Journal of Integrated Health Sciences

: 2019  |  Volume : 7  |  Issue : 2  |  Page : 56--60

An outbreak of acute viral myositis with different outcomes: A case series

Divya Goel, Arvind Vyas, Naveen Seervi 
 Department of Neurology, SMS Hospital, Jaipur, Rajasthan, India

Correspondence Address:
Dr. Divya Goel
4Ba19, Jawahar Nagar, Jaipur - 302 004, Rajasthan


Viral myositis is induced by direct muscle invasion, molecular mimicry, production of immune complexes, immune dysregulation, and various other mechanisms. The pathogenesis of this entity is still unclear. Here, we report a case series of viral myositis with varied clinical presentations who had different outcomes ranging from complete recovery to death. To report a variety of clinical and laboratory presentation of an outbreak of viral myositis. This was a case series of seven patients, describing clinical, electrophysiological, and laboratory tests and histopathology and treatment results. The study showed a benign course in 2, recurrence in 1, fulminant necrotizing myositis in 4, and coexisting Guillain–Barre syndrome in 2 with 1 patient culminating to death in the latter group. The variability in outcome of viral myositis suggests that there are some genetic factors which lead to fulminant necrotizing myositis in contrast to the patients experiencing a benign course of myositis.

How to cite this article:
Goel D, Vyas A, Seervi N. An outbreak of acute viral myositis with different outcomes: A case series.J Integr Health Sci 2019;7:56-60

How to cite this URL:
Goel D, Vyas A, Seervi N. An outbreak of acute viral myositis with different outcomes: A case series. J Integr Health Sci [serial online] 2019 [cited 2020 Jul 6 ];7:56-60
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Acute viral myositis manifests as muscle weakness, impairment in ambulation with tender and swollen muscles, especially in calves and thighs. It manifests mostly in children with a male predominance.[1],[2],[3],[4] The exact incidence is unexplored, but it is known to occur frequently in season of influenza outbreak. The symptoms preceding muscle weakness commonly include fever, malaise, cough, rhinorrhea, and odynophagia. The clinical manifestations have mostly been reported to be transient and self-limiting. However, potential dangerous complications in the form of myoglobinuria, renal shutdown, cardiac arrhythmias, and compartment syndrome may occur and are associated with significant morbidity and mortality.[5] Here, we report an outbreak of acute viral myositis in October–November affecting adult age group with diverse clinical presentations and varied outcomes, thus highlighting the importance of keeping a high index of suspicion for development of complications and early intervention.

Aims and objectives

To report the diversity of clinical and laboratory presentation of an outbreak of viral myositis ranging from benign to fulminantTo report the coexistence of acute viral myositis with Guillain–Barre syndrome (GBS).

 Subjects And Methods

A case series of seven patients of acute viral myositis was taken in the period of October–November 2018, describing clinical, electrophysiological, and laboratory tests and histopathology and treatment results in SMS Medical College and Hospital, Jaipur.


Prior informed consent was taken from the patients recruited in the study.


Case 1

A 21-year-old male presented with febrile illness of 7-day duration followed by the development of myalgias and swelling both forearms associated with mild weakness of all four limbs. On examination, power was 4/5 in all proximal muscles, and muscle tenderness was present. Reflexes and sensory examination was normal. The systemic examination for other systems did not reveal any abnormality. His serum creatine phosphokinase (CPK-NAC) was 8320 IU/L at admission. Serum bilirubin, serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), and lactate dehydrogenase (LDH) were 2.6 mg/dl, 70 IU/L, 182 IU/L, and 1660 IU/L, respectively. Nerve conduction studies (NCSs) were normal. Electromyography (EMG) showed the presence of normal amplitude motor unit action potentials with early recruitment. No spontaneous activity was observed. A muscle biopsy was taken to distinguish viral versus autoimmune process from right quadriceps muscle which showed inflammation of muscle fibers with necrosis. Detailed immunologic screening for connective tissue disorder yielded negative results. He was started on iv methylprednisolone pulse therapy at a dose of 1 g/day for 5 days with supportive treatment in the form of adequate hydration with iv fluids. The patient started showing improvement on the 2nd day of admission evidenced by decrease in myalgias, swelling, and serum CPK. His CPK gradually fell down to 1120 IU/L on the 5th day of therapy. He was discharged in a stable condition on oral steroids (tablet prednisolone 1 mg/kg), and azathioprine 50 mg/day was added in view of suspected underlying autoimmune mechanism. Steroids were tapered off gradually and tablet azathioprine was built up to 150 mg/day in next 3 months.

