[MIM 147 421]

Prevalence 1/14,000 to 1/106. Slowly progressive idiopathic inflammatory muscle disease reaching mostly men older  than 50 years (H/F ratio: 2 to 3: 1) but can appear earlier.  HLA - DR3 and 8-1CMH antigens seem to produce a particular genetic susceptibility. There is no response to corticosteroid therapy.

Clinical picture:

-        painless muscle weakness and atrophy of  progressive onset

-        it first affects the lower limbs (quadriceps femoralis) and flexor muscles of the thumb

-        th disability worsens as the disease progresses: foot drop, later often wheelchair bound

-        approximately 50% of patients eventually suffer a bulbar attack which leads to a dysphagia with a risk of aspiration (surgery: myotomy of the cricopharyngeus)

-        respiratory impairment is rare but probably underestimated.

Mildly raised CPK levels. Anti-IBM-43 autoantibodies in 50% of cases.

Muscle biopsy: atrophic fibers, mononuclear cell infiltrates, non-eosinophilic cytoplasmic inclusions.

EMG: typical image of low intensity and short lasting action potentials.

Anesthetic implications:

check the presence and the importance of a possible  of bulbar (dysphagia?) or respiratory involvement; non-depolarizing myorelaxants have been used without problem (monitoring!) but succinylcholine seems to cause postoperative muscle weakness.

References : 

• Mortenson AR, Sprung J, Cavalcante AN, Watson JC, Weingarten TN.
  Inclusion body myositis and anesthesia: a case series.
  J Clin Anesth 2016; 31: 282-7.

Updated: March 2019