High-concentration tetracaine for the management of trigeminal neuralgia: quantitative assessment of sensory function after peripheral nerve block

Trigeminal Neuralgia: Current Approaches and Emerging Interventions

Trigeminal neuralgia (TN) has been described in the literature as one of the most debilitating presentations of orofacial pain. This review summarizes over 150 years of collective clinical experience in the medical and surgical treatment of TN. Fundamentally, TN remains a clinical diagnosis that must be distinguished from other types of trigeminal neuropathic pain and/or facial pain associated with other neuralgias or headache syndromes. What is increasingly clear is that there is no catch-all medical or surgical intervention that is effective for all patients with trigeminal neuralgia, likely reflective of the fact that TN is likely a heterogenous group of disorders that jointly manifests in facial pain. The first-line treatment for TN remains anticonvulsant medical therapy. Patients who fail this have a range of surgical options available to them. In general, microvascular decompression is a safe and effective procedure with immediate and durable outcomes. Patients who are unable to tolerate general anesthesia or whose medical comorbidities preclude a suboccipital craniectomy may benefit from percutaneous methodologies including glycerol or radiofrequency ablation, or both. For patients with bleeding diathesis due to blood thinning medications who are ineligible for invasive procedures, or for those who are unwilling to undergo open surgical procedures, radiosurgery may be an excellent option-provided the patient understands that maximum pain relief will take on the order of months to achieve. Finally, peripheral neurectomies continue to provide an inexpensive and resource-sparing alternative to pain relief for patients in locations with limited economic and medical resources. Ultimately, elucidation of the molecular mechanisms underlying trigeminal neuralgia will pave the way for novel, more effective and less invasive therapies.

Trigeminal Neuralgia: Basic and Clinical Aspects

The trigeminal nerve is the largest of all cranial nerves. It has three branches that provide the main sensory innervation of the anterior two-thirds of the head and face. Trigeminal neuralgia (TN) is characterized by sudden, severe, brief, and stabbing recurrent episodes of facial pain in one or more branches of the trigeminal nerve. Pain attacks can occur spontaneously or can be triggered by non-noxious stimuli, such as talking, eating, washing the face, brushing teeth, shaving, a light touch or even a cool breeze. In addition to pain attacks, a proportion of the patients also experience persistent background pain, which along with autonomic signs and prolonged disease duration, represent predictors of worse treatment outcomes. It is now widely accepted that the presence of a neurovascular compression at the trigeminal root entry zone is an anatomic abnormality with a high correlation with classical TN. However, TN may be related to other etiologies, thus presenting different and/or additional features. Since the 1960s, the anticonvulsant carbamazepine is the drug of choice for TN treatment. Although anti-epileptic drugs are commonly used to treat neuropathic pain in general, the efficacy of carbamazepine has been largely limited to TN. Carbamazepine, however, is associated with dose-limiting side-effects, particularly with prolonged usage. Thus, a better understanding and new treatment options are urgently warranted for this rare, but excruciating disease.

Predictors of the Analgesic Efficacy of CT-Guided Percutaneous Pulsed Radiofrequency Treatment of Gasserian Ganglion in Patients With Idiopathic Trigeminal Neuralgia

AIMS

Although pulsed radiofrequency (PRF) has few postoperative adverse reactions, its analgesic efficacy for trigeminal neuralgia (TN) is not always guaranteed. The response rate of PRF targeting the Gasserian ganglion for patients with TN varies. This study aims to identify the predictors of the analgesic efficacy of CT-guided percutaneous PRF in patients with idiopathic TN.

METHODS

The patients with idiopathic TN who failed to respond to conservative treatment and underwent CT-guided percutaneous PRF treatment of the Gasserian ganglion from July 2008 to August 2018 at our pain clinic were screened. A positive response was defined as a ≥50% reduction in the pain numeric rating scale (NRS) score from baseline. The demographics and other pretreatment clinical data were analyzed by logistic regression analysis to identify the predictors of a positive response.

RESULTS

Of the total 102 patients with idiopathic TN who were evaluated in this study, 57 patients (55.9%) were positively responsive to our treatment after 1 year. The binary logistic regression analysis revealed that the positive response to a prior peripheral branch nerve block of the trigeminal nerve with steroid and local anesthetic agents was an independent predictor of the analgesic efficacy of PRF treatment (odds ratio [OR] = 3.685, 95% confidence interval [CI] = 1.583 to 8.577, P = 0.002). The disease duration of TN was also included in the multivariate regression model, although the P value was 0.058 (OR 0.807, 95% CI 0.646 to 1.007).

