Trigeminal nerve block with alcohol is an accepted treatment for trigeminal neuralgia (TN),1,2 but is not as widely used as other percutaneous procedures or microvascular decompression.3 – 12 The main reason for this reluctance to perform an alcohol block of the trigeminal nerve for the management of TN is the concern that it provides limited pain relief and that repeated blocks have a lower success rate and a higher morbidity rate including neuritis.13 However, this concern has not been well validated1,14,15; therefore, we evaluated the efficacy and related complications of an alcohol block of the mandibular division (V3) of the trigeminal nerve for the treatment of TN. We also examined whether a previous alcohol block affected procedure outcomes.
All patients that received a V3 alcohol block for TN between March 2000 and February 2007 were allocated for the study. This prospective study was approved by the IRB at Ajou University Hospital in Korea. Three hundred fifty-two patients were diagnosed with TN, and of these, 142 patients had pain in the V3 division. Ninety-eight patients with V3 TN participated in the study and informed consents were obtained (Fig. 1).
All 98 patients fulfilled the diagnostic criteria for TN as detailed in the international classification of headache disorders.16 Magnetic resonance imaging was performed to exclude tumors and other brain lesions, such as those caused by multiple sclerosis. All study patients had previously been treated with carbamazepine and/or other anticonvulsants to which they had become immune or could not tolerate the side effects of the drugs (Table 1).
The V3 block was performed with fluoroscopic guidance. One milliliter 1% lidocaine was used for skin anesthesia. An 8-cm, 21-gauge needle (Hakko Medical, Nagano-Ken, Japan) was introduced below the zygomatic arch 1.5 to 2 cm anterior to the tragus and directed medially across the infratemporal fossa until it impinged on the lateral pterygoid plate, and was then “walked off” posteriorly until it passed just posterior to the lateral pterygoid plate in the anteroposterior oblique view (Fig. 2, A and B). At this point, needle placement was confirmed to be in proper position per the submentomandibular view (Fig. 2, C and D), and then 0.7 mL 1% lidocaine was injected. After obtaining a sensory loss in the V3 distribution area, 0.7 mL absolute alcohol (Dehydrated Alcohol Injection, USP; Tera Pharmaceuticals, Buena Park, CA) was administered.
Success was defined as the achievement of a pain-free state without medication. Recurrence was defined as the return of any pain, regardless of whether it was controlled by medication or required another procedure. Patients were contacted for periodic follow-up examinations bimonthly by one of our residents who was not otherwise involved in this study. The total follow-up duration was 44.1 ± 24.0 months (range, 2–86 months).
Kaplan-Meier analysis was used to construct pain-free survival curves for censored survival data, and the log-rank test was used to compare the survival curves. The relationships between independent preoperative variables and treatment outcomes were determined by Cox multivariate proportional hazards analysis. Statistical significance was accepted for P values of <0.05.
Ninety-eight patients received 160 V3 blocks during the study period. The clinical characteristics of the study subjects are summarized in Table 1. Seven of the 98 patients (7.1%) died of unrelated causes during the follow-up period, and 21 (21%) were lost to follow-up. Thirty-five of the study subjects (36%) had no further treatment after the first alcohol V3 block over the study period. However, 45 patients (45.9%) experienced recurring pain after the first block and 2 subjects chose medication for pain control when pain recurred (Fig. 1).
Ninety-seven of the 98 study subjects (99%) experienced complete and immediate pain relief without any medication after the first block. According to Kaplan-Meier analysis conducted at 7 years after the first study procedure, mean and median pain-free durations were 46 and 39 months, respectively. The probabilities of remaining pain free at 1, 2, 3, and 7 years after a successful alcohol block were 90.4%, 69%, 53.5%, and 33%, respectively. No significant difference in pain-free durations was found between patients with and without previous alcohol blocks (Fig. 3). Mean (median ± SE, 95% confidence interval) pain-free durations for first and repeated blocks were 47 months (41.0 ± 5.8 months, 30.0–52.4) and 41 months (29.0 ± 10.7 months, 8.1–50.0), respectively.
Thirty-two (20%) of the 160 blocks were associated with complications. Eighteen patients (11.3%) complained of paresthesia, dysesthesia, or deep sensory loss, although all study patients had varying degrees of sensory deficit on the V3 area. However, all sensory discomforts gradually decreased, patients adapted without medication, and the majority of complications resolved within 6 months. Other complications included 7 cases of masseter muscle weakness, 3 of heavy salivation, 3 of tinnitus, and 1 hematoma in the upper cheek. No significant difference in the incidence of complications was found between patients with and without previous alcohol blocks (P < 0.076).
Patient age, gender, onset duration, lateralization of the lesion, and history of surgical procedures were not found to be related to the procedure outcome. However, patients with a complication achieved a significantly longer pain-free duration than patients without a complication (Fig. 4).
Pain relief duration observed in this study is comparable with that reported for alternative techniques such as radiofrequency thermocoagulation; rates of complete pain relief at 1, 2, and 5 years after the procedure were 70%–90%, 62%–65%, and 51%–56%, respectively.3,4 This study failed to find a significant degradation in pain relief duration between first and repeat blocks. This is consistent with a previous study that observed continued efficacy of repeated trigeminal nerve alcohol blocks, even after 14 blocks had been administered in 1 individual over several years.15,17 Our patients with complications had a significantly longer pain-free duration (60 months) than patients without complications (41 months), which is similar to earlier studies.18 – 20 However, complications of V3 alcohol block were not as serious as other authors have reported.15,21
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