Efficacy and safety of percutaneous balloon compression for bilateral trigeminal neuralgia： a retrospective study

doi:10.21203/rs.3.rs-3758744/v1

Background Percutaneous balloon compression（PBC）of the Gasserian ganglion is steadily gaining traction within the trigeminal neuralgia（TN）community. Bilateral trigeminal neuralgia（BTN） is a rare condition, and its treatment remains challenging. As far as we know, there are currently no research reports on the treatment outcomes of PBC for BTN.The purpose of this study is to meticulously evaluate the efficacy and safety of PBC for BTN in our medical institution.

Methods In this retrospective study, we collected and analyzed the medical records of all patients with BTN who underwent the PBC procedure at the Department of Neurosurgery at Hebei General Hospital from July 2017 to July 2023. After undergoing PBC therapy, all patients were promptly assessed for treatment efficacy based on the modified Barrow Neurological Institute (BNI) pain intensity grading scale.

Results All 37 patients with BTN experienced significant pain relief (BNI I-IIIb) immediately following unilateral PBC treatment. Among these patients, 25 reported relief from pain on the non-operative side, which was effectively managed with medication. Out of the 12 patients who did not experience improvement in contralateral symptoms, 11 received contralateral PBC. Out of the 48 treated sides, 47 sides (97.9%) achieved excellent pain control following a single PBC procedure. The follow-up times ranged from 2 to 62 months.The cumulative survival after PBC was 100%, 90.2%, and 80.2% within 1, 3, and 5 years, respectively.Three recurrent patients underwent repeated unilateral PBC, and all of them maintained excellent pain control postoperatively. At the last follow-up, satisfaction was at 91.7% (measured using the Likert scale), with no severe complications occurring.

Conclusions The results indicate that PBC is an effective and relatively safe method for treating BTN, offering a valuable option for pain control in these rare cases of TN.

Bilateral

Trigeminal neuralgia

Percutaneous balloon compression

recurrence rate

complications

satisfaction

Trigeminal neuralgia (TN) is one of the common clinical cranial nerve disorders, characterized by recurrent paroxysms of sudden, lightning-like, electric-shock-like, tearing, and stabbing pain within the distribution of the trigeminal nerve[1], with a global prevalence of 4–5 per 100,000[2].BTN is a rare condition, and it has been reported to have an incidence of 1–6% in larger series studies[3–5].The exact pathogenesis of BTN remains unclear, but it may be associated with conditions such as multiple sclerosis (MS), poliomyelitis, Paget's disease, etc. [6, 7]. Currently, there is no treatment consensus for BTN.The treatment approach for BTN is similar to that of unilateral TN,and drug therapy is the first-line treatment option [8, 9].When drug therapy is ineffective or the side effects of medication are intolerable, surgical treatment may be considered.

Surgical treatments mainly include microvascular decompression (MVD), radiofrequency ablation, gamma knife radiosurgery, and PBC. Different surgical approaches yield varied favorable outcomes[26]. MVD offers a successful treatment option for BTN patients, but it involves the posterior fossa, posing a higher risk of complications such as meningitis and death[7, 9]. Radiofrequency ablation is relatively simple and safe, with a high initial relief rate, but it has a higher early (within 6 months) pain recurrence rate[13]. Gamma knife radiosurgery can be used to treat patients with BTN ,with low invasiveness[17]. However, it has a low success rate, high recurrence rate, and a latent period for postoperative pain relief compared to other surgeries. Therefore, in clinical practice, gamma knife radiosurgery is often considered as a salvage treatment option. Currently, PBC has gained popularity among TN patients, especially those who are not suitable for or refuse MVD[10]. PBC was first described by Mullan and Lichtor in 1983[11]. Its unique advantage is being the only percutaneous technique for treating TN under general anesthesia. The correct positioning of the balloon and its characteristic "pear-shaped" form are considered crucial for the success of the procedure. Its main advantages include a high postoperative success rate[12], a low 5-year recurrence rate of only 20%[13], and a low incidence of complications[14]. Additionally, if the pain recurs, the procedure can be safely and effectively repeated.However, to our knowledge, there have been no prior reports on the treatment outcomes of PBC for BTN. This study retrospectively reports our institution's experience with the use of PBC for treating BTN and evaluates its effectiveness and safety.

Patient Population

From July 2017 to July 2023, a total of 904 patients with TN underwent PBC treatment in the Department of Neurosurgery at Hebei General Hospital. Among them, 37 cases were BTN patients.This study obtained approval from the hospital's ethics committee. Due to the retrospective nature of this study, informed consent was not required.

