The anatomy of vascular compression in trigeminal neuralgia

Efficacy and safety of a third stereotactic radiosurgery for recurrent trigeminal neuralgia: an international, multicenter study

BACKGROUND AND OBJECTIVES

Trigeminal Neuralgia (TN) is a debilitating facial pain disorder, often necessitating surgical interventions when medication proves insufficient. Stereotactic Radiosurgery (SRS) is an established therapeutic option. Limited studies explored the feasibility of a third SRS procedure. Our study investigates the safety and efficacy of a third SRS procedure for recurrent TN.

METHODS

We performed a retrospective analysis across multiple centers using databases collected prospectively. Pain status was evaluated utilizing the BNI Pain Intensity Scales. The Kaplan-Meier method was employed to estimate the time to recurrence, with group comparisons conducted using log-rank tests. Associations were explored using Chi-square and logistic regression models.

RESULTS

Ten institutions contributed with a total of 35 patients. A third SRS revealed sustained effectiveness with a pain control rate of 82.7%. The median time to recurrence was 35.5 months. New sensory dysfunction following the third procedure occurred in 22% of patients who had preserved sensory function after the second procedure. When considering those who developed sensory dysfunction after the second procedure, 40% of the entire cohort was affected. There were no significant differences in pain recurrence intervals among the three procedures. A meta-analysis, combining data from previous studies, showed that 89.6% of patients achieved some degree of pain control after a third SRS, with 27.4% experiencing new sensory dysfunction and a median time to recurrence of 31.6 months.

CONCLUSION

Our study, the largest on the topic, affirms the sustained effectiveness of a third SRS for TN, providing comparable pain relief to initial procedures. Notably, an extended pain-free interval after the third SRS session was observed. Facial sensory dysfunction emerged as the primary side effect. Larger studies are warranted to explore correlations with demographics and treatment parameters for a comprehensive understanding of repeat SRS in managing recurrent TN.

[Surgical treatment of trigeminal pain]

Surgical procedures for treating neuropathic pain, including trigeminal neuralgia (TGN), are categorized into three groups: decompression, ablation, and neuromodulation. Microvascular decompression is the only causal therapy for TGN, applicable favorably in cases of classical TGN due to a vascular nerve conflict. Ablative procedures include both percutaneous and radiosurgical methods, which are mainly used for idiopathic trigeminal neuralgia. For irreversible neuropathies of the trigeminal nerve, the algorithm for other neuropathic pain conditions should be considered, along with the potential use of neuromodulatory techniques. When selecting a therapy, diagnosis, medication side effects, individual patient risks, and treatment outcomes must all be taken into account (current S1 guideline from the German Society of Neurology).

The Arterial Anatomy of the Cerebellum-A Comprehensive Review

The cerebellum, a major feature of the hindbrain, lies posterior to the pons and medulla and inferior to the posterior part of the cerebrum. It lies beneath the tentorium cerebelli in the posterior cranial fossa and consists of two lateral hemispheres connected by the vermis. The cerebellum is primarily supplied by three arteries originating from the vertebrobasilar system: the superior cerebellar artery (SCA), the anterior inferior cerebellar artery (AICA), and the posterior inferior cerebellar artery (PICA). However, variations of the cerebellar arteries may occur, such as duplication of the SCA, SCA creating a common trunk with the posterior cerebral artery, triplication of the AICA, and agenesis of PICA, amongst others. Knowledge of the arterial anatomy of the cerebellum is crucial, as inadequate blood supply to this region can result in diminished motor functioning, significantly impacting the quality of life for patients. The present study demonstrated the importance of adequate anatomical knowledge of the arteries supplying the cerebellum. The PubMed and Embase databases were searched to gather articles on the anatomical characteristics and variations of the arterial supply of the cerebellum. It is the most comprehensive and up-to-date review available in the literature. The possible variations of these vessels may be clinically silent or present with clinical symptoms such as neurovascular compression syndromes of the cranial nerves and aneurysms. With a comprehensive understanding of the cerebellar arterial system, physicians can enhance their diagnostic and treatment capabilities, ultimately leading to more effective management of cerebellar vascular-related issues and other neurological deficits.

