Autonomic and histopathological effects of percutaneous trigeminal ganglion compression in the rabbit

Percutaneous balloon compression for trigeminal neuralgia: experience and surgical techniques from a single institution

OBJECTIVE

The treatment experience and the technical skill with percutaneous balloon compression (PBC) for treatment of primary trigeminal neuralgia (TN) were summarised in a single institution.

METHODS

This is a retrospective review including consecutive patients with typical symptoms of uni-lateral primary TN who underwent PBC from June 2020 to September 2021 in our institution. We excluded secondary aetiologies of TN. Patient demographics, surgical techniques and outcomes were reviewed. All included patients were initially managed with carbamazepine before PBC.

RESULTS

A total of 70 patients were included. The mean length of follow-up was 10.6 months. Sixty-nine (98.6%) were successfully treated, and only one patient failed due to particularly narrow foramen ovale. Amongst successfully treated patients, 68 (97.1%) had immediate pain relief, with one having delayed relief. Sixty-eight patients (97.1%) had immediate facial numbness post-operatively and one (1.4%) presented delayed numbness 7 days after surgery. In the last follow-up, regarding facial numbness, 22 (31.9%) patients had complete resolution, whilst 46 (67.6%) had different degrees of benefit. Forty-nine (71.0%) patients developed masseter muscle weakness with recovery at 3-month follow-up. No anaesthesia dolorosa, keratitis, intracranial infection or death occurred in this study.

CONCLUSION

PBC for treatment of TN has quick and effective result, and could be safely performed under general anaesthesia without discomfort to the patient. The common postoperative complications are facial numbness and masseter muscle weakness, with most being improved or recovered at follow-up.

Retrospective comparison of percutaneous balloon compression and radiofrequency-thermocoagulation in the management of trigeminal neuralgia

PURPOSE

To compare percutaneous balloon compression (PBC) and radiofrequency thermocoagulation (RFTC) for the treatment of trigeminal neuralgia.

METHODS

This was a retrospective single-center analysis of data from 230 patients with trigeminal neuralgia who underwent 202 PBC (46%) and 234 RFTC (54%) from 2002 to 2019. Comparison of demographic data and trigeminal neuralgia characteristics between procedures as well as assessment of 1) initial pain relief by an improved Barrow Neurological Institute (BNI) pain intensity scale of I-III; 2) recurrence-free survival of patients with a follow-up of at least 6 months by Kaplan-Meier analysis; 3) risk factors for failed initial pain relief and recurrence-free survival by regression analysis; and 4) complications and adverse events.

RESULTS

Initial pain relief was achieved in 353 (84.2%) procedures and showed no significant difference between PBC (83.7%) and RFTC (84.9%). Patients who suffered from multiple sclerosis (odds ratio 5.34) or had a higher preoperative BNI (odds ratio 2.01) showed a higher risk of not becoming pain free. Recurrence-free survival in 283 procedures was longer for PBC (44%) with 481 days compared to RFTC (56%) with 421 days (p=0.036) but without statistical significance. The only factors that showed a significant influence on longer recurrence-free survival rates were a postoperative BNI ≤ II (P=<0.0001) and a BNI facial numbness score ≥ 3 (p = 0.009). The complication rate of 22.2% as well as zero mortality showed no difference between the two procedures (p=0.162).

CONCLUSION

Both percutaneous interventions led to a comparable initial pain relief and recurrence-free survival with a low and comparable probability of complications. An individualized approach, considering the advantages and disadvantages of each intervention, should guide the decision-making process. Prospective comparative trials are urgently needed.

Blink reflex: A practical test to evaluate the trigeminal nerve injury following percutaneous balloon compression for the treatment of trigeminal neuralgia

OBJECTIVE

To evaluate the blink reflex (BR) in estimating the potential injury of trigeminal nerve following percutaneous balloon compression (PBC) surgery, and to determine the association between BR alterations and early surgical outcomes.

