Brief overview
- Diagnosis: Physical examination (reflexes), magnetic resonance imaging, blood and nerve tests, Schilling test (measurement of vitamin B12 uptake).
- Symptoms: At the beginning, often insensitivity in both legs, disturbed sense of position, vibration and touch, unsteadiness of gait; later also spastic paralysis of legs and arms; abnormal reflexes, mental disorders, “pernicious anemia”
- Causes: Damage to the protective myelin sheaths of the spinal cord nerves as a result of a deficiency mostly of vitamin B12, more rarely folic acid or copper deficiency
- Risk factors:Vitamin B12-deficient diet (in the case of a strict vegan or vegetarian diet), damage to the stomach lining due to alcohol abuse or chronic inflammation, removal of parts of the stomach or intestines, increased vitamin requirement due to pregnancy; infections with certain fungi or the fish tapeworm; cancer
- Prognosis: If therapy is started early, symptoms can be completely reversed; if treatment is delayed, irreversible consequences up to paraplegia are possible.
- Prevention:If the diet is low in vitamin B12 or vitamin B12-free, it is advisable to take appropriate dietary supplements. The same applies to diseases that inhibit the absorption or utilization of the vitamin or in the case of increased vitamin requirements, for example during pregnancy.
What is funicular myelosis?
Funicular myelosis (funicular spinal disease) is a rare disease that mainly affects people between the ages of 50 and 70. It is characterized by (reversible) damage to the posterior region of the spinal cord (hind cord). The spinal cord runs protected in the spinal canal from the coccyx to the head and is part of the central nervous system.
In most cases, funicular myelosis is caused by a vitamin B12 deficiency (hypovitaminosis). Vitamin B12 (also called cobalamin) has many functions in the body. Among other things, it is important for nerve cells and red blood cells.
Humans absorb vitamin B12 primarily through dairy products, meat, eggs and whole grain products. The vitamin is stored in the body in relatively large quantities and over a long period of time. The main storage is in the liver. Funicular myelosis usually occurs when these stores are completely depleted.
How is funicular myelosis diagnosed?
The symptoms of funicular myelosis prompt most affected individuals to visit their primary care physician or neurologist.
Taking the medical history (anamnesis)
First of all, the physician asks the patient for his or her medical history (anamnesis). For example, he asks about the onset, type and extent of the symptoms.
During the physical examination, the doctor will test the sensation of position, touch, vibration, pain and temperature. In addition, he tests the reflexes. The focus of the examination is usually on the legs if funicular myelosis is suspected, as the symptoms are usually most obvious there.
Blood test
Of particular importance in the diagnosis of funicular myelosis is blood testing. Signs of anemia caused by vitamin deficiency are often noticeable. In this context, the following parameters are important, among others:
- Blood cells: Number and appearance are analyzed
- Vitamin B12
- Folic acid
- Holo-transcobalamin: This is an early marker of vitamin B12 deficiency. A decreased level indicates that more vitamin B12 is being consumed than absorbed.
- Methylmalonic acid: An elevated level of methylmalonic acid indicates vitamin B12 deficiency.
- Parietal cell antibodies (PCA): The parietal cells of the gastric mucosa produce intrinsic factor. Antibodies against these cells hinder the production of the protein.
- Indirect bilirubin
- Cholesterol
Magnetic resonance imaging (MRI).
To analyze the damage to the spinal cord in more detail, an image is obtained using magnetic resonance imaging (MRI) if funicular myelosis is suspected. Characteristic of funicular myelosis are abnormalities in the posterior (posterior cord) and lateral posterior (posterior cord) regions of the spinal cord.
Neurophysiological examinations
Schilling test (vitamin B12 absorption test)
If funicular myelosis is suspected, the Schilling test (vitamin B12 absorption test) is sometimes used. For this, the patient takes radioactively labeled vitamin B12. Over the next 24 hours, the doctor analyzes the patient’s urine to see how much of the radiolabeled vitamin has been excreted. If it is less than five percent, this indicates an absorption disorder.
To prevent radiolabeled cobalamin from being stored in the body, the patient is injected with unlabeled vitamin B12 into a muscle during the test. It saturates the body tissue with cobalamin.
However, the use of the Schilling test for suspected funicular myelosis is controversial. Some experts consider it unnecessary.
