Spinal Cord Subacute Combined Degeneration

What is Spinal Cord Subacute Combined Degeneration?

Subacute combined degeneration (SCD) is a disease that affects specific areas of the spinal cord due to the deterioration of a protection layer called myelin. This condition commonly happens in people who don’t have enough vitamin B12, resulting in blood and nervous system problems. Common signs of this disease include feeling less sensitive, feeling “pins and needles”, weakness, lack of coordination, and difficulties with walking.

Vitamin B12 aids in the creation of DNA, the genetic material found in all cells, and myelin, which protects our nerves. SCD can occur if you’re not eating enough foods that contain vitamin B12, or if your body isn’t able to absorb it. This might be because of some surgeries, certain medications, or an overgrowth of bacteria.

Also, using and overusing a gas called nitrous oxide can cause SCD. Consuming too much zinc can also lead to this disease by causing a lack of copper in the body. Although these causes are less frequent, they should still be considered. If a person has unexplained anemia (a lack of red blood cells) and neurological symptoms, doctors should check for vitamin B12 or, in rarer cases, copper deficiency.

What Causes Spinal Cord Subacute Combined Degeneration?

SCD, which affects the spinal cord, is usually caused by a lack of vitamin B12. You mainly get vitamin B12 from food, especially meat, eggs, and dairy. The body absorbs this vitamin in a part of your gut called the ileum, with the help of something your stomach makes called the intrinsic factor. If something disturbs your diet, your body’s ability to absorb the vitamin or the activity of the intrinsic factor, it can lead to a lack of vitamin B12. This deficiency can then cause the troubles seen in SCD.

Though dietary deficiency is a rare cause of vitamin B12 deficiency (because our liver stores of the vitamin can last up to three years), it can happen in certain cases. For instance, strict vegans or older individuals, especially those in care facilities, may not get enough vitamin B12 from their diets. If you have unexplained anemia along with other autoimmune conditions such as vitiligo or thyroiditis, your doctor may suspect a vitamin B12 deficiency. In such cases, pernicious anemia, an autoimmune condition where your body attacks the cells in your stomach making the intrinsic factor, may be the cause.

Sometimes, problems with absorbing vitamin B12 from food can lead to its deficiency as well. This can happen if you’ve had surgery on your stomach that makes the intrinsic factor, or other surgeries like gastric bypass. Some diseases that affect your small intestine, such as inflammatory bowel disease, sprue (a type of gluten intolerance), radiation enteritis (the inflammation of your small intestine from radiation therapy), lymphoma, and amyloidosis can also hinder your body’s ability to absorb the vitamin. Specifically, celiac disease can lead to vitamin B12 deficiency if you’re not sticking to a gluten-free diet. Moreover, an operation that removes a part of your ileum can lead to a deficiency by reducing the area where the vitamin gets absorbed. Finally, an overgrowth of bacteria in your small intestine related to motility disorders and structural problems (such as a blind loop or diverticulitis), or infections like fish tapeworm can also interfere with the absorption of vitamin B12.

Some medicines, like metformin, proton pump inhibitors, and nitrous oxide, can also cause a vitamin B12 deficiency. Proton pump inhibitors, which reduce stomach acid, can hinder the separation of vitamin B12 from the proteins in your diet. Metformin, a common drug for diabetes, can cause a vitamin B12 deficiency by interfering with the ileum’s calcium-dependent absorption of the vitamin. Interestingly, this effect can be reversed with calcium supplements.

Repeated use of nitrous oxide, popularly known as “laughing gas,” can also cause SCD. It does this by rendering the vitamin B12 in your body inactive, disrupting certain biochemical processes that maintain the protective sheath around your nerve fibers and lead to their degeneration.

In addition to vitamin B12 deficiency, a lack of copper has also been identified as a potential cause of SCD. Similar to the former, the causes and symptoms of copper deficiency can include gastric bypass and small bowel resection. Copper deficiency can cause similar neurological problems seen in SCD. It can also lead to anemia (a lack of red blood cells) or pancytopenia (a reduction in all types of blood cells). An excessive intake of zinc can also cause copper deficiency.

Risk Factors and Frequency for Spinal Cord Subacute Combined Degeneration

Some research has been done on a condition called subacute combined degeneration (SCD) of the spinal cord, but it isn’t common in all patients with a vitamin B12 deficiency. An MRI study showed that almost 15% of patients with this deficiency showed signs of SCD. However, treatment generally reverses these changes.

