Differential gene expression in trigeminal ganglia of male and female rats following chronic constriction of the infraorbital nerve

BACKGROUND

The mechanisms underlying sex-based differences in pain and analgesia are poorly understood. In this study, we investigated gene expression changes in trigeminal ganglia (TG) of male and female rats exposed to infraorbital nerve chronic constriction injury (IoN-CCI).

METHODS

Somatosensory assessments were performed prior to IoN-CCI and at selected time points postsurgery. Selected gene expression changes were examined with real-time quantitative polymerase chain reaction (RT-PCR) in ipsilateral TG at 21 days postsurgery.

RESULTS

Rats exposed to IoN-CCI developed significant mechanical allodynia and hyperalgesia on days 19 and 21 postsurgery. During this period, females developed significantly more allodynia but not hyperalgesia compared to males. At 21 days postsurgery, expression levels of 44 of the 84 investigated pain-related genes in ipsilateral TG were significantly regulated relative to naïve rats in either sex. Csf1 and Cx3cr1 were up-regulated in both sexes, but the magnitude of regulation was significantly higher in females (p = 0.02 and p = 0.001, respectively). Htr1a and Scn9a were down-regulated in both sexes, but the down-regulation was significantly more pronounced in males (p = 0.04 and p = 0.02, respectively). Additionally, Cck, Il1a, Pla2g1b and Tnf genes were significantly regulated in females but not in males, and Chrna4 gene was significantly down-regulated in males but not in females.

CONCLUSIONS

Our findings suggest sex-dependent gene regulation in response to nerve injury, which may contribute to sex dimorphism of trigeminal neuropathic pain. Further studies are needed to establish gene expression changes over time and correlate these with hormonal and other physiological parameters in male and female.

SIGNIFICANCE

We present novel sex-specific transcriptional regulation in trigeminal ganglia that may contribute to male-/female-based differences in trigeminal neuropathic pain. These findings are expected to open new research horizons, particularly in male versus female targeted therapeutic regimens.

Differential gene expression in trigeminal ganglia of male and female rats following chronic constriction of the infraorbital nerve

BACKGROUND

The mechanisms underlying sex-based differences in pain and analgesia are poorly understood. In this study, we investigated gene expression changes in trigeminal ganglia (TG) of male and female rats exposed to infraorbital nerve chronic constriction injury (IoN-CCI).

METHODS

Somatosensory assessments were performed prior to IoN-CCI and at selected time points postsurgery. Selected gene expression changes were examined with real-time quantitative polymerase chain reaction (RT-PCR) in ipsilateral TG at 21 days postsurgery.

RESULTS

Rats exposed to IoN-CCI developed significant mechanical allodynia and hyperalgesia on days 19 and 21 postsurgery. During this period, females developed significantly more allodynia but not hyperalgesia compared to males. At 21 days postsurgery, expression levels of 44 of the 84 investigated pain-related genes in ipsilateral TG were significantly regulated relative to naïve rats in either sex. Csf1 and Cx3cr1 were up-regulated in both sexes, but the magnitude of regulation was significantly higher in females (p = 0.02 and p = 0.001, respectively). Htr1a and Scn9a were down-regulated in both sexes, but the down-regulation was significantly more pronounced in males (p = 0.04 and p = 0.02, respectively). Additionally, Cck, Il1a, Pla2g1b and Tnf genes were significantly regulated in females but not in males, and Chrna4 gene was significantly down-regulated in males but not in females.

CONCLUSIONS

Our findings suggest sex-dependent gene regulation in response to nerve injury, which may contribute to sex dimorphism of trigeminal neuropathic pain. Further studies are needed to establish gene expression changes over time and correlate these with hormonal and other physiological parameters in male and female.

SIGNIFICANCE

We present novel sex-specific transcriptional regulation in trigeminal ganglia that may contribute to male-/female-based differences in trigeminal neuropathic pain. These findings are expected to open new research horizons, particularly in male versus female targeted therapeutic regimens.

