Altered somatosensory processing in secondary trigeminal neuralgia: A case report

Secondary trigeminal neuralgia might be very rarely preceded by trigeminal neuropathic pain. The patient, in this case, presented with paroxysmal pain in the left mandible and numbness of the lower lip and tongue. Sensory testing of these areas revealed cold and heat hyperalgesia and mechanical hyposensitivity in the mandibular region. Magnetic resonance imaging showed a mass in the left cerebellopontine angle. The patient was prescribed systemic mirogabalin (2.5 mg/day), which provided some relief until the tumor was removed. The histopathological diagnosis was an epidermoid tumor. This article discusses the clinical characteristics and sensory testing findings that distinguish secondary trigeminal neuralgia from trigeminal neuropathic pain based on the International Classification of Orofacial Pain.

The role of the P2X4 receptor in trigeminal neuralgia, a common neurological disorder

Neurological disorders, which include various types of diseases with complex pathological mechanisms, are more common in the elderly and have shown increased prevalence, morbidity and mortality worldwide. Unfortunately, current therapies for these diseases are usually suboptimal or have undesirable side effects. This necessitates the development of new potential targets for disease-modifying therapies. P2X4R, a type of purinergic receptor, has multiple roles in neurological disorders. In this review, we briefly introduce a neurological disorder, trigeminal neuralgia and its' symptoms, etiology and pathology. Moreover, we focused on the role of P2X4R in neurological disorders and their related pathophysiologic mechanisms. Further studies of P2X4R are required to determine potential therapeutic effects for these pathophysiologies.

Idiopathic Facial Pain Syndromes–An Overview and Clinical Implications

BACKGROUND

Idiopathic facial pain syndromes are relatively rare. A uniform classification system for facial pain became available only recently, and many physicians and dentists are still unfamiliar with these conditions. As a result, patients frequently do not receive appropriate treatment.

METHODS

This article is based on pertinent publications retrieved by a selective search in PubMed, focusing on current international guidelines and the International Classification of Orofacial Pain (ICOP).

RESULTS

The ICOP subdivides orofacial pain syndromes into six major groups, the first three of which consist of diseases of the teeth, the periodontium, and the temporomandibular joint. The remaining three groups (non-dental facial pain) are discussed in the present review. Attack-like facial pain syndromes most closely resemble the well-known primary headache syndromes, such as migraine, but with pain located below the orbitomeatal line. These syndromes are treated in accordance with the guidelines for the corresponding types of headache. Persistent idiopathic facial pain (PIFP) is a chronic pain disorder with persistent, undulating pain in the face and/or teeth, without any structural correlate. Since this type of pain tends to become chronified after invasive procedures, no dental procedures should be performed to treat it if the teeth are healthy; rather, the treatmentis similar to that of neuropathic pain, e.g., with antidepressant and anticonvulsive drugs. Neuropathic facial pain is also undulating and persistent. It is often described as a burning sensation, and neuralgiform attacks may additionally be present. Trigeminal neuralgia is a distinct condition involving short-lasting, lancinating pain of high intensity with a maximum duration of two minutes. The first line of treatment is with medications; invasive treatment options should be considered only if pharmacotherapy is ineffective or poorly tolerated.

CONCLUSION

With the aid of this pragmatic classification system, the clinician can distinguish persistent and attack-like primary facial pain syndromes rather easily and treat each syndrome appropriately.

Novel fluoroscopic landmark to significantly facilitate the visualization of foramen ovale in treating idiopathic trigeminal neuralgia

BACKGROUND AND OBJECTIVES

Access through the foramen ovale (FO) is essential in performing trigeminal ganglion injection, glycerol rhizolysis, balloon compression, and radiofrequency thermocoagulation (RFT) to treat idiopathic trigeminal neuralgia (ITN). However, identification of the FO under fluoroscopy can be difficult and time-consuming, and thus exposes patients to increased radiation and procedure risks. Here we present the 'H-figure' as a novel fluoroscopic landmark to quickly visualize the FO.

