“Pregnancy in adult-onset idiopathic inflammatory myopathy”: Report from a cohort of myositis patients from a single center

Background and purpose

Idiopathic inflammatory myopathies (IIM) are systemic diseases, characterized by the presence of an inflammatory muscle infiltrate. Although more frequent in women, its relationship with pregnancy has not been extensively studied. Our goal was to analyze the interaction between pregnancy and myositis in a cohort of IIM women from a single center.

Methods

A total of 51 patients from a historical cohort of IIM diagnosed between 1983 and 2013 were interviewed with a specific questionnaire. Comparisons between pregnancies occurring before and after the onset of the disease were performed using generalized mixed-effect models with normal and binomial distributions adjusted for confounding factors and clustering.

Results

A total of 102 pregnancies from 51 patients (41 with dermatomyositis and 10 with polymyositis) were analyzed. A total of 14 pregnancies from 8 patients occurred after disease onset; statistically significant (p = 0.02) clinical improvement during gestation was evident in 7 pregnancies (4 patients), 5 of them (from 2 patients) experienced a relapse of IIM symptoms afterwards, while in the rest, there was no influence of pregnancy on the disease. No disease flare associated with pregnancy was observed. Two patients were diagnosed within the first 6 months after delivery and none during pregnancy. No evidence was found to support pregnancy as a trigger for myopathy (p = 0.71).

Conclusions

Pregnancy does not seem to carry a worse prognosis for the mother nor for the fetus in patients with IIM; on the contrary, nearly half of the patients in our series improved clinically when they became pregnant, a relapse of IIM symptoms being common afterwards. Pregnancy does not appear to be a trigger for IIM.     

A case of Sjögren’s syndrome presenting as hypokalemic myopathy due to distal renal tubular acidosis

We report a case of hypokalemic myopathy with distal renal tubular acidosis which leads to the diagnosis of Sjögren’s syndrome (SS). A 67-year-old man was admitted to our department for progressive muscle weakness and myalgia. Laboratory data demonstrated hypokalemia with hyperchloremic acidosis, elevated muscle enzyme and inability to acidify urine. Findings of interstitial nephritis, which is consistent with renal tubular acidosis in SS, were found on renal biopsy. Remarkable changes of the renal tubule, including tubular atrophy, dilatation and intratubular casts, were observed. Potassium replacement therapy normalized the marked elevated urinaryβ ₂-microglobulin excretion as well as the improvement of muscle symptoms. Taken together with our findings, it it suggested that sustained hypokalemia may partly contribute to the exacerbation of the pre-existing renal tubular disorder in SS.     

Mitochondrial genetic analysis in a Chinese family suffering from both mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes and diabetes

To investigate the mitochondrial mutations in patients suffering from both mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) and maternally inherited diabetes. MELAS was confirmed by muscle biopsy performed from the biceps muscle of the proband. Mitochondrial DNA (mtDNA) was isolated from peripheral blood mononuclear cells. The significant mtDNA loci of other 14 family members were further detected according to the sequencing results of the proband. Direct sequencing of PCR products was used to identify the mitochondrial mutations. The proband (III 1) and her brother (III 3) both harbored the tRNALeu (UUR) A3243G mutation, with heteroplasmic levels of 50% and 33% respectively. Moreover, another two mitochondrial variants, A8860G and A15326G, were also detected in the samples of all the family members. MELAS and diabetes can coexist in one patient, and the main cause for these diseases is the tRNALeu (UUR) A3243G mutation. However, other gene variants may contribute to its pathogenesis. This case also supports the concept that both syndromes can be regarded as two phenotypes of the same disease.     

Demographic and clinical features of inclusion body myositis in north America

Introduction: Few studies of the demographics, natural history, and clinical management of inclusion body myositis (IBM) have been performed in a large patient population. To more accurately define these characteristics, we developed and distributed a questionnaire to patients with IBM. Methods: A cross‐sectional, self‐reporting survey was conducted. Results: The mean age of the 916 participants was 70.4 years, the male‐to‐female ratio was 2:1, and the majority reported difficulty with ambulation and activities of daily living. The earliest symptoms included impaired use and weakness of arms and legs. The mean time from first symptoms to diagnosis was 4.7 years. Half reported that IBM was their initial diagnosis. A composite functional index negatively associated with age and disease duration, and positively associated with participation in exercise. Conclusions: These data are valuable for informing patients how IBM manifestations are expected to impair daily living and indicate that self‐reporting could be used to establish outcome measures in clinical trials. Muscle Nerve 52: 527–533, 2015