[Rhabdomyolysis and myopathy as the only manifestations of severe hypothyroidism secondary to Hashimoto's thyroiditis]

Prevalence of temporomandibular disorders in patients with Hashimoto thyroiditis

OBJECTIVES

Autoimmune thyroid disease (AITD), also known as Hashimoto thyroiditis (HT), is a degenerative inflammatory disease with high prevalence among women and has been associated with fibromyalgia and widespread chronic pain. The goal was to determine the frequency of temporomandibular disorders (TMD) in patients with HT.

METHODS

In all, 119 women (age 19-60 years) were divided into a study (52 women diagnosed with HT) and a control (67 healthy individuals, of which 15 were excluded) group. Serum concentrations of thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), anti-thyroglobulin (Tg) and anti-thyroid peroxidase (TPO) antibody levels were measured. The temporomandibular jaw and muscles were examined using the German Society of Functional Diagnostics and Therapy guidelines. The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) was used to assess TMD. Standardized questionnaires, incorporating epidemiological criteria, state and treatment of the thyroid disease, Helkimo Index (HI), and Fonseca Anamnestic Index (FAI), were filled out by all patients.

RESULTS

The two groups did not differ in terms of demographic parameters or mandibular jaw mobility. Significantly higher levels of anti-TPO and anti-Tg were attested in all subjects of the HT group. Markedly elevated prevalence of TMD was found in the HT group. Muscle pain and stiffness were found in 45 (86.5%) subjects of the HT group (p < 0.001), of whom 33 (63.4%) also had disc displacement with reposition (p < 0.001). Whereas 50% of the control group showed no TMD symptoms, all subjects in the HT group had symptoms.

CONCLUSIONS

A significantly elevated prevalence of TMD was found in patients with HT. Thus, patients with TMD who do not respond to therapy should be referred for thyroid diagnostic workup.

Hypothyroid myopathy: A peculiar clinical presentation of thyroid failure. Review of the literature

Abnormalities in thyroid function are common endocrine disorders that affect 5-10 % of the general population, with hypothyroidism occurring more frequently than hyperthyroidism. Clinical symptoms and signs are often nonspecific, particularly in hypothyroidism. Muscular symptoms (stiffness, myalgias, cramps, easy fatigability) are mentioned by the majority of patients with frank hypothyroidism. Often underestimated is the fact that muscle symptoms may represent the predominant or the only clinical manifestation of hypothyroidism, raising the issue of a differential diagnosis with other causes of myopathy, which sometimes can be difficult. Elevated serum creatine kinase, which not necessarily correlates with the severity of the myopathic symptoms, is certainly suggestive of muscle impairment, though it does not explain the cause. Rare muscular manifestations, associated with hypothyroidism, are rhabdomyolysis, acute compartment syndrome, Hoffman's syndrome and Kocher-Debré-Sémélaigne syndrome. Though the pathogenesis of hypothyroid myopathy is not entirely known, proposed mechanisms include altered glycogenolytic and oxidative metabolism, altered expression of contractile proteins, and neuro-mediated damage. Correlation studies of haplotype, muscle gene expression and protein characterization, could help understanding the pathophysiological mechanisms of this myopathic presentation of hypothyroidism.