What is subacute combined degeneration of the spinal cord?

It is a neurological complication of Vitamin B12 deficiency involving demyelination of the posterior columns and corticospinal tracts.

Why does Vitamin B12 deficiency cause neurological symptoms?

Vitamin B12 is essential for myelin synthesis. Deficiency leads to nerve damage and impaired nerve conduction.

What is the significance of a positive Romberg sign?

A positive Romberg sign indicates impaired proprioception, commonly due to posterior column involvement.

What is glossitis in Vitamin B12 deficiency?

Glossitis is inflammation of the tongue, often presenting as a smooth, red, and painful tongue.

Can Vitamin B12 deficiency cause anemia?

Yes. It typically causes megaloblastic macrocytic anemia due to impaired DNA synthesis.

What blood film finding is characteristic of Vitamin B12 deficiency?

Hypersegmented neutrophils and macro-ovalocytes are characteristic findings.

Why is LDH elevated in Vitamin B12 deficiency?

LDH rises because of ineffective erythropoiesis and increased destruction of abnormal red blood cell precursors.

Can severe Vitamin B12 deficiency lead to heart failure?

Yes. Severe anemia can cause high-output cardiac failure with edema and breathlessness.

What is pernicious anemia?

Pernicious anemia is an autoimmune disorder causing intrinsic factor deficiency and impaired Vitamin B12 absorption.

Is folic acid alone sufficient treatment?

No. Folic acid may improve anemia but can worsen or mask neurological complications of Vitamin B12 deficiency.

What is the preferred treatment for Vitamin B12 deficiency with neurological involvement?

Hydroxocobalamin 1000 mcg intramuscularly on alternate days until no further improvement, then every 3 months lifelong if indicated.

Can neurological deficits be reversed?

Neurological recovery is often possible if treatment is started early, but prolonged deficiency may cause permanent damage.

Which sensory modality is commonly affected first?

Vibration sense and proprioception are commonly affected early due to posterior column involvement.

Is lifelong Vitamin B12 therapy necessary?

Lifelong therapy is usually required in irreversible causes such as pernicious anemia or after total gastrectomy.

Vitamin B12 Deficiency with Subacute Combined Degeneration Quiz

🩺 Internal Medicine Quiz: Vitamin B12 Deficiency with Subacute Combined Degeneration

Q: What causes Vitamin B12 deficiency?

Common causes include pernicious anemia, dietary deficiency, gastrectomy, malabsorption syndromes, and certain medications.

📖 History

A 52-year-old woman presented with progressive weakness of both lower limbs for 3 days and is now unable to walk without assistance. She also complained of bilateral leg swelling for 10 days. Associated symptoms include tingling and numbness of lower limbs, palpitations, sore mouth and exertional breathlessness for one month.

🩺 Examination

General and neurological examination findings need to be interpreted to identify the underlying diagnosis.

🔬 Investigations

Laboratory and neurological investigations are required to establish the diagnosis and identify complications.

❓ MCQ Questions

Q1. Most likely diagnosis?

A. Multiple sclerosis
B. Guillain-Barré syndrome
C. Vitamin B12 deficiency with subacute combined degeneration and anaemic heart failure
D. SLE with myelitis

Q2. Expected general examination findings?

A. Anaemia & pallor
B. Glossy tongue
C. Bilateral pitting oedema
D. Vitiligo
E. Jaundice
F. Pyrexia

Q3. Expected neurological findings?

A. Loss of ankle reflexes
B. Loss of vibration sense
C. Positive Romberg sign
D. UMN signs
E. Cognitive decline
F. Optic atrophy

Q4. Investigations?

A. CBC, ESR, LDH, Reticulocyte count
B. Bone marrow study
C. Nerve conduction study
D. Vitamin B12 and Folate assay
E. Echocardiography
F. Serum ferritin

Q5. Specific treatment?

A. Folic acid
B. Hydroxocobalamin regimen
C. Oral Cyanocobalamin
D. IV Iron sucrose

📋 Brief Case Summary

Middle-aged woman with progressive neuropathy, gait difficulty, lower limb weakness, glossitis, oedema, palpitations and exertional dyspnoea suggesting severe Vitamin B12 deficiency complicated by subacute combined degeneration of the spinal cord and anaemic heart failure.

