Assessment of trigeminal nerve functions by quantitative sensory testing in patients and healthy volunteers

Gender differences in clinical presentations and sensory profiles in patients with fibromyalgia: implications of peripheral and central mechanisms

Introduction

Fibromyalgia has a high female predominance and research work has been focussing mainly on women.

Objectives

We aimed to answer (1) gender differences in pain scores and quality of life, (2) any gender-specific subgroups defined by quantitative sensory testing (QST), and (3) correlations of QST parameters with pain intensity and questionnaire scores.

Methods

We evaluated clinical presentations and QST profiles from 38 male and 38 age-matched female patients.

Results

Women reported significantly higher scores in average daily pain, daily sleep interference score, average weekly pain, weekly sleep interference score, and revised fibromyalgia impact questionnaire (rFIQ). Based on LOGA classification, L0G2, mechanical allodynia or hyperalgesia without abnormal sensory loss, was the most common QST subtype which accounted for 28.9% of men and 26.3% of women. Approximately 34.2% of men and 26.3% of women displayed loss of function of small fibres with an increased cold or warm detection threshold. Cold detection threshold was negatively correlated with pain intensity and functional impairment, suggesting a peripheral mechanism. Central sensitization, defined as allodynia and hyperalgesia to thermal or mechanical stimuli, was found in two-thirds of male and female patients. Mechanical pain sensitivity was positively correlated with the severity of pain and associated symptoms in women, but not men.

Conclusion

There was a marked gender difference in reported pain and quality of life. We have confirmed that central sensitization is a major mechanism for women. Our data suggested an important role of small fibre pathology in both men and women.

Recovery of the Infraorbital Nerve Following Open Reduction and Fixation Surgery of Zygomaticomaxillary Complex Fractures-A Prospective Cohort Study Based on Quantitative Sensory Testing

This study aimed to assess the sensory function of the infraorbital nerve in patients with fractures of the zygomatic complex who underwent open reduction and internal fixation at different time points using quantitative sensory testing, which was established by the German Neuropathic Pain Research Network, comprising a 7-item mechanical and thermal sensory test. A total of 21 patients (age range 17-46 y, 14 males) with unilateral zygomatic complex fractures were included. Quantitative sensory testing was conducted before the operation and at 1 week, 3 months, and 6 months operatively, with cold detection threshold, warmth detection threshold, cold pain threshold, heat pain threshold, mechanical detection threshold, mechanical pain threshold, pressure pain threshold, and vibration detection threshold being measured in bilateral infraorbital regions. Notable changes in sensitivity were observed in all values except for the mechanical pain threshold. In the majority of patients with zygomaticomaxillary complex fractures, infraorbital hypoesthesia was significantly improved within 3 months postoperatively, and almost complete recovery could be achieved by 6 months postoperatively.

Somatosensory and Gustatory Profiling in the Orofacial Region

Quantitative sensory testing (QST) is a standard procedure in medicine to describe sensory patterns in various pathologies. The aim of this prospective clinical study was to define reference values of the trigeminal nerve (V3), including taste qualities, to create a compatibility for sensory loss or gain in pathologies. Fifty-one patients were included, and a standardized testing battery with 11 QST parameters according to the German Research Network on Neuropathic Pain (DFNS) was applied complemented by quantitative gustatory assessments. Significant somatosensory differences were found between the test sites (MDT at the chin, WDT at the lower lip) but no effect was detected for gender, age, and between body types. Taste sensitivity was dependent on concentration, gender (females being more sensitive) and increasing age (for bitter and sour taste). We provide reference values for somatosensory and gustatory testing of the facial area. Our data facilitate the detection of neurosensory abnormalities in the orofacial region. This might also serve as a control setting for COVID-19.

Evaluation of Cold Sensitivity in Patients With Upper Extremity Nerve Compression Syndromes: A Scoping Review

PURPOSE

The aim of this study was to review the literature to determine the prevalence of cold sensitivity in upper extremity nerve compression syndromes and the impact of treating nerve compression syndromes on cold sensitivity.

METHODS

Following a standardized scoping review protocol, this study included interventional and observational study designs assessing patients with cold sensitivity and upper extremity nerve compression syndromes. Review articles, case reports, and small case series (n < 5) were excluded. The abstracts and eligible full texts were screened by 2 independent reviewers. Data were extracted and reported according to PRISMA extension for scoping reviews statement.

RESULTS

Three databases were searched (Ovid MEDLINE, Ovid EMBASE, and CINAHL on EBSCO); 274 references were reviewed. Fifteen studies from the database search and 8 studies from the reference search were eligible for this review (n = 23). Two interventional and 21 observational studies were identified. The most common method for assessing cold sensitivity was cold pain threshold testing (n = 12), followed by subjective patient reporting (n = 4). The Cold Intolerance Symptom Severity questionnaire was the most common validated patient-reported outcome questionnaire used in the studies (n = 3). Cold sensitivity was most commonly reported in carpal tunnel syndrome (96% of the studies). The prevalence of cold sensitivity in nerve compression syndromes ranged from 20% to 69%. Nerve decompression improved the severity of cold sensitivity in 5 of 6 studies where cold sensitivity was studied.

CONCLUSIONS

There is heterogenicity in the studies assessing cold sensitivity in nerve compression syndromes. Despite moderate prevalence in patients with carpal tunnel syndrome, cold sensitivity is understudied. Within the limitations of eligible studies reviewed, surgical decompression improved the severity of cold sensitivity in some studies.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Thermal quantitative sensory testing in burning mouth syndrome

OBJECTIVES

Subjects with burning mouth syndrome (BMS) have altered sensitivity and pain thresholds for thermal stimuli compared to a control group.

