Lingual Nerve Injury

Steven B. Graff-Radford, DDS, Randolph W. Evans, MD

Disclosures

Headache. 2003;43(9) 

In This Article

Therapy

Nonsurgical

Corticosteroids

Immediately following injury, there may be reason to consider high-dose corticosteroids to reduce immune inflammatory reaction. This has been studied in neuritis involving the seventh nerve (Bell palsy), but not in the developing sensory nerve deficit. It is, however, common for neurosurgeons to prescribe corticosteroids following intracranial surgery. Additionally, in a patient in the prone position, the use of an NMDA antagonist may be beneficial. Further research is needed in this arena.

The therapy for trigeminal dysesthesia is aimed at reducing peripheral nociceptive inputs and simultaneously enhancing central nervous system pain inhibitory systems.[67]

Topical Applications

The use of topical therapies as not been well studied. There is some evidence that capsaicin applied regularly will result in desensitization and pain relief. The recommended dose is 5 times per day for 5 days, then 3 times per day for 3 weeks. If the patient cannot withstand the burning produced by the application, the addition of topical local anesthetic, either 4% lidocaine or EMLA, is useful. Clonidine can be applied to the hyperalgesic region by placing the proprietary subcutaneous delivery patch where it is most tender. Alternatively, the use of 4% gel can be compounded and delivered over a larger area. For local intraoral application, a neurosensory stent has been created. After an oral impression, an acrylic stent is manufactured to cover the painful site.[67] The topical agent is applied to the gingival surface and placed intraorally 24 hours per day.

Topical clonazepam (0.5 to 1.0 mg 3 times per day) has been effective at reducing burning oral pain.[68] Patients were instructed to suck on a tablet for 3 minutes (and then discard it) 3 times per day for at least 10 days. Serum concentrations were minimal (3.3 ng/mL) 1 and 3 hours after application. Woda hypothesized a peripheral not central action at disrupting the neuropathologic mechanism.[66]

Procedures

Neural blockade is very effective in differentiating sympathetically maintained pain (SMP) from sympathetically independent pain. It may also be effective in controlling SMP if used repetitively. Stellate ganglion blocks, phentolamine infusion, and sphenopalatine blocks have been described as useful in obtaining a chemical sympathetic block. The authors have not had significant benefit using phentolamine infusion in facial pain. This is supported by Scrivani et al who used 30-mg infusions without benefit.[67]

Lidocaine infusion (200 mg over 1 hour) may be used therapeutically in various forms of neuropathic pain.[68,69] It is suggested that response to intravenous lidocaine may predict who responds to the lidocaine analog, mexiletine. Sinnott et al used an animal model to demonstrate that minimal lidocaine concentration (2.1 mg/mL) is needed to abolish allodynia.[70] They also describe a ceiling effect. Many animals with experimentally induced allodynia did not obtain persistent relief. They suggest separate physiological mechanisms, with differing pharmacologies, may account for variability, and they suggest there are different aspects of neuropathic pain.

Pharmacology

Tricyclic Antidepressants. It is well documented that tricyclic antidepressants are effective in many pain problems. Solberg and Graff-Radford have studied the response of amitriptyline in traumatic neuralgia. It is noted that the effective range is 10 to 150 mg per day usually taken in a single dose at bedtime.[32] Many antidepressants may be used.

Membrane Stabilizers. These medications include the antiepileptic agents, lidocaine derivatives, and some muscle relaxants. They have been classically used in intermittent, sharp, electriclike pains. The newer generation of medications that affect -aminobutyric acid appears to be effective in continuous as well as intermittent pain. These include gabapentin, topiramate, and zonisamide.[67]

Behavioral Strategies

Before beginning therapy, it is common to perform a behavioral assessment with appropriate testing. Following the behavioral evaluation, management is directed at the factors that may affect treatment and determine the most appropriate interventions. Consideration should be given to the following factors: (1) behavioral or operant, (2) emotional, (3) characterlogical, (4) cognitive, (5) side effects, (6) medication use, and (7) compliance. Therapy such as cognitive and behavioral management techniques, relaxation, and biofeedback with psychotherapeutic and psychopharmacological interventions may be useful.

Surgical

Microsurgical techniques for nerve repair have been used for many years. There is little standardized manner in assessing outcome, and the numbers studied are very limited, especially when it comes to the lingual nerve. Repair may entail decompression, direct suture, or grafting. As mentioned previously, using an animal model, Robinson suggested excision and apposition with suture was the most effective repair procedure.[71] They have prospectively assessed 53 patients, and although on an individual basis the outcome is variable, there was some benefit in most patients. Light touch improved from 0% to 51%, pinprick response increased from 34% to 77%.[5,71] About half of these patients had some continuity in the nerve despite the lack of recovery. The nerves were found trapped in dense scar tissue and often a neuroma was evident. Unfortunately, there was little benefit in the dysesthesia or pain that was present. Gregg has reported a 49% reduction in pain in 31 patients following lingual nerve repair.[72] Pogral and Kaban also reported good pain reduction following repair.[2] In 1996, Robinson reported 13 patients in whom the lingual nerve was repaired by apposition and epineural suture. The mean duration postinjury was 16 months.[71] There was some sensory restoration and some taste recovery. Patients' subjective assessment of the value of the surgery ranged from 0 to 10 with a median of 7.

Microvascular decompression is very effective in the compression neuropathies. Trigeminal neuralgia and other intermittent neuralgias respond exceptionally well. In continuous neuropathy, surgical intervention that may create further injury is not advised.

Chemosensory regeneration or the improvement in taste is incomplete following nerve repair. Zuniga et al demonstrated 50% of 12 patients improved after microneurosurgical repair. They also suggested an increase in fungiform papillae and pores over time.[21] Taste is usually compensated for over time, and no known treatment is helpful.

Conclusion

Although quite rare, lingual nerve injury results in a variety of clinical presentations. Many patients have no problem adjusting to the change, but in some, it may be irritating. There does not seem to be any specific change unique to the lingual nerve other than the anatomical locations. Research into the genetic and other susceptibility issues will be enlightening and may provide us with the ability to better prevent these deficits.


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