PART 1 - Classification of Cervical Lymph Nodes (AAO-HNS/Memorial Sloan Kettering Level System)

Source: Cummings Otolaryngology Head and Neck Surgery; Scott-Brown's Otorhinolaryngology Head & Neck Surgery; Fischer's Mastery of Surgery 8e

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LEVEL I - Submental and Submandibular Group

Level Ia - Submental Triangle

Level Ib - Submandibular Triangle

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LEVEL II - Upper Jugular Group

Level IIa - Anterior to SAN

Level IIb - Posterior to SAN ("Submuscular Recess")

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LEVEL III - Middle Jugular Group

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LEVEL IV - Lower Jugular Group

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LEVEL V - Posterior Triangle Group

Level Va - Upper Posterior Triangle (Spinal Accessory nodes)

Level Vb - Lower Posterior Triangle (Transverse cervical and supraclavicular nodes)

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LEVEL VI - Anterior Compartment Group (Central Compartment)

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LEVEL VII - Superior Mediastinal Group (added by some systems)

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Quick Reference Summary Table

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PART 2 - Neck Dissection: Types and Classification

Source: Cummings Otolaryngology Head and Neck Surgery; Sabiston Textbook of Surgery; Scott-Brown's Otorhinolaryngology

NECK DISSECTION
├── 1. Radical Neck Dissection (RND)
├── 2. Modified Radical Neck Dissection (MRND) - Types I, II, III
├── 3. Selective Neck Dissection (SND)
│   ├── a. Supraomohyoid (I-III)
│   ├── b. Lateral (II-IV)
│   ├── c. Posterolateral (II-V)
│   └── d. Central/Anterior (VI)
└── 4. Extended Neck Dissection

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1. Radical Neck Dissection (RND) - "Classical"

• Spinal accessory nerve (SAN/CN XI)
• Internal jugular vein (IJV)
• Sternocleidomastoid muscle (SCM)

• Superior: Inferior border of mandible
• Inferior: Clavicle
• Medial: Lateral border of strap muscles
• Lateral: Anterior border of trapezius

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2. Modified Radical Neck Dissection (MRND) - Types I, II, III

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3. Selective Neck Dissection (SND)

3a. Supraomohyoid Neck Dissection (SOHND)

• Levels removed: I, II, III
• Used for: Oral cavity cancers (floor of mouth, tongue, buccal mucosa)
• Rationale: Oral cavity primaries drain predictably to Levels I-III

3b. Lateral Neck Dissection

• Levels removed: II, III, IV
• Used for: Laryngeal cancer, oropharyngeal cancer, hypopharyngeal cancer
• Rationale: These sites drain to the jugular chain (Levels II-IV)

3c. Posterolateral Neck Dissection

• Levels removed: II, III, IV, V + suboccipital + retroauricular nodes
• Used for: Cutaneous malignancies of posterior scalp/neck, soft tissue sarcomas
• Rationale: Posterior scalp drains to posterior triangle + jugular chain

3d. Central (Anterior) Neck Dissection

• Level removed: VI (anterior compartment only)
• Used for: Thyroid cancer, laryngeal cancer (subglottic), pyriform sinus carcinoma, tracheal tumors
• Rationale: Level VI is the primary echelon for central neck/thyroid drainage

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4. Extended Neck Dissection

• Adding Level VII (superior mediastinal nodes)
• Removing the carotid artery (if encased)
• Removing the hypoglossal nerve (CN XII) if invaded
• Removing the vagus nerve or skin

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Selective Neck Dissection by Primary Site - Quick Reference

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The Scott-Brown Classification Table (Simplified)

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PART 3 - Complications of Neck Dissection

Source: Cummings Otolaryngology, Chapter 118 (pp. 2296-2381)

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A. Intraoperative Complications

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B. Postoperative Complications

1. Chylous Fistula (Chyle Leak)

• Incidence: ~1-2% of neck dissections involving Level IV
• Cause: Injury to thoracic duct (left side, near Level IV) or right lymphatic duct
• Signs: Milky fluid in drain, especially after resuming oral feeds
• Management:
  • Output < 600 mL/day: Conservative - low-fat diet or TPN, pressure dressings, closed suction drain
  • Output > 600 mL/day: Surgical re-exploration and ligation
• Prevention: After Level IV dissection, increase intrathoracic pressure (anesthesiologist) for 20-30 sec to visualize leaks; clip or ligate with 5-0 silk

2. Bleeding / Hematoma

• Usually occurs immediately after surgery
• Ballooning/swelling of skin flaps = hematoma
• Management: Return to OR under sterile conditions; bedside drainage is inadequate and increases infection risk

