Trigeminal neuralgia caused by a transfixed arterial loop: illustrative case

Awake microvascular decompression with fat-teflon sandwich technique: Clinical implications of a novel approach for cranial nerve neuralgias

The neurovascular relationships in the trigeminal root entry zone were studied in 130 trigeminal root entry zones of 65 cadavers. No history of facial or trigeminal pain had been obtained during life in these subjects. The technique of intravascular injection, which allowed good visualization and evaluation of the neurovascular relationships, is described. A total of 42 examples of contact with the root entry zone and 10 examples of compression were identified. In 30 of the examples of contact, the finding could be related to an artery; in the other examples, it appeared to be due to veins. Of the arterial compressions, the superior cerebellar artery was responsible in 53.8%, the anterior inferior cerebellar artery was responsible in 25.6%, and pontine branches of the basilar artery were responsible for the remaining 20.6%. Only one instance of unequivocal compression by a vein was found. Other anatomical observations of interest are reported. The absence of a history of trigeminal neuralgia in the 7% of examined nerves in which root entry zone showed arterial compression is in marked contrast to the finding of 80% or more in the operative series for trigeminal neuralgia. It seems that vascular compressions may be the predominant but not the sole cause of trigeminal neuralgia.

Microvascular decompression (MVD) is the standard surgical treatment for classical trigeminal neuralgia (TN) with evident neurovascular compression. Internal neurolysis (IN) offers an alternative microsurgical technique. However, the physiological basis of symptom relief remains unclear. This study analyzed surgical outcomes and intraoperative conduction changes in patients without apparent vascular compression. Among 158 patients who underwent MVD for TN between February 2022 and March 2025, 14 had no definite vascular compression on preoperative 3D Magnetic resonance cisternography/angiogram-fusion imaging or intraoperative inspection and underwent IN. Conduction changes were classified into four patterns: (1) shortened latency with increased amplitude, (2) unchanged latency with increased amplitude, (3) unchanged latency and amplitude, and (4) recovery from unmeasurable to measurable conduction. The mean age was 64.9 years with an equal sex distribution. The right and left trigeminal nerves were affected in 10 and 4 patients, respectively. Nine patients had typical TN, and five had atypical features. Five patients had recurrent pain after previous MVD. Excellent outcomes (Barrow Neurological Institute [BNI] I-II) were achieved in 11 of 14 patients (78.6%), while 3 patients (21.4%) had partial pain relief (BNI III). Typical TN patients more frequently demonstrated conduction patterns 1 or 4, whereas atypical TN patients more often exhibited patterns 2 or 3. IN was associated with favorable clinical outcomes and intraoperative electrophysiological improvement in patients with TN without apparent vascular compression. These findings provide physiological observations accompanying clinical improvement following IN.

Trigeminal neuralgia is a chronic pain disorder affecting the face. In approximately 80% of cases, it is most commonly caused, when the root entry zone (REZ) of the trigeminal nerve is compressed by the superior cerebellar artery (SCA). The etiology of the remaining 20% of cases is distributed among venous, arteriovenous malformations, posterior fossa tumors, multiple sclerosis plaque compressions, and other pathologies. Combinations of those compressive factors are very rare.1234Herein, we present a video clip of microvascular decompression (MVD) in a 73-year-old female, who has failed conservative treatment with 6 medications over 10 years. She was affected by a unique triple compression of the right REZ by the SCA, anterior inferior cerebellar artery (AICA), and petrosal vein complex (Fig. 1A). Right-sided microsurgical decompression of the REZ of the trigeminal nerve through standard retrosigmoid craniotomy was performed by the senior author (K.I.A.). The SCA and AICA were separated from the nerve using Teflon pledgets. The petrosal vein complex was coagulated and divided, freeing up the right trigeminal nerve (Fig. 1B). The patient was discharged home on the third postoperative day with complete resolution of trigeminal neuralgia.The link to the Video can be found at:https://youtu.be/PYVvImGW0yE.

