Thyroid Swellings in ENT Context

The thyroid is an ENT/head-and-neck examiner's favourite because the gland sits astride the airway and the nerves that move the vocal cords. For NEET PG, the high-yield angle is rarely thyroid endocrinology — it is the surgical anatomy of the recurrent and superior laryngeal nerves, airway compromise from goitre, retrosternal extension, midline neck swelling differentials, and the mandatory pre- and post-thyroidectomy laryngoscopy protocol. This note is built around those exam fixtures.

Surgical anatomy that the exam tests

The thyroid gland has two lobes joined by an isthmus that overlies the 2nd–4th tracheal rings. A pyramidal lobe (Lalouette's lobe) extends upward from the isthmus, usually on the left, a remnant of the thyroglossal tract. The gland is enclosed in the pretracheal fascia, and the suspensory ligament of Berry anchors it to the cricoid/first tracheal rings — clinically vital because the recurrent laryngeal nerve runs intimately close to Berry's ligament, the single most common site of nerve injury.

Structure	Course / relation	Why it matters in surgery
Recurrent laryngeal nerve (RLN)	In tracheo-oesophageal groove; close to ligament of Berry & inferior thyroid artery	Supplies ALL intrinsic laryngeal muscles except cricothyroid; injury → vocal cord palsy
External branch of superior laryngeal nerve (EBSLN)	Runs with superior thyroid artery near upper pole	Supplies cricothyroid; injury → loss of high-pitched voice, vocal fatigue
Inferior thyroid artery	Branch of thyrocervical trunk; crosses RLN	Ligate close to gland to protect RLN
Superior thyroid artery	First branch of external carotid	Ligate close to gland to protect EBSLN
Parathyroid glands	Posterior surface; blood supply mainly from inferior thyroid artery	At risk → post-op hypocalcaemia

High-yield: The recurrent laryngeal nerve supplies all intrinsic muscles of the larynx except the cricothyroid, which is supplied by the external branch of the superior laryngeal nerve. This single fact underlies most thyroid-surgery voice questions.

Recurrent laryngeal nerve — side-specific course

• Right RLN: loops under the right subclavian artery, then ascends in the tracheo-oesophageal groove. Because it hooks more laterally, the right RLN is more oblique and slightly more variable.
• Left RLN: loops under the arch of aorta at the ligamentum arteriosum, then ascends — runs more vertically and closer to the groove.
• A non-recurrent laryngeal nerve occurs almost exclusively on the right (~0.5–1%), associated with an aberrant right subclavian artery (arteria lusoria); it comes directly off the vagus and is a notorious cause of inadvertent injury.

High-yield: A non-recurrent laryngeal nerve is essentially always on the right side and is linked to an aberrant right subclavian artery. Left-sided non-recurrent nerve implies situs inversus.

Why the larynx position of the cord matters

To understand voice symptoms, you must remember the abductor vs adductor balance:

• The posterior cricoarytenoid (PCA) is the only abductor of the vocal cord (opens the airway). Mnemonic: "PCA = Please Come Apart" — opens the cords.
• All other intrinsic muscles (lateral cricoarytenoid, interarytenoid, thyroarytenoid) are adductors.
• The cricothyroid tenses/lengthens the cord, raising pitch.

Flow of cord position after nerve injury: RLN supplies abductor + adductors → on complete RLN palsy the abductor is lost more profoundly → cord settles in the paramedian position → unilateral RLN palsy gives a hoarse, breathy voice but usually no airway emergency; bilateral RLN palsy leaves both cords near the midline → stridor and airway obstruction (may need emergency tracheostomy).

High-yield: Bilateral abductor (RLN) paralysis → both cords paramedian → stridor + dyspnoea, voice may be near normal. Unilateral RLN palsy → hoarse breathy voice, airway adequate. This contrast is asked repeatedly.