METHODS

The H-figure landmark can be recognized as the medial border of the mandible and the lateral edge of the maxilla as the two vertical lines, and the superior line of petrous ridge of temporal bone (S-P-T line) as the horizontal line, and the FO fluoroscopic view is then optimized at the center of the H-figure immediately above the S-P-T line. We applied this landmark in a clinical cohort of 136 patients with ITN who underwent fluoroscopy-guided RFT of the trigeminal ganglion. We also compared the H-figure method with the traditional method. The primary outcome was the total number of fluoroscopic images required to visualize the FO (as a proxy of radiation exposure). Secondary measures included the procedure time required to finalize the FO view and the sensory testing voltage for paresthesia.

RESULTS

With the H-figure approach we were able to view the FO with an average of 4.2 fluoroscopic shots at an average time of 6.8 min. When compared with the non-H-figure traditional technique, the H-figure method required almost half the fluoroscopic shots in nearly half the procedure duration time, and paresthesia was evoked with half of the voltage.

CONCLUSION

The H-figure is an easy fluoroscopic landmark that can help to view the FO with less radiation and procedure time, and the needles placed with this approach can be closer to the target for the RFT treatment of patients with ITN.

Structural and Functional Brain Abnormalities in Trigeminal Neuralgia: A Systematic Review

AIMS

To evaluate the available literature on structural and functional brain abnormalities in trigeminal neuralgia (TN) using several brain magnetic resonance imaging (MRI) techniques to further understand the central mechanisms of TN.

METHODS

PubMed and Web of Science databases and the reference lists of identified studies were searched to identify potentially eligible studies through January 2019. Eligible articles were assessed for risk of bias and reviewed by two independent researchers.

RESULTS

A total of 17 articles meeting the inclusion criteria were included in this study. The methodologic quality of the included studies was moderate. A total of 10 studies evaluated structural gray matter (GM) changes, and there was reasonable evidence that the GM of some specific brain regions changed in TN patients. In addition, there was a significant change in the root entry zone of the trigeminal nerve and in several regions of white matter. Functional changes in resting state were assessed in 9 studies. TN patients showed increased activation of resting state, and this activation was reduced in specific brain regions. There were several studies that focused on the correlation between functional parameters or strength of functional connectivity and clinical features (eg, visual analog score and pain duration), but each study focused on different brain areas or different functional connectivities within the brain.

CONCLUSION

There is moderate evidence that TN patients show structural brain differences in specific cortical and subcortical regions. In addition, TN patients show changes in pain-related functional connections in the resting state. Future research should focus on longitudinal designs and integration of different brain-imaging techniques.

Painful Post-traumatic Trigeminal Neuropathy Occurs After Third Molar Extraction

Painful post-traumatic trigeminal neuropathy (PTTN), or anesthesia dolorosa, is a condition on the same continuum as trigeminal neuralgia. Unlike trigeminal neuralgia, trigeminal neuropathy is a more significant state of neural pathology resulting in constant pain opposed to the episodic nature of trigeminal neuralgia. This typically occurs after facial trauma or as a complication from some treatments for trigeminal neuralgia. Useful diagnostic features that can help distinguish PTTN are an identified trauma to the nerve and other clinical features such as facial swelling. The presented case describes a classic presentation after third molar (wisdom tooth) removal and a review of pertinent literature.

Idiopathic Trigeminal Neuralgia (ITN): Facts and Fiction

In this paper the authors present neuroanatomical and neurophysiological arguments against the microvascular compression in the root entry zone of trigeminal nerve nerve as an ethiopathogenetic factor of ITN. Clinical experience has proven that compression of mixed sensorymotor nerve (peripheral or central one), cannot provoke paroxysmal neuralgic pain. The authors conclude that the well known fact that dental pulp has only pain sensory modality brings up the question what might be consequence of tooth extraction where neural fibers are broken in the innervation areas of maxillar and mandibular nerve. The answer could be only one. If exclusive algophoric deafferentation hypersensitivity after tooth extraction exceeds a certain threshold, patients will experience paroxysmal neuralgic pain. Broken neural fibers develop pathological ephaptic communication with other trigeminal sensory modalities through supraspinal central structures responsible for the transmision of dental pulp pain. This can explain trigger phenomena and latency between the touching of circumoral areas and onset of neuralgic paroxysm, which is a central epileptic phenomenon. In conclusion, the so-called idiopathic trigeminal neuralgia (ITN) is the expression of algophoric deafferentation hypersensitivity after tooth extraction.

