This study reviewed the recent progress in electrophysiological studies using electroencephalography (EEG), magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) on human pain perception. Following activity in the thalamus, a very weak activity is found in the primary somatosensory cortex (SI) contralateral to the stimulation. Thereafter, the bilateral secondary somatosensory cortex (SII) and bilateral insula are activated. In particular, the anterior part of the insula is thought to play an important role in pain perception. As a result, the bilateral anterior cingulate cortex (ACC) and bilateral amygdala, which are thought to be related to emotional aspects of pain perception, are also activated.
There are two kinds of pain, the first pain (sharp pain) ascending through A-delta fibers and the second pain ascending through the unmyelinated fibers. In an event-related fMRI study, the stimulation of both C and A-delta nociceptors activated the bilateral thalamus, bilateral secondary somatosensory cortex (SII), right (ipsilateral) middle insula, and bilateral Brodmann's area (BA) 24/32, with the majority of activity found in the posterior portion of the anterior cingulate cortex (pACC). However, the magnitude of activity in the right (ipsilateral) BA32/8/6, including the dorsal parts of the anterior portion of the ACC (aACC) and pre-supplementary motor area (pre-SMA) and the bilateral anterior insula were significantly stronger following the stimulation of C nociceptors than A-delta nociceptors. Therefore, the activation of C nociceptors, related to the second pain, evokes different brain processing apart from the A-delta nociceptors, related to the first pain, probably due to differences in the emotional and motivational aspects of either type of pain, which are mainly related to the aACC, pre-SMA and anterior insula.

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Purpose: A variety of changes occur in the peripheral and central nervous systems with advancing age. The neuronal network in pain pathways is also affected by age. However, the nature of the change in the central pain pathways is still unclear. This study was designed to understand the characteristics of changes in the mechanisms of nociception with advancing age.
Methods: The physiological properties of aged (29-34 mo old) and adult (7-13 mo old) Fisher 344/DuCrj rats were used for the present study. Data from the nocifensive behavior test, electrophysiological and immunohistochemical experiments were analyzed in detail.
Results: The paw withdrawal latency and licking occurrence were significantly lower in the aged rats than those of the adult rats following heat stimulation of the hind paw. Aged rats exhibited a significantly lower mechanical paw withdrawal threshold before inflammation after complete Freund's adjuvant (CFA) injection. The changes of foot temperature and thickness after CFA injection were greater and lasted longer in aged than in comparison to adult rats. The responses of single dorsal horn nociceptive neurons to noxious stimulation and the spontaneous activity were significantly higher in the aged in comparison to adult rats. A reversible local anesthetic block of the descending pathways resulted in a dramatic increase in the neuronal activity in adult rats but had little effect in aged rats. A significant loss of serotoninergic and noradrenergic fibers was reported in the spinal dorsal horn of the aged rats. Furthermore, pretreatment with naloxone i.v. injection significantly increased the number of capsaicin-induced pERK-LI cells in the trigeminal spinal subnucleus caudalis in adult rats but not in aged rats following subcutaneous capsaicin injection into the whisker pad region.
Conclusions: The present findings suggest that the descending pain modulation system becomes impaired with advancing age, thus resulting in the abnormal pain sensation in aged rats.

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Purpose: Although orofacial pain is usually classified into somatic pain, neuropathic pain and psychogenic pain, it should be divided into general medical conditions (Axis I) and mental disorders with somatization (Axis II). A typical axis II disorder in orofacial pain is a pain disorder. Most atypical odontalgia, idiopathic glossalgia and refractory temporomandibular joint dysfunction may be diagnosed as a pain disorder. This paper outlines the diagnosis and treatment of pain disorders.
Study selection: The diagnosis of pain disorders, were based on the Diagnostic Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) edited by the American Psychiatric Association. The treatment of pain disorder was based on the results of randomized controlled trials, results from a previously reported paper and experience in daily clinical settings.
Results: Pain disorders are appropriately diagnosed based on the DSM-IV criteria. It is important not to perform an irreversible or invasive procedure for the treatment of a pain disorder. Prescription of an antidepressant including amitriptyline and a psycho-social approach including cognitive-behavioral therapy are also effective. There is sufficient evidence to support pharmacotherapy with antidepressants.
Conclusions: It is recommended that pain disorders should be treated with antidepressants including amitriptyline.

