The
surgery was described and pioneered by Isshiki
of Japan and is also called as medialization
thyroplasty. The procedure essentially involves
medializing the paralysed cord and keeping it
in place with the help of a silastic block.
The procedure is surprisingly simple and can
be done under local anaesthesia. A transverse
incision of 4 cms is put at the region of the
Thyroid prominence from the midline to the anterior
border of Sternocleidomastoid muscle. Subplatysmal
flaps are elevated and the Strap muscles are
retracted. A window is cut in the laryngeal
cartilage to a size determined by Koufman's
formula or ½ to ½ rule of Peakwoo.
A prefabricated silastic block of optimum size
is inserted and kept in place after getting
a satisfactory voice. The functional result
can be improved with the addition of an Arytenoid
adduction technique.
Isshiki
had also described other variants of thyroplasty
which are not as commonly done as type 1 procedure.
It
is also called as lateralization thyroplasty.
It is done for cases of Spasmodic dysphonia where
the patient's vocal cords go into spasm whenever
he tries to speak. Here the vocal cords are divided
at the anterior commisure and separated by a piece
of cartilage or silastic.
This
procedure is done for cases of Puberphonia. Here
the vocal cords are apparently shortened by removing
vertical strips of thyroid cartilage.
This surgery
is done for Androphonia in females. Here the cords
are apparently lengthened by approximating the
cricoid ring to the thyroid lamina anteriorly