• The term goiter refers to:
    • An abnormal growth of the thyroid gland
  • Depending on the etiology goiters can be:
    • Diffuse
    • Nodular
  • May be associated with:
    • Normal thyroid hormone production
    • Decreased thyroid hormone production
    • Increased thyroid hormone production
  • The clinical manifestations vary with:
    • Thyroid function and with the size and location of the goiter
  • Anatomical Relationships:
    • In healthy adults without iodine deficiency:
      • A normal thyroid gland is approximately:
        • 4.0 cm to 4.8 cm x 1.0 cm to 1.8 cm x 0.8 cm to 1.6 cm in size
      • Mean sonographic volume of:
        • 7 mL to 10 mL:
          • Thyroid volume measured by ultrasonography:
            • Is slightly greater in men than women
            • Increases with age and body weight
            • Decreases with increasing iodine intake
  • Weight of the thyroid gland:
    • 10 grams to 20 grams:
      • As high as 30 grams is considered normal
  • The normal thyroid gland:
    • Is immediately caudal to the larynx and encircles the anterolateral portion of the trachea
  • The thyroid gland is bordered by:
    • The trachea and esophagus posteriorly
    • The carotid sheath laterally
  • Enlarging thyroid lobes:
    • Usually grow outward:
      • Because of their location in the anterior neck in front of the trachea:
        • Covered only by the thin strap muscles, subcutaneous tissue, and skin
    • As a result of this outward growth:
      • Even very large goiters:
        • May not compress the trachea or impinge on the great vessels lateral to the lobes:
          • However, in patients with substantial enlargement of one lobe or asymmetric enlargement of both lobes:
            • The trachea, esophagus, or blood vessels:
              • May be displaced or, less often, compressed
          • Bilateral lobar enlargement:
            • Especially if the goiter extends posterior to the trachea:
              • May cause either:
                • Compression or concentric narrowing of the trachea
                • Compression of the esophagus
                • Compression of the jugular veins
  • The thoracic inlet:
    • Is an ovoid area that measures approximately 5 cm x 10 cm:
      • Boundaries:
        • The sternum anteriorly
        • The first thoracic vertebral body posteriorly
        • The first ribs laterally
    • The inlet is traversed by the:
      • Trachea
      • Esophagus
      • Blood vessels
      • Nerves
    • The inferior pole of each thyroid lobe:
      • Normally lies above the thoracic inlet:
        • However, with some goiters, there is growth of one or both lobes through the inlet into the thoracic cavity:
          • Which can result in obstruction of any of the structures in the inlet:
            • Such goiters are called substernal:
              • Although retrosternal is probably a more precise term
  • Most substernal goiters are in the:
    • Anterolateral mediastinum:
      • But approximately 10%:
        • Are located primarily in the posterior mediastinum
  • The prevalence of substernal goiter as a percentage of thyroidectomies:
    • Ranges from 2% to 19%

#Arrangoiz #ThyroidSurgeon #HeadandNeckSurgeon #CancerSurgeon #MSMC #MountSinaiMedicalCenter #Miami #Mexico #Goiter #SubsternalGoiter

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