5. Isolated head drop: first symptom of anti-synthetase syndrome

Abstract

IntroductionHead drop is an unusual clinical manifestation of myositis or neuromuscular weakness, and typically requires extensive investigation to identify the underlying pathology. Case report data are limited on this topic.Case descriptionA 72-year-old man with a background of extractable nuclear antigen (ENA) negative mixed connective tissue disease, trigeminal neuralgia, interstitial nephritis and ischaemic heart disease presented with an isolated head drop. On further prompting, he confirmed mild shortness of breath on exertion. He had sclerodactyly but no features of mechanic’s hands. Serum creatinine kinase was 1398 IU/L. Electromyography was myelopathic. Muscle biopsy taken from the neck was inconclusive. He had a strongly positive anti-nuclear antibody (ANA) test, and borderline myositis ENA panel result with borderline positive anti-EJ antibody.The myositis panel result prompted further investigation for underlying interstitial lung disease. Pulmonary function testing revealed a restrictive picture, with KCO of 82%. High resolution computed tomography showed areas of fine interstitial fibrotic change in all lobes.He was treated with a reducing course of oral prednisolone and 15mg weekly oral methotrexate with an excellent clinical response, with resolution of the head drop and normalisation of serum CK value. Repeat pulmonary function testing remains stable after 5 months.DiscussionThis is an unusual presentation of presumed anti-synthetase syndrome. As methotrexate had already been prescribed before the underlying lung pathology was identified with resulting excellent clinical response and stable respiratory symptoms, a multi-disciplinary decision was made to continue with this choice of disease modifying agent. The decision to use methotrexate in the presence of interstitial fibrosis is always difficult, and requires close liaison between rheumatology and respiratory colleagues.Key learning pointsPositive anti-synthetase antibodies should prompt further investigation for underlying interstitial lung disease. Head drop can be a first symptom of autoimmune myositis and warrants further investigation.Conflicts of interestThe authors have declared no conflicts of interest.