Surgical treatment of trigeminal neuralgia with no neurovascular compression: A retrospective study and literature review

Treatment of recurrent trigeminal neuralgia after microvascular decompression: How to select

BACKGROUND

This study aimed to investigate individualized treatment strategies and clinical outcomes in patients with recurrent trigeminal neuralgia after undergoing microvascular decompression (MVD).

METHODS

One hundred forty-four patients with recurrent trigeminal neuralgia after MVD were retrospectively examined and grouped according to treatment. Surgical efficacy and pain recurrence were analyzed as outcomes.

RESULTS

Repeat craniotomy was performed in 31 patients (21.5 %), percutaneous balloon compression (PBC) in 67 (46.5 %), and radiofrequency thermocoagulation (RFT) in 46 (32.0 %). Effectiveness did not differ among the three types of treatment (P = 0.052). The incidence of postoperative complications, including trigeminal nerve cardiac reflex, facial numbness, and mastication weakness, was lower in the craniotomy group than the PBC and RFT groups (P < 0.001). The 5-year pain recurrence rate was significantly higher than the 1-year rate in all groups. Although the 1-year pain recurrence rate did not differ among the groups, the 5-year rate was significantly lower in the repeat craniotomy group than the other groups (P < 0.001).

CONCLUSION

Patients with recurrent trigeminal neuralgia after MVD should be treated based on imaging evaluation and general condition. Repeat craniotomy, PBC, and RFT are all effective. Incidence of postoperative complications and long-term pain recurrence-free survival are superior for repeat craniotomy.

Erenumab in the Treatment of Comorbid Trigeminal Neuralgia in Patients With Migraine

Background Surgical treatment for trigeminal neuralgia (TN) sometimes becomes difficult. Erenumab, an anti-calcitonin gene-related peptide (CGRP)-receptor monoclonal antibody, is used for migraine and potentially has efficacy for TN. Method We retrospectively investigated six migraine patients with comorbidity treated with 70 mg of erenumab. Monthly headache days and a numerical rating scale (NRS) of TN were evaluated before, one, and three months after erenumab administration. Results Before being treated with 70 mg of erenumab, the six migraine patients with comorbid TN had taken at least one sort of preventative medication, but it had been ineffective. During the three-month erenumab use, previous medications were continued. The median age was 71 years (range 59-87). The six patients (five females and one male) had episodic migraine. Three had TN due to vessels, one had TN due to a tumor, one had TN without neurovascular compression, and one had an undetermined etiology. Five (83%) of the six patients reported improved NRS of TN. The median NRS of TN before, one, and three months after treatment were 8 (7-10), 3.5 (0-10), and 2 (0-5, n=4). Monthly headache days were 4 (4-10), 2.5 (0-4), and 1 (1-2, n=4). There were no side effects of erenumab. Conclusion Surgical treatment sometimes cannot be performed for those with TN. Our findings were preliminary and a bigger sample size is required for this study to draw firmer conclusions. However, it is possible, although rare, that there are migraine patients for whom the NRS of comorbid TN improves with the use of erenumab, an anti-CGRP receptor monoclonal antibody.

Internal neurolysis versus intraoperative glycerin rhizotomy for trigeminal neuralgia

OBJECTIVE

Internal neurolysis (IN) and intraoperative glycerin rhizotomy (ioGR) are emerging surgical options for patients with trigeminal neuralgia without neurovascular contact. The objective of this study was to compare the neurological outcomes of patients who underwent IN with those of patients who underwent ioGR.

METHODS

The authors retrospectively reviewed all patients who underwent IN or ioGR for trigeminal neuralgia at our institution. Patient demographic characteristics and immediate postoperative outcomes, as well as long-term neurological outcomes, were compared.