• Vitamin B12 deficiency is the most common cause of SCD, especially in older people, especially those living in assisted living facilities. This is usually due to not eating enough B12-rich foods over a long time.
• In developing countries, up to 40% of people have low or borderline low B12 levels.

SCD can also be caused by a lack of copper in the body, but it’s rare and the exact number of cases is unknown. The most common reasons for copper deficiency include surgery on the upper part of the digestive system, too much zinc in the body, and problems with absorbing food.

Lastly, the abuse of a drug called nitrous oxide, or ‘Whippits’, can also cause SCD. Its use has greatly increased over the past 10 years, making it the second most common recreational drug used by 16-24-year-olds in the UK. About 3.4% of people who use nitrous oxide have signs of SCD.

Signs and Symptoms of Spinal Cord Subacute Combined Degeneration

If someone is suspected of having Subacute Combined Degeneration (SCD) of the spinal cord, a detailed neurological examination might reveal several symptoms. These can include muscle stiffness or weakness in both legs (spastic paraparesis), an inability to maintain balance when the eyes are closed (impaired Romberg sign), and loss of various sensations such as the ability to perceive vibration, body position, and differentiation between two points. Other symptoms might include unsteady walking (ataxic gait) and a general decrease in sensing touch or temperature.

These symptoms occur because of the harmful effects on certain nerve pathways in the spinal cord. There might also be symptoms related to peripheral neuropathies (conditions that result when nerves carrying messages to and from the brain and spinal cord from and to the rest of the body are damaged or diseased), usually affecting the lower limbs. Additionally, the person may experience a gradual decline in mental function. In some cases, Vitamin B12 deficiency, which is reversible and can improve with quick treatment, can cause both the mental decline and the nerve symptoms.

Several risk factors should be considered when diagnosing this disease. These include a history of Crohn’s or celiac disease, medication use, history of autoimmune diseases, and dietary habits. The doctor might ask about the patient’s long-term use of certain medications like proton pump inhibitors and metformin. Any history of surgery, especially in the gastrointestinal region, should also be noted. Dietary details should include whether the patient is vegetarian or vegan, and whether they take supplements such as zinc and copper. It’s also important to ask about the use of nitrous oxide (Whippits), particularly in younger patients. Additionally, diseases such as type I diabetes, thyroid diseases, and vitiligo could suggest the presence of pernicious anemia — an underlying condition that can lead to SCD.

From a blood-related perspective, most patients will exhibit symptoms like fatigue, pale complexion (pallor), and a general feeling of discomfort or unease (malaise). These symptoms relate back to an underlying issue of megaloblastic anemia. During the physical examination, pallor and yellowness of the skin (jaundice) may be noted, which occur due to increased red blood cell turnover. Glossitis, or inflammation of the tongue, might also be present. This condition arises from impairment in DNA synthesis that affects rapidly dividing cells such as those in the tongue.

Testing for Spinal Cord Subacute Combined Degeneration

When a doctor suspects a medical condition due to symptoms related to the nervous system and anemia, they will conduct a series of tests. These tests include a full count of your blood cells, a blood smear examination, and assessments of the levels of vitamin B12 and folate in your body.

A particular index, the Mean Corpuscular Volume (MCV), can show if you have a form of anemia characterized by larger than normal red blood cells referred to as macrocytic anemia. Here, MCV values of over 100 fL indicate macrocytic anemia. Such anemia could also occur without any noticeable symptoms. However, an MCV over 115 fL may suggest a deficiency in B12 and also help distinguish it from other triggers of macrocytosis, which is an enlargement of red blood cells.

Upon examining your blood smear, certain characteristics like hypersegmented neutrophils and macro-ovalocytes could be seen. These are signs typically linked to a specific form of anemia known as megaloblastic anemia. While this type of anemia can result from deficiencies in folate or vitamin B12, neurological symptoms are rarely associated with folate deficiency.

In both B12 and folate deficiencies, a substance in your blood known as homocysteine can increase. But when there’s another substance known as methylmalonic acid (MMA) that’s also elevated, it points more towards a B12 deficiency. Therefore, if both MMA and homocysteine levels are high, it suggests a B12 shortage. Only a raise in homocysteine with normal MMA levels suggests a folate deficiency.