MATERIALS AND METHODS

Fourteen women and 6 men (average age = 62.60 years, median = 63.50) with BMS and a control group were tested using the method of thermal quantitative sensory testing (tQST) (tip, right, and left lateral border of the tongue, left thumb) to determine their heat/cold detection threshold (WDT/CDT) and heat/cold pain threshold (HPT/CPT).

RESULTS

Only the CPT values at the tip and both lateral border of the tongue show a statistically significant difference: tip of the tongue: sick = 12.0 ± 5.5 °C, median 14.2°C; healthy = 4.5 ± 2.9 °C; median = 6.4 °C; p = 0.000; right lateral border: sick = 8.55 ± 3.34 °C; healthy = 4.46 ± 1.90 °C; median 5.8 °C; p < 0.001; left lateral border: sick = 10.18 ± 3.94 °C¸ healthy = 4.15 ± 2.18 °C; median = 6.0 °C; p < 0.001.

CONCLUSIONS

BMS may be a combination of a dysfunction of free nociceptive nerve endings in the peripheral nervous system and impaired pain processing in the central nervous system.

CLINICAL RELEVANCE

This preliminary study provides hints to other causes of BMS. This offers the possibility of further therapeutic options.

Psychophysical characterisation of burning mouth syndrome-A systematic review and meta-analysis

BACKGROUND

Primary burning mouth syndrome (BMS) is an oro-facial disease with neuropathic characteristics. Psychophysics, such as quantitative sensory testing (QST), is used to sub-classify neuropathic pain syndromes, but their usefulness in characterising BMS is not yet clear.

OBJECTIVE

The aim of this study was to summarise and to quantitatively and qualitatively analyse the available information about QST findings in BMS, and to reflect on possible mechanisms of disease.

METHODS

In this systematic review and meta-analysis, different search strategies were used to screen for articles in PubMed, Embase, EBSCOhost, Cochrane Library, Web of Science, Google Scholar and two sources of conference abstracts. Primary clinical studies focused on QST assessment in patients with BMS were included. Data were synthesised qualitatively and quantitatively. Risk of bias was assessed following the AHRQ guidelines.

RESULTS

Thirteen articles with low to moderate risk of bias and one conference abstract were selected from 45 unique articles that were identified. Individually, the studies reported combinations of thermal and mechanical sensory impairments measured by QST. The meta-analysis showed significant sensory differences between patients and controls in warmth (effect size = 0.683; P < .05) and cold detection thresholds (effect size = -0.580; P < .001).

CONCLUSION

The results indicate that thermal sensitivity seems to be altered in patients with BMS compared to controls, suggesting a small-fibre neuropathy. However, study protocols were highly variable and heterogeneous. Therefore, studies with better designs and complete reporting of results should be performed to bring value to the use of psychophysics in the assessment of BMS.

Quantitative sensory testing of periauricular skin in healthy adults

The aim of this study was to investigate the test-retest reliability of quantitative sensory testing (QST) and mechanical sensitivity mapping of the periauricular skin. Twenty volunteers (10 men, 10 women) participated in two sessions at intervals of one week. Cold and warm detection threshold (CDT&WDT), cold and heat pain threshold (CPT&HPT), mechanical detection and pain threshold (MDT&MPT), pressure pain threshold (PPT) and two-point discrimination (2PD) were measured at five sites: bilateral subauricular and postauricular sites (LA, RA, LB, RB) and the dorsum of left hand (control). Pressure stimulation was applied at each of the four periauricular test sites. The test-retest reliability of the QST data implied fair to excellent agreement as evaluated by the intra-class correlation coefficients (ICC; all >0.4) for different days. There was no difference between each side in the QST parameters and mechanical sensitivity mapping (P ≥ 0.057). Significant differences between subauricular and postauricular sites were shown for WDT and PPT (P ≤ 0.028). NRS scores of mechanical sensitivity mapping showed significant effects of gender, site and point (P ≤ 0.040). QST and mechanical sensitivity mapping can be considered to be a reliable technique to assess somatosensory function of the periauricular skin.

Sex, blinking, and dry eye

Blinking sustains the corneal tear film generated by sexually dimorphic lacrimal and meibomian glands. Our study examines whether trigeminal control of blinking is also sexually dimorphic by investigating trigeminal reflex blinking, associative blink modification, and spontaneous blinking in male and female rats before and after unilateral dry eye caused by exorbital gland removal. Before gland removal, female rats exhibited a lower threshold for evoking trigeminal reflex blinks, a weaker effect of associative blink modification, and longer-duration spontaneous blinks than males. Spontaneous blink rate, reflex blink excitability, and occurrence of blink oscillations did not differ between the sexes. Reanalysis of previous data showed that humans showed the same blink sexual dimorphisms as rats. During the first 2 wk of dry eye, trigeminal blink circuit excitability and blink oscillations steadily rose in male rats, whereas excitability and blink oscillations did not change in females. Following dry eye, spontaneous blink duration increased for both males and females, whereas spontaneous blink rate remained constant for males but decreased for females. The associative modification treatment to depress trigeminal blink amplitude initially produced blink depression in males that converted to blink potentiation as trigeminal excitability rose, whereas females exhibited progressively more blink depression. These data indicated that dry eye increased excitability in male trigeminal reflex blink circuits at the expense of circuit modifiability, whereas trigeminal modifiability increased in females. This increased modifiability of female trigeminal blink circuits with dry eye may contribute to the preponderance of females developing the focal dystonia, benign essential blepharospasm.NEW & NOTEWORTHY All the elements controlling the corneal tear film are sexually dimorphic. Blinking, which smooths and maintains the tear film, also exhibits sex differences. Dry eye increases the sexual dimorphisms of blinking, including increased exaggeration of excitability in males and enhanced modifiability of the female trigeminal complex. This increased modifiability may explain female predominance in the development of the focal dystonia, benign essential blepharospasm.

