Trigeminal Root Research Articles

Erratum for the Research Resource: "Harmonized cross-species cell atlases of trigeminal and dorsal root ganglia" by S. Bhuiyan et al.

Erratum for the Research Resource: "Harmonized cross-species cell atlases of trigeminal and dorsal root ganglia" by S. Bhuiyan et al.

An Application of Combined Transpetrosal Approach with Micro-neurovascular Transposition in Recurrent Trigeminal Neuralgia caused by Dolichoectatic Vertebral Artery

PurposeIn general, the superior cerebellar artery (SCA) is the most prevalent vessel that compresses the trigeminal nerve root exit zone (TGNREZ) and is responsible for trigeminal neuralgia (TGN). Nevertheless, the surgical outcome is less efficacious when the offending vessel is a dolichoectatic vertebrobasilar vessel (DVB). In addition, the potential for post-procedural adhesion and fibrosis renders recurrent TGN after prior surgery an extremely challenging operation. MethodsWe describe our surgical strategy and procedure that effectively resolved recurrent TGN in a patient whose offending vessel was a large DVB following standard microvascular decompression surgery. The size and nature of the offending DVB indicated that there was limited space for mobilization away from the TGNREZ, as evidenced by previous operative findings. Consequently, the patient's TGN may not be effectively treated by re-operating with the same standard lateral suboccipital approach. ResultsOur surgical approach comprised the creation of an expanded area to facilitate the mobilization of the DVB from the TGNREZ, as well as the untethering of the trigeminal nerve and its subsequent mobilization from the DVB using the transposition technique. ConclusionA combined transpetrosal approach with micro-neurovascular transposition technique was selected to achieve all objectives. A case illustration with a surgical video is demonstrated.

A new management strategy for Hemimasticatory spasm.

Hemimasticatory spasm (HMS) is an uncommon movement disorder of the trigeminal motor rootlet characterized by unilateral, involuntary, and paroxysmal contractions of the muscles of mastication. The mechanisms for HMS are still unclear, and an efficient treatment strategy still needs to be developed. This study aims to investigate the clinical features and surgical treatment of HMS. 12 patients with HMS were included in our study. The patient data regarding clinical characteristics, neuroimaging presentations, intraoperative findings and treatment outcomes were analyzed retrospectively. Highly selective trigeminal motor root rhizotomy (HSTR) combined with microvascular compression was performed in 9 cases with neurovascular conflict, while 3 patients without vascular compression underwent HSTR only. Intraoperative findings showed that there is one patient with 6 branches of the trigeminal motor roots, 3 patients with 2 trigeminal motor roots, and the remaining patients have 3-4 trigeminal motor roots. Seven patients had 2 motor branches severed, 3 patients had 1 motor branch severed, and 2 patients each had 3 motor branches severed. 9 patients recovered uneventfully and showed no signs of spasms, and the remaining 2 patients experienced complete disappearance of symptoms within 3 months after surgery. One patient relived immediately postoperatively but recurred 2 years later. The surgical procedures of HSTR can significantly alleviate the clinical symptoms of patients with masseter spasms without bringing serious complications to patients.

A unique presentation of trigeminal neuralgia related to a central nervous tissue choristoma along the trigeminal nerve root: illustrative case.

Trigeminal neuralgia (TNa), or tic douloureux, is characterized by severe facial pain triggered by everyday activities. Recurring and intense TNa pain results from localized demyelination within the affected nerve segment. The primary cause of TNa is typically vascular compression, with the superior cerebellar artery being the most common vessel. Tumors, multiple sclerosis, and infectious diseases such as herpes are less frequent causes of TNa. The authors present a unique case in which TNa was caused by an aberrant mass resembling a schwannoma during surgery. However, histological examination revealed heterotopic benign central nervous neurons and myelinated axons, which could represent a choristoma in the cisternal segment of the portio major of the trigeminal nerve. Following surgery, the patient's TNa was completely resolved. To the best of the authors' knowledge, this is the first documented case of a central nervous tissue choristoma causing TNa and responding positively to surgical intervention, aside from one previous report that did not specifically use the term "choristoma" in identifying the lesion. This case highlights the challenges involved in diagnosing and managing a rare TNa presentation, with a particular focus on pathology findings. It underscores the potential role of surgery for patients whose condition is resistant to medical intervention. https://thejns.org/doi/10.3171/CASE24384.