CONCLUSION

For patients who previously had positive responses to peripheral branch nerve block of the trigeminal nerve, PRF is likely to have better efficacy.

A systematic review of rescue analgesic strategies in acute exacerbations of primary trigeminal neuralgia

BACKGROUND

Trigeminal neuralgia (TN) can have a significant impact on wellbeing and quality of life. Limited data exist for treatments that improve TN pain acutely, within 24 h of administration. This systematic review aims to identify effective treatments that acutely relieve TN exacerbations.

METHODS

We searched Medline and Cochrane Central Register of Controlled Trials (CENTRAL) for relevant English language publications. The reference list for all articles was searched for other relevant publications. All studies that satisfied the following PICO criteria were included: (i) Population-adults with acute exacerbation of primary TN symptoms; (ii) Intervention-any medication or intervention with the primary goal of pain relief within 24 h; (iii) Comparator-usual medical care, placebo, sham or active treatment; (iv) Outcome-more than 50% reduction in pain intensity within 24 h of administration.

RESULTS

Of 431 studies, 17 studies were identified that reported immediate results of acute treatment in TN. The evidence suggests that the following interventions may be beneficial: local anaesthetic, mainly lidocaine (ophthalmic, nasal or oral mucosa, trigger point injection, i.v. infusion, nerve block); anticonvulsant, phenytoin or fosphenytoin (i.v. infusion); serotonin agonist, sumatriptan (s.c. injection, nasal). Other referenced interventions with very limited evidence include N-methyl-d-aspartate receptor antagonist (magnesium sulphate infusion) and botulinum toxin (trigger point injection).

CONCLUSIONS

Several treatment options exist that may provide fast and safe relief of TN. Future studies should report on outcomes within 24 h to improve knowledge of the acute analgesic TN treatments.

Infraorbital Foramen and Pterygopalatine Fossa Location in Dry Skulls: Anatomical Guidelines for Local Anesthesia

Purpose

The aim of the study was to locate the infraorbital foramen (IOF) in relation to the infraorbital margin (IOM) for proper injections of local anesthetics in skull specimens. Another aim was to determine the depth of needle penetration into pterygopalatine fossa through the greater palatine canal (GPC).

Materials and Methods

102 skull halves were used to measure the distances between (1) IOF and IOM and (2) IOF and alveolar ridge of maxilla at second premolar. Needles were inserted and bent at a 45° angle, passing through the GPC at the level of hard palate. The depth of the tip of needle emerging out of GPC into pterygopalatine fossa was measured.

Results

The mean distance between IOF and IOM was 6.46 ± 1.57 mm on the right side and 6.74 ± 1.72 mm on the left. The mean distance between IOF and alveolar bone process of the maxilla at second premolar was 29.07 ± 3.58 mm on the right side and 29.39 ± 3.78 mm on the left. The mean depth of penetration of the needle into the pterygopalatine fossa was similar on both sides.

Conclusions

Proper identification of IOF and pterygopalatine fossa is of great significance during local anesthesia injections, due to their close proximity to vital anatomic structures.

Peripheral nerve block with a high concentration of tetracaine dissolved in bupivacaine for intractable post-herpetic itch: a case report

Background

Post-herpetic itch (PHI) is a neuropathic itch syndrome following herpes zoster. It has been reported that PHI is occasionally sufficiently severe to compromise patients’ quality of life and frequently refractory to treatment. Here, we present a case of severe chronic PHI successfully treated with supraorbital nerve block using a high concentration of tetracaine dissolved in bupivacaine.

Case presentation

An 82-year-old man presented with severe chronic itching in the ophthalmic branch of the left trigeminal nerve dermatome, following acute herpes zoster. The patient’s itching was unresponsive to usual medical treatments for PHI including antiepileptic drugs, topical capsaicin cream, and supraorbital nerve radiofrequency thermo-coagulation. Topical lidocaine cream could relieve the itching, but could not provide long-term relief of itching and thus failed to achieve a satisfactory result. After these conventional treatments, left supraorbital nerve block using 4% tetracaine dissolved with 0.5% bupivacaine was conducted. Afterwards, the patient experienced long-lasting resolution of the itching with improvement of sleep disturbance. A transient, mild edema of the eyelids occurred, but there were no other complications.

Conclusions

Peripheral nerve block using 4% tetracaine dissolved with 0.5% bupivacaine was beneficial in relieving PHI in the ophthalmic division of the trigeminal nerve.

