An aggressive pregnancy epulis with extensive alveolar bone resorption and tooth displacement.

Pregnancy epulis is a common and benign vascular tumor that reaches 5% of pregnant women; it respects adjacent structures, such as bone, teeth, and sinus mucosa. This paper reports a rare case of extensive pregnancy epulis with alveolar bone lysis, tooth displacement, and sinusal floor lysis. A 23-year-old pregnant woman with 23 weeks of amenorrhea was referred to the Department of Oral and Maxillofacial Surgery with a large maxillary mass and spontaneous bleeding, causing difficulty in speaking and swallowing. Due to the rapid development, the stage of pregnancy, and the need for a sure diagnosis of a benign lesion, a surgical excision was performed. After 1 month, the patient recovered from swallowing and speaking. Pregnancy epulis can be locally aggressive and involve alveolar bone. Biopsy allows to confirm the diagnosis. Surgery during pregnancy or birth waiting should be well ponderated in correlation with the size of the tumor and the delay to birth.

Access to dental care is still complex in 2022 for patients living with HIV despite the need for careful monitoring of pathologies of the oral mucosa. Results of a monocentric cross-sectional study in the Infectious Diseases Department of Clermont-Ferrand University Hospital.

OBJECTIVES: Describe the dental care pathway of people living with HIV (PLHIV) and their oral pathologies. MATERIALS AND METHODS: A monocentric cross-sectional study involving adult PLHIVs followed (October 2021/April 2022) in our department. Socio-demographic and medical data, course of dental care, and presence of pathologies of the oral mucosa were recorded. RESULTS: 112 PLHIV (71% men, 54 ± 14 years) were included. Of the 112, 96% had already consulted a dentist, and 78% had a referring dentist; 73% had disclosed their seropositivity; for 84%, the visit proceeded normally, 7% refused treatment; for 8%, the dentist was not comfortable, and for 4% the dentist's attitude became negative; 21% of the PLHIV had already encountered difficulties in finding a dentist including 37% because of their viral status. Among the oral pathologies listed, 23 lesions were identified: 15 (65%) were unrelated to HIV, 4 (17%) were classified stages B/C (1 Kaposi's sarcoma, 1 oral villous leukoplakia, 2 chronic candidiasis), and 4 (17%) were lesions with evolution specifically due to HIV (2 inhomogeneous leukoplakias, 1 cancer, 1 verrucous papilloma). CONCLUSION: Although 78% of the PLHIV included had a referring dentist, discrimination by dentists toward PLHIV still persists (16% of the PLHIV concerned). CLINICAL RELEVANCE: 27% of participants did not feel ready to disclose their infection. The resulting lack of follow-up is also a loss of opportunity because while most of the small number of oral lesions diagnosed in this population are related to age or comorbidities, some are serious and need to be identified.

Poor dental condition is a factor of imbalance of the nutritional status at the outset of management of head and neck cancer.

OBJECTIVES: To determine whether deterioration of dental condition at the outset of management of head and neck cancer (HNC) is a nutritional risk and whether social deprivation is a cause of the poor dental condition observed in HNC patients. MATERIAL AND METHODS: A nutritional assessment form (NAF) and the Nutrition Risk Index (NRI) were used to standardize the nutritional status of 108 patients at the outset of management of HNC (2017-2019). The NAF includes assessment of weight loss over the past 3 months, the amount and difficulty of food intake, and the presence of digestive disorders. Dental condition was assessed by the decayed, filled, and missing teeth acopre (DFM) index and the masticatory coefficient (MC). Dental status and social deprivation were correlated with the EPICES score. RESULTS: A correlation was found between the extent of weight loss and dental condition. The MC was higher in absence of weight loss (46% vs. 27%, p = 0.03) and the DMF lower when weight loss was less than 5% (22.3 vs. 26.9 if > 5% loss of weight, p = 0.005). No correlation was found between dental status and nutritional status. Social deprivation was associated with a lower MC (26% vs. 50%, p < 0.001). CONCLUSION: Dental condition is a risk factor for weight loss at the outset of management of HNC but is not a determinant of nutritional status. Clinical relevance Dental condition is no longer considered simply as a source of potential complications after radiotherapy but also as an important factor for nutritional status.

