Is peripheral alcohol injection of value in the treatment of trigeminal neuralgia? An analysis of 100 cases

Abstract

This retrospective study assessed the effectiveness and complications of peripheral alcohol injections in the management of trigeminal neuralgia (TN). 100 patients were analyzed who received 250 peripheral alcohol injections from June 2004 to January 2010. The duration of effect of alcohol blocks, the effect of repeated administration, and complications associated with alcohol injections were examined. The distal injection technique was applied. The branch of the nerve was identified and confirmed. After carefully anesthetizing the nerve with local anesthesia, 1–1.5 ml of absolute alcohol was injected depending on the nerve involved. Pain relief lasted for a mean of 14.13 ± 8.66 months. There was a fall in the duration of effect with subsequent injections. No serious complications were reported. Only 3% patients presented with non-neuralgic pain, swelling, burning sensation, trismus, dysesthesia, soreness, infection and the expected loss of sensation along the branch involved in TN. The combination of efficacy and reduced morbidity makes this procedure preferable for the treatment of TN. Alcohol injections are useful in those who are refractory to drug therapy, the elderly, medically compromised patients, unwilling to undergo neurosurgical procedures and in whom surgery is delayed for any reason.

Trigeminal neuralgia (TN) or tic douloureux, is a syndrome characterized by sudden, usually unilateral, severe, brief, stabbing, lancinating, recurring pain in the distribution of one or more branches of the fifth cranial nerve. It usually begins as a relapsing disease with pain-free intervals that may last months or years. These intervals typically grow shorter and eventually disappear. As the disease progresses, patients can have difficulty in talking, eating, and maintaining oral hygiene out of fear of triggering the pain. In severe cases, TN may significantly decrease the quality of life with marked depression and anxiety.

Despite recent advances in treatment, TN remains an incapacitating condition, which is difficult to treat successfully in every patient. At present it is standard practice to use carbamazepine as first line treatment, sometimes with the later addition of oxycarbazepine, phenytoin, baclofen, lamotrigine, gabapentine or sodium velproate . The relief provided by carbamazepine or other drugs may decrease over time, and side effects may necessitate discontinuation of the medication. About half of all patients eventually require an operation for pain relief . T aylor et al. reported a 16 year follow up on 143 patients treated with carbamazepine and found it to be effective in 99 patients (69%), but 19 of those patients later became resistant to the drug and required a variety of surgical procedures.

Operative treatments in current use include: neurectomy of trigeminal nerve branches outside the skull; percutaneous ablation that creates trigeminal nerve or trigeminal-ganglion lesions with heat (radiofrequency thermal rhizotomy) ; injection of glycerol into the trigeminal cistern (retrogasserian glycerol rhizotomy ); physical compression (trigeminal-ganglion balloon microcompression ); gamma knife surgery . Microvascular decompression (MVD) is intended to alleviate TN by relieving compression of the nerve at some point along its course . MVD is a safe and effective treatment for TN, with a high rate of long-term success, which makes it an attractive treatment for eligible patients with medically intractable tic .

The management of TN has also involved peripheral injections of different chemical agents into the affected nerve. The first substance used was chloroform. Later, boiling water, glycerol, phenol, high concentrations of tetracaine , and streptomycine were also used. Peripheral alcohol injections have also been used, preferably during the first attack, or if the patient is very old . Patients with serious medical morbidity who cannot undergo invasive surgical procedures safely may benefit from injection of alcohol into the painful peripheral trigeminal nerve branch . This technique is associated with pain relief for 6–16 months .

The neuralgic pain is so severe that it has led to suicide attempts in some patients. This condition requires early diagnosis and immediate management. Most patients with this disease are old, infirm and not good candidates for surgery so there is a need for a relatively simple, minimally invasive procedure that immediately controls the pain. A survey of the initial and long term results of operations and alcohol injections in 650 patients revealed the marked contrast between the lives of patients who are permanently cured and those who continue to suffer recurring pain .

The purpose of this study is to assess the efficacy of peripheral alcohol injection, a minimally invasive procedure that has minimal, or no side effects in the treatment of TN. The procedure can be repeated without any additional risk.

