Clinical Case - Larynx and Neck
A 30 year old substitute teacher consults her physician, complaining of a swollen neck. She had first noticed the swelling 3 months ago. Over the last three months, it had been increasing in size. She also had some breathlessness. On examination, a solitary swelling of firm consistency was found on the right side of the larynx and trachea. The small mass was not attached to the skin and there were no changes to the overlying skin. The swelling moved upward with swallowing. Further tests showed that the mass was a carcinoma of the thyroid gland. The mass was surgically removed.

Questions to consider:
  1. What is the gross form and location of the thyroid gland?
    The thyroid has left and right lobes connected by an isthmus. It extends from the thyroid cartilage to about the fourth or fifth tracheal ring. The isthmus lies anterior to the second, third and fourth tracheal rings. A pyramidal lobe may or may not be present, extending superiorly from the region of the isthmus.
  2. Why did the tumor move upward when the patient swallowed?
    The thyroid gland is invested in a sheath derived from the pretracheal fascia. This holds the gland onto the larynx and the trachea, so the thyroid follows the movements of the larynx during swallowing. Any pathological swelling of the thyroid will move upwards with swallowing, distinguishing it from a mass in some other part of the neck.
  3. How did the tumor cause breathlessness?
    Since the thyroid is anterior to the trachea, an abnormal mass can push on the trachea and partially occlude the lumen, causing breathlessness.
  4. Which lymph nodes should the physician examine for metastases if a malignant tumor is suspected?
    The thyroid gland is drained primarily by the deep cervical lymph nodes.
  5. What structures can be damaged during thyroidectomy if the surgeon is not careful?
    The two main arteries supplying the gland are accompanied by nerves that can be damaged during thyroidectomy. The superior thyroid artery is related to the external laryngeal nerve. This nerve supplies the cricothyroid and cricopharyngeus muscles. The inferior thyroid arteries are related to the recurrent laryngeal nerve.
  6. Post-operatively, the surgeon carefully ensured that the patient was speaking properly. Why?
    Damage to the external laryngeal nerve can result in the inability to tense the vocal folds, producing weakness of the voice; the cricothyroid muscle is unable to contract. Bilateral damage to the recurrent laryngeal nerves may cause the patient to lose speech completely and cause difficulty in breathing.
A 32-year-old woman, who has been diagnosed with having toxic multinodular goiter for two years, is complaining of increasing shortness of breath and dysphagia that gets worse when lying in bed. Her usual complaint of intolerance to hot atmosphere, sweating, weight loss and emotional irritability has worsened lately. The surgeon assesses her condition and decides that surgery is indicated. He suggests doing bilateral subtotal thyroidectomy to relieve symptoms particularly of the lower parts of the gland. The patient was put on a two-week course of iodine and antithyroid drugs before the operation to reduce the vascularity of the thyroid.

Questions:
  1. Why would patients with goiter be likely to have shortness of breath and dysphagia?
    The enlarged thyroid will press initially on the trachea. Pressure will increase when it reaches a large size since the sternothyroid muscle will be forced down to the superior mediastinum, and the trachea and esophagus will be compressed.

  2. Which vessels should be ligated before doing lower subtotal thyroidectomy?
    The inferior thyroid artery, a branch of the thyrocervical trunk, runs posterior to the carotid sheath to reach the posterior aspect of the gland. It divides into several branches, which pierce the pretracheal fascia to supply the inferior pole of the gland. Other vessels to be dealt with are the middle and inferior thyroid veins.
  3. Which structure should be carefully protected from injury during such an operation?
    The recurrent laryngeal nerve, because of its intimate relation to the inferior thyroid artery, is susceptible for injury during thyroidectomy.
  4. What are the most likely complications that may arise from such an operation?
    Bleeding is possible due to the rich blood supply to the thyroid. Injury to the recurrent laryngeal nerve may result in temporary hoarseness of the voice, permanent loss of voice, or even death due to laryngeal spasm. Another possible complication of thyroidectomy is the inadvertent removal of the parathyroid glands, which may cause a severe convulsive disorder known as tetany.
A 65-year-old man presented in his physician's office complaining of frequent headaches focused primarily on the right side and a series of four episodes of transient dysfunction involving the left side of his body during the last two months. These episodes involved progressive symptoms, beginning with only numbness in his left hand during the first episode, muscle weakness in his left arm and left leg during the second and third episodes, and limb weakness accompanied by slurred speech during the fourth episode. Auscultation of the neck indicated a bruit present on the right side. An arteriogram revealed ulcerated stenosis of the right carotid bifurcation and mild left-sided carotid stenosis. The patient was advised that he should undergo a carotid endarterectomy immediately in order to prevent an otherwise imminent stroke. The patient submitted to the surgery, which was performed without incident, and has experienced no further headaches or episodes of left-sided dysfunction.

