Is there a link between Benign Paroxysmal Positional Vertigo (BPPV) and thyroid problems, such as those caused by Graves' disease or Hashimoto's thyroiditis, or their treatments?

Association Between BPPV and Thyroid Disease

There is an established link between BPPV and thyroid autoimmunity, particularly Hashimoto's thyroiditis, though the relationship with Graves' disease is less well-documented. The evidence suggests that patients with autoimmune thyroid disease have higher rates of BPPV, and conversely, BPPV patients show increased prevalence of thyroid autoantibodies 1, 2.

Evidence for the Association

Hashimoto's Thyroiditis and BPPV

Patients with BPPV demonstrate significantly higher serum TSH levels and anti-thyroid autoantibody levels compared to healthy controls 1. The most compelling evidence comes from prospective studies showing:

• Almost one-fifth (approximately 20%) of euthyroid patients with Hashimoto's thyroiditis had signs of BPPV 1
• Patients with BPPV had significantly elevated thyroid autoantibodies (TPO-Ab and TG-Ab) compared to controls 1
• More than half of patients with Ménière disease (a related vestibular disorder) had positive anti-thyroid or non-organ-specific autoantibodies, compared to less than 30% of healthy controls 1

Impact on BPPV Recurrence

Hypothyroidism on hormone replacement therapy is associated with increased risk of BPPV recurrence, particularly in patients with Hashimoto's thyroiditis 2. Specifically:

• 24.4% of patients with recurrent BPPV had hypothyroidism on long-term hormone replacement therapy, compared to only 14.4% of patients without recurrence (p = 0.0006) 2
• Hashimoto's thyroiditis was strongly associated with BPPV recurrence (p < 0.0001) 2
• Recurrence correlated significantly with elevated serum TPO-Ab (p = 0.0117) and TG-Ab (p = 0.0025) levels, but not with TSH, free T3, or free T4 levels 2

This suggests the autoimmune process itself, rather than thyroid hormone levels, drives the association 2.

Treatment Response Considerations

Hypothyroidism is identified as a factor associated with failed first canalith repositioning maneuver (CRP) 3. The presence of thyroid disease may modify treatment outcomes and should be considered when managing BPPV patients 3.

Conflicting Evidence

One study from 2015 found no statistical relationship between BPPV and thyroid autoimmunity, with similar rates of elevated thyroid antibodies across BPPV patients (16%), non-BPPV vertigo patients (11.5%), and controls (25%) 4. However, this contradicts the more recent and larger prospective studies 1, 2.

Clinical Implications

For Patients with Thyroid Disease

Patients with Hashimoto's thyroiditis or other autoimmune thyroid disease should be carefully evaluated for vestibular symptoms 1. Even slight symptoms potentially related to vestibular dysfunction warrant thorough investigation 1.

The BPPV guidelines note that thyroid eye disease (associated with Graves' disease or Hashimoto's thyroiditis) can present with periorbital edema, conjunctival changes, and proptosis, though these represent orbital manifestations rather than direct vestibular effects 5.

For Patients with BPPV

Patients presenting with BPPV, particularly those with recurrent episodes, are candidates for thyroid autoimmunity screening 1. This should include:

• TSH measurement 1, 2
• Anti-TPO antibodies 1, 2
• Anti-thyroglobulin antibodies 1, 2

Treatment Considerations

The presence of hypothyroidism does not contraindicate standard BPPV treatment with canalith repositioning procedures, though these patients may require additional maneuvers or have higher recurrence rates 2, 3. The BPPV guidelines emphasize that comorbidities should be assessed as modifying factors in management 5.

Proposed Mechanism

The association appears driven by autoimmune mechanisms rather than thyroid hormone levels themselves, as recurrence correlates with antibody titers but not with TSH or thyroid hormone levels 2. The exact pathophysiology remains unclear, but may involve:

• Cross-reactivity of thyroid autoantibodies with inner ear antigens 1
• Shared autoimmune susceptibility affecting both thyroid and vestibular systems 1, 2
• Potential effects on calcium metabolism affecting otoconia formation 2

Important Caveats

The relationship between Graves' disease specifically and BPPV is not well-established in the literature 5. Most evidence focuses on Hashimoto's thyroiditis and general thyroid autoimmunity 1, 2. The thyroid eye disease associated with Graves' disease represents orbital pathology rather than vestibular dysfunction 5.

Levothyroxine treatment itself does not appear to cause or prevent BPPV, as the association relates to autoimmune markers rather than thyroid hormone levels 2. However, patients on long-term hormone replacement therapy with underlying Hashimoto's thyroiditis have increased recurrence risk 2.