Satisfactory outcomes after orthognathic surgery with surgically assisted rapid maxillary expansion using a hybrid device

The self-reported functional outcomes, clinical findings, and results of dental cast analysis before and after orthognathic surgery with surgically assisted rapid maxillary expansion (SARME) using a hybrid rapid maxillary expander (RME) were evaluated. Data were collected from 43 patients who underwent orthognathic surgery with SARME using a hybrid RME between 2001 and 2013. The patients were recruited during a follow-up clinical examination and were required to complete a questionnaire about their opinions and self-reported functional outcomes. Dental casts were used to analyze posttreatment palatal expansion. The mean follow-up time was 68 months (range: 25-135 months). The most common indication for SARME was the presence of a crossbite. Of the 30 patients who underwent a follow-up clinical examination (69.8% answer rate), 4 (13.3%) had symptoms of temporomandibular disorder (TMD), 1 (3.3%) experienced myalgia, and 3 (10.0%) experienced arthralgia on clinical palpation. Cast analysis revealed significant palatal expansion. The intercanine distance, intermolar distance, and palatal height were increased by 3, 5, and 2 mm, respectively. Overall, the patients were satisfied with the preoperative information, improved functions, and aesthetic results. The prevalence of TMD symptoms and other side effects following orthognathic surgery with SARME using a hybrid RME was low, and significant palatal expansions were achieved.

An exploration of sensory processing patterns and their association with demographic factors in healthy adults

Purpose

Previous research has provided limited evidence on whether and how demographic factors associate with sensory processing patterns (SPP) in adults. This paper aims to examine relationships between SPPs and sociodemographic factors of age, sex, education and ethnicity in healthy adults.

Design/methodology/approach

A cross-sectional study design was used. A total of 71 adult participants was recruited from the community, using convenience sampling. Each participant completed the Adolescent/Adult Sensory Profile (AASP) and the Depression Anxiety Stress Scales – short version (DASS-21). Demographic information on age, sex, education and ethnicity was collected. Results were analysed using descriptive statistics and multivariate analyses of covariance (MANCOVA).

Findings

SPPs, as measured by the AASP, were significantly correlated to demographic factors of age and education after controlling for emotional distress using the DASS-21. A statistically significant multivariate effect was found across the four dependent variables (low registration, seeking, sensitivity and avoiding) for the age category, F = 6.922, p = 0.009, ηp2 = 0.145, in the presence of a covariate DASS. The education category showed significance only in the seeking domain (p = 0.008, ηp2 = 0.10) after controlling for DASS. There was no significant correlation between SPPs and gender or ethnicity. Results also indicated that mean scores of participants in this study were “similar to most people” as standardised in the AASP.

Research limitations/implications

This was a cross-sectional study with limitations including that the study used a relatively small sample and was based on self-reported healthy participants.

Practical implications

SPPs may correlate with healthy adults’ age and to a lesser extent education. This suggests that it might be helpful to consider such demographic factors when interpreting SPPs in clinical populations, although further research in larger samples is needed to reach firmer conclusions about possible implications of demographic variables.

Originality/value

The findings in this paper add to the growing evidence that suggest that SPPs vary with sociodemographic factors.

[Possibilities of thermographic rating the level of microcirculation with local anesthesia in dentistry]

It is known that the reduction of blood vessels by epinephrine that are part of the local anesthetic leads to a decrease in oxygen intake and the development of hypoxia, which has a significant effect on the excitability of nerve fibers. This is due to the fact that epinephrine is present in the local anesthetic cartridge, which helps to reduce, until termination, microcirculation in the depot area, which leads to local hypothermia. With the introduction of local anesthetics, the temperature of which is significantly lower than the depot temperature, the patient experiences severe discomfort, which is associated with unsuccessful local anesthesia. The goal of the study was the need to analyze the feasibility of using the thermography method in assessing the degree of ischemia of the soft tissues of the maxillofacial region against the background of local anesthesia with a different concentration of epinephrine in dentistry.

MATERIAL AND METHODS

In the pilot study, 22 healthy volunteers aged between 29-35 years of both sexes participated. To assess the degree of external vasoconstriction, a buccal region was chosen near the maxilla. Infiltration anesthesia was used with a 4% solution of articaine with epinephrine 1: 100 000 and 1: 200 000 at a dosage of 0.5-0.7 ml. The temperature distribution in the study area was estimated using a thermal imager Nec InfReC Thermo Gear G30.

RESULTS

The study showed that the use of epinephrine in local anesthetics naturally has a moderate effect on hemodynamics in areas adjacent to the anesthesia depot. When using a low concentration of epinephrine (1:200 000), the projection hyperthermia of the skin is determined. Perhaps this is due to the activation of microcirculation due to an increase in capillary blood flow in the region above the zone of action of the epinephrine. From the point of view of physiological arterial hyperemia, this mechanism carries positive properties, since leads to an increase in tissue oxygenation. When using a high concentration of epinephrine (1:100 000), the zone of hypothermia of the skin is determined, which corresponds to the phenomenon of angiospastic ischemia.

Quantitative sensory testing (QST) in the orofacial region of healthy Chinese: influence of site, gender and age

OBJECTIVE

To establish a preliminary thermal and mechanical somatosensory profile using a standardized quantitative sensory testing (QST) to investigate site, gender and age differences in healthy Chinese.

MATERIALS AND METHODS

Twenty younger (age: 20-40 years, 10 men, 10 women) and twenty older (age: 41-61 years, 10 men, 10 women) healthy participants completed the study. Cold detection threshold (CDT), warm detection threshold (WDT), cold pain threshold (CPT), heat pain threshold (HPT), mechanical detection threshold (MDT) and mechanical pain threshold (MPT) were measured at five sites: Left hand, bilaterally at the mental area, tip of tongue and the lower lip mucosa. Mixed model ANOVAs with repeated measures were used to analyze the data.