Technical report on intra-operative trigeminal root mapping in percutaneous lesioning for trigeminal neuralgias

PurposePercutaneous lesioning-techniques for treating refractory Trigeminal Neuralgias not amenable to Micro-Vascular Decompression remain useful in neurosurgical practice. Success, avoidance of complications and reduction of side-effects depend on the accurate location of the lesion-maker especially for Radio-Frequency-Thermo-Rhizotomy (RF-Th-Rh).Added to X-ray-guidance, Intra-Operative Neurophysiology can be of significant help to achieve optimal accuracy of the surgery.Based on previous research, this article aims to describe the simplest way to use direct electrical stimulation of the trigeminal root to evoke clinically observable muscle responses allowing to precisely position the tip of the needle for accurate lesioning.Technique to evoke specific localizing muscle responsesMasticatory twitches can be easily produced by stimulating the motor root, through orthodromic conduction to the masticatory muscles.Evoked Muscle Responses (EMRs) can be elicited in the facial nerve territory by stimulating the sensory rootlets, through Trigemino-Facial Reflexes’ pathways (TFRs). Responses in the Orbicularis Oculi is the well-known and readily used “Blink reflex”. On the contrary, TFRs in the lower territory of the facial nerve escaped clinical investigations not having been explored under direct stimulation of the trigeminal root. For both, stimulation at 5 c/s produces better observable twitches (because saccadic) than at 50 c/s which elicits tetanic contractions.ConclusionThe localizing-value of these facial EMRs (associated to evocation of paresthesias) and of the masticatory responses, justifies mapping the trigeminal root before lesioning. Their use could be extended to the other lesioning-techniques: not only Glycerol Neurolysis but also to Balloon Compression (to ascertain location of the trocar at the contact of the TGN inside the Meckel cave) and Open partial Rhizotomies (before deciding to cut the rootlets corresponding to the trigger-zone). This is of importance since lesioning-techniques are needed because not all trigeminal neuralgias are responsive to or even indications of Micro-Vascular Decompression.

A pontine-specific axonal niche supports de novo gliomagenesis.

The trigeminal root entry zone underlies pontine-specific gliomagenesis driven by H3.1K27M and its co-occurring mutations.

MRI trigeminal nerve digitalization for trigeminal neuralgia diagnosis

ObjectiveThis study aimed to determine the affected side in trigeminal neuralgia by examining the digitized angle ratio value between the bilateral trigeminal nerve root axis and the pontine tangent line. MethodsTrigeminal nerve-related MRI from 81 patients with trigeminal neuralgia (TNG) and 20 healthy persons were divided into normal and diseased groups. All the patient's films were scanned to form the images stored in compute. The following skull base MRI parameters were measured by Image J software: 1. bilateral trigeminal nerve root-pontine tangent line angle (T-P angle) values were measured. 2. Clinical symptoms were used to record the affected side of diseased patients, and 3. Nerve vascular confliction (NVC) and the side with NVC were subdivided (none/left/right/both sides). The normal T-test proved that P Value between the normal group and the diseased group. The T-P angle Ratio of the normal group was utilized to estimate the normal patient Ratio to establish the 95% confidence interval (CI). In diseased group, if the ratio was ≥ the reference value, the afflicted side was determined by comparing the max T-P angle with the actual affected side for accuracy. A binomial distribution test verified its statistical significance. ResultsThe T-P angle was significantly different between patients with TNG and normal subjects (p < 0.001). The T-P angle ratio (R) ≥ 1.238 was used to diagnose the affected side, achieving an overall accuracy rate of 82% (95% CI: 75%–89%). For patients without NVC, the accuracy was 78% (95% CI: 60%–95%), while for those with unilateral NVC, it was 91% (95% CI: 82%–100%), and for those with bilateral NVC, it was 69% (95% CI: 52%–86%). For 1 ≤ R < 1.238, the accuracy for diagnosing the affected side using NVC was 80% (95% CI: 67%–93%). ConclusionThe T-P angle is significantly higher in TNG patients than in normal patients (p < 0.001)., making it a valuable diagnostic tool. This measurement aids in guiding microvascular decompression surgery, particularly in non-vascular compression cases, and enhances postoperative evaluation. Future integration into standard protocols could improve surgical outcomes and patient care.

