Benign acute childhood myositis: Difference between revisions

'''Benign acute childhood myositis''' (BACM) is a syndrome characterized by muscle weakness and pain ofin the lower limbs that develop in children after a recent viral illness. It is transient with a spontaneous clinical resolution within 1 week.<ref name=brisca>{{cite journal|vauthors=Brisca G, Mariani M, Pirlo D, et al |title=Management and outcome of benign acute childhood myositis in pediatric emergency department|journal=Italian Journal of Pediatrics |volume=47 |issue=1 |pages=307–317 |date=2021 |doi=10.1186/s13052-021-01002-x |pmid=123455|33750449s2cid=232146322 |pmc=7945053 |doi-access=free }}</ref><ref name=azevedo>{{pmidcite journal|vauthors=Costa Azevedo A, ((Costa E Silva A)), Juliana Silva C, Poço Miranda S, Costa M, Martinho I |title=Benign acute childhood myositis: A 5-year retrospective study|journal=Arch Pediatr |volume=29 |issue=7 |pages=490–493 |date=2022 |doi=10.1016/j.arcped.2022.08.009 |pmid=36109287|s2cid=252242350 }}</ref>

Affected are pre-schoolpreschool and school-age children with a male predominance.<ref name=azevedo/> In one study, the median age was 6 years (range 2-132–13.2 years).<ref name=brisca/> It has been estimated that BACM has an incidence of 2.69 cases per 100,000 children (<18 years) during epidemic seasons and 0.23 cases during non-epidemic seasons.<ref>{{pmidcite journal|vauthors= Buss BF, Shinde VM, Safranek TJ, Uyeki TM| title= Pediatric influenza-associated myositis - Nebraska, 2001-2007. |journal=Influenza Other Respir Viruses| year=2009 |volume=3 |issue=6| pages=277–85| doi=10.1111/j.1750-2659.2009.00102.x| pmid=19903210 | pmc= 4941392 }}</ref>

The history of a preceding influenza-like infection followed by the typical symptoms of acute onset of symmetrical calf pain and gait problems together with an isolated finding of a high level of [[creatine kinase]] suggests the diagnosis of BACM.<ref name=chu>{{pmidcite journal| vauthors=Chu EC, Yip AS| title= A rare presentation of benign acute childhood myositis |journal=Clin Case Rep |year=2019 |volume=7 |issue=3 |pages=461–464 |doi=10.1002/ccr3.2001 |pmid=30899472| pmc= 6406135 }}</ref> [[Myoglobinuria]] is rare and points to the possibility of the development of rhabdomyolysis and kidney failure.<ref name=azevedo/><ref name=cassim>{{cite journal|vauthors=Cassim F, Soni AJ, Murphy S|title=Severe acute inflammatory myositis and rhabdomyolysis in paediatric SARS-CoV-2-associated MIS-C (multisystem inflammatory syndrome in children)|journal=BMJ Case Reports|volume=14 |issue=8|year=2021|pages=e243112 |doi=10.1136/bcr-2021-243112|pmid=34373240|pmc=8354289 }}</ref>

[[Guillain-BarreBarré syndrome]] (GBS) is the main consideration in the differential diagnosis. It needs to be quickly excluded as early intervention in GBS is indicated. Other conditions under possible consideration are [[dermatomyositis]], [[muscular dystrophy]], [[juvenile idiopathic arthritis]], [[transient synovitis of the hip]], [[osteomyelitis]], and [[myalgia]].<ref name=brisca/>

A number of different preceding viral infections have been reported, most commonly [[influenza A]] and [[influenza B|B]]. The condition appears to be more prevalent during late fall, winter, and spring.<ref name=azevedo/> Other virus infections that have been linked to BACM are those caused by [[Parainfluenza]], Cocksackievirus[[Coxsackievirus]], [[Adenovirus]], [[Echovirus]], and [[Mycoplasma pneumonia]].<ref name=brisca/>

in 1957 Lundberg reported on a group of patients with a condition he named ''myalgia cruris epidemica'',<ref>{{pmidcite journal| author=Lundberg A |title= Myalgia cruris epidemica |journal= Acta Paediatr (Stockh)| year=1957| volume=46 |issue=1 |pages=18–31| doi=10.1111/j.1651-2227.1957.tb08627.x |pmid=13410584|s2cid= 6590371 }}</ref>, seemingly the first description of BACM. Other terms later used include ''influenza-associated myositis, viral myositis, acute myositis''<ref name=azevedo/> Middleton and colleagues reported on BACM as ''severe myositis after influenza'' in 1970.<ref>{{pmidcite journal |vauthors=Middleton PJ, Alexander RM, Szymanski MT| title=Severe myositis during recovery from influenza |journal= Lancet |year=1970 |volume=2| issue=7672 |pages=533–5 |doi= 10.1016/s0140-6736(70)91343-7| pmid=4195201}}</ref> Viral myositis may occur also in later years.

[[Category: Inflammations]]

[[Category: Muscular disorders]]