Operative treatment of trigeminal neuralgia: review of current techniques

Neuronavigation-guided Percutaneous Rhizotomies to Trigeminal Neuralgia: A Systematic Review

OBJECTIVE

Neuronavigation improves intraoperative visualization of the cranial structures, which is valuable in percutaneous surgical treatments for patients with trigeminal neuralgia (TN) who are refractory to pharmacotherapy or reluctant to receive open surgery. The objective of this review was to evaluate the available neuronavigation-guided percutaneous surgical treatment modalities with cannulation of foramen ovale to TN, and their relative benefits and limitations.

METHODS

This review was conducted based on the PRISMA statement. An initial search was performed on electronic databases, followed by manual and reference searches. Study and patient characteristics, rhizotomy procedure and neuronavigation details, and treatment outcomes (initial pain relief and pain recurrence within 2 y, success rate of forman ovale cannulation, and complications) were evaluated. The risk of bias was assessed with a quality assessment based on the ROBINS-I tools.

RESULTS

Ten studies (491 operations, 403 participants) were analyzed. Three percutaneous trigeminal rhizotomy modalities identified were radiofrequency thermocoagulation rhizotomy (RFTR), percutaneous balloon compression, and glycerol rhizotomy. Intraoperative computed tomography and magnetic resonance imaging fusion-based RFTR had the highest initial pain relief rate of 97.0%. The success rate of foramen ovale cannulation ranged from 92.3% to 100% under neuronavigation. Facial hypoesthesia and masticatory muscle weakness were the most reported complications.

DISCUSSION

Neuronavigation-guided percutaneous trigeminal rhizotomies showed possible superior pain relief outcomes to that of conventional rhizotomies in TN, with the benefits of radiation reduction and lower complication development rates. The limitations of neuronavigation remain its high cost and limited availability. Higher-quality prospective studies and randomized clinical trials of neuronavigation-guided percutaneous trigeminal rhizotomy were lacking.

Anatomic Variations of Foramen Ovale as a Predictor of Successful Cannulation in Percutaneous Trigeminal Rhizotomies

BACKGROUND AND OBJECTIVES

Percutaneous trigeminal rhizotomies are common treatment modalities for medically refractory trigeminal neuralgia (TN). Failure of these procedures is frequently due to surgical inability to cannulate the foramen ovale (FO) and is thought to be due to variations in anatomy. The purpose of this study is to characterize the relationships between anatomic features surrounding FO and investigate the association between anatomic morphology and successful cannulation of FO in patients undergoing percutaneous trigeminal rhizotomy.

METHODS

A retrospective analysis was conducted of all patients undergoing percutaneous trigeminal rhizotomy for TN at our academic center between January 1, 2010, and July 31, 2022. Preoperative 1-mm thin-cut computed tomography head imaging was accessed to perform measurements surrounding the FO, including inlet width, outlet width, interforaminal distance (a representation of the lateral extent of FO along the middle fossa), and sella-sphenoid angle (a representation of the coronal slope of FO). Mann-Whitney U tests assessed the difference in measurements for patients who succeeded and failed cannulation.

RESULTS

Among 37 patients who met inclusion criteria, 34 (91.9%) successfully underwent cannulation. Successful cannulation was associated with larger inlet widths (median = 5.87 vs 3.67 mm, U = 6.0, P = .006), larger outlet widths (median = 7.13 vs 5.10 mm, U = 14.0, P = .040), and smaller sella-sphenoid angles (median = 52.00° vs 111.00°, U = 0.0, P < .001). Interforaminal distances were not associated with the ability to cannulate FO surgically.

CONCLUSION

We have identified morphological characteristics associated with successful cannulation in percutaneous rhizotomies for TN. Preoperative imaging may optimize surgical technique and predict cannulation failure.

New insight into the mandibular nerve at the foramen ovale level for percutaneous radiofrequency thermocoagulation

Background

Percutaneous radiofrequency thermocoagulation (RFTC) has been widely utilized in the management of trigeminal neuralgia. Despite using image guidance, accurate needle positioning into the target area still remains a critical element for achieving a successful outcome. This study was performed to precisely clarify the anatomical information required to ensure that the electrode tip is placed on the sensory component of the mandibular nerve (MN) at the foramen ovale (FO) level.

Methods

The study used 50 hemi-half heads from 26 South Korean adult cadavers.

Results

The cross-sectioned anterior and posterior divisions of the MN at the FO level could be distinguished based on an irregular boundary and color difference. The anterior division was clearly brighter than the posterior one. The anterior division of the MN at the FO level was located at the whole anterior (38.0%), anteromedial (6.0%), anterior center (8.0%), and anterolateral (22.0%) parts. The posterior division was often located at the whole posterior or posterolateral parts of the MN at the FO level. The anterior divisions covered the whole MN except for the medial half of the posterolateral part in the overwrapped images of the cross-sectional areas of the MN at the FO level. The cross-sectional areas of the anterior divisions were similar in males and females, whereas those of the posterior divisions were significantly larger in males (P = 0.004).

Conclusions

The obtained anatomical information is expected to help physicians reduce unwanted side effects after percutaneous RFTC within the FO for the MN.

Personal experience with microvascular decompression and partial sensory rhizotomy for trigeminal neuralgia

Background

Trigeminal neuralgia (TN) is a severe, paroxysmal pain in the distribution of the fifth cranial nerve. Microvascular decompression (MVD) is the most widely used surgical treatment for TN. We undertook this study to analyze the effects of and complications of MVD and to refine the surgical procedure for treating TN.