Effect of adding tetracaine to bupivacaine on duration of analgesia in supraclavicular brachial plexus nerve blocks for ambulatory shoulder surgery

The objective of this study was to determine if the addition of 1% tetracaine to 0.25% bupivacaine prolonged the duration of postoperative analgesia of supraclavicular brachial plexus nerve blockade for patients undergoing ambulatory shoulder surgery. We conducted a prospective, double-blinded, randomized controlled clinical study at an ambulatory surgery center utilizing ultrasound- and nerve stimulation-guided supraclavicular nerve blockade for postoperative analgesia. The control group received 30 mL of 0.25% bupivacaine plus 4 mL preservative-free saline. The study group received 30 mL of 0.25% bupivacaine plus 4 mL of 1% tetracaine. Patients documented their visual analog scale scores and intake of pain medications for 3 days. Primary outcomes included time of first postoperative pain, time of first postoperative pain pill, and time of return of motor and sensory function. Secondary outcomes included pain score and pain medication intake trends and adverse events secondary to the nerve block. A total of 84 patients completed the study, 42 patients in each group. The study group was statistically significantly older than the control group (mean age, 54 vs 48 years; P = 0.04). The mean duration of analgesia was 16.6 ± 8.3 h for the control group and 17.1 ± 7.3 h for the study group (P = 0.69). No outcomes were statistically different. In conclusion, there was no significant difference in duration of postoperative analgesia with the addition of 1% tetracaine to 0.25% bupivacaine in supraclavicular brachial plexus nerve blockade. No differences were identified in postoperative pain medications, pain scores, or complications.

Real-time ultrasound-guided infraorbital nerve block to treat trigeminal neuralgia using a high concentration of tetracaine dissolved in bupivacaine

Background Trigeminal neuralgia is a neuropathic disorder characterized by episodes of intense pain in the face. Drug therapy is the first choice of treatment. However, in cases where drug therapy are contraindicated due to side effects, patients can get pain relief from lengthy neurosurgical procedures. Alternatively, a peripheral trigeminal nerve block can be easily performed in an outpatient setting. Therefore it is a useful treatment option for the acute paroxysmal period of TN in patients who cannot use drug therapy. We performed real-time ultrasound guidance for infraorbital nerve blocks in TN patients using a high concentration of tetracaine dissolved in bupivacaine. In this report, we examine the efficacy of our methods. Patients As approved by the Institutional Review Board, the medical records in our hospital were queried retrospectively. Six patients with TN at the V2 area matched the study criteria. All patients could not continue drug therapy with carbamazepine due to side effects and they received an ultrasound-guided infraorbital nerve block with a high concentration of tetracaine dissolved in bupivacaine. Methods The patient was placed in the supine position and the patient's face was sterilized and draped. An ultrasound system with a 6-13 MHz linear probe was used with a sterile cover. The probe was inserted into the horizontal plane of the cheek just beside the nose and was slid in the cranial direction to find the dimple of the infraorbital foramen. The 25G 25 mm needle was inserted from the caudal side just across from the probe using an out-of-plane approach. To lead the needle tip to the foramen, needle direction was corrected with real-time ultrasound guidance. After the test block with lidocaine (2%, 0.5 ml), a solution of tetracaine (20 mg) dissolved in bupivacaine (0.5%, 0.5 ml) was injected. During each injection, the spread of the agent around the nerve was confirmed using ultrasound images. Results Ten blocks were performed for six patients. Immediately after the procedure, all 10 blocks produced analgesia and relieved the pain. In the three blocks, pain was experienced in a new trigger point outside of the infraorbital nerve region (around the back teeth) within a week after the block and pain were relieved using other treatment. Two patients developed small hematomas in the cheek but they disappeared in a week. All patients did not complain about other side effects including paraesthesia, hyperpathia, dysaesthesia, or double vision. Hypoaesthesia to touch and pain in the infraorbital region were observed in all blocks after 2 weeks. Conclusions We performed real-time ultrasound-guided infraorbital nerve block for TN with a high concentration of tetracaine dissolved in bupivacaine. Our method achieved a high success rate and there were only minor and transient side effects. Implications Real-time ultrasound-guided infraorbital nerve block is one of the useful options to treat the acute paroxysmal period of TN at the infraorbital nerve area. Ultrasound-guided injections may become the standard practice for injecting peripheral trigeminal nerves. Using this high concentration of tetracaine as a neurolytic agent is effective and appears to have only minor side effects.