RESULTS

MDT(p < .001) and MPT (p < .05) were significantly higher on the hand compared to the mental areas. The CDT ( p = .006) was significantly higher and WDT (p < .001) was significantly lower at the tongue compared to lip mucosa and CDT (p < .001) was higher at the tongue mucosa than at the mental areas. WDT (p < .001) and HPT (p < .05) were significantly higher at the tip of the tongue and the lower lip mucosa compared to the mental areas. Significantly lower sensitivity for WDT (p < .001) and CDT (p = .004) were found in the older group compared to the younger group. Significant gender differences were found with less sensitivity for WDT (p = .024) and MDT (p = .003) in men compared to women.

CONCLUSIONS

Application of standardized QST can provide valuable information of orofacial somatosensory phenotypes in a Chinese population. Age, gender and site are mandatory to control for.

Quantitative sensory testing for assessment of somatosensory function in human oral mucosa: a review

OBJECTIVE

This narrative review provides an overview of the quantitative sensory testing (QST) to assess somatosensory function in human oral mucosa.

MATERIAL AND METHODS

A literature search was conducted in the PubMed database to identify studies in vivo on human oral mucosa using QST methods. A list of 149 articles was obtained and screened. A total of 36 relevant articles remained and were read in full text. Manual search of the reference lists identified eight additional relevant studies. A total of 44 articles were included for final assessment.

RESULTS

The included studies were divided into six categories according to the study content and objective. In each category, there was a great variety of aims, methods, participants and outcome measures. The application of QST has nevertheless helped to monitor somatosensory function in experimental models of intraoral pain, effects of local anesthesia, after oral and maxillofacial surgery and after prosthodontic and orthodontic treatment.

CONCLUSIONS

QST has been proved to be sufficiently stable and reliable, and valuable information has been obtained regarding somatosensory function in healthy volunteers, special populations and orofacial pain patients. However, as most of the studies were highly heterogeneous, the results are difficult to compare quantitatively. A standardized intraoral QST protocol is recommended and expected to help advance a mechanism-based assessment of neuropathies and other intraoral pain conditions.

Influence of Electroacupuncture and Laser-Acupuncture on Treating Paresthesia in Patients Submitted to Combined Orthognathic Surgery and Genioplasty

Objective: The goal of this research was to observe the influence of electroacupuncture (EA) and laser-acupuncture on the return of tactile/pain sensitivity in patients who underwent orthognathic surgery. Materials and Methods: Thirty volunteers subjected to orthognathic surgery were evaluated and randomly divided into 2 groups, in which 3 treatments were evaluated: control (n = 30) (G0, medication + placebo laser treatment) and 2 experimental treatments (n = 15) (G1, medication + EA) or G2 (medication + laser-acupuncture). The control group had n = 30 because for each experimental treatment conducted on a volunteer's hemi-face, there was a control treatment on the other hemi-face. In G1, medication was given with EA, with needles placed at predetermined points (ST 4 [Dicang], M-HN-18 [Jiachengjiang], CV 24 [Chengjiang], ST 5 [Daying], ST 6 [Jiache], and point A1 [YNSA]). For electrostimulation, the device used delivered transcutaneous electrical nerve stimulation of a burst type, with intensity and frequency variations of T = 220 ms and F = 4 Hz (30 minutes, 2 × /week). In G2, in addition to the medication, laser irradiation (at 780 nm) was applied on acupuncture points (at 0.04 cm², 70 mW, 6 s/point, 0.42 J/point, 10 J/cm², 2 × /week). All volunteers were evaluated before and during the 4 months following the surgery. Tactile sensitivity was assessed by mechanical brushing (brush #s 2 and 12) and by a 2-point discrimination test, using a bow compass. A pain test was performed with a pulp electrical test that stimulates intact nerves of the dentin-pulp complex. A Kaplan-Meier test was performed, and survival curves were plotted for comparison between groups. Cox regression analysis was also conducted (α = 0.05). Results: There were no statistically significant differences among the groups for the 2-point discrimination test (brushes #2 and #12) on the buccal mucosa region and for the pulp test on all evaluated regions. However, the tactile test using brush #12 revealed significant differences between G1 and the other groups when considering the lower lip (P = 0.024) and chin (P = 0.028) areas. Conclusions: Only EA was able to influence-using the brushing test (brush #12)-the return of tactile sensitivity on the chin and lower lip positively after combined orthognathic surgery and genioplasty.

Assessment of lingual nerve functions after smoking cessation

OBJECTIVE

Cigarette smoking is associated with a variety of oral diseases. A previous study showed a reduction of thermal sensitivity in the innervation area of the lingual nerve in smokers possibly caused by a degeneration of thermosensitive receptors as a consequence of smoking. The current study investigates somatosensory changes in ex-smokers.

MATERIALS AND METHODS

Sensory functions in innervation areas of lingual nerve were investigated in 40 ex-smokers by psychophysical means. Functions of lingual nerve in 40 ex-smokers were compared to those in 40 smokers and 40 non-smokers. Subjects were investigated using quantitative sensory testing (QST, cold and warm detection, thermal sensory limen, heat and cold pain, and mechanical detection).

RESULTS

Significant differences were found in both groups, ex-smokers and smokers compared to non-smokers. Cold (p < .001), warm (ex-smokers: p < .01; smokers: p < .001) detection thresholds and thermal sensory limen (p < .001) showed significantly lower sensitivity in ex-smokers and smokers in comparison to non-smokers.

CONCLUSIONS

The lower temperature sensitivity of ex-smokers compared to that in non-smokers indicates a reduction of somatosensory function of the tongue, possibly caused by irreversible nerve degeneration associated with smoking. Influencing factors leading to sensory changes could be modulation of thermo-receptors, demyelination as well as a change of the epithelial structure.