Ectopic third mandibular molar: evaluation of surgical practices and meta-analysis.

OBJECTIVES: To identify the preferred surgical approach (intra- or extra-oral) to remove an ectopic third mandibular molar (ETMM) according on its location and presence of an associated cyst or cutaneous fistula, and to determine the indications for a graft or osteosynthesis. MATERIALS AND METHODS: A surgical practice questionnaire was distributed to oral and maxillo-facial surgeons attending a National Congress of the French Society of Stomatology, Maxillo-facial and Oral Surgery. A systematic review of the literature and meta-analysis was carried on Pubmed, Cochrane, Embase and ScienceDirect databases using the MeSH terms: "Ectopic teeth", "Third molar", "Mandibular". One hundred and forty-three surgeons answered the questionnaire and the meta-analysis included 66 articles. RESULTS: From the questionnaire, the preferred surgical approach was intra-oral except when the ETMM was in the condyle, when it was extra-oral (69.5%; p < 0.001). In the meta-analysis, an extra-oral approach was only indicated when a cutaneous fistula was present (90% vs. 35.9%; p = 0.002), irrespective of ETMM location. In the questionnaire and meta-analysis, the presence of a cyst did not change the approach (p < 0.05). The indications for a graft or osteosynthesis were a condylar location (p < 0.001), while a cutaneous fistula decreased the indication (p = 0.04) and a cyst (p = 0.009) was only associated with a graft. CONCLUSIONS: The preferential approach was intra-oral, except when the ETMM was condylar or a cutaneous fistula was present when an extra-oral approach was preferred. Osteosynthesis or a graft were more likely when the ETMM was in the condyle. CLINICAL RELEVANCE: This study will help to orientate surgeons vis-à-vis ETMM treatment.

Virtual Surgery Planning and Three-Dimensional Printing Template to Customize Bone Graft Toward Implant Insertion.

Premaxillary tooth loss and bone deficiency or atrophy often occur in facial trauma. Onlay bone graft and implants have so far been the best means of restoring function and esthetic appearance. Void space between the graft and the jaw bone, over projection and mucosal trauma can cause mucosal dehiscence, bone exposure, or resorption and can compromise implant survival. Virtual surgical planning using 3-dimensional printing technology has improved the efficiency of craniofacial surgery. The drawbacks of this technology are its cost and time-consuming preparation. However, the democratization of high-performance 3-dimensional printing and open-source software have enabled surgeons to master the procedure. The authors applied this innovative technology to customize bone graft for insertion of a premaxillary implant. It enabled us to custom-make the bone graft on the template and to perfectly embed the graft in the gap with a reduce operating time and a good osteointegration.

The relationship between resting arterial blood pressure and oral postsurgical pain.

OBJECTIVES: This prospective study examined the relationship between resting blood pressure (BP; primary outcome), demographic features of patients, anatomical characteristics of the extracted teeth, surgery variables (secondary outcomes), and acute postsurgical pain in patients undergoing tooth extraction. MATERIALS AND METHODS: Standardized surgery was performed under local anesthesia. A composite numerical index, referred to as "postoperative pain/analgesia score" (PPAS), was built out of two intermediate ones, indicating (i) the degree of spontaneous pain reported by the patient (postoperative pain score) and (ii) the amount of analgesic drug intake (postoperative analgesia score). RESULTS: A total of 293 patients with complete data sets were included in the analysis. Univariate analysis reveals that the intensity of postoperative pain is related to age, history of hypertension and previous oral surgery, number of extracted teeth, duration of surgery, and extraction of the third molar. On the other hand, there is no relationship with gender, anxiety, and operation duration. Multivariate analysis reveals that the intensity of acute postoperative pain is only associated with the location (upper/lower jaw, P = 0.004) and deepness of implantation of the extracted tooth (P < 0.0001), and mean resting BP (P = 0.031). CONCLUSIONS: This large prospective study shows that patients with high resting BP had a lower oral postsurgical pain than those with low resting BP. This suggests that high resting BP is a protective factor against oral postsurgical pain. CLINICAL RELEVANCE: The measurement of resting BP before surgery may be used in clinical practice to identify patients at risk of developing severe oral postsurgical pain.