MMA serves as a more reliable marker of deficiencies than homocysteine or B12 levels. Therefore, if you’ve been using nitrous oxide and your B12 levels are normal but MMA is high, that could suggest a deficiency in B12. Furthermore, if you have symptoms of subacute combined degeneration (SCD), which include nerve damage and anemia, but your B12 and MMA levels are normal, your doctor may need to check for levels of copper, ceruloplasmin, and zinc to rule out a condition known as copper deficiency myelopathy.

Interestingly, you could have neurological symptoms even without anemia. In such a scenario, a doctor may order a full spine MRI. This imaging procedure could reveal bright or “hyperintense” areas localized to a part of your spinal cord known as the posterior columns. Although less common, these bright spots could show up on cervical and thoracic spinal cord images.

Lastly, it’s also necessary to investigate potential dietary deficiencies and digestive conditions, for instance, Crohn’s or celiac disease that could be causing your symptoms. Also, if you have a history of autoimmune disorders, it may be crucial to check for substances known as anti-intrinsic factor antibodies. These antibodies might interfere with the absorption of B12 in your body. In cases involving symptoms of myelopathy, which include weakness and/or sensory impairments in the lower extremities, an MRI of the cervical or upper thoracic spine can be highly valuable. This imaging often shows symmetric “hyperintensity” in the dorsal columns, a region at the back of the spinal cord often forming an “Inverted V” sign. Quick treatment can resolve these abnormal MRI findings swiftly.

Treatment Options for Spinal Cord Subacute Combined Degeneration

Subacute combined degeneration (SCD) of the spinal cord is treated by taking extra vitamin B12. This can be in the form of a pill (oral) or an injection (parenteral). The way you take your vitamin B12, and how long you’ll need to take it for, depends on the condition that caused your B12 levels to drop in the first place. For instance, people with Crohn’s disease or celiac disease will need to be monitored for signs of low vitamin B12. In cases of certain long-term conditions that can deplete B12 levels, like celiac disease, pernicious anemia, and Crohn’s disease after surgery, you may need to continuously take additional vitamin B12.

If your dietary intake of vitamin B12 is low, then oral supplements may be prescribed. If you are experiencing severe symptoms, like anemia or serious neurological disorders including SCD, you might need to have injections of vitamin B12. This is because when the condition is severe, a more rapid response is needed to prevent permanent neurological damage. Initially, injections may be used until the deficiency is under control; then, oral supplements may be sufficient to maintain normal vitamin B12 levels.

Injections are also used when malabsorption is the cause, such as in celiac disease or pernicious anemia. However, even for these conditions, if the dose is high enough, oral supplements can be effective at maintaining adequate vitamin B12 levels. Recent studies have shown that oral vitamin B12 is just as good as injections at increasing vitamin B12 levels in the blood. This means even if you have trouble absorbing nutrients, you might still be able to get enough vitamin B12 with high-dose oral supplements.

What else can Spinal Cord Subacute Combined Degeneration be?

If a person is experiencing symptoms of Spinal Cord Dysfunction (SCD), it’s important to consider some other conditions that could cause similar problems. A few examples include:

• Copper Deficiency: This can occur in some people after weight-loss surgery, people who’ve had too much exposure to a treatment called chelators for a condition called Wilson’s disease, or people who’ve taken in excessive amounts of zinc. This could be through supplements or even swallowing too much denture cream. A simple blood test can check for copper and zinc levels.
• Methotrexate-Induced Myelopathy and Vitamin E Deficiency: These are conditions that can look a lot like SCD. They are diagnosed based on a history of methotrexate use or with blood tests to measure vitamin E, B12, MMA, and homocysteine levels.
• Transverse Myelitis: This is an inflammatory condition that usually affects 1 or 2 sections of the spinal cord but it’s not just in the dorsal columns like SCD. A symptom includes a feeling like a tight band around the trunk of the body. The condition can be seen on a special type of MRI scan of the spine.
• Multiple Sclerosis: This condition presents with symptoms that are distributed over time and can involve various parts of the body. Symptoms not typical for SCD might include issues with the bowel and bladder or cerebellum problems.
• Tabes Dorsalis: This is a form of advanced syphilis. It impacts the dorsal columns of the spinal cord like SCD but is associated with sensory imbalance and sharp limb pain along with a history of syphilis. This condition can be ruled out with a careful medical history and examination. When necessary, lab tests for syphilis can be included in the investigation process.
• HIV Vacuolar Myelopathy: HIV-positive patients with low CD4 counts may present with similar symptoms to SCD. A history of HIV, low CD4 counts, opportunistic infections, illnesses defining acquired immunodeficiency syndrome, and malignancy can assist in diagnosis.
• Epidural tumors and cervical spondylosis myelopathy can be ruled out with a spine MRI.