Criteria for Selection

Inclusion criteria: (1) All patients exhibited characteristic symptoms of typical TN, conforming to the diagnostic criteria of the 3rd edition of the International Classification of Headache Disorders published in 2013[15]; (2) Preoperative pain assessment score on the Visual Analog Scale (VAS) > 5; (3) Inadequate pain control or intolerance to medication therapy for pain before PBC procedure; (4) Received PBC procedure; Exclusion criteria: (1) Patients with atypical TN or secondary TN caused by intracranial lesions; (2) TN patients who cannot tolerate general anesthesia due to poor physical condition; (3)TN patients who do not undergo PBC due to their inability to tolerate potential complications such as facial numbness and weakened chewing muscles; (4)Patients with incomplete follow-up data.

Percutaneous balloon compression

All surgeries were performed under brief general anesthesia with endotracheal intubation.Patients were placed in a supine position with the head tilted back at an angle of 10°-15°, while ensuring alignment of both external auditory canals.After routine disinfection and draping with sterile sheets, a 14-gauge puncture needle (CTZ-14; Qingyuan Company, Shenzhen, China) was used to puncture the outer corner of the mouth at a distance of 2.5-3 centimeters.Under the guidance of DSA, a puncture needle is inserted into the outer opening of the foramen ovale. The needle core is removed, and a gas-filled 4F Fogarty balloon catheter (QK08S50; Qingyuan Corporation, Shenzhen) is inserted into the Meckel's cave of the trigeminal nerve. Subsequently, the surgeon injects 0.3-1ml of iohexol at a concentration of 120mg/ml, inflates the balloon to a pear shape (Fig. 1), applies pressure for 100-120 seconds, then removes the contrast medium, the puncture needle, and the balloon catheter, concluding the procedure.During foramen ovale puncture, bradycardia may occur. Atropine can be used if necessary. Hypertension can also occur concurrently with bradycardia; antihypertensive medication should be administered if necessary. Patients are typically discharged within 24 hours after the surgery.

Follow-up and Outcome Assessment

The data was collected through electronic medical records, outpatient visits, or telephone follow-up surveys. Each treatment arm was assessed separately, and the results were based on the total count within each treatment arm. The initial assessment was obtained on the first day after surgery. All patients were followed up monthly either by phone or through outpatient visits. Postoperative pain relief status, occurrences of complications, and patients' satisfaction with the PBC procedure were captured. Preoperative pain was assessed using the VAS score, while postoperative treatment effectiveness was evaluated using the Barrow Neurological Institute (BNI) Pain Intensity Grading Scale (Table 1). Excellent outcomes were defined as BNI I-II, good outcomes as BNI IIIa-IIIb, ineffective treatment as BNI IV-V, and recurrence was defined as an increase from BNI I-III to IV-V. The Barrow Neurological Institute (BNI) Facial Numbness Grading Scale was employed to assess facial numbness (Table 2). Patient satisfaction was graded using the Likert scale (Table 3), where levels 1-3 indicated dissatisfaction with the treatment, and levels 4-5 indicated satisfaction with the treatment.

Statistical Analysis

All data were analyzed using the Social Sciences Statistical Package version 22.0 (SPSS Inc., Chicago, Illinois, USA).The chi-square test was used to assess the statistical significance of differences in demographic and clinical parameters between unilateral and bilateral TN patients. Categorical variables are represented as frequency values, while continuous variables are represented as mean ± standard deviation. The Kaplan-Meier method was employed to evaluate the cumulative recurrence-free survival period. The statistical significance level was set at p < 0.05.

A total of 904 patients with TN who underwent PBC surgery at our institution from July 2017 to July 2023 were retrospectively reviewed. Among them, 37 cases were BTN , with a BTN occurrence rate of 4.1%.Table 4 presents the characteristics of patients with unilateral and bilateral TN. In comparison to unilateral TN, the proportion of females is higher among those with BTN, indicating a greater likelihood of it being hereditary. Additionally, the incidence of concurrent cranial nerve dysfunction is higher among patients with BTN. The proportion of patients with hypertension is similar in both groups.

Table 5 displays the clinical and surgical characteristics of 37 patients with BTN. Among the 37 patients with BTN, 18 cases were initially affected on the right side, accounting for 48.6%; 13 cases were initially affected on the left side, accounting for 35.1%; 6 patients simultaneously exhibited symptoms on both sides. In our study, the average time for the development of contralateral symptoms was 7.8±7.4 years. The follow-up duration varied from 2 to 62 months, with an average follow-up time of 23.7±15.6 months.Follow-up statistical data is displayed in Table 6.