METHODS

In this single-center, prospective before-and-after study, a total of 74 patients who had primary trigeminal neuralgia and scheduled for PBC between October 2020 and June 2021 were prospectively included. BR testing and facial sensory assessment were performed pre- and post-PBC. The latency and the area under the curve (AUC) of pre- and postoperative R1 (R1_pre /R1_post ) and R2 (R2_pre /R2_post ) were measured.

RESULTS

The BR components were noticeably delayed or diminished following PBC. R1_post was elicited in only 26 patients, and absent in 48 patients. The residual R1_post had markedly reduced AUC (median difference [Hodges-Lehmann]: -59.5, 95% confidence interval [CI]: -217.5 to -6.9, p = 0.023). Compared with R2_pre , the latency of R2_post was considerably delayed (mean difference: 4.3, 95% CI: 2.9 to 5.7, p < 0.001) and the AUC was greatly suppressed (median difference [Hodges-Lehmann]: -388.4, 95% CI: -548.4 to -259.5, p < 0.001). After PBC, 58 patients had immediate total pain relief, and 16 had partial relief. The absence of R1_post was found in 46 of 58 (79.3%) patients with complete remission, whereas in only 2 of 16 (12.5%) patients with partial relief. Association analysis showed that the absence of R1_post was strongly associated with total pain relief (46/58 [79.3%] vs. 2/16 [12.5%], odds ratio [OR]: 26.8, 95% CI: 5.4 to 134.5, Cramér's V: 0.6, p < 0.001). The latency of R2_post in patients with total relief was significantly delayed (mean difference: 2.5, 95% CI: 0.3 to 4.6, p = 0.028). Patients experienced graded facial numbness after PBC, of whom 31 reported mild numbness (Grades I-II) and 43 reported more severe numbness (Grades III-IV). The absence of R1_post was significantly associated with facial numbness severity, 33/43 (76.7%) in Grades III-IV vs. 15/31 (48.4%) in Grades I-II (OR: 0.284, 95% CI: 0.105 to 0.771, Cramér's V: 0.3, p = 0.012). In patients with more severe numbness, the latency of R2_post was significantly delayed (mean difference: 2.7, 95% CI: 0.1 to 5.3, p = 0.043), and the reduction of AUC was much greater (median difference [Hodges-Lehmann]: 17.2, 95% CI: 0.5 to 35.4, p = 0.041).

CONCLUSION

Both R1 and R2 were significantly diminished after PBC and these alterations were associated with early surgical outcomes, suggesting that the BR is useful in evaluating trigeminal injury following PBC and could provide objective information about early prognosis.

Dissection of the Trigeminal Ganglion of Nonrodent Species Used in Toxicology Studies

The ganglion of the trigeminal (V cranial) nerve is generally sampled at necropsy in nonrodent toxicology studies only when somatic or autonomic peripheral nervous system toxicity is suspected. The ganglion is far more difficult to locate in nonrodents than in rats and mice, and suitable methods to dissect it have been described only for swine. The trigeminal nerve caudal to the ganglion passes through a canal, roofed by bone in dogs and rabbits and by a tough layer of dura mater in swine and nonhuman primates. The ganglion is partly or wholly obscured by overlying dura mater. Of the 3 intracranial branches of the nerve, the ophthalmic is delicate and the maxillary and mandibular have extremely short courses within the cranial cavity. Methods that are practical in routine toxicologic pathology for the dissection of the ganglion in nonrodent laboratory species are illustrated and relevant species differences in the anatomy of the intracranial part of the trigeminal nerve are highlighted.

An experimental animal model for percutaneous procedures used in trigeminal neuralgia

OBJECT

This study describes an experimental rabbit model that allows the reproduction of percutaneous operations that are used in patients with trigeminal neuralgia (TN). Attention was given to an exact anatomical description of the rabbit's middle cranial fossa as well as the establishment of conditions for a successful procedure.