Neurophysiological changes associated with implant-associated augmentation procedures in the lower jaw

BACKGROUND

Neurophysiological changes after oral and maxillofacial surgery remain one of the topics of current research.

PURPOSE

This study evaluated if implant placement associated with augmentation procedures increases the possibility of sensory disturbances or result in impaired quality of life during the healing period.

MATERIAL AND METHODS

Patients who had obtained an implant placement in the lower jaw in combination with augmentation procedures were examined by implementing a comprehensive Quantitative Sensory Testing (QST) protocol for extra- and intraoral use. As augmentation procedures, we used Guided Bone Regeneration (Group A) and Customized Bone Regeneration (Group B) techniques. Patients were tested bilaterally at the chin and mucosal lower lip. Results were compared to a group without augmentation procedures (Group C). Patients' quality of life and psychological comorbidity after the surgical procedures was assessed with the Oral Health Impact Profile and the Hospital Anxiety and Depression Scale.

RESULTS

For groups A (n = 20) and B (n = 8), mechanical QST parameters showed no significant differences in all qualities of the inferior alveolar nerve compared to the contralateral side and compared to the nonaugmentation control group (n = 32) as well. Evaluation of quality of life and psychological factors showed no statistical differences.

CONCLUSIONS

Augmentation procedures did not increase sensory disturbances, indicating no changes in the neurophysiological pathways. Extended augmentation procedures did not lead to sensory changes either or result in an impaired quality of life or modified anxiety and depression scores.

Post-operative orofacial pain, temporomandibular dysfunction and trigeminal sensitivity after recent pterional craniotomy: preliminary study

BACKGROUND

Surgical trauma at the temporalis muscle is a potential cause of post-craniotomy headache and temporomandibular disorders (TMD). The aim of this study was to evaluate the prevalence of pain, masticatory dysfunction and trigeminal somatosensory abnormalities in patients who acquired aneurysms following pterional craniotomy.

METHODS

Fifteen patients were evaluated before and after the surgical procedure by a trained dentist. The evaluation consisted of the (1) research diagnostic criteria for TMD, (2) a standardized orofacial pain questionnaire and (3) a systematic protocol for quantitative sensory testing (QST) for the trigeminal nerve.

RESULTS

After pterional craniotomy, 80% of the subjects, 12 patients, developed orofacial pain triggered by mandibular function. The pain intensity was measured by using the visual analog scale (VAS), and the mean pain intensity was 3.7. The prevalence of masticatory dysfunction was 86.7%, and there was a significant reduction of the maximum mouth opening. The sensory evaluation showed tactile and thermal hypoesthesia in the area of pterional access in all patients.

CONCLUSIONS

There was a high frequency of temporomandibular dysfunction, postoperative orofacial pain and trigeminal sensory abnormalities. These findings can help to understand several abnormalities that can contribute to postoperative headache or orofacial pain complaints after pterional surgeries.

[Zygomaticomaxillary complex fractures with infraorbital nerve damage]

Zygomaticomaxillary complex (ZMC) fracture is a common type of maxillofacial fracture. In addition to facial depression and diplopia, paresthesia of the lower eyelid, malar regions, nose skin, upper lip skin, and mucous membranes occurs because of infraorbital nerve injury. This article reviewed the anatomy, diagnosis, assessment, treatment, and prognosis of ZMC fracture-related infraorbital nerve injury.

Profiling intraoral neuropathic disturbances following lingual nerve injury and in burning mouth syndrome

Background

The aim of the study was to analyse intraoral neurophysiological changes in patients with unilateral lingual nerve lesions as well as patients with Burning Mouth Syndrome (BMS) by applying a standardized Quantitative Sensory Testing (QST) protocol.

Methods

The study included patients suffering from a peripheral lesion of the lingual nerve (n = 4), from BMS (n = 5) and healthy controls (n = 8). Neurophysiological tests were performed in the innervation areas of the tongue bilaterally. For BMS patients the dorsal foot area was used as reference.

Results

For patients with peripheral lesion of the lingual nerve the affected side of the tongue showed increased thresholds for thermal (p < 0.05–0.001) and mechanical (p < 0.01–0.001) QST parameters, indicating a hypoesthesia and thermal hypofunction. In BMS patients, a pinprick hypoalgesia (p < 0.001), a cold hyperalgesia (p < 0.01) and cold/warmth hypoesthesia (p < 0.01) could be detected.

Conclusions

The results of this study verified the lingual nerve lesion in our patients as a peripheral dysfunction. The profile showed a loss of sensory function for small and large fibre mediated stimuli. A more differentiated classification of the lingual nerve injury was possible with QST, regarding profile, type and severity of the neurologic lesion. BMS could be seen as neuropathy with variable central and peripheral contributions among individuals resulting in chronic pain.

Laser Therapy in the Treatment of Paresthesia: A Retrospective Study of 125 Clinical Cases

OBJECTIVE

The aim of this retrospective study was to evaluate the effectiveness of laser therapy for acceleration and recovery of nerve sensitivity after orthognathic or minor oral surgeries, by analysis of clinical records of patients treated at the Special Laboratory of Lasers in Dentistry (LELO, School of Dentistry, University of São Paulo), throughout the period 2007-2013.

BACKGROUND DATA

Nerve tissue lesions may occur during various dental and routine surgical procedures, resulting in paresthesia. Laser therapy has been shown to be able to accelerate and enhance the regeneration of the affected nerve tissue; however, there are few studies in the literature that evaluate the effects of treatment with low-power laser on neural changes after orthognathic or minor oral surgeries.

METHODS

A total of 125 clinical records were included, and the data on gender, age, origin of the lesion, nerve, interval between surgery and onset of laser therapy, frequency of laser irradiation (one or two times per week), final evolution, and if there was a need to change the irradiation protocol, were all recorded. These data were related to the recovery of sensitivity in the affected nerve area. Descriptive analyses and modeling for analysis of categorical data (α=5%) were performed.

