26.3 Neck Tumors, Radical Neck Dissection, Lymph Node Biopsy & Thyroid/Parathyroid Surgery

Why This Topic Matters on the NCE

Domain IV.A.6 covers the neck as four sub-topics: larynx and trachea, lymph node biopsies, parathyroid and thyroid, and neck tumors. This is a region where the airway, the great vessels, and the endocrine system are all within a few centimeters of the surgeon, and where a seemingly minor diagnostic procedure can be the safest possible anesthetic or the most dangerous one, depending entirely on what is in the mediastinum.

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1. Lymph Node Biopsy: The Anterior Mediastinal Mass Question

A scalene or supraclavicular lymph node biopsy is technically trivial. Its exam significance is entirely about why the node is being sampled.

When an anterior mediastinal mass is suspected — most commonly lymphoma in a young patient — a peripheral lymph node biopsy under local anesthesia is the safest diagnostic route and is specifically preferred to avoid general anesthesia altogether.

An anterior mediastinal mass is one of the few situations in which the induction of general anesthesia can cause immediate, irreversible cardiorespiratory collapse:

• Loss of spontaneous negative intrathoracic pressure, loss of chest wall and diaphragmatic tone, and supine positioning all allow the mass to compress the trachea, main bronchi, superior vena cava, pulmonary artery, or heart.
• Positive pressure ventilation does not reliably relieve the obstruction because the compression is often distal to the tube.

Preoperative assessment

• Symptoms that are positional — dyspnea, orthopnea, cough, syncope, or facial swelling that worsen when supine — are the most important red flags. Ask directly.
• Superior vena cava syndrome: facial and upper limb edema, distended neck veins, plethora.
• CT of the chest to quantify tracheobronchial cross-sectional narrowing.
• Echocardiography for cardiac and great vessel compression, ideally supine and upright.
• Flow-volume loops may show variable intrathoracic obstruction.

If general anesthesia is unavoidable

• Maintain spontaneous ventilation. Avoid neuromuscular blockade.
• Consider an awake or inhalational induction in a semi-sitting position.
• Have the patient in a position of comfort and be ready to turn them lateral or prone as a rescue maneuver, which relieves compression by letting the mass fall away.
• Have a rigid bronchoscope and a surgeon capable of using it immediately available to stent an obstructed airway.
• Femoral cardiopulmonary bypass standby, with groins prepped, for the highest-risk cases.
• Consider preoperative radiotherapy or steroids to shrink the mass, weighed against loss of tissue diagnosis.

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2. Thyroid and Parathyroid Surgery

Preoperative

• Ensure the patient is euthyroid. Operating on an untreated hyperthyroid patient risks thyroid storm, whose differential from malignant hyperthermia is a recurring exam item — thyroid storm has no muscle rigidity, no massive carbon dioxide production, and normal or mildly elevated creatine kinase.
• Assess for tracheal deviation, compression, and retrosternal extension with a CT scan. A large goiter can compress or deviate the trachea and cause superior vena cava syndrome.
• Tracheomalacia: a long-standing goiter can erode tracheal cartilage, so the airway may collapse after the supporting mass is removed. This is a postoperative extubation risk.

Intraoperative

• Recurrent laryngeal nerve monitoring with a nerve integrity monitor tube requires electrode contact with the vocal cords, so long-acting neuromuscular blockade must be avoided — use a short-acting agent for intubation or reverse promptly.
• Head-up positioning, careful eye protection, and arms tucked.
• Venous air embolism is possible with head elevation and open neck veins.

The postoperative emergencies

The delayed timing of hypocalcemia at 24 to 72 hours is the detail most often missed — it appears after the patient has left the recovery unit.

Parathyroidectomy

• Intraoperative parathyroid hormone monitoring: a fall of more than 50 percent from baseline 10 minutes after gland excision confirms adequate resection. The very short half-life of parathyroid hormone (3 to 5 minutes) makes this possible.
• Methylene blue was historically used to localize parathyroid tissue. It is a monoamine oxidase inhibitor and has caused serotonin syndrome in patients taking SSRIs and other serotonergic drugs; this use has largely been abandoned.
• Preoperative hypercalcemia causes dehydration, shortened QT, and altered mental status.

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3. Neck Tumors and Radical Neck Dissection

The airway is the whole problem

• Prior radiation to the neck is a major difficult-airway predictor. Radiated tissue is fibrosed, non-compliant, and immobile, and it defeats the external laryngeal manipulation and tissue displacement that laryngoscopy depends on. A previously easy airway can become impossible after radiotherapy.
• Tumor may directly obstruct or distort the airway; review the CT and any nasendoscopy findings.
• Plan an awake technique — flexible bronchoscopic intubation or awake tracheostomy under local anesthesia — when obstruction or radiation fibrosis is significant.

Intraoperative hazards

Free flap reconstruction

• Maintain normothermia, euvolemia, and adequate perfusion pressure — flap survival depends on it.
• Avoid vasoconstrictors where possible, since they compromise flap perfusion; treat hypotension with volume and depth adjustment first.
• Target a hematocrit around 30 percent, balancing oxygen carriage against viscosity.
• Avoid hypocapnia, which causes vasoconstriction.
• These are long cases: positioning injuries, pressure injuries, venous thromboembolism prophylaxis, and glucose control all matter.

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Exam Traps

• A supraclavicular node biopsy under local anesthesia is the right answer when an anterior mediastinal mass is suspected.
• Positional dyspnea is the red flag for a mediastinal mass. Ask about symptoms when supine.
• Post-thyroidectomy neck hematoma is opened at the bedside, not in the operating room.
• Hypocalcemia appears 24 to 72 hours after thyroidectomy, not immediately.
• A radiated neck is a difficult airway even if a previous intubation was easy.