Clinical insights into traumatic injury of the inferior alveolar and lingual nerves: a comprehensive approach from diagnosis to therapeutic interventions

OBJECTIVES

This scoping review explores the risk and management of traumatic injuries to the inferior alveolar and lingual nerves during mandibular dental procedures. Emphasizing the significance of diagnostic tools, the review amalgamates existing knowledge to offer a comprehensive overview.

MATERIALS AND METHODS

A literature search across PubMed, Embase, and Cochrane Library informed the analysis.

RESULTS

Traumatic injuries often lead to hypo-/anesthesia and neuropathic pain, impacting individuals psychologically and socially. Diagnosis involves thorough anamnesis, clinical-neurological evaluations, and radiographic imaging. Severity varies, allowing for conservative or surgical interventions. Immediate action is recommended for reversible causes, while surgical therapies like decompression, readaptation, or reconstruction yield favorable outcomes. Conservative management, utilizing topical anesthesia, capsaicin, and systemic medications (tricyclic antidepressants, antipsychotics, and serotonin-norepinephrine-reuptake-inhibitors), proves effective for neuropathic pain.

CONCLUSIONS

Traumatic nerve injuries, though common in dental surgery, often go unrecorded. Despite lacking a definitive diagnostic gold standard, a meticulous examination of the injury and subsequent impairments is crucial.

CLINICAL RELEVANCE

Tailoring treatment to each case's characteristics is essential, recognizing the absence of a universal solution. This approach aims to optimize outcomes, restore functionality, and improve the quality of life for affected individuals.

Longitudinal Treatment Outcomes of Microsurgical Treatment of Neurosensory Deficit after Lower Third Molar Surgery: A Prospective Case Series

Objective

To prospectively evaluate the longitudinal subjective and objective outcomes of the microsurgical treatment of lingual nerve (LN) and inferior alveolar nerve (IAN) injury after third molar surgery.

Materials and Methods

A 1-year longitudinal observational study was conducted on patients who received LN or IAN repair after third molar surgery-induced nerve injury. Subjective assessments (“numbness”, “hyperaesthesia”, “pain”, “taste disturbance”, “speech” and “social life impact”) and objective assessments (light touch threshold, two-point discrimination, pain threshold, and taste discrimination) were recorded.

Results

12 patients (10 females) with 10 LN and 2 IAN repairs were recruited. The subjective outcomes at post-operative 12 months for LN and IAN repair were improved. “Pain” and “hyperaesthesia” were most drastically improved. Light touch threshold improved from 44.7g to 1.2g for LN repair and 2g to 0.5g for IAN repair.

Conclusion

Microsurgical treatment of moderate to severe LN injury after lower third molar surgery offered significant subjective and objective sensory improvements. 100% FSR was achieved at post-operative 6 months.

[Clinical application of the combined radical operation without breaking lower lip and mandible for tongue and lingual root carcinoma]

OBJECTIVE

To investigate the clinical applicability and outcomes of the combined radical operation without breaking the lower lip and mandible with one-stage reconstruction using free anterolateral thigh flap for tongue and lingual root carcinoma.

METHODS

The operation with or without breaking lower lip and mandible was performed respectively in 245 patients (experimental group) and 120 patients (control group).

RESULTS

Removal of tumor and neck dissection were conducted successfully in all patients of two groups with no serious postoperative complication. With the follows-up of 6 to 36 months, in the patients of experimental group there was no recurrence for primary sites but 3 cases with neck lymphnode recurrence, the functions of chewing, swallowing and speaking were good, there was no damage to appearance, and no osteoradionecrosis occurred in the lymphnode positive cases after radiotherapy; in the patients of experimental group there was no recurrence for primary sites but 4 cases with neck lymphnode recurrence, the functions of chewing, swallowing and speaking were good, but there was apparent scar in neck and face, and osteoradionecrosis occurred in 11 of lymphnode positive cases.

CONCLUSIONS

The combined radical operation without breaking the lower lip and mandible with one-stage reconstruction using free anterolateral thigh flap is feasible for tongue and lingual root carcinoma (T2-T3), which reduces the risk for osteoradionecrosis in lymphnode positive cases after radiotherapy and keeps good appearance for patients.

Restoration of quinine-stimulated Fos-immunoreactive neurons in the central nucleus of the amygdala and gustatory cortex following reinnervation or cross-reinnervation of the lingual taste nerves in rats

Remarkably, when lingual gustatory nerves are surgically rerouted to inappropriate taste fields in the tongue, some taste functions recover. We previously demonstrated that quinine-stimulated oromotor rejection reflexes and neural activity (assessed by Fos immunoreactivity) in subregions of hindbrain gustatory nuclei were restored if the posterior tongue, which contains receptor cells that respond strongly to bitter compounds, was cross-reinnervated by the chorda tympani nerve. Such functional recovery was not seen if instead, the anterior tongue, where receptor cells are less responsive to bitter compounds, was cross-reinnervated by the glossopharyngeal nerve, even though this nerve typically responds robustly to bitter substances. Thus, recovery depended more on the taste field being reinnervated than on the nerve itself. Here, the distribution of quinine-stimulated Fos-immunoreactive neurons in two taste-associated forebrain areas was examined in these same rats. In the central nucleus of the amygdala (CeA), a rostrocaudal gradient characterized the normal quinine-stimulated Fos response, with the greatest number of labeled cells situated rostrally. Quinine-stimulated neurons were found throughout the gustatory cortex, but a "hot spot" was observed in its anterior-posterior center in subregions approximating the dysgranular/agranular layers. Fos neurons here and in the rostral CeA were highly correlated with quinine-elicited gapes. Denervation of the posterior tongue eliminated, and its reinnervation by either nerve restored, numbers of quinine-stimulated labeled cells in the rostralmost CeA and in the subregion approximating the dysgranular gustatory cortex. These results underscore the remarkable plasticity of the gustatory system and also help clarify the functional anatomy of neural circuits activated by bitter taste stimulation.

Nerve injuries from mandibular third molar removal

Injuries to peripheral branches (IAN, LN, LBN) of the trigeminal nerve during the removal of M3s are known and accepted risks in oral and maxillofacial surgery practice. These risks might be reduced by modifications of evaluation or surgical techniques, depending on the surgeon's judgment in individual patients. If a nerve injury does occur, prompt recognition, subjective and objective evaluation,and development of a treatment plan, if the sensory deficit fails to resolve in a reasonable period and is unacceptable to the patient, give the patient the best chance of achieving improvement or recovery of sensory function in the distribution of the injured nerve. Microneurosurgery may produce return of useful sensory function or complete sensory recovery, if done in a timely fashion by an experienced microsurgeon, in greater than 80% of patients who sustain nerve injuries during the removal of M3s.