Questions to consider:
  1. What are bruits and what causes them in the neck?
    In this context, a bruit is a systolic murmur heard only in the neck. It is caused by turbulent and noisy blood flow over a roughened surface (i.e. an atherosclerotic plaque).
  2. What is an arteriogram and how is it obtained?
    An arteriogram is a radiograph demonstrating the course and lumen diameter of an artery and its tree. Arteriograms are obtained via x-ray imaging after a injection of a radiopaque contrast medium into the arterial tree.
  3. What is an endarterectomy?
    An endarterectomy is a surgical procedure for removing an occlusion from an artery. This type of surgery is often used to remove threatening atherosclerotic lesions from arteries such as the carotid and coronary arteries. The procedure involves excision of the intima and plaque and part of the media of the artery in order to leave a smooth surface.
  4. What structures are particularly vulnerable to damage due to their presence in or near the carotid sheath when an endarterectomy is performed?
    The vagus nerve and its branches (the superior laryngeal and an aberrant recurrent laryngeal), the hypoglossal nerve, the mandibular branch of the facial nerve, the ansa cervicalis, the accessory nerve, and the internal jugular vein are all vulnerable to damage during an endarterectomy. In addition, some arteries and veins are routinely divided during this surgery (including the facial vein, sternocleidomastoid artery and vein, and the superior thyroid artery). Injuries to the glossopharyngeal nerve, branches of the cervical plexus (transverse cervical and great auricular), the brachial plexus (due to stretching), the phrenic nerve, and the cervical sympathetic plexus have also been reported in the literature. The moral to this story is that the anatomy of this region is extremely complex and great care must be exercised in performing this sort of procedure.
  5. Why were the patient's symptoms generally transient and not permanent?
    The transience of the patient's symptoms could be linked to a number of things, including arterial spasm, transient thrombosis, and the like. All of these things will likely have an amplified effect if the carotid artery is already severely stenotic. The effects of the ischemia of the brain are not permanent because many of the instigators (i.e. arterial spasm) are reversible, and because, as long as the lesion is at the level of the carotid bifurcation and is unilateral, collateral circulation in the brain provided by the circle of Willis, if adequate, will keep the ischemic region at least partially perfused.
  6. Where do atherosclerotic lesions usually form in the carotid arteries?
    The most common location for atherosclerotic plaque formation is at the bifurcation or branch points of arteries, in the case of the carotid arteries it is at the carotid bifurcation.

References:

After observing the procedure many times and numerous attempts on cadavers, you are called on to perform a subclavian catheterization on a critically ill adult patient in order to monitor her central venous pressure. An infraclavicular approach on the right side is chosen.

Questions to consider:
  1. Where is the subclavian vein located?
    The subclavian vein is found in the lower part of the omoclavicular or subclavian triangle. It is the continuation of the axillary vein, beginning at the lower border of the first rib. It crosses the clavicle just medial to the midclavicular point and proceeds superiorly and arches over the first rib anterior to the anterior scalene muscle before turning posteriorly again and descending into the thorax.
  2. What surface anatomical landmarks are critical for guiding infraclavicular subclavian catheterization?
    The midclavicular point and the lower border of the clavicle are critical for locating the subclavian vein for venipuncture. In addition, the suprasternal notch is used to aim the needle once it is inserted under the clavicle.
  3. Describe the relationships of the subclavian vein with other neurovascular structures in the vicinity.
    The subclavian vein is the most anterior neurovascular structure in the subclavian triangle. Posterior to it at the first rib is the anterior scalene muscle, which separates the vein from the subclavian artery and the inferior trunk of the brachial plexus. Just medial to the first rib, the subclavian vein is joined by the internal jugular vein before proceeding into the thorax to join with the brachiocephalic vein from the other side to form the superior vena cava. On the left side, the thoracic duct empties into the left subclavian vein at its junction with the internal jugular.
  4. Why might a right-sided approach be preferred to a left-sided one for subclavian catheterization?
    A right-sided approach is preferred because laceration of the thoracic duct, which empties into the left subclavian vein, can be avoided by catheterization on the right side.
  5. Based on your knowledge of anatomy, identify several potential complications associated with subclavian catheterization.
    Potential complications to subclavian catheterization include pneumothorax, hemothorax, cardiac tamponade, bacterial infection or sepsis, and brachial plexus injuries.
You have been asked to assess the post-operative condition of a 65 year old man who has been surgically treated for carcinoma of the tongue. Since the tumor was in its early stages, the surgeon has performed a left-sided hemiglossectomy with block dissection of the left neck. In this operation all posterior triangle lymph nodes were removed, along with other structures. The patient was recovering well and was able to move.

Questions to consider:
  1. Which important nerve is likely to be injured in posterior neck triangle operations? How would you test for its integrity post-operatively?
    The accessory nerve (XI) is likely to be injured in such an operation. Its injury in the posterior triangle will cause paralysis of the trapezius muscle. The usual clinical test for assessing the integrity of the nerve is by asking the patient to shrug his/her shoulder.
  2. What other structures are important to consider in such operations?
    Upper and middle trunks of the brachial plexus; third part of the subclavian artery and suprascapular nerve and artery, and branches of the cervical plexus.
  3. What groups of lymph nodes might the surgeon remove from the posterior triangle?
    Supraclavicular lymph nodes are relatively important, (they are part of the deep cervical lymph nodes); other less important nodes are the occipital situated at the apex of the triangle.

References:

A medical student was celebrating the end of midterm exams with her friends in a seafood restaurant when she started feeling a prickling sensation in her neck after swallowing a large bite of smoked fish. The pain was getting worse, and attempts to clear it with drinks failed. At the emergency room a plain X-ray of her neck showed a tiny fish bone lodged in the lower part of the pharynx. The bone was quickly removed under general anesthesia, and the patient was discharged a few hours later.

Questions to consider:
  1. Which are the most usual places for swallowed foreign bodies to be lodged?
    The piriform recess and the valleculae on either side of the median glosso-epiglottic fold.
  2. What is the piriform recess?
    This is a small, pear-shaped depression of the laryngopharyngeal cavity on each side of the inlet of the larynx. It is separated from the inlet by the aryepiglottic fold. Laterally the piriform recess is bounded by the medial surfaces of the thyroid cartilage and the thyrohyoid membrane. The branches of the internal laryngeal and inferior laryngeal nerves (continuation of recurrent laryngeal) lie deep to the mucous membrane of the piriform recess.
  3. Fish bones and other foreign bodies may pierce the mucous membrane of the recess and cause injury to the internal laryngeal nerve. What are the possible consequences of this injury?
    Injury to the internal laryngeal nerve will result in anesthesia of the laryngeal mucous membrane as far inferiorly as the vocal folds.