Efficacy and Safety of Computed Tomography-Guided Percutaneous Balloon Compression under Local Anesthesia for Recurrent Trigeminal Neuralgia: A Prospective Study

Purpose There are several ways to treat trigeminal neuralgia (TN); however, TN may recur after treatment. This study investigated the efficacy and safety of computed tomography (CT)-guided percutaneous balloon compression (PBC) under local anesthesia for treatment of recurrent trigeminal neuralgia. Patients and Methods. This is a prospective and nonrandomized controlled clinical study. Forty-eight patients with classical TN were scheduled to undergo PBC surgery at the pain department of our institution between January 2021 and June 2021. The patients were prospectively divided into an initial onset group, A (21 cases), and a recurrence group, B (27 cases). All surgeries were performed with CT guidance and under local anesthesia. Postoperative complications were also observed. Pain was assessed using the visual analog scale (VAS) and Barrow Neurological Institute (BNI) scale. Efficacy indices were evaluated at 3, 6, 12, and 18 months after surgery. Results All participants reported complete pain relief at discharge. After 18 months of follow-up, the total effective rate of pain control was 89.5% (group A, 90.5%; group B, 88.8%). There was no significant difference in the BNI scores between the two groups before and after treatment. All patients had hypoesthesia on the affected side, and no severe complications such as diplopia, blindness, intracranial hemorrhage, or intracranial infection occurred. Conclusions CT-guided PBC under local anesthesia is safe and effective for the treatment of recurrent TN and thus acts as an effective alternative for geriatric patients and those with high-risk factors.


Introduction
Trigeminal neuralgia (TN) is one of the most painful diseases, characterized by recurrent, unilateral, transient but severe, electrocution like pain with rapid onset and short duration (up to several minutes) [1].It can occur when talking, washing, or eating, followed by sudden cessation of pain and reappearance after the next stimulus.Te patient's quality of life is severely reduced.According to the International Classifcation of Headache Disorders 3rd edition (ICHD-3), TN can be classifed into three subgroups: classical TN, secondary TN, and idiopathic TN [2].Several treatments for classical TN are available and have been repeatedly reported for patients with poor pain control [3,4], but these treatments only briefy manage the pain and do not prevent recurrence.Microvascular decompression (MVD) is currently considered to provide the lowest recurrence rate; however, following recurrence, patients are often reluctant to undergo another craniotomy, and MVD is not suitable for older patients or those with poor health.Terefore, PBC can replace microvascular decompression in older patients [5].
Percutaneous balloon compression (PBC) has been shown to be efective in treating TN.In 1983, Mullan and Lichtor performed PBC for the frst time to treat TN [6].Efcacy and safety of awake computed tomography (CT)guided PBC of the trigeminal ganglion for the treatment of TN has been reported [7,8].Its advantages include sufcient nerve damage, no need to distinguish the responsible nerve, and simple and safe operation.When the balloon catheter enters the Meckel's cavity, the trigeminal nerve semilunar ganglion is compressed by the balloon for approximately 1-3 minutes.Te balloon is then released, and the balloon catheter is removed.After the trigeminal ganglion is damaged by compression, an analgesic efect is achieved in the innervated area.
PBC is usually performed under general anesthesia and C-arm guidance, which poses a great risk to patients with respiratory or cardiovascular complications and a high incidence of trigeminal cardiac refex (TCR).Trigeminal ganglion block-assisted deep sedation can reduce the occurrence of serious complications [9].Tis study was performed under local anesthesia.By comparing PBC in the treatment of primary and recurrent TN, we explored the efcacy and safety of CT-guided PBC under local anesthesia for the treatment of recurrent trigeminal neuralgia.2.2.Surgery.Te procedure of surgery has been described previously [10].Te patient remained awake during the operation and was placed in the supine position with the head tilted backward.ECG monitoring was routinely performed to monitor blood pressure, heart rate, and oxygen saturation.Midazolam 0.03 mg/kg was slowly injected intravenously for sedation before surgery.A 22G local anesthesia needle with a length of 10 cm was used for the puncture.Under CT guidance, 1% lidocaine (0.5 mL) was injected into the foramen ovale of the trigeminal nerve ganglia to block the nerves (Figure 2).Te guidewire was then placed into the local anesthesia needle, the local anesthesia needle was withdrawn, and a 14G balloon puncture needle was placed along the guidewire.When the needle was advanced into the foramen ovale, a No. 4 Fogarty balloon catheter was inserted along the balloon catheter needle.After confrming the proper location, 0.5-0.8ml iohexol was injected into the catheter to infate the end balloon.During the CT scan of the lateral head, the balloon and position were adjusted until a pear-shaped image was obtained (Figure 3).After 1.5-2.5 min of compression (group A, 1.5 min; group B, 2.5 min), the balloon was withdrawn.

