Anatomie et neuro-imagerie de la névralgie trigéminale

The trigeminal nerve is the largest and most complex of the 12 cranial nerves. It supplies sensations to the face, mucous membranes, and other structures of the head. It is the motor nerve for the muscles of mastication and contains proprioceptive fibers. It exits the brain by a large sensory root and a smaller motor root coming out of the pons at its junction with the middle cerebral peduncle. It passes laterally to join the Gasserian (semilunar) ganglion in the Meckel cave. Trigeminal neuralgia (TN) is a debilitating facial pain disorder, frequently caused by vascular compression of the trigeminal nerve. The most frequent cause of TN is a mechanical irritation of the nerve caused by neurovascular contact, the neurovascular compression syndrome (NVCS). It is widely believed that compression in the socalled root entry or exit zone of the nerve causes NVCS. Most investigators define the root entry or exit zone as the region extending from the nerve’s point of entry into or exit from the brainstem to the point of transition from the central myelin (oligodendroglia) to the peripheral myelin (Schwann cells). The superior cerebellar artery is responsible for most cases of NVCS. Imaging combined with clinical information is critical to correctly identify patients who are candidates for microvascular decompression. We review trigeminal nerve anatomy and propose to recognize important magnetic resonance imaging findings in patients with trigeminal neuralgia.     

Increased HCN Channel Activity in the Gasserian Ganglion Contributes to Trigeminal Neuropathic Pain

Orofacial neuropathic pain caused by trigeminal nerve injury is a debilitating condition with limited therapeutic options. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels regulate neuronal excitability and are involved in the development and maintenance of chronic pain. However, the effect of HCN channel activity in the Gasserian ganglion on trigeminal neuropathic pain has not been examined. We evaluated nociceptive behaviors after microinjection of the HCN channel blockers ZD7288 or ivabradine into the Gasserian ganglion in rats with trigeminal nerve injury. Both blockers dose-dependently ameliorated evoked and spontaneous nociceptive behavior in rats with trigeminal neuropathic pain. Moreover, the clinically available HCN channel blocker ivabradine showed a prolonged antinociceptive effect. In the Gasserian ganglion, HCN1 and HCN2 are major HCN isoforms. After trigeminal nerve injury, the counts of HCN1 as well as HCN2 immuno-positive punctae were increased in the ipsilateral Gasserian ganglions. These results indicate that the increased HCN channel activity in the Gasserian ganglion directly contributes to neuropathic pain resulting from trigeminal nerve injury.

Comparison of High‐voltage‐ with Standard‐voltage Pulsed Radiofrequency of Gasserian Ganglion in the Treatment of Idiopathic Trigeminal Neuralgia

Although pulsed radiofrequency treatment (PRFT) has been used to treat trigeminal neuralgia (TN) safely, satisfactory improvement is lacking. Recently, much attention has been paid to the PRFT dose and intra‐operative parameters. It has been reported that high‐voltage PRFT could significantly reduce discogenic pain. However, there is no study investigating the effects of high‐voltage PRFT on TN. The aim of this prospective, randomized, double‐blinded study was to evaluate the efficacy and safety of high‐voltage PRFT in comparison with standard‐voltage PRFT for idiopathic TN. Sixty severe TN patients were randomly assigned to 2 groups treated with CT‐guided standard‐ or high‐voltage‐pulsed radiofrequency (RF) of Gasserian ganglion, respectively, between January 2012 and July 2012. Numeric Rating Scales (NRS), carbamazepine dose, and side effects were evaluated at day 1, weeks 1 and 2, months 1, 3, and 6, and 1 year postoperative. There were 27 patients in the standard‐voltage group and 26 patients in the high‐voltage group who completed the 1‐year follow‐up study. The effective rates in the standard‐voltage and high‐voltage PRFT groups were 41% and 69%, respectively, at 1, 3, and 6 months postoperative (P = 0.037). The effective rate in the standard‐voltage group decreased to 19% at 1‐year postoperative, while in the high‐voltage group remained at 69% (P = 0.000). No significant side effects were detected in both groups. In conclusion, CT‐guided high‐voltage PRFT is an effective and safe interventional therapeutic choice for idiopathic TN patients.     