Simultaneous pleomorphic adenoma of the left parotid gland and adenoid cystic carcinoma of the contralateral sublingual salivary gland: a case report

INTRODUCTION

Sublingual salivary gland neoplasms are extremely rare, accounting for only 0.3-1% of all epithelial salivary gland tumors. Most of the sublingual tumors are malignant, adenoid cystic carcinoma (ACC) and mucoepidermoid carcinoma (MEC) being the most common histological types. The coexistence of two salivary gland tumors located in different major salivary glands is uncommon.

CASE REPORT

A rare case of two simultaneous tumors of the major salivary glands, one in the sublingual and the other in the contralateral parotid gland in a female patient is reported.

DISCUSSION

The diagnostic procedure followed, and the management of the patient, is outlined in the paper.

Comparison of lingual and inferior alveolar nerve microsurgery outcomes

OBJECTIVE

To evaluate the outcomes of published studies involving lingual nerve (LN) and inferior alveolar nerve (IAN) microsurgery and reviewing differences in sensory recovery and timing to repair for both groups.

METHOD AND MATERIALS

A total of 29 patient charts referred to the principal investigator were reviewed (15 IAN and 14 LN). Age, gender, mechanism of injury, and time from injury to surgical repair were assessed. Two-point discrimination and tactile detection threshold (via von Frey monofilaments) were the utilized measured variables because both are quantifiable and repeatable data points.

RESULTS

There was a predominance of female patients (10 IAN, 12 LN), and the mean age of the patients in the IAN group (37.40 +/- 9.61 years) was significantly higher than in the LN group (28.86 +/- 7.99 years). The time from injury to microsurgery was longer in the LN group (234.10 +/- 166.13 days) than the IAN group (137.80 +/- 83.80 days). Four patients from the IAN group and 7 from the LN group were operated on more than 6 months after the injury. Of the 15 patients who underwent IAN microsurgery, 1 patient had no change in either von Frey or 2-point discrimination results after the procedure, and 2 patients had no changes in only von Frey results. For the 14 patients undergoing LN repair, 1 patient demonstrated no change in the 2-point discrimination test and 1 patient had a reduced postoperative von Frey result compared to the preoperative measurement.

CONCLUSION

Patients undergoing LN and IAN microsurgery benefit from trigeminal nerve microsurgery. No statistically significant differences overall were observed when comparing the outcomes of LN and IAN microsurgery. Patients undergoing trigeminal nerve microsurgery for LN and IAN injuries 6 months after injury derived less sensory recovery; however, significant improvement was still observed, warranting consideration for microsurgery in those patients who might present later for initial surgical consultation.

Effect of lingual and hypoglossal nerve reconstruction on swallowing function in head and neck surgery: prospective functional outcomes study

OBJECTIVES

To examine the effect on oral swallowing function of reanastomosis of lingual and hypoglossal nerves divided and reconstructed during head and neck cancer surgery and to determine the importance (if any) of sensory reconstruction in oral cavity cancer surgery.

STUDY DESIGN

Prospective cohort study.

METHODS

Forty-four patients underwent resection and free tissue reconstruction of oropharyngeal squamous cell carcinoma between January 1999 and September 2006. Postoperative lingual and hypoglossal nerve status was recorded. All patients were scheduled to undergo videofluoroscopic swallowing studies (VFSSs) pre- and 12 months postoperatively. The oral residue score, bolus oral transit time, and aspiration score were recorded for all patients completing the assessments.

RESULTS

The oral transit time and oral residue score increased in patients with both lingual and hypoglossal nerves resected. Oral swallowing efficiency was preserved if one or both of the lingual and hypoglossal nerves were preserved or reconstructed following cancer resection. Ninety-one percent of patients swallowed safely at 12 months postoperatively.

CONCLUSIONS

Loss of both the lingual (sensory) and hypoglossal (motor) supply of parts of the oral cavity has a detrimental effect on oral swallowing. If either the sensory or the motor supply to these regions can be preserved or reconstructed, oral swallowing efficiency can be maintained. During oral cancer extirpation, removal of muscular structures often negates possible motor reconstruction. This increases the need for sensate reconstruction of oral cavity defects via primary reanastomosis of nerves or sensate free tissue transfer to preserve oral swallowing efficiency.

Does Early Repair of Lingual Nerve Injuries Improve Functional Sensory Recovery?

PURPOSE

This study evaluated the relationship between timing of lingual nerve repair and functional sensory recovery.

MATERIALS AND METHODS

Using a retrospective cohort study design, the investigators enrolled a sample of subjects who had lingual nerve repair. The predictor variable was time between injury and repair, categorized as early (<90 days after injury) or late (>90 days after injury). The outcome variable was the time to functional sensory recovery (FSR), measured in days. Other variables were categorized as demographic, anatomic, and operative. Uni- and multivariate Cox proportional hazards models were used to evaluate the association between the timing of the repair and time to FSR.

RESULTS

The study sample was composed of 64 subjects who had lingual nerve repair between January 1998 and January 2005. The mean time between injury and repair was 153.2 (31-1606) days; 21.9% of subjects had early repair. The mean age was 28.4 +/- 8.0 years, 62.5% of subjects were female; 77% of the injured nerves were repaired by direct suture, and 23% had surgical exploration with decompression/neurolysis. In bivariate analyses, early repair, method of repair, and neuroma were statistically or near-statistically associated with time to FSR (P <or= .12). In a multiple Cox proportional hazards model, early repair was associated with time to FSR (P = .02). Ninety-three percent of subjects in the early repair group achieved FSR within 1 year, compared with 62.9% in the late group (P = .05).

CONCLUSIONS

Early repair of lingual nerve injuries results in FSR more frequently and earlier than late repair.

Submandibular Gland Excision: 15 Years of Experience

PURPOSE

The surgical management of submandibular gland diseases has always been a challenge because it carries a considerable risk of nerve injury. The aim of this study was to review a single institution's experience of a nonselected case series of submandibular gland excision over 15 years.

MATERIALS AND METHODS

We retrospectively analyzed 258 unselected submandibular excisions of a tertiary university center for the histopathologic diagnosis and postoperative morbidity; 119 patients (46%) with sialolithiasis, 88 patients (34%) with sialadenitis, and 51 patients (20%) with submandibular tumors were operated.

RESULTS

We found a high rate of malignant tumors (42%) in the group of submandibular gland tumors. A low rate of transient palsies of the mandibular branch of the facial nerve (9%) and lingual nerve (2%) was observed. One patient developed a permanent paresis of the mandibular branch (<1%).

