A 34-year-old man experienced strange, involuntary movements in his hands and feet along with chest pain and weakness. Doctors discovered he had severe vitamin B12 deficiency, which damaged his spinal cord and caused a dangerous blood clot in his lungs. This is the first documented case showing this specific combination of symptoms. The good news: when doctors gave him vitamin B12 injections, his symptoms improved significantly. This case teaches us that vitamin B12 deficiency can cause serious complications beyond what we typically expect, and doctors should check B12 levels in patients with unexplained blood clots.

The Quick Take

  • What they studied: A single patient with unusual symptoms caused by severe vitamin B12 deficiency, including involuntary movements in all four limbs and a life-threatening blood clot in the lungs
  • Who participated: One 34-year-old male patient who presented with chest pain, weakness, numbness, and unusual trembling movements in his hands and feet
  • Key finding: Severe vitamin B12 deficiency caused spinal cord damage that led to involuntary writhing movements in all four limbs—a combination never documented before. The patient also developed a dangerous blood clot in his lung, likely due to high homocysteine levels from the B12 deficiency
  • What it means for you: If you experience unexplained weakness, numbness, unusual movements, or blood clots, ask your doctor to check your vitamin B12 levels. This case shows that B12 deficiency can cause serious complications that might be missed if doctors don’t think to test for it. Early treatment with B12 injections can prevent permanent nerve damage

The Research Details

This is a case report—a detailed medical story about one patient’s experience. The doctors carefully documented the patient’s symptoms, medical tests, imaging scans, and treatment response over time. They performed blood tests that showed extremely low B12 levels (below 159 pg/mL, which is severe), spinal cord imaging that revealed damage consistent with B12 deficiency, and chest imaging that discovered a large blood clot in the lungs. The patient received vitamin B12 injections as treatment, and doctors tracked how his symptoms changed afterward.

Case reports are valuable because they describe unusual or rare presentations of diseases that doctors might not otherwise recognize. While a single patient’s story cannot prove something works for everyone, it can alert the medical community to look for similar patterns in other patients. This case is particularly important because it documents a symptom combination that had never been reported before.

Understanding rare presentations of common diseases helps doctors recognize and treat them earlier. Vitamin B12 deficiency is treatable, but if doctors don’t suspect it, patients can suffer permanent nerve damage. Additionally, this case highlights a dangerous connection between B12 deficiency and blood clots that doctors should watch for. The unusual movement pattern described here—pseudoathetosis—is a specific sign that the brain has lost its ability to sense where the limbs are positioned, which is a hallmark of spinal cord damage from B12 deficiency.

This is a single case report, which is the lowest level of scientific evidence. It describes one patient’s experience in detail but cannot prove that all people with B12 deficiency will have the same symptoms or outcomes. However, the case is well-documented with laboratory tests, imaging studies, and clinical observations. The doctors clearly described what they found and how the patient responded to treatment. Readers should understand that while this case is interesting and teaches us something new, it represents one person’s experience, not a general rule for everyone with B12 deficiency

What the Results Show

The patient presented with a combination of symptoms that had never been documented together before: involuntary, slow, writhing movements in all four limbs (both hands and feet) caused by the brain’s inability to sense limb position. This occurred alongside chest pain, generalized weakness, and numbness in the hands and feet. Blood tests revealed severe vitamin B12 deficiency (less than 159 pg/mL), elevated homocysteine levels, and low counts of multiple blood cell types. Spinal cord imaging showed damage consistent with B12 deficiency affecting the nerve fibers responsible for sensing position and vibration.

Most critically, a chest scan revealed a large blood clot in the lungs—a life-threatening condition. This blood clot was likely caused by the elevated homocysteine levels resulting from the B12 deficiency. The patient was diagnosed with pernicious anemia, an autoimmune condition that prevents the body from absorbing B12 from food.

When treated with intravenous vitamin B12 injections, the patient experienced significant improvement in his neurological symptoms. The involuntary movements decreased, strength improved, and sensation began to return. This dramatic response to B12 treatment confirmed that the vitamin deficiency was the underlying cause of all his symptoms.