After 4 years of survival, patients treated for an oral or oropharyngeal cancer have more neurosensorial disorders than chronic pain and a better quality of life.

PURPOSE: During follow-up, patients in remission after oral or oropharyngeal cancer are few to express pain, depression or anxiety, their chief complain are dry mouth and difficulties to chewing. The aim of the study is to estimate prevalence of pain, quality of life and their evolution over four years. METHODS: This prospective observational study included 21 patients between June and September 2017. Clinical examination, neurosensory examination and questionnaires (using visual analogic scale DN4, PCS-CF, HADS EORTC QLQ30 and H&N 35) were performed and a second time 4 years later. RESULTS: After 4 years, 17 patients could be reviewed. In 2017 as in 2021, two patients (11.8 %) experience neuropathic pain. In 2017, 14 (82.3 %) reported paresthesia or dysesthesia or hypo/anesthesia, none of them have provoked pain to a mechanical or thermal stimulus. In 2021, only 9 (53 %) still report those symptoms. Global analysis of the questionnaire QLQC30 reveals a significant increase quality of life of all 17 patients (p = 0.0003). For the two questionnaires QLQC30 and QLQ-H&N 35, dry mouth, sticky saliva, difficulties for eating and relation with food, are strong grievances which an absence of amelioration or a degradation. CONCLUSIONS: Neurosensory disturbance is a frequent symptom but pain concerns only 11.8 % of patients. Quality of life increase globally, yet difficulties concerning oral cavity functions endure. IMPLICATIONS FOR CANCER SURVIVORS: For remission patients, pain is an unfrequent situation unlike neurosensory disturbance. Support care improve life quality. In case of onset of pain, recurrence and osteoradionecrosis should be mentioned immediately.

A proof-of-concept augmented reality system in oral and maxillofacial surgery.

BACKGROUND: The advent of digital medical imaging, medical image analysis and computer vision has opened the surgeon horizons with the possibility to add virtual information to the real operative field. For oral and maxillofacial surgeons, overlaying anatomical structures to protect (such as teeth, sinus floors, inferior and superior alveolar nerves) or to remove (such as cysts, tumours, impacted teeth) presents a real clinical interest. MATERIAL AND METHODS: Through this work, we propose a proof-of-concept markerless augmented reality system for oral and maxillofacial surgery, where a virtual scene is generated preoperatively and mixed with reality to reveal the location of hidden anatomical structures intraoperatively. We devised a computer software to process still video frames of the operating field and to display them on the operating room screens. RESULTS: Firstly, we give a description of the proposed system, where virtuality aligns with reality without artificial markers. The dental occlusion plan analysis and cusps detection allow us to initialise the alignment process. Secondly, we validate the feasibility with an experimental approach on a 3D printed jaw phantom and an ex-vivo pig jaw. Thirdly, we evaluate the potential clinical benefit on a patient. CONCLUSION: this proof-of-concept highlights the feasibility and the interest of augmented reality for hidden anatomical structures visualisation without artificial markers.

Dental Trauma Management in a Young Teenager through Endodontics and Implantology: A Case Report.

