Overview of Submandibular Excision
Salivary glands are special glands in your body that create saliva, or spit. Saliva has many important jobs. It helps keep your mouth and throat moist, which helps with swallowing, talking, and tasting food. Saliva also starts the process of breaking down food when you eat. Additionally, it helps protect your teeth from cavities and promotes healing of the teeth.
There are three main pairs of salivary glands in your body. These are known as the parotid glands, the submandibular glands, and the sublingual glands. The submandibular glands produce a mix of different types of saliva. Even though the parotid glands are the biggest, the submandibular glands actually make the most saliva.
Besides these three main pairs, you also have many smaller salivary glands scattered throughout the lining of your mouth and throat. Recently, scientists discovered a new set of these smaller glands located in the nasopharynx, which is the area at the back of your nose.
Anatomy and Physiology of Submandibular Excision
The submandibular glands sit within a part of the neck sometimes referred to as the submandibular triangle. The edges of this area are determined by different parts of the neck and jaw, like the jawbone and the neck and throat muscles. The deeper part of this triangle (the “floor”) is formed by a muscle of the jaw called the mylohyoid muscle, and the outer border is shaped by the platysma muscle, a muscle present in the neck and shoulder.
There are also several critical structures that reside within this region of the neck. When a surgeon operates in this space, they need to be very careful to avoid damaging a crucial nerve called the marginal branch of the facial nerve. This nerve branches from another critical facial nerve within a gland in the face (the parotid gland) before it courses down and beyond the jawbone into the submandibular space within a deeper layer of the cervical fascia – a type of connective tissue. This nerve is closely associated with the superficial aspect of the submandibular gland as it courses forward and upward toward the corner of the mouth.
The hypoglossal nerve, another important nerve that controls tongue movements, also courses through this space. Similarly, the lingual nerve is found in this area and provides sensory feedback from the anterior part – the front two-thirds – of the tongue, like touch, pain, and temperature sensation. In addition, another nerve for taste (the chorda tympani nerve) travels with the facial nerve through the internal ear before branching off and joining the lingual nerve.
A chief blood vessel known as the facial artery also courses through this area. After branching off from another significant artery (the external carotid artery), it travels around a muscle and through the gland before it exits into a notch of the jawbone. Each submandibular gland has an associated duct (Wharton’s duct) which extends upward and inward from the gland into the floor of the mouth.
The production of saliva by the submandibular gland is controlled by the autonomic nervous system, the part of the nervous system that controls subconscious body functions like heart rate and digestion. The gland’s functions are influenced by two main types of nerves called parasympathetic and sympathetic. The sympathetics, originating from a mass of nerve cells in the neck, decrease blood flow to the gland and reduce saliva production, while the parasympathetics, coming from a part of the brainstem (the pons), increase blood flow and induce saliva production.
Different illnesses can affect the submandibular gland. These can be sudden processes, such as blockages in the ducts that drain saliva from the gland, or infections of the gland. These typically infect one gland and are often caused by types of bacteria such as Staphylococcus aureus or Haemophilus influenzae. More long-term conditions include tumors, autoimmune diseases, diseases causing abnormal deposits of substances like amyloid, or mysterious enlargements of the gland without any identified cause.
Why do People Need Submandibular Excision
The most frequent reason for the removal of the submandibular gland, located beneath the lower jawline, is a salivary stone that creates a blockage in the gland’s duct and results in infection. If the stone is present solely within the duct, the stone might be removed via the mouth. Yet, many people with this condition undergo repeated episodes of blockage and infection, which don’t typically resolve with noninvasive treatments. In these cases, removing the submandibular gland can solve the problem.
Another reason for removing the submandibular gland is the existence of a benign (noncancerous) growth within the gland. About three-quarters of submandibular gland growths are benign, with the most common type being a pleomorphic adenoma, and around a quarter are malignant (cancerous), often being mucoepidermoid carcinoma, adenoid cystic carcinoma, or adenocarcinoma. Before embarking on removing the gland for a growth in the gland, a thorough pre-surgery examination is important. This is due to the fact that a cancerous growth should not be handled only by removing the gland. In cancerous cases, a more comprehensive neck surgery is usually needed depending on the kind and stage of the tumor.
Persistent sialorrhea, or excessive saliva, is another reason for removing the submandibular gland. In such cases, the procedure is typically carried out on both glands and may be accompanied by the pinching off of the parotid ducts. However, excessive drooling may also be managed with Botox injections, which have been found to be effective and readily tolerated, so surgical removal is usually held back for persisting cases.
A thorough evaluation is essential before surgery. This involves obtaining a complete history and conducting a physical examination, paying attention to when symptoms started and how they have advanced, whether issues are present on one side or both, and signs and symptoms related to autoimmune, inflammatory, or viral conditions. Past radiation or radioactive iodine treatment should also be identified. An examination of the entire head and neck, with special attention to the mouth area and a close inspection of the neck for any abnormal growths or lesions, is then carried out. Function and symmetry of the facial nerve, particularly around the mouth corners, should be checked.
Before surgery, an imaging scan of the submandibular gland, either by ultrasound or CT scan, is needed to check for a growth and identify any stones. If there’s a chance of a growth based on the medical history, examination, or imaging, then a fine-needle aspiration (a type of biopsy) of the suspected gland growth should be done and the results should be analyzed before surgery to ensure a malignant growth is not present.
