Stellate ganglion block as an early intervention in sympathetically maintained headache and orofacial pain caused by temporal arteritis.

INTRODUCTION: We report a case of temporal arteritis with a sympathetic component in the orofacial region, which responded to stellate ganglion blocks (SGBs). CASE: An 81-year-old woman with limited mouth opening and pain upon chewing was referred to the Orofacial Pain Clinic at Nihon University Dental Hospital. The patient also presented with blurred vision and a burning sensation on the right side of her face. On clinical examination, the temporal artery was tender to palpation, and there was increased sensitivity in the temporal region bilaterally. The patient reported jaw pain and limited mouth opening. Laboratory examination showed elevations in erythrocyte sedimentation rate and C-reactive protein. The burning sensation was due to a sympathetic component, and SGBs substantially reduced both the burning sensation and right temporal pain. Blocking the sympathetic chain on the ipsilateral side also improved jaw movement. The patient was referred to a rheumatologist, after which she was admitted to hospital with a tentative diagnosis of temporal arteritis. Treatment with oral prednisone 30 mg daily was initiated, and the dose was tapered as her symptoms resolved. DISCUSSION: The reason for the gradual pain relief after SGB is unclear, but we believe it was effective for ischemia in temporal arteritis because it led to dilation of affected arteries or suppression of inflammation/edema of the vascular wall. CONCLUSION: This case demonstrates that SGB may relieve pain related to temporal arteritis and sympathetically maintained headache and orofacial pain by reducing noxious stimulation peripherally and decreasing central pain transmission centrally.

Hemicrania continua in a patient with concomitant dental disease.

BACKGROUND: There are nonodontogenic headache disorders that mimic dental pain. One such headache disorder is hemicrania continua (HC). HC is a primary headache syndrome characterized by a continuous, unilateral headache that is completely responsive to indomethacin. Patients may have signs and symptoms that the dentist should differentiate from odontogenic pain and temporomandibular disorders. These symptoms can make the diagnostic process a challenge for dentists if patients' pain has multiple causes. Dentists, thus, must have thorough knowledge of odontogenic and nonodontogenic causes of pain so they can make accurate diagnoses and prepare treatment plans. CASE DESCRIPTION: The authors describe the case of a 41-year-old woman with a six-year history of continuous headaches and a one-year history of temporomandibular dysfunction and odontogenic pain. She sought treatment from a number of dentists and received a diagnosis of right-side facial pain and headache on the basis of the results of clinical and radiologic examinations, which was followed by dental treatment. She did not experience any pain relief. Additional results of our examination led to a diagnosis of HC. CLINICAL IMPLICATIONS: Dentists must consider headache disorders in patients who have continuous headaches after undergoing dental treatment for odontogenic pain.

A possible case of complex regional pain syndrome in the orofacial region.

OBJECTIVE: To present a case of complex regional pain syndrome (CRPS) type II with sympathetic dysfunction and trophic changes in the orofacial region, which was partially responsive to intravenous ketamine. PATIENT: The patient was a 68-year-old man who suffered from inveterate pain with trophic changes of the right face and tongue and vasomotor dysfunction on the right side of the face after ipsilateral trigeminal nerve block. Allodynia and hyperalgesia were observed on the affected side of the face. Pain initially improved after sympathetic nerve block, but similar pain returned that was unresponsive to the same procedure. Repeated intravenous administration of low-dose ketamine preceded by intravenous midazolam alleviated the pain, but trophic changes of the tongue persisted. DISCUSSION: CRPS in the orofacial region has not been clearly defined and has been infrequently documented. Clinical findings in this patient met the criteria of the International Association for the Study of Pain's and Harden's diagnostic criteria for CRPS. The reason for gradual pain relief after induction of intravenous ketamine therapy was unclear, but the fact that only ketamine and not other various pain medicines or procedures alleviated the pain is important to note. CONCLUSION: Distinct cases of CRPS involving the orofacial region are rare. Thorough observations and documentation of signs and symptoms may lead to future standardization of diagnostic criteria and treatment strategies for this disorder.

Trigeminal neuralgia due to vertebrobasilar dolichoectasia: three case reports.

We report here 3 cases of trigeminal neuralgia (TN) due to vertebrobasilar dolichoectasia (VBD) and discuss the clinician's role in such cases. All cases presented at our clinic with paroxysmal, electric shock-like pain over their maxillary or mandibular gingiva. To confirm a diagnosis of TN, magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) were performed, and contact of the trigeminal nerve with a tortuous vertebrobasilar artery (VBA) was detected. Patients were informed about the therapeutic algorithm of TN before starting treatment. When medication became ineffective, the patients were referred to a neurosurgeon, and microvascular decompression (MVD) was consequently performed in 1 patient and radiofrequency thermocoagulation (RFTC) in the other 2 cases. VBD is associated with the risk of serious complications during follow-up and some limitations regarding second-line treatment. Dentists have a significant role in controlling orofacial pain and must be aware of this specific etiopathology of TN.

Topical capsaicin application causes cold hypersensitivity in awake monkeys.