It’s important to remember that these conditions present in ways similar to SCD, hence, careful evaluation is required for an accurate diagnosis.

What to expect with Spinal Cord Subacute Combined Degeneration

People with a medical condition called SCD who are spotted early on and given proper treatment tend to have positive results concerning their brain function. However, some people may still experience long-term, moderate to severe neurological problems, particularly if they stop their treatment. While the majority of patients show improvements after treatment, only a small percentage fully recover.

When treated with vitamin B12 supplements, most patients experience quick improvements in their blood health, with the destruction of red blood cells slowing down. The severity of anemia and the level of vitamin B12 in the blood don’t influence how well a patient with SCD will do in the long run. However, individuals with certain characteristics tend to have better short-term neurological outcomes.

These characteristics include:

• Being younger than 50 years old
• Having a short duration of the disease
• Not having sensory deficits, or a reduced ability to feel things
• Not showing a Romberg sign, which is a loss of balance
• Not showing Babinski signs, a foot response indicating potential brain or spinal cord injury
• Having 7 or less affected spinal segments visible on an MRI scan
• Having spinal cord fluid accumulation
• Having contrast enhancement of the spine on MRI which helps the doctor to see the details more clearly
• Not having spinal cord thinning

Possible Complications When Diagnosed with Spinal Cord Subacute Combined Degeneration

Subacute combined degeneration (SCD) of the spinal cord can result in permanent neurological problems in patients. This may include partial paralysis, weakness in the legs, and difficulty with sensing one’s environment, like struggling to maintain balance. Also, a vitamin B12 deficiency caused by pernicious anemia is linked to a higher rate of stomach cancer. This occurs due to atrophic gastritis, an inflammation that thins the stomach’s lining. For these reasons, it’s recommended to test for these conditions in at-risk groups. In uncommon situations, if you don’t treat a vitamin B12 deficiency, the consequences can be significant and serious, such as severe anemia and a dangerously overworked heart, leading to high-output cardiac failure.

Common Outcomes:

• Permanent neurological issues due to SCD
• Partial paralysis
• Weakening of leg strength
• Difficulties in sensing physical environment
• Raised likelihood of stomach cancer from vitamin B12 deficiency
• Severe inflammation thinning the stomach’s lining
• Rarely, severe anemia and a potentially dangerous overworked heart due to untreated B12 deficiency

Preventing Spinal Cord Subacute Combined Degeneration

Spinal cord damage due to vitamin deficiency (known as SCD) can be prevented and treated. However, routinely taking vitamin B12 as a preventative measure isn’t usually necessary, except in certain circumstances. People who adhere strictly to a vegan diet, for instance, may deplete their stocks of vitamin B12 in 2 to 3 years as they might not be getting enough from their diet. In such instances, they would need to regularly take supplemental B12.

This is especially important advice for women strictly following a vegan diet who are thinking about getting pregnant. This is because the growing baby would also need vitamin B12 from the mother’s body.

After certain types of weight-loss surgery, such as gastric or bariatric surgery, people may need vitamin B12 supplements due to the surgery’s impact on their body. Specifically, these surgeries can remove the “intrinsic factor” produced by the stomach, which is a substance necessary for absorbing B12. Similarly, those who have a portion of their small intestine removed may need B12 supplements because they’ve lost some of their body’s area for absorbing B12.

Additionally, before undergoing surgery where “nitrous oxide” (a common gas used for anesthesia) is used, it’s a good idea to test for B12 deficiency. This is because nitrous oxide can stop “methylcobalamin” (a form of B12 important for nerve function and making red blood cells) from working effectively. Regular monitoring of complete blood counts, which gives information about the body’s red and white blood cells, is important to ensure that any issues regarding vitamin B12 are promptly addressed.