Topiramate inhibits adjuvant-induced chronic orofacial inflammatory allodynia in the rat.

Chronic orofacial pain disorders are common debilitating conditions, affecting the trigeminal system. Its underlying pathophysiological mechanisms are still unclear and the therapy is often unsatisfactory, therefore, preclinical models are crucial to identify the key mediators and novel treatment options. Complete Freund's adjuvant (CFA)-induced orofacial inflammatory allodynia/hyperalgesia is commonly used in rodents, but it has not been validated with currently used drugs. Here we tested the effects of the adjuvant analgesic/antiepileptic voltage-gated Na+ channel blocker complex mechanism of action topiramate in comparison with the gold standard antimigraine serotonin 5-HT1B/D receptor agonist sumatriptan in this model. CFA was injected subcutaneously into the right whisker pad of male Sprague-Dawley rats (250-300 g), then mechanonociceptive threshold values were investigated with von Frey filaments (3, 5, and 7 days after CFA injection). Effects of topiramate (30 mg/kg per os) and sumatriptan (1 mg/kg subcutaneous) on the adjuvant-induced chronic inflammatory orofacial allodynia were investigated 60, 120, and 180 min after the treatments each day. To determine the optimal concentration for drug effect analysis, we tested the effects of two different CFA-concentrations (1 and 0.5 mg/mL) on mechanonociceptive thresholds. Both concentrations of CFA induced a chronic orofacial allodynia in 60% of all rats. Although, higher CFA concentration induced greater allodynia, much more stable threshold reduction was observed with the lower CFA concentration: on day 3 the thresholds decreased from 18.30 g to approximately 11 g (low) and 5 g (high), respectively, however a slight increase was observed in the case of higher CFA concentration (on days 5, 7, and 11). In all investigation days, topiramate showed significant anti-allodynic effect comparing the pre and post drug dose and comparing the vehicle treated to the drug treated groups. Sumatriptan also caused a significant threshold increase compared to pre dose thresholds (day 3) and also showed a slight anti-allodynic effect compared to the vehicle-treated group (day 3 and 5). In the present study CFA-induced chronic orofacial allodynia was reversed by topiramate in rats validating the model with the adjuvant analgesic. Other than establishing a validated orofacial pain-related syndrome model in rats, new ways are opened for the repurposing of topiramate.

A male-specific mechanism of meningeal nociceptor sensitization promoting migraine headache.

BACKGROUND: We wished to explore possible sexual dimorphism in mechanisms sensitizing or activating meningeal nociceptors that can promote the headache phase of migraine. METHODS: Male and female C57BL6J mice received either supradural orexin B and an inflammatory mediator cocktail (IM) with migraine-like pain behaviors and photophobia recorded. Expression of orexin 2 receptor (OX2R) in trigeminal ganglion (TG) and phosphorylated extracellular signal-regulated kinases (ERK) levels in trigeminal nucleus caudalis (TNC) were evaluated. Orexin B-induced excitability of TG cells was assessed with patch-clamp electrophysiology. Intranasal delivery of CRISPR/Cas9 plasmids was used to edit the expression of OX2R in the TG. RESULTS: Supradural orexin B induced migraine-like pain behaviors, photophobia and increased TNC ERK phosphorylation exclusively in males. Blockade of orexin signaling with supradural suvorexant, a dual orexin receptor antagonist, prevented, but did not reverse, migraine-like pain in males induced by supradural IM cocktail. OX2R expression was higher in male TG and orexin B increased TG neuron excitability in males. Intranasal OX2R CRISPR/Cas9 reduced TG receptor expression and orexin B-induced TNC ERK phosphorylation and prevented migraine-like pain induced by supradural orexin B in males. CONCLUSIONS: Our studies reveal a male-specific mechanism of TG nociceptor sensitization and migraine-like pain behavior mediated by orexin B/OX2R signaling. Sexually dimorphic mechanisms of trigeminal nociceptor sensitization and activation offer opportunities to improve patient outcomes by considering patient sex and may influence clinical trial design and interpretation.