The development of a technique for radiofrequency lesioning of splanchnic nerves

This article describes the development of a technique for radiofrequency lesioning of the splanchnic nerves. It features point neurolysis and improvement in safety from previously described techniques with the use of a curved, blunt needle. After extensive anatomic studies, the site of entry has been identified 4 cm lateral to the spinous process at the costovertebral angle of either the T11 or T12 vertebral body, and the placement of the needle tip at the junction of posterior two thirds to the anterior one third of the vertebral body. The use of a sharp, straight needle has been discouraged to prevent pneumothorax, and bowel, kidney, or nerve root injury. The radiofrequency lesion permits a point neurolysis, thus decreasing the rate of complications. Our experience of 22 patients treated with this technique has been complication-free, and the outcome was effective for all 10 patients with cancer. In the nonmalignancy group, some patients needed a second neurolysis (radiofrequency) procedure 4 months apart. There were also no secondary complications in these patients. We expect multicenter data accumulation in the coming years, which will determine the true efficacy of the radiofrequency of splanchnic nerves.     

Trigeminal Neuralgia in Pregnancy: A Management Challenge

Pregnancy is known to aggravate pre‐existing chronic painful conditions. Trigeminal neuralgia (TN), albeit a disease of the elderly, may afflict pregnant females, which can further complicate its management. Teratogenic effects of the commonly used drugs on the developing fetus limit pharmacological treatment. Moreover, safety of commonly performed interventional therapies is marred by their inherent fetomaternal effects and more importantly the risk for radiation effects on the fetus due to the use of fluoroscopy. This rare coexistence of TN in pregnancy has not been reported before. Here we present a case of TN in a young woman, whose pain was aggravated when she became pregnant, and she was treated successfully by conventional radiofrequency ablation of the Gasserian ganglion.     

3D CT‐Guided Pulsed Radiofrequency Treatment for Trigeminal Neuralgia

Trigeminal neuralgia (TN) is a pain syndrome characterized by pain in the trigeminal area often accompanied by a brief facial spasm or tic. The purpose of our study was to investigate the efficacy and clinical utility of CT‐guided pulsed radiofrequency (PRF) for treatment of TN. Patients who were diagnosed with severe TN between September 2010 and October 2010 at Beijing Tiantan Hospital were included. Pulsed radiofrequency treatment (PRFT) was employed to treat TN. To verify the accurate needle position, a thin‐section cranial CT scan was performed by using a multidetector CT scanner. Three‐dimensional reconstruction was performed to visualize the location of the needle and the foramen ovale. A total of 20 patients were included in the study. Seven patients (35%) had favorable outcome 1 year after the PRFT. The numeric rating scale in the 7 patients with good outcome was significantly lower than the 13 patients with bad outcome at 1 day, 1 week, and 2 weeks after the treatment. The remaining 13 patients had residual pain 2 weeks after the PRFT and had to receive radiofrequency thermocoagulation (RFTC). In conclusion, the results of our study demonstrate that CT‐guided PRFT is not an effective method of pain treatment for idiopathic TN as compared with conventional RFTC. However, CT‐guided PRFT is associated with less complication than RFTC.     

Gamma Knife Stereotactic Radiosurgery in the Management of Cluster Headache

Gamma knife stereotactic radiosurgery (SRS) has proven to be an effective management approach for trigeminal neuralgia and as a minimally invasive alternative management option for cluster headache (CH). In CH, patients undergo single-session focused irradiation of the trigeminal nerve root (TN), sometimes coupled with irradiation of the sphenopalatine ganglion (SPG) as well. SRS provides early pain relief in most patients, but is associated with trigeminal sensory dysfunction in some patients. In the future, a prospective trial that compares a single target of TN to dual targets of both the TN and SPG may provide further understanding of the value of SRS for CH.     