Terapeutic Assessment and Follow-Ups. Te Barrow
Neurological Institute (BNI) scale and visual analog scale (VAS) were used to assess the degree of pain.Complications and pain recurrences were also recorded.Te BNI scale assessed the pain intensity in patients, as shown in Table 1.A BNI Pain Intensity Score of I-II and a VAS score of <3 were considered efective.Patients were followed up for 3, 6, 12, and 18 months after surgery, and their pain and numbness were recorded.

Statistical Analysis. SPSS 24 software and GraphPad
Prism 8 were used for statistical analyses.After analysis, all variables were normally distributed.Te sample size was calculated using the G * power software (Heinrich-Heine-University Düsseldorf, version 3.1.9.4,Düsseldorf, Germany).We assumed that the efect size for the main outcome of the efective rate was 0.45, the alpha error at 0.05, and the  2 Pain Research and Management power at 0.80, considering 20% dropout rate; thus, 48 participants were recruited in study.Te data were presented as mean ± standard deviation.Categorical variables were analyzed using χ 2 test or Fisher exact probability test, and continuous variables were analyzed using variance analysis of repeated measurement data.P < 0.05 was considered to be statistically signifcant.According to the BNI, the rate of pain relief (BNI I-II) within 6 months in groups A and B reached 100%.In group A, the pain recurred in one case (4.7%) within 12 months; in group B, the pain recurred in two cases (7.4%), P � 0.595.In group A, pain recurrence occurred in two cases (9.5%); in group B, pain recurrence occurred in three cases (11.1%) within 18 months, P � 0.621.2. Te postoperative BNI scores in groups A and B were signifcantly improved compared to those before surgery, as shown in Figure 4.

Discussion
TN is one of the most painful diseases.Te prevalence rate of TN is from 4 up to 29 cases per 100,000 person-years [11].
Although the pathophysiological mechanism is not clear [12], various efective surgical treatments for TN have been applied, such as MVD, PBC, and radiofrequency thermocoagulation of the trigeminal semilunar ganglion.It has been reported that these treatments can achieve substantial curative efects but also have certain recurrence rates.
In terms of minimally invasive treatment of TN, the rate of pain relief after PBC was similar to that reported after PRT and higher than that of GKRS [13,14].PBC has a relatively low TN recurrence rate of approximately 20% within 5 years and 32% within 20 years, along with a patient-reported satisfaction rate of 70% [15,16].Tus, it could be preferentially recommended for patients undergoing ablative procedures [17].Moreover, the technique provides a more stable and efective means of nerve injury without craniotomy and avoids the occurrence of serious complications to a large extent.Te mechanism of PBC involves damaging the large and medium myelinated nerve fbers that transmit pain and preserving the unmyelinated nerve fbers that transmit to the corneal refex [18].
General anesthesia can provide patients with a more comfortable feeling [19,20].However, when the balloon compresses the trigeminal ganglion, TCR often occurs, leading to a sharp drop in blood pressure and heart rate, and even causing cardiac arrest.Wang et al. reported that atropine pretreatment before compression of the trigeminal nerve ganglion was more reasonable in preventing signifcant hemodynamic changes [21].We found in the clinic that the incidence of blood pressure drop in patients was still high even after preoperative preconditioning.Local anesthesia blocks TCR from occurring and maintains stable blood pressure and heart rate [22].Tere was no signifcant diference in blood pressure and heart rate before and during surgery.Te needle location was carefully monitored.If the tip is too deep, the anesthetic may be injected into the Meckel's cavity, causing serious consequences.Tis should be avoided and therefore precise positioning is required.
To date, CT-guided surgery is the best strategy for improving surgical safety.Tree-dimensional (3D) imaging reconstruction produces more efcient and safer results than two-dimensional imaging [23].Tis method has been widely used in PRT.However, for PBC, most of the surgery is still carried out under the C-arm.In our operations, we occasionally encounter anatomical anomalies such as skull defcit or the integration of the foramen ovale and the foramina spinosum.Under the C-arm, these conditions may be overlooked and serious consequences may occur intraoperatively.Preoperative 3D imaging reconstruction of the skull base is helpful in fnding anatomical variations and avoiding inadvertent damage to the peripheral neurovascular structure [24].Te location of the foramen ovale and the depth of penetration of the cannula are visible, which gives the surgeon confdence and greatly improves patient safety.In addition, in patients with a bony protrusion around the foramen ovale, which prevents successful intubation using conventional techniques, 3D reconstruction is more efective and accurate than other techniques.Our operations were all completed under CT and are, therefore, diferent from traditional operations.
We have accumulated rich experience in PRTunder local anesthesia and believe that PBC can also be completed under local anesthesia.Adequate anesthesia is of the utmost importance, and the injection site of the anesthetic drug must be ensured at the trigeminal ganglion.Pay attention to slow injection, repeatedly withdraw the syringe, to ensure that there is no blood and cerebrospinal fuid.During the operation, 1% lidocaine hydrochloride (0.5 mL) was injected into the trigeminal ganglion to inhibit TCR and improve safety.During the entire process, the patient was awake, and discomfort could be reported in a timely manner, which was convenient for the administration of the corresponding treatment and efectively avoided serious complications such as double vision and oculomotor nerve palsy.Local anesthesia surgery is more suitable when the patient is older or in poor health and cannot use general anesthesia.
Numbness is the most common complication of PBC.Studies have shown that the incidence of facial hypoesthesia after balloon compression is more than 90% [25].Although patients in group B may have had symptoms of numbness as a result of damaging treatments such as radiofrequency thermocoagulation and glycerol injection, the numbness was signifcantly relieved when the pain recurred.After PBC, the range and degree of numbness increased signifcantly, which was also related to the location of PBC in the trigeminal Pain Research and Management ganglion.In patients with recurrence, we extended the compression time and intensity, which made the subjective feeling of postoperative numbness more obvious.Increased duration and degree of compression also increased the incidence of masticatory muscle weakness on the afected side.Twelve patients showed symptoms of masticatory weakness, all of whom recovered within 6 months.
After 18 months of follow-up, we compared the efcacy between groups A and B and found that the total efective rate of pain control was 89.5% (group A, 88.8%; group B, 90.4%).Tere was no statistically signifcant diference in the postoperative efcacy between the two groups.Tis suggests that treatment in both groups was safe and efective.Te preoperative and postoperative VAS scores difered significantly between the two groups.All patients developed hypoesthesia in the skin and mucosa of the afected side immediately after surgery, presenting a primary complication.Temporary postoperative discomfort, such as headache, dizziness, and nausea or vomiting, was associated with irritation of the surrounding tissues or nerves during the surgical procedure.All the symptoms resolved after rest.No intracranial hemorrhage, intracranial infection, or other serious complications occurred in either group, indicating that PBC was safe and efective.
Tis was a single-center study with a small sample size and a short follow-up period of 18 months.Te determination of the long-term efcacy of PBC in the treatment of postoperative recurrent TN requires a larger sample size, longer follow-up time, and multicenter evaluation.