Nerve injured	Voice change	Cord position / finding	Airway
Unilateral RLN	Hoarse, breathy, weak	Affected cord paramedian	Adequate
Bilateral RLN	Voice fair/near-normal	Both cords paramedian/midline	Stridor, may need tracheostomy
EBSLN (superior)	Loss of high pitch, vocal fatigue, monotone	Cord bowed, foreshortened; rotation of posterior commissure	Adequate
Combined RLN + SLN (complete)	Severe hoarseness, aspiration	Cord cadaveric (intermediate)	Aspiration risk

External superior laryngeal nerve — the "singer's nerve"

Injury to the EBSLN during ligation of the superior thyroid artery is classically under-recognised because the resting voice may sound normal. The patient — typically a teacher, singer, or public speaker — complains of early vocal fatigue, inability to reach high notes, and loss of voice projection (because cricothyroid normally tightens the cord for high pitch). On laryngoscopy: the affected cord is bowed, foreshortened, and the posterior commissure may rotate toward the paralysed side.

High-yield: EBSLN ("superior laryngeal nerve external branch") injury → voice fatigue and loss of high-pitched/falsetto voice with a near-normal conversational voice. Prevented by ligating the superior thyroid artery close to the upper pole/gland capsule, individually.

Goitre, tracheal effects and retrosternal extension

A large multinodular goitre can compress and displace the trachea. The classic radiological/clinical signs:

• Tracheal deviation: the trachea is pushed to the opposite side of an asymmetrically enlarging lobe. Assess with the Trail's sign / tracheal tug and confirm on imaging.
• Scabbard trachea: lateral compression narrows the trachea into a sheath-like shape (more typical of long-standing goitre).
• Tracheomalacia: chronic pressure softens tracheal cartilage → may collapse and cause post-operative airway obstruction after the supporting goitre is removed. A feared post-thyroidectomy complication.

Retrosternal (substernal) goitre

A goitre extending below the thoracic inlet into the superior mediastinum.

• Pemberton's sign: raising both arms above the head for ~1 minute → facial plethora/congestion, distended neck veins, stridor, or dizziness as the goitre is drawn into the thoracic inlet, compressing the great veins. A bedside marker of thoracic-inlet obstruction.
• Imaging of choice for retrosternal extent and tracheal compression: contrast CT of the neck and thorax (defines lower limit, tracheal narrowing, mediastinal extent, vascularity). Avoid iodinated contrast if the patient is hyperthyroid/awaiting radioiodine — use non-contrast CT or MRI in that situation.
• Most retrosternal goitres are removed via a cervical (collar) incision; sternotomy is reserved for primary mediastinal goitre, very large/recurrent lesions, or those with an intrathoracic blood supply.

High-yield: Pemberton's sign positive = retrosternal/thoracic-inlet obstruction. Investigation of choice for retrosternal extent and airway compression = CT neck + thorax.

Midline neck swelling — the ENT differential

This is where ENT examiners separate the candidates. The two classic midline swellings:

Feature	Thyroglossal cyst	Thyroid isthmus nodule
Position	Midline, usually below hyoid (subhyoid most common)	Over 2nd–4th tracheal rings (isthmus)
Moves with swallowing	Yes (attached to thyroid tract/hyoid)	Yes
Moves with tongue protrusion	Yes (tract attached to foramen caecum/hyoid)	No
Origin	Persistent thyroglossal duct remnant	Thyroid gland tissue
Surgery	Sistrunk operation (excise cyst + central hyoid body + tract to tongue base)	Hemithyroidectomy/isthmusectomy as indicated
Risk	Recurrence if hyoid not removed; rarely thyroglossal duct carcinoma (papillary)	Malignancy assessed by FNAC

High-yield: Moves on swallowing AND on tongue protrusion = thyroglossal cyst. Moves on swallowing only = thyroid/isthmus swelling. The tongue-protrusion test is the discriminator.

High-yield: Operation for a thyroglossal cyst = Sistrunk operation (must remove the central portion of the hyoid bone and the tract up to the foramen caecum to prevent recurrence).

Other midline/anterior neck masses to keep in the differential: a subhyoid bursa, dermoid cyst (does NOT move with tongue protrusion, doughy), ectopic/lingual thyroid (always image and check for normal gland before excising — it may be the only functioning thyroid tissue), and an enlarged Delphian (prelaryngeal) lymph node which may signal thyroid or laryngeal malignancy.