Management of trigeminal neuralgia by peripheral neurectomy.

Background: Peripheral neurectomy(PN)is a minimally invasive procedure, for the management of trigeminal neuralgi (TN)consisting of surgical avulsion of terminal branches of the trigeminal nerve. Aim: To assess the efficacy of PN in the treatment of refractory TN and their recurrences in a follow up of 18 months. Materials and Methodology: Retro-prospective and prospective study was conducted on randomly selected 30 TN patients irrespective of age, gender and socio-economic status. The branch of trigeminal nerve involved was identified according to the site of pain. Then the PN procedure was performed under local or general aesthesia. The follow up of each patient was done for next 18 months. Results: Mean age of the TN patients 53.17 ± 13.84 years, with 66.7% of patients were within 60 years of age. Male to female ratio was 1:1.5. All patients showed unilateral TN. Mostly 26.7% trigger point was located in lower lip followed by 13.3% in upper lip. After 3,6 and 9 months follow-up, none of the TN patients treated with PN had pain and none had any effect on general activity. However, from 12 months till 18 months' follow up, 2 (6.7%) patients reported of pain. Conclusion: PNs are viable treatment alternative for TN, although peripheral neurectomy has chances of reoccurrence but still offer better quality of life in patients for many years without relaps.

Neurosarcoidosis of the trigeminal nerve: clinical accompaniments, radiographic findings, and association with neuralgia.

BACKGROUND: Cranial neuropathy is a principal disease manifestation of neurosarcoidosis, but many forms remain poorly described, including trigeminal nerve disease despite its frequency in reported cohorts (5-12%). Herein, we characterize the clinical course of patients with neurosarcoidosis involving the trigeminal nerve. METHODS: A single-center retrospective cohort analysis of patients with biopsy-proven sarcoidosis involving the trigeminal nerve was conducted between 1/1/2000-3/7/2023. RESULTS: The trigeminal nerve was affected in 14/245 (5.7%) patients, being clinically symptomatic in 5/245 (2.0%) and asymptomatic with radiographic involvement in 9/245 (3.7%). 14/14 (100.0%) patients had systemic sarcoidosis. In the symptomatic group, trigeminal neuropathy was an inaugural feature in 4/5 (80.0%), unilateral in 5/5 (100.0%) with the V1 subdivision most affected (4/5, 80.0%), and associated with neuralgia in 2/5 (40.0%). On MRI, the cisternal nerve roots (9/14, 64.3%), Meckel's cave (7/14, 50.0%), and cavernous sinus (5/14, 35.7%) were most commonly affected, and 14/14 (100.0%) patients had extra-trigeminal neuroinflammation on cranial MRI. CSF was abnormal in at least one dimension in 11/12 (91.7%) tested. All three treated patients with symptomatic trigeminal neuropathy responded to immunomodulatory treatment, and symptomatic treatments for trigeminal neuralgia were helpful in two patients. After a median follow-up period of 63 months, the median modified Rankin scale score was 1 for both subgroups. CONCLUSION: Neurosarcoidosis may involve any portion of the trigeminal apparatus, and when affected, it frequently demonstrates a mismatch in radiographic involvement from its clinical manifestations of facial numbness and pain, and typically occurs in association with other clinical or radiographic manifestations of neurosarcoidosis.

Bilateral concurrent type I and type II persistent proatlantal arteries: A case report.

Transient embryonic carotid-vertebrobasilar anastomoses can intermittently persist beyond the embryonic period. These vascular anomalies are often serendipitously identified during evaluation for unrelated disease states and pathologies. The persistent proatlantal intersegmental artery is one such recognized rare fetal anastomotic connection, often arising unilaterally. Bilateral persistence of the proatlantal anastomosis is a rarer occurrence, seldom described in the literature. We report a case of bilateral concurrent type I and type II proatlantal arteries, describe the embryology of persistent carotid-vertebrobasilar anastomoses, and consider pertinent clinical implications.