Benchtop and in Vitro Experiments of Novel Transform Stents for Trigeminal Neuralgia Treatment

BACKGROUND

Trigeminal neuralgia (TN) is a debilitating condition characterized by sudden, excruciating facial pain due to neurovascular compression of the trigeminal nerve. Stent deployment can change the course of the superior cerebellar artery upwards, possibly releasing the root entry zone of the trigeminal nerve. We developed a novel stent, the Transform stent, for TN treatment, and evaluated its mechanical properties using benchtop and in vitro hemocompatibility tests.

METHODS

We compared the performance of Transform and Enterprise stents in treating TN because they share similar self-expanding closed-cell features in the manufacturing process, are derived from nitinol tubes, and are fabricated through a laser-cutting process, but also because only the safety of Enterprise stents deployed in intracranial arteries has been reported clinically. All benchtop measurements, including radial force, trackability, bending stiffness, and conformability, were performed thrice for each stent model, and their average values are presented.

RESULTS

Transform stents showed higher radial forces in vessels of diameters ranging from 1.0 mm than Enterprise stents. The trackability of the Transform stent was better than that of the Enterprise stent in a neurovascular model. Bending stiffness was stronger in the Transform stent whereas conformability was superior in the Enterprise stent. No significant thrombogenic issues were observed in the in vitro hemocompatibility tests.

CONCLUSIONS

This study demonstrated the Transform stent as a potential option and paved the way for innovative endovascular approaches for the future TN treatment. Namely, the study confirmed that the characteristics of Transform stents at benchtop and in vitro evaluations may be used as a first step for studies such as in vivo pre- and clinical studies.

Microvascular Decompression versus Radiofrequency Ablation in Trigeminal Neuralgia of the Maxillary and Mandibular Divisions

Background  Although medical treatment is the mainstay of therapy, in trigeminal neuralgia (TN), patients failing to respond to it make them candidates to ablative or nonablative procedures. Objective  The aim of this study was to compare the outcome of Microvascular decompression (MVD) and radiofrequency (RF) thermocoagulation in the management of TN affecting the mandibular and maxillary divisions. Materials and Methods  Retrospective analysis of the data of 40 patients suffering from intractable classical TN affecting the maxillary or mandibular divisions or both was carried out. Twenty patients were operated upon by MVD of the trigeminal nerve; and 20 had RF ablation of the maxillary or mandibular divisions of the trigeminal nerve or both. Results  In MVD the overall successful outcome was achieved in 16 patients (80%), while the failure was in 4 patients (20%) of which 3 had a fair outcome and 1 patient had a poor outcome. Whereas in RF the overall successful outcome was achieved in 17 patients (85%), while the failure was in 3 patients (15%) of which 2 had a fair outcome and 1 patient had a poor outcome. Outcome was insignificantly different between both groups ( p -value 0.806). Conclusion  MVD and RF ablation represent safe and efficacious surgical choices for addressing TN that encompasses both the mandibular and maxillary divisions. Long-term follow-up studies demonstrate that MVD consistently yields favorable outcomes, establishing it as the preferred primary surgical technique, unless contraindicated by the patient's general health and specific needs.

miRNA contributes to neuropathic pains

Neuropathic pain (NP) is a kind of chronic pain caused by direct injury to the peripheral or central nervous system (CNS). microRNAs (miRNAs) are small noncoding RNAs that mostly interact with the 3 untranslated region of messenger RNAs (mRNAs) to regulate the expression of multiple genes. NP is characterized by changes in the expression of receptors and mediators, and there is evidence that miRNAs may contribute to some of these alterations. In this review, we aimed to fully comprehend the connection between NP and miRNA; and also, to establish a link between neurology, biology, and dentistry. Studies have shown that targeting miRNAs may be an effective therapeutic strategy for the treatment of chronic pain and potential target for the prevention of NP.

Posterior Fossa Volume and Dimensions: Relation to Pathophysiology and Surgical Outcomes in Classic Trigeminal Neuralgia

OBJECTIVE

A small posterior fossa (PF) has been hypothesized to explain the increased incidence of trigeminal neuralgia (TN) in females and could make microvascular decompression (MVD) more challenging. The aim of this study was to investigate the association between the PF volume and dimensions in relation to biological sex, type of neurovascular conflict (NVC), and outcome after MVD in classic TN.

