In type 4 thyroplasty, vocal cord is

Thyroplasty Isshiki divided thyroplasty procedures into 4 categories to produce a functional alteration of vocal cords. Type I: It is medial displacement of vocal cord as in achieved in Teflon paste injection. Type II: It is lateral displacement of the vocal cord and is used to improve the airway. Type III: It is used to shoen the vocal cord. Relaxation of vocal cord lowers the pitch. This procedure is done in mutational falsetto or in those who have undergone gender transformation from female to male. Type IV: This procedure is used to lengthen the vocal cord and elevate the pitch. It conves the male character of the voice to female and has been used in gender transformation. It is also used when the vocal cord is lax and bowing due to the ageing process or trauma. Ref: Textbook of diseases of ENT, PL Dhingra, 7th edition, pg no. 340,341