Stretching of Mechanoreceptors in Superior Tarsal Muscle Reflexively Contracts Slow-Twitch Fibers in Facial Expression Muscles: A Case Series.

Levator palpebrae superioris muscle (LPSM) and facial muscles comprise fast-twitch fibers (FTFs) and slow-twitch fibers (STFs) but lack muscle spindles required to contract STFs reflexively. Voluntary contractions and microsaccades of FTFs in LPSM stretch mechanoreceptors in superior tarsal muscle (STM) to induce phasic contractions of STFs in LPSM and frontalis muscle via mesencephalic trigeminal nucleus (MTN). They also induce prolonged contractions of STFs in bilateral frontalis and orbital orbicularis oculi muscles and physiological arousal via MTN and rostral locus coeruleus (LC). We hypothesized that stretching of mechanoreceptors in STM also induces prolonged contractions of STFs in other facial expression muscles (FEMs) via rostral LC. To verify this hypothesis, we reported a case series of abnormal contractions of FEMs due to aponeurosis disinsertion and disordered mechanoreceptor stretching. The first and second cases, which showed unilaterally and bilaterally sensitized mechanoreceptors, respectively, recorded increased prolonged contractions of ipsilateral and bilateral grimacing muscles, respectively. The third and fourth cases with asymmetrically and bilaterally desensitized mechanoreceptors experienced asymmetrically and bilaterally decreased prolonged contractions of grimacing and smiling muscles, respectively. Preoperatively and after surgery was performed to adjust mechanoreceptor stretching and reinsert aponeuroses into tarsi, we evaluated prolonged contractions of grimacing and smiling muscles during primary gazing and facial expression movements. Surgery satisfactorily cured abnormal prolonged contractions of grimacing and smiling muscles. Stretching of mechanoreceptors in STM by microsaccades or voluntary contractions of FTFs in LPSM might activate rostral LC via MTN, which tonically or phasically stimulates FEM motor neurons to reflexively contract their STFs, respectively.

Developing a high fidelity, low cost simulation model for retrosigmoid craniotomy and microvascular decompression of the trigeminal nerve.

BACKGROUND: Trigeminal neuralgia is a very painful condition that may require a surgical approach as treatment, which is typically retrosigmoid craniotomy followed by microvascular decompression. Due to the limited margin for error when operating in the small triangular window of the cerebellopontine angle and the infrequency of this condition, the operating room can present a difficult learning environment for surgical trainees. Our aim is to create a synthetic, low-cost, high-fidelity, and largely reusable simulation model that will enable neurosurgical trainees to practice these procedural steps in a safe learning environment. MATERIALS AND METHODS: Design-based research was employed to develop the model through iterative micro-cycles, with expert evaluation from an educational and clinical team. The model was made from easy to source materials without advanced technology where sustainability, reproduction at scale and cost where significant considerations. RESULTS: Our model effectively simulates a retrosigmoid craniotomy and microvascular decompression of the trigeminal nerve. The model consists of two distinct parts that are made of synthetic materials. Part A is a single-use, moulded portion of the skull, while part B depicts the cerebellopontine angle and some of its internal anatomical and pathological structures crucial to carrying out all the steps to this procedure. Part A sits ergonomically flush on top of Part B, with both parts subsequently clamped to the table. CONCLUSIONS: As a proof of concept, we report the development and utilisation of a novel, low-cost, replicable retrosigmoid craniotomy and microvascular decompression of the trigeminal nerve simulation model.

Trigeminal n eu ra l gia diagnosis - a c ha l lenge - a cros s-se ct ional sur ve y to a ssess the k nowledge and a ttit ud e among t he dentists of S au di A ra bia.