Endodontic treatment is often the first-line procedure to manage the immediate or long-term aftermath of dental trauma, particularly in cases of luxation or avulsion. Failure to manage trauma in the short or medium term leads to significant functional or aesthetic consequences, especially in the adolescence period. Under this specific conditions, endodontic treatment could provide a temporary solution by keeping teeth with poor prognosis on the arch while waiting for better anatomical conditions for implantology. This clinical case aimed to describe the management of a maxilla-facial dental trauma and the following consequences in a 10-year-old male patient. Clinical and radiological examination showed complete extrusive luxation of 11 and 21 and intrusive luxation of 12 and 22. Endodontic treatment of 11 and 21 was performed six months after the trauma. Two years later, the patient was referred to the endodontic department because pink spot lesions appeared on 12 and 22 due to cervical invasive resorptions (class III for 12 and class II for 22). Endodontic treatment of 12 and filling with resin composite of 22 were performed. During the following two years, complication management finally led to placement of four OBI® (Euroteknika, Sallanches, France)-type mini-implants after avulsion of all four maxillary incisors. Palliative endodontic treatment helped maintain the prosthetic space and the volume of supporting tissue needed for future implant placement. The interest of using delaying procedures (palliative endodontic treatments and mini-implants) was to allow the patient to complete growth. Managing early treatment failure of trauma in adolescents has to be pluridisciplinary and should take into account the evaluation of the treatment's difficulty, the prognosis of the endodontic treatment, the available bone volume and the pubertal growth stage.

Characteristics of pain in patients with pituitary adenomas: A cross-sectional study.

BACKGROUND: This study determines the prevalence and particularities of headache and pain with neuropathic characteristics (NC) in a large French group of patients with pituitary adenoma (PA). METHODS: Analysis of validated self-administered questionnaires, radiological characteristics and treatment strategies of PA was performed. RESULTS: Of the 221 sent questionnaires, 146 could be used for statistical analysis, 50% of which were completed by women. Among responders, 58.9% had pain: 30.1% migraine, 15.7% pain with NC and 13.1% other types of pain. Migraine was more common in patients with PA than in the general population (30.1% vs. 21.3%, p = .010) and attacks received appropriate treatment for less than 20% of these patients. Furthermore, the prevalence of chronic migraine was much higher than in the general population (6.8% vs. 2.2%, p = .003). Neuropathic pain was also more frequent in PA patients than in the general population (15.8% vs. 6.9%, p < .001). Neuropathic pain was most often located in the extremities and was frequently described as an 'electric shock', 'numbness', or 'pins-and-needles'. Multivariate analyses linked migraine to younger age, anxiety, pain with NC, and a visible tumour on MRI, regardless of its invasiveness or secretory nature. CONCLUSIONS: Migraine headaches and neuropathic pain are more frequent and disabling in PA patients than in the general population. Both types of pain are comorbid in PA patients and are poorly treated. Migraine is associated with the presence of a tumour. Thus, biological mechanisms of this relationship need to be characterized to design optimal treatments for these individuals. SIGNIFICANCE: Migraine headaches and neuropathic pain are more common in PA patients than in the general population and are generally poorly treated. A systematic screening for migraine should be done by physicians in daily practice to provide adequate therapeutics.

Five Predictors Affecting the Prognosis of Patients with Severe Odontogenic Infections.

Background: Dental cellulitis management is no longer a simple procedure, as more and more patients are needing long-time hospitalization, several surgeries and intensive care follow-up. This prospective study seeks to highlight criteria that can split patients with severe odontogenic infection into two groups: those with simple evolution and those for whom complex management is necessary. Methods: In this observational study, all patients considered with a severe odontogenic infection (which necessitated hospital admission, intravenous antibiotics and general anaesthesia) were enrolled between January 2004 and December 2014 from Clermont-Ferrand University Hospital (France). They were split into two groups: those who needed one surgical intervention with tooth extraction and collection drainage combined with probabilistic antibiotic to treat infection and those who need several surgeries, intensive care unit follow-up or tracheotomy to achieve healing. Results: 653 patients were included, of which 611 (94%) had one surgery, 42 (6%) had more than one surgery before healing. Penicillin allergy (p < 0.001), psychiatric disorders (p = 0.005), oropharyngeal oedema (p = 0.008), floor oedema (p = 0.004), fever (p = 0.04) and trismus (p = 0.018) on admission were the most relevant predictors of complex evolution. A conditional inference tree (CTREE) illustrated the association of prognostic factors and the need of multiple surgery. Conclusions: Besides clinical symptoms of severity, complications of severe odontogenic infection are predicted by measurables and objectives criteria as penicillin allergy, mandibular molar, C-reactive protein level, psychiatric disorders and alcohol abuse. Their specific association potentialize the risks. IRB number: CE-CIC-GREN-12-08.