METHODS

Morphometric measurements were taken from 20 rabbit skulls and CT scans. The anatomy of the trigeminal nerve, as well as its surrounding structures, was assessed by bilateral dissection of 13 New Zealand white rabbits (NWR). An ideal approach of placing a needle through the foramen ovale to reach the TG was sought. Validation of correct placement was realized by fluoroscopy and confirmed by dissection.

RESULTS

Precise instructions for successful reproduction of percutaneous procedures in NWR were described. According to morphological measurements, for balloon compression of the trigeminal ganglion (TG) the maximal diameter of an introducing cannula is 1.85 mm. The diameter of an empty balloon catheter should not exceed 1.19 mm, and the length of the inflatable part of the balloon can range up to 4 mm. For thermocoagulation the needle electrodes must not exceed an external diameter of 1.39, mm and the length of the non-insolated tip can range up to 4 mm. Glycerol rhizolysis can be achieved because the trigeminal cistern in the NWR is a closed space that allows a long dwelling time (>10 min) of the contrast agent.

CONCLUSIONS

An experimental NWR model intended for the reproduction of percutaneous procedures on the TG has been meticulously described. This provides a tool that enables further standardized animal research in the field of surgical treatment of TN.

A review of percutaneous treatments for trigeminal neuralgia

BACKGROUND

Common treatments for trigeminal neuralgia include percutaneous techniques, microvascular decompression, and Gamma Knife radiosurgery. Although microvascular decompression is considered the gold standard for treatment, percutaneous techniques remain an effective option for select patients.

OBJECTIVE

To review the historical development, advantages, and limitations of the most common percutaneous procedures for trigeminal neuralgia: balloon compression (BC), glycerol rhizotomy (GR), and radiofrequency thermocoagulation (RF).

METHODS

Publications reporting clinical outcomes after BC, GR, and RF were reviewed and included. Operative technique was based on the experience of the primary surgeon and senior author.

RESULTS

All 3 percutaneous techniques (BC, GR, and RF) provide effective pain relief but differ in method and specificity of nerve injury. BC selectively injures larger pain fibers while sparing small fibers and does not require an awake, cooperative patient. Pain control rates up to 91% at 6 months and 66% at 3 years have been reported. RF allows somatotopic nerve mapping and selective division lesioning and provides pain relief in up to 97% of patients initially and 58% at 5 years. Multiple treatments improve outcomes but carry significant morbidity risk. GR offers similar pain-free outcomes of 90% at 6 months and 54% at 3 years but with higher complication rates (25% vs. 16%) compared with BC. Advantages of percutaneous techniques include shorter procedure duration, minimal anesthesia risk, and in the case of GR and RF, immediate patient feedback.

CONCLUSION

Percutaneous treatments for trigeminal neuralgia remain safe, simple, and effective for achieving good pain control while minimizing procedural risk.

The predictive power of balloon shape and change of sensory functions on outcome of percutaneous balloon compression for trigeminal neuralgia

OBJECT

Percutaneous balloon compression is a simple and effective treatment of trigeminal neuralgia. However, results between and within different series are varying. To further improve the results in terms of pain relief, the authors believe that a careful study of the surgical procedure is important. The object of this study was to analyze the impact of balloon shape, balloon position, balloon volume, and compression time on duration of the therapeutic effect following percutaneous balloon compression. Furthermore, they analyzed the sensory side effects associated with this treatment, and how these relate to surgical parameters.

METHODS

Medical records and intraoperative radiographs from 87 balloon compressions were reviewed, and different surgical parameters were categorized. Univariate and multivariate analyses were performed to correlate surgical parameters to pain relief. Sensory testing with a transcutaneous electrical stimulation technique and clinical examination data were reviewed to analyze changes in sensory function.

