Causes of a Positive Romberg Sign
A positive Romberg sign is primarily caused by vitamin B12 deficiency, but can also result from other proprioceptive pathway deficiencies affecting the dorsal columns of the spinal cord.
Pathophysiology of Romberg Sign
The Romberg test evaluates proprioception and balance by having a patient stand with feet together and eyes closed. A positive sign occurs when the patient can maintain balance with eyes open but sways or falls when eyes closed, indicating:
- Loss of proprioceptive input from the lower limbs
- Inability to compensate for this loss without visual input
- Dysfunction in the dorsal column-medial lemniscus pathway
Primary Causes of Positive Romberg Sign
1. Vitamin B12 Deficiency
- Most common and significant cause 1, 2, 3, 4
- Leads to demyelination of the dorsal columns of the spinal cord
- Causes subacute combined degeneration affecting proprioceptive pathways
- Can present with neurological symptoms even with normal hemoglobin levels 2
2. Other Nutritional Deficiencies
- Vitamin E deficiency
- Copper deficiency (rare)
- Folate deficiency (often coexisting with B12 deficiency) 1
3. Neurological Conditions
- Tabes dorsalis (neurosyphilis)
- Multiple sclerosis
- Cervical myelopathy 5
- Peripheral neuropathies affecting large sensory fibers
Clinical Presentation with Vitamin B12 Deficiency
Patients with a positive Romberg sign due to B12 deficiency often present with:
- Paresthesias and numbness in extremities
- Loss of vibration and position sense
- Ataxic gait
- Progressive weakness
- Hyperreflexia 4
- Cognitive changes (irritability to severe dementia) 2
Diagnostic Approach
When a positive Romberg sign is detected:
Laboratory testing:
- Serum B12 levels (total or active B12)
- Methylmalonic acid (MMA) and homocysteine levels (more sensitive markers)
- Complete blood count (may show macrocytic anemia)
- Folate levels 1
Interpretation thresholds for B12:
- <180 ng/L: Confirmed deficiency
- 180-350 ng/L: Indeterminate (requires additional testing)
350 ng/L: Unlikely deficiency 1
Enhanced Assessment: Walking Romberg Test
The walking Romberg test is more sensitive than the traditional standing test:
- Patient walks 5 meters with eyes open, then repeats with eyes closed
- Swaying, instability, or inability to complete the walk with eyes closed indicates a positive result
- Detects proprioceptive deficits in 74.5% of patients with cervical myelopathy (vs. 34% with traditional Romberg) 5
Treatment Implications
Early detection and treatment of B12 deficiency is crucial:
- Vitamin B12 deficiency left untreated for >3 months may cause permanent spinal cord damage 6
- Intramuscular B12 injections (1000-2000 μg) are the standard treatment 1, 4
- Neurological symptoms may not fully respond to treatment if diagnosis is delayed 2
Special Considerations
- Elderly patients are at higher risk due to age-related decline in B12 absorption 1
- Patients with atrophic gastritis have intrinsic factor deficiency leading to B12 malabsorption 3
- Vegetarians/vegans require B12 supplementation as it's not present in plant foods 7, 6
- Medications that suppress gastric acid production can contribute to B12 deficiency 1, 2
Early recognition of a positive Romberg sign and prompt investigation for vitamin B12 deficiency can prevent irreversible neurological damage and significantly improve patient outcomes.