What is Subacute Combined Degeneration of the Spinal Cord (Archive)?
Subacute combined degeneration of the spinal cord, also known as combined systems disease, is a nerve problem resulting from a lack of vitamin B12. This vitamin deficiency can happen due to lack of proper nutrition, problems absorbing nutrients because of changes in the stomach or its functions, or use of specific medications. The underlying issue is the removal of the protective coating of nerves, leading to damage in certain parts of the spinal cord. People with this condition often experience sensory problems, tingling sensation, weakness, unsteady movements, and trouble walking. In severe cases, if left untreated, it can even lead to stiffness and inability to move the legs. It is crucial to quickly identify and treat a vitamin B12 deficiency to prevent this serious nerve problem.
What Causes Subacute Combined Degeneration of the Spinal Cord (Archive)?
Subacute combined degeneration is a condition that happens when you don’t have enough vitamin B12. The body cannot produce this vitamin, so if you don’t get enough through the food you eat, you can end up with a deficiency.
Here are some primary causes of vitamin B12 deficiency:
Nutritional Deficiency:
Vitamin B12, also known as cobalamin, comes from our diet, usually from animal-based foods like meat, fish, dairy, eggs, and fortified cereals. Some of the best sources of vitamin B12 include clams and animal liver. Plants don’t contain cobalamin, so people on strict vegetarian and vegan diets sometimes don’t get enough. This is especially risky during times of increased need for vitamin B12, like during pregnancy or breastfeeding. Babies being breastfed by mothers who are deficient in vitamin B12 also risk becoming deficient unless they get an additional supplement.
Gastric Abnormalities:
Stomach issues can also contribute to vitamin B12 deficiency. Vitamin B12 in our food is bound to proteins. When we eat, our stomachs make acid that helps to free the vitamin B12 from these proteins. If someone has had gastric surgery or suffers from gastritis, they may not make enough of this acid. In turn, this can reduce the amount of vitamin B12 their body absorbs.
Another condition known as autoimmune gastritis, previously known
as pernicious anemia, is the most common cause of vitamin B12 deficiency. It involves the destruction of certain cells in the stomach, which leads to reduced vitamin B12 uptake.
Small Bowel Disease:
Diseases that affect the small intestine, such as inflammatory bowel disease, celiac disease and others, can also lead to vitamin B12 deficiency. This is because they interfere with the absorption of the vitamin from our food.
Pancreatic Disease:
A lack of appropriate pancreatic enzymes, which are needed to release vitamin B12 from proteins, can also contribute to deficiency, particularly in patients with conditions like pancreatic insufficiency or chronic pancreatitis.
Drug-Induced:
Certain medications, including some taken for diabetes and those that suppress stomach acid, can lead to a Vitamin B12 deficiency, too. Another substance that can lead to deficiency is nitrous oxide, which is sometimes used recreationally or as an agent for anesthesia.
Fish Tapeworm Infestation:
A tapeworm found in raw freshwater fish can lead to vitamin B12 deficiency when it competes with the host for vitamin B12 absorption.
Genetic Abnormalities:
Some newborns may also have genetic abnormalities that lead to vitamin B12 deficiency. These include conditions known as transcobalamin deficiency and Imerslund-Grasbeck syndrome.
Risk Factors and Frequency for Subacute Combined Degeneration of the Spinal Cord (Archive)
Vitamin B12 deficiency is a health condition that is more commonly found in older adults, with rates increasing as people age. Studies have shown that around 5% of the elderly have low vitamin B12 levels. In the United States and the United Kingdom, 6% of people 60 or older have a B12 deficiency, while 20% have borderline B12 levels. The main cause of this deficiency in older populations is malabsorption.
In developed countries, this deficiency is not common in children. However, it can affect babies who are breastfed by mothers who are vegans or themselves deficient in vitamin B12. In certain parts of the world like Latin America, the Indian subcontinent, and some parts of Africa, the prevalence of vitamin B12 deficiency is significantly higher. About 40% of children and adults in Latin America have low or marginal levels of vitamin B12, with a similar trend observed in India, Kenya, and among Bhutanese refugees.
The reason for the high rates of vitamin B12 deficiency in people from developing countries is mainly due to their diets, which lack foods rich in animal products. Pernicious anemia, another common cause of vitamin B12 deficiency, is most prevalent among Northern Europeans, particularly those of Scandinavian descent. However, not many studies have been done to understand the number of patients with this deficiency that show clinical or radiographic signs of a condition known as subacute combined degeneration. One study showed that about 14.8% of patients with low B12 levels who had clinical signs were found to have this condition upon imaging.