RESULTS

Of 1044 patients who underwent open surgical treatment for trigeminal neuralgia, 56 patients underwent IN and 91 underwent ioGR. Of these 147 patients, 37 had no evidence of intraoperative neurovascular conflict. All patients who underwent IN and 96.7% of patients who underwent ioGR had immediate postoperative pain relief. At last follow-up, patients who underwent IN had lower Barrow Neurological Institute (BNI) pain intensity scores (p = 0.05), better BNI facial numbness scores (p < 0.01), and a greater degree of pain improvement (p = 0.05) compared with those who underwent ioGR. Patients who underwent IN also had significantly lower rates of symptomatic pain recurrence (p < 0.01) at last follow-up over an average of 9.5 months.

CONCLUSIONS

IN appears to provide patients with a greater degree of pain relief, lower rates of facial numbness, and lower rates of pain recurrence compared with ioGR. Future prospective studies will better characterize long-term pain recurrence and outcomes.

MRI Findings in Trigeminal Neuralgia without Neurovascular Compression: Implications of Petrous Ridge and Trigeminal Nerve Angles

Objective

To determine the anatomical characteristics of the petrous ridge and trigeminal nerve in trigeminal neuralgia (TN) without neurovascular compression (NVC).

Materials and Methods

From May 2017 to March 2021, 66 patients (49 female and 17 male; mean age ± standard deviation [SD], 56.8 ± 13.3 years) with TN without NVC and 57 controls (46 female and 11 male; 52.0 ± 15.6 years) were enrolled. The angle of the petrous ridge (APR) and angle of the trigeminal nerve (ATN) were measured using magnetic resonance imaging with a high-resolution three-dimensional T2 sequence. Data on the symptomatic side were compared with those on the asymptomatic side in patients and with the mean measurements of the bilateral sides in controls. Receiver operating characteristic (ROC) analysis was conducted to evaluate the performance of APR and ATN in distinguishing TN patients from controls.

Results

In TN patients without NVC, the mean ± standard deviation (SD) of APR on the symptomatic side (98.40° ± 19.75°) was significantly smaller than that of the asymptomatic side (105.59° ± 22.45°, p = 0.019) and controls (108.44° ± 15.98°, p = 0.003). The mean ATN ± SD on the symptomatic side (144.41° ± 8.92°) was significantly smaller than that of the asymptomatic side (149.67° ± 8.09°, p = 0.003) and controls (150.45° ± 8.48°, p = 0.001). The area under the ROC curve for distinguishing TN patients from controls was 0.673 (95% confidence interval [CI]: 0.579–0.758) for APR and 0.700 (CI: 0.607–0.782) for ATN. The sensitivity and specificity using the diagnostic cutoff yielding the highest Youden index were 81.8% (54/66) and 49.1% (28/57), respectively, for APR (with a cutoff score of 94.30°) and 65.2% (43/66) and 66.7% (38/57), respectively, for ATN (cutoff score, 148.25°).

Conclusion

In patients with TN without NVC, APR and ATN were smaller than those in controls, which may explain the potential cause of TN and provide additional information for diagnosis.

Identifying symptomatic trigeminal nerves from MRI in a cohort of trigeminal neuralgia patients using radiomics

INTRODUCTION

Trigeminal neuralgia (TN) is a devastating neuropathic condition. This work tests whether radiomics features derived from MRI of the trigeminal nerve can distinguish between TN-afflicted and pain-free nerves.

METHODS

3D T1- and T2-weighted 1.5-Tesla MRI volumes were retrospectively acquired for patients undergoing stereotactic radiosurgery to treat TN. A convolutional U-net deep learning network was used to segment the trigeminal nerves from the pons to the ganglion. A total of 216 radiomics features consisting of image texture, shape, and intensity were extracted from each nerve. Within a cross-validation scheme, a random forest feature selection method was used, and a shallow neural network was trained using the selected variables to differentiate between TN-affected and non-affected nerves. Average performance over the validation sets was measured to estimate generalizability.