Trigeminal Neuralgia and Associated Hydrocephalus: Not a Mere Incidental Finding? A Case Report and Literature Review

BACKGROUND: Trigeminal neuralgia (TN) is most commonly related to vascular compression of the trigeminal root entry zone into the brainstem. Secondary causes of compression are much less common. TN as a sole manifestation of hydrocephalus has rarely been reported in the literature. CASE REPORT: We describe a young woman with medically resistant TN, who was discovered to have a tectal plate glioma causing secondary obstructive hydrocephalus. In addition, she had an incidental finding of ecchordosis physaliphora. Cerebrospinal fluid diversion by an endoscopic third ventriculostomy resulted in TN resolution. CONCLUSION: Hydrocephalus is a rare diagnosis to consider as a secondary cause for TN. Since the literature on this is sparse, it can be only suggested that in very select cases, treating the hydrocephalus may also treat the TN. Additional studies and reports are required. KEY WORDS: Trigeminal neuralgia, hydrocephalus, ecchordosis physaliphora, tectal plate glioma

Trigeminal neuralgia.

Trigeminal neuralgia (TN) is a facial pain disorder characterized by intense and paroxysmal pain that profoundly affects quality of life and presents complex challenges in diagnosis and treatment. TN can be categorized as classical, secondary and idiopathic. Epidemiological studies show variable incidence rates and an increased prevalence in women and in the elderly, with familial cases suggesting genetic factors. The pathophysiology of TN is multifactorial and involves genetic predisposition, anatomical changes, and neurophysiological factors, leading to hyperexcitable neuronal states, central sensitization and widespread neural plasticity changes. Neurovascular compression of the trigeminal root, which undergoes major morphological changes, and focal demyelination of primary trigeminal afferents are key aetiological factors in TN. Structural and functional brain imaging studies in patients with TN demonstrated abnormalities in brain regions responsible for pain modulation and emotional processing of pain. Treatment of TN involves a multifaceted approach that considers patient-specific factors, including the type of TN, with initial pharmacotherapy followed by surgical options if necessary. First-line pharmacological treatments include carbamazepine and oxcarbazepine. Surgical interventions, including microvascular decompression and percutaneous neuroablative procedures, can be considered at an early stage if pharmacotherapy is not sufficient for pain control or has intolerable adverse effects or contraindications.

Effect of pseudoprogression of vestibular schwannomas on dynamics of trigeminal and facial nerves dysfunction after stereotactic radiosurgery

The use of stereotactic radiosurgery (SRS) in the treatment of vestibular schwannomas (VS) is due to a high level of local control of tumor growth, a lower level of functional impairment, a relatively low cost of treatment compared to microsurgery, and the preservation of a high quality of life [1–7]. The development of post-radiation pseudoprogression of the VS can lead to increased compression of adjacent brain structures, including the trigeminal and facial nerves with the appearance of their irritation or lack of function. The purpose of the study: to investigate the effect of post-radiation pseudoprogression on the function of cranial nerves 5 and 7 after SRS. Material and methods. The analysis included 128 patients with 3 or more control MRIs and a follow-up period of 12 months and over, who had at least 3 control examinations by a neurologist and otoneurologist. The median clinical follow-up was 52 months. The analyzed patients (n=128) were divided into 2 main groups: group 1 (n=99) — without previous microsurgery (MS), group 2 (n=29) — previously operated patients. Results. Irritation of nerves 5 and 7 is observed after SRS for VS exclusively against the background of pseudoprogression. Persistent de novo facial nerve failure after SRS is a rare complication (0.9 %). Symptoms of dysfunction of the 5th and 7th nerves predominate in the group of large VS (stages C and D according to Hasegawa) (p&lt;0.0001). The prolonged course of pseudoprogression determines a tendency to longer dysfunction of the cranial nerves, but does not affect the final result. Conclusion. Irritation of the 5th and 7th nerves, relieved by anticonvulsants, is not an indication for surgical removal of the tumor or re-irradiation, as it goes away on its own due to subsequent natural shrinkage of the tumor. However, the pharmacoresistant course of trigeminal neuralgia may be due to compression of the trigeminal nerve root between the tumor and petrous apex, and therefore subtotal tumor removal may be justified for root decompression.