CONCLUSION

Our large series has shown that standardized submandibular sialadenectomy is a safe operation with a low rate of complications. Malignant disease is frequent in tumors of the submandibular gland.

Functional role of lingual nerve in breastfeeding

Functional role of lingual nerve in breastfeeding was investigated in rat pups during the suckling period. DiI, a postmortem neuronal tracer, was used to confirm the immature lingual nerve (LN) responsible for tongue sensation and resulted in successful fiber labeling anterogradely to the tongue, which showed different distribution patterns from fiber labeling derived from the hypoglossal nerve. Unilaterally LN-injured pups did not show suckling disturbance with absence of any shortening (P11 pups: 559+/-16s; 105% of the control value) in nipple attachment time and the survival rate remained high (P11: 100%). Bilaterally LN-injured pups showed suckling disturbance with marked shortening (P11 pups: 220+/-54 s; 42% of the control value) in nipple attachment time and a low survival rate (P1: 33%; P11: 41%). Bilaterally infraorbital nerve-injured or bilaterally bulbectomized pups did not show any nipple attachment at all and there were no survivors, confirming the crucial roles of upper lip sensation and olfaction in suckling. Based on these findings, we conclude that tongue sensation is very important, but not essential for suckling.

Functional Sensory Recovery After Trigeminal Nerve Repair

PURPOSE

The aim of this study was to estimate the proportion of subjects who achieved functional sensory recovery (FSR) 1 year after inferior alveolar or lingual nerve repair and to identify risk factors associated with failure to achieve FSR.

METHODS

Using a retrospective cohort study design, we developed a sample composed of subjects who underwent lingual or inferior alveolar nerve repair. Eligible subjects had at least 1 postoperative visit. For subjects having bilateral nerve repair, 1 side was selected randomly for analysis. Predictor variables were categorized as demographic, anatomic, and operative. The outcome variable was the time to FSR, measured in days. Kaplan-Meier survival methods were used to estimate the proportion of subjects with FSR at 1 year. Uni- and multivariate Cox proportional hazard models were used to identify risk factors for the failure to reach FSR at 1 year.

RESULTS

The study sample was composed of 60 subjects with a mean age of 28.7 +/- 8.3 years; 68.3% were female. The majority (86.7%) of subjects presented with a preoperative chief complaint of altered sensation and had lingual nerve damage (93.3%) that was repaired by direct suturing (75%). The mean interval between injury and repair was 145.9 +/- 200.0 days. At 1 year postoperatively, 75% of the subjects had achieved FSR (95% confidence interval [CI]: 64% to 86%).

CONCLUSIONS

The majority of subjects undergoing trigeminal (V(3)) nerve repair achieved functional sensory recovery within 1 year of surgical repair. Patients with evidence of neuroma formation were less likely to achieve FSR at 1 year in a multivariate model.

Lésions du nerf lingual lors de l’extraction d’une dent de sagesse inférieure

INTRODUCTION

Lingual nerve injury is one of the most important complications after removal of a lower third molar.

CASE REPORT

We report two cases of this complication in our experience. In the first case, lingual nerve injury was repaired immediately and the patient recovered total tongue sensitivity. In the second case, lingual nerve exploration was not undertaken and the patient developed complete tongue anesthesia.

DISCUSSION

Opinions are quite different about the delay before exploration of an injured lingual nerve. However, absence of sensory improvement incited us to undertake surgical exploration of the nerve. Due to the degenerative lesion of the damaged nerve, timing of repair before three months seems preferable. In young patients, early repair, and good quality nerve suture without tissue loss improve sensitive recovery of the tongue.

A Comparison of Patient Satisfaction and Objective Assessment of Neurosensory Function After Trigeminal Nerve Repair

PURPOSE

The purpose of this study was to compare objective and subjective assessments of neurosensory function after trigeminal nerve repair.

METHODS

This was a retrospective cohort study using a sample of patients who underwent surgical repair of trigeminal nerve injuries. The primary study variables were categorized as objective or subjective. The objective variable was the change in neurosensory examination between preoperative and 1-year postoperative visits. Neurosensory status was measured using an ordinal scale ranging from anesthetic (0) to normal (4). Subjective variables included patient satisfaction with the nerve repair and patient assessment of injury-related oral dysfunction. Demographic, anatomic, and operative variables were also collected. Appropriate univariate and bivariate statistics were computed.

RESULTS

The sample was composed of 19 patients (14 female, 17 Caucasian) who had trigeminal nerve repair (17 lingual, 2 inferior alveolar). The mean duration between injury and repair was 4.5 +/- 2.3 months; between repair and postoperative assessment was 11.9 +/- 0.9 months. The mean change in neurosensory status was 1.3 +/- 1.0 levels. The majority of patients (63.1%) rated their satisfaction with the outcome of treatment as "good" to "excellent." There was a statistically significant correlation between change in neurosensory status and patient satisfaction (rho = 0.86; P < .01).

CONCLUSION

There is evidence of a strong correlation between improvement in the neurosensory examination following trigeminal nerve repair and patient satisfaction with the surgical outcome 1-year postoperatively. Patients who experience greater neurosensory improvement also report lower frequencies of related oral dysfunction.

Long-Term Outcome Assessment for Lingual Nerve Microsurgery

OBJECTIVE

A retrospective study was undertaken to investigate the clinical outcomes resulting from the microsurgical repair of lingual nerve injuries. The study was based on patient chart review.

PATIENTS AND METHODS

A total of 20 patients referred to the principal investigator (V.B.Z.), with a diagnosis of lingual nerve injury who underwent trigeminal nerve microsurgery during a 3-year period (1999 to 2002), were entered in this study. All patients received a complete history and physical examination, and thorough preoperative and postoperative neurosensory testing to evaluate clinical response to hot, cold, cotton wisp, vibration, 2-point discrimination, directional stroke, and fine touch as determined by Von-Frey filaments.

RESULTS

All patients underwent an external neurolysis procedure in combination with an internal neurolysis, neuroma excision, or primary neurorrhaphy under microscopic guidance depending on the intraoperative findings. The average time from injury to surgery was 8 months. The patients were followed for an average of 9 months after surgery, and assessment was based on the patients subjective experience as well as standardized neurosensory testing. Eighteen patients (90%) had some improvement in neurosensory function and 2 patients (10%) reported no improvement. One of the patients exhibiting no clinical improvement had a prolonged delay in seeking treatment, and the distal nerve could not be localized intraoperatively. Most patients were operated on between 2.5 and 7 months after injury, and there was no statistical difference in outcome as a function of the time from injury to repair in this group of patients. This subgroup of responding patients averaged at least 50% improvement in neurosensory function.