RESULTS

The results from both analyses showed that the recovery of sensitivity was correlated with patient age (p=0.015) and interval between surgery and onset of laser therapy (p=0.002).

CONCLUSIONS

Within the limits of this retrospective study, it was found that low- power laser therapy with beam emission band in the infrared spectrum (808 nm) can positively affect the recovery of sensitivity after orthognathic or minor oral surgeries.

Neurophysiological changes associated with implant placement

OBJECTIVES

The objective of the study was to evaluate the feasibility of a standardized Quantitative Sensory Testing (QST) protocol extra- and intraoral in patients to detect and quantify sensory disturbances of the inferior alveolar nerve due to the proximity of implantation procedures to the inferior alveolar nerve canal.

MATERIAL AND METHODS

Patients who had obtained an implant placement were examined by implementing a comprehensive QST protocol for extra- and intraoral use. The study included 33 patients after implant placement in the lower jaw and one patient suffering from an inferior alveolar nerve injury. Patients were tested bilaterally (chin and mucosal lower lip).

RESULTS

Comparing the implanted vs. the control side, QST parameters revealed no significant neurophysiological changes in all parameters. Evaluating the development of sensory disturbances in dependency of the proximity of the implant to the inferior alveolar nerve canal, mechanical QST parameters showed no significant correlation. The mean distance of the inserted implant to the inferior nerve canal was 2.65 ± 1.75 mm. In the case of one patient suffering from impairment of the nerve function due to implant placement, we found abnormal sensory responses to touch coexisting with numbness and temperature algesia.

CONCLUSIONS

Monitoring of trigeminal nerve fiber functions by QST intra- and extraoral is feasible to evaluate oral sensory pattern after implantation procedures. Sensory disturbances of the inferior alveolar nerve were shown to be avoided by keeping an average safety zone of 2.65 mm between implant and nerve.

Quantitative sensory testing in pain management

Quantitative sensory testing (QST), a set of noninvasive methods used to assess sensory and pain perception, has been used for three decades. The precision of the instruments and the uninvasiveness encouraged many QST-based trials. The developments made have benefited multiple disciplines. QST relies on analysis of an individual's response to external stimuli, reflecting the integrity of the PNS and the sensory pathway. The sensory pathway cannot be assessed in isolation from the affective and cognitive characteristics of patients or testers. Many variables potentially affect the reliability and reproducibility of QST, which after all, is designed for the testing of individuals by other individuals. Several decades of QST research have yielded exciting contributions, but the future of QST cannot be fully known.

Controversies in fat perception

Nutritional fat is one of the most controversial topics in nutritional research, particularly against the background of obesity. Studies investigating fat taste perception have revealed several associations with sensory, genetic, and personal factors (e.g. BMI). However, neuronal activation patterns, which are known to be highly sensitive to different tastes as well as to BMI differences, have not yet been included in the scheme of fat taste perception. We will therefore provide a comprehensive survey of the sensory, genetic, and personal factors associated with fat taste perception and highlight the benefits of applying neuroimaging research. We will also give a critical overview of studies investigating sensory fat perception and the challenges resulting from multifaceted methodological approaches. In conclusion, we will discuss a multifactorial approach to fat perception to gain a better understanding of the underlying mechanisms that cause varying fat sensitivity which could be responsible for overeating. Such knowledge might be beneficial in new treatment strategies for obesity and overweight.

The quantitative sensory testing is an efficient objective method for assessment of nerve injury

BACKGROUND

This study evaluated Somatosensory evoked potentials (SEP), Quantitative sensory testing (QST), and thermography as diagnostic methods for nerve injury.

METHODS

From 2006 through 2011, 17 patients (mean age: 50.1 years) from OOOO Hospital who sought care for altered sensation after dental implant treatment were identified. The mean time of objective assessment was 15.2 months after onset.

RESULTS

SEP of Inferior alveolar nerve(IAN) was 15.87 ± 0.87 ms on the normal side and 16.18 ± 0.73 ms on the abnormal side. There was delayed N20 latency on the abnormal side, but the difference was not statistically significant. In QST, the abnormal side showed significantly higher scores of the current perception threshold at 2 KHz, 250 Hz, and 5 Hz. The absolute temperature difference was 0.55°C without statistically significance.

CONCLUSION

These results indicate that QST is valuable as an objective method for assessment of nerve injury.

Evaluation of the anesthetic effect of epinephrine-free articaine and mepivacaine through quantitative sensory testing

Introduction

Long lasting anesthesia of the soft tissue beyond the dental treatment affects patients in daily routine. Therefore a sophisticated local anesthesia is needed. The purpose of this study was an evaluation of the clinical use of epinephrine-free local anesthetic solutions in routine short-time dental treatments.

Materials and methods

In a prospective, single-blind, non-randomized and controlled clinical trial, 31 patients (16 male, 15 female patients) undergoing short-time dental treatment under local anesthesia (plain solutions of articaine 4% and mepivacaine 3%) in area of maxillary canine were tested with quantitative sensory testing QST. Paired-Wilcoxon-testing (signed-rank-test) and Mc Nemar tests have been used for statistical results.

Results

Significant differences in all tested parameters to the time of measurements were found. Mepivacaine showed a significantly stronger impact for the whole period of measurement (128 min) on thermal and mechanical test parameters and to the associated nerve fibers.

Conclusion

Plain articaine shows a faster onset of action associated with a shorter time of activity in comparison to plain mepivacaine. In addition to this articaine shows a significant low-graded effect on the tested nerve-fibers and therefore a least affected anesthesia to the patient. The clinical use of an epinephrine-free anesthetic solution can be stated as possible option in short dental routine treatments to the frequently used vasoconstrictor containing local anesthetics. Patients may benefit from shorter numbness.

