Can vitamin B12 and folate deficiency cause tremors?

Vitamin B12 and Folate Deficiency Can Cause Tremor

Yes, vitamin B12 and folate deficiency can cause tremor and other movement disorders, including extrapyramidal symptoms such as parkinsonism, chorea, and dystonia. These neurological manifestations can occur with or without the classic hematological findings of deficiency 1, 2.

Neurological Manifestations of B12 Deficiency

Vitamin B12 deficiency can present with a wide range of neurological symptoms beyond the well-known subacute combined degeneration of the spinal cord:

• Tremor
• Parkinsonism features (mask-like facies, cogwheel rigidity)
• Chorea
• Myoclonus
• Dystonia
• Gait abnormalities

These movement disorders may:

• Appear before other classic signs of deficiency
• Be the presenting symptom without anemia
• Sometimes worsen transiently after initiating B12 replacement therapy 2

Case Evidence

A particularly illustrative case reported a 55-year-old man who presented with a 10-day history of:

• Slowness of activities
• Mild tremors of hands
• Low volume speech
• Mask-like facies
• Reduced blink rate
• Cogwheel rigidity

Laboratory testing revealed vitamin B12 deficiency, and the patient showed dramatic improvement following intramuscular B12 injections. At five-year follow-up, he remained functionally independent with no neurological deficits 1.

Pediatric Presentations

Children can also present with movement disorders due to B12 deficiency. A study of 38 pediatric patients with neurological symptoms of B12 deficiency found:

• Hand tremor
• Hypotonia
• Inability to sit/walk without support
• Gait ataxia

All patients recovered within one month after vitamin B12 supplementation 3.

Mechanism of Action

The exact pathophysiology of movement disorders in B12/folate deficiency is not fully understood, but likely involves:

1. Impaired methylation reactions in the central nervous system
2. Accumulation of homocysteine (neurotoxic)
3. Disruption of neurotransmitter metabolism
4. Possible damage to basal ganglia structures

Important Clinical Considerations

1. Urgent treatment is essential: Vitamin B12 deficiency with neurological involvement should be treated immediately to prevent permanent damage 4.

2. Folate caution: Folic acid supplementation may mask severe vitamin B12 depletion and can potentially worsen neurological symptoms by allowing progression of subacute combined degeneration of the spinal cord 4, 5.

3. Treatment protocol: For B12 deficiency with neurological involvement (including tremor):

   • Hydroxocobalamin 1 mg intramuscularly on alternate days until no further improvement
   • Then hydroxocobalamin 1 mg intramuscularly every 2 months for maintenance 4
   • Urgent specialist advice from neurologist and hematologist should be sought 4

4. Always check both B12 and folate: Before initiating folate treatment, always check and treat vitamin B12 deficiency first to avoid precipitating neurological complications 4, 5.

Key Pitfalls to Avoid

• Don't miss the diagnosis: Movement disorders may be the only presenting symptom of B12 deficiency, even without anemia or macrocytosis 3.

• Don't give folate alone: Administering folic acid without checking B12 status can mask B12 deficiency while allowing neurological damage to progress 4, 5.

• Don't delay treatment: Neurological symptoms require immediate treatment to prevent permanent damage 4.

• Don't stop at normal hemoglobin: Normal hemoglobin and MCV don't rule out B12 deficiency as a cause of neurological symptoms 3.

Vitamin B12 and folate deficiencies are treatable causes of movement disorders that should be considered in the differential diagnosis of any patient presenting with tremor or other extrapyramidal symptoms.