CONCLUSION

Microsurgical repair of lingual nerves provides moderate to significant improvements in clinical sensory function and is a useful option in treating affected individuals, especially when implemented soon after injury.

Subjective Outcomes Following Sural Nerve Harvest

PURPOSE

The goal of this study was to assess subjective patient recovery of donor site sensory deficit following sural nerve harvest for trigeminal nerve repair surgery.

PATIENTS AND METHODS

A review of 42 consecutive sural nerve graft patient records yielded 26 patients, at least 20 months following sural nerve grafting for trigeminal nerve repair, who participated in a telephone questionnaire survey to assess subjective outcomes. The association between donor site outcome and other factors, including nerve graft recovery, age, gender, pain, cold sensitivity, scar cosmesis and tactile sensitivity, and legal involvement were analyzed, and presurgical and present levels of donor and nerve graft site sensibility were compared.

RESULTS

The perceived area of donor site sensory deficit decreased significantly over time. Postoperative donor site pain and cold sensitivity at low levels were reported by few patients, and the majority have completely resolved. Most patients reported no problems with scar cosmesis or pain. There was a moderate agreement between donor site recovery and nerve graft recovery (kappa = 0.32). Few patients reported satisfaction with one site and not the other or complete dissatisfaction with both sites. Other factors such as age, gender, or legal involvement were not found to correlate with satisfaction level.

CONCLUSIONS

The use of a questionnaire for subjective assessment of neurosensory recovery following nerve graft repair yields outcomes information that is generally not considered in the traditional clinical patient assessment. The majority of patients tolerate sural nerve harvest without significant donor site morbidity.

Preganglionic parasympathectomy decreases salivary SIgA secretion rates from the rat submandibular gland

Immunoglobulin A (IgA) is transported into saliva by salivary cells expressing the polymeric immunoglobulin receptor (pIgR). In rat salivary glands, autonomic nerves stimulate this process. To examine how nerves affect pIgR-mediated IgA secretion, the chorda-lingual nerve was sectioned. One week after preganglionic parasympathectomy, both the stimulated and unstimulated rates of salivary IgA secretion were reduced, despite similar glandular amounts of IgA. Biochemical analysis of cells from parasympathectomised and control glands indicated reduced membrane expression of pIgR. It appears the removal of long-term parasympathetic input has affected the routing of pIgR within salivary cells and reduced the SIgA transport into saliva.

Ultrastructural characteristics of axons in traumatic neuromas of the human lingual nerve

AIMS

To determine the ultrastructural characteristics of axons in traumatic neuromas of the human lingual nerve during the surgical removal of lower third molar teeth and to establish whether any characteristics were different between patients with dysesthesia and patients without dysesthesia.

METHODS

Transmission electron microscopy was used to determine the ultrastructural morphological characteristics of human lingual nerve neuromas (n = 34) removed at the time of microsurgical nerve repair. From a sample population of myelinated and nonmyelinated fibers within the neuromas, fiber diameter, myelin thickness, g-ratio, and the number of mitochondria per axon were quantified. Comparisons were made with normal control lingual nerve specimens (n = 8) removed at the time of organ donor retrieval.

RESULTS

Significant differences in ultrastructural morphology were found between the neuromas and control nerves. The neuromas contained a higher proportion of small (2- to 8-microm diameter) myelinated nerve fibers than controls, and the mean myelinated fiber diameter was significantly lower in neuromas than in controls. Mean myelin sheath thickness was significantly thinner in neuromas (0.6 +/- 0.1 microm) than in controls. However, the g-ratio, which is a measure of the myelination status of the nerve fibers in relation to their diameter, was found to be similar in each group, suggesting a normal process of myelination in the damaged axons. Nonmyelinated axon diameter was also significantly smaller in the neuromas than in the controls, and Schwann cells were found to sheathe more nonmyelinated axons in neuromas than in controls. The ratio of nonmyelinated to myelinated axons was significantly higher in neuromas than in controls. However, no significant differences were found between patients with dysesthesia and those without dysesthesia.

CONCLUSION

Damage to the lingual nerve results in marked changes to axon diameter, myelin sheath thickness, and Schwann cell-axon relationships. These ultrastructural changes could contribute to the altered electrophysiological properties of axons trapped within neuromas. However, no significant differences in the ultrastructural characteristics studied were found between specimens from patients with or without symptoms of dysesthesia.

[Experimental study of the fungiform papilla and taste bud regeneration following microsurgical repair of lingual nerve in rat]

PURPOSE

To investigate the changes of taste buds following injury to lingual nerve and the regeneration of the fungiform papillae and taste buds following microsurgical epineurial anastomosis of transecting injured lingual nerves in rats.

METHODS

We observed the numbers and shapes of the fungiform papillae and taste buds with stereomicroscope, light microscope, and scanning electron microscope at 20 and 100 days after the clamp injury to lingual nerve, or the transecting injury to lingual nerve with/without immediate microsurgical epineurial anastomosis of the injured lingual nerve in rats.

RESULTS

The fungiform papillae and taste buds degenerated, atrophied and their numbers diminished obviously at 20 days following either the clamp injury or transecting injury to the lingual nerve. The fungiform papillae and taste buds didn't regenerate spontaneously at 100 days following transection of the lingual nerve without microsurgery. The degenerated fungiform papillae and taste buds regenerated and recovered completely at 100 days following both clamp injury to the lingual nerve and transection of the lingual nerve with immediate microsurgical epineurial anastomosis.

CONCLUSION

The degenerated fungiform papillae and taste buds have good ability to regenerate spontaneously following clamp injury to the lingual nerve; the degenerated fungiform papillae and taste buds can regenerate completely with immediate microsurgical epineurial anastomosis of the transected lingual nerve. The quantity and morphology of fungiform papillae and taste buds can be used as objective indicators in the function rehabilitation of injured lingual nerve.

An electrophysiological study into the effect of neurotrophin-3 on functional recovery after lingual nerve repair

OBJECTIVE

Neurotrophin-3 (NT-3) is known to ameliorate central changes that result from peripheral nerve injury and may promote regeneration of myelinated axons. We have assessed its role in the functional recovery of sensory afferents and autonomic efferents after repair of the chorda tympani and lingual nerves in the cat.

DESIGN

Six months after entubulation repair, with or without the incorporation of NT-3 at the repair site, the recovery of secretomotor and vasomotor efferents was determined by recording salivary flow from the submandibular gland and temperature changes on the tongue surface, each evoked by stimulation of the repaired nerve. Electrophysiological recordings from the lingual and chorda tympani nerves proximal to the repair allowed characterisation of mechanosensitive, thermosensitive and gustatory afferents.