3. Air Leaks

• Common day after surgery via improperly secured drain
• More serious if there is communication with tracheostomy or mucosal suture line (contaminated secretions enter)

4. Facial and Cerebral Edema

• Occurs after bilateral RND where both IJVs are ligated
• Bilateral IJV ligation → increased intracranial pressure, cerebral venous hypertension, SIADH → dilutional hyponatremia → worsens cerebral edema
• Prevention: Preserve at least one external jugular vein in bilateral RND; limit perioperative fluid administration

5. Spinal Accessory Nerve (SAN / CN XI) Injury

• Most significant functional morbidity of RND
• Results in: Shoulder drop, winging of scapula, pain, limited abduction of arm above shoulder
• "Shoulder syndrome" = most disabling complication
• Preserved in MRND and SND

6. Hypoglossal Nerve (CN XII) Injury

• Results in: Ipsilateral tongue deviation, dysarthria, dysphagia
• At risk during Level Ib/submandibular triangle dissection (lies in deep portion of submandibular triangle)

7. Marginal Mandibular Branch of Facial Nerve (CN VII) Injury

• Results in: Lower lip droop on ipsilateral side
• At risk when raising the superior flap over the mandible
• Must identify and protect during Level I dissection

8. Phrenic Nerve Injury

• Results in: Ipsilateral hemidiaphragm paralysis
• Lies on anterior surface of anterior scalene muscle (deep to Level IV/V dissection)

9. Brachial Plexus Injury

• Rare; occurs with deep dissection in posterior triangle (Level V)
• Results in: Upper limb weakness/paresthesias

10. Vagus Nerve (CN X) Injury

• Lies within the carotid sheath (medial to IJV)
• Injury → hoarseness (recurrent laryngeal nerve), cardiac dysrhythmia

11. Sympathetic Chain Injury

• Results in: Horner's syndrome (ptosis, miosis, anhidrosis, enophthalmos)
• Lies posterior to carotid sheath

12. Wound Infection / Wound Breakdown

• Higher risk after prior radiotherapy
• Pharyngocutaneous fistula (PCF) can occur if aerodigestive tract is breached simultaneously

13. Lymphedema / Seroma

• Seroma: Accumulation of serous fluid in dead space
• Managed with prolonged drain placement

14. Carotid Artery Complications

• Carotid blowout: Rare but life-threatening; risk increased by wound infection, prior RT, and wound dehiscence
• Carotid sinus syndrome: Manipulation of carotid sinus → bradycardia/hypotension intraoperatively

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Summary of Nerve Injuries at a Glance

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• Cummings Otolaryngology Head and Neck Surgery, 7e, Chapter 118 (pp. 2289-2381) - Cervical Lymph Node Groups, Neck Dissection, Complications of Neck Dissection
• Sabiston Textbook of Surgery, p. 1354 - Neck Dissection classification and selective SND types
• Scott-Brown's Otorhinolaryngology H&N Surgery - Classification table (TABLE 18.2)
• Fischer's Mastery of Surgery, 8e, p. 1105 - Lymphatic Drainage of Neck, Levels I-VIIAbove is your complete, detailed, textbook-sourced answer. Here is a quick orientation to what's covered:

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What's Covered (Summary)

PART 1 - Cervical Lymph Node Classification (AAO-HNS Level System)

• 7 levels (I through VII) with ALL surgical boundaries in tabular form
• Each level broken down into sublevels (Ia/Ib, IIa/IIb, Va/Vb)
• Boundaries in 4 directions: Superior, Inferior, Anterior/Medial, Posterior/Lateral
• Primary drainage sites for each level
• Illustrated with the Cummings Otolaryngology textbook diagram

PART 2 - Neck Dissection Types

• Radical (RND): Levels I-V + SAN, IJV, SCM all removed
• Modified Radical (MRND Types I, II, III): Levels I-V with progressive preservation of SAN → IJV → SCM
• Selective (SND): Site-specific - Supraomohyoid (I-III), Lateral (II-IV), Posterolateral (II-V), Central (VI)
• Extended: Beyond standard RND limits
• Site-to-dissection matching table for clinical use

PART 3 - Complications

• Intraoperative: Hemorrhage, air embolism, pneumothorax, thoracic duct injury
• Postoperative: Chylous fistula (most detail with management), hematoma, facial/cerebral edema (bilateral IJV ligation), nerve injuries (CN XI-shoulder drop being the most significant), Horner's syndrome, carotid blowout, wound breakdown