RESULTS

A total of 134 patients (i.e., 268 nerves) were included. The top 16 performing features extracted from the masks were selected for the predictive model. The average validation accuracy was 78%. The validation AUC of the model was 0.83, and sensitivity and specificity were 0.82 and 0.76, respectively.

CONCLUSION

Overall, this work suggests that radiomics features from MR imaging of the trigeminal nerves correlate with the presence of pain from TN.

External Neurolysis in Microvascular Decompression for Magnetic Resonance Imaging-Negative Idiopathic Trigeminal Neuralgia

OBJECTIVE

Internal neurolysis has been proposed as an alternative to microvascular decompression in patients with idiopathic trigeminal neuralgia (TN) in whom neurovascular compression is not confirmed by magnetic resonance imaging (MRI). External neurolysis, which straightens and realigns the trigeminal nerve root axis by dissecting the arachnoid membranes around the nerve, was reported 20 years ago in the context of so-called negative exploration when MRI did not confirm the absence of the offending vessel, but is not currently used.

METHODS

External neurolysis was performed in 4 patients with idiopathic TN with typical evoked neuralgic pain despite the absence of suspected offending vessels on MRI. The surgical findings that caused TN were summarized and the outcomes were evaluated using the Barrow Neurological Institute Pain Intensity Scale (BNI-PS).

RESULTS

Tethering and distortion of the nerve root by surrounding arachnoid membranes were commonly found. All 4 patients showed complete pain relief immediately after surgery. During the follow-up period of 26.5 ± 16.92 months (±standard deviation), 3 of 4 patients had no pain (score I, BNI-PS). One patient received a score of IIIa on the BNI-PS assessment. There was no instance of recurrence or side effects associated with the surgery.

CONCLUSIONS

Idiopathic TN can be induced by individual variation of the surrounding inner arachnoid membranes supporting the trigeminal nerve root, and the condition cannot be identified by MRI. Intradural external neurolysis may be considered an effective treatment for MRI-negative idiopathic TN.

Diffusion tensor imaging reveals microstructural alteration of the trigeminal nerve root in classical trigeminal neuralgia without neurovascular compression and correlation with outcome after internal neurolysis

OBJECTIVES

Diffusion tensor imaging (DTI) has been used to detect microstructural alteration and effect of surgical treatment of the trigeminal nerve root (TR) in patients with classical trigeminal neuralgia (CTN) underwent microvascular decompression (MVD). Patients with CTN without neurovascular compression (woNVC) is a special population of TN, however, the pathogenesy of CTN woNVC and the mechanism of internal neurolysis (IN) remain unknown.

MATERIALS AND METHODS

21 patients with CTN woNVC who underwent IN and 20 healthy controls were included in this study. The differences in the means, kurtosis and skewness of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) between the affected and unaffected nerves in patients and both nerves in controls were investigated by independent t-test and paired t-test respectively. Longitudinal changes of FA and ADC were correlated with outcome of IN via Spearman correlation coefficient.

RESULTS

Significant differences were found in preoperative mean and kurtosis values for both FA and ADC of the affected side TR, compared to the unaffected side and control group respectively. However, these differences remarkably reduced postoperatively. Further, the Spearman correlation coefficient showed a strong negative correlation between decrease of ADC in the affected side and the surgical outcome in BNI total score.

CONCLUSION

The changes of diffusive property of TR, especially the FA and ADC, provide alternative radiological evidence for evaluating the mechanism of CTN woNVC. The modification of DTI metrics could be an effective factor for providing potential noninvasive biomarkers for determining the prognosis of patients with CTN woNVC underwent IN.

Treatment Outcomes in Trigeminal Neuralgia-A Systematic Review of Domains, Dimensions and Measures

BACKGROUND

Trigeminal neuralgia (TN) is a painful disorder characterized by sudden electric shock-like pain. It is a rare condition for which multiple treatments are available, including medical and surgical. The best treatment option is yet to be defined, and this is related to the lack of definition in the treatment outcomes and outcome measures. The aim of this systematic review was to summarize all the outcomes and outcomes measures that have been published to date and highlight variability in their use.