RESULTS

When compared with data from uninjured control animals, both repair groups showed persistent reductions in conduction velocity, receptor sensitivity, spontaneous discharge, proportion of gustatory and thermosensitive units, and rate of salivary secretion. Comparisons between the two repair groups revealed that in the NT-3 group, salivary secretion rate was lower and the activity evoked in the chorda tympani by gustatory or thermal stimuli was lower, but the spontaneous discharge rate was higher. Mechanosensitive units in the lingual nerve had slower conduction velocities but the mechanoreceptive field size, adaptation time and discharge frequency had increased.

CONCLUSIONS

Despite its known trophic role in the lingual somatosensory system, NT-3 did not enhance functional recovery from injury and had a negative effect on the long-term outcome for sensory and autonomic fibres.

Intraoral sensation before and after radiotherapy and surgery for oral and pharyngeal cancer

BACKGROUND

Patients with unilateral oral or pharyngeal cancer often receive bilateral radiotherapy because of the potential for metastases. Because postoperative sequelae are evident on the tumor side, to date little attention has been paid to sensory alterations after radiotherapy on the healthy, nontumor side. The objective of this study was to investigate possible sensory alterations.

METHODS

Intraoral sensation was tested bilaterally at standardized sites in 27 patients and 20 controls. Preoperative radiotherapy was bilateral in 19 patients and unilateral in eight patients. Patients were tested before treatment, after radiotherapy, and after surgery at 6 months and 1 year. Comparisons were performed interindividually and intraindividually and between groups.

RESULTS

A delayed deterioration of sensation was revealed on the nontumor side 6 months after radiotherapy. There was no recovery 1 year after treatment.

CONCLUSIONS

Intraoral sensation cannot be evaluated directly after radiotherapy. It is plausible that sensory deterioration after radiotherapy has an impact on functional rehabilitation after tumor treatment.

Current management of damage to the inferior alveolar and lingual nerves as a result of removal of third molars

In this review we present algorithms to guide the clinical management of patients who sustain damage to the inferior alveolar or lingual nerves during the removal of lower third molars. Monitoring recovery using simple sensory testing allows those patients who may benefit from some form of intervention to be identified. There is good evidence that some surgical procedures produce worthwhile improvements in sensation but management of nerve injury-induced dysaesthesia remains problematic.

[Nerve injury following implant placement: prevention, diagnosis and treatment modalities]

Nerve injury is a well-known complication following oral and maxillofacial surgery. Direct trauma, inflammation and infection are postoperative neural disturbances main causes. The most inflicted nerves associated with endosseous implant placement are those innervating the mandible: the inferior alveolar nerve, the mental nerve and the lingual nerve. Evaluation of the nerve injury characteristics and severity as early as possible has always imposed a great challenge for clinicians. We demonstrate a reliable yet simple way of dealing with this kind of problem in conjunction with comparing preoperative and postoperative sensation of the chin, the tongue and the lower lip. On the other hand, it is considerably important to take preventive measures for such injuries by using appropriate radiographic images. If a nerve damage has occurred, best prognosis is to be expected by early and appropriate treatment. It is imperative to treat such injuries in four months following the injury, otherwise a permanent nerve damage may occur. Further investigation of nerve damage risks following implant placement should be performed in order to enable patient to decide whether having implants dependent rehabilitation or choosing an alternative.

Patient satisfaction after trigeminal nerve repair

OBJECTIVE

The purpose of this study was to measure patient satisfaction and to evaluate the factors influencing patients' perceptions of the outcome of inferior alveolar nerve or lingual nerve repair.

STUDY DESIGN

We used a retrospective cohort study design and a sample of patients who underwent repair of inferior alveolar nerve or lingual nerve injuries. The major outcome variable was the patient's overall satisfaction with treatment. The patient's satisfaction was rated as either good to excellent (group A) or fair to poor (group B).

RESULTS

The study sample was composed of 46 patients with a mean age of 28 +/- 12 years; 76% were female. Fifty-five percent of the sample reported their overall satisfaction to be good to excellent. No individual predictor factors were statistically associated with patient satisfaction. Among the outcome variables, the measures of taste, pronunciation, self-consciousness, and function were statistically significantly different (P <.05) between the 2 groups.

CONCLUSIONS

After nerve repair, more than half of the patients rated their overall satisfaction with the operative results to be good to excellent.

Management of patients with trigeminal nerve injuries after mandibular implant placement

BACKGROUND

Placement of mandibular endosseous implants can result in damage to the lingual nerve, the inferior alveolar nerve or both nerves. All dentists who place mandibular implants should be aware of the appropriate early management of these injuries, as well as the appropriate time to refer patients with these injuries to a microneurosurgeon.

OVERVIEW

The lingual nerve is less likely to undergo spontaneous regeneration than is the inferior alveolar nerve, which is protected within the inferior alveolar canal. Since the inferior alveolar canal can be seen on most panoramic radiographs and on all high-quality computed tomographic scans, it is easier to avoid damage to the inferior nerve than to the lingual nerve, which is not visualized on radiographs and whose relationship to the posterior portion of the mandible varies from person to person.

RESULTS

The authors reviewed one study that showed that lingual nerve repair helped 90 percent of patients. A second study found that patients who underwent lingual nerve repair reported a mean score of 7 on a scale from 0 to 10 in regard to the postoperative return of nerve function. Several other studies reported favorable patient responses to inferior alveolar nerve repair.

CONCLUSIONS AND CLINICAL IMPLICATIONS

These results reinforce the need for early referral and intervention when inferior alveolar nerve injuries occur. Failure to refer patients with trigeminal nerve injury before distal nerve degeneration develops prevents minimization of the injury through microneurosurgical repair.

The results of microneurosurgery of the inferior alveolar and lingual nerve

PURPOSE

The goal was to evaluate the experience of one surgical unit during a 5-year period in the evaluation and management of patients with injuries of the inferior alveolar and lingual nerve with particular reference to indications for and results of microneurosurgery.

PATIENTS AND METHODS

This study includes all patients referred with a diagnosis of injury to the inferior alveolar or lingual nerve during 5-year period from January 1, 1994, to January 1, 1999. All patients were evaluated with Frey's hairs for touch and direction sense, 2-point discrimination, and hot and cold water and Minnesota thermal discs for temperature sensation. Patients who fulfilled certain specified criteria were offered microneurosurgery, and the results were evaluated for those who underwent microneurosurgery.