Conclusion
CT-guided PBC under local anesthesia is safe and efective for treating recurrent TN.Tis approach provides a safe and efective alternative for older patients and those with highrisk factors.

2. 1 .
Study Design and Participants' Population.Tis is a prospective and nonrandomized controlled clinical study.From January 2021 to June 2021, we enrolled 48 patients with TN in the pain department of our institution.All patients were diagnosed with classical TN, with one or more afected trigeminal branches.Te study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of our institution (2020-R562).Written consent was obtained from all participants in this study.All surgeries were performed by the same surgeon, and the medical records of all patients were collected and analyzed.Te patients were divided into an initial onset group, A (21 cases), and a recurrence group, B (27 cases).A fowchart of the entry and exit of patients is shown in Figure 1.All surgeries were performed with CT guidance and under local anesthesia.Te inclusion criteria were as follows: (1) defnite diagnosis of classical TN; (2) age between 30 and 90 years; and (3) a visual analog scale (VAS) score ≥4 points.On the other hand, the exclusion criteria were as follows: (1) age <30 years or >90 years; (2) local infection at the puncture site; (3) coagulopathy or hemorrhagic disease; (4) mental illness preventing cooperation; and (5) severe heart, brain, lung, and liver diseases.

Figure 1 :
Figure 1: Flowchart of inclusion of trigeminal neuralgia patients.

Figure 2 :
Figure 2: If the foramen ovale is small, it will cause difculty in piercing.Ct-guided needle puncture signifcantly improved the accuracy.Te injection of anesthetics into Meckel's cavity should be avoided during local anesthesia, and the 3D digital imaging technology can clarify the tip location and improve the safety.

Figure 3 :
Figure 3: Te location of the balloon catheter can be determined by inserting the balloon catheter under CT guidance.After the iohexol was injected, a "pear-shaped image" was displayed on lateral CT imaging, indicating successful surgery.
Demographics.Tis is a prospective and nonrandomized controlled clinical trial study.Tere were 48 patients (20 males and 28 females).Ages ranged from 35 to 89 years (mean 61.81 ± 13.38 years).Te disease duration ranged from 0cant diferences in sex (P � 0.942), age (P � 0.107), VAS scores (P � 0.643), or BNI scores (P � 0.777) between groups A and B. Te blood pressure and heart rate remained stable.All patients underwent microballoon compression and dilation of the trigeminal nerve; fve patients still had postoperative pain, which disappeared 7 days after repeated surgery.

Table 2 :
Patient demographics and clinical data.

Table 3 :
Comparison of VAS score in the two groups.