Salivary Gland Surgery

🦷 Salivary Gland Surgery

Parotid anatomy, facial nerve branches, salivary tumours, Frey’s syndrome, submandibular gland excision and calculous disease — the essential MRCS salivary chapter.

Parotid Gland — Anatomy & Surgery

The parotid gland is the largest salivary gland, lying in the parotid space anterior to the ear between the ramus of the mandible and the mastoid process. It is unique in that the facial nerve (CN VII) passes through it, dividing the gland into superficial and deep lobes. This anatomical relationship is the key consideration in all parotid surgery.

Structures Passing Through the Parotid — Superficial to Deep

The Three-Layer Rule — “VRE” (Veins, Retromandibular, External carotid)

From superficial to deep within the parotid gland: Facial nerve (CN VII) — most superficial; then Retromandibular vein; then External carotid artery (deepest). The facial nerve is the most surgically important structure — it must be identified and preserved during parotidectomy.

Structure	Depth	Surgical Relevance
CN VII — Facial Nerve	Most superficial	Divides into temporofacial and cervicofacial trunks at the pes anserinus (goose’s foot) within the parotid. Separates superficial from deep lobe. Must be identified by nerve monitor and preserved.
Retromandibular Vein	Middle	Formed by superficial temporal + maxillary veins. Divides into anterior (joins facial vein) and posterior (joins posterior auricular → external jugular) tributaries. Can bleed significantly if injured.
External Carotid Artery	Deepest	Gives off posterior auricular and then divides into superficial temporal and maxillary arteries within/near the gland. Careful dissection required.
Parotid duct (Stensen’s duct)	Anterior surface	Exits anterior surface of gland, crosses masseter, pierces buccinator, opens into oral cavity opposite upper 2nd molar. At risk in facial lacerations over the masseter.
Auriculotemporal nerve	Accompanies superficial temporal vessels superiorly	Carries parasympathetic secretomotor fibres to parotid (via otic ganglion). Responsible for Frey’s syndrome after parotidectomy.

🧠 CN VII Terminal Branches — “Ten Zebras Brought My Cat”

Temporal — frontalis, upper orbicularis oculi, corrugator supercilii
Zygomatic — lower orbicularis oculi, zygomaticus major/minor
Buccal — buccinator, orbicularis oris, upper lip elevators
Marginal Mandibular — depressor anguli oris, depressor labii, mentalis. Most commonly injured in surgery. Often a single branch with no anastomosis.
Cervical — platysma

The temporofacial division = Temporal + Zygomatic + Buccal. The cervicofacial division = Buccal (sometimes) + Marginal Mandibular + Cervical.

Parotidectomy — Indications & Technique

Procedure	What is Removed	Indication	Key Point
Superficial parotidectomy	Superficial lobe (tissue lateral to CN VII)	Pleomorphic adenoma (most common indication), Warthin’s tumour, other benign superficial tumours	Most common parotid operation. Facial nerve identified and dissected from posterior to anterior. Marginal mandibular branch most at risk.
Total conservative parotidectomy	Both lobes, facial nerve preserved	Malignant tumours not involving nerve, recurrent pleomorphic adenoma, deep lobe tumours	Facial nerve preserved where oncologically safe. Higher morbidity than superficial.
Radical parotidectomy	Both lobes + facial nerve sacrificed	Malignant tumours with direct nerve invasion or encasement	Immediate facial nerve reconstruction (cable graft from greater auricular nerve or sural nerve) at same sitting.

Frey’s Syndrome

Frey’s Syndrome (Gustatory Sweating)

Frey’s syndrome is a late complication of parotidectomy occurring in up to 50% of patients, though symptomatic in ~10%. It manifests as flushing and sweating over the cheek/preauricular area during eating.

Mechanism — Aberrant Nerve Regeneration

The auriculotemporal nerve (V3) normally carries parasympathetic secretomotor fibres to the parotid gland (via the otic ganglion, supplied by CN IX via the lesser petrosal nerve). After parotidectomy, these parasympathetic fibres are severed. During healing, they grow aberrantly and reinnervate the sweat glands of the overlying skin (which are normally innervated by sympathetic cholinergic fibres). When the patient eats and parasympathetic stimulation occurs, instead of stimulating the (now absent) parotid gland, the signal activates sweat glands → gustatory sweating and flushing.

Feature	Details
Onset	Typically 6–18 months post-parotidectomy
Diagnosis	Minor’s starch-iodine test — iodine painted on cheek, dried; starch powder applied; patient eats → sweat turns starch-iodine blue/black in affected area
Prevention	Interposition of tissue between skin and parotid bed during surgery (SMAS flap, temporoparietal fascia, alloderm) reduces incidence
Treatment	Botulinum toxin A injection into affected area — blocks cholinergic transmission at sweat glands. Highly effective; repeat every 6–18 months. Antiperspirants (less effective). Repeat SMAS interposition surgery.

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