Orofacial Pain in Cancer: Part I—Mechanisms

The mechanisms involved, and possible treatment targets, in orofacial pain due to cancer are poorly understood. The aim of the first of this two-part series is to review the involved pathophysiological mechanisms and explore their possible roles in the orofacial region. However, there is a lack of relevant research in the trigeminal region, and we have therefore applied data accumulated from experiments on cancer pain mechanisms in rodent spinal models. In the second part, we review the clinical presentation of cancer-associated orofacial pain at various stages: initial diagnosis, during therapy (chemo-, radiotherapy, surgery), and in the post-therapy period. In the present article, we provide a brief outline of trigeminal functional neuro-anatomy and pain-modulatory pathways. Tissue destruction by invasive tumors (or metastases) induces inflammation and nerve damage, with attendant acute pain. In some cases, chronic pain, involving inflammatory and neuropathic mechanisms, may ensue. Distant, painful effects of tumors include paraneoplastic neuropathic syndromes and effects secondary to the release of factors by the tumor (growth factors, cytokines, and enzymes). Additionally, pain is frequent in cancer management protocols (surgery, chemotherapy, and radiotherapy). Understanding the mechanisms involved in cancer-related orofacial pain will enhance patient management.

Trigeminal neuralgia (part I): Revisiting the clinical phenotype

Aims

We conducted a cross-sectional study to re-examine the clinical profile of patients with a clinical diagnosis of classical trigeminal neuralgia (CTN).

Methods

Inclusion criteria consisted of the International Headache Society’s published classification of CTN. For the specific purposes of the study, features such as autonomic signs, persistent background pain, attack durations of >2 minutes and reports of pain-related awakening were included. The demographic and clinical phenotype of each patient were carefully recorded for analysis.

Results

The study cohort consisted of 81 patients and based on reported attack duration these were divided into short (≤ 2 minutes, n = 61) and long (> 2 minutes, n = 20) groups for further analysis. The group with short attack duration neatly fit most of the criteria for CTN while the long attack group presents a more challenging diagnosis. There were no significant differences in pain severity, quality and location between the short and long attack groups. The frequency of persistent background pain was significantly higher in the long (70%) compared to the short attack group (29.5%, p = 0.001). There were significantly more reports of pain-related awakenings in the long (55%) than in the short attack groups (29.5%, p = 0.04). There were no significant differences in the frequency of autonomic signs between the short (21.3%) and long attack groups (40%, p = 0.1). In the short attack group, the presence of autonomic signs was significantly associated with longer disease duration, increased pain-related awakenings, and a reduced prognosis.

Conclusion

There are clear diagnostic criteria for CTN but often patients present with features, such as long pain attacks, that challenge such accepted criteria. In our cohort the clinical phenotype of trigeminal, neuralgiform pain with or without autonomic signs and background pain was observed across both short and long attack groups and the clinical implications of this are discussed.

Trigeminal neuralgia (part II): Factors affecting early pharmacotherapeutic outcome

Aims

We conducted a cohort study to examine demographic and clinical features associated with the pharmacotherapeutic outcome in classical trigeminal neuralgia (CTN) patients.

Methods

Patients with a clinical profile indicating a diagnosis of CTN, as per the International Headache Society’s published classification, were enrolled prospectively. Demographic and pain-related characteristics were carefully collected. For the purposes of the study, patients with features such as autonomic signs and longer attack duration were included. All patients were then initiated on a standardised and accepted stepped pharmacotherapeutic protocol for the management of CTN. Initial pain scores and prospectively collected pain scores from pain diaries were used to assess the treatment outcome, with a ≥50% reduction considered significant.

Results

A total of 86 patients were seen, of whom five had an underlying disorder that could account for the pain. The study cohort therefore consisted of 81 patients, and based on attack duration these were divided into short (≤2 minutes, n = 61) and long (>2 minutes, n = 20) groups, for further analysis. The features of these patients and a discussion on the differential diagnosis have been presented in part 1 of this report. Employing an accepted stepped pharmacotherapeutic protocol for the management of CTN, significant improvement was more frequent in the short (74%) than in the long attack group (50%, p = 0.05). In the short attack group there were statistically significant associations between a poor treatment response and longer disease duration, the presence of autonomic signs and atypical pain descriptors for pain quality ( p < 0.05).

Conclusion

This report supports previous findings that prolonged disease duration and autonomic signs are negative prognostic indicators. The present study now adds long attack duration as a further negative prognostic sign.