Microvascular Decompression Plus Partial Resection of Trigeminal Nerve Motor Root for Hemimasticatory Spasm Combined With Hemifacial Atrophy: A Good Choice or Not?

Hemimasticatory spasm (HMS) combined with hemifacial atrophy is a rare clinical entity with an unclear etiology. The authors report a 58-year-old female suffering from HMS and hemifacial atrophy, which performed microvascular decompression plus partial resection of the trigeminal nerve motor root, which is the first report in worldwide. The vascular compression of the trigeminal nerve motor root was found in surgery, the authors completed the aforementioned surgical method. The symptoms of HMS disappeared after surgery but recurred after 8 months.

An Integrated Approach Through Panchakarma in the Management of Trigeminal Neuralgia W.S.R Anantavata

Anantavata is a Tridosha Pradhana vyadhi afflicting the Manya, Hanu, Shiras, Lalatadi Pradesha characterised by Teevra Ruja, Kampa in the affected parts, Hanu graha, Akshiroga. It can be correlated with trigeminal neuralgia, which is one of the most painful conditions known to the mankind and is most commonly caused due to compression of the root of trigeminal nerve. The pain is so severe that it affects the day-to-day activities of the patients eventually hampering the quality of life. In extreme conditions, it also leads to insomnia, psychological derangements and depression and makes the patient dependent on anti-depressants and analgesics for their lifetime. Hence an intervention, that focuses on the root cause, alleviates the pain, strengthens the affected part and prevents reoccurrence is quintessential. In the view of achieving the same, the following case study was taken up where a female patient aged 57 years, complained of numbness over whole face, shocking sensation over Rt. half of the face, hyperaesthesia and pain in neck radiating to B/L upper limbs since 4 years and was treated with Abhyanga, Parsisheka, Nasya, Shirodhara, Gandusha leading to a significant improvement in the signs and symptoms.

Endoscopic Retrolabyrinthine Craniotomy for Exposure of the Trigeminal Nerve Root Entry Zone: Volumetric Analysis of Anatomic Exposure in the Cadaver.

Exposure of the root entry zone (REZ) of the trigeminal nerve (TN) for microvascular decompression is commonly obtained with a retrosigmoid approach, with or without endoscopic assistance. We hypothesized that adequate exposure of the TN REZ could be obtained through an endoscopic retrolabyrinthine (RL) approach. We aim to quantify exposure of the REZ of the TN using endoscopic RL approach, with and without drilling of the suprameatal tubercle of the internal auditory canal. Surgical dissection was performed bilaterally on 3 embalmed cadaveric human heads at the anatomy laboratory of the House Institute. Heads were scanned for volumetric analysis using 3D Slicer software both before and after dissection. Extent of exposure was quantified in 2 ways: first, by assessment of the surgeon's ability to visualize 16 predetermined anatomic landmarks with the endoscope and second, we estimated the "working" area by placing fiducials under the fully endoscopic view and calculating the resultant 3D volume. Using the standard endoscopic RL approach, an average of 13.8 landmarks (range 12-16) was visualized. The estimated working volume exposed by the RL on each side of each head varied from 189.28 to 527.85 mm3. Drilling of the suprameatal tubercle provided both increases in landmark visualization and, on average, an additional 55 mm3 of working volume. The endoscopic RL approach is a viable alternative to the standard retrosigmoid approach. Potential advantages of the RL include a more lateral trajectory that minimizes the need for cerebellar retraction and a shorter working distance and shallower angle to the cerebellopontine angle. Potential disadvantages include longer surgery time, increased technical difficulty of exposure, and potential for cerebrospinal fluid leak and or hearing loss.

Transorbital approach to the cavernous sinus: an anatomical study of the related cranial nerves.

