title: A study of muscle involvement in scrub typhus.
abstract: OBJECTIVE
  Patients with scrub typhus often complain of myalgia, but a comprehensive study on muscle dysfunction is lacking. We therefore report the clinical, electromyographic and muscle biopsy findings in patients with scrub typhus.
  
  
  METHODS
  Consecutive patients with scrub typhus were included, and their clinical and laboratory findings were noted. The patients with myalgia or weakness and elevated serum creatine kinase (CK) were considered to have muscle involvement. Electromyography (EMG) and muscle biopsy were done in some patients. Patients were treated with doxycycline 200mg daily for 7 days, and their clinical and biochemical outcome on discharge and one month were evaluated.
  
  
  RESULTS
  13 out of 33 (39.4%) patients had muscle involvement and their CK levels ranged between 287 and 3166 (859 ± 829) U/L. EMG revealed short duration polyphasic potentials, and muscle histopathology revealed evidence of vasculitis. There were significant correlations between severity of weakness and CK levels (r = -0.6; p < 0.001), platelet counts (r = 0.4; p = 0.04), duration of illness (r = -0.4; p = 0.01) and disability on discharge (r = -0.4; p = 0.04). Patients with muscle involvement had more severe illness evidenced by a lower Glasgow Coma Scale score (p < 0.001), thrombocytopenia (p = 0.05) and greater disability on discharge (p = 0.007), when compared to those without muscle involvement. All the patients had complete recovery following doxycycline therapy, and CK levels also normalized.
  
  
  CONCLUSIONS
  Muscle dysfunction was present in 39% patients with scrub typhus. Although muscle histopathology showed evidence of vasculitis, patients responded to doxycycline.
authors.affiliation: Department of Neurology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, India.
authors.forename: Jayantee
authors.initials: J
authors.lastname: Kalita
authors.affiliation: Department of Neurology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, India. Electronic address: drukmisra@rediffmail.com.
authors.forename: Usha K
authors.initials: UK
authors.lastname: Misra
authors.affiliation: Department of Neurology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, India.
authors.forename: Vinita E
authors.initials: VE
authors.lastname: Mani
authors.affiliation: Department of Neuropathology, National Institute of Mental Health and Neuro Sciences, Bangalore, India.
authors.forename: Anita
authors.initials: A
authors.lastname: Mahadevan
authors.affiliation: Department of Neuropathology, National Institute of Mental Health and Neuro Sciences, Bangalore, India.
authors.forename: Susrala K
authors.initials: SK
authors.lastname: Shankar
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology*; D003402:Creatine Kinase / Q000097:blood*; D004318:Doxycycline / Q000008:administration & dosage / Q000494:pharmacology; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology*; D063806:Myalgia / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology*; D012612:Scrub Typhus / Q000150:complications* / Q000175:diagnosis / Q000188:drug therapy; D012720:Severity of Illness Index; D016896:Treatment Outcome; D014657:Vasculitis / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology*; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D003402:Creatine Kinase; D004318:Doxycycline
keywords: Creatinine kinase; Electromyography; Histopathology; Myopathy; Scrub typhus; Vasculitis