Comparison of the Neuropathic Pain Symptoms and Psychosocial Impacts of Trigeminal Neuralgia and Painful Posttraumatic Trigeminal Neuropathy

AIMS

To compare the impacts of trigeminal neuralgia (TN) and painful posttraumatic trigeminal neuropathy (PPTTN) on psychologic function and health-related quality of life (HRQoL) using a comprehensive quantitative assessment.

METHODS

This was a comparative cross-sectional study. A total of 97 patients diagnosed with PPTTN and 40 patients diagnosed with TN who sought treatment at an orofacial pain clinic completed standardized self-report measures of pain intensity, neuropathic symptoms, pain self-efficacy, mood, and indicators of general and oral HRQoL. Differences between the PPTTN and TN groups were tested, and associations of each condition with pain severity, psychologic function, and HRQoL were examined.

RESULTS

The majority of PPTTN (66%) and TN patients (80%) were affected by orofacial pain. Pain attacks were more frequent in TN (71%) than PPTTN (28%) patients, while numbness was more common in PPTTN (51%) than TN (12%) patients. Pain intensity was higher in TN for intermittent and affective pain dimensions. Both PPTTN and TN had a significant, but comparable, impact on patients' oral HRQoL. The burden of condition on overall health was significantly more pronounced in patients with TN than PPTTN, with evident differences in the mobility and self-care domains. There was a trend showing that more TN (54%) than PPTTN (36%) patients reported signs of depression, but clinically significant anxiety was comparably high in both groups (34% to 39%). Anxiety and pain self-efficacy were closely related to oral and general health statuses in both groups.

CONCLUSIONS

Both TN and PPTTN are associated with significant psychosocial burden and reduced HRQoL, indicating a need to develop effective treatments for neuropathic orofacial pain that target functional restoration.

Endoscopic Infraorbital Microdissection for Localized V2 Trigeminal Neuralgia

Trigeminal neuralgia is a chronic and debilitating syndrome characterized by short paroxysms of lancinating facial pain. Patients may be medically managed; however, in cases of medically refractory trigeminal neuralgia, surgical management is often required. Our objective was to present and describe a technique for endoscopic microdissection of the infraorbital nerve, a peripheral method of management for refractory V2 trigeminal neuralgia in patients without evidence of neurovascular compression. The technique is designed to spare sensation in unaffected portions of the V2 distribution. We present 2 patients with medically refractory V2 trigeminal neuralgia localized to the lateral midface who underwent infraorbital microdissection. After first confirming that there was no neurovascular compression on imaging in these patients, we administered infraorbital bupivacaine injections to localize the symptomatic nerve. The nerve was then accessed via a 1.5-cm buccogingival incision, and the connective tissue sheath was incised. The nerve fascicles were bluntly separated, and the symptomatic branches were cauterized with fine-tipped monopolar cautery. Both patients reported complete resolution of their pain postoperatively and were pain free at last follow-up. They reported some hypoesthesia in the lateral face; however, they retained some sensation in the medial upper lip, midface, and nose. Infraorbital microdissection is a safe and effective technique for symptomatic management of V2 trigeminal neuralgia while sparing sensation in asymptomatic portions of the dermatome.

Sphenopalatine Ganglion Block with Botulinum Neurotoxin for Treating Trigeminal Neuralgia Using CAD/CAM-Derived Injection Guide

AIMS

To examine the effectiveness and safety of using a CAD/CAM-derived injection guide for botulinum neurotoxin block of the sphenopalatine ganglion for trigeminal neuralgia treatment.