METHODS

In this observational study, 84 patients with TN operated on with MVD with a preoperative head computed tomography(CT) scan were included. Eighty-two adults without TN who had undergone head CT for other reasons were included as controls. PF volume and dimensions (x-axis, y-axis, and z-axis) were evaluated on the CT scans. For the patients with TN, Barrow Neurological Institute (BNI) grade was evaluated 6 months after MVD.

RESULTS

There was no difference in PF volume or dimensions between the patients with TN and controls. Women showed a smaller volume and narrower (x-axis) PF than men, but these differences did not manifest when comparing patients with TN and controls within each sex. Patients with an NVC involving the superior cerebellar artery had a narrower (x-axis) and shorter (y-axis) PF than did patients with an NVC resulting from other arteries. PF volume or dimensions were not associated with BNI grade after MVD.

CONCLUSIONS

PF anatomy was related to the NVC type but did not differ between patients with TN and controls and was not related to the surgical outcome after MVD.

Outcomes After Microvascular Decompression for Sole Arterial Versus Venous Compression in Trigeminal Neuralgia

OBJECTIVE

In most cases of trigeminal neuralgia (TN), the trigeminal nerve is compressed by the arterial vasculature. We sought to address the gap in understanding of pain outcomes in patients with sole arterial versus sole venous compression.

METHODS

We retrospectively reviewed all patients undergoing microvascular decompression at our institution, identifying patients with either sole arterial or venous compression. We dichotomized patients into arterial or venous groups and obtained demographics and postoperative complications for each case. Barrow Neurological Index (BNI) pain scores were collected preoperatively, postoperatively, and at final follow-up, as well as recurrence of pain. Differences were calculated via χ2 tests t tests, and Mann-Whitney U Tests. Ordinal regression was used to account for variables known to influence TN pain. Kaplan-Meier analysis was used to determine recurrence-free survival.

RESULTS

Of 1044 patients, 642 (61.5%) had either sole arterial or venous compression. Of these cases, 472 showed arterial compression and 170 showed sole venous compression. Patients in the venous compression group were significantly younger (P < 0.001). Patients with sole venous compression showed worse preoperative (P = 0.04) and final follow-up (P < 0.001) pain scores. Patients with sole venous compression had significantly higher rate of pain recurrence (P = 0.02) and BNI score at pain recurrence (P = 0.04). On ordinal regression, venous compression was found to independently predict worse BNI pain scores (odds ratio, 1.66; P = 0.003). Kaplan-Meier analysis showed a significant relationship between sole venous compression and increased risk of pain recurrence (P = 0.03).

CONCLUSIONS

Patients with TN with sole venous compression show worse pain outcomes after microvascular decompression compared with those with only arterial compression.

Cerebrospinal Fluid in Classical Trigeminal Neuralgia: An Exploratory Study on Candidate Biomarkers

Trigeminal neuralgia (TN) is a severe type of facial pain. A neurovascular conflict between cranial nerve V and a nearby vessel is the main pathophysiological mechanism, but additional factors are likely necessary to elicit TN. In this study, the primary aim was to explore differences in protein expression in the cerebrospinal fluid (CSF) of TN patients in relation to controls. Methods: Sixteen TN patients treated with microvascular decompression and 16 control patients undergoing spinal anesthesia for urological conditions were included. Lumbar CSF was collected preoperatively for the TN patients and before spinal anesthesia for the controls. A multiplexed proximity extension analysis of 91 CSF proteins was conducted using Proseek Multiplex Development 96, including biomarkers of cell communication, cell death, neurogenesis, and inflammation Results: The TN patients and the controls were of similar age, sex, and burden of co-morbidities. The TN patients exhibited higher concentrations of Clec11a, LGMN, MFG-E8, and ANGPTL-4 in CSF than the controls (q < 0.05). Conclusions: TN patients exhibited increased CSF biomarkers indicative of peripheral demyelinating injury (Clec11a), immune tolerance and destruction of myelin (LGMN), neuronal cell death (MFG-E8), and disturbances in myelin clearance (ANGPTL-8). Our findings are hypothesis-generating for candidate biomarkers and pathophysiological processes in classical TN.