Perspectives on next steps in classification of oro-facial pain - part 2: role of psychosocial factors

This study was initiated by a symposium, in which the present authors contributed, organised by the International RDC/TMD Consortium Network in March 2013. The purpose of the study was to review the status of biobehavioural research - both quantitative and qualitative - related to oro-facial pain (OFP) with respect to the aetiology, pathophysiology, diagnosis and management of OFP conditions, and how this information can optimally be used for developing a structured OFP classification system for research. In particular, we address representation of psychosocial entities in classification systems, use of qualitative research to identify and understand the full scope of psychosocial entities and their interaction, and the usage of classification system for guiding treatment. We then provide recommendations for addressing these problems, including how ontological principles can inform this process.

A 2-year mean follow-up of oral appliance therapy for severe obstructive sleep apnea: a cohort study

OBJECTIVE

Oral appliances for treating severe obstructive sleep apnea (OSA) are recommended for patients who failed to comply with continuous positive airway pressure (CPAP) treatment. The objective of this study was to evaluate medium long-term outcome and success rates of oral appliances in patients with severe OSA.

METHODS

In a retrospective study, 52 OSA patients with an apnea-hypopnea index (AHI) ≥40, who did not tolerate CPAP treatment, were enrolled and fitted with a modified Herbst oral appliance. A 2-year mean follow-up including a second somnography was conducted in 36 of the patients.

RESULTS

A significant reduction (P < 0.0001) in the AHI was demonstrated between the initial somnography (55.25 ± 10.79,) and the followed one (17.74 ± 11.0, n = 36). Overall, 57.7% of total study subjects (n = 52) and 63.9% (n = 36) that had sequential sonmogarphy continued using the device. The reduction in AHI in the user group was 42.4 ± 3.1 (n = 23), which was significantly higher (P = 0.013) than in the non-user group (28.9 ± 17.2; n = 13). Moreover, 53% (n = 19) reached AHI of <15.

CONCLUSIONS

Oral appliances were found to be successful for treating for severe OSA after first-line treatment had failed.

Persistent orofacial muscle pain

The pathophysiology of persistent orofacial myalgia has been the centre of much controversy. In this article we suggest a novel descriptive term; 'persistent orofacial muscle pain' (POMP) and review current evidence that supports the hypothesis that the induction of POMP involves the interplay between a peripheral nociceptive source in muscle, a faulty central nervous system component and decreased coping ability. In this context it is widely accepted that a complex interaction of variable intrinsic and extrinsic factors act to induce POMP and dysfunction.

The International Classification of Headache Disorders: Accurate Diagnosis of Orofacial Pain?

The aim was to apply diagnostic criteria, as published by the International Headache Society (IHS), to the diagnosis of orofacial pain. A total of 328 consecutive patients with orofacial pain were collected over a period of 2 years. The orofacial pain clinic routinely employs criteria published by the IHS, the American Academy of Orofacial Pain (AAOP) and the Research Diagnostic Criteria for Temporomandibular Disorders (RDCTMD). Employing IHS criteria, 184 patients were successfully diagnosed (56%), including 34 with persistent idiopathic facial pain. In the remaining 144 we applied AAOP/RDCTMD criteria and diagnosed 120 as masticatory myofascial pain (MMP) resulting in a diagnostic efficiency of 92.7% (304/328) when applying the three classifications (IHS, AAOP, RDCTMD). Employing further published criteria, 23 patients were diagnosed as neurovascular orofacial pain (NVOP, facial migraine) and one as a neuropathy secondary to connective tissue disease. All the patients were therefore allocated to predefined diagnoses. MMP is clearly defined by AAOP and the RDCTMD. However, NVOP is not defined by any of the above classification systems. The features of MMP and NVOP are presented and analysed with calculations for positive (PPV) and negative predictive values (NPV). In MMP the combination of facial pain aggravated by jaw movement, and the presence of three or more tender muscles resulted in a PPV = 0.82 and a NPV = 0.86. For NVOP the combination of facial pain, throbbing quality, autonomic and/or systemic features and attack duration of > 60 min gave a PPV = 0.71 and a NPV = 0.95. Expansion of the IHS system is needed so as to integrate more orofacial pain syndromes.

[Antibiotic prophylaxis for the prevention of infective endocarditis--new guidelines of the American Heart Association]

Within the last twelve month both the working party of the British Society for Antimicrobial Chemotherapy and the American Heart Association have changed their attitude towards antibiotic prophylaxis for the prevention of infective endocarditis dramatically. The major change is the exclusion of the groups of patients formerly known as the "low and medium" risk groups from the new treatment group. A brief summary of the American as well as the British recommendations for adults and children is reported.