RESULTS

The balloon shape had a significant impact on time to recurrence of pain. A pear-shaped balloon resulted in a far better surgical result than a non-pear-shaped balloon (p < 0.001). The difference between a distinct and a less distinct pear shape was not significant (p = 0.14). Statistical significance was not reached for any of the other parameters in relation to duration of therapeutic effect. A pear-shaped balloon was also significantly associated with increased thresholds for percutaneous electrical stimulation in the immediate postoperative period, but the perception thresholds were normalized at the late follow-up at 3-9 months. A similar outcome was found for clinical testing with light touch and pinprick.

CONCLUSIONS

The authors have demonstrated that using a pear-shaped balloon when performing percutaneous balloon compression for trigeminal neuralgia results in longer pain relief than non-pear-shaped balloons. Other surgical parameters seemed less important with respect to pain relief. Balloon compression also, in many cases, results in hypesthesia.

Cardiovascular response during trigeminal ganglion compression for trigeminal neuralgia according to the use of local anesthetics

OBJECTIVES

There are controversies about the use of local anesthetics during balloon compression for trigeminal neuralgia (TN) as a protective factor for cardiovascular events. The objective of this study was to investigate cardiovascular parameters (blood pressure and heart rate [HR]) of patients that underwent trigeminal balloon compression with local anesthetics compared to a control group (placebo).

METHODS

This is a randomized controlled study; 55 patients were randomized into two groups: study (deep sedation and trigeminal block with 0.8-mL lidocaine 2%) and control group (deep sedation and trigeminal injection of 0.8-mL saline). Blood pressure and HR were measured in five distinct moments: preoperative, during puncture for local anesthesia/placebo, during puncture with the catheter, during balloon compression, and final evaluation. Statistical analysis was performed with Pearson's chi (2) and McNemar tests and the analysis of variance for repetitive measures.

RESULTS

The means of systolic and diastolic blood pressures (SBP and DBP, respectively) were higher in the control group when compared to the study group at the evaluation during puncture with the catheter (p < 0.001) and balloon compression (p < 0.001 and p = 0.018 for DBP and SBP, respectively). There was an increase in the HR in the control group during the procedure (p = 0.017).

CONCLUSION

The use of local anesthetics during the trigeminal balloon compression for TN can have a preventive role for the risk of cardiovascular events.

Perioperative and long-term operative outcomes after surgery for trigeminal neuralgia: microvascular decompression vs percutaneous balloon ablation

Objectives

Numerous medical and surgical therapies have been utilized to treat the symptoms of trigeminal neuralgia (TN). This retrospective study compares patients undergoing either microvascular decompression or balloon ablation of the trigeminal ganglion and determines which produces the best long-term outcomes.

Methods

A 10-year retrospective chart review was performed on patients who underwent microvascular decompression (MVD) or percutaneous balloon ablation (BA) surgery for TN. Demographic data, intraoperative variables, length of hospitalization and symptom improvement were assessed along with complications and recurrences of symptoms after surgery. Appropriate statistical comparisons were utilized to assess differences between the two surgical techniques.

Results

MVD patients were younger but were otherwise similar to BA patients. Intraoperatively, twice as many BA patients developed bradycardia compared to MVD patients. 75% of BA patients with bradycardia had an improvement of symptoms. Hospital stay was shorter in BA patients but overall improvement of symptoms was better with MVD. Postoperative complication rates were similar (21% vs 26%) between the BA and MVD groups.

Discussion

MVD produced better overall outcomes compared to BA and may be the procedure of choice for surgery to treat TN.

Trigemino-cardiac reflex during transsphenoidal surgery for pituitary adenomas

BACKGROUND

The trigemino-cardiac reflex (TCR) is a well-recognized phenomenon consisting of bradycardia, arterial hypotension, apnea, and gastric hypermotility. It occurs during ocular surgery or other manipulations around the orbit and can also be elicited by stimulation of the central part of the trigeminal nerve during surgery for processes of the cerebellopontine angle. The present retrospective study was conducted to determine if TCR occurs during transsphenoidal surgery in the same way.

