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Thyroid disease spectrum

1. Arteries:
   • superior thyroid (external carotid)
   • inferior thyroid (thyrocervical trunk of subclavian)
   • Accessory thyroid ima
2. Veins:
   • Superior
   • Middle
   • Inferior
3. Nerves:
   • Recurrent laryngeal (cricoarytenoids - supply vocal cords)
   • Superior laryngeal

[Thyroid hormone physiology & disease spectrum]

Thyroid Neoplasms

1. Papillary 70% - younger population, good prognosis, TSH-dependent
2. Follicular 20%
3. Anaplastic 5% - older population
4. Medullary 5% - from parafollicular C-cells
5. Lymphoma - rare 

Management of thyroid disease

1. History
   • Thyroid symptoms
   • Medications
   • Previous radiation exposure
   • Familial history
2. Examination
   • Neck
   • General examination: signs of thyroid disease - hands, eyes, cardiovascular system
3. Investigations
   • TSH, T4, thyroid autoantibody screen
   • USS: sensitive for detecting thyroid nodules, used to guide FNA
   • FNAC: Most reliable test for thyroid nodules
   • Radio-isotope scans no longer routinely used ("hot" nodules were benign and "cold" nodules were not)

Hemithyroidectomy procedure

1. GA + Supine + head-up tilt of 15'
2. Head rests on ring, sandbag in interscapular position
3. Dissect down to thyroid
   • Transverse collar incision approximately 2finger breadths above suprasternal notch
   • Divide skin and platysma
   • Extend superior flap to thyroid, inferior flap to suprasternal notch
   • Expose strap muscles
   • Divide cervical fascia in midline and retract strap muscles laterally
4. Dead with surrounding structures
   • Ligate and divide middle and inferior thyroid veins
   • Inferior thyroid artery identified and ligated in continuity as inferiorly as possible
   • Identify recurrent laryngeal nerve in its groove between trachea and oesophagus (and protect)
   • Identify parathyroid glands and preserve
5. Remove thyroid
   • Superior vascular pedicle is ligated and divided
   • thyroid lobe mobilised and excised
   • oversew isthmus with absorbable sutures
6. Close
   • Haemostasis completed
   • Suction drain placed in subfascial space
   • Fascia closed in midline with absorbable sutures
   • Skin + platysma closed
   • Skin closed with non-absorbable subcuticular suture

Complications

1. Haematoma - may cause respiratory embarassment
2. Recurrent laryngeal nerve palsy 1%
   • Single nerve paresis results in hoarse voice
   • Both nerves leads to paralysis
3. Superior laryngeal nerve palsy
4. Hypothyroidism
5. Hypoparathyroidism - causes hypocalcaemia - check calcium level post-operatively
6. Scarring

Post-op: radio-iodine scan can demonstrate remnants of thyroid tissue or distant metastases
Remaining tissue can be ablated
Serial thyroglobulin measurement 6-12 month intervals (acts as marker for tumour recurrence)