Predictive and prognostic factors for outcome of microvascular decompression in trigeminal neuralgia

BACKGROUND

Trigeminal neuralgia (TN) is a disease characterized by recurring, short-lived, electric shock-like pain experienced on one side of the face. Microvascular decompression (MVD) is one of the most effective surgical interventions for resolving TN caused by neurovascular compression. This study aimed to determine the predictive and prognostic factors of surgical outcomes.

METHODS

This retrospective cohort study enrolled patients diagnosed with TN who underwent MVD at our hospital during 2013-2019. The demographic information, pain character, peri-operative Barrow Neurological Institute (BNI) scale, medication, operative finding were recorded. And the outcome was Outcomes were divided into drug-free and drug-dependent group. Predisposing factors for each outcome were analyzed by one-way analysis of variance, followed by a Mann-Whitney U test or Kruskal-Wallis test.

RESULTS

A total of 104 consecutive patients received MVD to treat TN, and 88 patients were enrolled in this study. The overall postoperative drug-free outcome was 72.7%. A significant difference in drug-free outcomes was observed for patients with typical TN (80.8%) compared with patients with atypical TN (33.33%, p = 0001). When severe venous compression was encountered during MVD, the drug-free outcome fell to 50% (10/20, p = 0.009). The Mann-Whitney U test indicated typical TN as a positive predictive factor of a drug-free outcome, whereas severe venous compression was a negative predictive factor. The patients with preoperative BNI score of 4 had better improvement than others (p = 0.045). Age, onset duration, and arterial loop had no specific difference in this study.

CONCLUSION

In our study, atypical TN and severe venous compression were associated with poor outcomes. Regrouping atypical TN into precise diagnosis represents an immediate priority according to our result. The preoperative BNI score could be used as an effective predictive tool for the outcome of MVD surgery.

Neurapraxia in patients with trigeminal neuralgia but no identifiable neurovascular conflict during microvascular decompression: a retrospective analysis of 26 cases

Background

Microvascular decompression (MVD) is the first choice in patients with classic trigeminal neuralgia (TGN) that could not be sufficiently controlled by pharmacological treatment. However, neurovascular conflict (NVC) could not be identified during MVD in all patients. To describe the efficacy and safety of treatment with aneurysm clips in these situations.

Methods

A total of 205 patients underwent MVD for classic TGN at our center from January 1, 2015 to December 31, 2019. In patients without identifiable NVC upon dissection of the entire trigeminal nerve root, neurapraxia was performed using a Yasargil temporary titanium aneurysm clip (force: 90 g) for 40 s (or a total of 60 s if the process must be suspended temporarily due to bradycardia or hypertension).

Results

A total of 26 patients (median age: 64 years; 15 women) underwent neurapraxia. Five out of the 26 patients received prior MVD but relapsed. Immediate complete pain relief was achieved in all 26 cases. Within a median follow-up of 3 years (range: 1.0–6.0), recurrence was noted in 3 cases (11.5%). Postoperative complications included hemifacial numbness, herpes labialis, masseter weakness; most were transient and dissipated within 3–6 months.

Conclusions

Neurapraxia using aneurysm clip is safe and effective in patients with classic TGN but no identifiable NVC during MVD. Whether this method could be developed into a standardizable method needs further investigation.

The Integrity of the Substructure of the Corpus Callosum in Patients With Right Classic Trigeminal Neuralgia

OBJECTIVE

Patients with classic trigeminal neuralgia (CTN) have abnormalities in white matter integrity of the corpus callosum (CC). However, in CTN patients, it is unclear whether the CC substructure region is affected to varying degrees.

MATERIAL AND METHODS

A total of 22 patients with CTN and 22 healthy controls (HC) with matching age, gender, and education were selected. All subjects underwent 3.0 T magnetic resonance diffusion tensor imaging and high resolution T1-weighted imaging. The CC was reconstructed by DTI technology, which was divided into three substructure regions: genu, body, and splenium. Group differences in multiple diffusion metrics, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD), were compared between CTN patients and HC, and correlations between the white matter change and disease duration and VAS in CTN patients were assessed.

