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236 Neck: Cysts, Sinuses, and Fistulas

1. The fistula is traced along the carotid sheath through the bifurcation
of the carotid artery, then medially to the tonsilla fossa.
2. The anaesthetist may assist by inserting a gloved finger into the
patient’s mouth to push the tongue down.
3. Another skin incision may be necessary, as a step-ladder incision, if
the original skin incision is too far down in the neck.
Patients with bilateral fistulas can have both sides operated at the
same sitting.
Histologically, the cysts are lined by squamous epithelium,
surrounded by muscle fibres and lymphoid tissue, but in 10% of
patients, respiratory columnar epithelium may also be present. 4,10
Third Branchial Arch
Embryology
The three pharyngeal arches and four pharyngeal pouches develop by
Source: Welch KJ, Randolph JG, Ravitch MM, O’Neill JA Jr, Rowe MI. Pediatric Surgery. Year the 27th day of embryonic life. The pouches are tube-like extensions
Book Medical Publishers, 1986. Used by permission. of the pharynx. 11
Figure 36.4: Courses of first, second, and third branchial fistulas.
The third arch mesenchyme forms the posterior one-third of the
tongue. Its cartilage ossifies to form the lower part of the hyoid
bone. Its only muscle, the stylopharyngeus, is supplied by the
glossopharyngeal nerve from the nucleus ambiguous. The thymus and
3
inferior parathyroid glands develop from the third pharyngeal pouch.
Differentiation of the third branchial arch is shown below:
• Skin: lateral part of neck
• Bone: lower part of body and greater horn of hyoid bone
• Muscle: superior pharyngeal constrictor
• Nerve: glossopharyngeal
• Artery: common carotid
• Membrane: lower part of pharynx
Remnants
Figure 36.5: Second branchial cyst in a 4-year-old girl (the cyst had Rarely, some cysts may arise from the left side of the neck in close
discharged and healed 4 or 5 times).
relation to the thyroid gland. The external openings are usually at the
anterior border of the clavicular head of the sternomastoid. The tract
For the procedures outlined below, a sandbag is placed under the shoul- runs behind the internal carotid artery, the vagus, and the hypoglossal
ders to extend the neck, and a head-ring is applied to steady the head, and superior laryngeal nerves, and then turns medially above the spinal
similar to the standard draping for a thyroid operation. The head is then accessory nerve and penetrates the thyroid membrane to end in the
turned to the contralateral side as convenient. pyriform sinus.
Brachial cysts Management
1. In branchial cysts, a transverse incision is made 3–4 cm long over Incision and drainage may be necessary when the cysts are infected.
the mass. The tract may need excision if there is recurrent infection.
2. The skin and platysma are incised and deepened to the edge of the mass. Histologically, thyroid, thymic, and lymphoid tissue and Hassall
corpuscles have been seen, which may suggest their origin from lower
3. Blunt and sharp dissections are done to identify the tract. It is 4
important to maintain a bloodless field, using mostly diathermy, pharyngeal pouches.
throughout the dissection and to keep close to the tract. Keeping close Fourth to Sixth Branchial Arches
to the tract will not only make the tract easily visible, but will prevent The fourth and sixth arches mingle as they produce the cartilages and
inadvertently injuring surrounding structures. It is not necessary to ligaments of the larynx, the levator palate, and the intrinsic muscles of the
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identify all the surrounding structures. If the dissection is very close to larynx and pharynx, all supplied by the vagus nerve. Part of thymus and
the tract, the likelihood of injuring other structures is slim. the superior parathyroid glands develop from the fourth pharyngeal pouch.
Sinus Contributions of the fourth branchial arch are shown below:
Preparation and draping for surgery is as above. • Skin: none
1. An elliptical incision is made around the opening.
• Cartilage: thyroid and arytenoids
2. The incision is deepened through the skin and platysma and the tract
• Muscles: inferior pharyngeal constrictor, cricothyroid, intrinsic laryngeal
is identified.
3. The operation then proceeds the same way as for removal of a • Nerve: superior laryngeal branch of vagus
branchial cyst. • Artery: arch of aorta on left side, first part of subclavian artery on right
Fistula side
In many cysts and sinuses, the tracts end blindly at various distances
but must be pursued as a fistula. Again, preparation and draping for • Membrane: hypopharynx
surgery is as above.