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The treatment of temporomandibular disorders (TMD) may often include complicated problems such as chronic pain, occlusal parasthesia, unidentified complaints and psychosomatic disorders. Although most dentists have a consultation and treat TMD patient by themselves, the author works with a psychiatrist in these complicate conditions. The cooperative consultation and treatment with a psychiatrist is called “liaison” and is its importance is gradually being realized. This paper explains the liaison management in cases of TMD with chronic pain, occlusal parasthesia and other unidentified complaints.
The patients are classified into the following four categories: A. There is no objective finding which explains the subjective symptoms, B. The relationship between the objective findings and subjective symptoms is weak, C. Both psychic symptoms and somatic diseases are present, and D. Psychosomatic disorder is obvious. The management was done following this classification.
Managements : In cases of A and B since the possibility of the cause being dental or medical somatic diseases is low, the patients' clinical conditions are explained, followed by conservative treatment, rather than actively providing surgical treatment. If subjective symptoms such as insomnia and depression are found, then the patients are suggested to consult a psychiatrist for collaboration treatment. In the comorbid case C, both dental diseases and mental disorders are treated in parallel. It is important to maintain good communication with psychiatrist with these cases. In the case D, psychosomatic disorders in a narrow sense, the patients must be aware of their stresses, and understand the relationship between mind and body and be encouraged to ease their mental burdens. In addition, they should be introduced to relaxation methods, such as autogenic training and progressive muscle relaxation method and, if necessary, combined drug therapy (antianxiety drug, antidepressants, etc). Multiple evaluation and management is important for TMD patients with complicated conditions.

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Objective: Tic douloureux is classitied into three types according to its clinical symptoms. This study reports the efficacy of microvascular decompression on the conditions defined according to the International Classification of Headache Disorders (ICHD-II).
Selection of the Study: Tic douloureux is classified into three types according to its clinical symptoms: Class I: Typical classical trigeminal neuralgia: paroxysmal (lasting for several seconds), typical, with sharp, fulminant pain (but without lingering pain); a recognizable trigger zone; a condition that responds to treatment with Tegretol. Class II: Atypical tic; some with sustained pain; the area associated with pain is near the parietal region, often exhibiting an atypical distribution (such as behind the eye). There may be insensitive areas. Class III: Atypical facial pain syndrome: sustained dull pain dominates the symptoms; the condition may be manifested by such conditions as a cluster headache, maxillary cancer, empyema, Sluder syndrome and post-radiotherapy trigeminal neuralgia (following the application of a gamma knife). The patients were stratified according to the classification method noted above. With special reference to the 1,910 patients with tic douloureux who were treated with microvascular decompression based on the method adapted by Dr. Takanori Fukushima and on previous cases at this hospital, the efficacy of this procedure in the field of neurosurgery, in particular on tic douloureux, was reported. The authors hope that the results will shed some light on the management of pain in the area of the trigeminal nerve and the selection of therapeutic procedures in future.
Results: Microvascular decompression was applied to Class I patients (87% of the patient group). A complete recovery was noted in 96%, while vascular compression was no longer observed in 7%. The condition returned in 6 months to one year in 4%, that failed to achieve a complete recovery. Class II conditions were found in 13%. The complete recovery rate was 70%, while 30% suffered recurrences without vascular compression or insufficient compression (mostly venous compression). Even when there was no vascular compression, the trigeminal nerve was frequently kinked; therefore the arachnoid membrane was detached from the trigeminal nerve to untwist the latter during surgery and a steroid was applied to the region. Only 1% of the patients were designated as Class III. Their pathophysiology differed fundamentally from the others. For those patients, surgery was contraindicated and no recovery was noted. The 3.0 telsa sagittal and coronal MRI images were found to be an effective mode of imaging to examine the status of vascular compression around the nerve.
Conclusion: For Class I of tic douloureux, microvascular decompression is the first therapeutic choice. The results were highly satisfactory. If the patient is elderly and anesthesia is not possible, then stereotactic radiosurgery (therapy using a cyber knife) should be considered. For Class II, the clinical symptoms should be examined carefully and other therapeutic modalities should be taken into consideration. If neurovascular decompression is selected, the procedure must be conducted at facilities with ample experience with this procedure. Microvascular decompression must be avoided for Class III. A surgical cure cannot be expected from a sustained dull headache that is experienced after treatment with a gamma knife.