METHODS

Ten patients with second-division trigeminal neuralgia who did not respond to submucosal administration of botulinum neurotoxin were enrolled in this study. The target point around the sphenopalatine fossa was determined after fusion of computed tomography data with a scan of a maxillary model using a software program for dental implant surgery. A CAD/CAM-derived injection guide was fabricated. The guide was affixed to the patient's maxilla, and a needle was inserted to an exactly analyzed depth. Subsequently, 50 units of botulinum neurotoxin were injected. Pain intensity evaluated using a visual analog scale and pain frequency were measured.

RESULTS

By using the guides, sphenopalatine ganglion block with botulinum toxin was performed 18 times without any complications. The visual analog scale score (8.1 ± 1.0) and pain frequency (19.4 ± 8.8 times/day) decreased (to 1.9 ± 1.4 and 4.9 ± 5.4 times/day, respectively) significantly (P < .001). After 4 weeks, the mean subjective improvement achieved was 77.5% ± 13.8%, and all patients responded to treatment.

CONCLUSION

Even without prior experience of sphenopalatine ganglion block, the CAD/CAM-derived guide enabled the accurate and safe administration of botulinum neurotoxin to the sphenopalatine ganglion for the treatment of trigeminal neuralgia.

Minimally Invasive Trigeminal Ablation: Long Buccal Nerve

AIMS

To describe a technique of minimally invasive trigeminal nerve ablation of the long buccal nerve that was performed at a tertiary care academic medical center.

METHODS

This case describes a 44-year-old woman with refractory left long buccal nerve neuropathy following a dental procedure. After failing medical management, she was taken for nerve exploration, which revealed no nerve discontinuity or neuroma formation. She was therefore counseled regarding the risks and possible benefits of a novel minimally invasive trigeminal nerve thermoablation of the long buccal nerve technique.

RESULTS

Postoperatively, the patient experienced mild anesthesia along the long buccal nerve division and no longer experiences any allodynia or hypersensitivity. Additionally, she no longer requires any additional medical therapy or interventions.

CONCLUSION

Minimally invasive trigeminal nerve ablation of the long buccal nerve may be effective surgical intervention in treating refractory neuropathic pain in cases of no structural nerve defects. However, long-term well-designed studies are required to fully define its role.

Effects of surgical treatment for classical trigeminal neuralgia with concomitant persistent facial pain

PURPOSE

Classical trigeminal neuralgia with concomitant persistent facial pain responds poorly to conservative treatment. The authors describe the effects of microvascular decompression and radiofrequency thermocoagulation for patients with classical trigeminal neuralgia and concomitant persistent facial pain.

CASE REPORT

Case 1 was a 61-year-old man with dull, continuous, aching pain in the left maxillary and mandibular molar area. Case 2 was a 68-year-old woman with aching pain in the maxillary right molar. Case 3 was a 67-year-old woman with severe pain in the right upper lip and maxillary right second premolar. Case 4 was a 42-year-old man with orofacial pain of 14 months' duration. Cases 1 and 2 underwent radiofrequency thermocoagulation and reported good relief of symptoms. Cases 3 and 4 underwent microvascular decompression and attained excellent relief.

CONCLUSION

Microvascular decompression may be more effective than radiofrequency thermocoagulation for patients with classical trigeminal neuralgia with concomitant persistent facial pain.

[Anatomical rationale for surgical treatment of trigeminal neuralgia combined with cerebellopontine angle tumors]

Trigeminal neuralgia (TN) can be combined with tumors of the cerebellopontine angle (CPA). The optimal surgical management in these cases depends on the anatomical relationship of the trigeminal nerve root (TNR) with tumors and vessels. The purpose of this study is to evaluate variants of the anatomical relationship between the TNR and the surrounding structures as well as to analyze the results of using various surgical techniques for treatment of TN in CPA tumors.