RESULTS

The study consisted of 880 consecutive patients; 96 were thought to fulfill the criteria for microneurosurgery. Of these, 51 underwent microneurosurgical exploration and repair. In 5 patients, no injury could be detected at surgery, and no corrective surgery was performed other than decompression. In 26 patients, excision and direct anastomosis were performed, and in an additional 20 patients, nerve gap reconstruction was performed. In 16 of these 20 patients, reconstruction was performed with an autogenous vein graft, and in 2 patients, a Gore-Tex tube graft (W.L. Gore & Associates, Inc, Flagstaff, AZ) was used to bridge the nerve gap. In 2 patients, an autogenous nerve was used. Thirty-four of the repairs were made on the lingual nerve, and 17 were made on the inferior alveolar nerve. With the use of established criteria, 10 patients were considered to have had a good improvement in sensation, 18 patients were considered to have had some improvement in sensation, and 22 patients were considered to have had no improvement in sensation; 1 patient reported an increase in dysesthesia after surgery. The semiobjective assessment of patients did not always correspond with the patients' subjective evaluation.

CONCLUSION

In a relatively small study in selected cases, microneurosurgery can provide a reasonable result in improving sensation in the inferior alveolar and lingual nerve. More than 50% of patients experienced some improvement in sensation, and dysesthesia did not develop after surgery in any patient who did not have it before surgery.

External neurolysis of the lingual nerve

The lingual nerve is sometimes injured during the surgical removal of an impacted mandibular third molar. The level of sensory recovery was studied in 10 patients who underwent external neurolysis of the lingual nerve. The mean time from third molar surgery to neurolysis was 13.5 months (range 9-24 months). Seven of the 10 patients showed significant improvement, three patients regaining normal sensation. Three patients showed no improvement. These results show that external neurolysis should be considered for patients with altered sensation in the distribution of the lingual nerve.

Surgical management of lingual nerve injuries

Injuries to the lingual nerve remain a relatively uncommon event. However, given the frequency of surgical procedures in this anatomic region, it is likely that every oral and maxillofacial surgeon will be required to manage such an injury. When spontaneous recovery of lingual sensation is absent, microsurgical reconstruction can predictably achieve improved sensation in a majority of patients provided that such injuries are properly assessed and treated early. The quality of the sensory improvement is related to the age of the patient, the timing of surgery, the extent of the neural injury, and the quality of the repair.

Surgical management of trigeminal neuropathic pain

Surgical treatment of mechanical trigeminal nerve injuries resulting in neuropathic pain varies with the type of injury (i.e., amputation or compression), presence of painful neuromas, and adjacent hard/soft tissues. Microsurgical principles that include access, preparation, and repair of the various nerve injuries are recommended for surgical treatment. The choice of surgical repair depends on the microscopic pathology and the presence or absence of adequate distal nerve tissue.

The use of autogenous vein grafts for inferior alveolar and lingual nerve reconstruction

PURPOSE

This study evaluated whether an autogenous vein graft forms a satisfactory conduit for nerve regeneration.

PATIENTS AND METHODS

Fifteen patients received a total of 16 autogenous vein grafts to repair continuity defects of the inferior alveolar (6) and lingual nerves (10) nerves. All were treated between 4 and 10 months after injury. At surgery, the postresection defects ranged from 2 to 14 mm. All lingual nerves were repaired with saphenous vein grafts from an intraoral approach and all inferior alveolar nerves were repaired with facial vein grafts inserted from an extraoral approach.

RESULTS

Lingual nerve repair in 3 cases where the gap between the nerve ends was 5 mm or less resulted in some return of sensation. In 7 cases where the gap was between 5 and 14 mm, there was no return of sensation. In the 6 inferior alveolar nerve repairs there was some return of sensation in all cases and there was good return of sensation in 3 cases. One patient redeveloped dysesthesia in the inferior alveolar nerve and subsequently had a neurectomy. Histologic material was available from this case.

CONCLUSIONS

It appears that a vein graft can form a physiologic conduit for nerve regeneration. The results are more successful with shorter gaps, which indicates that, in some respects, the vein acts like a barrier membrane. The increased success rate in the inferior alveolar nerve repair may be because the vein remains straight and patent in the inferior alveolar canal. The lack of success with a long lingual nerve gap repair may be because the vein is collapsed or kinked by movement of the tongue, which may inhibit neural regeneration. Therefore, vein grafts should not be used for long lingual nerve continuity defects.

Use of Gore-Tex tubing as a conduit for inferior alveolar and lingual nerve repair: experience with 6 cases

PURPOSE

This report evaluates treatment outcomes associated with the use of Gore-Tex (GT; W.L. Gore & Associates, Flagstaff, AZ) vein graft tubing as a conduit for repair of inferior alveolar nerve (IAN) and lingual nerve (LN) continuity defects.

PATIENTS AND METHODS

Six patients (5 female and 1 male) with painful dysesthesia secondary to injuries of the IAN (n = 3) or LN (n = 3) underwent surgical exploration and resection of pathologic tissue. Reconstruction of the resultant continuity defects was performed using 3-mm diameter GT tubing sutured to the epineurium of the proximal and distal nerve trunks. Nerve reconstruction was performed an average of 20 months after injury (range, 4 to 48 months). Patients were tested before and after surgery with the following tests: subjective pain level using an analogue scale, sharp stimulus, touch, cold sensation, directional sense, and 2-point discrimination.

RESULTS

Four patients reported no change in subjective pain level, and 2 patients had minimal decrease in pain. Two patients reported some sensation to sharp stimulus, and 1 patient was hypersensitive. Three patients responded to touch, and 3 had no response. Four patients had no response to cold sensation, and 2 had a delayed response. Only 1 patient could detect brushstroke direction. Three patients had no response to 2-point discrimination, and 3 responded at greater than 20 mm.

CONCLUSIONS

Use of GT tubing in this group of patients produced poor clinical outcomes and is not recommended for nerve reconstruction of IAN and LN continuity defects.

Soft tissue surgery in the oral and maxillofacial region

The practice of dentistry is most often perceived as the treatment of the hard tissues of the oral region, specifically the teeth and jaws. However, there are many disorders and conditions involving surgical treatment of the soft tissues that extend to the adjacent and associated structures of the oral and maxillofacial surgery region.

A prospective, quantitative study on the clinical outcome of lingual nerve repair

We previously showed in laboratory studies that the most effective method for repair of damaged lingual nerves was by excision of the neuroma, mobilization of the stumps, and direct reapposition with epineurial sutures. We have now undertaken a prospective study in a series of 53 patients treated by this method and have evaluated the outcome by quantifying and comparing the results of tests of sensation before and after operation. The outcome in individual patients was variable. However, pooled data from all patients showed a highly significant improvement in sensation at the final assessment 12 months or more after the repair. The proportion of patients who responded to most or all light touch stimuli increased from 0% to 51% after repair, and the proportion who responded to pin-prick stimuli increased from 34% to 77%. There was no correlation between the final results of any of the tests and the delay before repair. None of the patients regained completely normal sensation and there was no reduction in the number with spontaneous paraesthesia or pain. However, fewer patients tended to bite the tongue by accident and most of them considered the operation worthwhile. These data show that lingual nerve repair is effective in most patients and we suggest that it should be offered to all those who show few signs of spontaneous recovery after injury.