METHODS

We have conducted a literature search using a wide range of databases (1946-2019 for medical and 2008-2019 for surgical treatment), for all intervention studies in TN. Four hundred and sixty-seven studies were selected for data extraction on TN classification, data collection method, intervention, and treatment outcomes mapped to the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT guidelines).

RESULTS

Most studies collected data on pain (n = 459) and side effects (n = 386) domains; however, very few collected data on the impact of treatment on physical (n = 46) and emotional functioning (n = 17) and on patient satisfaction (n = 35). There was high variability on outcome measures used for pain relief (n = 10), pain intensity (n = 9), and frequency of pain episodes (n = 3).

CONCLUSIONS

A clear definition of what are the important outcomes for patients with TN is essential. The choice of standardized outcome measures allowing for consistent reporting in TN treatment will allow for comparison of studies and facilitate treatment choice for patients and clinicians thus, improving health outcomes and reducing health care cost.

Microvascular Decompression for Trigeminal Neuralgia in Patients with Multiple Sclerosis: Predictors of Treatment Success

BACKGROUND

Microvascular decompression (MVD) is highly effective in managing the neuropathic facial pain of trigeminal neuralgia (TN). Its utility in patients with TN and concurrent multiple sclerosis (MS) has been a subject of debate. The goal of this study was to identify demographic and perioperative variables associated with favorable outcome after MVD over the past 20 years in patients from our institution.

METHODS

A retrospective analysis of our cohort of 33 patients diagnosed with MS and TN who underwent MVD between 1997 and 2017 to treat neuropathic facial pain was performed. Perioperative variables included MS disease burden, findings on preoperative magnetic resonance imaging (MRI), TN pain severity, and the presence of intraoperative neurovascular compression. MS disease burden was quantified using the Expanded Disability Status Scale. Preoperative and postoperative pain severity was quantified using the Barrow Neurological Institute (BNI) pain severity scale.

RESULTS

A total of 33 patients with TN and MS were treated with MVD at our institution (out of the 632 total MVDs performed) between 1997 and 2017. Twenty-two patients (67%) maintained a reduction in pain at a mean follow-up of 53.5 months. Higher preoperative BNI pain intensity score was associated with unfavorable outcome after MVD (P = 0.006). No associations were identified between MS disease burden, presence of neurovascular compression or pontine demyelinating plaques on MRI, or intraoperative findings of neurovascular compression and treatment outcomes.

CONCLUSIONS

MVD is a reasonable treatment option for patients with TN and MS, although the rate of freedom from pain is lower than that for the general TN population. Preoperative pain severity may be a predictor of treatment success.

Atypical spinal endodermal cyst presenting with contralateral C2 neuralgia and aseptic meningitis

A previously healthy 43-year-old man presented with durable occipitalgia for 1 month. Neurological examination revealed severe pain in the right C2 area accompanied by neck stiffness. Magnetic resonance imaging revealed an enhancing, polycystic intradural mass at the C2 level, occupying the left dorsolateral part of the spinal canal. In addition, a rim-like enhancement was found along the surfaces of the spinal cord. Blood tests did not show signs of infection. A lumbar spinal tap revealed albuminocytologic dissociation without cultured organisms. Cranial computed tomography scans taken 20 days later revealed an overt ventriculomegaly. The patient underwent a total tumor resection through hemilaminectomy of the C2. Intraoperatively, the left dorsal C2 roots were found to be extremely redundant due to the tumor and surrounding thickened arachnoids. The roots restored normal morphologies after resection of the arachnoids and tumor. Postoperatively, the patient's symptoms resolved and histological diagnosis was endodermal cyst. Four weeks later, a ventriculoperitoneal shunt was placed to treat progressive ventriculomegaly. A polycystic intradural mass of the upper cervical spine should assume an endodermal cyst that may cause contralateral occipitalgia and aseptic meningitis.