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Purpose: To investigate analgesic effect of artificial dermis for repair of oral mucosal defects and to study the factors associated with the effect.
Methods: Sixty-one patients who underwent repair of oral mucosal defects using artificial dermis participated in this study. The use of analgesic drugs were recorded for assessment of the analgesic effect. To study the factors related to the analgesic effect, the gender, age, depth of the wound, use of fixation and size of the graft were compared. A logistic regression analysis was used to analyze the correlation between the analgesic effect and the conditions of the patients.
Results: A total of 31% of patients took analgesic drugs on the day after surgery. There was a significant correlation (p=.003) between the analgesic effect and the minimum diameter of the artificial dermis. The minimum diameter of the graft ranged from 5 to 40 mm, with a median of 15 mm in patients that experienced an analgesic effect. The diameter ranged from 10 to 40 mm, with a median of 30 mm in patients without analgesic effect.
Conclusions: The repair of oral mucosal defects using artificial dermis is associated with an analgesic effect in many patients. Reducing the minimum diameter of the artificial dermis may therefore contribute to a decrease in the postoperative pain.

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Patients: Case report 1: A 51-year-old male presented with pain in his right mandible. According to the patient, it was provoked by the cold wind on a railroad station platform on the way to work. After examining the patient, there was no evidence of any such causality. Eventually, the orofacial pain was suspected to be of cardiac origin. Consequently, the patient was referred to the department of cardiology and thus diagnosed to have angina pectoris.
Case report 2: A 60-year-old male was referred with complaints of bilateral pain in the temporomandibular joints and masseter muscles. His symptoms indicated that he was suffering from trismus and had difficulty eating. Although there was tenderness of the bilateral masseter, it was not possible to identify the cause of the pain. The patient also complained of chest discomfort, thus the orofacial pain was suspected to be of cardiac origin and the patient was referred to the department of cardiology, where the patient was diagnosed with myocardial infarction.
Discussion: It is therefore important to consider the diagnosis of cardiac orofacial pain when there is no evidence of dental findings. This possibility should be taken into account regardless of whether or not the patient has any chest pains.
It is useful to use a structured questionnaire of pain to detect non-odontogenic orofacial pain in order to make a differential diagnosis in such cases.
Conclusions: Acute coronary syndrome is a medical emergency. Timely diagnostic and therapeutic interventions are known to improve the patients' survival. When the patient has some pathognomonic associated symptoms without chest pain and a clinician suspects that an orofacial pain is of cardiac origin, the patient should immediately be referred for appropriate medical care.

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Patients: Two patients experienced chronic burning pain on mucosa over several years. The pain was around a tooth and constant, local provocation of the tooth or mucosa was not consistently associated with the pain, no clinical radiographic signs of pathology were present in the tooth, related dental therapies failed to resolve the pain and the response to local anesthesia was equivocal. As a result, these patients probably had continuous trigeminal neuropathic pain. Several medications were administered, but the relief the pain was unsatisfactory and mucosal oppression on the mucosa showed some pain relief.
Discussion: This is the first report to show that mucosal oppression relieved pain in trigeminal neuropathic pain cases. Mucosal oppression stimulates the Aβ fibers in the peripheral nerve, while also closing the gate for pain conducting C fibers.

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