Case 2

A 48-year-old diabetic, hypertensive male presented with fever of 2 days followed by progressive weakness of all four limbs of subacute onset for a month. There were associated myalgias and swelling of muscles. Examination suggested flaccid quadriparesis with hyporeflexia, normal sensory examination, and vitals. Nerve conduction study and EMG did not show any abnormalities. The CPK levels at admission were 9940 IU/L with derangements in SGOT (84 IU/L), SGPT (184 IU/L), and LDH (1291 IU/L). His muscle biopsy was sent. Considering it as polymyositis, he was started on intravenous immunoglobulin (ivIg) at 2 g/kg divided over 5 days. On day 3 of admission, he showed deterioration in the form of increased swelling and tenderness of muscles with corresponding increase in CPK to 15520 IU/L. His magnetic resonance imaging (MRI) forearm was carried out to rule out any abscess formation in view of the nonresponse and intense edema he had developed on his forearms. MRI [Figure 1] was suggestive of changes of myositis and cellulitis. Muscle biopsy report was suggestive of necrosis with mild inflammatory changes. He could not be subjected to genetic testing for anti-SRP antibodies and anti-HMG CoA reductase antibodies due to nonavailability of the tests. Keeping the possibility of autoimmune mechanism coexisting with the viral pathology, he was started aggressively on iv antibiotics and pulse therapy of steroids (injection methylprednisolone 1 g/day × 5 days). He responded well within the next 2 days and his general condition improved. He was discharged on the 7th day with CPK fallen to 500 IU/L on oral steroids (tablet prednisolone 1 mg/kg) and antibiotics.{Figure 1}

Case 3

A 32 -year-old male presented with acute onset weakness of all four limbs with severe pain preceded by a history of fever 10 days back. Currently, he was afebrile, had power of 4/5 in all limbs with normal reflexes, sensations, and systemic examination. His electrophysiological studies were normal. CPK was raised (7760 IU/L). His muscle biopsy was carried out to confirm viral versus autoimmune process, and in the meantime, he was started on iv steroids (injection methylprednisolone 1 g/day × 5 days). Connective tissue screening results were negative. He improved within next 4 days and was discharged on tablet prednisolone 1 mg/kg. After 1 month, he came back with increased weakness, this time more in his upper limbs with severe myalgias not associated with fever. His CPK this time was 1560 IU/L. His muscle biopsy report was suggestive of inflammation and necrosis. He was this time given iv antibiotics and continued on oral steroids. Tablet azathioprine 50 mg/day was added along with. He improved within next 5 days and discharged uneventfully. Tablet prednisolone was tapered off and tablet azathioprine was built up to 150 mg/day in next 3 months. He was then maintained on tablet prednisolone 5 mg/day and tablet azathioprine 150 mg/day without any relapse on follow-up.

Case 4

A 46-year-old diabetic male presented with fever along with diffuse severe muscle pains. This was followed by the development of weakness of all four limbs with pain persisting over the next 15 days associated with passage of red-colored urine for 2 days. The patient suffered respiratory compromise with respiratory rate of 2/min. On examination, he had an areflexic lower motor neuron (LMN) quadriparesis with respiratory compromise. His blood biochemistry showed CPK level of 4120 IU/L on admission which increased to 11350 IU/L the next day, SGOT of 843 IU/L, and SGPT of 347 IU/L with total leukocyte count of 15,000 with predominant neutrophils. He had nonketotic hyperglycemia and his urine tested positive for myoglobin. His nerve conduction study showed sensorimotor axonal affection of tested nerves. EMG was suggestive of myopathic pattern. He was on oxygen support at 4 L/min, iv antibiotics, fluids, ivIg, and iv methylprednisolone. Despite the aggression shown in management, his urine output decreased with development of acute tubular necrosis and the patient left against medical advice.