Comparison of clinical symptoms and magnetic resonance angiographic (MRA) results in patients with trigeminal neuralgia and persistent idiopathic facial pain. Medium-term outcome after microvascular decompression of cases with positive MRA findings

Neurovascular compression (NC) seems to have been confirmed as the major cause of classical trigeminal neuralgia (TN). In spite of the large number of surgically positive cases, however, there are still cases where no vascular compression of the trigeminal nerve can be found. To evaluate whether NC could be demonstrated preoperatively, high-resolution magnetic resonance angiography (MRA) was performed in 287 consecutive patients with TN and persistent idiopathic facial pain (PIFP) on a 0.5-T and a 1-T MR unit. Depending on the clinical symptoms, the TN cases were divided into typical TN and trigeminal neuralgia with non-neuralgic interparoxysmal pain (TNWIP) groups. Microvascular decompression (MVD) was performed in 103 of the MRA-positive cases. The patients were followed up postoperatively for from 1 to 10 years. The clinical symptoms were compared with the imaging results. The value of MRA was assessed on the basis of the clinical symptoms and surgical findings. The outcome of MVD was graded as excellent, good or poor. The clinical symptoms were compared with the type of vascular compression and the outcome of MVD. The MRA image was positive in 161 (56%) of the 287 cases. There were significant differences between the clinical groups: 66.5% of the typical TN group, 47.5% of the TNWIP group and 3.4% of the PIFP group were positive. The quality of the MR unit significantly determined the ratio of positive/negative MRA results. The surgical findings corresponded with the MRA images. Six patients from the MRA-negative group were operated on for selective rhizotomy and no NC was found. Venous compression of the trigeminal nerve was observed in a significantly higher proportion in the background of TNWIP than in that of typical TN on MRA imaging (24.1% and 0.8%, respectively) and also during MVD (31.2% and 1.2%, respectively). Four years following the MVD, 69% of the patients gave an excellent, 23% a good and 8% a poor result. The rate of some kind of recurrence of pain was 20% in the typical TN and 44% in TNWIP group. The rate of recurrence was 57% when pure venous compression was present. The only patient who was operated on from the PIFP group did not react to the MVD. The clinical symptoms and preoperative MRA performed by at least a 1-T MR unit furnish considerable information, which can play a role in the planning of the treatment of TN.     

Trigeminal neuralgia and pain related to multiple sclerosis

Although many patients with multiple sclerosis (MS) complain of trigeminal neuralgia (TN), its cause and mechanisms are still debatable. In a multicentre controlled study, we collected 130 patients with MS: 50 patients with TN, 30 patients with trigeminal sensory disturbances other than TN (ongoing pain, dysaesthesia, or hypoesthesia), and 50 control patients. All patients underwent pain assessment, trigeminal reflex testing, and dedicated MRI scans. The MRI scans were imported and normalised into a voxel-based, 3D brainstem model that allows spatial statistical analysis. The onset ages of MS and trigeminal symptoms were significantly older in the TN group. The frequency histogram of onset age for the TN group showed that many patients fell in the age range of classic TN. Most patients in TN and non-TN groups had abnormal trigeminal reflexes. In the TN group, 3D brainstem analysis showed an area of strong probability of lesion (P < 0.0001) centred on the intrapontine trigeminal primary afferents. In the non-TN group, brainstem lesions were more scattered, with the highest probability for lesions (P < 0.001) in a region involving the subnucleus oralis of the spinal trigeminal complex. We conclude that the most likely cause of MS-related TN is a pontine plaque damaging the primary afferents. Nevertheless, in some patients a neurovascular contact may act as a concurring mechanism. The other sensory disturbances, including ongoing pain and dysaesthesia, may arise from damage to the second-order neurons in the spinal trigeminal complex.     

