The investigators hypothesize that Botox A will reduce scarring and improve healing of surgical neck wounds.

Botulinum Toxin A is a toxin produced by the anaerobic bacterial species Clostridium botulinum. The toxin specifically inhibits release of the neurotransmitter Acetylcholine at synaptic junctions, thus preventing neuromuscular transmission, and inducing paralysis of the muscle.

Previous studies have indicated that tensile forces on the skin may affect the healing of a wound. These forces act against the immature collagen laid down during wound healing and may stimulate overgrowth, thereby contributing to the formation of hypertrophic scars or keloids.

Using botox to paralyse the underlying muscles may reduce the tensile force on the overlying skin, and thus reduce scar formation and promote healing. Botox has also been shown to affect the cell cycle distribution of fibroblasts derived from hypertrophic scars.

The objective of this study is to determine the effects of BTX-A in wound healing and the reduction of scar formation.

Patients undergoing a thyroidectomy or parathyroidectomy will be randomized to receive either BTX-A injections along the surgical site or placebo immediately following closure. All incisions will be sutured in a similar fashion. BTX-A or normal saline will then be injected along the platysma muscle. The patient and the surgeon will be blinded to the treatment arm. Photographs will be taken of the surgical site at 4 weeks and 6 months. The patient and two otolaryngologists will independently score the healing of the wound using a standardized scoring method. The scores be compared between the two surgeons to determine correspondence and interobserver reliability.

The scores of the two treatment arms will be compared to reveal the effect of BTX-A on wound healing.

Inclusion Criteria:

• all patients referred to the ENT clinic for a thyroidectomy or parathyroidectomy

Exclusion Criteria:

• patients with missing information, including demographic information
• patients lost to follow up or have been followed for less than 6 months
• patients with known allergy to lidocaine
• patients in whom botox would be contraindicated in:
• known history of neuromuscular disorders (myasthenia gravis, amyotrophic lateral sclerosis, Eaton-Lambert syndrome)
• pregnant women
• known allergy to botox, albumin