Case 5

A 38-year-old diabetic male presented with LMN type of quadriparesis with preceding fever 15 days back. There were associated severe muscle aches and swelling of muscles. There was no bulbar or respiratory compromise along with. On examination, tenderness and edema was present and power was 3/5 in all four limbs with areflexia. Nerve conduction study revealed predominantly demyelinating sensorimotor affection of bilateral median, ulnar, tibial, and peroneal nerves. EMG was suggestive of myopathic pattern. CPK was 7220 IU, SGOT 80 IU/L, and SGPT 166 IU/L at admission. Urine was negative for myoglobin. Thus, the possibility of GBS with myositis was kept. He was started on ivIg 2 g/kg over 5 days along with high doses of injectable steroids (injection methylprednisolone 1 g/day) under the cover of broad-spectrum antibiotics. Initially, the patient remained status quo and CPK did not fluctuate much. However, on the 3rd day, his CPK rose to 34,500 IU with power in lower limbs deteriorating to 2/5. SGOT and SGPT simultaneously worsened to 520 IU/L and 230 IU/L. He developed skin blisters, but still was afebrile. In lieu of the clinical worsening, an autoimmune mechanism was postulated and he was started on iv cyclophosphamide at a dose of 750 mg/m2 body surface area with iv Mesna. His genetic testing for autoimmune necrotizing myositis was planned, but could not be performed due to its nonavailability. His CPK level came down to 29,500 the other day, but to rise again to 34,000 IU the next day. The co-occurrence of GBS portended a bad prognostic marker for this patient. He was given a second trial of ivIg at a dose of 1 mg/kg over 5 days after an interval of 7 days from the first. Gradually, the patient showed improvement after 15 days and CPK fell down to 750 IU when he was discharged on oral steroids (tablet prednisolone 1 mg/kg) with iv cyclophosphamide 750 mg/m2 as pulse therapy monthly. The patient came for follow-up in next 2 months when his oral prednisolone was tapered off to 20 mg/day with monthly doses of injection cyclophosphamide.

Case 6

A 45-year-old diabetic female presented with a history of fever 2 weeks before admission lasting 7 days followed by LMN quadriparesis with respiratory and bulbar involvement. On examination, single breath count was 8 and power was 2/5 in upper and 05 in lower limbs with total areflexia. Extremities were edematous and tender. Her NCS showed demyelinating + axonal sensorimotor neuropathy with sural-sparing pattern. Her cerebrospinal fluid examination showed albuminocytological dissociation (cells <5, proteins = 63 mg/dl). Blood analysis showed CPK of 7730 IU, SGOT of 241 IU/L, and SGPT of 202 IU/L with leukocytosis. On the basis of mixed picture of GBS and myositis, she was started on ivIg, pulse steroid therapy, and broad-spectrum antibiotics. She was intubated the same day and maintained on volume control mode of ventilation. Her total leukocyte count raised to 26,000/cumm and CPK levels fell down to 4080 IU with minimal alteration in occupational therapy (OT) and physical therapy ( PT). The 3rd day, she had a drop in blood pressure for which she was started on inotropic support. Her CPK fell further to 1860 IU, OT 156, and PT 207 U/L. She suffered cardiopulmonary arrest the 4th day and succumbed to death, thus supporting that coexistence of viral myositis with GBS served as a grave prognostic marker.

Case 7

A 23-year-old male presented with fever 3 weeks before admission, proven as dengue IgM positive in a private hospital and treated in next 10 days followed by the development of weakness of all four limbs proximal > distal, swelling of muscles with severe pain all over the extremities for the last 4 days before admission. On examination, power was 3/5 in all limbs with deep tendon reflexes (DTRs) preserved and normal sensory examination. Blood analysis showed CPK of 7620 IU, OT 267 U/L, and PT 164 U/L. EMG showed myogenic pattern with normal nerve conduction study. His chest X-ray revealed mild pleural effusion and ultrasound abdomen showed mild ascites with abdominal wall edema. He was considered a case of viral myositis and treated with crystalloids and colloids. On the 2nd day, he showed deterioration in his power and respiratory status with rise in serum CPK to 28,100 IU. This deterioration was attributed to an underlying autoimmune process coexisting with the viral pathology. Thus, he was started on ivIg (2 g/kg over 5 days) and kept on low-flow oxygen at 2 L/min. He was given iv acetylcysteine 600 mg bd along with. Seeing his lack of improvement in next 2 days with rise of serum CPK to 38,000 IU, he was started on iv steroids 1 g/day. He showed marked improvement both clinically and biochemically with CPK falling to 16,390 IU within 2 days. He was discharged on the 12th day with CPK lowered down to 560 IU on oral prednisolone 1 mg/kg/day and azathioprine 50 mg/day. On follow-up after 3 months, tablet prednisolone was tapered off to 10 mg/day and azathioprine was built to 150 mg/day with no evidence of relapse.

