Botulinum Toxin A in Patients With Myofascial Pain Syndrome With and Without Zinc Supplementation

Myofascial pain syndrome is a complex disorder of the musculoskeletal system with multifactorial involvement and diverse clinical presentations in several areas of the body It can affect the oro-cranio-facial region, with involvement of the temporomandibular area and masticatory muscles, and is then called myofascial pain dysfunction syndrome. Botulinum injections can improve blood flow to the muscles and release the nerve fibers compressed by abnormally contracting muscles, both of which may contribute to the cause of pain. In addition, botulinum injections can have an immediate effect owing to direct release of endogenous endorphins from introduction of the needle and alteration in the balance of central neurotransmitters; this is caused by local inhibition of pain peptides from sensory ganglions and nerve terminals, and anti-inflammatory and antiglutaminergic actions . Moreover, studies have shown that 3-10% of patients develop neutralizing antibodies with long-term adverse effects that include muscular atrophy. BTX clinical efficiency and duration varies according to the zinc levels of the patient. Although the BTX effect could remain for several months, its zinc-dependent proteolytic activity befalls within hours of administration before the toxins are degraded in the tissues. Therefore, for achieving better results from BTX, the recipients should have adequate zinc levels at the time of administration. Therefore, oral zinc supplement intake prior to BTXA injection may enhance its clinical efficiency and duration. Explanation for choice of comparators: BTX is offered as a solution for myofascial pain patients; nevertheless, it is not considered as a definitive long-term solution so we add the zinc supplementation prior to BTXA injection to increase the clinical duration as reviewed in literature review.