Signs and Symptoms of Subacute Combined Degeneration of the Spinal Cord (Archive)
When a doctor examines a patient, they try to figure out what might be causing the patient’s health issue. For example, in the case of B12 deficiency, the doctor might question the patient’s diet to spot any nutrional deficiencies. They might also ask about any gastrointestinal problems, like diarrhea or blood in the stool. If the patient is regularly passing fatty, greasy stools (a.k.a. steatorrhea), it might mean that they’re having trouble absorbing vitamin B12, possibly due to conditions like celiac disease or not having enough pancreatic enzymes.
The doctor also needs to know if the patient has a history of certain intestinal disorders or GI surgeries, as these could affect how well the body absorbs B12. Likewise, if the patient drinks a lot of alcohol, this could be important, since alcohol can change the size of red blood cells and also lead to poor diet. The doctor might also ask about the patient’s medication use, as well as their sexual history, since diseases like HIV or neurosyphilis can sometimes cause similar symptoms to B12 deficiency. Lastly, the doctor might ask about the patient’s family history, focusing on any genetic disorders or autoimmune diseases.
- Investigate patient’s diet
- Ask about gastrointestinal problems
- Identify malabsorption indicators like fatty stools
- Check history of intestinal disorders or GI surgeries
- Document alcohol intake
- Investigate patient’s medication use
- Ask about patient’s sexual history
- Look into patient’s family history
In some cases, the first symptoms of B12 deficiency are neurological and might appear before the blood tests show any abnormalities. Oftentimes, the symptoms affect both sides of the body equally and are associated with changes in the rear columns of the spinal cord, the spinal-cerebral tracts, and the lateral spinal cord tracts. Symptoms might also involve the nerves outside the spinal cord, vision problems, depression, and dementia.
Rear column spinal cord changes might affect the patient’s sense of touch, body position, and vibration. Initial symptoms might include tingling, burning, and loss of feeling, especially in the hands and feet. These symptoms might start in the upper or lower limbs, or in both at the same time. The patient might also experience a certain type of shock feeling when bending the neck forwards (Lhermitte’s sign). Difficulty keeping balance when they can’t use visual cues might also be an early sign of losing proprioception, or the sense of body position.
Changes in the lateral spinal cord tracts might cause muscle weakness, exaggerated reflexes, and muscle stiffness. Initially, stiffness might be the most noticeable symptom. Reflexes might be generally heightened, except in the ankles. Other signs of upper motor nerve damage, like foot clonus or babinski’s sign, might also be present. If untreated, these problems might progress to paralysis of all four limbs, or the entire body, and incontinence. Damage to the spinal-cerebral tracts might cause issues with gait, including sensory ataxia, which might manifest as a positive Romberg’s sign.
- Check for neurological symptoms
- Identify changes in sense of touch, body position, and vibration
- Look for muscle weakness, exaggerated reflexes, and muscle stiffness
- Monitor for gait issues
Anemia caused by underlying B12 deficiency might present as pallor, tiredness and in severe cases, signs of congestive heart failure. Glossitis, or inflammation of the tongue causing a beefy red appearance, may be seen due to the loss of tongue papillae. Also, a yellow-lemon tint in the skin from jaundice may also be observed.
Testing for Subacute Combined Degeneration of the Spinal Cord (Archive)
If you’re being checked for subacute combined degeneration, your doctor is likely to do several things:
First up, they’ll want to spot any blood abnormalities. They do this by taking a complete blood count and blood smear. One condition they’ll be looking out for is cobalamin deficiency, which might lead to a few specific issues, like macrocytosis (big red blood cells), anemia (low red blood cell count), and hypersegmented neutrophils (white blood cells with too many segments).
To confirm if you have low levels of vitamin B12, a substance called cobalamin, your doctor will need to test your B12 levels in your blood. This test can tell if your B12 levels are normal, borderline, or deficient. However, the levels don’t always give a clear picture of a deficiency, as they don’t measure the B12 available to your body’s tissues. This is why your doctor might also check the levels of substances involved in B12 metabolism, called methylmalonic acid (MMA) and homocysteine. An increase in these can confirm a B12 deficiency.
However, a rise in both MMA and homocysteine can suggest B12 deficiency, while a rise in homocysteine with normal MMA levels might point towards a folate deficiency, another type of vitamin deficiency. It’s also important to mention that other conditions, like renal failure, can lead to increased MMA levels.
