Plate 182

This operation is based on careful dissection of various tissue planes between the muscles, vessels, and thyroid gland. Some type of self-retaining retractor is inserted to hold apart the skin flaps. In the presence of a large thyroid gland that necessitates division of sternohyoid and sternothyroid muscles, it is advisable to free the anterior margins of the sternocleidomastoid muscles. The margins of these muscles run diagonally across the outer limits of the wound and can be identified easily. The incision is made into the fascia along the margins of the sternocleidomastoid muscle (Figure 10). The handle of the scalpel is used as a dissecting tool to develop the correct plane of cleavage between the sternocleidomastoid muscle and the outer boundaries of the sternothyroid muscle (Figures 11 and 12).

To avoid bleeding, a vertical incision is placed exactly in the midline of the neck between the sternohyoid muscles, extending from the thyroid notch to the level of the sternal notch. All bleeding points are controlled by the application of hemostats. The tissues on either side of the incision are lifted up so that the incision is not carried directly through into the thyroid gland (Figure 13). The blunt handle of the knife is inserted beneath the exposed sternohyoid muscles (Figures 14 and 15). At this point the loose fascia over the thyroid gland should be picked up with forceps and incised with the scalpel in order to develop a cleavage plane between the thyroid gland and the sternothyroid muscle (Figures 16, 17, and 18). This is one of the most important steps in a thyroidectomy. Many difficulties may be encountered unless the proper cleavage plane is entered at this time. When the fascia of the sternothyroid muscle has been completely incised and reflected, the blood vessels in the capsule of the thyroid gland are clearly visible (Figure 18). After the proper cleavage plane is developed, the sternohyoid and sternothyroid muscles are pulled outward from the thyroid gland by means of a retractor, so that any unusual blood vessel communication between the sternothyroid muscle and the thyroid gland can be clamped and ligated (Figure 18). Once the surgeon is working in the proper cleavage plane, the delivery of the gland may be facilitated by inserting the two forefingers side by side to the outer edge of the thyroid gland and separating them, thus freeing the gland without injuring blood vessels (Figures 19 and 20). If an effort is made to free the entire lateral surface of the gland by finger dissection, it must be remembered that in some instances the middle thyroid vein is quite large and may be torn accidentally by this maneuver, resulting in troublesome bleeding.

If the thyroid is only moderately enlarged, retraction of the prethyroid muscles forward and laterally by narrow retractors will give adequate exposure for the subsequent procedure; however, if the mass of thyroid tissue is large, it may be wiser to divide the prethyroid muscles between muscle clamps. There is no difficulty with healing or function after transverse incision of the prethyroid muscles if this is done in the upper third to avoid injury to the motor nerve supply. The freed margin of the sternocleidomastoid muscle on either side is retracted laterally to avoid its inclusion in the muscle clamp (Figures 20 and 21). The muscle clamps are applied over the surgeon's finger as a guide to avoid including any part of the contents of the carotid bundle. The muscle is divided between the clamps, and an incision is made upward and downward from the end of either clamp to facilitate the retraction of the divided muscles (Figure 21). If large anterior jugular veins are present, it is advisable first to ligate them with transfixing sutures of fine silk adjacent to the upper and lower clamps. The muscle clamps can then be lifted out of the wound and will not hinder the subsequent procedure. The muscles on the left side are similarly divided.

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