RESULTS

Compared with HC group, CTN patients had extensive damage to the CC white matter. The FA of the genu (P = 0.04) and body (P = 001) parts decreased, while RD (P = 0.003; P = 0.02) and MD (P = 0.002; P = 0.04) increased. In addition, the authors observed that the disease duration and VAS of CTN patients were negatively correlated with FA.

CONCLUSION

The corpus callosum substructure region has extensive damage in chronic pain, and the selective microstructural integrity damage was particularly manifested by changes in axons and myelin sheath in the genu and body of corpus callosum.

In vitro and in vivo experiments of a novel intra-arterial neurovascular decompressor for treating neurovascular compression syndromes: a brief report

Objectives: Neurovascular compression syndromes (NVCS) could be cured with an intravascular device that releases compression of the root entry zone of cranial nerves by changing the course of offending vessels. The purpose of this study was to report our results of in vitro and in vivo experiments with a novel intra-arterial neurovascular decompressor (IA-NVD) for NVCS. Methods: A nitinol-based IA-NVD was developed to release pressure applied to the root entry zone of cranial nerves by changing the course or angle of an offending vessel, which can possibly cure NVCS. We performed in vitro tests for safety and feasibility and preliminary in vivo tests up to 4 weeks for safety. Results: The bending stiffness of the device was similar to but slightly stronger than that of current, closed-cell intracranial stents. Hemocompatibility tests showed no significant thrombogenesis in whole blood. After the 4-week follow-up, all animals (20-month-old female Gottingen mini-pigs weighing 15-18 kg, n = 4) had a normal upright position and gait. Scanning electron microscopy images and H&E staining of arteries containing the devices showed good neointima formation on the devices. Intima hyperplasia occurred over wires and connecting tubes, but it did not interrupt the patency of the arterial lumen. Discussion: An IA-NVD was created and tested to demonstrate its functionality and biocompatibility in the present experiments. The device may be safely applied to intracranial arteries, providing us a chance to test the efficacy of an upgrade version of the device on changing the course of an artery that compresses a cranial nerve. Abbreviations: CN = cranial nerve; EVT = endovascular treatment; H&E = hematoxylin and eosin; HFS = hemifacial spasm; IA-NVD = intra-arterial neurovascular decompressor; MVD = microvascular decompression; NVCS = neurovascular compression syndrome; REZ = root entry zone; SEM = scanning electron microscopy; TN = trigeminal neuralgia.

Contemporary concepts of pain surgery

Pain surgery is one of the historic foundations of neurological surgery. The authors present a review of contemporary concepts in surgical pain management, with reference to past successes and failures, what has been learned as a subspecialty over the past 50 years, as well as a vision for current and future practice. This subspecialty confronts problems of cancer pain, nociceptive pain, and neuropathic pain. For noncancer pain, ablative procedures such as dorsal root entry zone lesions and rhizolysis for trigeminal neuralgia (TN) should continue to be practiced. Other procedures, such as medial thalamotomy, have not been proven effective and require continued study. Dorsal rhizotomy, dorsal root ganglionectomy, and neurotomy should probably be abandoned. For cancer pain, cordotomy is an important and underutilized method for pain control. Intrathecal opiate administration via an implantable system remains an important option for cancer pain management. While there are encouraging results in small case series, cingulotomy, hypophysectomy, and mesencephalotomy deserve further detailed analysis. Electrical neuromodulation is a rapidly changing discipline, and new methods such as high-frequency spinal cord stimulation (SCS), burst SCS, and dorsal root ganglion stimulation may or may not prove to be more effective than conventional SCS. Despite a history of failure, deep brain stimulation for pain may yet prove to be an effective therapy for specific pain conditions. Peripheral nerve stimulation for conditions such as occipital neuralgia and trigeminal neuropathic pain remains an option, although the quality of outcomes data is a challenge to these applications. Based on the evidence, motor cortex stimulation should be abandoned. TN is a mainstay of the surgical treatment of pain, particularly as new evidence and insights into TN emerge. Pain surgery will continue to build on this heritage, and restorative procedures will likely find a role in the armamentarium. The challenge for the future will be to acquire higher-level evidence to support the practice of surgical pain management.