Your doctor may also check your folate levels as folate deficiency can also cause similar symptoms to B12 deficiency. This could be especially relevant if you consume alcohol, have a diet low in folate, or have abnormal digestive health.
Classes of proteins called antibodies can also be detected to pinpoint the cause of B12 deficiency. If there’s no clear cause, your doctor might test for antibodies, such as anti-intrinsic factor antibodies and anti-parietal antibodies. These are often linked to a condition called pernicious anemia, which is a cause of B12 deficiency.
Finally, to spot any damage to the protective covering of nerve fibers, your doctor might take a look at your spine using an MRI scan. Changes in the spine, often seen as areas of brightness in the imaging, can indicate the early stages of the disease. These abnormalities can often be improved with prompt treatment.
Treatment Options for Subacute Combined Degeneration of the Spinal Cord (Archive)
Subacute combined degeneration, a disorder affecting nerves in your body, is usually treated using vitamin B12 supplements. These can be administered by injection, orally, or under your tongue. The two most commonly used types of vitamin B12 are cyanocobalamin and hydroxocobalamin. The type chosen, how it’s given, and for how long will depend on your symptoms, how urgent treatment is, what’s causing the condition in the first place, and what you are most comfortable with.
Generally, if your body isn’t able to absorb vitamin B12 properly, you may need a larger dose. People with subacute combined degeneration often need more aggressive and speedy treatment to prevent permanent damage to their nervous system. Initially, these patients are typically given the supplement by injection, and may switch to oral treatment once the deficiency has been addressed.
Injections are also suggested for those who may struggle to stick to oral treatment or those who have digestive issues that hinder absorption of the vitamin. If the cause of vitamin B12 deficiency is permanent, like a genetic condition or certain surgeries, lifelong supplementation is needed. Conversely, if the deficiency is due to causes that can be changed, such as diet or certain medications, treatment continues until the deficiency has been corrected.
The effectiveness of this treatment is determined by monitoring blood markers and symptom improvement. Usually, markers related to blood cell destruction decrease in 1 to 2 days, and an increase in immature red blood cells can be seen within 3 to 4 days. Anemia and unusually-shaped white blood cells improve within around 2 weeks, while a low white blood cell count and low platelet count typically take 3 to 4 weeks to resolve. Vitamin B12 levels are also regularly checked. However, improvements in neurological symptoms usually take longer, between 3 to 12 months.
It’s important to note that some neurological deficits may be permanent and won’t improve with treatment. While on this therapy, patients should also be monitored for a condition called hypokalemia, or low potassium levels in the blood, which can occur as red blood cells uptake potassium. If a patient doesn’t seem to respond to treatment, this could mean the patient isn’t taking the medication regularly, there may be a problem with absorption that was missed, or there might be a different cause that needs to be identified. In cases where blood markers don’t improve, the doctor may need to rule out other causes of anemia, such as iron deficiency.
What else can Subacute Combined Degeneration of the Spinal Cord (Archive) be?
There are several conditions that can appear quite similar to a condition known as subacute combined degeneration. These mimic its symptoms and can even show similar results in clinical scans. Some of these conditions include:
- Metabolic Deficiency or Toxicity: Deficiency of certain nutrients like copper and vitamin E can result in symptoms similar to this condition. Copper deficiency, for example, is often seen in people who have had gastrointestinal surgery, or suffer from zinc overload, malabsorption or malnutrition. Other conditions that can appear very similar include Vitamin E deficiency and methotrexate-induced myelopathy.
- Demyelinating Myelopathy: Conditions like transverse myelitis and multiple sclerosis can also mimic subacute combined degeneration. While these conditions also cause damage to the spinal cord, they have different patterns of damage and may affect fewer segments of the spinal cord. Multiple sclerosis usually affects younger patients and may come with additional symptoms like speech impairments, tremors, and irregular eye movements.
- Infectious Myelopathy: Certain infections can also create symptom patterns very similar to this condition. An example is vacuolar myelopathy which is seen in HIV-positive patients with low immune cell counts. Another similar condition is Tabes dorsalis, a form of late neurosyphilis that damages the back of the spinal cord and can come with sensory and bladder issues. Key differentiating features include involvement of the dorsal root, severe pain, and unique eye symptoms (Argyll Robertson pupils).
- Friedreich Ataxia: This genetic disorder that typically appears during adolescence can cause impaired proprioception (sense of self-movement), vibration, and depressed tendon reflexes. Some other symptoms include a form of heart disease, foot deformities, irregular eye movements, and high-arched feet.
