Does methylcobalamin (Vitamin B12) have a role in managing central vertigo?

Methylcobalamin Does Not Have an Established Role in Central Vertigo Management

Methylcobalamin (vitamin B12) is not indicated for central vertigo, as the evidence linking B12 deficiency to vertigo pertains exclusively to peripheral vestibular dysfunction and neurological complications, not central vestibular pathology. The distinction between peripheral and central vertigo is critical here, as the mechanisms and treatment approaches differ fundamentally.

Understanding the Evidence Context

The available evidence addresses B12 deficiency in three relevant contexts, none of which support its use in central vertigo:

Peripheral Vestibular Disorders Only

• Mecobalamin combined with vestibular rehabilitation training shows efficacy specifically for acute vestibular neuritis, a peripheral vestibular disorder, with meta-analysis demonstrating reduced dizziness handicap inventory scores at 6 months (Z=3.20, P=0.001) 1
• Studies investigating homocysteine, vitamin B12, and folic acid levels in vertigo patients examined only peripheral vestibular dysfunction (Meniere's disease, vestibular neuronitis, and BPPV), finding no significant relationship between B12 levels and these peripheral conditions 2
• One case report described reversible splenial lesions (RESLES) with isolated vertigo in a patient with B12 deficiency, but this represents a rare metabolic/structural brain lesion rather than typical central vertigo 3

Neurological Manifestations of B12 Deficiency

B12 deficiency causes distinct neurological syndromes that differ from central vertigo:

• The primary neurological manifestations include subacute combined degeneration of the spinal cord (funicular myelosis), sensorimotor polyneuropathy, optic neuropathy, and cognitive disorders - not isolated central vertigo 4
• Neuromuscular symptoms include gait ataxia, paraesthesia, muscle weakness, abnormal reflexes, and spasticity, primarily from loss of sensory function (proprioceptive, vibratory, tactile) rather than vestibular pathology 5
• Demyelination occurs extensively in the spinal cord and peripherally in dorsal root ganglion neurons, with focal demyelination in brain white matter - these are not vestibular nuclei or central vestibular pathway lesions 5

When B12 Testing Is Actually Indicated

Guidelines specify clear indications for B12 assessment that do not include central vertigo:

• B12 deficiency should be excluded in patients presenting with anemia, isolated macrocytosis, established polyneuropathies, neurodegenerative diseases, or psychosis - not vertigo 5
• For polyneuropathy evaluation, serum B12 was abnormally low in only 3.6% of patients, with metabolic deficiency (elevated methylmalonic acid and homocysteine) found in an additional 5-10% 5
• Functional B12 deficiency (normal serum levels but elevated MMA) affects various populations but manifests as neuromuscular dysfunction, not isolated central vertigo 6

Clinical Algorithm for Vertigo and B12

If evaluating a patient with central vertigo:

1. Focus on central causes: stroke, demyelinating disease (MS), posterior fossa tumors, migraine-associated vertigo, medication effects 5
2. Do not routinely measure B12 unless other neurological signs suggest deficiency (polyneuropathy, cognitive impairment, macrocytic anemia, spinal cord signs) 5
3. If B12 deficiency is incidentally discovered, treat it for its own complications (preventing stroke via homocysteine reduction, treating neuropathy), but do not expect resolution of central vertigo 5

If B12 deficiency is present with neurological symptoms:

• Use methylcobalamin or hydroxycobalamin rather than cyanocobalamin, as recommended for stroke prevention and neurological complications 5, 7
• Initial therapy: 1000 micrograms intramuscularly three times weekly for 2 weeks, then 1000 micrograms monthly 6
• Both methylcobalamin and adenosylcobalamin are essential; hydroxocobalamin or cyanocobalamin provides both pathways 7

Critical Distinction

The Meniere's disease guideline extensively discusses management of peripheral vertigo but makes no mention of B12 supplementation as a treatment consideration, despite comprehensive coverage of dietary modifications, medications, and complementary therapies 5. This absence is telling - if B12 had a role in vestibular disorders, it would appear in these authoritative guidelines.

Central vertigo requires investigation for serious CNS pathology, not empiric B12 supplementation. The one case report linking B12 deficiency to vertigo involved a rare metabolic encephalopathy (RESLES), not typical central vestibular dysfunction 3.