OBJECTIVE: To analyse the knowledge level and attitude of Saudi dentists regarding trigeminal neuralgia. METHODS: The cross-sectional study was conducted from 17/12/ 2020 - 9/2/2021 at Prince Sat t am Bin Abdulaziz University, Al-Kharj, Riyadh Elm University, Riyadh, and Dar Al-Uloom University, Riyadh, Kingdom of Saud i Arabia. The sample comprised dentists and postgraduate dental students from every speciality. Data was collected online using a predesigned self-structured questionnaire consisting of three par ts, assessing knowledge, practice and attitude of the subjects. Data was analysed using SPSS 22. RESULTS: A total of 202 questionnaire about the knowledge level and attitude of Saudi dentists regarding trigeminal neuralgia were completed. The knowledge level was significantly higher in those senior age group compared to the young dentists with respect to the type of pain observed in TN, the unilateral pain of TN, and the abrupt, unexpected and transient nature of TN pain, local anaesthetic, the first-line treatment for TN, and the effect of TN on oral hygiene. CONCLUSIONS: Older and experienced dentists had more knowledge than younger and less experienced ones.

Epidemiology and clinical features of short-lasting unilateral neuralgiform headache attacks: A systematic review and meta-analysis.

BACKGROUND: To synthesize the available epidemiologic data on short-lasting unilateral neuralgiform headache attacks (SUNHA). This, in turn, might inform diagnostic work-up and clinical decision-making. METHODS: EMBASE and PubMed were searched for observational studies reporting on the prevalence or relative frequency of SUNHA or its individual clinical features. Two investigators independently conducted title and abstract screening, full-text review, data extraction, and risk of bias assessment, and random-effects meta-analyses were performed to estimate the prevalence or relative frequency of SUNHA and its individual clinical features. RESULTS: Fifteen clinic-based studies met our eligibility criteria. Of these, five studies reported estimates on the relative frequency of SUNHA among adults evaluated for headache or facial pain, yielding a pooled relative frequency as 0.32% (95% confidence interval = 0.17-0.62; I2 = 89.9%). Most often, SUNHA presented as episodic, side-locked stabbing headache of severe pain intensity, predominantly affecting the ophthalmic and/or maxillary branch of the trigeminal nerve. The most common cranial autonomic features were lacrimation, conjunctival injection, rhinorrhea and nasal congestion. CONCLUSIONS: SUNHA is a rare headache disorder with distinct clinical features. However, our findings must be interpreted with caution as a result of between-study heterogeneity and lack of population-based studies, underscoring the need for further epidemiologic research.

Repeat percutaneous rhizotomy for trigeminal neuralgia is not associated with an increased risk of postoperative complications.

BACKGROUND AND OBJECTIVES: Patients undergoing percutaneous rhizotomy for trigeminal neuralgia (TN) may require several procedures to manage their pain. However, it is not fully understood whether repeat procedures influence postoperative complication rates. METHODS: We retrospectively reviewed patients undergoing rhizotomy at our institution from 2011 to 2022. Patients were included only if they had no history of prior interventions including microvascular decompression (MVD) or radiosurgery. We collected baseline patient information, pain characteristics, and postoperative complications for each patient. Patients were dichotomized into those undergoing primary rhizotomy versus those undergoing a repeat rhizotomy. Potential drivers of postoperative complications were included in a multivariate logistic regression model. RESULTS: Of the 1904 cases reviewed, 965 met our inclusion criteria. 392 patients underwent primary rhizotomy, and 573 patients underwent repeat rhizotomies. The repeat rhizotomy group was significantly older, p<0.001. Patients in the repeat rhizotomy group expressed higher frequencies of bilateral pain, p=0.01. Patients in the repeat rhizotomy group demonstrated a significantly higher rate of preoperative numbness and postoperative numbness, p<0.001. There were no significant differences in any of the considered complications between the single rhizotomy and repeat rhizotomy groups. On multivariate logistic regression, repeat rhizotomy did not predict an increased risk of any postoperative complications, p=0.14. CONCLUSIONS: Patients undergoing repeat rhizotomy may be at risk of postoperative numbness but are not at increased risk for postoperative complications. These results are of use to patients who are poor surgical candidates, and thus may require multiple rhizotomies to effectively manage their pain over time.