Vascular Offenders in Trigeminal Neuralgia: A Unified Classification and Assessment of the Outcome of Microvascular Decompression

BACKGROUND

Vascular loop compression remains the most accepted theory for trigeminal neuralgia (TN). Apart from the normal adjoining vascular loops, certain unusual vascular loops incriminated in TN such as vertebrobasilar dolichoectasia and pure venous compressions do not truly fit into the traditional classification. Moreover, vascular diseases such as cavernoma and aneurysms causing TN are considered as secondary TNs. There is a lack of unified classification for TN with underlying vascular offenders, otherwise amenable to microvascular decompression.

METHODS

We classified vascular offenders in TN (n = 53) into the usual offenders such as superior cerebellar artery or anterior inferior cerebellar artery loop with (n = 4) or without (n = 34) superior petrosal vein loop (n = 38, group I). The unusual vascular offenders (n = 15, group II) comprised unusual arterial loops (n = 4, IIa), pure venous compressions (n = 8, IIb) and vascular diseases (n = 3, IIc). The clinical symptoms, pain severity scores, and surgical outcomes were compared.

RESULTS

A right-sided preference and male predominance typified the unusual group. The incidence of atypical pain and sensory impairment was higher in group II. Group II also showed a less favorable immediate pain outcome, particularly the patients in group IIb. Group IIb also showed a higher incidence of postoperative hemorrhagic complications. However, long-term outcomes did not differ significantly.

CONCLUSIONS

Unusual vascular offenders in TN do constitute a significant population. They differ from the usual group with respect to the type of pain, gender, and side of involvement and tend to have more complications with similar pain outcomes after microvascular decompression.

Microvascular Decompression for Classical Trigeminal Neuralgia Caused by Venous Compression: Novel Anatomic Classifications and Surgical Strategy

BACKGROUND

Microvascular decompression of the trigeminal nerve is the most effective treatment for trigeminal neuralgia. However, when encountering classical trigeminal neuralgia caused by venous compression, the procedure becomes much more difficult, and failure or recurrence because of incomplete decompression may become frequent. This study aimed to investigate the anatomic variation of the culprit veins and discuss the surgical strategy for different types.

METHODS

We performed a retrospective analysis of 64 consecutive cases in whom veins were considered as responsible vessels alone or combined with other adjacent arteries. The study classified culprit veins according to operative anatomy and designed personalized approaches and decompression management according to different forms of compressive veins. Curative effects were assessed by the Barrow Neurological Institute (BNI) pain intensity score and BNI facial numbness score.

RESULTS

The most commonly encountered veins were the superior petrosal venous complex (SPVC), which was artificially divided into 4 types according to both venous tributary distribution and empty point site. We synthetically considered these factors and selected an approach to expose the trigeminal root entry zone, including the suprafloccular transhorizontal fissure approach and infratentorial supracerebellar approach. The methods of decompression consist of interposing and transposing by using Teflon, and sometimes with the aid of medical adhesive. Nerve combing (NC) of the trigeminal root was conducted in situations of extremely difficult neurovascular compression, instead of sacrificing veins. Pain completely disappeared in 51 patients, and the excellent outcome rate was 79.7%. There were 13 patients with pain relief treated with reoperation. Postoperative complications included 10 cases of facial numbness, 1 case of intracranial infection, and 1 case of high-frequency hearing loss.

CONCLUSIONS

The accuracy recognition of anatomic variation of the SPVC is crucial for the management of classical trigeminal neuralgia caused by venous compression. Selecting an appropriate approach and using reasonable decompression methods can bring complete postoperative pain relief for most cases. NC can be an alternative choice for extremely difficult cases, but it could lead to facial numbness more frequently.