To the editor, I read with interest the article, “Differences in individual susceptibility affect the development of trigeminal neuralgia” by Duransoy et al. (2013). The authors have analyzed the possible pathogenesis of trigeminal neuralgia, with illustrative case examples. They have drawn very important conclusions, which may have implications in management of trigeminal neuralgia. The concept of microvascular compression at the root entry zone of trigeminal neuralgia as the pathogenetic mechanism of trigeminal neuralgia has been contested by various authors (Adams, 1989). This has been shown by the very high incidence of vascular compression at the root entry zone in asymptomatic population (Ramesh and Premkumar, 2009). Though the microvascular compression has been demonstrated in the majority of patients with trigeminal neuralgia and the microvascular decompression surgery results in pain relief, this alone does not explain the pathogenetic mechanism of trigeminal neuralgia. Focal demyelination has been observed in the area of vascular contact by some authors (Love and Coakham, 2001). But the demyelination does not occur in all individuals with the vascular contact. Hence, I also would agree with the authors’ view that there must be some individual susceptibility which predisposes to the development of focal demyelination at the root entry zone by vascular contact and causes trigeminal neuralgia and that mere vascular contact at the root entry zone need not result in trigeminal neuralgia. More studies and research are needed in this regard.

An anatomical study of the neurovascular relationships at the trigeminal root entry zone

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

Pain relief following microvascular decompression (MVD) for trigeminal neuralgia (TN) may be related to pain type, degree of neurovascular conflict, arterial compression, and location of compression. The objective of this study was to construct a predictive pain-free scoring system based on clinical and radiographic factors that can be used to preoperatively prognosticate long-term outcomes for TN patients following surgical intervention (MVD or internal neurolysis [IN]). It was hypothesized that contributing factors would include pain type, presence of an artery or vein, neurovascular conflict severity, and compression location (root entry zone). At the authors' institution 275 patients with type 1 or type 2 TN (TN1 or TN2) underwent MVD or IN following preoperative high-resolution brain MRI studies. Outcome data were obtained retrospectively by chart review and/or phone follow-up. Characteristics of neurovascular conflict were obtained from preoperative MRI studies. Factors that resulted in a probability value of < 0.05 on univariate logistic regression analyses were entered into a multivariate Cox regression analysis in a backward stepwise fashion. For the multivariate analysis, significance at the 0.15 level was used. A prognostic system was then devised with 4 possible scores (0, 1, 2, or 3) and pain-free survival analyses conducted. Univariate predictors of pain-free survival were pain type (p = 0.013), presence of any vessel (p = 0.042), and neurovascular compression severity (p = 0.038). Scores of 0, 1, 2, and 3 were found to be significantly different in regard to pain-free survival (log rank, p = 0.005). At 5 and 10 years there were 36%, 43%, 61%, and 69%, and 36%, 43%, 56%, and 67% pain-free survival rates in groups 0, 1, 2, and 3, respectively. While TN2 patients had worse outcomes regardless of score, a subgroup analysis of TN1 patients with higher neurovascular conflict (score of 3) had significantly better outcomes than TN1 patients without severe neurovascular conflict (score of 1) (log rank, p = 0.005). Regardless of pain type, those patients with severe neurovascular conflict were more likely to have arterial compression (99%) compared to those with low neurovascular conflict (p < 0.001). Pain-free survival was predicted by a scoring system based on preoperative clinical and radiographic findings. Higher scores predicted significantly better pain relief than lower scores. TN1 patients with severe neurovascular conflict had the best long-term pain-free outcome.

To evaluate the correlation of trigeminal radiculopathy with anatomical relationships of trigeminal nerve root, brainstem, tumors and vessels in patients with vestibular schwannomas. A retrospective analysis included 153 patients (106 females and 47 males aged 22-82 years) with vestibular schwannomas who underwent surgery via retromastoid approach. Preoperative trigeminal radiculopathy (facial pain and sensory disturbances) was examined after microsurgical resection. Brainstem compression was analyzed by comparison of transverse size of contralateral to vestibular schwannoma half of brainstem and ipsilateral side. Tumor-induced brainstem and trigeminal nerve compression was found in 115 cases. Sixty-four of these patients had trigeminal radiculopathy symptoms. Degree of brainstem compression was significantly higher in trigeminal radiculopathy group. Facial hypoesthesia was found in 61patients, trigeminal neuralgia - in 5 cases, neuropathic pain - in 3 patients. Thirty-seven patients without brainstem compression had no trigeminal nerve involvement. One patient had trigeminal neuralgia following compression by superior cerebellar artery. Total resection with brainstem and trigeminal nerve decompression were performed in all cases. Isolated or combined compression of trigeminal nerve root was noted in 9 patients with trigeminal neuralgia and neuropathic pain, in 2 with facial numbness and in 2 patients without trigeminal symptoms. In case of trigeminal neuralgia following compression by superior cerebellar artery, vascular decompression was performed only in patients with facial pain and numbness. Facial pain completely resolved in all patients. Complete or partial sensory restoration was noted in 25 cases. No facial sensory disorders were noted in 26 cases, transient sensory deterioration - in 10 patients. Trigeminal radiculopathy is caused by severe brainstem compression following vestibular schwannomas and usually results sensory disturbances and rarely facial pain. The impact of tumor on trigeminal nerve root and brainstem trigeminal pathways can be accompanied by vascular compression by superior cerebellar artery. Regression of trigeminal radiculopathy symptoms after resection of vestibular schwannoma is caused by decompression of trigeminal nerve root and brainstem. In case of concomitant neurovascular syndrome, vascular decompression is indicated.

