Doxorubicin chemomyectomy is a potent method for the permanent removal of a muscle or group of muscles after direct local injection, and has been used successfully to treat
blepharospasm and
hemifacial spasm patients. The efficacy of
doxorubicin chemomyectomy on reducing muscle strength after direct injection of
doxorubicin into rabbit sternocleidomastoid muscle was tested. One- and 6-month postinjection force assessment was performed in vitro to measure alterations in peak twitch and tetanic force generation, as well as
fatigue responses for the treated muscles compared to control. There were significant reductions of both twitch and tetanic peak amplitudes in the
doxorubicin-treated muscles. One month
after treatment, the decreases in force were greater after 2 mg
doxorubicin injections than after 1 mg
doxorubicin. While there was a significant reduction in force generation after
doxorubicin treatment,
fatigue resistances for the
doxorubicin-treated muscles were increased compared to the controls. There were significant reductions in muscle mass after
doxorubicin treatment, and by 6 months, the
myosin heavy chain isoform distribution was similar to normal sternocleidomastoid, except for an increase in slow
myosin-positive fibers.
Doxorubicin chemomyectomy resulted in a significant reduction in functional force generation in the treated sternocleidomastoid muscles. These findings suggest a potential clinical use of
doxorubicin chemomyectomy to treat
cervical dystonia patients.