Sternal puncture (sternal puncture)
For further investigation of anemia, the physician sometimes performs a so-called sternal puncture. To do this, he uses a fine needle to remove some bone marrow from the patient’s sternum to have it analyzed in the laboratory.
Clarification of gastritis (inflammation of the gastric mucosa)
In the case of pernicious anemia (literally: a “perishable” anemia), as occurs with a vitamin B12 deficiency, chronic gastritis (inflammation of the gastric mucosa) often develops. This results in digestive problems and, again, vitamin deficiencies because not enough hydrochloric acid is released into the stomach for digestion (called “histamine refractory anacidity”). Gastritis is a case for a gastroenterologist.
Exclusion of other diseases
Funicular Myelosis: Symptoms
In most cases, funicular myelosis develops gradually, only rarely rapidly and acutely. Initially, a vitamin B12 deficiency becomes noticeable through anemia (pernicious anemia, literally: “perishable anemia”). In this form of anemia, the red blood cells are enlarged (megaloblastic) and have an increased concentration of the blood pigment hemoglobin (hyperchromic).
Funicular myelosis is a variant clinical picture. It primarily affects the spinal cord, but also the brain (encephalopathy). Damage to the brain is manifested by cognitive (perception) impairment. Mental symptoms range from fatigue to dementia and psychotic symptoms.
Sensory disturbances in the legs
Rarely, early stage funicular myelosis results in motor deficits such as paralysis.
Spastic paralysis
Funicular myelosis progresses and leads to further damage to the spinal cord and brain over time. As a result, gait disturbances increase significantly as the disease progresses. Eventually, spastic paralysis of the legs and later the arms occur.
Disturbances of the reflexes
Muscle reflexes are increased by funicular myelosis in many cases or – if a polyneuropathy is present at the same time – decreased. Polyneuropathy is a disease characterized by damage to a large number of nerves and often occurs in funicular myelosis.
Disorders of bladder, bowel and sexual function
In about a quarter of cases, funicular myelosis leads to bladder symptoms. These include an initially increased urge to urinate, which in many cases later develops into incontinence. The function of the rectum is often also disturbed. In some cases, there is a risk of impotence.
Other consequences of vitamin B12 deficiency
Funicular myelosis and anemia are not the only consequences of vitamin B12 deficiency. In addition, damage occurs to the mucous membranes that require vitamin B12. Particularly noticeable is an inflammatory and painful tissue atrophy of the tongue (Hunter’s glossitis).
In addition, homocysteinemia sometimes occurs: The amino acid homocysteine is not metabolized due to vitamin B12 deficiency, which increases its concentration in the blood. This condition leads to vascular damage, some of which is dangerous.
Causes and risk factors
Vitamin deficiency causes damage to the myelin sheath of certain nerve cells through a mechanism that is not yet known.
Damage in the spinal cord
Initially, funicular myelosis particularly affects the rear region (posterior cord) of the spinal cord. As the disease progresses, it often spreads, for example, to the so-called posterior cord.
The spinal cord consists mainly of the so-called gray matter, the nerve cell bodies, and the white matter, in which the nerve processes are located. The nerve processes are enclosed in a fatty sheath called the myelin sheath to improve electrical signal transmission. In funicular myelosis, these myelin sheaths swell initially triggered by vitamin deficiency. The swelling is reversible with early treatment.
Gradual onset
Vitamin B12 deficiency and thus funicular myelosis usually develop slowly because the body stores the vitamin in relatively large amounts (up to four milligrams). Since the daily requirement is only a few micrograms, the store provides sufficient vitamin B12 for years. If a cobalamin deficiency occurs, various causes are possible.
Vitamin B12 deficiency due to insufficient intake
Only in rare cases is nutrition to blame for vitamin B12 deficiency. For example, it is possible that a strict vegetarian or vegan diet leads to reduced levels of vitamin B12 in the blood. Vitamin B12 is produced in nature only by microorganisms and is found primarily in animal products such as meat, eggs and dairy products.
Vitamin B12 deficiency due to inadequate absorption
In most cases, vitamin B12 deficiency and thus funicular myelosis are caused by insufficient vitamin B12 absorption in the gastrointestinal tract. This so-called absorption disorder occurs in 80 percent of cases due to the deficiency of a transport protein that is required for the absorption of the vitamin. This protein is called intrinsic factor. It binds to vitamin B12 and brings it to special docking sites (receptors) in the small intestine, where the vitamin is absorbed into the blood.