Alendronate or Zoledronic acid do not impair wound healing after tooth extraction in postmenopausal women with osteoporosis.

BACKGROUND: Bisphosphonates (BPs) are widely used for the prevention or treatment of osteoporosis. One of the most serious complications associated with BPs is medication-related osteonecrosis of the jaw (MRONJ) but its incidence in patients with osteoporosis is very low ranging from 0.001-0.15%. A major predisposing factor for MRONJ is tooth extraction (TE). Controversies persist about the influence of current BP therapy regarding socket healing after TE. The aims of this study were to investigate prospectively, (i) alveolar bone healing, i.e., filling of the bony socket by new bone and (ii) mucosal healing, i.e., closure of the overlying mucosa, after TE in women receiving current BP therapy for the prevention or the treatment of postmenopausal osteoporosis. METHODS: Women with osteoporosis under current treatment with BPs (BP+ group) or other anti-osteoporotic medications (BP- group) undergoing single TE were included in this study. No antibiotic prophylaxis was prescribed solely for the BP therapy, but antibiotic treatment may have been required for local infectious conditions. Chlorohexidine mouthwashes were systematically prescribed in all study patients for one week after TE. New bone height (NBH) and rate of socket filling (RSF) were recorded using intraoral standardized radiographs one month and 3 months after TE (T30 and T90 respectively). The closure of the overlying mucosa was assessed by measuring the wound extent with an electronic caliper at 1 week and at 1 month after TE (T7 and T30 respectively). RESULTS: At T30, NBH was not statistically different between the BP+ and BP- groups (p = .76). At T90, more than a two-fold in NBH increase was recorded for both groups with no statistically significant difference between them (p = .76). At T30 and T90, RSF was similar in both groups (p = .58 and p = .32 respectively). More than a two-fold RSF increase was founded between T30 and T90 in both groups. No demographic or BPs-related factors were correlated with the RSF at T90. At T7, the mucosa wound extent was reduced by more than two-fold with no statistically significant difference between both groups (p = .80). At this time, mucosa healing was achieved in 11.9% of the BP+ group and 10% of the BP- group (p = .99). At T30, mucosal healing was achieved in all patients but two, and at T90 it was achieved in all patients. CONCLUSION: This study provides new insights into bone and mucosal healing in patients with osteoporosis taking BPs after TE. In this population, TE can be managed successfully with an appropriate surgical protocol and without discontinuation of BP treatment.

Assessment of oro-dental manifestations in a series of acromegalic patients, the AcroDent study.

OBJECTIVE: The dental and periodontal impact of GH/IGF-1 hypersecretion has been poorly investigated until now. Our aim is to precisely describe the oro-dental state of acromegalic patients and to study the impact of GH/IGF-1 hypersecretion on patients' reported oral health-related quality of life (OHRQoL). METHODS: After collecting characteristics of their disease, acromegalic patients answered the GOHAI questionnaire assessing their OHRQoL, the AcroQoL questionnaire and then benefited from a complete stomatological and radiological examination (orthopantomogram systematically, retro-alveolar radiography or Cone Beam CT if necessary). RESULTS: In total, 29 patients aged 59.1 ± 16.0 years were included. The average DMFT index (sum of Decayed, Missing and Filled Teeth per patient) was 19.0 ± 7.8. 16/29 patients had a gingivitis and 18/29 a mild to moderate chronic periodontitis, but no case of severe chronic periodontitis was found, probably because the frequency of a protective thick gingival biotype was increased (9/29). No case of generalized gingival hypertrophy or diffuse hypercementosis was observed. According to the Add-GOHAI score, only 8/26 patients had a satisfactory OHRQoL. This parameter was correlated to the acromegaly-specific quality of life according to the AcroQoL score. Interestingly, 11/29 patients had bulky oral bony outgrowths (OBO), such as large maxillary or mandibular tori and multiple vestibular exostosis. CONCLUSIONS: The unsatisfactory OHRQoL reported by acromegalic patients contrasts with a rather good objective oro-dental state and annual oral examination seems relevant in this population. Finally, we report that huge OBO could be helpful signposts for the diagnosis of acromegaly.

