A pilot study of neuromuscular ultrasound as a biomarker for amyotrophic lateral sclerosis.

INTRODUCTION: This study explores the reliability and responsiveness of neuromuscular ultrasound in amyotrophic lateral sclerosis (ALS). METHODS: Investigations were conducted with 10 healthy controls, 10 patients with ALS (single point in time), and 10 different patients with ALS (followed over 6 months; 4 completed follow-up). Ultrasound was used to measure the thickness of the geniohyoid, bilateral biceps/brachialis, bilateral tibialis anterior, and bilateral hemidiaphragms (at inspiration and expiration). Interrater and intrarater reliability and change in muscle thickness over 6 months were measured. RESULTS: Interrater correlation coefficients ranged between 0.80 and 0.99 in healthy controls and between 0.78 and 0.97 in patients with ALS. Intrarater correlation coefficients ranged between 0.83 and 0.98 in healthy controls. The mean percentage decline in muscle thickness over 6 months was 20.25%. DISCUSSION: Muscle ultrasound appears to be a reliable technique for measuring important muscles in patients with ALS. Larger studies with age-matched controls should be conducted to assess further the responsiveness of this biomarker in ALS. Muscle Nerve 59:181-186, 2019.

Assessing the accuracy of neuromuscular ultrasound for inclusion body myositis.

INTRODUCTION: Inclusion body myositis (IBM) can have clinical and electrodiagnostic features similar to other neuromuscular diseases, making it a diagnostic challenge. This prospective study was designed to determine the accuracy of forearm ultrasound for IBM. METHODS: Sixty adults were recruited (15 with IBM, 15 with amyotrophic lateral sclerosis [ALS], 15 with other myopathies, and 15 healthy controls), and each underwent ultrasound of the bilateral forearms (imaging the flexor digitorum profundus and flexor carpi ulnaris muscles). Three clinicians with varying ultrasound expertise assigned a diagnosis of IBM, ALS, other myopathy, or control, based on images alone. RESULTS: Intrarater reliability was moderately strong. Interrater reliability varied based on clinician experience. Sensitivity was 73.33% and 66.67% for the expert raters. Specificity was strong for all 3 clinicians (93.33%, 84.44%, and 91.11%). DISCUSSION: Neuromuscular ultrasound of the forearm is reliable and accurate for the diagnosis of IBM, although sensitivity was higher among experienced clinicians. Muscle Nerve 59:478-481, 2019.

Azathioprine-induced hypersensitivity reaction mimicking sepsis in a patient with systemic lupus erythematosus.

A 21-year-old woman with a history of systemic lupus erythematosus presented to the emergency department with acute-onset nausea, vomiting, and fevers. Two weeks prior, she was started on azathioprine 50 mg daily by her outpatient rheumatologist; the dose was up-titrated to 100 mg when repeat blood work showed no drug toxicity. The morning after increasing her dose, she was awoken by recurrent emesis. At presentation, she was febrile, tachycardic, and hypotensive. Her exam showed mild, generalised abdominal tenderness but was otherwise unremarkable. Lab work demonstrated elevated inflammatory markers, elevated liver transaminases, and stable hypocomplementemia. Chest X-ray and computed tomography abdomen/pelvis were unrevealing. She was given intravenous fluids and broad-spectrum antibiotics, and azathioprine was held. A thorough infectious workup returned negative. A flare of her systemic lupus erythematosus was considered but deemed an unlikely explanation of her systemic inflammatory response syndrome. With azathioprine discontinuation, she made a rapid, near-complete recovery within 24 h of admission, suggesting a diagnosis of azathioprine hypersensitivity syndrome. This case exemplifies the difficulty in distinguishing azathioprine hypersensitivity from mimickers such as infection and underlying autoimmune disease flare. Prompt recognition of hypersensitivity can lead to appropriate discontinuation of the drug and prevent future morbidity.