Learn About Subacute Combined Degeneration

What is the definition of Subacute Combined Degeneration?

Subacute combined degeneration (SCD) is a disorder of the spine, brain, and nerves. It involves weakness, abnormal sensations, mental problems, and vision difficulties.

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What are the alternative names for Subacute Combined Degeneration?

Subacute combined degeneration of the spinal cord; SCD

What are the causes of Subacute Combined Degeneration?

SCD is caused by vitamin B12 deficiency. It mainly affects the spinal cord. But its effects on the brain and the peripheral (body) nerves are the reason for the term "combined." At first, the nerve covering (myelin sheath) is damaged. Later, the entire nerve cell is affected.

Doctors do not know exactly how a lack of vitamin B12 damages the nerves. It is possible that the lack of this vitamin causes abnormal fatty acids to form around cells and nerves.

People are at high risk for this condition if vitamin B12 cannot be absorbed from their intestine or if they have:

  • Pernicious anemia, a condition in which the body does not have enough healthy red blood cells
  • Disorders of the small intestine, including Crohn disease
  • Problems absorbing nutrients, which can occur after gastrointestinal surgery
  • Use of nitrous oxide (laughing gas), especially if used as a recreational drug
What are the symptoms of Subacute Combined Degeneration?

Symptoms include:

  • Abnormal sensations (tingling and numbness)
  • Weakness of the legs, arms, or other areas

These symptoms slowly get worse and are usually felt on both sides of the body.

As the disease worsens, symptoms may include any of the following:

  • Clumsiness, stiff or awkward movements
  • Change in mental state, such as memory problems, irritability, apathy, confusion, or dementia
  • Decreased vision
  • Depression
  • Sleepiness
  • Unsteady gait and loss of balance
  • Falls due to poor balance
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What are the current treatments for Subacute Combined Degeneration?

Vitamin B12 is given, usually by injection into a muscle. Injections are often given once a day for a week, then weekly for about 1 month, and then monthly. Vitamin B12 supplements, either by injection or high-dose pills, must continue throughout life to prevent symptoms from returning.

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What is the outlook (prognosis) for Subacute Combined Degeneration?

Early treatment improves the chance of a good outcome.

How well a person does depends on how long they had symptoms before receiving treatment. If treatment is received within a few weeks, complete recovery may be expected. If treatment is delayed for longer than 1 or 2 months, full recovery may not be possible.

Untreated, SCD results in continued and permanent damage to the nervous system.

When should I contact a medical professional for Subacute Combined Degeneration?

Contact your provider if abnormal sensations, muscle weakness, or other symptoms of SCD develop. This is particularly important if you or a family member has had pernicious anemia or other risk factors.

How do I prevent Subacute Combined Degeneration?

Some vegetarian diets, especially vegan, may be low in vitamin B12. Taking a supplement can help prevent SCD.

Central nervous system and peripheral nervous system
Central nervous system
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What are the Latest Advances for Subacute Combined Degeneration?
Megaloblastic wobbliness: A reversible neurological condition.
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Subacute combined degeneration of the spinal cord with concomitant autoimmune disease: report of 2 cases.
Who are the sources who wrote this article ?

Published Date: May 04, 2021
Published By: Joseph V. Campellone, MD, Department of Neurology, Cooper Medical School at Rowan University, Camden, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

What are the references for this article ?

Pytel P, Anthony DC. Peripheral nerves and skeletal muscles. In: Kumar V, Abbas AK, Aster JC, eds. Robbins and Cotran Pathologic Basis of Disease. 10th ed. Philadelphia, PA: Elsevier; 2021:chap 27.

So YT. Deficiency diseases of the nervous system. In: Jankovic J, Mazziotta JC, Pomeroy SL, Newman NJ, eds. Bradley and Daroff's Neurology in Clinical Practice. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 85.