METHODS

TCR was defined as a drop in mean arterial blood pressure (MABP) and the heart rate (HR) of more than 20% to the baseline values before the stimulus and coinciding with manipulation of the trigeminal nerve. Pre-, intra-, and postoperative HR and MABP were retrospectively reviewed in 117 patients who underwent resection of pituitary adenomas near the trigeminal nerve at the cavernous sinus in the supine position. Tumor invasiveness was classified according to the modified Hardy criteria.

RESULTS

Of the 117 patients with immunohistochemically and/or electromicroscopically proven pituitary adenoma, 12 (10%) patients demonstrated intraoperative evidence of TCR according to the strict inclusion criteria. In these 12 patients, the HR and MABP decreased by a mean of 43 and 54%, respectively, from the preoperative mean levels during microsurgical manipulation near the cavernous sinus and returned to physiological levels within 10 min after cessation of this surgical maneuver. The percentage of invasive adenomas (grade III-IV) was significantly higher in the TCR subgroup than in the non-TCR subgroup (83% versus 22%).

CONCLUSION

The present results give evidence for the first time that TCR may occur during transsphenoidal surgery in the supine position for resection of pituitary adenomas near the cavernous sinus, leading to a significant decrease in HR and MABP under a standardized anesthetic protocol.

Trochlear Nerve Palsy after Repeated Percutaneous Balloon Compression for Recurrent Trigeminal Neuralgia: Case Report and Pathogenic Considerations

OBJECTIVE AND IMPORTANCE

Repeated percutaneous balloon compression for the treatment of idiopathic trigeminal neuralgia is infrequent. When a second procedure is performed, the outcome is unknown. A patient developed an isolated trochlear nerve palsy after undergoing percutaneous trigeminal ganglion balloon compression for a second time. The mechanism of diplopia and the complications associated with this technique were studied.

CLINICAL PRESENTATION

The patient was a 67-year-old woman with a history of medically refractory idiopathic trigeminal neuralgia involving all three divisions of the right trigeminal nerve.

INTERVENTION

Percutaneous balloon compression was performed. Despite initial total relief from pain without complications, the patient again displayed manifestations of trigeminal neuralgia 3 months after the procedure. The pain disappeared after she underwent a second balloon compression procedure, but she developed an isolated trochlear nerve palsy, which spontaneously resolved in 2 months.

CONCLUSION

Isolated trochlear nerve palsy is a rare and reversible complication after percutaneous balloon compression for trigeminal neuralgia. This case illustrates that the mechanism of injury to the fourth nerve is the result of an erroneous technique: excessive penetration of the Fogarty catheter in Meckel's cave beyond the porus trigemini and compression of the cisternal segment of the trochlear nerve when the inflated balloon is pushed against the tentorium.

Autonomic nervous system and neuroendocrine changes in patients with idiopathic trigeminal neuralgia

To investigate sympathetic nervous system and neuroendocrine changes in idiopathic trigeminal neuralgia, we determined the plasma level of the catecholamines norepinephrine and epinephrine, as well as cortisol and ACTH in 16 patients (55.3 +/- 8.3 years) with trigeminal neuralgia at four different times during the day (7.00, 13.00, 17.00 and 23.00). Morning and evening values of plasma norepinephrine as well as the daily mean value (dmv) were significantly higher (p < 0.01) in patients with trigeminal neuralgia than in an age- and gender-matched control group. Moreover, morning, afternoon and dmv epinephrine values were also significantly elevated. The dmv norepinephrine levels correlated with the intensity of the attacks (r = 0.68, p < 0.01), the frequency of the attacks (r = 0.75, p < 0.01) and the duration of the disease (r = 0.78, p < 0.01). In addition to elevated catecholamines, trigeminal neuralgia patients also demonstrated significantly increased morning, evening and daily mean values of plasma cortisol. Thus, patients with trigeminal pain have an increased sympathetic nervous system activity for an extended period of time without a direct link to pain attacks, which suggests that the sympathetic nervous system itself is at least co-activated in trigeminal neuralgia and perhaps plays a role in the induction and maintenance of trigeminal pain. The neuroendocrine changes are similar to cluster headache and point to a central dysregulation of the hypothalamic-pituitary-adrenal axis, possibly due to the cyclic phenomena in idiopathic trigeminal neuralgia.