Idiopathic Intracranial Hypertension as a Differential Diagnosis in Persistent Idiopathic Facial Pain: A Case Report.

Persistent idiopathic facial pain (PIFP), previously known as atypical facial pain (ATFP), is a chronic pain disorder with the characteristic of persistent, undulating pain in the face or the teeth without a known cause or any structural correlation. Women are more commonly affected than men. We report a case of a 38-year-old married female patient with a history of Crohn's disease who presented to the oral and maxillofacial surgery (OMFS) clinic with chronic dull bilateral facial pain and headache mainly affecting the right side of the face and neck without a known cause. She was initially diagnosed with PIFP due to a badly decayed right wisdom tooth. Wisdom teeth were extracted secondary to vague complaints of discomfort due to wisdom teeth; however, no significant improvement was noticed. Further investigations were carried out with new CT scans and magnetic resonance venography (MRV), which revealed evidence of having idiopathic intracranial hypertension (IIH), described as increased intracranial pressure with facial pain, headache, tinnitus, and papilledema. The patient was referred to neurology and received appropriate treatment. She began her treatment with topiramate, then transitioned to acetazolamide, underwent bilateral botulinum toxin (botox) injections into the temporal region, and underwent regular follow-up. The patient was significantly improved. Idiopathic intracranial hypertension must be ruled out in cases of PIFP that do not respond to ordinary treatment measures.

Port-Wine Stains and Intraoral Hemangiomas: A Case Series.

Port-wine stains (PWSs), also called port-wine birthmarks or nevus flammeus, are hamartomatous vascular capillary malformations that clinically appear as erythematous areas on the buccal mucosa, vermilion border of the lip, gingiva, or pink to port-wine-colored patches on skin since birth and persist throughout life. On the face, they occur in the area supplied by the trigeminal nerve. PWSs have structural abnormalities of the intradermal capillaries. PWSs on the skin and oral mucosa contain ectatic capillaries in the dermis and submucosa, respectively. PWSs occur anywhere, and the oral mucosa is no exception. PWSs on the facial skin lead to cosmetic disfigurement and create social stigma. Clinically, PWSs start as flat, pink, or red patches and may darken, thicken, and develop nodules over time. The diagnosis of PWSs is primarily clinical. PWSs are complex vascular malformations with significant clinical, psychosocial, and therapeutic challenges. This article enlightens a series of cases of PWSs on the facial skin and capillary hemangioma on the gingiva, buccal mucosa, and lip diagnosed by a diascopy test, etiopathogenesis, differential diagnosis, and management of PWSs.

Temporary Gasserian ganglion stimulation utilizing SNM electrode in subacute herpetic trigeminal neuralgia.

Objective: Gasserian ganglion stimulation (GGS) is a neuromodulation technique that has been extensively applied in treating postherpetic trigeminal neuralgia. However, permanent implantation of GGS was preferred in most treatment approaches. Few studies have investigated temporary GGS for the treatment of acute/subacute herpetic trigeminal neuralgia. Moreover, previous research has reported lead dislocation when utilizing traditional electrodes, which was associated with poor pain relief. In GGS research, preventing the accidental displacement of lead following implantation has consistently been a primary objective. Methods: We report a case of a 70-year-old woman with subacute herpetic trigeminal neuralgia who underwent temporary GGS for 14 days utilizing a sacral neuromodulation (SNM) quadripolar-tined lead. Computed tomography-guided percutaneous foramen ovale (FO) puncture and temporary SNM electrode implantation were performed during the surgery. A telephone interview was conducted to record a 12-month follow-up. Results: At admission, zoster-related trigeminal pain severity was assessed to be 9/10 on the visual analog scale (VAS). After a 14-day GGS treatment, the pain assessed on the VAS score reduced to 1/10 at discharge but increased to 4/10 at the 12-month follow-up after surgery. Additionally, the anxiety level improved from 58 points to 35 points on the Self-Rating Anxiety Scale (SAS), and the depression level improved from 62 points to 40 points on the Self-Rating Depression Scale (SDS). The Physical Component Summary score of the 12-item Short-Form Health Survey (SF-12) increased from 33.9 to 47.0, and the Mental Component Summary (MCS) score of the SF-12 increased from 27.4 to 41.9. Conclusion: Temporary GGS might be a potentially effective treatment for subacute herpetic trigeminal neuralgia, and an SNM electrode might be a good choice for reducing the risk of dislocation.