Clinical features of a thyroid swelling (ENT lens)

• Hoarseness / voice change in a patient with a thyroid mass is an ominous sign — it suggests RLN involvement by malignancy until proven otherwise.
• Stridor / dyspnoea / positional dyspnoea → tracheal compression.
• Dysphagia → oesophageal compression (rare; suggests large/posteriorly extending or malignant goitre).
• Horner's syndrome (ptosis, miosis, anhidrosis) → cervical sympathetic chain invasion by malignancy.
• Rapidly enlarging, hard, fixed swelling with cervical nodes → suspect anaplastic carcinoma or lymphoma in the elderly.
• A bruit over the gland → vascular Graves' goitre.

High-yield: New hoarseness in a thyroid swelling = recurrent laryngeal nerve palsy = malignancy until excluded. Always do laryngoscopy.

Diagnosis & investigation of choice

Approach (stepwise):

1. History + examination → swallowing test, tongue protrusion test, palpate for nodes, assess voice.
2. Indirect/flexible laryngoscopy → document vocal cord mobility (medico-legally essential before any thyroid surgery).
3. Ultrasound neck → first-line imaging; characterises nodule (solid/cystic), microcalcification, vascularity, and cervical nodes. USG is the investigation of choice for a thyroid nodule.
4. FNAC (fine-needle aspiration cytology) → the single most useful and cost-effective investigation to distinguish benign from malignant; results reported using the Bethesda system (categories I–VI).
5. Thyroid function tests (TSH ± T3/T4) → to assess functional status; a low TSH/"hot" nodule on scan is rarely malignant.
6. Radionuclide (Tc-99m / I-123) scan → only when TSH is low, to identify a hyperfunctioning ("hot") autonomous nodule.
7. CT/MRI neck-thorax → for retrosternal extension, tracheal compression, or suspected malignant invasion.

High-yield: FNAC is the investigation of choice for a solitary thyroid nodule to rule out malignancy; ultrasound is the imaging of choice. A follicular lesion (Bethesda III/IV) cannot be confirmed malignant on FNAC because the diagnosis of follicular carcinoma needs capsular/vascular invasion on histology — hence diagnostic hemithyroidectomy.

Bethesda system quick recall:

Bethesda	Category	Malignancy risk (approx)	Action
I	Non-diagnostic	—	Repeat FNAC
II	Benign	<3%	Follow-up
III	AUS/FLUS	~10–30%	Repeat FNAC / molecular
IV	Follicular neoplasm	~25–40%	Diagnostic hemithyroidectomy
V	Suspicious for malignancy	~50–75%	Surgery
VI	Malignant	~97–99%	Total thyroidectomy

Pre- and post-thyroidectomy laryngoscopy protocol

This is an ENT-specific exam fixture:

• Pre-operatively: every patient undergoing thyroid surgery must have vocal cord mobility documented by indirect/flexible laryngoscopy. A pre-existing palsy changes consent, surgical planning, and protects the surgeon medico-legally.
• Intra-operatively: intra-operative nerve monitoring (IONM) of the RLN and routine identification (not avoidance) of the nerve reduce injury. Capsular dissection and ligating the inferior thyroid artery close to the gland protect both the RLN and parathyroids.
• Post-operatively: repeat laryngoscopy to assess cord mobility, especially if there is a voice change, stridor, or weak cough.

High-yield: Laryngoscopy to check vocal cord mobility is mandatory both before and after thyroidectomy. Failure to document pre-op cord status is a classic exam "what is the error" stem.

Management / drug & procedure of choice

• Symptomatic obstructive goitre / suspicious or malignant nodule / cosmetic / retrosternal: surgery (hemithyroidectomy, total thyroidectomy as indicated).
• Toxic goitre pre-op: render euthyroid with carbimazole/methimazole; add beta-blocker (propranolol) for symptoms; Lugol's iodine (potassium iodide) for 10–14 days pre-operatively to reduce gland vascularity (Plummer's preparation).
• Differentiated thyroid carcinoma (papillary/follicular): total thyroidectomy ± neck dissection, followed by radioactive iodine (I-131) ablation and levothyroxine TSH-suppression.
• Post-thyroidectomy hypocalcaemia: IV calcium gluconate for acute tetany, oral calcium + active vitamin D (calcitriol) for maintenance.