Objective To analyze the role of high-resolution magnetic resonance tomographic angiography(MRTA)in microvascular decompression(MVD)and etiological study of trigeminal neuralgia(TN). Methods Craniocerebral MRI was performed in 84 cases with TN and three-dimensional time-of-flight(3D-TOF)MR angiography(MRA)using spoiled gradient-recalled-echo sequences was applied to observe the course of the trigeminal nerve and its relation to adjacent blood vessels. Among these cases, 68 underwent surgical treatment. MRI findings and intraoperative manifestations were analyzed comparatively and the correlation between TN and local vascular compression was also observed. Results MRI showed that the affected side blood vessels of 79 cases touched the trigeminal nerve and the intact side vessels of 12 cases touched the trigeminal nerve.Among the 68 cases undergoing MVD,62 had surgical results entirely consistent with MRI findings,4 had their relatively fine arteries oppressing the trigeminal nerve and 2 had petrosal vein compression combined with arachnoid adhesion. Conclusion Vascular compression at the root entry zone(REZ) of the trigeminal nerve is the one of the primary causes of TN.The technique of 3D-TOF MRA may determine the correlation between blood vessels and nerves in patients with TN,which is helpful for the diagnosis of etiological factors for TN and benefits MVD. Key words: Trigeminal neuralgia; Magnetic resonance angiography; Microvasculardecompression; Etiology

Classical trigeminal neuralgia (TN) is a severe neuropathic facial pain disorder commonly associated with neurovascular compression at the trigeminal nerve root entry zone (REZ). Neurosurgical interventions can relieve TN pain, but the mechanisms underlying these effects are unknown. We determined whether the abnormalities we previously reported at the REZ of TN patients using diffusion tensor imaging (DTI) and brain gray matter (GM) analyses resolve after effective neurosurgical treatment. Twenty-five patients who underwent either microvascular decompression surgery or Gamma Knife radiosurgery for right-sided TN had magnetic resonance imaging scans before and after treatment and were compared with age-matched controls. Cortical thickness and voxel-based morphometry examined specific brain GM we previously reported as abnormal in TN. White matter metrics of fractional anisotropy (FA), mean, radial, and axial diffusivities (MD, RD, and AD, respectively) were extracted bilaterally from each trigeminal REZ. Before treatment, patients had widespread GM abnormalities including thinner ventral anterior insula (vAI) cortex, and REZ microstructural abnormalities (lower FA, and higher MD, RD, and AD) compared with controls. We considered a 75% reduction in pain as effective treatment. The right vAI was the only GM region that normalized toward the level of healthy controls after effective treatment. At the REZ, effective treatment reversed FA, MD, RD, and AD abnormalities and was correlated with pain relief after treatment. These results demonstrate that treatment can effectively resolve pain by normalizing REZ abnormalities, which may influence vAI abnormalities. Future studies should consider DTI as an adjunct to assess the patient outcome and subtle microstructural changes after treatment.