Materials and methods

100 consecutive patients treated with 250 alcohol injections were identified. The study was conducted at a tertiary care hospital from June 2004 to January 2010. The age and gender of the patients was determined at the first visit.

The diagnosis was based on a detailed history and clinical examination. Orthopantograph (OPG), computed tomography (CT) scanning or magnetic resonance imaging (MRI) was performed for every patient to exclude any local pathology or lesion at brain level. No secondary pathology was seen. No history of trauma or direct nerve injury was observed. All patients were found to have idiopathic TN. According to the division of the trigeminal nerve involved, TN was divided into maxillary and mandibular types. There were no cases of TN involving the ophthalmic division of trigeminal nerve.

Different physicians had treated most of the patients medically before this presentation. The patients had not kept records of their previous medication so this and any adverse effects cannot be reported here. Some patients gave a vague history of using maximum doses of drugs such as baclofen, lamotrigine, and gabapentine. Discussion with the patients revealed that most had used maximum doses of carbamazepine (up to 1200 mg daily in divided doses) but had now become refractory to drugs. Since the patients had been treated medically previously, alcohol injection could not be reported as the first choice of treatment for these patients.

All the patients gave written informed consent for alcohol injection treatment. They gave informed consent willingly because they were in acute pain and wanted to alleviate the pain.

Injection technique

On the first visit, the branch of the nerve involved was identified according to the site of the pain and confirmed using a diagnostic local anesthetic injection of 2% lignocaine with adrenaline 1:200,000 at the site, repeated three times on consecutive days. Early morning appointments were given to the patients.

For the alcohol injection, 1–1.5 ml of absolute alcohol was used in a syringe with a 25/27 Gauge needle (short or long depending on the anatomical site). The amount of alcohol injected was determined according to the nerve involved. The protocol was 1 ml each for long buccal and mental nerves; 1.5 ml each for infra-orbital and inferior alveolar nerves. Since the injection of absolute alcohol is painful, the nerve was anesthetized using 2% lignocaine with adrenaline before treatment. Apart from pain relief, the point of entry of the local anesthetic injection provided a guideline for the exact and effective injection of absolute alcohol because of anatomical variation. After the nerve had been anaesthetized, absolute alcohol was injected into the confirmed branch of the trigeminal nerve according to the technique described below.

For infra-orbital nerve injection in the maxillary division an extra-oral approach was used. The infra-orbital foramen was localized using the index finger of the left hand placed at the infra-orbital rim and slid down to rest in a depression that contain foramen, almost 5–7 mm below the rim at the junction of the medial one-third and lateral two-thirds of the infra-orbital rim. The index finger was kept there and absolute alcohol was injected.

For mental nerve injection in the mandibular division an extra-oral approach was preferred over an intra-oral vertical approach. A point for injection was marked extra-orally in the middle of the mandible (between the occlusal plane of the mandibular teeth and the lower border of the mandible) extra-orally below the second premolar. The mental foramen had been identified in an OPG in relation to the apices of the first and second premolars.

For inferior alveolar nerve injection in the mandibular division a traditional technique was used. The thumb of the non-injecting hand was placed in the deepest portion of the concavity of the ramus between the internal and external ridges of the mandible. The other four fingers were placed extra-orally on the posterior border of the ramus. With the barrel of the syringe lying over the premolars of the opposite side, the 25 G long needle was directed parallel to the occlusal plane of the mandibular teeth, bisecting the thumb, and was aimed at the midpoint of the ramus located between the thumb and the extra-orally placed fingers. The needle was advanced through the pterygomandibular raphe into the pterygomandibular space, 1.5 cm deep from the mucosa.

For the long buccal nerve an intra-oral approach was used. Solution was deposited in the mucous membrane in the vicinity of the anterior border of the ramus of the mandible, distal and buccal to the most distal molar tooth in the arch. A 25/27 G long needle was preferred because of the posterior deposition site, not the depth of tissue insertion (which is minimal).

The techniques for lingual nerve, supra-orbital and supra-trochlear nerves were not applied because none of these nerves were involved in the patients with TN.

The patients were treated in an out-patient setting with no systemic sedation or analgesia, and all tolerated the procedure extremely well except for three patients who were uncooperative. They were discharged home immediately following the injection. The follow-up period ranged from 1 day to 5 years. The patients were advised to report back immediately if the pain recurred. They were also checked by regular follow-up at intervals of 1 day, 1 week, 1 month, 2 months, 3 months, 6 months, 12 months, and then every year up to 5 years.