MATERIAL AND METHODS

We performed a retrospective analysis of 51 patients (38 females and 13 males aged 22 to 77 years) with TN and ipsilateral CPA tumors. Space-occupying lesions were represented by 29 meningiomas of the petrous apex, 11 epidermoids, 9 vestibular schwannomas, 1 hemangioma, and 1 cavernoma.

RESULTS

Intraoperatively, we identified 6 types of the anatomical relationships among the TNR, tumors, and CPA vessels: type I - the TNR is completely surrounded by the tumor (4 epidermoids); type II - the tumor compresses and displaces the TNR (21 meningiomas, 4 schwannomas, and 6 epidermoids); type III - the tumor occurs inside the TNR (1 cavernoma); type IV - the tumor together with the vessel compresses the TNR (3 meningiomas and 1 epidermoid); type V - the tumor displaces the TNR towards the vessel (5 meningiomas and 5 schwannomas); type VI - the tumor does not contact the TNR that is compressed by the vessel (1 hemangioma). Preoperative MRI and intraoperative findings revealed compression and deformity of the brain stem at the TNR entry level in all but two patients. Vascular compression of the TNR (usually by the superior cerebellar artery) was found in 15 of 51 patients. Microvascular decompression (MVD) was performed using various techniques: interposition of implants between vessels and the TNR, transposition of the compressing vessels from the TNR, or transposition of the nerve root. In all patients, except 1, pain syndrome regressed immediately after tumor removal and MVD. In 1 case, the pain syndrome did not regress after total removal of epidermoid and MVD, and TN was resolved by percutaneous radiofrequency rhizotomy. Long-term postoperative follow-up results showed complete elimination of TN in all cases; there were no persistent neurological complications and postoperative mortality.

CONCLUSION

TN may result from direct compression and deformation of the TNR and brain stem by CPA tumors. In some cases, the cause of TN is combined compression of the TNR by the tumor and vessels. Assessment of the neurovascular relationships requires detailed examination of the entire TNR after tumor removal. In the case of vascular compression of the TNR, various MVD techniques can be used for treatment of TN.

[Experimental study of a new animal model with trigeminal neuralgia produced by administration of talc to peripheral infraobital nerve in rats]

PURPOSE

To establish a new animal model of trigeminal neuralgia（TN） produced by administration of talc to peripheral infraobital nerve in rats.

METHODS

Thirty male Wistar rats were randomly divided into 2 groups. Talcum powder (30％,0.3 mL) was injected into the peripheral infraorbital foramen in one group, the same dose of normal saline was injected by the same method in another group. On 3 day before surgery and 3 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 6 weeks, 8 and 12 weeks postoperatively, mechanical pain behavior was determined. Statistical analysis of the threshold of pain response was performed and the behavior of pain was observed in the area of infraorbital nerve innervation in rats. Histopathological changes of the peripheral infraorbital nerve tissue in the rats were observed 3 days, 4 weeks, 8 weeks and 12 weeks postoperatively. The expression of inflammatory factors such as tumor necrosis factor-α (TNF-α) and interleukin -1β (IL-1β) in the territory of the infraorbital nerve was detected by immunohistochemistry. SPSS16.0 software package was used to analyze the data.

RESULTS

The mechanical pain threshold of rats in the infraorbital innervation area 3 days postoperatively in the experimental group was significantly decreased compared with that in the preoperative group and the control group (P<0.01). The rats in the experimental group 3 days postoperatively experienced symptoms of irritability, scratching the face or aggressive behavior. Twelve weeks after operation, the mechanical pain threshold was still significantly decreased. Histopathological examination in the experimental group 3 days postoperatively mainly showed inflammation with a few inflammatory factors（IL-1β and TNF-α）expression. Inflammation in the experimental group 1week postoperatively was more intense and more inflammatory factors were expressed. Four weeks postoperatively, there was more proliferation of granulation tissue in the area of peripheral infraorbital nerve tissue and expression of inflammatory factors was highest. Four to twelve weeks, the inflammatory response in the experimental group was gradually reduced, increased scar and infraorbital nerve compressing by scar were observed, and the expression of inflammatory factors decreased gradually.

