The submandibular gland, like the parotid gland, is one of the major salivary glands. On either side, the gland sits under the jaw bone (sub=under, mandible=jaw).
The gland makes saliva which empties via Whartons duct into the floor of the mouth just behind the lower front teeth.
The submandibular gland can cause problems due to inflammation or due to a lump within it.
Inflammation of the submandibular gland (sialadenitis) is usually caused by a salivary calculus. This is a stone that forms in the gland and moves toward the duct. The smaller the stone is, the further down the duct it can travel. Often the stone will pass all the way along the duct and into the mouth. If it is too large, it may get stuck part way along the duct and lead to obstruction of the duct. This obstruction causes an increase in pressure within the gland, which causes pain and swelling (inflammation) under the jaw, particularly at meal times. Occasionally this can be complicated by infection. If the inflammation recurs, it can cause scarring and chronic problems within the gland. If such blocking of the gland can be found early, sometime just the stone can be removed. If the problem becomes chronic, usually the entire gland has to be removed.
Tumours (lumps) of the submandibular gland are less common than in the parotid, and are more likely to be malignant than those in the parotid gland. A lump within the submandibular gland usually requires surgery. This is often preceded by a needle biopsy. If the biopsy shows a malignancy, often a more extensive operation is required ( see neck dissection). If the tumour is felt to be benign, removal of the gland alone is usually all that is required.
Removal (extirpation) of the submandibular gland is not a minor operation. It requires a general anaesthetic, and usually means staying in hospital overnight. A drain is left in the surgical site overnight and in most cases is removed the next morning, prior to discharge from hospital.
Specific complications of the surgery, other than infection, bleeding and wound complications, include the effects on several key nerves in the area.
The marginal mandibular nerve is a branch of the facial nerve which moves the face. This nerve passes directly over the submandibular gland and needs to be moved out of the way during surgery. If this nerve is bruised or traumatised by the surgery, it may not work normally, which causes a weakness of the lower lip. Thankfully this effect is usually temporary but occurs in about 15% of cases, even if only to a minor extent
The lingual (sensory) and hypoglossal (motor) nerves are always seen during removal of the gland as they lie directly underneath (deep) to the gland. Injury to either of these nerve will effect either sensation or movement of the tongue on the side of the surgery. This complication occurs less than 10% of operations.
Recovery from this surgery is often quite uncomfortable. It is not unusual to need to use quite strong painkillers for up to one week following removal of the submandibular gland.