Inferior alveolar nerve injury after mandibular third molar extraction: a literature review

Objectives

The purpose of this study was to systematically review the comprehensive overview of literature data about injury to the inferior alveolar nerve after lower third molar extraction to discover the prevalence of injury, the risk factors, recovery rates, and alternative methods of treatment.

Material and Methods

Literature was selected through a search of PubMed electronic databases. Articles from January 2009 to June 2014 were searched. English language articles with a minimum of 6 months patient follow-up and injury analysis by patient’s reporting, radiographic, and neurosensory testing were selected.

Results

In total, 84 literature sources were reviewed, and 14 of the most relevant articles that are suitable to the criteria were selected. Articles were analyzed on men and women. The influence of lower third molar extraction (especially impacted) on the inferior alveolar nerve was clearly seen.

Conclusions

The incidence of injury to the inferior alveolar nerve after lower third molar extraction was about 0.35 - 8.4%. The injury of the inferior alveolar nerve can be predicted by various radiological signs. There are few risk factors that may increase the risk of injury to the nerve such as patients over the age of 24 years old, with horizontal impactions, and extraction by trainee surgeons. Recovery is preferable and permanent injury is very rare.

Age and strength influences on lingual tactile acuity

Sensory function during the oral processing of liquids is thought to play a key role in informing the tailoring of swallowing motor behaviours to the flow characteristics of the bolus. In addition to taste receptors, the mouth and tongue house trigeminal nerve receptors that support the sensory detection of bolus size, shape (stereognosis), mass, temperature and movement. Recent studies suggest that healthy adults lose tongue strength with advancing age. However, little is known about changes in the sensory function of the tongue attributable to age, or associated with reductions in strength. In this study, we explored lingual tactile acuity in healthy young and older adults, and measured the relationship between tactile acuity and measures of tongue strength. The results showed an age-related reduction in lingual tactile acuity that was not explained by variations in tongue strength.

PRACTICAL APPLICATIONS

Sensory motor interactions are a topic of interest in understanding the processing activities that take place in the mouth during eating and swallowing. In this paper, we explore a test of sensory acuity in the mouth, in which the tongue is used to "read" embossed letters on Teflon strips. Our questions were to determine whether sensory acuity for this task declines with age, or with age-related reductions in tongue strength. We determined that older people perform this task with less accuracy, suggesting some changes in oral sensory function with age. However, these changes were not related to tongue strength. The findings suggest that strength does not play a major role in the kind of sensory discrimination task tested in this study.

Altered thermal sensitivity in facial skin in chronic whiplash-associated disorders

There is a close functional relationship between the jaw and neck regions and it has been suggested that trigeminal sensory impairment can follow whiplash injury. Inclusion of manageable routines for valid assessment of the facial sensory capacity is thus needed for comprehensive evaluations of patients exposed to such trauma. The present study investigated facial thermal thresholds in patients with chronic whiplash-associated disorders (WADs) with both a qualitative method and quantitative sensory testing (QST). Ten women with pain and dysfunction following a whiplash injury were compared to 10 healthy age-matched women. Thermal detection thresholds were assessed by qualitative chair-side testing and by QST according to the method-of-limits. Seven test sites in the facial skin (overlying each trigeminal branch bilaterally, and the midpoint of the chin) were examined. The detection warm and cold thresholds were defined as the mean values of 10 individual thresholds. For the WAD patients, the qualitative assessment demonstrated both reduced and increased sensitivity compared to the healthy, whereas QST systematically showed significantly higher detection thresholds (i.e., decreased sensitivity) for both cold and warm stimuli. For the individuals who were assessed as having increased sensitivity in the qualitative assessment, the QST displayed either normal or higher thresholds, i.e., decreased sensitivity. The results suggest that QST is more sensitive for detecting thermal sensory disturbances in the face than a qualitative method. The impaired thermal sensitivity among the patients corroborates the notion of altered thermal detection capacity induced by WAD-related pain.

[Quantitative Sensory Testing in the facial area: a review]

Quantitative Sensory Testing is an established method to evaluate somatosensory function. In the facial area, the procedures depend on the localisation of disorders and the modalities of interest. The test stimuli are of thermal or mechanical nature (touch, pain, vibration, or pressure stimuli). According to the protocol of the German Neuropathic Pain Network, comprehensive information on the function of afferent nerves can be generated in the facial area as well. Standard values have been obtained for the cheek and intraoral mucosa. For various orofacial pain conditions, studies concerning the somatosensory function are available. Changed functional patterns are not limited to neuropathic pain, but also occur in other orofacial pain conditions, indicating, for example, central sensitisation. The standardised collection of QST parameters may improve the understanding of the pathophysiology of orofacial pain and effect therapeutic approaches. Comprehensive studies may lead to the development of specific screenings that are feasible in a clinical setting.

Verification of nerve integrity after surgical intervention using quantitative sensory testing

PURPOSE

The aim of this study was to apply a standardized Quantitative Sensory Testing (QST) approach in patients to investigate whether oral surgery can lead to sensory changes, even if the patients do not report any sensory disturbances. Furthermore, this study determines the degree and duration of possible neuronal hyperexcitability due to local inflammatory trauma after oral surgery.

PATIENTS AND METHODS

Orofacial sensory functions were investigated by psychophysical means in 60 patients (30 male, 30 female) in innervation areas of infraorbital nerves, mental nerves and lingual nerves after different interventions in oral surgery. The patients were tested 1 week, 4 weeks, 7 weeks, and 10 weeks postoperatively. As controls for bilateral sensory changes after unilateral surgery, tests were additionally performed in 20 volunteers who did not have any dental restorations.