Orofacial pain in cancer: part II--clinical perspectives and management

Cancer-associated pain is extremely common and is associated with significant physical and psychological suffering. Unfortunately, pain associated with cancer or its treatment is frequently under-treated, probably due to several factors, including phobia of opioids, under-reporting by patients, and under-diagnosis by healthcare workers. The most common etiology of cancer pain is local tumor invasion (primary or metastatic), involving inflammatory and neuropathic mechanisms; these have been reviewed in Part I. As malignant disease advances, pain usually becomes more frequent and more intense. Additional expressions of orofacial cancer pain include distant tumor effects, involving paraneoplastic mechanisms. Pain secondary to cancer therapy varies with the treatment modalities used: Chemo-radiotherapy protocols are typically associated with painful mucositis and neurotoxicity. Surgical therapies often result in nerve and tissue damage, leading, in the long term, to myofascial and neuropathic pain syndromes. In the present article, we review the clinical presentation of cancer-associated orofacial pain at various stages: initial diagnosis, during therapy (chemo-, radiotherapy, surgery), and in the post-therapy period. As a presenting symptom of orofacial cancer, pain is often of low intensity and diagnostically unreliable. Diagnosis, treatment, and prevention of pain in cancer require knowledge of the presenting characteristics, factors, and mechanisms involved.

The distribution of oral mucosal pH values in healthy saliva secretors

OBJECTIVES

To establish the normal range of oral mucosal pH and to correlate these measurements to salivary flow rate in healthy individuals according to age and gender.

SUBJECTS AND METHODS

Measurements of pH levels using a flat pH meter and salivary secretion rates were established in eight mucosal sites from a total of 50 healthy individuals.

RESULTS

The mean pH (+/-s.d.) of all sites was 6.78 +/- 0.04 with significant differences between mean pH values in the palate (7.34 +/- 0.38), the floor of the mouth (6.5 +/- 0.3), the buccal mucosa (6.28 +/- 0.36) and the tongue (6.8 +/- 0.26). A significant correlation was found between age and pH at palatal and tongue sites but no gender effects were noted.

CONCLUSIONS

This method is easy and relatively quick to manipulate, and may offer many diagnostic possibilities for oral related diseases and disorders such as oral malodour, mouth breathing, dysgeusia, acidic diet consumption and gastrointestinal disorders affecting the mouth.

[Impaired sense of taste--diagnosis and treatment]

The sense of taste has great importance in health and disease. Complaints of oral discomfort associated with taste disturbances are increasingly met in the clinical setting. Altered taste perception can result from various underlying local or systemic pathology, as well as serious sensorial syndromes. Although they are not straightforward to diagnose and manage, it is important for the clinician to understand the pathphysiology of this chemosensory system, and to be able to use objective measures in order to quantify and classify the apparent symptoms, thus making the first step to correct diagnosis and treatment.

Intrathecally administered cholera toxin blocks allodynia and hyperalgesia in persistent pain models

In persistent pain, the spinal cord concentration of the opioid peptide dynorphin increases dramatically, yet the function of dynorphin remains unknown. If prodynorphin expression could be manipulated in vivo, it might be possible to determine what role dynorphin plays in persistent pain. Previous work in our laboratory showed that prodynorphin expression is regulated through the cyclic adenosine monophosphate pathway. Therefore, we attempted to enhance prodynorphin expression in the spinal cord of rats by stimulating adenylate cyclase with cholera toxin; however, contrary to our hypothesis, intrathecally administered cholera toxin did not enhance prodynorphin expression. Rather, cholera toxin suppressed the increase in prodynorphin produced by inflammation. Cholera toxin also inhibited the allodynia and hyperalgesia associated with inflammation and nerve injury. Interestingly, the antiallodynic and antihyperalgesic actions of cholera toxin were reversed with the opioid receptor antagonist, naloxone. These findings suggest that cholera toxin enhances or unmasks an endogenous opioid pathway to produce its antiallodynic and antihyperalgesic effects. Furthermore, these data indicate that the suppression of the inflammation-induced increase in spinal cord prodynorphin is caused by the opioid-mediated decrease in the nociceptive stimulus.