In this study, 26 patients underwent unilateral PBC surgery, while 11 patients underwent bilateral PBC surgery. In the entire series of BTN cases (including patients who underwent unilateral and bilateral PBC surgery), 35 patients had their surgical side pain vanish immediately and discontinued medication following unilateral treatment, with one patient occasionally experiencing pain without needing oral carbamazepine, and another patient remaining pain-free after carbamazepine medication.Interestingly, pain on the non-surgical side was alleviated in 25 patients, achieving effective control of pain through medication. Among the 12 patients whose contralateral symptoms did not improve, 11 patients underwent a second PBC surgery on the contralateral side, with a mean interval between surgeries of 21.4±12.6 months (ranging from 3 to 50 months). Out of the 48 treated sides, 47 sides (97.9%) achieved excellent pain control following a single PBC procedure. During the final follow-up, pain relief was still considered satisfactory in 34 patients (43 operative sides). Three patients (3 operative sides) experienced recurrences at 13 months，32 months and 37 months postoperatively, respectively. They underwent a second PBC surgery at our institution, achieving excellent long-term results with no further recurrence.We presented the recurrence-free duration (BNI grades I–IIIb) as a Kaplan-Meier curve in Fig. 2. The cumulative survival after PBC was 100%, 90.2%, and 80.2% within 1, 3, and 5 years, respectively.

During long-term follow-up, facial numbness occurred in 46 operative sides after PBC surgery. Among them, 40 cases experienced mild numbness (BNI grade II), and 6 cases had moderate numbness (BNI grade III). Most patients recovered within 1 year, with no instances of severe numbness reported. Nineteen operative sides experienced masticatory muscle weakness, and all patients recovered within 3-6 months. There were no cases of persistent masticatory muscle weakness, inability to recover from it, or simultaneous bilateral occurrence of masticatory muscle weakness affecting eating.One patient experienced decreased corneal sensation, which recovered within 2 weeks; seven patients developed herpes zoster around the oral region, with all patients seeing resolution within 1-2 weeks. No severe complications such as blindness, carotid-cavernous fistula, intracranial hemorrhage, or percutaneous balloon compression procedure-related deaths occurred among all patients.Upon discharge, all patients expressed satisfaction with the treatment results. During long-term follow-up, as more patients experienced complications and recurrences, the level of patient satisfaction decreased. In the final follow-up, satisfaction was at 91.7%.

BTN is a rare condition. In our study, the incidence of BTN was 4.1%, which aligns with the range of incidence reported in various large-scale case studies (0.6-5.9%). Compared to our own unilateral TN, BTN has a higher proportion of females, a higher proportion of familial cases, and additional cranial nerve dysfunction, consistent with the findings of Ami et al. and Tacconl et al [16-18]. In our series, there was no significant difference in the proportion of unilateral and bilateral TN cases associated with hypertension.Furthermore, we observed that in patients with BTN, pain rarely occurs simultaneously on both sides. Typically, one side experiences more severe pain, and there is often a gap of many years between the onset of pain on one side and the development of pain on the other side.

The compression of vessels at the root entry zone (REZ) of the trigeminal nerve is the main cause of unilateral TN [19]. However, the etiology of BTN is complex and cannot be solely explained by the compression of vessels at the REZ of the trigeminal nerve. In 1926, Harris first reported the relationship between trigeminal neuralgia and multiple sclerosis . In a research article published by Harris in 1940, which studied 1,433 trigeminal neuralgia patients, 50 cases related to multiple sclerosis were reported, among which 7 patients (14%) exhibited bilateral symptoms [21]. Henderson reported that among 23 patients with MS experiencing TN, 7 patients had BTN [22]. Several authors have reported nearly identical results, indicating that MS plays a significant role in the development of BTN[23,24,25]. In this study, we did not assess whether TN was associated with MS. Therefore, further work is required to establish the relationship between MS and BTN.

