Subacute combined degeneration is a disorder of the spine, brain, and nerves. It involves
Subacute combined degeneration of the spinal cord; SCD
Subacute combined degeneration is caused by a vitamin B12 deficiency. It mainly affects the spinal cord. But its effects on the brain and the peripheral (body) nerves are the reason for use of the term “combined.” At first, the covering of the nerves (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 the lack of this vitamin causes abnormal fatty acids to form around cells and nerves.
A person has a high risk of this condition if vitamin B12 cannot be absorbed from the intestine or if a person has:
- Disorders of the small intestine, including
- Problems absorbing nutrients, which can occur after gastrointestinal surgery
Abnormal sensations (
Weakness of the legs, arms, or other areas
These symptoms slowly get worse and are usually felt on both sides of the body.
Other symptoms include:
Clumsiness, stiff, or awkward movements Change in mental statesuch as memory problems, irritability, apathy, confusion, or dementia Decreased vision Depression
Unsteady gaitand loss of balance
Exams and Tests
The health care provider will perform a physical exam. The exam usually shows
Mental changes range from mild forgetfulness to severe dementia or
An eye exam may show damage to the optic nerve, a condition called
Blood teststhat may be ordered include:
Early treatment improves the chance of a good outcome.
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.
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 iss delayed for longer than 1 or 2 months, full recovery may not be possible.
Untreated, the disorder results in progressive and irreversible damage to the nervous system.
Complications can include permanent, progressive loss of nerve and mental functions.
When to Contact a Medical Professional
Call your health care provider if abnormal sensations, muscle weakness, or other symptoms of subacute combined degeneration develop. This is particularly important if you or a family member has had pernicious anemia or other risk factors.
Some vegetarian diets may be low in vitamin B12. Taking a supplement can prevent the disorder.