Inflammation with no axonal damage of the rat saphenous nerve trunk induces ectopic discharge and mechanosensitivity in myelinated axons

Inflammation along a nerve trunk with no frank axonal nerve damage produced by complete Freund's adjuvant (CFA) or Carrageenan is known to induce a painful peripheral neuropathy. In the present study, we examined the electrophysiological properties of myelinated axons (spontaneous discharge and mechanical sensitivity) at the inflamed nerve site. The rat saphenous nerves were exposed at mid-thigh level and wrapped in 2 mm wide bands of haemostatic oxidized cellulose (Oxycel) that were saturated with undiluted CFA. In the control rats the Oxycel) was saturated with saline. At postoperative days (PODs) 2-5 and 6-10, fine axon bundles were teased from the nerve, and electrophysiological recordings performed. At both time points spontaneous activity at the site of the application in CFA rats (PODs 2-5=9.9+/-2.5%: PODs 6-10=6.1+/-1.4%) was significantly higher than in the control animals (PODs 2-5=2.9+/-1.1%: PODs 6-10=1.6+/-1.4%: P=0.03, P=0.02, respectively). Mechanical sensitivity at both time points was significantly higher in CFA rats (PODs 2-5=12.6+/-3.1%: PODs 6-10=10.3+/-3.1%) than in saline rats (PODs 2-5=3.4+/-2.91%: PODs 6-10=0.8+/-1.0%: P=0.03, P=0.04, respectively). This study clearly shows that perineural inflammation with no axonal nerve damage induced by CFA application around the nerve trunk elevates spontaneous activity and induces mechanosensitivity in myelinated axons.

Neuropeptide Y in trigeminal ganglion following chronic constriction injury of the rat infraorbital nerve: is there correlation to somatosensory parameters?

The aim of this study was to investigate neuropeptide Y (NPY) levels in trigeminal ganglia following infraorbital nerve injury. Two experimental procedures were performed in three groups of rats: a unilateral chronic constriction injury (CCI) to the infraorbital nerve (n=13), nerve manipulation without CCI (n=13) and unoperated controls (n=8). All rats underwent baseline and regular assessment of mechanical withdrawal threshold (Von Frey) and reaction to pin prick as well as free behavior evaluations. CCI to the infraorbital nerve induced significant hyperalgesia and allodynia within 9-12 days. At 6 days seven rats were euthanized and trigeminal ganglia harvested for immunocytochemical (ICC) studies. The study was ended at 14 days when all rats were euthanized and their ganglia harvested for ICC and radioimmunoassay (RIA) studies. An increase in NPY levels was seen in the ipsilateral ganglia of manipulated and CCI rats at 6 days, when rats displayed no pain-related behavior. At 14 days, ICC and RIA both detected significant increases in NPY levels in the ipsilateral ganglia of CCI and manipulated rats but not in unoperated controls. The possible roles of NPY in pain modulation and nerve injury are discussed in light of these findings.

Primary vascular-type craniofacial pain

Primary vascular-type craniofacial pain comprises a group of pain disorders that share common diagnostic features. These are unilateral, episodic, pulsatile, severe pain. Accompanying phenomena include local autonomic (e.g., tearing, rhinorrhea) and systemic signs (e.g., nausea, photophobia). Primary vascular-type craniofacial pain includes migraine, cluster headache, and paroxysmal hemicrania. A new diagnostic entity, vascular orofacial pain, is suggested. Treatment of primary vascular-type craniofacial pain depends on its more specific diagnosis, and may be abortive or prophylactic. Diagnostic features, common pathophysiological mechanisms, and treatment modalities are discussed.

No sympathetic nerve sprouting in rat trigeminal ganglion following painful and non-painful infraorbital nerve neuropathy

Following sciatic nerve injury sympathetic invasion and basket formation is seen in dorsal root ganglia. We examined whether this phenomenon occurs in trigeminal ganglion (TG) following axotomy (IOAx) or chronic constriction injury to the infraorbital nerve (IOCCI). The IOCCI rats developed hyperresponsiveness to pinprick stimulation consistent with this model and the IOAx rats remained hyporesponsive for most of the study period. Immunocytochemistry employing antibodies to tyrosine hydroxylase showed no sympathetic invasion or basket formation 2 and 7 weeks post surgery. This study confirms previous work that found no sympathetic invasion of TG following injury, and shows that this finding is unaffected by the presence or absence of nerve injury induced hyperresponsiveness.