Intra-fractional corrections and clinical outcomes in frameless image-guided radiosurgery for trigeminal neuralgia.

Purpose: Precision targeting is crucial to successful stereotactic radiosurgery for trigeminal neuralgia (TGN). We investigated the impact of intra-fractional 6-dimensional corrections during frameless image-guided radiosurgery (IGRS) for pain outcome in TGN patients. Materials and methods: A total of 41 sets of intra-fractional corrections from 35 patients with TGN treated by frameless IGRS from 2009 to 2013 were retrospectively studied. For each IGRS, the intra-fractional 6-dimensional shifts were conducted at 6 couch angles. Clinical pain outcome was recorded according the Barrow Neurological Institute (BNI) 5-points score. The relationship in 6-dimensional corrections and absolute translational distances between patients with pain relief score points <2 versus ≥2 were analyzed. Results: The absolute mean lateral, longitudinal, and vertical translational shifts were 0.46 ± 0.15 mm, 0.36 ± 0.16 mm and 0.21 ± 0.08 mm, respectively, with 97% of translational shifts being within 0.7 mm. The absolute mean lateral (pitch), longitudinal (roll), and vertical (yaw) rotational corrections are 0.33 ± 0.24°, 0.18 ± 0.09°, and 0.27 ± 0.15°, respectively, with 97% of rotational corrections being within 0.6°. The median follow-up duration for pain outcome was 26 months after IGRS. The average calculated absolute shift for patients with pain relief <2 and ≥2 BNI points, were 0.228 ± 0.008 mm and 0.259 ± 0.007 mm, respectively. There was no statistically significant difference in the translational shifts, rotational corrections or absolute distances between these two patient groups. Conclusions: Our data demonstrate high spatial targeting accuracy of frameless IGRS for TGN with only nominal intra-fraction 6-dimensional corrections.

Factors associated with outcomes following microvascular decompression for the treatment of primary trigeminal neuralgia in adults: a systematic review and meta-analysis.

This study aimed to evaluate pain assessment strategies and factors associated with outcomes after microvascular decompression for the treatment of primary trigeminal neuralgia in adults. We conducted a systematic review and meta-analysis of English, Spanish, and French literature. We searched three databases, PubMed, Ovid, and EBSCO, from 2010 to 2022 and selected studies including patients with primary trigeminal neuralgia, clear pain assessment, and pain outcomes. Population means and standard deviations were calculated. Studies that included factors associated with postoperative outcomes were included in the meta-analysis. A total of 995 studies involving 5673 patients with primary trigeminal neuralgia following microvascular decompression were included. Patients with arteries compressing the trigeminal nerve demonstrated optimal outcomes following microvascular decompression (odds ratio [OR]= 0.39; 95% confidence interval [CI] = 0.19-0.80; X2 = 46.31; Dof = 15; I2 = 68%; P = < 0.0001). Conversely, when comparing arterial vs venous compression of the trigeminal nerve (OR = 2.72; 95% CI = 1.16-6.38; X2 = 23.23; Dof = 10; I2 = 57%; P = 0.01), venous compression demonstrated poor outcomes after microvascular decompression. Additionally, when comparing single-vessel vs multiple-vessel compression (OR = 2.72; 95% CI = 1.18-6.25; X2 = 21.17; Dof = 9; I2 = 57%; P = 0.01), patients demonstrated unfavorable outcomes after microvascular decompression. This systematic review and meta-analysis evaluated factors associated with outcomes following microvascular decompression (MVD) for primary trigeminal neuralgia (PTN). Although MVD is an optimal treatment strategy for PTN, a gap exists in interpreting the results when considering the lack of evidence for most pain assessment strategies.