CONCLUSIONS

Injection of talc to the peripheral infraorbital foramen can establish a reliable and stable animal model for research of etiology and treatment of TN.

Subtle Sensory Abnormalities Detected by Quantitative Sensory Testing in Patients with Trigeminal Neuralgia

BACKGROUND

Trigeminal neuralgia (TN) is characterized by paroxysmal pain attacks affecting the somatosensory distributions of the trigeminal nerve. It is thought to be associated with a neurovascular conflict most frequently, but pathomechanisms have not been fully elucidated. In general, no sensory deficit is found in routine clinical examination. There is limited data available, however, showing subtle subclinical sensory deficits upon extensive testing.

OBJECTIVE

We used quantitative sensory testing (QST) to detect abnormalities in sensory processing in patients with TN by comparing the affected and non-affected nerve branches with their contralateral counterparts and by comparing the results of the patients with those of controls.

STUDY DESIGN

Observational study.

SETTING

University Hospital, Departments of Neurosurgery, Institute for Cognitive and Clinical Neuroscience.

METHODS

QST was conducted on 48 patients with idiopathic TN and 27 controls matched for age and gender using the standardized protocol of the German Neuropathic Pain Network. Stimulations were performed bilaterally in the distribution of the trigeminal branches. The patients had no prior invasive treatment, and medications at the time of examination were noted.

RESULTS

In patients with TN deficits in warm and cold sensory detection thresholds in the affected and also the non-affected nerve branches were found. Tactile sensation thresholds were elevated in the involved nerve branches compared to the contralateral side.

LIMITATIONS

More data are needed on the correlation of such findings with the length of history of TN and with changes of the morphology of the trigeminal nerve.

CONCLUSIONS

QST shows subtle sensory abnormalities in patients with TN despite not being detected in routine clinical examination. Our data may provide a basis for further research on the development of TN and also on improvement after treatment.

KEY WORDS

Quantitative sensory testing, trigeminal neuralgia, facial pain, neuropathic pain, microvascular decompression, cranial nerve.

[Evaluation of therapeutic effectiveness and safety of botulinum toxin type A in the treatment of idiopathic trigeminal neuralgia in patients older than 70 years]

OBJECTIVE

To evaluate therapeutic effectiveness and safety of botulinum toxin type A in the treatment of idiopathic trigeminal neuralgia in patients older than 70 years.

METHODS

The total 64 patents were involved from neurology clinic and inpatient department from Aug 2008 to Sep 2013. They were divided into two groups according to the age (older than 70 years versus younger than 60 years. The therapeutic dose, safety, effectiveness were compared between two groups. Visual analog scores were employed to measure the degree of pain.

RESULTS

The mean dosage was (88 ± 30) U in the group aged above 70 years old, and (72 ± 33) U in the group aged below 60 years old respectively. There was no significant difference of dosage between the two groups. The average visual analog score of all patients was (7.7 ± 2.2) before the treatment and decreased to (4.4 ± 2.9) one month after the treatment. To be precise, the average visual analog score of the group aged above 70 years old was (8.2 ± 1.9) before and (4.5 ± 3.2) after the treatment, and the visual analog score of the group aged below 60 years old was (7.2 ± 2.4) before and (4.4 ± 2.5) after the treatment. The effect of botulinum toxin type A in the treatment of idiopathic trigeminal neuralgia was considered statistically significant. The D-value of visual analog score in the elderly group was (3.5 ± 3.6), and (2.8 ± 3.5) in the younger group. There was no significant difference in the D-value between the two groups. Five patients had transient minor side effects in the former group and two patients had transient minor side effects in latter group. There was no significant difference in the incidence rate of side effects between the two groups (P > 0.05).

CONCLUSIONS

Botulinum toxin type A is safe and effective in the treatment of idiopathic trigeminal neuralgia for the patients older than 70 years and the dosages of it are approximate to the patients under 60 years old.