The patient’s blood work showed pancytopenia—low counts of red blood cells, white blood cells, and platelets—which is another consequence of severe B12 deficiency. The spinal cord imaging showed hyperintense signals (bright areas on MRI) in specific locations consistent with the pattern of damage seen in B12 deficiency. The patient’s neurological examination revealed impaired sensation to light touch and vibration in the lower extremities, which are classic signs of spinal cord damage from B12 deficiency. The absence of neck stiffness and normal cranial nerve function helped rule out other serious conditions like meningitis or brain inflammation.

Vitamin B12 deficiency is a well-known cause of spinal cord damage, and doctors regularly see symptoms like weakness, numbness, and tingling. However, the specific combination of involuntary movements (pseudoathetosis) affecting all four limbs in a symmetrical pattern had never been documented in the medical literature before. The connection between B12 deficiency and blood clots through elevated homocysteine is scientifically established, but this case demonstrates how serious that risk can be—resulting in a life-threatening pulmonary embolism. This case adds to our understanding by showing that B12 deficiency can cause more varied and severe complications than typically expected.

This is a single case report describing one patient, so we cannot generalize these findings to all people with B12 deficiency. Not everyone with B12 deficiency will develop these specific symptoms or a blood clot. The case does not include a control group or comparison to other patients, so we cannot determine how common this symptom combination is. We don’t know the patient’s long-term outcome beyond the initial improvement with treatment. The case also doesn’t explain why this particular patient developed such severe complications—genetic factors, other health conditions, or lifestyle factors may have played a role. Additionally, the report focuses on one patient’s experience, so it cannot establish cause-and-effect relationships or provide statistical data about risk

The Bottom Line

If you experience unexplained weakness, numbness, tingling, unusual movements, or blood clots, ask your doctor to check your vitamin B12 level. This is especially important if you have risk factors for B12 deficiency, such as pernicious anemia, certain digestive disorders, vegetarian or vegan diet, or use of certain medications. If B12 deficiency is diagnosed, vitamin B12 injections are an effective treatment that can prevent permanent nerve damage. People with B12 deficiency should also be monitored for blood clots, especially if they have elevated homocysteine levels. (Confidence level: Moderate—based on one well-documented case and established medical knowledge about B12 deficiency)

This case is particularly relevant for people experiencing unexplained neurological symptoms, those with known B12 deficiency, people with pernicious anemia, individuals with digestive disorders affecting nutrient absorption, vegetarians and vegans, older adults, and people who have experienced unexplained blood clots. Doctors should also pay attention to this case when evaluating patients with unusual movement disorders or blood clots of unknown cause. People without B12 deficiency symptoms do not need to change their behavior based on this single case, but maintaining adequate B12 intake through diet or supplementation is always good practice

If B12 deficiency is treated with injections, some symptoms may improve within days to weeks, as seen in this patient. However, nerve damage that has been present for a long time may take months to fully recover, and some permanent damage may not be reversible. The involuntary movements in this case improved significantly with treatment, suggesting that early intervention is important. Blood clot symptoms would require immediate emergency treatment and would not improve on their own

Want to Apply This Research?

  • Track B12 levels and homocysteine levels every 3-6 months if you have been diagnosed with B12 deficiency or pernicious anemia. Also log any neurological symptoms such as numbness, tingling, weakness, unusual movements, or balance problems to share with your doctor
  • If you have B12 deficiency, set reminders for your B12 injections or oral supplements as prescribed by your doctor. Track your dietary B12 intake if you take oral supplements. If you experience new symptoms like chest pain, shortness of breath, or unusual movements, log these immediately and contact your healthcare provider
  • Maintain a symptom diary noting any changes in strength, sensation, coordination, or movement quality. Track B12 injection dates and any side effects. Monitor for warning signs of blood clots such as chest pain, shortness of breath, leg swelling, or calf pain, and seek immediate medical attention if these occur. Schedule regular follow-up appointments with your doctor to reassess B12 levels and symptom progression

This article describes a single case report and should not be used for self-diagnosis or self-treatment. If you experience symptoms like weakness, numbness, unusual movements, or chest pain, consult a healthcare professional immediately. Vitamin B12 deficiency requires proper medical diagnosis through blood tests and should be treated under medical supervision. Blood clots are life-threatening emergencies requiring immediate hospital care. This information is educational and does not replace professional medical advice, diagnosis, or treatment. Always consult with your doctor before starting any new supplements or treatments