Structure Preserved in Radical Neck Dissection
None of the listed structures are preserved in a radical neck dissection. In a radical neck dissection, all of the structures mentioned - internal jugular vein, sternocleidomastoid muscle, spinal accessory nerve, submandibular salivary gland, and posterior belly of the digastric muscle - are removed. 1
Understanding Radical Neck Dissection
Radical neck dissection is a comprehensive surgical procedure that involves:
- Removal of all lymph node groups (levels I-V)
- Removal of the internal jugular vein
- Removal of the sternocleidomastoid muscle
- Removal of the spinal accessory nerve
- Removal of the submandibular salivary gland 1, 2
This procedure was first described by Crile in the early 20th century and was later standardized by Martin, who established the technical precepts that were followed until the latter part of the 20th century 3.
Distinguishing Between Types of Neck Dissection
It's important to differentiate between the various types of neck dissection:
Radical Neck Dissection: Removes all lymph node groups (levels I-V) along with the internal jugular vein, sternocleidomastoid muscle, spinal accessory nerve, and submandibular salivary gland 1, 2
Modified Radical Neck Dissection: Preserves one or more of the non-lymphatic structures (internal jugular vein, sternocleidomastoid muscle, and/or spinal accessory nerve) while still removing all lymph node groups 1, 3, 4
Selective Neck Dissection: Removes only specific lymph node groups at highest risk for metastases based on the primary tumor site 1
Clinical Implications and Anatomical Considerations
The posterior belly of the digastric muscle is often used as an important landmark during neck dissection as it helps define boundaries in surgical neck dissection and contributes to the carotid, submandibular, and submental triangles 5, 6. However, in a radical neck dissection, this structure is not preserved.
The removal of these structures in radical neck dissection leads to significant functional implications:
- Removal of the spinal accessory nerve results in shoulder dysfunction
- Removal of the sternocleidomastoid muscle causes cosmetic deformity
- Removal of the internal jugular vein may lead to increased intracranial pressure and facial edema 2
These functional implications have led to the development of modified techniques that preserve these structures when oncologically appropriate 3, 4.
Indications for Radical Neck Dissection
Radical neck dissection is typically recommended for patients with:
- Extensive nodal disease (N3)
- Multiple palpable nodes
- Nodes larger than 3 cm in diameter
- Disease in the posterior triangle
- Failed radiotherapy to the neck 1, 4
In modern practice, modified radical or selective neck dissections are often preferred when oncologically appropriate to reduce morbidity while maintaining equivalent disease control 1, 3.