The cavernous sinus (CS) is a demanding surgical territory, given its deep location and the involvement of multiple neurovascular structures. Subjected to recurrent discussion on the optimal surgical access, the endoscopic transorbital approach has been recently proposed as a feasible route for selected lesions in the lateral CS. Still, for this technique to safely evolve and consolidate, a comprehensive anatomical description of involved cranial nerves, dural ligaments, and arterial relations is needed. Detailed anatomical description of the CS, the course of III, IV, VI, and V cranial nerves, and C3-C7 segments of the carotid artery, all described from the ventrolateral endoscopic transorbital perspective. Five embalmed human cadaveric heads (10 sides) were dissected. An endoscopic transorbital approach with lateral orbital rim removal, anterior clinoidectomy, and petrosectomy was performed. The course of the upper cranial nerves was followed from their apparent origin in the brainstem, through the middle fossa or cavernous sinus, and up to their entrance to the orbit. Neuronavigation was used to follow the course of the nerves and to measure their length of surgical exposure. The transorbital approach allowed us to visualize the lateral wall of the CS, with cranial nerves III, IV, V1-3, and VI. Anterior clinoidectomy and opening of the frontal dura and the oculomotor triangle revealed the complete course of the III nerve, an average of 37 (±2) mm in length. Opening the trigeminal pore and cutting the tentorium permitted to follow the IV nerve from its course around the cerebral peduncle up to the orbit, an average of 54 (±4) mm. Opening the infratrochlear triangle revealed the VI nerve intracavernously and under Gruber's ligament, and the extended petrosectomy allowed us to see its cisternal portion (27 ± 6 mm). The trigeminal root was completely visible and so were its three branches (46 ± 2, 34 ± 3, and 31 ± 1 mm, respectively). Comprehensive anatomic knowledge and extensive surgical expertise are required when addressing the CS. The transorbital corridor exposes most of the cisternal and the complete cavernous course of involved cranial nerves. This anatomical article helps understanding relations of neural, vascular, and dural structures involved in the CS approach, essential to culminating the learning process of transorbital surgery.

Progress in study on animal models of trigeminal neuralgia.

Trigeminal neuralgia is a manifestation of orofacial neuropathic pain disorder, always deemed to be an insurmountable peak in the field of pain research and treatment. The pain is recurrent, abrupt in onset and termination similar to an electric shock or described as shooting. A poor quality of life has been attributed to trigeminal neuralgia, as the paroxysms of pain may be triggered by innocuous stimuli on the face or inside the oral cavity, such as talking, washing face, chewing and brushing teeth in daily life. The pathogenesis of trigeminal neuralgia has not been fully elucidated, although the microvascular compression in the trigeminal root entry zone is generally considered to be involved in the emergence and progression of the pain disorder. In addition, orofacial neuropathic pain restricted to one or more divisions of the trigeminal nerve might be secondary to peripheral nerve injury. Based on current hypotheses regarding the potential causes, a variety of animal models have been designed to simulate the pathogenesis of trigeminal neuralgia, including models of compression applied to the trigeminal nerve root or trigeminal ganglion, chronic peripheral nerve injury, peripheral inflammatory pain and center-induced pain. However, it has not yet been possible to determine which model can be perfectly employed to explain the mechanisms. The selection of appropriate animal models is of great significance for the study of trigeminal neuralgia. Therefore, it is necessary to discuss the characteristics of the animal models in terms of animal strains, materials, operation methods and behavior observation, in order to gain insight into the research progress in animal models of trigeminal neuralgia. In the future, animal models that closely resemble the features of human trigeminal neuralgia pathogenesis need to be developed, with the aim of making valuable contributions to the relevant basic and translational medical research.

Image Diagnosis of Trigeminal Neuralgia

Classic trigeminal neuralgia is mainly caused by arterial compression; most cases involve the superior cerebellar artery, followed by the anterior cerebellar, basilar, and vertebral arteries. The detection of neurovascular conflicts in trigeminal neuralgia requires special magnetic resonance imaging(MRI)modalities, including high-resolution three-dimensional(3D)-T2 sequence, 3D-time of flight angiography, 3D-T1 sequencing with gadolinium injection, and merged images of these sequences. The conflicting sites are not necessarily restricted to the root entry zone of the trigeminal nerve root and can be located more distally, proximal to the Meckel's cavum. Arterial compression and its severity, including displacement, angulation, distortion, and atrophy of the trigeminal root, are good predictors of the long-term efficacy of decompression surgery. Veins, primarily the transverse pontine vein, comprise 10%-20% of all causative vessels in trigeminal neuralgia. Gadolinium-enhanced 3D-T1 MRI and high-resolution 3D-T2 MRI merged with computed tomographic angiography are useful for detecting venous compression.

