This can be done on one or both sides. It can also be done in the central and/or lateral neck depending on the disease present. Sometimes we remove the lymph nodes because there is obvious cancer in them while other times we remove them to catch early microscopic cancer. The need for and extent of neck dissection has changed over the last decades and very much depends on the specific cancer present. It is important that the dissection is done thoroughly the first time rather than node "plucking" which is common among less experienced surgeons.
If a lateral neck dissection is performed, one can expect a drain to remain in place for a few days. With central neck dissection, we do not use drains and patients can be discharged the same day as surgery.