There is currently no consensus on the treatment of BTN. Generally, drugs such as carbamazepine and gabapentin are preferred options for treatment[8,9]. When patient's drug treatment is ineffective or intolerable due to medication side effects, different surgical options can be considered. Radiofrequency ablation surgery can alleviate pain by selectively targeting different branches of the trigeminal nerve. Patient cooperation is crucial during the stimulation phase to ensure accurate positioning and localization of the radiofrequency lesion [13,25]. Therefore, preoperatively, patients must learn how to identify and specify where they feel facial stimulation. Due to the prolonged effect of anesthesia, patient cooperation may become more challenging during the surgical procedure. The precise placement of radiofrequency needles may induce anxiety and fear in some individuals, especially in awake patients. Additionally, there is a risk of irreversible damage to small and non-myelinated pain fibers, potentially increasing the occurrence of corneal inflammation [13]. Furthermore, there is a significant risk of postoperative bilateral trigeminal sensory and motor impairments. In a study by Bozkurt et al. [26] involving 89 patients with bilateral trigeminal neuralgia who underwent radiofrequency neurotomy, 54 patients received bilateral treatment, and within 6 months, 11 patients (12.3%) experienced early pain recurrence, while 17 patients (19%) encountered surgical complications, including diminished or lost corneal reflex, paralysis of chewing muscles, or facial numbness. Therefore, we do not recommend performing this procedure for patients with pain involving the first division of the trigeminal nerve. Gamma Knife radiosurgery, although minimally invasive, has a lower success rate and a higher recurrence rate compared to other surgeries, posing a significant risk of radiation-induced necrosis to the trigeminal nerve root entering the brainstem area in patients with BTN [17]. Therefore, for patients with BTN who have failed other surgical treatments, Gamma Knife radiosurgery should be considered as a salvage treatment option. MVD also offers effective treatment for BTN. Pollack et al. [7] reported that 35 patients with BTN underwent MVD, with 89% achieving excellent or good symptom control on the treated side, and 66% maintaining excellent or good symptom control on the operated side for up to 5 years post-surgery. In the study by Zhao et al. [9], which included 13 patients with BTN, 9 patients underwent consecutive bilateral MVD within a year, and the results demonstrated that 92.3% of the treated sides achieved favorable symptom control. In the long term, MVD is highly effective in alleviating pain, but this procedure involves the posterior cranial fossa, thereby carrying a higher risk of complications such as meningitis and mortality. In general,MVD is ineffective for TN associated with MS. This is because the underlying pathology involves demyelination of the trigeminal nerve root entry zone, rather than vascular compression of the trigeminal nerve. However, current research suggests that MS plays a significant role in the development of BTN. Therefore, MVD is not recommended for patients with BTN associated with MS.

PBC involves non-selectively compressing each branch of the trigeminal nerve at the trigeminal ganglion, typically performed under general anesthesia. This procedure does not require patient cooperation, alleviating anxiety and fear, thereby optimizing patient comfort. It selectively damages large to medium-sized myelinated fibers while preserving small fibers with corneal reflex[25].The immediate success rate of PBC for unilateral TN exceeds 98%[12], with a low 5-year recurrence rate of only 20%[13], and a low incidence of complications[14].However, there are currently no studies exploring the efficacy and safety of PBC surgery for BTN. The one-year, three-year, and five-year recurrence-free rates are 100%, 90.2%, and 80.2% respectively. All patients experiencing post-operative chewing muscle weakness recovered within 3 to 6 months. The majority of patients with post-operative facial numbness after PBC surgery regained sensation within 1 year. There were no occurrences of severe complications such as corneal inflammation, bilateral masseter paralysis leading to chewing, eating, and swallowing difficulties, or intolerable facial numbness. Additionally, three patients (three surgical sides) experienced recurrence postoperatively. They underwent a second percutaneous balloon compression procedure at our institution, all achieving excellent long-term results with no further recurrence. Upon discharge, all patients expressed satisfaction with the treatment outcomes. During long-term follow-up, as more patients experienced complications and relapses, the level of patient satisfaction declined, reaching 91.7% at the last follow-up. Therefore, our results establish PBC as a safe and effective method for treating BTN.

When performing PBC on patients with BTN, it is advisable to initially treat the side with more severe pain or longer duration of symptoms, while monitoring pain relief and potential surgical complications. In our study, a majority of patients with BTN experienced relief in pain on the non-operative side after undergoing unilateral PBC, and pain control using medication proved effective in achieving good management. If non-surgical side pain remains severe, we recommend monitoring pain relief and possible complications for more than 3 months before considering surgical intervention on the other side to prevent serious complications such as bilateral masseter muscle paralysis leading to difficulties in chewing, eating, swallowing, and unbearable facial numbness.

Despite achieving encouraging results in our study, there are still some limitations. Firstly, the follow-up duration was relatively short and varied, yet the median follow-up time for all patients exceeded 23 months, which can be cautiously accepted to assess treatment effectiveness. In addition, only 9 patients and 2 patient were followed up at 3 and 5 years post-treatment, making it difficult to draw conclusions about the long-term effectiveness of PBC. In the future, we will continue to follow up with BTN patients treated with PBC to report on the long-term outcomes of this treatment approach. Secondly, the relatively small number of cases in this study necessitates long-term, larger-scale, multicenter prospective research in the future to further validate our findings for this particular patient group.