A combined radiomics and anatomical features model enhances MRI-based recognition of symptomatic nerves in primary trigeminal neuralgia.

The diagnosis of primary trigeminal neuralgia (PTN) in radiology lacks the gold standard and largely depends on the identification of neurovascular compression (NVC) using magnetic resonance imaging (MRI) water imaging sequences. However, relying on this imaging sign alone often fails to accurately distinguish the symptomatic side of the nerve from asymptomatic nerves, and may even lead to incorrect diagnoses. Therefore, it is essential to develop a more effective diagnostic tool to aid radiologists in the diagnosis of TN. This study aims to establish a radiomics-based machine learning model integrating multi-region of interest (multiple-ROI) MRI and anatomical data, to improve the accuracy in differentiating symptomatic from asymptomatic nerves in PTN. A retrospective analysis of MRI data and clinical anatomical data was conducted on 140 patients with clinically confirmed PTN. Symptomatic nerves of TN patients were defined as the positive group, while asymptomatic nerves served as the negative group. The ipsilateral Meckel's cavity (MC) was included in both groups. Through dimensionality reduction analysis, four radiomics features were selected from the MC and 24 radiomics features were selected from the trigeminal cisternal segment. Thirteen anatomical features relevant to TN were identified from the literature, and analyzed using univariate logistic regression and multivariate logistic regression. Four features were confirmed as independent risk factors for TN. Logistic regression (LR) models were constructed for radiomics model and clinical anatomy, and a combined model was developed by integrating the radiomics score (Rad-Score) with the clinical anatomy model. The models' performance was evaluated using receiver operating characteristic curve (ROC) curves, calibration curves, and decision curve analysis (DCA). The four independent clinical anatomical factors identified were: degree of neurovascular compression, site of neurovascular compression site, thickness of the trigeminal nerve root, and trigeminal pons angle (TPA). The final combined model, incorporating radiomics and clinical anatomy, achieved an area under the curve (AUC) of 0.91/0.90 (95% CI: 0.87-0.95/0.81-0.96) and an accuracy of approximately 82% in recognizing symptomatic and normal nerves. The combined radiomics and anatomical model provides superior recognition efficiency for the symptomatic nerves in PTN, offering valuable support for radiologists in diagnosing TN.

Assessment of Trigeminal Nerve Root Demyelination in Patients with Primary Trigeminal Neuralgia Using Macromolecular Proton Fraction Imaging

Assessment of Trigeminal Nerve Root Demyelination in Patients with Primary Trigeminal Neuralgia Using Macromolecular Proton Fraction Imaging

Use of a 3D exoscope in microvascular decompression of the trigeminal nerve root.

For microvascular decompression surgery, adequate visualization of the trigeminal nerve root is essential. Several visualization techniques with operating microscopes, endoscopes, a combination of both, and exoscopes have been described. In this video, the authors use a 4K 3D exoscope (ORBEYE) as it offers superb optical image quality with a high degree of magnification and illumination in the cerebellopontine angle. Other advantages are surgeon ergonomics, a very good depth of field for the entire operating team, and potentially evolving visualization technologies like narrow-band imaging-essential points for microvascular decompression surgery where the aim is to create the best possible visibility in a narrow corridor. The video can be found here: https://stream.cadmore.media/r10.3171/2023.10.FOCVID23149.

Microvascular Decompression for Trigeminal Neuralgia Caused by Trigeminocerebellar Artery

The trigeminocerebellar artery(TCA)is a unique branch of the basilar artery. The TCA was first described in detail by Markovic et al. in 1996. The incidence of TCA was 6.9%-13.3% in previous cadaveric studies. The TCA branches from the distal part of the basilar artery, courses very close to the trigeminal nerve root entry zone, and occasionally twists or encircles the nerve root. A close relationship between the TCA and trigeminal nerve can cause trigeminal neuralgia(TN). This characteristic course of TCA requires adjuvant decompression techniques performed by the operators. In the microvascular decompression for TN caused by the TCA, operators should pay attention to the following: 1)sufficient arachnoid dissection around the TCA, 2)combined transposition and interposition technique, 3)decompression of perforators and vessels penetrating the nerve, and 4)recognition of the existence of the TCA.