Objective: To assess the long-term results of microvascular decompression (MVD) using autologous muscle for trigeminal neuralgia (TGN). Methods: We retrospectively reviewed all primary MVD patients for typical classic TGN without previous surgery between 2000 and 2019 at a tertiary supraregional neurosurgery centre. Age, sex, surgical findings, surgical outcomes, complications, and recurrence at 1 year, 5 years, and final follow-up were recorded. Pain relief was measured with the Barrow Neurological Institute (BNI) score. Categorical variables were compared using the Chi-squared test with continuity correction, and Kaplan-Meier curves and Cox regression were used to determine recurrence risk factors. Results: We analyzed 1035 patients with a median follow-up of 8 years (IQR 5-13 years; range 3-20 years). Immediately after surgery, 893 patients (86.7%) had complete pain relief, 110 (10.3%) had partial pain relief (both groups did not need medication), and 32 (2.9%) had no relief. There were 141 recurrences (13.8%) at a median of 3 years (IQR 2-6 years) after surgery. The proportion of patients without recurrence at 1 year was 97%, 90% at 5 years, 85% at 10 years, 83% at 15 years, and 81% at 20 years. There was no difference in the likelihood of recurrence between patients with complete (114/907 12.6% recurrences) or partial (19/110 17.9% recurrences) pain relief (log-rank p=0.124). The rate of MVD failure was significantly higher in patients with venous compression (N=322, N=16, 5%) than arterial compression (N=14/703, 2%) (chi-squared p=0.015). In a Cox Proportional Hazards model, the hazards of recurrence for venous compression and no immediate postoperative pain relief were 1.62 (95% confidence interval (CI) 1.16-2.27) and 2.65 (95% CI 1.45-4.82), respectively. 124 (12.1%) complications were documented: 44 facial numbness (35.9%), facial nerve palsy (N=37, 29.8%), CSF leak (N=13, 10.5%), and diplopia (N=5, 4%) which resolved in all patients. Conclusions: MVD with autologous muscle provides long-lasting pain relief in TGN with vascular compression with minimum morbidity and is a viable alternative to synthetic materials.

This is the case of an 86-yr-old gentleman who presented with left facial pain exacerbated by eating, drinking, chewing, and shaving (distribution: V2, V3). The patient was diagnosed with trigeminal neuralgia and was refractory to medications. Imaging showed a superior cerebellar artery (SCA) loop adjacent to the trigeminal nerve root entry zone and a decision to perform a microvascular decompression of the fifth nerve was presented to the patient. After patient informed consent was obtained, a standard 3 cm × 3 cm retrosigmoid craniotomy was performed with the patient in a supine head turned position and in reverse Trendelenburg. The arachnoid bands tethering the SCA to the trigeminal nerve were sharply divided. A slit was then made in the tentorium and a 3 mm fenestrated clip was then used to secure the transposed SCA away from the trigeminal nerve. The SCA proximal to this was slightly patulous in its course so a small amount of a fibrin glue was also used to secure the more proximal SCA to the tentorium. The patient was symptom-free postoperatively and no longer required medical therapy. Additionally, imaging was consistent with adequate separation of the nerve from adjacent vessels.1-5.

New insights into the trigeminal nerve somatotopy: Lessons from partial sensory rhizotomy

Due to its anatomical features, the vertebrobasilar artery complex (VBA) seldom contributes to the neurovascular conflict in patient with trigeminal neuralgia (TN). However, once it offends the trigeminal root, this large artery is really difficult to manipulate during microvascular decompression (MVD) surgery. Therefore, the surgical strategy for such cases needs to be detailed in order to obtain a satisfactory outcome. From 2009 through 2011, 475 consecutive TN patients underwent MVDs in our department. Among them, ten were found in which an ipsilateral deviating ectatic vertebrobasilar artery complex (VBA) offended the trigeminal nerve. Those cases were focused on in this study and each operation was analyzed retrospectively. During the operation, the vertebral artery was regarded as the direct culprit in six (60 %) patients, while the basilar artery in four (40 %). As companions, some smaller vessels were also observed to be close to the nerve, including the superior cerebellar artery (SCA) in five, veins in two and anterior inferior cerebellar artery (AICA) in two. The neurovascular conflict was discovered in the cisternal segment of the trigeminal root in eight, while in the root entry zone (REZ) in two. In six out of the ten cases, the affected nerves were demonstrated to be squeezed towards the tentorium by the ectatic VBA. Postoperatively, the symptom of pain totally disappeared immediately in eight (80 %) patients, while it was relieved apparently in two (20 %). During the follow-up period of 3-30 months, no recurrence or complication was found, except for one patient who had numbness of the face. With a proper strategy, MVD is probably the most effective therapy for the TN cases caused by ectatic vertebrobasilar artery complex. The substance of the surgery is to withdraw the proximal vertebral artery caudally via a lateroinferior cerebellar approach.