Axon and ganglion cell injury in rabbits after percutaneous trigeminal balloon compression

New Zealand white rabbits were used to determine whether the changes in the Vth cranial nerve sensory root after compression were associated with the loss of a specific subclass of Vth cranial nerve ganglion cells, the disappearance of a distinct subset of primary afferent terminals in Vth cranial nerve nucleus caudalis, and/or injury to a specific axonal fiber type. There was no significant difference in the size of surviving ganglion cells after Vth cranial nerve compression, as measured 2 to 3 months after injury (P > 0.5, n = 4). Densitometric analysis of the nerves of rabbits that survived > 2 months after compression showed no significant difference in the immunoreactivity of substance P and calcitonin gene-reactive protein between compressed and control sides (P > 0.1, n = 4). Fink-Heimer staining of the Vth cranial nerve subnucleus caudalis revealed that transganglionic degeneration was most dense in the deeper layers, which are the sites of termination of large myelinated fibers. Ultrastructural evaluation of the type of myelinated axons injured by Vth cranial nerve compression in rabbits killed 7, 14, 37, and 270 days after injury was studied, and morphometric analysis was performed. The frequency distribution of axon diameters was significantly different for injured and control areas. The injured areas had higher ratios of small (< 3-microns diameter) to large-diameter axons compared to control distribution. These data indicate that balloon compression results in loss of fibers from the Vth cranial nerve sensory root and extensive transganglionic degeneration in the Vth cranial nerve brain stem complex. Cell size measurements and immunocytochemical data suggest that there is no specific loss of small ganglion cells or fine-caliber primary afferents. These experiments suggest that balloon compression relieves trigeminal pain by injuring the myelinated axons involved in the sensory trigger to the pain.

Macroscopic effects of percutaneous trigeminal ganglion compression (Mullan's technique): an anatomic study

After the use of Mullan's technique, macroscopic changes take place on the gasserian ganglion and the surrounding structures. These changes were studied on 20 trigeminal nerves of 10 fresh adult cadavers. Changes took place on the dura as well as in the neural elements. There was compression on the ganglion and on the trigeminal nerve, and there were changes in the position of the trigeminal root, with shortening of its cisternal segment. When the balloon was inflated to capacity (0.75-1.0 ml), dural stretching in an area of 15 x 10 mm took place. This stretching of the dura extended from the lateral wall of the cavernous sinus to the level of the porus trigemini. Despite these important mechanical effects, we never found a rupture or tear on the dura or the trigeminal nerve fibers. We discuss the relationship between mechanical effects and clinical results.

Changes in systemic blood pressure and cardiac rhythm induced by therapeutic compression of the trigeminal ganglion