✅ Click to Reveal Answers

Q1: C

Q2: A, B, C, D, E

Q3: A, B, C, D (E and F may occur in advanced disease)

Q4: A, B, C, D, E

Q5: B

📚 Answer Explanation

Vitamin B12 deficiency causes megaloblastic anaemia and neurological dysfunction. Involvement of posterior columns and corticospinal tracts produces subacute combined degeneration. Severe anaemia may lead to high-output cardiac failure causing oedema and breathlessness.

❌ Why Not Others?

Multiple sclerosis usually presents with CNS demyelination without megaloblastic anaemia.
Guillain-Barré syndrome causes acute ascending paralysis but not glossitis or macrocytic anaemia.
SLE myelitis usually has systemic autoimmune manifestations.
Iron deficiency anaemia does not explain posterior column signs.

📝 Five Brief Case Scenarios

Vegetarian woman with numb feet and macrocytosis.
Elderly male with gait ataxia and positive Romberg sign.
Pernicious anaemia patient with glossitis and neuropathy.
Post-gastrectomy patient with sensory loss.
Metformin user developing progressive paraesthesia.

🧠 Pathophysiology Simplified

Vitamin B12 deficiency impairs DNA synthesis causing megaloblastic anaemia. It also disrupts myelin formation leading to degeneration of posterior columns and corticospinal tracts.

🔍 Physical Examination Pearls

Pallor is usually marked.
Glossitis is a classic clue.
Loss of vibration sensation occurs early.
Positive Romberg sign suggests posterior column disease.
Combined LMN and UMN signs may coexist.

🔬 Investigation Findings

Macrocytic anaemia
High MCV
Hypersegmented neutrophils
Elevated LDH
Low serum B12 level
Megaloblastic bone marrow

⚠️ Complications

Permanent neuropathy
Gait instability
Heart failure
Cognitive impairment
Optic neuropathy

💊 Management

Hydroxocobalamin replacement
Treat anaemia
Manage heart failure if present
Physiotherapy
Identify underlying cause

📑 Differential Diagnosis

Guillain-Barré syndrome
Multiple sclerosis
Copper deficiency
Cervical myelopathy
SLE myelitis

🚨 Clinical Pitfalls

Giving folate alone may worsen neurological damage.
Neurological signs may precede anaemia.
Normal haemoglobin does not exclude B12 deficiency.

💎 Clinical Pearls

Glossitis + neuropathy = think B12 deficiency.
Loss of vibration sense is highly suggestive.
Early treatment prevents irreversible deficits.

📅 Monitoring & Follow-Up

Repeat CBC
Monitor neurological recovery
Assess B12 replacement compliance
Lifelong follow-up in pernicious anaemia

📈 Prognosis

Excellent if treated early. Delayed treatment may result in permanent neurological disability.

❓ FAQ (15)

1. What causes Vitamin B12 deficiency?
Dietary deficiency, pernicious anaemia, gastrectomy and malabsorption.

2. What is subacute combined degeneration?
Demyelination of posterior columns and corticospinal tracts.

3. Why is Romberg positive?
Loss of proprioception.

4. What is glossitis?
Smooth painful tongue.

5. Is anaemia always present?
No.

6. Can neuropathy be reversed?
Often if treated early.

7. What blood film finding is classic?
Hypersegmented neutrophils.

8. Why is LDH elevated?
Ineffective erythropoiesis.

9. Can heart failure occur?
Yes, in severe anaemia.

10. What is pernicious anaemia?
Autoimmune intrinsic factor deficiency.

11. Is folate enough?
No.

12. What is first-line treatment?
Hydroxocobalamin.

13. Is lifelong therapy required?
Often yes.

14. Can cognitive decline occur?
Yes.

15. Which sensory modality is affected first?
Vibration sense.

📚 References

Davidson's Principles and Practice of Medicine
Harrison's Principles of Internal Medicine
Oxford Handbook of Clinical Medicine
British Society for Haematology Guidelines

🔑 SEO Keywords

Vitamin B12 deficiency, Subacute Combined Degeneration, Megaloblastic Anaemia, Neurology MCQ, Internal Medicine Quiz, Pernicious Anaemia, Macrocytic Anaemia, Posterior Column Disease, Positive Romberg Sign, Glossitis, Hydroxocobalamin Treatment, Anaemic Heart Failure, Vitamin B12 MCQ, FCPS Medicine Quiz, Clinical Case Challenge

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