Predominant role of the chorda tympani nerve in the maintenance of the taste pores: the influence of gustatory denervation in ear surgery

The effect on the taste pores of denervation of the chorda tympani nerve in the middle-ear cavity was studied comparing confocal laser microscopy with lingual nerve resection. Taste pore cells were stained for actin with rhodamine-phalloidin and positive fluorescence was observed as a ring shape at the transverse cross sections. Within three days after chorda tympani nerve resection the ring reaction disappeared, although the pore morphology remained intact as seen by scanning electron microscopy. On the other hand, lingual nerve resection did not induce such rapid disappearance of the ring reaction. These results suggest that the chorda tympani nerve plays a predominant role in the maintenance of actin filaments in taste pore cells.

Comparative study on sensory recovery after oral cavity reconstruction by free flaps: preliminary results

Anatomical restoration was once the only goal of reconstructive surgery, but now it represents only one step in the complete functional recovery process to allow resumption of physiological activity. Soft tissue and nerves play important roles in functional recovery, but the potential of these structures is not yet well known. Rehabilitation after oral cavity reconstruction by free flaps needs an interdisciplinary diagnostic and therapeutic approach, in which neurosensory recovery of transferred tissue is an important aspect. Previous studies have used clinical assessment to evaluate sensory recovery after oral reconstruction with free flaps, but these results have been subjective and not quantifiable. The aim of the present study is to evaluate the sensory recovery using objective and standardized electrophysiological data by recording the masseter inhibitory reflexes (MIR) following mental and lingual electrical stimulation. A group of 14 patients who underwent oral cavity reconstruction by transplantation of either forearm (9) or jejunal (5) noninnervated free flaps were investigated. We found that sensory recovery of fasciocutaneous radial forearm free flaps was better than that of jejunal free flaps. This could represent the starting point for further studies about sensory recovery of reconstructed anatomical structures based on standardized and objective electrophysiological data.

Taste perception after lingual nerve repair

PURPOSE

This retrospective study evaluates patients' perception of taste after lingual nerve injury and repair. It is hypothesized that return of taste is a distinct neurophysiologic phenomenon related to specialized taste physiology and it does not correlate with specific, objective sensory return.

PATIENTS AND METHODS

During 1995 to 1996, 30 patients underwent microsurgical repair of lingual nerve injuries. Of these, 22 patients met the inclusion criteria for this study. Chart review documented the date and cause of injury, sensory examination, injury classification, procedures, operative findings, and postoperative sensory examination. A telephone questionnaire addressed whole mouth taste perception with normal daily eating. The questions asked were: 1) Was your sense of taste changed or abnormal after your nerve injury? and 2) Did your sense of taste recover after nerve repair?

RESULTS

All patients had a postinjury, prerepair sensory deficit on levels A, B, and C testing: neurotmesis (n = 14); and axonotmesis (n = 8). The mean time from injury to repair was 16 weeks (range, 3 to 41 weeks). Operative findings confirmed 12 Sunderland Class IV (partial transection) injuries and 10 Class V (complete transection) injuries. All patients had primary microsurgical repair without a nerve graft or entubulization. Postoperatively, 18 patients showed marked improvement in sensory testing at levels A, B and C, and 4 patients showed no significant change. A telephone interview regarding whole mouth taste perception indicated that 20 of 22 patients perceived changed, abnormal taste postinjury and pre-repair. Two patients reported normal taste perception. Postrepair, only 7 of 20 patients reported an increase or return of taste perception to a more normal level. The mean follow-up time was 80 weeks.

CONCLUSION

Most patients (20 of 22) with lingual nerve injuries in this study perceived whole mouth taste as abnormal. After nerve repair, although 82% (18 of 22) of patients had improvement in somatosensory function, whole mouth taste was perceived as improved by only 35% (7 of 20). It is proposed that the perception of whole mouth taste may not be related to the ability to perceive multiple sensory modalities, but rather to special sensory (taste) modality perception. Also, central changes may occur in the special sensory fibers that impact on the brainstem nucleus for taste (nucleus solitarius) and therefore the patient's perception of taste.

Microneurovascular allotransplantation of the canine tongue

INTRODUCTION

Reconstruction of the tongue with existing methods of tissue transfer often leaves glossectomy patients with significant deficits in speech and swallowing. The critical role of the tongue is implied by its unique structure and function. This paper reports the development of an animal model of hemitongue allotransplantation and documents functional and anatomic outcomes of this procedure.

METHODS

Ten pairs of unmatched dogs underwent reciprocal exchange of the left hemitongue with microneurovascular replantation. The unoperated hemitongue acted as the control. Under cyclosporine immunosuppression, animals surviving long term underwent clinical observation, before electromyography, force transduction studies, and histological evaluation being euthanized.

RESULTS

Five animals survived between 6 and 13 months for long-term evaluation. The remaining group were euthanized because of or died of overwhelming infection or uncontrollable transplant rejection. The latter sometimes resulted from difficulty in the delivery of the cyclosporine. Clinical recovery of tongue function was observed, as well as resumption of motor unit potential activity on electromyography. Contractile force recovery of the transplanted tongue averaged 68% of control (range, 47%-97%), and histological study of the hypoglossal and lingual nerves demonstrated anatomic evidence of reinnervation. Preservation of muscle, mucosal, and stromal ultrastructure was seen with light microscopy of the transplanted tongue.

CONCLUSIONS

Allotransplantation of the hemitongue and associated neurovascular apparatus is possible in a large mammalian model, with long-term survival of tissue being accompanied by partial recovery of contractile properties. Anatomical and clinical evidence also points to sensory recovery. These data support the future possibility of employing a similar technique in glossectomy patients.

Effects of reducing submandibular blood flow on secretory responses to parasympathetic stimulation in anaesthetized cats

Submandibular secretory responses to stimulation of the parasympathetic chorda-lingual nerve were investigated in five anaesthetized cats before, during and after withdrawal of blood (ca 20 ml kg-1) in order to investigate the consequences of a reduced blood flow through the gland. Stimulation at different frequencies (2, 4, 6 and 8 Hz) evoked a frequency-dependent increase in the flow of submandibular saliva, sodium concentration, electrolyte and protein output. When the blood pressure was reduced (by about 50%) there was a significant reduction in submandibular blood flow and the secretion of both saliva and protein during stimulation. Under each set of conditions the flow of saliva was linearly related to the blood flow through the gland. It is concluded that submandibular secretory responses to electrical stimulation of the parasympathetic innervation can be significantly attenuated when the blood flow through the gland is reduced under the conditions employed in this study.

