Use of botulinum toxin type A in symptomatic accessory soleus muscle: first five cases

Symptomatic accessory soleus muscle (ASM) can cause exercise‐induced leg pain due to local nerve/vascular compression, muscle spasm, or local compartment syndrome. As intramuscular injections of botulinum toxin type A (BTX‐A) can reduce muscle tone and mass, we investigated whether local BTX‐A injections relieve the pain associated with symptomatic ASM. We describe five patients presenting peri/retromalleolar exertional pain and a contractile muscle mass in the painful region. Com‐pression neuropathy was ruled out by electromyo‐graphic analysis of the lower limb muscles. Doppler ultrasonography was normal, excluding a local vascular compression. ASM was confirmed by magnetic resonance imaging. After a treadmill stress test, abnormal intramuscular pressure values in the ASM, confirmed the diagnosis of compartment syndrome only in one patient. All five patients received BTX‐A injections in two points of the ASM. The treatment efficacy was evaluated based on the disappearance of exercise‐induced pain and the resumption of normal physical and sports activities. After BTX‐A injection, exertional pain disappeared and all five patients resumed their normal level of physical and sports performances. Neither side effects nor motor deficits were observed. BTX‐A is well tolerated in patients with ASM and could be used as a new conservative therapeutic strategy for the treatment of symptomatic ASM before surgery.