Percutaneous compression of the trigeminal ganglion, which is currently being used for the control of trigeminal neuralgia, induces marked intraoperative elevations of the systemic blood pressure and heart rate changes, which may increase the risk of cardiovascular complications. We have analyzed the characteristics of the arterial hypertensive response and the cardiac rhythm changes induced by percutaneous compression of the trigeminal ganglion in 42 consecutive, unselected patients undergoing operations for essential trigeminal neuralgia under three different regimens of anesthesia. The first 22 patients (Group 1) underwent operations under brief general anesthesia without endotracheal intubation. The following 10 patients (Group 2) had general anesthesia with intubation and mechanical ventilation and received larger doses of hypnotic and analgesic agents. Finally, 10 more patients (Group 3), who had general anesthesia with intubation, underwent local anesthetic blockade of Meckel's cave (injection of 1 ml of 1% lidocaine) before ganglion compression. Foramen ovale puncture elicited bradycardia in the majority of the patients of Groups 2 and 3, but only four patients (18%) of Group 1 showed bradycardia. Ganglion compression caused marked tachycardia in all patients of Groups 1 and 2; about one-third of the patients also had extrasystoles. By contrast, patients of Group 3, who had local anesthetic blockade of Meckel's cave before ganglion compression, did not develop tachycardia or extrasystoles. Foramen ovale puncture elicited marked elevations of the systemic blood pressure in all patients. Ganglion compression further increased blood pressure, except in patients of Group 3, who had local anesthetic blockade of Meckel's cave.(ABSTRACT TRUNCATED AT 250 WORDS)

Distribution patterns of sensory innervation from the trigeminal ganglion to cerebral arteries in rabbits studied by wheat germ agglutinin-conjugated horseradish peroxidase anterograde tracing

Distribution patterns of sensory nerves from the trigeminal ganglion to cerebral arteries in rabbits were studied by the wheat germ agglutinin-conjugated horseradish peroxidase anterograde tracing technique along with the 3,3',5,5'-teramethylbenzidine method. Labeled sensory nerves were densely distributed in whole-mount specimens of cerebral arteries after the injection of wheat germ agglutinin-conjugated horseradish peroxidase into the trigeminal ganglion. The characteristics of the innervation in rabbits included: 1) cerebrovascular sensory nerves were more dense in the ipsilateral side than in the contralateral side; 2) the anterior cerebral artery was less densely innervated than the posterior cerebral artery; 3) labeled nerves on the proximal segment of arteries were more prominent than those on the distal segment. The smallest pial branches of the middle cerebral, posterior cerebral, and anterior inferior cerebellar arteries overlying the fine sensory nerves were 50, 75, and 80 microns in diameter, respectively. Two patterns of the sensory innervation were seen. A meshwork pattern was mainly observed in the circle of Willis and the proximal segments of its main branches, as well as in the upper two thirds of the basilar artery; a parallel or slightly twisted pattern was shown in the small pial arterioles. Our results in this study may be useful to understand better the trigeminocerebrovascular system.

Percutaneous trigeminal nerve compression for treatment of trigeminal neuralgia: results in 50 patients

The purpose of this study was to review the results of the treatment of trigeminal neuralgia by percutaneous trigeminal nerve compression in 50 patients during a period of 7.5 years and to review the factors associated with pain recurrence. Mean patient age was 61 years (range, 35-86). Among the patients, 52% had previous destructive peripheral procedures; 24% had first division pain; and 10% had multiple sclerosis. The mean follow-up was 3 years (range, 9 mo to 7.5 yr). Eighty-six percent of the patients were satisfied or very satisfied with their pain relief. Mild numbness persisted in 74%, and one patient thought it was severe. Minor masseter weakness resolved in all patients in a maximum of 1 year. Aseptic meningitis occurred in 3 patients. Minor dysesthesia was seen in 20%. Transient 6th nerve palsy was present in one patient. Anesthesia dolorosa or absence of the corneal reflex did not happen. The recurrence rate was 26% (13/50). The mean time until recurrence was 1.5 years (range, 14 d to 3.5 yr). Sixty-two percent (8/13) of patients with recurrence required a subsequent compression. When another compression was done, four of eight had recurrent pain once again. Three of these four patients had undergone two to eight previous destructive procedures. Overall, 8 of 13 patients with recurrence had undergone previous destructive procedures. Early recurrence (in < 1 week) or failure to relieve pain occurred in 8% (4/50) of patients. Half of those with early failure had a subsequent compression. After compression, 70% of patients with recurrence did have numbness.(ABSTRACT TRUNCATED AT 250 WORDS)