Impact of sympathetic activation on pain threshold in human subjects.

This study examined the effect of the sympathetic activation with the head-up tilt test (HUT) on electrocutaneous pain in 56 young normotensive volunteers. Systolic arterial blood pressure (SAP), diastolic arterial blood pressure (DAP), heart rate (HR), sensory and pain thresholds to electrocutaneous stimulation were measured 30s before (in supine position), during (at 10s, 90s, 3min and 5min) and 10min after HUT (in supine position). No relationship was found between resting BP and pain perception. HUT significantly increased DAP and HR, but did not change SAP. During HUT, both sensory and pain electrocutaneous thresholds were significantly increased, indicating reduced nociception. While changes in HR and changes in sensory threshold were correlated, no other correlation could be found between hemodynamic changes (DAP or HR) and changes in sensory and pain threshold. These results suggest that the mechanisms underlying the sympathetic adaptation to HUT and HUT-induced analgesia are different.

The nitric oxide donor, isosorbide dinitrate, induces a cephalic cutaneous hypersensitivity, associated with sensitization of the medullary dorsal horn.

Nitric oxide donors are known to produce headache in healthy as well as migraine subjects, and to induce extracephalic cutaneous hypersensitivity in rodents. However, little is known on the effect of nitric oxide donors on cephalic cutaneous sensitivity. Combining behavioral, immunohistochemical, and in vivo electrophysiological approaches, this study investigated the effect of systemic administration of the nitric oxide donor, isosorbide dinitrate (ISDN), on cephalic and extracephalic cutaneous sensitivity and on neuronal activation within the medullary dorsal horn (MDH) in the rat. Systemic administration of ISDN increased selectively the first phase and interphase of the facial formalin test, but had no effect on the hindpaw formalin one. Monitoring neuronal activity within the MDH with phospho-ERK1/2 immunoreactivity revealed that ISDN alone did not activate MDH neurons, but significantly increased the number of formalin-evoked phospho-ERK1/2-immunoreactive cells in the ipsilateral, but not contralateral, MDH. Using in vivo electrophysiological unit recordings, we show that ISDN administration never affected the spontaneous activity of trigeminal wide dynamic range neurons, but, facilitated C-fiber-evoked responses in half the neurons tested. This research demonstrates that a nitric oxide donor, isosorbide dinitrate, induces selectively cephalic hyperalgesia that arises as a consequence of central sensitization in pain pathways that subserve meningeal nociception. This model better mimics the clinical condition and offers another possibility of studying the role of nitric oxide donor in the physiopathology of headache.

Cancer pain is not necessarily correlated with spinal overexpression of reactive glia markers.

