Study of some "intrinsic risk factors" that can enhance an iatrogenic injury of the external branch of the superior laryngeal nerve

OBJECTIVE: This study evaluates some "intrinsic risk factors" for a surgical injury of the external branch of superior laryngeal nerve (EBSLN) based on its anatomic relationship with the thyroid gland. STUDY DESIGN AND SETTING: Seventy-two neck dissections were performed in 36 fresh human adult cadavers. Every EBSLN was dissected and categorized using Cernea's classification. All data regarding gender, ethnicity, stature, side of the neck, and volume of hemi thyroid were collected and statistically analyzed by the chi(2)-test and analysis of variance. RESULTS. Although no statistical differences were observed between genders (P = 0.3770), ethnicities (P = 0.9780) or sides of the neck (P = 0.2523), statistical significance was reached regarding the nerve type when the groups were divided by stature (P = 0.0006) and glandular volume (P = 0.0007). CONCLUSION: Individual stature and volume of the hemi thyroid gland are probably involved in risk of the surgical EBSLN injury. SIGNIFICANCE: Surgeons should be aware of these anatomic findings in order to obtain a good voice-related outcome in the thyroidectomies.