Co-localization of N-methyl-D-aspartate receptors and substance P (neurokinin-1) receptors in rat spinal cord

Glutamate, substance P (SP), and their receptors have been implicated in the initiation and maintenance of persistent pain through an interaction at second order spinal cord neurons. Employing well-characterized antibodies to the SP receptor and the N-methyl-D-aspartate receptor (NR1 subunit, splice variant missing exon 22), we demonstrate co-localization of these receptors on second order neurons at cervical, thoracic, lumbar, and sacral spinal cord levels. The co-localization was marked in lamina I of the dorsal horn at all levels and in the intermediolateral nucleus of the thoraco-lumbar spinal cord nuclei associated with autonomic function.

Odontalgia in vascular orofacial pain

A case of episodic, spontaneous odontalgia, aggravated by ingestion of cold food, with no apparent dental pathology is presented. Attempts at alleviating the pain by means of root canal treatment had failed in previous, similar episodes, and pain and pulpal hyperalgesia had shifted to other locations. Primary vascular orofacial pain was diagnosed and effective control obtained by prophylactic treatment with propranolol, a beta-adrenergic blocker. A prophylactic attempt with nifedipine, a calcium channel blocker, failed to alleviate the pain. This diagnostic entity and possible therapeutic approaches are discussed.

Actions of intrathecal diphtheria toxin-substance P fusion protein on models of persistent pain

Substance P (SP) plays a central role in the transduction of second messenger signals from primary afferent nociceptive terminals to second-order neurons in the spinal cord. We have tested a recombinant engineered diphtheria toxin/SP fusion protein (DAB389SP) in acute and chronic pain models in the rat. DAB389SP binds to the SP receptor (SPR) and is internalized and kills SPR-expressing cells by blocking cellular protein synthesis. DAB389SP delivery was by intrathecal infusion, of varying duration, at the lumbar level. In the chronic constriction injury model of neuropathic pain a significant reduction in mechanically induced hyperalgesia was obtained. This effect was less marked in an acute carageenan inflammation model. Although other pain characteristics (mechano-allodynia, cold-allodynia, and heat-hyperalgesia) showed some improvement, these were less pronounced. Immunocytochemistry revealed a toxin-induced reduction in lamina I, of SPR and of NMDA NR1 subunit receptor expressing neurons, and of c-Fos, an inducible molecular marker of persistent nociceptive activity. The use of cytotoxic fusion proteins to target specific cell types may be of considerable benefit in the study of nociception and the treatment of chronic pain.

Neuropathic orofacial pain

Neuropathic orofacial pain (NOP) is a challenging diagnostic problem. In some cases, symptomatology may be similar to that seen with dental pathology, resulting in unwarranted dental treatment. Rarely, NOP can herald serious disease or central tumors, and early diagnosis can be life-saving. The following review outlines the classification, clinical presentation, pathophysiology, and treatment of the more common NOP entities.

Craniofacial pain of myofascial origin: temporomandibular pain & tension-type headache

Craniofacial pain of myofascial origin is a common chronic disorder. When the pain is unilateral and located periauricularly, masticatory myalgia is likely. Tension-type headache is usually bilateral and affects the upper part of the head. The possible interrelationship with generalized myofascial disorders are discussed. Practical approaches to history-taking, diagnosis, and treatment are suggested.

Paroxysmal hemicrania. Case studies and review of the literature

Paroxysmal hemicrania is a vascular-type headache that is characterized by short bouts of severe unilateral pain in the area of the orbit and temple. A chronic and episodic form that has been described is similar to cluster headache and reflects a distinctive temporal pattern. Signs associated with paroxysmal hemicrania include ipsilateral conjunctival injection and tearing with nasal congestion and rhinorrhea. The condition's absolute response to indomethacin pharmacotherapy differentiates paroxysmal hemicrania from cluster headache. Typical symptoms usually make for a relatively straightforward diagnosis of paroxysmal hemicrania, but it may masquerade as pulpitic or temporomandibular-joint-related pain and may even herald systemic disease or malignancy. Paroxysmal hemicrania is a rare syndrome; 111 cases have been reported in the literature thus far. All of these cases have been reported by "headache specialists"; no cases of paroxysmal hemicrania were found in the dental literature. In this review, a relatively large series of seven new cases is reported; all seven were seen in an orofacial pain clinic.

Trigeminal neuralgia with lacrimation or SUNCT syndrome?