Recent animal studies have demonstrated that many trigeminal ganglion neurons co-express TRPV1 and TRPA1 receptors following peripheral inflammation. In the present study, we examined whether cold receptors were sensitized by capsaicin in awake monkeys. Two monkeys were trained to detect a change in cold stimulus temperature (30 degrees C to 0.5, 1.0, 1.5 or 2.0 degrees C) applied to the facial skin. A total of 589 trials were studied, and the number of escape and hold-through trials and detection latency were measured. The number of escape trials was increased after capsaicin treatment, whereas that of hold-through trials was decreased. Detection latency was significantly decreased after capsaicin treatment. The present findings suggest that topical application of capsaicin to the facial skin induces reversible hypersensitivity to a facial cold stimulus in behaving monkeys.

Frequency-dependent ERK phosphorylation in spinal neurons by electric stimulation of the sciatic nerve and the role in electrophysiological activity.

The phosphorylation of extracellular signal-regulated kinase (pERK) in DRG and dorsal horn neurons is induced by the C-fiber electrical stimulation to the peripheral nerve. The present study was designed to investigate the expression and modulation of pERK in the rat dorsal horn neurons produced by repetitive electrical stimulation, and its involvement in the electrophysiological activity of dorsal horn neurons. Electrical stimulation of C-fiber intensity at different frequencies was applied to the sciatic nerve; the stimuli-induced pERK expression and the activity in dorsal horn neurons were studied by immunohistochemistry and extracellular recording, respectively. Electrical stimulation of C-fibers (3 mA) induced pERK expression in dorsal horn neurons in a frequency-dependent manner, indicating that the frequency of electrical stimulation is an important factor which activates the intracellular signal pathway in the spinal cord. To demonstrate the underlying mechanism of this frequency-dependent pERK expression, an NMDA receptor antagonist, MK-801, and a voltage sensitive calcium channel antagonist, nifedipine, were administrated intrathecally before the stimulation. We found that high frequency (0.5 Hz and 10 Hz) but not low frequent (0.05 Hz) stimulus-evoked pERK was partially inhibited by MK-801. Both high and low frequency stimulus-evoked pERK were inhibited by the nifedipine treatment. The extracellular single unit activities were recorded from the laminae I-II and V of the L4-5 dorsal horn, and we found that blockage of the intracellular ERK signal suppressed the wind-up responses in a dose-dependent manner. In contrast, any change in the mechanically evoked responses was not observed following the administration of ERK inhibitor. These observations indicate that ERK activation plays an important role in the induction of the wind-up responses in dorsal horn nociceptive neurons.

Anterior cingulate cortical neuronal activity during perception of noxious thermal stimuli in monkeys.

It has been reported that the anterior cingulate cortex (ACC) has a variety of functions relating to pain as well as pain perception. However, the underlying mechanisms for those functions remain unclear. To elucidate the functional role of the ACC in pain perception and pain-related functions such as attention to pain and escape from pain, single neuronal activity was recorded from the ACC, and the behavioral correlates of this neuronal activity was studied. A total of 667 neurons were recorded from the ACC in awake behaving monkeys. Twenty-one had modulated activity during a heat-detection task. Eighteen of these increased their firing frequency following an increase in stimulus temperature, whereas three of them had decreased firing during heating of the face. Seventy-five percent of heat-evoked responses of heat-responsive ACC neurons were significantly depressed when monkeys detected the change in magnitude of illumination of a light presented on the front panel. The neuronal activity was significantly higher when monkeys escaped from a noxious heat stimulus than when the monkeys detected a small change in temperature (T2) above a larger initial shift (T1). No relationship between firing frequency and detection latency of the T2 stimulation was observed. These findings suggest that ACC nociceptive neurons are involved in attention to pain and escape from pain but not in the sensory discriminative aspect of pain.

Effect of chronic inflammation on dorsal horn nociceptive neurons in aged rats.

To elucidate the effect of chronic inflammation on spinal nociceptive neurons in the elderly, we compared nocifensive behavior, peripheral inflammatory responses, and spinal dorsal horn neuronal activities between the aged (29-34 mo) and adult (7-12 mo) male rats after injection of complete Freund's adjuvant (CFA) into the hind paw. Aged rats exhibited a significantly lower mechanical paw withdrawal threshold before inflammation. However, after CFA injection mechanical allodynia developed in both adult and aged rats after CFA injection. The changes of foot temperature and thickness after CFA injection were greater and lasted longer in aged than in adult rats. Sets of 124 wide dynamic range (WDR) neurons (aged: 59, adult: 65) and 26 nociceptive specific (NS) neurons (aged: 13, adult: 13) were recorded from the lumber spinal dorsal horn. NS neurons from the inflamed adult rats showed significantly higher responses to noxious mechanical stimulation than those in aged rats, whereas WDR neurons from inflamed adult and aged rats were similar. Background activity of WDR neurons from the adult rats increased after CFA, whereas WDR neurons of aged rats and NS neurons from either group were not. The afterdischarge followed by noxious mechanical stimulation was significantly greater for WDR neurons in both adult and aged rats, whereas no significant differences were observed in NS neurons. Two days after CFA injection, Fos expression increased similarly in aged and adult rats. Thus the aged rats showed enhanced peripheral inflammatory responses to CFA injection with only a slight change in dorsal horn neuronal activity. Together with our previous finding that nociceptive neurons in aged rats exhibit hyperexcitability, these results suggest that the dorsal horn nociceptive system becomes sensitized with advancing age and its excitability cannot be further increased by inflammation.