Outcome measures

The effectiveness of alcohol injection and the effect of repeated injections were noted. An injection was considered effective if pain relief was obtained for at least 2 months. The criterion of successful injection was total relief of pain. The magnitude of pain and detailed pain assessments, such as visual analogue scales, were not considered in this study. The relapse time was measured as the number of months. The complications of alcohol injections were identified.

Statistical analysis

The collected data were analyzed using SPSS Version 16. The association between alcohol injections and efficacy in different branches of the trigeminal nerve was tested using a χ 2 test. One-way ANOVA was applied to check the significance of mean duration of effect of alcohol injection in different branches. The least significant difference (LSD) test was used to compare the significant difference between the pair of means at a 5% level of probability.

Results

Of 113 patients with TN, the study sample size was reduced to 100 patients. 13 patients were excluded from the study because they did not report back for proper follow-up. The 100 patients studied received a total of 250 injections with a mean of 2.5 injections (range 1–5) per patients. The mean age of the patient was 47 ± 10 years (range 24–70 years). There were 60 men and 40 women; a ratio of 3:2.

The overall success rate for the procedure was 86% ( n = 216) on the stated criteria and 34 injections (14%) were ineffective. Of the successful injections, the mean duration of action was 14.13 ± 8.66 months (range 2–56 months).

The degree of pain relief in ineffective injections remained from 1 week to less than 2 months. Probable reasons were anatomical variations in the nerve, the uncooperative behavior of the patients and faulty technique.

In the maxillary division, in cases where the infra-orbital nerve was involved, 74 alcohol blocks were used in 32 patients. In the mandibular division, the inferior alveolar nerve was most commonly blocked ( n = 135) and the long buccal nerve accounted for 20 injections. The inferior alveolar injections were successful in 90% with an average duration of effect of 22.51 ± 8.55 months. The successful injections (65%) of the long buccal nerve were effective for an average of 7.62 ± 7.93 months ( Table 1 ).

Table 1
Effectiveness and duration of alcohol injection.
Description of injection TN in maxillary division TN in mandibular division
Infra-orbital Inferior alveolar Mental Long buccal
Total number of injections n = 250 (in 100 patients) 74 (32) 132 (40) 24 (13) 20 (15)
Ineffective injections ( n = 34) 12 10 5 7
Effective injections ( n = 216) 62 (88.6%) 122 (90.4%) 19 (76%) 13 (65%)
Duration of effect, months mean ± SD 16.27 ± 9.27 c
(03–48)
22.51 ± 8.55 d
(5–56)
10.11 ± 8.90 ab
(03–41)
7.62 ± 7.93 a
(2–32)
χ 2 = 13.3714 and its P -value is 0.0039 at 5% level of probability. The mean ± SD followed by different letters are significantly different at P < 0.05. Infra-orbital and inferior alveolar are assigned c and d, respectively, indicating that the mean duration of effects in these two types of injections are significantly different from each other and with respect to mental and long buccal nerve. Mental and long buccal nerve are assigned a and ab, respectively indicating that mean duration effects in these two types of injections are not significantly different; LSD value = 4.787, the values in parenthesis are the ranges (minimum–maximum).

The χ 2 test applied to test the association between alcohol injection and efficacy in different branches of the trigeminal nerve found significance between these two variables ( χ 2 = 13.3714, P -value = 0.0039) at the 5% level of probability.

By applying one-way ANOVA, the alcohol injections in the inferior alveolar and infra-orbital nerve were found to be statistically significant ( P -value = <0.05; LSD value = 4.787). There was no significant difference between the average duration of effect of alcohol injection between the mental and long buccal nerves.

Alcohol injections were repeated. The interval between the first and subsequent injections was found to be 13.02 ± 4.92 months (range 2–45 months). There was a fall in the duration of effect of the subsequent injections ( Table 2 ). This difference in the repeated injections is statistically significant ( P < 0.05; LSD value = 2.331).

Feb 7, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Is peripheral alcohol injection of value in the treatment of trigeminal neuralgia? An analysis of 100 cases
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