Trigeminal Neuralgia

Trigeminal neuralgia (TN) is a sudden, severe, brief, stabbing, and recurrent pain within one or more branches of the trigeminal nerve. Type 1 as intermittent and Type 2 as constant pain represent distinct clinical, pathological, and prognostic entities. Although multiple mechanism involving peripheral pathologies at root (compression or traction), and dysfunctions of brain stem, basal ganglion, and cortical pain modulatory mechanisms could have role, neurovascular conflict is the most accepted theory. Diagnosis is essentially clinically; magnetic resonance imaging is useful to rule out secondary causes, detect pathological changes in affected root and neurovascular compression (NVC). Carbamazepine is the drug of choice; oxcarbazepine, baclofen, lamotrigine, phenytoin, and topiramate are also useful. Multidrug regimens and multidisciplinary approaches are useful in selected patients. Microvascular decompression is surgical treatment of choice in TN resistant to medical management. Patients with significant medical comorbidities, without NVC and multiple sclerosis are generally recommended to undergo gamma knife radiosurgery, percutaneous balloon compression, glycerol rhizotomy, and radiofrequency thermocoagulation procedures. Partial sensory root sectioning is indicated in negative vessel explorations during surgery and large intraneural vein. Endoscopic technique can be used alone for vascular decompression or as an adjuvant to microscope. It allows better visualization of vascular conflict and entire root from pons to ganglion including ventral aspect. The effectiveness and completeness of decompression can be assessed and new vascular conflicts that may be missed by microscope can be identified. It requires less brain retraction.

Microstructural alterations in trigeminal neuralgia determined by diffusion tensor imaging are independent of symptom duration, severity, and type of neurovascular conflict

OBJECT

In this prospective study diffusion tensor imaging (DTI) was used to evaluate the influence of clinical and anatomical parameters on structural alterations within the fifth cranial nerve in patients with trigeminal neuralgia (TN) due to neurovascular compression.

METHODS

Overall, 81 patients (40 men and 41 women; mean age 60 ± 5 years) with typical TN were included who underwent microsurgical decompression. Preoperative 3.0-T high-resolution MRI and DTI were analyzed in a blinded fashion. The respective fractional anisotropy (FA) and apparent diffusion coefficient values were compared with the clinical, imaging, and intraoperative data. This study was approved by the institutional review board, and written informed consent was obtained from all patients.

RESULTS

DTI analyses revealed significantly lower FA values within the vulnerable zone of the affected trigeminal nerve compared with the contralateral side (p = 0.05). The DTI analyses also included 3 patients without clear evidence of neurovascular conflict on preoperative MRI. No differences were seen between arterial and venous compression. Lower FA values were found 5 months after symptom onset; however, no correlation was found with the duration of symptoms or severity of compression.

CONCLUSIONS

DTI analysis allows the quantification of structural alterations, even in those patients without any discernible neurovascular contact on MRI. Moreover, our findings support the hypothesis that both the arteries and veins can cause structural alterations that lead to TN. These aspects can be useful for making treatment decisions.

Neurovascular study of the trigeminal nerve at 3 t MRI

This study aimed to show a novel visualization method to investigate neurovascular compression of the trigeminal nerve (TN) using a volume-rendering fusion imaging technique of 3D fast imaging employing steady-state acquisition (3D FIESTA) and coregistered 3D time of flight MR angiography (3D TOF MRA) sequences, which we called "neurovascular study of the trigeminal nerve". We prospectively studied 30 patients with unilateral trigeminal neuralgia (TN) and 50 subjects without symptoms of TN (control group), on a 3 Tesla scanner. All patients were assessed using 3D FIESTA and 3D TOF MRA sequences centered on the pons, as well as a standard brain protocol including axial T1, T2, FLAIR and GRE sequences to exclude other pathologies that could cause TN. Post-contrast T1-weighted sequences were also performed. All cases showing arterial imprinting on the trigeminal nerve (n = 11) were identified on the ipsilateral side of the pain. No significant relationship was found between the presence of an artery in contact with the trigeminal nerve and TN. Eight cases were found showing arterial contact on the ipsilateral side of the pain and five cases of arterial contact on the contralateral side. The fusion imaging technique of 3D FIESTA and 3D TOF MRA sequences, combining the high anatomical detail provided by the 3D FIESTA sequence with the 3D TOF MRA sequence and its capacity to depict arterial structures, results in a tool that enables quick and efficient visualization and assessment of the relationship between the trigeminal nerve and the neighboring vascular structures.

Microvascular decompression for trigeminal neuralgia

The microvascular decompression procedure has proven to be a safe and effective option in the surgical management of neurovascular compression syndromes in general and trigeminal neuralgia in particular. This article aims to serve as an overview of the decision-making process, application of the surgical technique, and clinical outcome pertaining to this procedure.