Abnormal trigeminal nerve microstructure and brain white matter in idiopathic trigeminal neuralgia

Idiopathic trigeminal neuralgia (TN) is classically associated with neurovascular compression (NVC) of the trigeminal nerve at the root entry zone (REZ), but NVC-induced structural alterations are not always apparent on conventional imaging. Previous studies report lower fractional anisotropy (FA) in the affected trigeminal nerves of TN patients using diffusion tensor imaging (DTI). However, it is not known if TN patients have trigeminal nerve abnormalities of mean, radial, or axial diffusivity (MD, RD, AD – metrics linked to neuroinflammation and edema) or brain white matter (WM) abnormalities. DTI scans in 18 right-sided TN patients and 18 healthy controls were retrospectively analyzed to extract FA, RD, AD, and MD from the trigeminal nerve REZ, and Tract-Based Spatial Statistics (TBSS) was used to assess brain WM. In patients, the affected trigeminal nerve had lower FA, and higher RD, AD, and MD was found bilaterally compared to controls. Group TBSS (P < 0.05, corrected) showed patients had lower FA and increased RD, MD, and AD in brain WM connecting areas involved in the sensory and cognitive-affective dimensions of pain, attention, and motor functions, including the corpus callosum, cingulum, posterior corona radiata, and superior longitudinal fasciculus. These data indicate that TN patients have abnormal tissue microstructure in their affected trigeminal nerves, and as a possible consequence, WM microstructural alterations in the brain. These findings suggest that trigeminal nerve structural abnormalities occur in TN, even if not apparent on gross imaging. Furthermore, MD and RD findings suggest that neuroinflammation and edema may contribute to TN pathophysiology.     

1. Trigeminal Neuralgia

Trigeminal neuralgia is a common cause of facial pain. It has a significant impact on the quality of life and the socioeconomic functioning of the patient. The aim of this review is to provide recommendations for medical management of trigeminal neuralgia based on current evidence. Based upon the analyses of the literature combined with experience in pain management, symptoms, assessment, differential diagnosis, and treatment possibilities of trigeminal neuralgia are described and discussed. Recommendations for pain management are given and are displayed in a clinical practice algorithm. Treatment should be multidisciplinary. Various treatment options and their risks should be discussed with the patient. The first treatment of choice is carbamazepine or oxcarbazepine. In younger patients, the first choice of invasive treatment is probably microvascular decompression. For elderly patients, radiofrequency treatment of Gasserian ganglion is recommended and the technique is described in detail.     

Chronic Stimulation of the Gasserian Ganglion for Treatment of Atypical Facial Neuralgia

After a trial of percutaneous stimulation of the Gasserian ganglion in 21 patients with atypical facial pain, five patients were selected for chronic implantation. After a follow-up of two years (18 to 32 months), there is stable and excellent analgesia in three patients. There are various complications and problems associated with the method of implantation, either percutaneous or open. The best indication for this procedure is the presence of trigeminal pain and some sensory loss in the painful area. This new application of neurostimulation for pain was described by Myerson in 1980, and this therapy should be considered for any patient who has atypical facial pain that has been resistant to other forms of treatment.     

Increased CSF Levels of Apolipoproteins and Complement Factors in Trigeminal Neuralgia Patients–In Depth Proteomic Analysis Using Mass Spectrometry

The main cause of trigeminal neuralgia (TN) is compression of a blood vessel at the root entry zone of the trigeminal nerve. However, a neurovascular conflict does not seem to be the only etiology and other mechanisms are implicated in the development of the disease. We hypothesized that TN patients may have distinct protein expression in the CSF. In this study, lumbar CSF from TN patients (n = 17), scheduled to undergo microvascular decompression, and from controls (n = 20) was analyzed and compared with in depth mass spectrometry TMTbased quantitative proteomics. We identified 2552 unique proteins, of which 46 were significantly altered (26 increased, and 20 decreased, q-value < .05) in TN patients compared with controls. An over-representation analysis showed proteins involved in high-density lipoprotein, such as Apolipoprotein A4, Apolipoprotein M, and Apolipoprotein A1, and the extracellular region, including proteins involved in the complement cascade to be over-represented. We conclude that TN patients have distinct protein expression in the CSF compared to controls. The pathophysiological background of the protein alterations found in this study warrants further investigation in future studies.PerspectiveIn this article, cerebrospinal fluid from patients with trigeminal neuralgia was analyzed using in depth shotgun proteomics, revealing 46 differentially expressed proteins compared to controls. Among these, apolipoproteins and proteins involved in the complement system were elevated and significantly over-represented, implying an inflammatory component in the pathophysiology of the disease.     

