Senior Resident Pediatric Allergy Immunology Unit, Department of Pediatrics, PGIMER, Chandigarh Chandigarh, Chandigarh, India
Background: Myositis in KD is an atypical manifestation which can lead to life-threatening complications if unrecognised. Objective of this case report is to highlight a case where laryngeal weakness was the presentation of myositis in KD.
Methods: An 18-month-old boy presented with acute febrile illness and redness of oral mucosa, tongue, and diffuse erythematous rash. He developed swelling of the dorsum of hands. Investigations showed anaemia (haemoglobin 79g/L), thrombocytopenia (platelet count 34x109/L, hyponatremia (129 mEq/L), hypoalbuminemia (29 g/L) and elevated CRP 36mg/L. 2D ECHO showed normal CA and good myocardial function. Based on the constellation of clinical features, a diagnosis of complete KD was proffered, and he was treated with IVIG (2g/kg) and aspirin (at 3mg/kg/day) on day 9 of illness. He had prompt defervescence of fever, and normalisation of inflammatory parameters.He later developed periungual peeling. However, he developed difficulty in getting up from sitting position, progressive aphonia with frequent coughing during deglutition on day 12. Nervous system examination revealed reduced power of both proximal lower limbs (LL) (grade 2/5) with normal deep tendon reflexes and cranial nerve examination. A vocal cord ultrasonogram (USG) showed equal movement of the vocal cord from the midline on both sides, ruling out recurrent laryngeal nerve palsy. Creatine kinase (CK) level was significantly increased (4155 U/L). With these features, the diagnosis of KD with myositis causing laryngeal weakness and LL proximal muscles was considered. He was given methylprednisolone pulse (30mg/kg/day), followed by tapering doses of oral prednisolone. Over the next 48 hours, he showed significant improvement in muscle weakness along with improvement in aphonia and normalized voice intensity.
Results: The onset of muscle weakness followed the diagnosis of KD in 78% of reported patients (36 hours to 35 days), like the index patient where myositis occurred after treatment of acute phase. The severity of weakness is proportionate to the muscle enzyme levels.
Conclusion: Myositis in KD causing laryngeal muscle weakness is rare, only the second to be reported and can be life-threatening. It underscores that even after prompt diagnosis and treatment, close clinical monitoring through the subacute phase is necessary to detect potential myositis.