Morphometric analysis and anatomical variations of infraorbital foramen: a study in adult North Indian population

PURPOSE

Various studies have been conducted on morphometric variations of infraorbital foramen to provide data to surgeons for nerve block in infraorbital region. This study aims to analyse the anatomical variations by comparing various morphometric measurements of infraorbital foramen in dry skulls of adult North Indian population. This study becomes relevant in the present study group as very scant data is available about the variations and morphometric measurements in Indian population. The data thus collected can be standardized and become useful for the surgeons working in this area of face.

MATERIALS AND METHODS

The study was conducted on 75 dry adult human skulls, which were a part of Department of Anatomy, used for teaching purposes in medical colleges. Straight distance of the Infraorbital foramen from the infraorbital rim, supraorbital foramen and sagittal plane was measured. The position of the infraorbital foramen was determined in relation to maxillary teeth and supraorbital foramen. The data thus obtained was analysed.

RESULTS

The distance of infraorbital foramen from infraorbital rim, supraorbital foramen, sagittal plane in the present study was found to be 6.71 ± 1.11 mm, 42.02 ± 4.31 mm and 31.94 ± 4.88 mm respectively. The position of infraorbital foramen was lateral in relation to supraorbital foramen (in 88% of cases). Infraorbital foramen was above the 1st premolar tooth in most of the cases. Accessory infraorbital foramen was found in 11.2% cases (double foramen).

CONCLUSION

The data thus obtained will perhaps be helpful to the surgeons in identifying the extent of the operative field thereby reducing procedural risks.

Immediate analgesic effect of 8% lidocaine applied to the oral mucosa in patients with trigeminal neuralgia

BACKGROUND

Trigeminal nerve block is widely used for trigeminal neuralgia (TN), though with much painful procedure and potential serious complications. The pain of TN occurs most frequently in the second and the third divisions of the trigeminal nerve, which are distributed in intraoral mucous membrane as well as face skin. Here, we examined the response to intraoral application of 8% lidocaine (LDC) in patients with oral TN pain in a double-blind, placebo (PBO)-controlled crossover study.

METHODS

Twenty-four outpatients with oral TN pain were randomized to receive intraoral application of either 8% LDC or saline PBO to the painful area. Following 7-days period, patients were crossed over to receive the alternative treatment. The pain was assessed with a numerical rating scale (NRS) before and 15 minutes after treatment. Patients used a descriptive scale to grade pain outcome and were asked to note any recurrence and the latency for recurrence after therapy.

RESULTS

Intraoral LDC, but not PBO, significantly decreased the NRS from 5 (4, 8) (median [25, 75 percentiles]) to 1 (0, 4) (P = 0.001). Of the 24 patients, 19 described marked or moderate relief of pain after LDC but only three described the same after PBO application. The effect of LDC and PBO persisted for 2.8 (0.3, 3.0) and 0 (0, 0) hours, respectively.

CONCLUSIONS

Intraoral application of 8% LDC produced prompt analgesia without serious side effects in patients with TN who presented with severe intraoral pain.

Can the neurovascular compression volume of the trigeminal nerve on magnetic resonance cisternography predict the success of local anesthetic block after initial treatment by the carbamazepine?

OBJECTIVES

Whether NVC volume on magnetic resonance (MR) cisternography might be related to the success of local anesthetic block by tetracaine (TNB) as an additional treatment after carbamazepine (CBZ) treatments in patients with trigeminal neuralgia (TN) was evaluated.

STUDY DESIGN

Detectable NVC volumes were measured from MR cisternography in 65 patients with TN treated by TNB after CBZ treatments. The correlation between the success of TNB and the NVC volume or the improvement in pain by CBZ was evaluated retrospectively.

RESULTS

A significant difference was found between the improvement in pain by CBZ and the success of TNB, but not between NVC volume on MR cisternography and the success of TNB.

CONCLUSIONS

The present results suggest that the success of CBZ as initial treatment, but not NVC volume on MR cisternography, may be a significant predictor of the success of TNB as additional therapy in patients with TN.

Treatment of trigeminal neuralgia with bupivacaine HCL using a temporary epidural catheter and pain pump: preliminary study

OBJECTIVES

Trigeminal neuralgia (TN) is a rare form of neuropathic facial pain characterised by severe paroxysmal pain in the face. The treatment for trigeminal neuropathic pain disorder continues to be a major therapeutic challenge, as relief provided by medical therapy generally decreases over time. When medical therapy fails either due to poor or diminishing responses to drugs or to unacceptable side effects, peripheral intervention or surgical management of TN should be considered.