An intimate relationship between trigeminal neuralgia (TN) and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) syndrome, based on similar clinical signs and symptoms and on cases demonstrating possible "transformation" from one entity to the other, has been widely accepted. We evaluated the presence of lacrimation in 22 consecutive cases that had been diagnosed as TN. Ipsilateral lacrimation was reported by 6 such cases (5M, 1F). These cases responded to antineuralgic therapy with concomitant resolution of lacrimation and were clinically very similar to TN. The differential diagnosis and the possibility of lacrimation in TN are discussed.

Trigeminal neuralgic-type pain and vascular-type headache due to gustatory stimulus

We present a case of facial pain associated with sweet stimulus. An immediate, electric-like, short, unilateral pain was evoked by strong sweet gustatory stimulation. This was followed 6 to 8 hours later by a bilateral severe headache associated with bilateral tearing, rhinorrhea, periorbital swelling, flushing, and photophobia that lasted up to 2 days. The immediate pain that was experimentally induced with 2.5 grams of sucrose placed on the tongue could be abolished with carbamazepine. However, carbamazepine did not prevent the headache complex that appeared 6 to 8 hours later. Conversely, a trial with indomethacin abolished the late-onset headache, but not the immediate neuralgic-type pain. The independent nature of these pains suggests different pathophysiological mechanisms which are discussed.

SUNCT syndrome: case report and literature review

The case of a woman with short neuralgiform paroxysmal pain of 2 years duration is described. Pain attacks were always accompanied by ipsilateral lacrimation and conjunctival injection. Standard anti-neuralgic therapy, amitriptyline and indomethacin, failed to eliminate or reduce pain. At the end of a 30-month active period the patient seemed to have gone into remission. We believe this to be a case of short-lasting, unilateral, neuralgiform headache attacks with conjunctival injection and tearing (SUNCT), the first reported in the dental literature and the 24th in the general medical literature. The differential diagnosis of the case and relevant literature are discussed.

Orofacial pain with vascular-type features

OBJECTIVE

To examine whether a classifiable primary vascular-type craniofacial pain subgroup exists that predominantly affects intraoral structures.

STUDY DESIGN

Fifty-five patients were chosen prospectively according to the following inclusion criteria; periodic craniofacial pain that was unilateral, pulsatile, severe, and that may wake the patient from sleep. Accompanying phenomena could include local autonomic and/or systemic signs. Twenty-six cases could be further classified into one of the categories of vascular craniofacial pain. The remaining 29, all with predominantly intraoral pain, were not readily classifiable.

RESULTS

Of the 29 patients 70% were women, with an average onset-age of 42.6 years. All reported severe, episodic pain that was usually unilateral and lasted minutes to hours. In all, 55% of patients had autonomic or systemic signs, 48% had pulsatile pain, and 35.4% of patients were awakened by the pain.

CONCLUSION

Although clinical similarities were observed within these patients, further studies are needed to confirm vascular orofacial pain as a clear diagnostic category.

Palatal root hemisections and subsequent tooth restoration: a simple procedure?

This article describes a simple procedure for palatal root hemisection in maxillary molars and their subsequent restoration. Hemisection has several advantages over resection at all stages and allows for simple prosthetic restoration, especially when treating the palatal root.

Diagnosis and treatment of persistent pain after trauma to the head and neck

PURPOSE

A retrospective and prospective study on 22 cases of persistent pain after trauma to the head and neck is presented. According to the predominant symptoms and signs, pain patterns could be divided into musculoskeletal, vascular, and neuropathic, facilitating treatment decisions. Most cases were musculoskeletal in origin, with many demonstrating a combination of two or three pain states.

RESULTS

The variety of pain complaints and their underlying pathophysiology are discussed and treatments for specific pain states are examined.

CONCLUSION

Amitriptyline was the most useful drug in that it provided pain relief in musculoskeletal, vascular, and some neuropathic pain conditions. Multidrug therapy may be indicated in some recalcitrant cases, and drug alternatives are discussed.

Idiopathic trigeminal pain associated with gustatory stimuli

We present a unique case of a patient with facial pain evoked by gustatory stimuli. Pain was typically evoked by application of sucrose to the ipsilateral anterior 2/3 of the tongue, but not to the contralateral aspect. Pain was referred to the maxillary tuberosity area and, when stronger, to the infraorbital and supraorbital regions. Sucrose was most effective in eliciting pain, whilst saline, citric acid and water had a minimal effect. Spatial or temporal summation of gustatory stimuli was associated with stronger pain of longer duration and shorter latency. Some of the pain characteristics were similar to those of idiopathic trigeminal neuralgia. Thus, pain was elicited by innocuous ipsilateral stimuli, referred out of the stimulus zone, persisted beyond the period of stimulation and could be controlled with carbamazepine. We proposed a central neural mechanism for pain induction with convergence between gustatory stimuli afferents and pain pathways in the trigeminal system.