Bone cancer pain is a common and disruptive symptom in cancer patients. In cancer pain animal models, massive reactive astrogliosis in the dorsal horn of the spinal cord has been reported. Because astrocytes may behave as driving partners for pathological pain, we investigated the temporal development of pain behavior and reactive astrogliosis in a rat bone cancer pain model induced by injecting MRMT-1 rat mammary gland carcinoma cells into the tibia. Along with the development of bone lesions, a gradual mechanical and thermal allodynia and hyperalgesia as well as a reduced use of the affected limb developed in bone cancer-bearing animals, but not in sham-treated animals. Dorsal horn Fos expression after nonpainful palpation of the injected limb was also increased in bone cancer-bearing animals. However, at any time during the evolution of tumor, there was no increase in glial fibrillary acidic protein (GFAP) immunoreactivity in the dorsal horn. Further analysis at 21days after injection of the tumor showed no increase in GFAP and interleukin (IL) 1ß transcripts, number of superficial dorsal horn S100ß protein immunoreactive astrocytes, or immunoreactivity for microglial markers (OX-42 and Iba-1). In contrast, all these parameters were increased in the dorsal horn of rats 2weeks after sciatic nerve ligation. This suggests that in some cases, bone cancer pain may not be correlated with spinal overexpression of reactive glia markers, whereas neuropathic pain is. Glia may thus play different roles in the development and maintenance of chronic pain in these 2 situations.

Cardiovascular influences on conditioned pain modulation.

Conditioned pain modulation (CPM) (ie, diffuse noxious inhibitory controls) is characterized by reduced perception of pain caused by intense pain in a remote body area. The conditioning stimuli used to trigger CPM causes pain, but also important cardiovascular responses. Higher blood pressure has been associated with reduced pain sensitivity. Descending pain inhibitory mechanisms such as CPM could be involved in this relationship. We investigated the associations between CPM and cardiovascular responses during the cold-pressor test (CPT). Heat pain threshold and tolerance were evaluated in 26 (13 men, 13 women) healthy subjects. CPM was evaluated by comparing pain intensity produced by a 120-second heat stimulation before and after a CPT (5 minutes, 7°C). Heart rate, blood pressure, and baroreflex sensitivity were monitored at rest and during CPT to evaluate cardiovascular responses. We observed a positive relationship between resting blood pressure and heat pain tolerance. The CPT caused important heart rate and blood pressure increases. CPT also reduced pain intensity during the subsequent heat pain-stimulus, indicating effective CPM. A significant positive association was observed between CPM magnitude and the increase in blood pressure during the CPT. These results show that resting blood pressure values are related to acute pain tolerance, while descending pain inhibition is associated with increases in blood pressure. The rise in blood pressure caused by the conditioning stimulus is an important factor predicting the extent of endogenous pain inhibition in healthy subjects.

Representation of dynamic mechanical allodynia in the ventral medial prefrontal cortex of trigeminal neuropathic rats.

Trigeminal neuropathic pain is due to lesion or dysfunction of the nervous system. Dynamic mechanical allodynia is a widespread symptom of neuropathic pain for which mechanisms are still poorly understood. Recent studies demonstrate that forebrain neurons, including neurons in the medial prefrontal cortex (mPFC) are important for the perception of acute and chronic pain. Using the phosphorylation of the extracellular-signal regulated kinase (pERK-1/2) as an anatomical marker of neuronal activation, the present study investigated how dynamic mechanical allodynia is processed in the rat ventral mPFC (prelimbic and infralimbic cortex) after chronic constriction injury to the infraorbital nerve (IoN-CCI). Two weeks after unilateral IoN-CCI, rats showed a dramatic bilateral trigeminal dynamic mechanical allodynia. Light, moving stroking of the infraorbital skin resulted in strong, bilateral upregulation of pERK-1/2 in the ventral mPFC of IoN-CCI animals. pERK-1/2 was located in neuronal cells only. Stimulus-evoked pERK-1/2 immunopositive cell bodies displayed a rostrocaudal gradient and layer-selective distribution in the ventral mPFC, being predominant in the rostral ventral mPFC and in layers II-III and V-VI of the ventral mPFC. In layers II-III, intense pERK-1/2 also extended into distal dendrites, up to layer I. These results demonstrate that trigeminal nerve injury induces a significant alteration in the ventral mPFC processing of tactile stimuli and suggest that ERK phosphorylation contributes to the mechanisms underlying abnormal pain perception under this condition.