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22 Cards in this Set
- Front
- Back
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Main surgical consideration to avoid in thyroid surgery
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Carotid sheaths on either side (vagus n., carotid a, IJV)
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Embryology of Thyroid and Variants
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Normally starts off at the base of tongue, as fetus elongates it descends to neck and assumes position. Parathyroids come from pharyngeal pouch
Variants a) Lingual Thyroid - remnants on back of tongue that did not descend. Tissue functional and only problematic when enlargement occurs and can lead to airway obstruction or trouble swallowing b) Thyroglossal duct cyst - band of tissue in duct that connects foramen cecum on back of tongue to thyroid, can become cystic, get infected, etc. leading to dysphagia |
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Primary Thyroid Diseases Seen
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Nodular Thyroid Disease - very common (80% people), females more, solitary to multiple, become cystic when outgrow blood supply so they degenerate, Only 5-10% malignant
Goiter - Thyroid enlargement, can lead to dysphagia and dyspnea, Substernal extension into chest Inflammatory disease - Hashimoto's, Riedel's struma, Graves' Disease Functional Disorders - Hypothyroidism and Hyperthyroidism Thyroid Malignancy - 5-10% of nodules, more female |
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Types of Inflammatory Thyroid Disease
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Hashimoto's - large inflammatory infiltrate
Riedel's struma - scar tissue replaces thyroid Graves' Disease - dense, woody, rubbery thyroid from mild infiltrate |
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Treatment differences Hypothyroidism vs Hyperthyroidism
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Hypothyroidism - medically manage with hormones
Hyperthyroidism - Can get toxic goiter, graves' ophthalmopathy, treat with beta blockers, methimazole, PTU and radioablation with I-131. Surgery more definitive so may be perfered |
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Thyroid Malignancy Types, Signs/Sx, US characteristics, FNA, RF for poor prognosis
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Types: Papillary (most common), follicular (least), medullary (familial and sporadic), Anaplastic (MOST AGGRESSIVE human malignancy, cannot get margins, dismal prognosis)
Signs and Symptoms: in advanced disease, Firm hard nodule, enlarged lymph nodes in neck, pain around trachea or esophagus, hoarseness due to impingement on recurrent laryngeal nerve US Characteristics: Hypervascularity, irregular borders with infiltration, microcalcifications FNA biopsy: 22 gauge needle and analyze cytologically. Use US guidance RF for poor prognosis Age > 40 (automatically Stage IV), Size > 2cm (If don't have either of last two then 90% survival 5 year). Extracapsular extension - incidence of regional involvement and nodal metastases can lead to "regional failuer", metastasis |
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Gene implicated in familial medullary thyroid malignancy
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MEN 2 Syndrome
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2 Surgical Approaches to Thyroid
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1) Conventional Thyroidectomy - Large incision 6-7cm long, used for large nodules and goiter. Used to be used to prevent tetany by older thyroidectomys that removed Ca++ too (loss of parathyroids means severe Ca drop in serum).