Percutaneous balloon compression for trigeminal neuralgias and autonomic cephalalgia

OBJECTIVE: This prospective study aimed to evaluate the results of percutaneous trigeminal ganglion balloon compression (BC) in patients with various types of trigeminal neuralgia (TN) and autonomic cephalalgia. METHODS: Twenty-five consecutive patients underwent BC and were followed up for 27-60 months. They were divided into 2 groups: group A (n=18) patients with idiopathic TN and group B (n=7) patients with secondary TN (n=5) and trigeminal autonomic cephalalgia (TAC) (n=2). RESULTS: Postoperatively, 15 patients in group A experienced pain relief, one required medication and 2 had no response; in group B, 6 were free of pain, including the 2 patients with TAC, and one required medication. Complications in both groups were either functionally trivial or infrequent. None of the patients developed keratitis or anesthesia dolorosa. Pain recurrence occurred early (<6 months) in one patient from group B, and late in 2 patients from group A. CONCLUSION: Balloon compression is a minimally invasive procedure that seems to be comparably successful for idiopathic and secondary TN, as well as TAC. However, further studies are deemed necessary to establish it as the first-line treatment in medically resistant trigeminal pain.     

Prevalence of hypertension in patients with trigeminal neuralgia

It is unclear whether hypertension (HTN) is a predisposing factor for the development of trigeminal neuralgia (TN). The purpose of this study was to determine the prevalence of HTN in TN patients and controls at the USC Orofacial Pain and Oral Medicine Center. A retrospective chart review was conducted from a database of over 3,000 patient records from 2003 to 2007. We identified patients diagnosed with TN with or without HTN. A total of 84 patients (54 females; 30 males) between the ages of 33 and 93 years were diagnosed with TN; 37% had TN with HTN and 32% of controls had HTN. The increased prevalence of HTN in the TN patients was not statistically significant (P = 0.50). Since, both TN and HTN are seen in the elderly, it is likely that HTN is simply a co-existing condition in patients with TN and not a risk factor for its development.     

螺旋CT引导半月节脉冲射频治疗三又神经痛的远期疗效观察

目的 观察螺旋CT引导下半月节穿刺脉冲射频治疗三叉神经痛的远期疗效.方法 100例原发性三叉神经痛患者分为研究组(脉冲射频组,n=44)和对照组(射频热凝组,n=56).比较治疗前,治疗后0.5年、1年、2年时的疼痛数字模拟评分(NRS)及临床疗效.结果 治疗后1年内两组NRS无显著性差异,但2年后研究组复发率明显高于对照组(P＜0.01).结论 半月节脉冲射频治疗三叉神经痛安全有效,但远期疗效欠佳.     

Some considerations about the treatment of trigeminal neuralgia with intrathecal baclofen

A case history of therapy resistent trigeminal neuralgia was presented by Wechsung and Müller. This patient was previously treated without any succes with glycerol injections, "electrocauterisation", a Janetta operation and 2 reexplorations of the posterior fossa. Attempts with oral carbamazepine and baclofen were unsuccesful too. The authors did not try out the combination of carbamazepine and baclofen, which is recommended by Fromm and Terrence. When conservative treatment fails, surgical procedures are indicated. The most succesful surgical procedure is the radiofrequency thermal lesion of the Gasserian ganglion (Sweet). Data from the literature from 8500 patients and own data (from over 600 patients) show that therapy resistance is very infrequent (0.5%). The costs of clinical implantation of a pump with intrathecally administered baclofen are 10-15 times higher than ambulant radiofrequency lesioning.     