The influence of transcranial direct current stimulation to the trigeminal nerve on attention and arousal.

One mechanism by which transcranial direct current stimulation (tDCS) has been proposed to improve attention is by transcutaneous stimulation of cranial nerves, thereby activating the locus coeruleus (LC). Specifically, placement of the electrodes over the frontal bone and mastoid is thought to facilitate current flow across the face as a path of least resistance. The face is innervated by the trigeminal nerve, and the trigeminal nerve is interconnected with the LC. In this study, we tested whether stimulating the trigeminal nerve impacts indices of LC activity and performance on a sustained attention task. We replicated previous research that shows deterioration in task performance, increases in the rate of task-unrelated thoughts, and reduced pupil responses due to time on task irrespective of tDCS condition (sham, anodal, and cathodal stimulation). Importantly, tDCS did not influence pupil dynamics (pretrial or stimulus-evoked), self-reported attention state, nor task performance in active versus sham stimulation conditions. The findings reported here are consistent with theories about arousal centered on a hypothesized link between LC activity indexed by pupil size, task performance, and self-reported attention state but fail to support hypotheses that tDCS over the trigeminal nerve influences indices of LC function.

An anatomical study of the subarachnoid space surrounding the trigeminal ganglion in horses-in preparation for a controlled glycerol rhizotomy in equids.

Introduction: Equine trigeminal-mediated headshaking is a painful neuropathic disorder comparable to trigeminal neuralgia in humans. The selective destruction of pain fibers within the trigeminal ganglion, called rhizotomy, is the surgical treatment of choice for idiopathic trigeminal neuralgia refractory to medical treatment in humans. The human trigeminal ganglion is enclosed by a dural recess called the Meckel's or trigeminal cave, in which the ganglion is surrounded by a cerebrospinal fluid (CSF)-filled subarachnoid space. During glycerol rhizotomy, glycerol is percutaneously injected in this CSF-filled space. Until now, information about the anatomy of the dural recess and the subarachnoid space surrounding the trigeminal ganglion is lacking in horses. The aim of this study was to explore if a CSF-filled subarachnoid space around the trigeminal ganglion exists in horses. Materials and methods: Six equine cadaver heads were investigated for CSF accumulation around the ganglion with a 3 Tesla MRI. After anatomical dissection to expose the trigeminal root, a polymer-based radiopaque contrast agent was injected through the porus trigeminus into the subarachnoid space (cisternography). The exact delineation and the volume of the contrast agent accumulation were determined on subsequent micro-computed tomographic scans and segmentation. Finally, the distribution of the contrast agent within the subarachnoid space was examined histologically in three specimens. Results: In all 12 specimens included in this study, the trigeminal ganglion was surrounded by a subarachnoid space forming a trigeminal cistern. The mean volume of the trigeminal cave in this study was 0.31 mL (±SD: 0.11 mL). Distribution of the contrast agent along the peripheral nerves (i.e., ophthalmic, maxillary and/or mandibular nerve) was observed in 7 out of 12 specimens. Discussion/conclusion: A subarachnoid space surrounding the trigeminal ganglion exists in the horse and could be targeted for glycerol rhizotomy in horses suffering from trigeminal-mediated headshaking. However, the clinical relevance of contrast agent distribution along the peripheral nerves remains to be assessed.

Evaluating the Influence of Acute and Chronic Orofacial Pains on the Overall Comprehensive Quality of Life.

