Modified radical neck dissection (MND) is a complicated operation. The risk of a life threatening complication is negligible, but there are risk to the procedure. We’ll review the major issues. Overall the risk a of self-limiting complication such as wound infection, seroma formation, limited shoulder motion or temporary nerve dysfunction is about 10%. The risk of a permanent problem such as poor shoulder function or chronic pain issues is less than 5%.
When MND is performed the major blood vessels, nerves and muscles are exposed on the side of the dissection. The lymph nodes are removed and injury to the listed structures is possible. Injury to large blood vessels is very rare and generally easily dealt with, but significant bleeding or stroke have been reported. Injury to muscles is not a significant issue. The most important permanent risk of surgery involves nerve injury. The nerves at risk with MND fall into two broad categories.
- Sensory nerves
- Motor nerves
Three large sensory nerves are encountered with MND. These give sensation to neck, anterior shoulder, lower jaw area and the area near the lower part of the ear. These nerves are commonly stretched or divided during the operation. Post-op patients experience variable loss of sensation or blunted sensation around the wound and in the areas described. Over time this improves and the loss of sensation resolves. This may take months and occasionally, may be a significant bother to the patient. Rarely the return of sensation may be painful and chronic pain syndromes may develop. The risk of this is less than 1%.
A more important risk involves the motor nerves in the area. Seven nerve groups are considered.
- The nerve to the lower lip (Ramus Mandibularis). This nerve is not really in the area of dissection, but it can be compressed by retractors during the procedure. If it is injured, the patient could have difficulty moving the corner of the lower lip. This is generally a minor cosmetic issue and almost always resolves within a few weeks.
- The Hypoglossal Nerve. This nerve controls the side of the tongue. If it is injured the tongue may deviate with protrusion. Injury to this nerve is quite rare as it is easily seen and few lymph nodes are near it.
- The Vagus Nerve. This large nerve runs the length of the neck along the major blood vessels. Lymph nodes may be intimate to it. It is commonly manipulated during surgery. Injury to this nerve will cause significant voice problems because the recurrent laryngeal nerve is a branch of this nerve. Injury may results in a paralyzed vocal cord.
- The Phrenic Nerve. This nerve runs deep in the neck. It controls the diaphragm which is important in breathing. Injury to this nerve is very rare. When it occurs it it rarely an issue for the patient.
- The Brachial Plexus. This is actually a nerve bundle which controls the muscles of the shoulder arm and hand. This nerve bundle is very deep in the neck. Injury is very rare. Arm weakness and and poor motor control could occur with injury.
- The Spinal Accessory Nerve. This nerve is high and very shallow in the neck. It controls a large muscle of the shoulder called the trapezius. Injury to this nerve will compromise shoulder function especially raising the shoulder. This nerve is difficult to identify and while injury is uncommon, it is an important source of problems for affected patients.
- The cervical sympathetic plexus. This is a small bundle of nerves on either side of the back bone that are responsible for a variety of unconscious neurologic function. Rarely, this plexus may be important if cancer penetrates deeply (inferiorly) down the neck through the thoracic inlet into the upper chest. Dissection in this area could result in a Horner’s syndrome. On the affected side, patient experience difficulty raising the eyelid, diminished sweating on that side of the face and a constricted pupil. This problem has been reported after extensive dissection around the carotid artery as well.
The risk of permanent injury to one of these nerves is less than 3%. Physical therapy can be very helpful in these situations. We use nerve monitoring techniques during the procedure to verify these nerves are intact at the conclusion of the procedure.
A final risk of surgery involves the Thoracic duct. This is a large thin-walled lymphatic vessel that is present at the base of the neck and empties lymphatic fluid from the body into the blood stream at the jugular vein on the left side of the neck. Injury may result in leakage of lymphatic fluid into the wound resulting in significant (sometimes massive) swelling. A second surgery is usually required to take care of this problem. This problem occurs in about 3% of patients and is an issue only with left MND.
Full recovery from the surgery is about a month to 6 weeks. Some degree of swelling is very common. Local discomfort is readily controlled with oral medication. Most patients take narcotic pain medication for 1-2 weeks. Most patients have 2 post-op visits. At 10 days and 4 weeks. MND is very effective treatment for regional node disease. More than 60% of patients have their disease controlled with MND.