "inverted V sign" 4. The signal changes typically begin in the upper thoracic region, with ascending or descending progression 5. The lateral corticospinal tracts, and sometimes lateral spinothalamic tract may also be involved. Although very unusual, there has been at least one described case of anterior cord involvement 6. Usually these areas have no contrast enhancement. Often there is also accompanying cerebral white matter change. Both spinal and cerebral changes resolve after correction of vitamin B12 deficiency.

  • diagnosis may be confirmed by serum vitamin B12 levels, or holotranscobalamin levels (more sensitive and specific)
  • patient may need to be evaluated for pernicious anaemia
  • cease nitrous oxide inhalation (if applicable)
  • therapy is vitamin B12 replacement
  • approximately half will completely recover 7

Clinical differential diagnosis can be broad.

On imaging the differential includes:

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Article information

rID: 2116
Synonyms or Alternate Spellings:
  • Subacute combined degeneration of the cord
  • Sub acute combined degeneration (SCD)
  • Subacute combined degeneration of the spinal cord

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Cases and figures

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    Case 8: with lateral cord involvement
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