High-yield: Lugol's iodine is given pre-operatively in toxic goitre to reduce gland vascularity and firm up the gland (Wolff–Chaikoff effect / Plummer's preparation) — do not give it long term.

Complications of thyroid surgery

• Haemorrhage / expanding neck haematoma: an airway emergency — release skin and strap-muscle sutures at the bedside immediately to decompress before returning to theatre.
• RLN injury: transient (neuropraxia) or permanent; unilateral → hoarseness, bilateral → stridor/airway obstruction needing tracheostomy.
• EBSLN injury: voice fatigue, loss of high pitch.
• Hypoparathyroidism / hypocalcaemia: perioral tingling, carpopedal spasm, Chvostek and Trousseau signs, prolonged QT.
• Thyroid storm: in inadequately prepared toxic patients.
• Tracheomalacia / tracheal collapse: post-removal of a long-standing large goitre.
• Wound infection, hypertrophic scar/keloid, chyle leak (low lateral dissection injuring thoracic duct on the left).

High-yield: Post-thyroidectomy stridor → think (1) bilateral RLN palsy, (2) expanding haematoma, (3) tracheomalacia, (4) hypocalcaemic laryngospasm. Haematoma is decompressed at the bedside immediately.

Key differentials

• Thyroglossal cyst vs thyroid isthmus nodule vs dermoid — see table above (tongue-protrusion test is key).
• Lateral neck swelling moving with swallowing: lateral thyroid lobe nodule vs branchial cyst (does not move with swallowing, anterior to sternomastoid upper third) vs carotid body tumour (pulsatile, mobile side-to-side not up-down, splaying of carotid bifurcation — "lyre sign").
• Hot vs cold nodule: a "cold" nodule on radionuclide scan has higher malignant potential; a "hot" (autonomous) nodule is almost always benign.
• Hashimoto thyroiditis vs malignancy: diffuse firm gland, raised anti-TPO antibodies; can rarely harbour lymphoma.

Recently asked / exam angle

• "Muscle NOT supplied by the recurrent laryngeal nerve" → cricothyroid (answer).
• "Only abductor of vocal cord" → posterior cricoarytenoid.
• "Voice fatigue / loss of high pitch after thyroidectomy — nerve injured?" → external branch of superior laryngeal nerve.
• "Swelling moving with deglutition AND tongue protrusion" → thyroglossal cyst; operation = Sistrunk.
• "Non-recurrent laryngeal nerve — which side & association?" → right side, aberrant right subclavian artery.
• "Bilateral abductor palsy presentation" → stridor with preserved voice.
• "Sign elicited by raising arms in retrosternal goitre" → Pemberton's sign.
• "Investigation of choice for solitary thyroid nodule" → FNAC; "imaging of choice" → ultrasound; "retrosternal extent" → CT neck-thorax.
• "Immediate management of post-thyroidectomy airway obstruction with neck swelling" → open the wound at bedside (release haematoma).
• "Why give Lugol's iodine pre-op?" → reduce vascularity of gland.

Rapid revision

1. RLN supplies all intrinsic laryngeal muscles except cricothyroid (EBSLN).
2. Posterior cricoarytenoid = only abductor → opens cords.
3. Unilateral RLN palsy = hoarse breathy voice; bilateral RLN palsy = stridor (cords paramedian).
4. EBSLN injury = voice fatigue + loss of high pitch (the "singer's nerve").
5. Non-recurrent laryngeal nerve = right side, aberrant right subclavian artery.
6. RLN is most at risk at the ligament of Berry and near the inferior thyroid artery.
7. Thyroglossal cyst moves with swallowing AND tongue protrusion → treat by Sistrunk operation.
8. Pemberton's sign = retrosternal goitre/thoracic-inlet obstruction; image with CT neck-thorax.
9. FNAC = investigation of choice for a thyroid nodule; USG = imaging of choice; reported by Bethesda.
10. Lugol's iodine pre-op reduces gland vascularity (Plummer's preparation).
11. Vocal cord laryngoscopy is mandatory before AND after thyroidectomy.
12. Post-thyroidectomy stridor → bilateral RLN palsy, haematoma (decompress at bedside), tracheomalacia, or hypocalcaemia.