IVIG Versus PLEX in the Treatment of Worsening Myasthenia Gravis: What is the Evidence?: A Critically Appraised Topic.

BACKGROUND: Immune therapies such as intravenous immunoglobulin (IVIG) and plasma exchange (PLEX) are first line in the treatment of worsening myasthenia gravis. Although PLEX is favored in myasthenic crisis, IVIG is increasingly used in exacerbations due to cost and ease of administration. OBJECTIVES: To review and critically assess current evidence on the effects of IVIG and PLEX on functional outcomes in patients with worsening myasthenia gravis. METHODS: A structured critical appraisal was conducted on the objective topic. This included a creation of a structured question based on a clinical scenario, comprehensive literature search, selection of evidence for review, and critical appraisal of selected evidence. Evidence was summarized and commentary provided. Participants included consultant and resident neurologists, a medical librarian, clinical epidemiologists, and content experts in the field of neuromuscular neurology. RESULTS: A single-blinded, randomized-controlled trial that compared IVIG and PLEX in 84 patients with worsening myasthenia gravis was selected for review. Primary outcome measure was functional status at 14 days after treatment, as assessed by the Quantitative Myasthenia Gravis Score. Change in Quantitative Myasthenia Gravis Score at day 14 for all subjects was 4.0, without statistically significant differences between IVIG and PLEX groups. CONCLUSIONS: IVIG and PLEX are equally effective in worsening myasthenia gravis. Treatment decisions may depend on several variables, including presence of respiratory distress, medical comorbidities, access to medication, and cost. PLEX will likely remain the treatment of choice in true myasthenic crisis.

Recurrent myoglobinuria in a sporadic patient with a novel mitochondrial DNA tRNA(Ile) mutation.

The differential diagnosis of myoglobinuria includes multiple etiologies, such as infection, inflammation, trauma, endocrinopathies, drugs toxicity, and primary metabolic disorders. Metabolic myopathies can be due to inherited disorders of glycogen metabolism or to defects of fatty acid oxidation. Primary respiratory chain dysfunction is a rare cause of myoglobinuria, but it has been described in sporadic cases with mutations in genes encoding cytochrome b or cytochrome c oxidase (COX) subunits and in four cases with tRNA mutations. We describe a 39-year-old woman with myalgia and exercise-related recurrent myoglobinuria, who harbored a novel mitochondrial DNA mutation at nucleotide 4281 (m.4281A>G) in the tRNA-isoleucine gene. Her muscle biopsy revealed ragged-red and COX-deficient fibers. No deletions or duplication were detected by Southern blot analysis. The m.4281A>G mutation was present in the patient's muscle with a mutation load of 46% and was detected in trace amounts in urine and cheek mucosa. Single-fiber analysis revealed significantly higher levels of the mutation in COX-deficient (65%) than in normal fibers (45%). This novel mutation has to be added to the molecular causes of recurrent myoglobinuria.

Copper deficiency myeloneuropathy due to occult celiac disease.

INTRODUCTION: Copper deficiency is an increasingly recognized cause of gait unsteadiness. Recognized causes of copper deficiency include excess zinc ingestion, and malabsorption. Although hematologic abnormalities have been attributed to copper deficiency in patients with celiac disease, myeloneuropathy due to copper deficiency has not been well described in patients with celiac disease. CASE REPORT: A 69-year-old woman was evaluated for a 5-year history of progressive gait unsteadiness and weight loss. She had no other gastrointestinal symptoms. Her neurologic examination revealed a sensory ataxia, and electrodiagnostic testing confirmed a myeloneuropathy. She had decreased serum copper levels and markedly elevated gliadin and tissue transglutaminase antibodies. Subsequent duodenal biopsy showed findings consistent with celiac disease. The patient was diagnosed with copper deficiency myeloneuropathy due to celiac disease. Adoption of a gluten-free diet along with copper supplementation resulted in significant clinical improvement, including improvement on electrodiagnostic testing. CONCLUSIONS: Celiac disease should be considered in patients found to have copper deficiency, even in patients without gastrointestinal symptoms. Furthermore, the authors suggest that some cases of ataxia associated with celiac disease are likely due to copper deficiency myeloneuropathy.