[Alarming effect of intraoperative neuroelectrophysiological monitoring in microvascular decompression for primary trigeminal neuralgia]

OBJECTIVE

To explore the alarming effect of intraoperative neuroelectrophysiological monitoring in microvascular decompression (MVD) for primary trigeminal neuralgia.

METHODS

In 2014, a total of 44 patients with an initial diagnosis of primary trigeminal neuralgia were consecutively recruited for surgery. And 41 of them with an intraoperative confirmation of primary trigeminal neuralgia underwent MVD. Intraoperative neuroelectrophysiological monitoring was employed for brainstem auditory evoked potentials (BAEPs), spontaneous electromyogram for obicularis oculi, obicularisoris and masseter muscles. The real-time alarming report was offered to the operator who adjusted operations accordingly.

RESULTS

There were abnormal changes in 23 cases (56.10%) with a total of 77 instances (BAEPs 27, trigeminal nerve 32, facial nerve 18). The outcomes were no facial pain (n=26), pain relief (n=15) and facial numbness (n=6, two with concurrent hearing disturbance). And the rates of facial pain disappearance and sequela occurrence were much better than those in controls without monitoring.

CONCLUSION

Intraoperative neuroelectrophysiological monitoring helps enhance the MVD effect and decrease operative squela through alarming reporting.

[Changes in pain threshold and glial cell line-derived neurotrophic factor in rat model of trigeminal neuralgia]

OBJECTIVE

This research aims to study the changes in pain threshold and glial cell line-derived neurotrophic factor (GDNF) in a Sprague Dawley (SD) rat model oftrigeminal neuralgia.

METHODS

A total of 36 male SD rats were randomly divided into three groups: operative, sham-operative, and control. In the operative group, a chronic constriction injury (CCI) was caused by placing loose chromic gut ligatures around the right infraorbital nerve (ION). In the sham-operative group, the right ION was subjected to the same procedure, but without ligation. In the control group, the right ION was not subjected to any treatment. The pain thresholds of the three groups were recorded at different times after the operation. The GDNF expression in each group was analyzed via immunohistochemical staining.

RESULTS

An allodynia to mechanical stimulation in the region of the ligated ION was observed starting on the 2nd week after operation. Pain thresholds started to increase gradually from the 6th week and returned to the original level at the 10th to 12th week after operation. Cells that expressed the GDNF markedly increased in number in the operative group with changes observed at different times.

CONCLUSION

We use chronic constriction injury to the infraorbital nerve (CCI-ION) to establish a trigeminal neuralgia-like animal model in SD rats. GDNF may play a role in regulating pain by promoting the restoration and regeneration of nerve fibers.

[Controlled clinical study of trigeminal ganglion puncture guided by CT/MRI image fusion interface navigation]

OBJECTIVE

To build the radio-frequency thermocoagulation (RFT) interface under navigation including foramen ovale and trigeminal ganglion based on CT/MRI image fusion technology, to visualize the relationship between the trigeminal ganglion and the puncture needle, and to observe clinical effects of this method.

METHODS

CT and MRI data of 20 trigeminal neuralgia patients which were input into BrainLAB-iPlan navigation planning system, were aligned and merged, so that the 3-dimentional image fusion interface of CT and MRI for puncture was built. According to the image fusion interface, the pathways targeting the trigeminal ganglion were planned to assist trigeminal ganglion puncture and RFT. The treatment consequences were observed and compared with 20 patients under the RFT only with the direction of pre- and intra-operative CT.

RESULTS

In the group of CT/MRI image fusion cases, 3 cases had been predicted to be difficult because of unreachable ganglion through the foramen ovale pathway. The postoperative clinical examination proved that the ganglions of these 3 cases were only insufficiently damaged or undamaged. The other 17 cases proved better results, except 2 cases whose treatment was changed in operation. The valid rates for both image fusion navigation group and CT group were all above 95%.

CONCLUSION

Navigation interface including both foramen ovale and trigeminal ganglion based on CT/MRI image fusion made visualization of the pathway targeting ganglion come true, which made the treatment more accurate and individual. Whether the pathway could reach the ganglion might distinguish the trouble cases from others.