Trigeminal nerve injuries may occur as a result of many facial, oral-surgical, and dental procedures despite the practitioner providing the highest level of care. Nerve injuries from third molar extraction, dental implant placement, endodontic therapies, orthognathic surgery, local anesthetic injection, or trauma are a known risk during many procedures, even when performed perfectly.
Symptoms are wide ranging, but potentially devastating. Neurosensory deficits caused by dentoalveolar procedures can interfere with speaking, eating, drinking, smiling, and even intimacy. These injuries may also develop into debilitating neuropathic pain syndromes without early intervention.1 While most injuries are transient and resolve on their own, in some cases nerve damage can have a long-lasting impact on the patient’s quality of life.
Patients with persistent or evolving symptoms may benefit from evaluation and treatment by an oral maxillofacial surgeon trained in diagnosing and addressing nerve damage. Innovative solutions in nerve care such as processed nerve allograft and evolving nerve repair techniques offer safe, effective, and consistent patient outcomes.
Time is one of the most crucial components of success in the management of trigeminal nerve injuries.2 Dentists, therefore, play a vital role in ensuring patients are able to seek the prompt attention they need. Diagnosis and repair of the trigeminal nerve in a timely fashion results in greater odds of improvement.3,4 Surgical intervention to repair trigeminal nerve injuries should occur on or before 90 days following injury, which means a prompt referral is paramount.
The Importance of Patient Interaction
If there is a witnessed nerve injury at the time of the procedure, immediate referral may be appropriate. However, it often is not immediately clear that nerve damage has occurred. The best way to ensure symptoms are recognized early is a protocol for regular interaction with the patient.
I always stress the necessity of calling patients the evening following a procedure. If they are still unable to feel the area, you may reasonably conclude they are slow metabolizers of the anesthetic. But you should plan to call back the next day, and into the days following, to assess their progress and gather more information. Not only does this demonstrate the highest standard of care, but it also positions you to identify potential symptoms of nerve damage as soon as possible.
Given the short window of time for optimum outcomes and the patient’s lack of familiarity with nerve injuries and their effects, waiting for the patient to contact you regarding lingering changes in sensation or pain can result in a significant delay in diagnosing nerve damage. The patient might also disregard numbness for long enough that it becomes pain, as a neuroma develops at the site of the injury.
Symptoms to look out for may include:
- Persistent loss or decrease of sensation in the lip, jaw, chin, cheek, or tongue
- Persistent or intermittent pain in the lip, jaw, chin, cheek, or tongue
- Difficulty chewing, swallowing, or drinking
- Biting the lip, cheek, or tongue
- Drooling or the sensation of drooling
- Loss of or change in taste
- Difficulty speaking, kissing, or shaving
Finding the Words
Few patients are aware of the prevalence of nerve injuries and their myriad effects, which presents a language barrier in diagnosis. A lack of vocabulary to describe loss of sensation or the onset of pain contributes to this challenge. For example, two patients may both describe their lip, chin, or tongue as “numb,” but in reality they may have different injuries and experience different degrees of sensation.
Because patients do not have the vocabulary of the healthcare provider to describe what they are feeling, practitioners must translate their descriptions into clinically meaningful information. Asking questions to determine the nature or severity of numbness and the practical impacts these deficits are having on the patient such as drooling or loss of taste and taking notes is not only helpful in identifying an injury that needs further care but can also offer beneficial insight to the nerve specialist later on.
After several days or a week of loss of feeling or abnormal sensation, an office visit to objectively assess the situation and set a baseline for improvement—or a lack thereof—is crucial.
Objective Assessments
Aligning the patient’s description of his or her experience with objective assessment is an important next step so progress can then be measured. Often, the patient experiences a range of altered sensation. Basic assessments like a fine-touch test, a directional stroke test to see if the patient can perceive an object (such as a cotton swab) moving across the tongue, lip, and chin, or a pinprick to check the perception of pain will provide valuable information on change or loss of sensation to the area.
Even after I conduct these tests, a lengthy process of further assessment is a key part of the care I provide to each of my patients. Our primary responsibility as care providers is to do no harm, so rushing a patient to surgery that may not be necessary should be avoided. At my practice, we take our time to conduct serial neurosensory examinations in two-week intervals, including two-point discrimination tests and detailed mapping of the area of paresthesia over time, to see if symptoms improve and determine appropriate next steps for the best outcome.
From the patient’s first visit to my office, it can take up to two months before a procedure is performed. With the 90-day window in mind, that means the referral should occur within the first four to six weeks following the initial injury.5
Other Protocols
In addition to being prepared to refer the patient to a specialist, the referring provider may do other things to help the patient once an injury has become apparent.
Putting the patient on a Medrol Dosepak will decrease swelling. If compression of the nerve has resulted from a compartment syndrome, the steroids will help to relieve symptoms, indicating that surgical intervention may not be necessary. Additionally, B-complex vitamins help with nerve regeneration and may have an analgesic affect.
These steps have clear physical benefits but serve an important psychological purpose as well. Nerve injuries can be debilitating and disorienting. They also may take a long time to diagnose and even longer to see improvement or results. So, these treatments can help patients mentally in knowing that they are taking steps to address their condition and keep things moving forward.
The Best Possible Outcome
The odds of improving outcomes for patients, through surgical intervention, decreases by 5.8% per month following the 90-day recommended surgical treatment window.4 Early diagnosis and treatment can mean the difference between patients being able to eat, drink, and speak normally or not.
When you take charge of your patients’ health and consult an oral maxillofacial surgeon promptly if you feel a trigeminal nerve injury may have occurred, you give them the best chance at being restored to the highest possible quality of life.
References
- Yampolsky A, Ziccardi V, Chuang SK. Efficacy of acellular nerve allografts in trigeminal nerve reconstruction. J Oral Maxillofac Surg. 2017;75:2230-2234.
- Zuniga JR, Mistry C, Tikhonov I, et al. Magnetic resonance neurography of traumatic and nontraumatic peripheral trigeminal neuropathies. J Oral Maxillofac Surg. 2018;76:725-736.
- Bagheri SC, Meyer RA, Khan HA, et al. Retrospective review of microsurgical repair of 222 lingual nerve injuries. J Oral Maxillofac Surg. 2010;68:715-723.
- Bagheri SC, Meyer RA. When to refer a patient with a nerve injury to a specialist. J Am Dent Assoc. 2014;145:859-861.
- Zuniga JR. Sensory outcomes after reconstruction of lingual and inferior alveolar nerve discontinuities using processed nerve allograft—a case series. J Oral Maxillofac Surg. 2015;73:734-744.
Dr. Petrisor is an assistant professor of oral and maxillofacial surgery at the Orgeon Health & Science University (OHSU) School of Dentistry. He is a board-certified surgeon with training in microvascular reconstructive surgery, head and neck surgery, and oral and maxillofacial surgery. He holds a dental degree from OHSU and a medical degree from the University of Texas Southwestern Medical School. In addition to medical school, he also completed his residency at the University of Texas Southwestern Medical Center and Parkland Memorial Hospital in Dallas. Following his residency, he completed a fellowship in head and neck surgery and microvascular reconstructive surgery at Louisiana State University Health Sciences Center in Shreveport. He then completed an additional fellowship in microvascular reconstructive surgery at the University of Florida-Jacksonville. He can be reached at petrisor@ohsu.edu.
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