RESULTS

No differences were found between the control group and the control side of the patients. Although not 1 of the patients reported paresthesia or other sensory changes postoperatively, QST detected significant differences between the control and the test side in the mental and lingual regions. Test sides were significantly less sensitive for thermal parameters (cold, warm, and heat). No differences were found in the infraorbital region. Patients showed significantly decreased pain pressure thresholds on the operated side. QST monitored recovery over time in all patients.

CONCLUSIONS

The results show that oral surgery can lead to sensory deficits in the mental and lingual region, even if the patients do not notice any sensory disturbances. The applied QST battery is a useful tool to investigate trigeminal nerve function in the early postoperative period. In light of the increasing forensic implication, this tool can serve to objectify clinical findings.

Injury of the Inferior Alveolar Nerve during Implant Placement: a Literature Review

Objectives

The purpose of present article was to review aetiological factors, mechanism, clinical symptoms, and diagnostic methods as well as to create treatment guidelines for the management of inferior alveolar nerve injury during dental implant placement.

Material and Methods

Literature was selected through a search of PubMed, Embase and Cochrane electronic databases. The keywords used for search were inferior alveolar nerve injury, inferior alveolar nerve injuries, inferior alveolar nerve injury implant, inferior alveolar nerve damage, inferior alveolar nerve paresthesia and inferior alveolar nerve repair. The search was restricted to English language articles, published from 1972 to November 2010. Additionally, a manual search in the major anatomy, dental implant, periodontal and oral surgery journals and books were performed. The publications there selected by including clinical, human anatomy and physiology studies.

Results

In total 136 literature sources were obtained and reviewed. Aetiological factors of inferior alveolar nerve injury, risk factors, mechanism, clinical sensory nerve examination methods, clinical symptoms and treatment were discussed. Guidelines were created to illustrate the methods used to prevent and manage inferior alveolar nerve injury before or after dental implant placement.

Conclusions

The damage of inferior alveolar nerve during the dental implant placement can be a serious complication. Clinician should recognise and exclude aetiological factors leading to nerve injury. Proper presurgery planning, timely diagnosis and treatment are the key to avoid nerve sensory disturbances management.

Guidelines and recommendations for assessment of somatosensory function in oro-facial pain conditions--a taskforce report

The goals of an international taskforce on somatosensory testing established by the Special Interest Group of Oro-facial Pain (SIG-OFP) under the International Association for the Study of Pain (IASP) were to (i) review the literature concerning assessment of somatosensory function in the oro-facial region in terms of techniques and test performance, (ii) provide guidelines for comprehensive and screening examination procedures, and (iii) give recommendations for future development of somatosensory testing specifically in the oro-facial region. Numerous qualitative and quantitative psychophysical techniques have been proposed and used in the description of oro-facial somatosensory function. The selection of technique includes time considerations because the most reliable and accurate methods require multiple repetitions of stimuli. Multiple-stimulus modalities (mechanical, thermal, electrical, chemical) have been applied to study oro-facial somatosensory function. A battery of different test stimuli is needed to obtain comprehensive information about the functional integrity of the various types of afferent nerve fibres. Based on the available literature, the German Neuropathic Pain Network test battery appears suitable for the study of somatosensory function within the oro-facial area as it is based on a wide variety of both qualitative and quantitative assessments of all cutaneous somatosensory modalities. Furthermore, these protocols have been thoroughly described and tested on multiple sites including the facial skin and intra-oral mucosa. Standardisation of both comprehensive and screening examination techniques is likely to improve the diagnostic accuracy and facilitate the understanding of neural mechanisms and somatosensory changes in different oro-facial pain conditions and may help to guide management.

Analysis of trigeminal nerve disorders after oral and maxillofacial intervention

Background

Quantitative sensory testing (QST) is applied to evaluate somatosensory nerve fiber function in the spinal system. This study uses QST in patients with sensory dysfunctions after oral and maxillofacial surgery.

Methods

Orofacial sensory functions were investigated by psychophysical means in 60 volunteers (30 patients with sensory disturbances and 30 control subjects) in innervation areas of the infraorbital, mental and lingual nerves. The patients were tested 1 week, 4 weeks, 7 weeks and 10 weeks following oral and maxillofacial surgery.

Results

QST monitored somatosensory deficits and recovery of trigeminal nerve functions in all patients. Significant differences (p < 0.05) between control group and patients were shown for cold, warm and mechanical detection thresholds and for cold, heat and mechanical pain thresholds. Additionally, QST monitored recovery of nerve functions in all patients.

Conclusion

QST can be applied for non-invasive assessment of sensory nerve function (Aβ-, Aδ- and C-fiber) in the orofacial region and is useful in the diagnosis of trigeminal nerve disorders in patients.

Impaired somatosensation in tongue mucosa of smokers

Smoking has been indicated as a risk factor for oral diseases and can lead to altered sense of taste. So far, the effects of sensory changes on the tongue are not investigated. In this study, quantitative sensory testing was used to evaluate somatosensory function in the lingual region. Eighty healthy volunteers were investigated (20 smokers, 20 non-smokers). Subjects were bilaterally tested in innervation areas of lingual nerves. Thresholds of cold and warm detection, cold and heat pain, and mechanical detection were determined. As control for systemic, extraoral effects of smoking, tests were additionally performed in 40 volunteers (20 smokers, 20 non-smokers) on the skin of the chin innervated by the mental branch of the trigeminal nerve. Cold (p < 0.001), warm detection thresholds (p < 0.001), and thermal sensory limen (p < 0.001) showed higher sensitivity in non-smokers as compared to smokers. Heat pain and mechanical detection, as well as all tests in the skin of the chin, showed no significant differences. The impaired temperature perception in smokers indicates a reduction of somatosensory functions in the tongue, possibly caused by nerve degeneration associated with smoking. Possible systemic effects of smoking do not seem to affect extraoral trigeminal branches.