To our knowledge, this is the first study evaluating the treatment outcomes of PBC for BTN. PBC emerges as an effective and relatively safe method for treating BTN, presenting a valuable pain management option in these rare cases of TN.

Funding No funding was received for conducting this study.
Conflicts of interest/Competing interests All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript.

Availability of data and material:The study is not applicable.

Ethics approval:All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Consent to participate: Due to the retrospective nature of this study, informed consent was not required.

Consent for publication: All authors agreed with the content and that all gave explicit consent to submit and that they obtained consent from the responsible authorities at the institute/organization where the work has been carried out, before the work is submitted.

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Table 1 Modifed Barrow Neurological Institute (BNI) pain scale

BNI scores	Defnitions
I	No pain, no medication
II	Occasional pain, not requiring medication
III a	No pain with medication
b	Controlled pain with medication
IV	Improved pain that is inadequately controlled by medication
V	Persistent pain that is inadequately controlled by medication

Table 2 Barrow Neurological Institute (BNI) facial numbness scale

BNI scores	Defnitions
I	no numbness
II	mild numbness
III	moderate numbness
IV	severe numbness

Table 3 Patient’s satisfaction scale—the Likert scale

Likert scale	Defnitions
1	Very unsatisfactory
2	Unsatisfactory
3	Neutral
4	Satisfactory
5	Very satisfactory

Table 4 Characteristics of cases with unilateral and bilateral TN

Features	Unilateral TN	Bilateral TN
Number of cases	867	37
Age(years)	66.0±10.4（20-97）	64.7±9.0（47-83）
F：M ratio	495:372（1.3:1）	28:9（3.1:1）
Symptom duration(years)	6.8±6.5（0.3-40）	9.0±8.0（0.2-40）
Familial TN	30(3.5%)	6（16.2%）
Associated diseases
hypertension	349(40.8%)	15（40.5%）
Other cranial nerve dysfunction	17(2.0%)	5（13.5%）

F, female; M, male; TN, trigeminal neuralgia;

Table 5 The clinical and surgical features of the 37 bilateral trigeminal neuralgia patients

Features	N (%)，Median (range)
Distribution of pain（74 sides）
1st	2（2.7%）
2nd	27（36.5%）
3rd	18（24.3%）
1st&2nd	5（6.8%）
2st&3rd	19（25.7%）
1st-3rd	3（4.1%）
Side affected initially（37 cases）
Right	18（48.6%）
Left	13（35.1%）
Simultaneous	6（16.2%）
Interval time Between two Sides(years）	7.8±7.4（0-30）
Time between treating the sides（months）（11cases）	21.4±12.6（3-50）
Follow-up time（48 sides)	23.7±15.6(2-62)
Postoperative complications（48 sides)
Facial numbness	46（95.8%）
Masserter muscle weakness	19（39.6%）
Corneal keratitis	1（2.1%）
Shingles	7（14.6%）

Table 6 Treatment efficacy of PBC procedure for patients with BTN

		Post-treatment
		Day 1 (n =48）	Month3 (n=47）	Month6 (n=39）	Year 1 (n =37)	Year 3 (n = 9)	Year 5 (n = 2）
BNI pain scale (n, %)	I	46（95.8%）	45（95.7%）	37（94.9%）	34（91.9%）	6（66.7%）	2（100%）
	II	1（2.1%）	1（2.1%）	1（2.6%）	1（2.7%）	1（11.1%）	0
	IIIa	1（2.1%）	1（2.1%）	1（2.6%）	1（2.7%）	1（11.1%）	0
	IIIb	0	0	0	1（2.7%）	1（11.1%）	0
	IV	0	0	0	0	0	0
	V	0	0	0	0	0	0
BNI facial numbness scale (n, %)	I	2（4.2%）	4（8.5%）	16（41.0%）	28（75.7%）	9（100%）	2（100%）
	II	40（83.3%）	38（80.9%）	20（51.3%）	8（21.6%）	0	0
	III	6（12.5%）	5（10.6%）	3（7.7%）	1（2.7%）	0	0
	IV	0	0	0	0	0	0
Masserter muscle weakness	Yes	19（39.6%）	5（10.6%）	0	0	0	0
Masserter muscle weakness	No	29（60.4%）	42（89.4%）	39（100%）	0	0	0

PBC,percutaneous balloon compression; BTN, bilateral trigeminal neuralgia; BNI, barrow neurological institute; f/u，follow-up

No competing interests reported.

Efficacy and safety of percutaneous balloon compression for bilateral trigeminal neuralgia： a retrospective study

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