HEMI-LARYNGECTOMY
This operation is suitable for certain cases of malignant disease which is strictly limited to one half of the larynx. The requirements and first and second stages of the operation are similar to those for thyrotomy (see [pp. 490], [491]).
Third stage. A transverse incision is made on the side affected along the upper border of the thyreoid cartilage, through the skin and fasciæ; and, if necessary, a second transverse incision is made at the level of the lower border of the cricoid so that a skin flap can be turned back. The affected half of the larynx must now be considered as a tumour to be removed. The infrahyoid muscles are dissected away from the ‘tumour’ and retracted; the upper part of the lateral lobe of the thyreoid gland (the isthmus having been previously divided) is displaced outwards by blunt dissection, and the soft tissues above the thyreoid are similarly treated: the larynx should be pulled well over to the opposite side while this is being effected, great care being necessary to avoid wounding the carotid artery in the deeper part of the dissection. The branches of the superior thyreoid artery, the crico-thyreoid artery, and the veins of this region are ligatured with catgut. In some instances, when the growth has not perforated the cartilage, the separation can be performed subperiosteally. Superiorly, the thyreo-hyoid membrane is completely divided on the same side, and the mucosa is cut through above the upper limit of the growth. If the growth extends upwards, the epiglottis may be removed either totally or partially. Inferiorly, a transverse incision must be made through the crico-thyreoid or crico-tracheal membrane, or lower in the trachea. The inferior constrictor of the pharynx is divided as close to the attachment to the thyreoid as possible, and the cavity of the pharynx is opened behind the growth. The cricoid plate is split with bone scissors in the interarytenoid interval, and the final attachments are rapidly divided with a few touches of the knife.
In this operation, as with other operations for cancer, the main thought of the surgeon must be to remove the tumour thoroughly, including the soft tissues of the neck when these are diseased, the lateral wall of the pharynx, and the cervical glands upon the same side, whether they are known to be affected or not. In this respect the operation differs materially from thyrotomy; and I agree with Semon that, if hemi-laryngectomy is necessary, the lymphatic glands of the same side should in all cases be removed. The two dissections may be accomplished at the same time, or one may be performed later at a second operation; in the latter event an incision along the anterior border of the sterno-mastoid muscle is preferred. The operation must be very complete in order to be successful, and requires a knowledge of the anatomy of the lymphatics.
THE ANATOMY OF THE LARYNGEAL LYMPHATICS.
The following description is Cuneo’s[14] and has been confirmed by de Santi.[15]
The lymphatics which drain the mucous membrane of the larynx are divided into two distinct regions, namely, the supraglottic and the infraglottic zones. These regions are separated by the inferior vocal cords, and injection of the cords themselves generally passes into the upper zone. The upper region is most densely supplied, and covers the epiglottis, the aryteno-epiglottidean folds, the superior vocal cords, and the ventricles.
The lymphatics communicate freely in the posterior wall of the larynx (not in the anterior commissure), but though an injection into one half of the larynx easily passes into the mucous membrane of the other side, it is exceptional for it to pass as far as the corresponding glands of that side. The lymphatics of the larynx anastomose to a large extent with the networks of the adjacent organs (tongue, pharynx, trachea).
The supraglottic lymphatics perforate the thyreo-hyoid membrane where the superior laryngeal arteries enter, and end in (1) a substerno-mastoid gland under the posterior belly of the digastric; (2) glands on the internal jugular vein opposite the bifurcation of the carotid artery; and (3) glands on the same vein opposite the middle of the lateral lobes of the thyreoid gland. The glands in the front of the thyreo-hyoid membrane receive lymphatics from the pharynx, but none from the larynx.