Nerve Injury

Inferior alveolar and lingual nerve injury-


Lingual nerve injury or damage can result in anesthesia (numb tongue), paresthesia (tingling), or dysesthesia ( pain and burning ) in the tongue and inner mucosa of the mouth. This can be due to complication of tooth extraction of the wisdom teeth ( third molar ) or dental anesthetic injection (nerve block) for fillings, crowns. It result in a chronic pain syndrome or neuropathy.  If the inferior alveolar nerve is involved, numbness of the lip may result.
Some people have injury to the inferior alveolar nerve.    The injury can result in anesthesia, paresthesia, or dysesthesia of the chin, lower lip, and the jaw.  This nerve can be injured by injection, but is more commonly injured during wisdom tooth extraction.  It can also be injured by root canal procedures, other tooth extractions and with placement of implants. 

Surgical procedures in the area of the lingual are the most common cause of nerve damage, resulting in temporary or permanent loss of sensation or pain in the distribution of the nerve.   Sometimes the inferior alveolar nerve is injured, and sometimes the lingual nerve.   Both can be bothersome injuries, but in general the inferior alveolar nerve injuries (mucosa and lip numbness) are tolerated better than the lingual nerve injuries (tongue and inner gingival mucosa).  
Following damage, the result can be total loss of sensation, change of sensation, continual or constant pain, or a combination of these.  Some of these symptoms can be relieved by surgical intervention, as discussed in the treatment options.  
As a rough guide, if your surgeon/dentist identified during the procedure that the nerve was severed, you should have been referred immediately for surgical repair. The odds and completeness of recovery depend on the injury and the patient including age etc.  Surgical repairs done within the right time frame (10-12 weeks) can be expected to attain about 75% of normal sensation in about 70% of the cases.   The longer delay until surgery, the lesser the percentage of success such that it is rarely recommended after 9 months.  With partial numbness it can be hard to make the decision, which should probably be made within 4-5 months.  
Both the inferior alveolar nerve and the lingual nerve can be repaired, including the portion of the inferior alveolar nerve that travels within the bone.  The rates of recovery of the inferior alveolar nerve is better than those with the lingual nerve. 

Lingual Nerve Injury from Anesthetic Injections

 Nerve damage from an inferior alveolar nerve block is a rare complication.

Damage to the lingual nerve results in pain within the tongue and along the mucosa on tongue side of the teeth (inner buccal mucosa).  The pain can be burning, dull, achy or a combination.  You may also have numbness as the only symptom, or can have a combination of numbness and pain.  

There is not an established treatment protocol.  Most (at least 85%) of these injuries resolve on their own, so most dentists just try to calm your fears and tell you that everything will be fine.  They will be right at least 85% of the time.

Many physicians who deal with nerve injuries recommend a course of steroid therapy if the injury is recent.one would want to weigh the risks of taking a short course of steroids (which is quite small), against the benefit that steroids might give to prevent nerve scaring (which is unknown).

The mechanism of injury is not known for sure.  It includes trauma from the needle itself.  There is one source that notes that during the procedure, the needle tip may contact bone and become bent.  If this needle had pierced the lingual nerve on the way through, it may cause significant physical trauma as it is withdrawn.  Many suspect that the injury is due to an intraneural injection of the local anesthetic, that is, an injection directly into the nerve itself.  While the local anesthetic deposited just outside the nerve is relatively harmless, it may be neurotoxic if injected directly into the substance of the nerve itself.  It may disrupt the nerve fibers and cause intraneural fibrosis

If you feel you must have a nerve block, have it done with a 25 gauge needle, and setup hand signals with the dentist so that if you feel the needle hit one of the nerves ( which you can tell by the "shock" sensation), the dentist (or other operator), can withdraw and redirect the needle so as to try to avoid the injury.  This technique is described in one of the textbooks on dental anesthesia.  

Treatment-

Surgery

Surgery is often used with success to treat lingual nerve injuries from trauma or tooth extraction.  Surgery for lingual nerve damage due to local anesthetic injection in the course of dental work is usually not recommended, and the jury is still out as to whether it has any place in the management of this type of injury.  

For trauma and tooth extraction injuries, the literature indicates good results from early intervention, so it is important to see an oral surgeon early in order to access whether you are a candidate, and when surgery might be appropriate.  Most data indicates that the surgery should be done within 6 months of the date of injury, and many recommend earlier intervention.  

                                        Drug Options

Carbamazepine - Thought to be effective for trigeminal neuralgia, but limited success for other painful sensory neuropathies.  Oxcarbazipine is an analog that is better tolerated in some patients.

Gabapentin (Neurontin®)

Neurontin is one of the newer anti-seizure medications that has been used with some success in treating chronic nerve pain.  It is a very popular drug right now, although it's mechanism of action is unknown. It does provide some relief, and not had too many side effects.optimal dosage is still being determined.