Gore-Tex tubing as a conduit for repair of lingual and inferior alveolar nerve continuity defects: a preliminary report

PURPOSE

This report describes the results of using a Gore-Tex (Gore Company, Flagstaff, AZ) tube as a conduit for repair of continuity defects in the inferior alveolar or lingual nerves.

PATIENTS AND METHODS

Seven nerve repairs were performed in five patients (M:F = 1:4) with an age range of 16 to 56 years. The duration from injury to repair ranged from 4 to 30 months. Two inferior alveolar and five lingual nerves were repaired.

RESULTS

All seven patients had anesthesia by objective testing preoperatively and had a continuity defect at the time of operation. The size of the defects ranged from 2 to 15 mm. Two of the seven patients had some return of sensation, occurring in defects of 3 mm or smaller.

CONCLUSION

The results of this pilot study indicate that Gore-Tex tubing may not be effective in the repair of continuity defects except in those defects 3 mm or smaller, in which it may act as a protective barrier membrane rather than as a conduit.

The accuracy of clinical neurosensory testing for nerve injury diagnosis

PURPOSE

The accuracy of the clinical neurosensory test to diagnose trigeminal nerve injuries has never been statistically evaluated. The purpose of this study was to determine the statistical efficacy of the clinical neurosensory test using surgical findings as the "gold" standard, and to determine whether a correlation existed between the sensory impairment score obtained by preoperative testing and the degree of nerve injury found at surgery.

MATERIALS AND METHODS

A multisite, randomized, prospective, blinded, clinical trial was conducted on 130 patients with inferior alveolar nerve (IAN) and lingual nerve (LN) injuries. Preoperatively, patients were provided a sensory impairment score using a three-level drop-out clinical neurosensory test (NST), and blind comparisons were made with the surgical findings postoperatively.

RESULTS

The positive predictive and negative predictive values for LN-injured patients were 95% and 100%, respectively. The positive predictive and negative predictive values for IAN patients were 77% and 60%, respectively. There were statistically significant differences in the distribution of age, duration of injury, cause of injury, presence of neuropathic pain, presence of trigger pain, and degree of injury between the IAN and LN patient populations. There was a statistically significant positive relationship found between the sensory impairment score and the degree of nerve injury.

CONCLUSIONS

The NST is a clinically useful method to diagnose IAN and LN injuries. However, the NST results are less efficient for IAN injuries than LN injuries, and have a high incidence of false-positive (23%) and false-negative (40%) results when testing patients with IAN injuries. The different rates of statistical efficiency between the two groups of patients may be attributable to differences in prevalence and biologic covariates.

Recommendations for management of trigeminal nerve defects based on a critical appraisal of the literature

PURPOSE

Management of trigeminal nerve injuries continues to challenge oral and maxillofacial surgeons. The purpose of this review article is to apply the principles of evidence-based medicine (E-BM) to determine the optimal operative technique for managing defects involving the inferior alveolar (IAN) or lingual nerves when direct (ie, primary) repair is not feasible.

METHODS

To address the research purpose, the four steps of the E-BM critical appraisal process were applied: 1) identify the clinical problem, 2) efficiently search the literature, 3) select relevant articles and apply rules of evidence, and 4) apply the findings to patient care. Parameters for the literature search included using Medline to identify English language articles, publication dates from 1986 through 1996, and studies involving human subjects.

RESULTS

The studies reviewed showed that the clinical literature on operative management of trigeminal nerve injuries is sparse, preoperative and postoperative neurosensory examinations are poorly documented, and the data are derived completely from reports using case series methods. Given these limitations, the available literature suggests that 1) tension-free, primary (direct) suture repair of an injured nerve, if possible, provides optimal results; 2) if direct repair is not possible, autogenous nerve grafts should be used for acute injuries, for example, immediate nerve repair after tumor resection or at the time of acute repair after traumatic injury; and 3) if direct repair is not possible, autogenous nerve grafts or hollow conduits (entubulization) to bridge the defect are equally successful for delayed reconstruction of gaps of 3 cm or smaller.

CONCLUSIONS

Based on the weakness of the current literature, recommendations for future research include 1) better standardization and documentation of sensory deficits resulting from nerve injuries and their recovery, 2) using multicenter studies to accumulate large samples of patients rapidly, 3) using case series or prospective cohort study designs to assess the value of operative management of nerve injuries, and 4) progressing to randomized clinical trials to ascertain the optimal operative management of nerve injuries.

Lingual nerve paresthesia following third molar surgery: a retrospective clinical study

Lingual nerve anesthesia, paresthesia, and dysesthesia are possible side effects of third molar extraction. These unwanted complications are frequently disturbing to both the patient and practitioner. The incidence of lingual nerve damage following third molar surgery is more frequent than once thought. Six hundred questionnaires were sent to randomly selected Fellows of the American Association of Oral and Maxillofacial Surgeons in 50 states to determine the parameters surrounding this phenomenon. Of the 452 respondents, 76.05% reported having had patients with lingual anesthesia, dysesthesia, or paresthesia. Of all the reported cases, 18.64% of the cases failed to resolve. Of the reported cases, only three underwent surgical intervention. Because many cases of lingual nerve dysfunction do not resolve, it is important to inform patients that microsurgical nerve repair techniques are available as a modality of treatment following diagnosis. It has also been recommended that if the paresthesia does not resolve within 10 to 12 weeks, then management options including microsurgical nerve reconstruction within a short period of time should be discussed as a plan with the patient.

[Evaluating methods and effects of repairing injured lingual nerves on human]

We evaluated the regenerations of sense and taste on the anterior 2/3 of the tongue following repairing injured lingual nerve. Injured lingual nerves in 14 patients were repaired with anastomosis of the nerve epineurium. On the anterior 2/3 of the ipsilateral tongue, most of the fungiform papillae atrophied and disappeared, the sense and taste degenerated after severe injury to lingual nerve. Following repair of the injured lingual nerve with anastomosis of nerve epineurium, the papillae and their taste pores can regenerated, 50% of the patients recovered their tongue sense and 35.71% of the patients recovered their tongue taste 1 year after the repair. It is objective, accurate and reliable to evaluate the regenerations of sense and taste on the anterior 2/3 of the tongue after repair of injured lingual nerve by sensory test, taste evaluation, quantitative observation of fungiform papillae, and their taste pores.