- Leukoencephalopathy With Brainstem and Spinal Cord Involvement and Lactate Elevation: This genetic condition seen mostly in adolescents and children also involves the back and sides of the spinal cord. Unlike subacute combined degeneration, it affects the entire spinal cord and can extend into the brainstem. Conditions like sarcoidosis, ischemic lesions, and malignancies may also indicate similar symptoms.
What to expect with Subacute Combined Degeneration of the Spinal Cord (Archive)
In most people, their treatment stops the disease from getting worse, and it often leads to improvements in their neurological symptoms. These improvements can be seen both in their daily life and in their medical scans. However, the amount of improvement differs from person to person. It’s shown that while 86% of people see their symptoms lessen after treatment, only about 14% experience total recovery.
The severity of anemia, which is a condition marked by lack of healthy red blood cells, and the level of vitamin B12 in a person’s blood doesn’t influence the outlook of the nerve disorder known as subacute combined degeneration.
However, some people have traits that are linked to better short-term outcomes for their neurological health. Usually, these traits include:
- Being under the age of 50
- Having the disease for a short amount of time
- Not having any deficits in their senses
- Not showing the Romberg sign, which refers to loss of balance when eyes are closed
- Not showing the Babinski signs, where the big toe bends upwards when the sole of the foot is stimulated
- Having 7 or less affected segments of the spine shown on an MRI scan
- Having swelling in the spinal cord
- Showing contrast enhancement of the spine, which means that a dye used during an MRI scan highlights certain areas
- Not having any shrinkage of the spinal cord
Possible Complications When Diagnosed with Subacute Combined Degeneration of the Spinal Cord (Archive)
Subacute combined degeneration is a serious condition that, if not treated quickly, can lead to neurological issues like paraplegia or quadriplegia, which are forms of paralysis. It can also cause loss of control over bowel or bladder function. If the underlying problem of anemia isn’t addressed, it could lead to congestive heart failure, a condition where the heart isn’t able to pump sufficient blood to meet the body’s needs.
People with a condition called autoimmune gastritis are not just at risk for gastric carcinoma, a type of stomach cancer, and carcinoid tumors, but also other autoimmune conditions. These include type 1 diabetes, Hashimoto thyroiditis (a condition affecting the thyroid), vitiligo (a condition that causes loss of skin color), myasthenia gravis (a condition that causes muscle weakness), and rheumatoid arthritis (a condition causing joint inflammation and pain).
In pregnant women, a lack of vitamin B12, or a cobalamin deficiency, could increase the risk of spontaneous miscarriages, low birth weight babies, babies whose growth is restricted, and babies with neural tube defects, which are birth defects of the brain and spine. If a mother is deficient in Vitamin B12, her child is also at a higher risk of having problems with their nervous system as they develop and grow.
Common Concerns:
- Paraplegia or quadriplegia
- Bowel or bladder incontinence
- Congestive heart failure
- Gastric carcinoma and carcinoid tumors
- Other autoimmune conditions (type 1 diabetes, Hashimoto thyroiditis, vitiligo, myasthenia gravis, and rheumatoid arthritis)
- Increased risk of issues in pregnancy such as spontaneous miscarriages, low birth weight, growth restriction, and neural tube defects
- Neurodevelopmental abnormalities in children born to B12 deficient mothers
Preventing Subacute Combined Degeneration of the Spinal Cord (Archive)
The recommended daily amount of the vitamin B12 for healthy adults is 2.5 micrograms (mcg), but for pregnant women it is slightly higher at 2.6 mcg. Those following a strict vegetarian or vegan diet are advised to take vitamin B12 supplements to prevent a shortage of this important vitamin. It is especially critical for pregnant and breastfeeding women to get enough B12 to keep their babies healthy.
As we get older, around age 50 and beyond, our bodies might not absorb vitamin B12 as well. So, for older adults, it’s a good idea to include foods that are fortified with vitamin B12 in their diets. People who have had weight-loss surgery (bariatric surgery) need to take a vitamin B12 supplement indefinitely to keep their levels stable.
Screening, or checking for vitamin B12 levels might be needed for certain people. This includes people who often take medications called proton pump inhibitors and H2 antagonists, often used to reduce stomach acid, or metformin, a medicine for diabetes. For those who have had surgery to remove parts of the stomach or pancreas, screening may be useful too. If you’re going to have an operation where they use a gas called nitrous oxide for anesthesia, you might be screened for your vitamin B12 levels. This is because nitrous oxide can potentially affect how your body uses B12.