[Table 1] shows the demographic features depicting the age, sex, and clinical features of the patients. There has been a male preponderance with predilection for young to middle aged patients. Three of them presented within a week from fever with muscle weakness and pain and four presented after a span of 10 days from fever. All cases presented with muscle weakness, myalgias, and edematous limbs. Three cases had dyspnea, two of them had association with GBS, suffering with dyspnea, and one succumbed to death.{Table 1}

[Table 2] shows the various treatment modalities used including ivIg, steroids, azathioprine, and cyclophosphamide.{Table 2}


In this case series, we describe the different outcomes of an outbreak of viral myositis in adults ranging from benign to fulminant. The rapid development of musculoskeletal symptoms, concomitant rise in creatine kinase, LDH, SGOT, SGPT muscle biopsy & imaging findings of inflammation and necrosis helped in clinching the diagnosis. Myositis can be caused by viral, bacterial, parasitic, and fungal infections.[6] Bacterial myositis, also termed pyomyositis, has severe disease evolution, but more frequently localized to single or few muscle groups. Parasitic infection of muscles is mostly accompanied with eosinophilia frequently producing calcified cysts on radiographs. Fungal invasion of muscles mostly have a predilection for immunocompromised individuals and have a more indolent course. Viral myositis, though mostly self-resolving in children, can present in a notorious manner in adults. There are many mechanisms which lead to myositis after viral infection including direct viral invasion, autoimmune mechanism, and molecular mimicry. Very few case reports have been described in literature accounting for the fulminant nature of viral myositis. It is highly likely that certain underlying genetic mechanisms prevail explaining the diverse clinical course of patients of viral myositis. A retrospective analysis of 42 children of acute viral myositis was carried out by Cardin et al.,[7] wherein musculoskeletal symptoms were localized pain in the calves (80%), limited ambulation (57%), gait abnormality (40%), and muscle weakness in the lower limbs (71%), along with significant increase in CPK enzymes (5507 ± 9180 U/L), LDH (827 ± 598 U/L), and aspartate aminotransferase (199 ± 245 U/L) were seen. The cases were attributed to the outbreak of influenza, and the myositis was self-limiting in 100% of cases. Gibson et al.[8] in a case series of three adult patients of acute viral myositis described acute onset of muscle weakness, pain, and tenderness during the recovery phase of the virus, laboratory abnormality of mildly to moderately elevated CK, and complete resolution occurring within 1 week. However, no particular case series have reported the fulminant nature that viral myositis can produce or the coexistence of acute viral myositis with GBS. This study shows that viral myositis can produce fulminant myositis of necrotizing type requiring urgent intervention with ivIg, steroids, and immunosuppressants. The coexistence of GBS with viral myositis in two of our cases highlights the fact that molecular mimicry may have some role to play in viral myositis too, and this coexistence serves as a grave prognostic marker in the patients.


We propose that there are some patients predisposed to necrotizing illness after viral infection due to their genetic makeup. Although the exact etiopathogenesis is yet unexplored, this study urges us to think of the underlying autoimmune mechanisms in addition to the viral pathology causing such variation in the outcome of viral myositis which is otherwise considered a benign illness.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.


1Zafeiriou DI, Katzos G, Gombakis N, Kontopoulos EE, Tsantali C. Clinical features, laboratory findings and differential diagnosis of benign acute childhood myositis. Acta Paediatr 2000;89:1493-4.
2King BA. Benign acute childhood myositis as a cause of failure to weight bear. J Paediatr Child Health 2003;39:378-80.
3Agyeman P, Duppenthaler A, Heininger U, Aebi C. Influenza-associated myositis in children. Infection 2004;32:199-203.
4Mujgan Sonmez F, Cakir M, Yayla S, Boz C. Benign acute child-hood myositis. Med Princ Pract 2004;13:227-9.
5Bagley WH, Yang H, Shah KH. Rhabdomyolysis. Intern Emerg Med 2007;2:210-8.
6Mall S, Buchholz U, Tibussek D, Jurke A, An der Heiden M, Diedrich S, et al. A large outbreak of influenza B-associated benign acute childhood myositis in Germany, 2007/2008. Pediatr Infect Dis J 2011;30:142-6.
7Cardin SP, Martin JG, Saad-Magalhães C. Clinical and laboratory description of a series of cases of acute viral myositis. J Pediatr (Rio J) 2015;91:442-7.
8Gibson SB, Majersik JJ, Smith AG, Bromberg MB. Three cases of acute myositis in adults following influenza-like illness during the H1N1 pandemic. J Neurosci Rural Pract 2013;4:51-4.