When a Person Should Avoid Submandibular Excision
There are certain situations where removing the submandibular gland, which is a salivary gland under the jaw, may not be safe or suitable. One such situation is if there is a cancerous tumor, or strong suspicions of one, in the gland. In this case, simply removing the gland won’t be enough.
Also, for patients with other serious health problems, this kind of surgery might not be safe. These health problems might make it risky for them to undergo the operation. Majority of the time, this surgery is performed while the patient is completely asleep under general anesthesia. However, in some very unique cases, the surgery is done with the patient awake, using local anesthesia that numbs only a certain area of the body.
Equipment used for Submandibular Excision
The essential tools needed for this procedure usually involve a kit specifically designed for head and neck soft tissue surgeries. Some doctors prefer to use special instruments known as sialendoscopes, which are small, flexible tubes equipped with a tiny camera to view the salivary glands. They might also use facial nerve monitors or stimulators to ensure that the nerves in your face are functioning properly during the surgery. However, these additional tools are not absolutely mandatory.
Preparing for Submandibular Excision
In simple cases where a person is undergoing surgery on their head or neck, antibiotics usually aren’t needed. The patient is then carefully positioned lying flat on their back (supine) on the surgery table. A roll is placed under their shoulders to gently tilt their head back and to one side, away from where the surgery will be done.
Often, surgeons will turn the surgery table so it’s at right angles to them, allowing them plenty of space to operate. Some surgeons might choose not to turn the table, but instead, move it towards the patient’s feet. This positioning is such so that the surgeon has unobstructed accessibility and space to do their work.
Next, the area from the patient’s nose-lip corner (nasolabial angle) to their collarbones (clavicles) on the side of the operation is cleaned and covered with surgical drapes to maintain sterility. The corner of the mouth is kept visible. This way, the medical team can watch for any signs of involuntary muscle twitching during the surgery, which could indicate a problem.
How is Submandibular Excision performed
Your surgeon will first numb the operation area on your neck with a local anesthetic. Then, they will make a small cut, about one inch long, on the lower part of your neck, in the area below your jawbone. They’ll use a natural crease in your skin for this if one is available. If there is a tumor to remove as well, they might have to make a slightly larger cut, lower down on your neck. The surgeon will make sure to make the cut low enough on your neck to give them more room to work and to make the scar less noticeable.
Next, your surgeon will gently lift the skin on your neck to access the area where they’ll be working. They need to be careful because there’s a nerve near here, called the marginal mandibular nerve, that they need to avoid damaging. To protect this nerve, they have two options: some surgeons might choose to keep the skin in place here, while others might lift the skin up and then split the neck muscles vertically to find the nerve.
The surgeon then has to avoid accidentally causing any damage to the nerve while they’re carrying out the operation, being particularly careful if they’re using an electrocautery device, which uses heat to cut or remove tissue. Depending on the surgeon’s preference, they might decide to identify and follow a nerve near the site of the operation to avoid damaging it, or they might decide to lift up the skin and work underneath it. The blood vessels in this area will be tied off and secured to stop the flow of blood and then moved out of the way. The surgeon will then start to separate the submandibular gland, a gland in your mouth that produces saliva, from the jawbone.
The dissection is then done at the front of the gland, and they’ll identify a muscle called the digastric muscle. They need to keep sight of another muscle, the mylohyoid muscle, to avoid injuring two nerves, the hypoglossal and lingual nerves. The surgeon will follow along the posterior belly of the digastric muscle to the back of the submandibular gland and avoid injuring the hypoglossal nerve and branches of the external carotid artery. In this step, a vein at the back of the gland may be divided.
The surgeon then moves the submandibular gland backward and downward away from the mylohyoid muscle. A special tool is used to push the mylohyoid muscle forward to give the surgeon a better view of the two nerves and the submandibular duct. This duct, which carries saliva from the gland into the mouth, and submandibular ganglion, a group of nerve cells, will then be tied off. If there are any stones in the submandibular duct, the surgeon will take care to tie it off after the stones and then remove them.
Lastly, the surgeon will tie off one artery near the digastric muscle and remove the gland. Depending on the surgeon’s opinion and the size of the cavity after removal, a drain may be placed to prevent fluid accumulation. The wound is then closed as per the surgeon’s usual practice.
It’s worth noting that although the procedure described above is the most common way to remove the submandibular gland, there are other less traditional ways to do it too, such as using a special robotic system or other endoscopic techniques. These alternative methods can be done through several types of slit made in different locations, including inside the mouth, behind the ear, or along the neck’s hairline. However, these newer techniques are limited due to the specialized equipment and surgical expertise required.
Possible Complications of Submandibular Excision
When having surgery on the submandibular gland (one of the salivary glands located beneath the lower jaw), great care is taken to protect the marginal mandibular nerve. This nerve controls some facial movements, and any damage could cause temporary or permanent weakness. In a set of procedures studied, about 15.6% of patients experienced temporary nerve weakness, while about 2.2% had permanent weakness.
Issues related to wound healing after this type of surgery are similar to those seen with other neck surgeries, ranging between 7% and 22% of cases. Additionally, less than 2% of surgeries resulted in injury to the hypoglossal or lingual nerves – nerves that control the tongue’s function.
A condition known as “xerostomia” — dry mouth due to reduced or absent saliva flow — is usually not common after removing one submandibular gland. Yet, how this surgery affects saliva production overall is still being studied.
In the days after the surgery, some people may develop a hematoma, which is a blood-filled swelling. It’s also possible for significant bleeding to occur from the facial artery, which could affect your airway. However, these are rare complications.