STUDY DESIGN

Fourteen patients (eight men and six women) who were not responsive to further medical treatment and who were diagnosed with TN previously at other health centres were selected for treatment. For this purpose, the affected nerve was infused with 60 mL (1 mL h(-1)) of 0.5% bupivacaine HCl with a pain pump via an temporary epidural catheter. Patient's visual analogue scores (VAS) were recorded on the fifth preoperative day and on postoperative day 5, 2 weeks, 1, 3, 6 and 9 months.

RESULTS

There was a significant difference between mean preoperative and postoperative VAS value at day 5, 2 weeks, 1, 3, 6 and at the end of 9 months ((68.85 ± 1.43) (13.57 ± 6.68) (11.43 ± 6.70) (14.29 ± 6.52) (20.71 ± 6.41) (20.71 ± 6.41) and (21.43 ± 6.10) respectively; ∗P<0.05). Two of 14 patients did not show any pain relief.

CONCLUSIONS

Continuous administration of 60 mL of 0.5% bupivacaine HCl at 1 mL h(-1) with a pain pump and epidural catheter can be used as a transition treatment for patients with side effects from high-dose antiepileptic drugs and for patients awaiting neurosurgery or individuals who refuse cranial surgery. It should not be considered as an alternative treatment of neurosurgical approaches, such as MVD, which has a definite long-lasting results.

Morphometric analysis of infraorbital foramen in Indian dry skulls

We analyzed the variability in position, shape, size and incidence of the infraorbital foramen in Indian dry skulls as little literature is available on this foramen in Indians to prevent clinical complications during maxillofacial surgery and regional block anesthesia. Fifty-five Indian skulls from the Department of Anatomy CSM Medical University were examined. The 110 sides (left and right) of the skulls were analyzed by measuring the infraorbital foramina distances from infraorbital margin and the piriform aperture on both sides. The vertical and horizontal dimensions were also measured. All measurements were taken with a compass transferred to calipers and analyzed statistically. The mean distances between the infraorbital foramen and the infraorbital margin on the right and left side were 6.12 mm and 6.19 mm, respectively. The mean distances between the infraorbital foramen and the piriform aperture were 15.31 mm and 15.80 mm on the right and left sides, respectively. The mean vertical dimensions on the right and left side were 3.39 mm and 3.75 mm, respectively. The mean horizontal dimensions on the two sides were 3.19 mm and 3.52 mm. These results provide detailed knowledge of the anatomical characteristics and clinical importance of the infraorbital foramina which are of paramount importance for surgeons when performing maxillofacial surgery and regional block anesthesia.

Local anesthetic blockade of peripheral nerves for treatment of neuralgias: systematic analysis

BACKGROUND

Nerve blocks with local anesthetics have been used in the diagnosis and treatment of neuralgias. Usually these blocks were administered in combination with corticosteroids and other drugs that can be effective by themselves. Although lasting benefits from nerve blocks in neuralgias have long been described, definitive evidence is lacking. We had the following objectives in this systematic review: to analyze the evidence behind the practice of peripheral nerve blockade with local anesthetics in patients with neuralgias and radicular pain syndromes; to assess the duration of pain relief after conduction block resolution; and to evaluate the effectiveness of the treatment of these syndromes with a series of blocks.

METHODS

We searched Medline, Embase, narrative reviews, and book chapters. Only articles published in English were collected. The list of 3347 identified articles was reduced to 39 articles that were read entirely, 12 of which met inclusion criteria.

RESULTS

Twelve included articles were analyzed. Each can be classified as a single case report or case series; there were no controlled studies among them. Nine reports assessed a single block outcome; all recorded pain relief beyond the duration of conduction blockade. Those 9 reports represented a total of 69 patients, 30 of whom had complete pain relief and 10 had relief ≥50%. Seven reports with the assessment of continuous pain ≥1 week after a single block reported complete or profound pain relief in 11 of 17 patients. All 3 reports with the assessment of a series of blocks in a large number of patients (total of 270) reported overall positive results.

CONCLUSION

Because all reviewed articles were only single case reports or case series, no reliable conclusion could be drawn concerning the effectiveness of nerve blocks with local anesthetics in neuralgia. However, 2 features of the analyzed reports-the large magnitude of the effect and the high consistency of the reported outcome-indicate that future research efforts are warranted.