Intrinsic factor is produced and released by certain cells in the stomach lining. In some gastric diseases (such as chronic atrophic gastritis) or after the removal of a part of the stomach, it is possible that sufficient intrinsic factor is no longer produced. In this case, there is a long-term risk of funicular myelosis.
Some intestinal diseases or partial removal of the small intestine also lead to impaired absorption of vitamin B12. Possible causes include chronic intestinal inflammation (such as ulcerative colitis), tuberculosis infections, gluten intolerance, amyloidosis and connective tissue diseases.
Vitamin B12 deficiency due to increased consumption
Only in rare cases is increased vitamin B12 consumption responsible for funicular myelosis. For example, during pregnancy and lactation, the need and thus the consumption of cobalamin increases. Some infectious diseases caused by fungi, bacteria or fish tapeworms also lead to an increased vitamin requirement. The same applies to diseases with a high rate of new cell formation (such as cancer).
Vitamin B12 deficiency due to impaired utilization
Folic acid deficiency
In a few cases, funicular myelosis develops as a result of a deficiency of folic acid. This then develops (like the deficiency of cobalamin) either as a result of inadequate intake, impaired absorption, impaired utilization, or when consumption is increased.
An insufficient supply of folic acid is caused, for example, by chronic alcohol consumption or anorexia. Intestinal absorption is impaired by chronic intestinal diseases (such as Crohn’s disease, celiac disease), liver cell damage or certain medications (such as oral contraceptives or the painkiller acetylsalicylic acid), among others.
The utilization of folic acid may also be disturbed by certain medications (for example, cancer drugs) or in the case of congenital disorders in folic acid metabolism. As with vitamin B12, there is an increased consumption of folic acid during pregnancy and lactation, as well as in diseases with a high rate of cell formation (such as cancer).
Treatment of funicular myelosis
Therapy for vitamin B12 deficiency
Funicular myelosis is usually characterized by the fact that all body stores of vitamin B12 have been emptied. Treatment therefore begins with what is known as saturation, i.e.: initially, those affected not only cover the acute daily requirement of cobalamin (two to five micrograms), but the physician also replenishes the stores through the appropriate dosage. For this purpose, the physician usually injects one milligram of vitamin B12 into the muscle daily during the first two weeks of therapy.
Subsequently, a permanent therapy treats the vitamin deficiency (and thus the funicular myelosis) with cobalamin injections once or twice a week or even only once a month. Vitamin B12 tablets are available as an alternative to the injections.
Therapy for folic acid deficiency
In the further course, a balanced diet is usually sufficient to maintain a sufficient folic acid level in the body. In the case of increased folic acid requirements (as in the case of pregnancy), affected individuals take folic acid as a dietary supplement.
Acute treatment with folic acid and vitamin B12
The combined administration of folic acid and vitamin B12 is only advisable in acute cases, as long as the cause of the funicular myelosis is not yet known. Folic acid administration improves the symptoms affecting the blood, but does not prevent the neurological symptoms caused by funicular myelosis in the case of vitamin B12 deficiency. As a result, folic acid administration may mask vitamin B12 deficiency. Funicular myelosis caused by cobalamin deficiency would then not be detected and treated early.
Course of the disease and prognosis
The early start of treatment is crucial for the course of the disease, since the symptoms of funicular myelosis will only disappear if no permanent damage to the nerve cell processes (axons) has yet occurred.
Immediately after starting treatment, it is possible that symptoms will initially worsen before improving.
Almost always, therapy causes at least some relief of symptoms within days to weeks. However, if no improvement is noticeable after three months, the physician will reexamine the diagnosis of funicular myelosis.
Symptoms that have already existed for months or even years often do not completely regress. In some patients with funicular myelosis, residual symptoms remain despite therapy.
Prevention
Dietary supplements containing vitamin B12, folic acid or both are one option, especially for people who abstain from eating animal foods. However, those affected should only take these after consulting their doctor. According to the German Nutrition Society, a diet that covers the need for vitamin B12 is currently not possible with exclusively plant-based and vegan foods.