Erfahrungen mit der retroganglionären Glycerin-Rhizotomie in der Behandlung der Trigeminusneuralgie

From August 1981 to May 1993 a total of 1263 percutaneous retrogasserian glycerol rhizotomies after Hakanson were performed. The intervention was performed with X-ray monitoring under local anaesthesia and rarely lasted longer than 20 min. It achieved good results in the treatment of idiopathic trigeminal neuralgia (TN) and symptomatic trigeminal neuralgia due to multiple sclerosis (TNMS). Some 97% of the TN patients were completely free of pain after the intervention. The recurrence rate within 5 years was 12.8%. Some 94.7% of the TNMS patients were immediately free of pain, but within 2-5 years they experienced a high recurrence rate of 40.2%. The results in the patients with atypical facial pain were more disappointing: only 66.6% were pain-free immediately after the intervention, and the recurrence rate was 31%. With respect to the side effects immediately postoperatively, herpetic eruptions were found in 43.2% of cases. They occurred on the 3rd postoperative day and persisted for 2-3 weeks before being relieved by local virostatic therapy. Hypaesthesia and hypalgesia were present in the early postoperative follow-up in half of our patients. Both these reductions of sensitivity have a tendency to regress. Later, after 2 years, there was reduction in sensitivity of this type in only 20% of cases. In the follow-up 17.5% of our patients complained of dysaesthesia and in 21.4% corneal sensitivity was reduced or lost. We believe that glycerol rhizotomy, owing to its effectiveness, easy applicability, slight distress for the patients and low side effects, should be recommended as a first measure for non-conservative treatment of idiopathic trigeminal neuralgia as well as trigeminal neuralgia in multiple sclerosis.     

Activation of CamKIIα expressing neurons on ventrolateral periaqueductal gray improves behavioral hypersensitivity and thalamic discharge in a trigeminal neuralgia rat model

BackgroundPreceding studies have reported the association of chronic neuropathic orofacial pain with altered ongoing function in the ventrolateral periaqueductal gray (vlPAG). However, its role in trigeminal neuralgia (TN) lacks attention. We here reported the aspect that vlPAG neurons play in TN nociceptive processing by employing excitatory neuron-specific optogenetic approaches.MethodsTN was generated via unilateral infraorbital nerve chronic constriction in Sprague Dawley rats which induced mechanical and thermal pain sensitivity in air puff and acetone test, respectively. Channelrhodopsin conjugated virus with CamKIIα promoter was used to specifically activate the excitatory vlPAG neuronal population by optogenetic stimulation and in vivo microdialysis was done to determine its effect on the excitatory-inhibitory balance. In vivo extracellular recordings from ventral posteromedial (VPM) thalamus were assessed in response to vlPAG optogenetic stimulation. Depending on the experimental terms, unpaired student’s t test and two-way analysis of variance (ANOVA) were used for statistical analysis.ResultsWe observed that optogenetic activation of vlPAG subgroup neurons markedly improved pain hypersensitivity in reflexive behavior tests which was also evident on microdialysis analysis with increase glutamate concentration during stimulation period. Decreased mean firing and burst rates were evident in VPM thalamic electrophysiological recordings during the stimulation period. Overall, our results suggest the optogenetic activation of vlPAG excitatory neurons in a TN rat model has pain ameliorating effect.ConclusionsThis article presents the prospect of pain modulation in trigeminal pain pathway via optogenetic activation of vlPAG excitatory neurons in rat model. This outlook could potentially assist vlPAG insight and its optogenetic approach in trigeminal neuropathic pain which aid clinicians endeavoring towards enhanced pain relief therapy in trigeminal neuralgia patients.     

Classic trigeminal neuralgia: a surgical perspective.

Classic trigeminal neuralgia (TN) was described as early as the first century AD, when treatments ranged from bloodletting to the application of poison-laden bandages. Current medical treatment utilizes a variety of drug therapies. Surgery is reserved for those who are unable to tolerate the side effects or in situations in which the drugs prove to be ineffective. Surgical options include microvascular decompression, percutaneous balloon compression, radio-frequency thermocoagulation, and glycerol injection. Nurses play a critical role in the multidisciplinary care of patients undergoing surgical procedures for TN.