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Título

Case report: Bilateral Gastrocnemius Myositis Associated With Influenza-like Symptoms

RESUMO

Case report:
The patient is a 34 year old male of previous good health. It was his second day of symptoms when he went to the doctor complaining of headache, sore throat, body ache and fever. The oropharynx had a diffuse hyperemia and exudates at the tonsillar crypts. The patient was discharged with Amoxicillin for 7 days, symptomatic medication and diagnosed with acute tonsillitis.
Three days later he returned with loss of strength in arms and legs, also feeling better from the odynophagia and body pains. At the neurological examination nothing pathological was found just as the cranial CT. The patient was hospitalized and a lumbar puncture was performed, the liquor analysis had non pathological signs. All the laboratorial routine exams didn’t show any abnormalities.
On the second day of hospitalization an increase of the pain was noticed on bilateral calf muscles. Prednisone was initiated, 60mg/day, more exams were requested, and the discrepancy was on CPK levels (1.166,4) and ANF (anti-nuclear factor) titulation 1/160. The day after the patient was dismissed without any neurological deficits and complaints, the final diagnosis was bilateral gastrocnemius myositis.
Discussion:
Our case was probably an IAM (Influenza-Associated Myositis), that disease was defined as follows: Virologically proven influenza or influenza-like illness plus clinical evidence for localized myalgia plus elevation of serum creatine phosphokinase (CPK) or abnormal muscle biopsy. Acute myositis has been reported as an pediatric exclusive disease, normally with symptoms like painful oedema of leg muscles in the days following a viral illness. Calf muscles were the only muscles affected in the cases reported in the past. The incidence is higher in boys, muscle symptoms usually begin 3 days following influenza symptom onset, with pain in one or both calves and difficulty walking being the most common complaints. Among cases of IAM, in ⅔ of cases, the calf muscles were affected alone, and ⅓ of cases occurred in multiple muscular groups in addition to the calf muscles. Treatment is symptomatic, as myositis is self-limited, usually resolving within a mean of 3 days.
Final comments:
Our case of IAM behaved differently from previous published reports, specially because of the age of the patient reported. So, it is a study that expands the definition for the general population, being not an exclusive pediatric disease and should be on the list of differential diagnosis on muscular disorders.

Palavras Chave

Influenza, Myositis