Topical ophthalmic amethocaine alleviates trigeminal neuralgia pain

Background

Trigeminal neuralgia (TGN) is a challenging pain syndrome.

Aim

To test the effectiveness of local instillation of ophthalmic solution of amethocaine in relieving the pain of TGN.

Methods

We performed an open-label prospective study in 40 consecutive currently treated patients suffering from TGN with a reported visual analog scale (VAS) >8 (severe pain). The patients received two drops of amethocaine 1% instilled on the cornea ipsilateral to the painful side. Pain score assessment using VAS was recorded pre- and post-treatment.

Results

A total of 32 (80%) patients reported a significant reduction in pain 10 minutes after drops instillation as compared with pre-treatment pain score. Pre-treatment VAS score was 8.53 ± 0.6 as compared with 4.78 ± 1.83 post-amethocaine treatments (P < 0.00001).

Conclusion

Topical ophthalmic instillation of amethocaine 1% can be considered as an immediate effective method for pain paroxysm of TGN.

Anatomic study of the infraorbital foramen for radiofrequency neurotomy of the infraorbital nerve

OBJECTIVE

To examine the anatomy of the infraorbital canal and foramen and the angles at which a radiofrequency probe must be directed to enter the infraorbital foramen and canal, as a guide to performing radiofrequency ablation of the infraorbital nerve in patients with relative or absolute contraindications to lesions of the trigeminal ganglion or posterior root.

METHODS

Eleven cadaveric skulls were studied. The infraorbital nerve, after passing through the infraorbital foramen, enters the infraorbital canal and groove in the floor of the orbit before reaching the foramen rotundum. Small probes were placed through the foramen into the infraorbital canal, and pictures were taken in the anteroposterior and sagittal planes. The pictures were analyzed using the ImageTool program (University of Texas Health Science Center, San Antonio, TX) to calculate the anteroposterior and sagittal angles of the probe. The distances of the foramen from the midline, lateral edge of the anterior nasal aperture, and inferior orbital rim were examined.

RESULTS

A probe introduced through the cheek from below and medial to the foramen and directed upward and laterally at an angle of approximately 22 degrees in the coronal plane and 120 degrees in the sagittal plane toward a point approximately 26 mm from the midline and 8 mm below the inferior orbital rim will penetrate the infraorbital foramen for placement of the probe's tip in the infraorbital canal.

CONCLUSION

The coordinates for placement of the radiofrequency probe through the infraorbital foramen and into the infraorbital canal are reviewed, along with a discussion of pitfalls in radiofrequency ablation of the nerve.

Efficacy and safety of high concentration lidocaine for trigeminal nerve block in patients with trigeminal neuralgia

AIMS

Local anaesthetics, which act as neurolytics and Na(+) channel blockers, have been used for disrupting the neural firings in certain neuropathic pain conditions. This study was undertaken to investigate the clinical outcome of trigeminal nerve block with 10% lidocaine in the management of trigeminal neuralgia (TN).

METHODS

Thirty-five patients with primary TN received trigeminal nerve blocks with 10% lidocaine. Success was defined as complete pain relief or mild pain without medication 1 day after the treatment. We followed the patients up every 2 months assessing for pain recurrence, sensory changes and other complications for a total of 37-45 months (median 43 months).

RESULTS

Twelve of the 35 patients (34.3%) responded favourably to the treatment and were considered as success. Eleven patients experienced complete pain relief and one could tolerate pain without medication 1 day after the blocks, which lasted for 3-172 weeks. Four patients experienced mildly decreased sensation in the region of the face supplied by the nerve 1 day after the blocks; however, all recovered normal skin sensation in 6 months. There was neither allodynia nor other sensory discomfort. The pain intensity and current pain duration before treatment were significantly different between the two groups.

CONCLUSION

Trigeminal nerve block with high concentration lidocaine (10%) is capable of achieving an intermediate period of pain relief, particularly in patients with lower pain intensity and shorter pain duration prior to the procedure.

Two cases of idiopathic superior laryngeal neuralgia treated by superior laryngeal nerve block with a high concentration of lidocaine

Carbamazepine therapy is among the most effective drug regimens to treat patients who have superior laryngeal neuralgia similar to trigeminal neuralgia. However, some patients are resistant to carbamazepine. We report two patients with superior laryngeal neuralgia who were successfully treated with superior laryngeal block using high concentrations of lidocaine, after treatment with carbamazepine failed.