Rationale for modifying neck dissection. 
Neck dissection is one the most commonly performed operations in head and neck surgery.  Better understanding of the structure and patterns of lymphatic flow in the neck has transformed this operation into a more selective and less morbid treatment.  Rationale for this operation and modifications of it in different clinical scenarios such as node negative, node positive and radiated neck are detailed in this article.  Recommendations are made based on the available evidence.