Background Orofacial discomfort refers to various disorders that affect the mouth, jaws, and face. These conditions may substantially influence a person's quality of life (QoL). This kind of pain may be categorised into two primary classifications: acute and chronic. Acute orofacial pain (OFP) usually occurs suddenly and lasts for a short period. It is commonly caused by specific factors such as dental treatments, traumas, or infections. Hence, this study aimed to assess the influence of acute and chronic orofacial discomfort on the overall QoL. Methodology This research used a convenience sample to gather data from the five groups. It was conducted as a cross-sectional study. Four categories of OFP syndromes were utilised: temporomandibular disorders (TMDs), atypical dental pain (ADP), trigeminal neuralgia (TN), and persistent dentoalveolar pain disorder (PDAP). In addition, a control group consisting of individuals who did not experience any discomfort was also included in the study. Participants received a standardised explanation of the questionnaires utilised, and in most instances, they completed them at the clinic under the supervision of one of the investigators. Results The correlations between each version of the Oral Health Impact Profile (OHIP) were statistically significant (p < 0.001), with correlation values ranging from 0.92 to 0.97. When comparing the occurrence of OHIP items across the four pain types, we identified 18 variations that exceeded the 35% prevalence threshold we established for identifying important items that frequently occur out of the 315 comparisons. The question "Have you had a painful aching in your mouth?" showed a low frequency in patients with TN, TMD, and ADP but a significant prevalence in patients with PDAP (90%). This difference in prevalence across pain types was the biggest seen. The question that seemed to distinguish between the pain categories most effectively was "Have you experienced a toothache?" This question had a high occurrence in PDAP (65%) and ADP (60%), perhaps allowing for differentiating these two diseases from TN and TMD. The highest prevalence differences, over 30%, were most often seen when PDAP was included as one of the disorders being compared. ADP had the fewest variances, over 30%, occurring just seven times. Conclusion Both acute and chronic OFPs have a major negative influence on QoL, but they affect it differently and to differing extents. Injury-related acute pain obviously poses rapid and severe restrictions on physical function and causes temporary psychological distress and temporary social exclusion. On the other hand, chronic pain for the patient always implies being locked in a physical world that does not allow him or her to bypass physical limitations, psychological disorders remain constant, and isolation from other people persists for life.

"Letter to the editor, clinical characteristics and outcomes after trigeminal schwannoma resection: a multi-institutional experience".

The recent article "Clinical characteristics and outcomes after trigeminal schwannoma resection: a multi-institutional experience" by Nandoliya et al. offers critical insights into the management of trigeminal schwannomas (TS). This multi-institutional study, encompassing 30 patients over 18 years, highlights various surgical approaches, achieving gross-total resection in 53% of cases, and emphasizes the balance between resection and neurological preservation. The use of intraoperative neuromonitoring in 77% of cases is noted for minimizing morbidity. Despite a 13% complication rate, most were transient. Long-term follow-up data show a low recurrence rate, advocating for ongoing surveillance. The study underscores the importance of tailored surgical strategies, and the discussion of classification systems aids in contextual understanding. While the findings are robust, further research into adjuvant therapies and emerging technologies is warranted. This comprehensive overview advances our understanding of TS, promoting a patient-centered approach to surgical management.

Artificial intelligence and headache.

BACKGROUND AND METHODS: In this narrative review, we introduce key artificial intelligence (AI) and machine learning (ML) concepts, aimed at headache clinicians and researchers. Thereafter, we thoroughly review the use of AI in headache, based on a comprehensive literature search across PubMed, Embase and IEEExplore. Finally, we discuss limitations, as well as ethical and political perspectives. RESULTS: We identified six main research topics. First, natural language processing can be used to effectively extract and systematize unstructured headache research data, such as from electronic health records. Second, the most common application of ML is for classification of headache disorders, typically based on clinical record data, or neuroimaging data, with accuracies ranging from around 60% to well over 90%. Third, ML is used for prediction of headache disease trajectories. Fourth, ML shows promise in forecasting of headaches using self-reported data such as triggers and premonitory symptoms, data from wearable sensors and external data. Fifth and sixth, ML can be used for prediction of treatment responses and inference of treatment effects, respectively, aiming to optimize and individualize headache management. CONCLUSIONS: The potential uses of AI and ML in headache are broad, but, at present, many studies suffer from poor reporting and lack out-of-sample evaluation, and most models are not validated in a clinical setting.