Creates elevated skin flaps, ligate sup thyroid artery with ACE23P, uses suction drains Also used in Graves' due to inflammatory nature, 2) Minimally Invasive Thyroidectomy (MIT) - enables visualization of PT glands and recurrent layngeal nerve. Can remove gland with small incision and endoscopy 3cm incision, endoscopes, no tsuction drains, mostly outpatient Indicated: normal size pt (not obsese), normal to slightly enlarged gland (3-5cm), small malignancies and central compartment dissection Closed with harmonic shear that vibrates at 10,000 Hz and generates mechanical heat to coagulate |
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Contraindications for MIT
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Large, Thick Necks
Large glands/lesions Hashimoto's Tyroiditis & Graves' Disease - usually not MIT but can be |
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Advantages of MIT
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Excellent cosmesis, minimal pain and discomfort, outpatient, no drains
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Advantages of Harmonic ACE
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Access, reduced instrument exchanges, cuts and coags simultaneously, no electricity, safer dissection near vital structures
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Hyperparathyroids Anatomy and Embryology and Location
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4 PT glands on backside of the thyroid
Embryology - derived from 3rd and 4th pharyngeal pouches, associated with thymus, anterior-posterior relationship of the gland and recurrent laryngeal nerve used as a landmark to determine if it is superior or inferior gland Location SPT - from 4th pharyngeal pouch - posterior and superior to RLN IPT - from thymic horn - anterior to RLN |
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Calcium set point theory
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Parathyroids (PTH) and Thyroids (calcitonin) maintain balance with calcitonin stimulating bone resorption and PTH stimulating bone breakdown
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Hyperparathyroidism Epidemiology, Symptoms, Workup
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Fairly common, Female more, can be symptomatic or asymptomatic
Symptoms: (in symptomatic hypercalcemia) a) Nephrolithiasis (kidney stones) b) Musculoskeletal aches and pains - osteoporosis, fractures, sore joints, aches and pains c) Abdominal complaints - particularly constipation d) Vague Neuromuscular syndrome - fatigue and lethargy, memory issues, low energy Mnemonic - stones, bones and groans and psychological overtones Workup - Total serum Ca++, albumin, ionized serum calcium, PTH, Vitamin D levels, 24 hr urinary Ca++ |
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MEN I syndrome
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Hyperparathyroidism, pituitary adenomas, abdominal tumors like gastrinoma
MEN II can have HPT but more medullary thyroid cancer |
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Surgery in Asymptomatic Patients, who gets
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Age <50 years, Ca > 1.0mg/dL above upper normal
24 hr urinary calcium excretion > 400 mg/day Creatinine clearance reduced >30% Bone mineral density T score < -2.5 SD (osteoporosis) Non-compliant patients |
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Primary HPT causes
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Means disease is intrinsic to parathyroid gland not secondary to another condition like CKD.
80% solitary adenoma 15% multi-gland hyperplasia 5% "double" adenoma |
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4 Types of Pre-Operative Localization for HPT
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1) Sesta-MIBI (Cardiolite) scan - originally used for heart but since PT glands take up cardiolite too. 85% sensitive for solitary disease but less than 50% for multi-gland disease.
Use 99Tc isotope and SPECT CT, after 2-4 hours only PTH should retain isotope 2) Non-localizing sesta-MIBI scan, more likely for multi-gland disease and smaller glands. Likelihood of scans localizing is based mainly on higher gland weight, not correlated with vascularity 3) Fusion of Sesta-MIBI with SPECT/CT - useful to find ectopic glands - can also use CTA with I-123 imaging 4) Ultrasound - High resolution with color Doppler has 75% sensitivity, complimentary to sesta-MIBI. enables assessment of CONCOMITANT THYROID PATHOLOGY. Also can see vascularity |
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Associations with HPT
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Solid tumor malignancy - often in thyroids, may be picked up with US, and due to Vit D metabolism
Coronary artery disease - due to Ca role |
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Surgical Approaches to HPT, Adjuncts
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Shift from large incisions and 4 gland explorations to preoperative localization and minimally invasive resection
a) BIL 4 gland exploration (only used if Sesta-MIBI nor US show the PT glands b) Unilateral Neck Exploration c) Minimally Invasive Parathyroidectomy (endoscopic) d) Radio-guided minimally invasive parathyroidectomy (radio isotype localization in OR) Adjuncts - a) Gamma probe - used after Sesta-MIBI to detect radiation levels and hotspot of PT, only used in revisions and ectopic b/c localization better b) Rapid intra-operative PTH assay - PTH half life is only 3 minutes, so remove gland, wait 10 minutes and look for 50% reduction in PTH to show 97% success rate c) Methylene Blue d) 5-aminolevulinic acid (5-ALA) - only don in mice but light up the PT glands |
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When is BIL neck exploration surgery indicated in PTH
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Men I syndrome (4 gland hyperplasia)
Secondary or Tertiary hyperparathyroidism Recurrent disease Ectopic glands Non-localizing studies |
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How to find missing glands
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Look:
Posterior to the RLN Between esophagus and CCA Retro-pharyngeal and -esophageal dissection Thymic dissection down to inominate artery Explore carotid sheath contents Ipsilateral thyroid lobectomy |