Bacterial colonization of the parotid duct in xerostomia

Salivary flow rate and bacterial colonization of the parotid main duct were investigated in 17 patients referred for sialography and in 10 healthy controls. Cultures in the controls were negative whilst the patient group revealed bacterial colonization of the main duct, especially in those with the lowest flow rates. The implications of this finding in patients at high risk of endocarditis who will be undergoing sialography are discussed.

Diagnosis of a sublingual epidermoid cyst using contrast medium radiography: a case report

A case of a sublingual epidermoid cyst is presented. The advantages of contrast medium radiography in diagnosis, localization and surgical treatment planning are exemplified.

The interleukin concept and the periodontal diseases

The interleukins are hormone-like substances found at sites of inflammation such as in rheumatoid arthritis and periodontal disease. The present article analyzes a hypothetical mechanism of periodontal pathogenesis, whose etiology is still unclear despite its high prevalence.

Peripheral T lymphocyte subsets in rapidly progressive periodontitis

The peripheral blood lymphocyte subsets of 10 patients with rapidly progressive periodontitis were investigated with monoclonal antibody. In 4 patients, the T helper/T suppressor ratio was increased. 5 others had a slightly reduced T helper/T suppressor ratio as compared to control group. These findings may indicate a possible cellular immune response in the pathogenesis of rapidly progressive periodontitis.

Lichen planus evoked by periodontal surgery

A case of Lichen Planus (LP) following periodontal surgery in a patient previously free of the disease is described. Genetic predisposition and lymphokine secretion stimulated by local trauma are suggested as a possible mechanism of the phenomenon. It is recommended that LP patients, especially those suffering from the erosive type, should be treated as conservatively as possible, minimizing the possibility of trauma to the oral tissues where local immunity may have been altered by a pathological process.

Development of resistant oral viridans streptococci after administration of prophylactic antibiotics: time management in the dental treatment of patients susceptible to infective endocarditis

The American Heart Association recommends prophylactic administration of penicillin before each dental session to patients susceptible to infective endocarditis. Such preventive treatment, however, may trigger the transient appearance of penicillin-resistant bacterial strains. In order to investigate the behavior of oral streptococci, 29 healthy volunteers who did not harbor penicillin-resistant viridans streptococci received 4 gm of phenoxymethyl penicillin orally over a period of 10 hours. This amount constituted the sole dose of antibiotics administered in the entire experiment. Daily specimens of oral flora were obtained for 14 successive days from each participant and incubated aerobically with a penicillin-saturated disk for 24 hours. Viridans streptococci were considered resistant when bacterial colonies grew adjacent to the disk for 1 day or more. The study population was divided into high- and low-resistance groups, according to the individual antibiograms. Resistant viridans streptococci were already detected at 6 hours after penicillin ingestion in nine (31%) of the subjects. Six months later, oral specimens were taken from ten randomly selected participants; these specimens served as a control. The difference in bacterial resistance between the high- and low-resistance groups was significant for the duration of 9 days, as was that between the high-resistance and control groups (p less than 0.05 in both cases). In order to minimize the odds that penicillin-resistant bacterial strains will develop in patients susceptible to infective endocarditis, elective dental treatments in these persons should be scheduled in intervals of not less than 10 days.

Human leukocyte antigen (HLA) DR4. Positive association with rapidly progressing periodontitis

The relationship between human leukocyte antigens (HLA) determinants and periodontitis has been examined by several authors without showing any particular pattern. However, no study has investigated the HLA-D determinants, which are generally associated with immune disorders, and rapidly progressive periodontitis (RPP). The HLA profile of 10 RPP patients was compared with that of a healthy control population (n = 120). Although no significant difference was found for HLA-A, HLA-B, and HLA-C, HLA-DR4 of the HLA-D group was found in 80% of patients but only in 38.3% of controls. A high frequency of HLA-DR4 has been reported in rheumatoid arthritis (RA) patients. This finding may be significant in light of previous reports highlighting similarities between RA and periodontal disease.