Methods

A total of 88 patients underwent for TN underwent surgery at our hospital. Among them, 77 patients underwent MVD alone, and 11 underwent partial sensory rhizotomy (PSR) with or without MVD. The medical records of these patients were retrospectively analyzed for patient characteristics, clinical results, offending vessels, and complications if any.

Results

The mean follow-up duration was 43.2 months (range, 3–216 months). The most common site of pain was V2+V3 territory (n=27), followed by V2 (n=25) and V3 (n=23). The most common offending vessels were the superior cerebellar artery and anterior inferior cerebellar artery in that order. The overall rate of postoperative complications was 46.1%; however, most complications were transient. There were two cases of permanent partial hearing disturbance. In the MVD alone group, the cure rate was 67.5%, and the improvement rate was 26.0%. Among 11 patients who underwent PSR with or without MVD, the cure rate was 50.0%, and the improvement rate was 30.0%.

Conclusion

The clinical results of MVD were satisfactory. Although the outcomes of PSR were not as favorable as those of pure MVD in this study, PSR can be considered in cases where there is no significant vascular compressive lesion or uncertainty of the causative vessel at the surgery.

Histopathological Evaluation of Inferior Alveolar Neurovascular Bundle in Cases of Trigeminal Neuralgia

Background

Trigeminal neuralgia is a painful disease that has been afflicting mankind since time immemorial. The etiology and pathophysiology have been widely studied but poorly understood. There are well-documented researches analyzing ultrastructural changes in trigeminal root specimens obtained following microvascular decompression surgery. However, there are no studies evaluating microscopic changes following peripheral neurectomy.

Purpose

The present study examined microscopic changes in inferior alveolar neurovascular bundle in trigeminal neuralgia patients of mandibular division with no underlying cause.

Materials and Methods

The biopsy specimens were obtained from peripheral neurectomy of 11 trigeminal neuralgia patients' refractory to anti-neuralgic medications. The autopsy specimens from 10 cadavers were used as control. The specimens were subjected to histopathological examination by hematoxylin and eosin, Masson trichrome and Luxol fast blue stains.

Results

All biopsy specimens reported luminal occlusion of small vessels, medial degeneration and intense mononuclear inflammatory infiltrate. Focal myelin digestion chambers were observed in large and small axons. No pathological alterations of either blood vessel or nerve fibers were reported in autopsy specimens.

Conclusion

The demyelination of inferior alveolar nerve due to pathologic vascular changes in peripheral vasculature may have a role in initiation and precipitation of trigeminal neuralgia, and hence, peripheral neurectomy has a significant role in alleviating pain.

Radiofrequency Ablation for Treating Headache

PURPOSE OF REVIEW

Examining the efficacy of radiofrequency ablation in treating headache conditions.

RECENT FINDINGS

The efficacy of radiofrequency ablation in treating headache conditions is not well studied. Chronic headache conditions can be difficult to treat with little consensus on management of headaches associated with pericranial neuralgias. In this retrospective study, we found that radiofrequency ablation is an effective and safe treatment for resistant headache conditions. This study is important as it describes a novel treatment for chronic headache which can benefit a large number of patients.

Computer-Assisted Design Template Guided Percutaneous Radiofrequency Thermocoagulation through Foramen Rotundum for Treatment of Isolated V2 Trigeminal Neuralgia: A Retrospective Case-Control Study

Objective

Radiofrequency thermocoagulation (RFT) through the foramen rotundum has emerged as an alternative for treatment of isolated V2 trigeminal neuralgia. But puncture of the foramen rotundum is difficult and time-consuming. In current study, we introduced the application of a computer-assisted design (CAD) template to guide foramen rotundum cannulation. Meanwhile, we assessed its safety and efficacy in the treatment of isolated V2 trigeminal neuralgia.

Methods

From November 2015 to August 2017, thirty-eight patients with isolated V2 trigeminal neuralgia were treated with computed tomography- (CT-) guided RFT through the foramen rotundum in our institution. All cases were reviewed, and patients were divided into the experimental group (n=17, puncture with a CAD template) and control group (n=21, free-hand puncture) according to the puncture method used. The puncture times, duration of puncture, and duration of operation were collected. The outcome of pain remission was evaluated utilizing the Barrow Neurological Institute's (BNI) pain score. Complications and recurrence of pain were also recorded. Data were compared between groups.

Results

The rate of one-time successful puncture in the experimental group was obviously higher than that in the control group. Mean puncture times in the experimental group was fewer. Average duration of puncture and operation in the experimental group was also shorter than that in the control group. All patients experienced good pain remission (BNI Class I or II) postoperatively. At four follow-up points (7 days, 3 months, 6 months, and 12 months after operation), there was no significant difference in good pain relief rate between the two groups. Meanwhile, no significant difference was found in complications.

Conclusions

CAD template is a safe and precise navigation instrument for RFT treatment of isolated V2 trigeminal neuralgia via the foramen rotundum. Therefore, this novel tool is worthy of clinical promotion.

Immediate and Long-Term Outcomes of Microvascular Decompression for Mixed Trigeminal Neuralgia

BACKGROUND

Classic trigeminal neuralgia (TN) involves sharp, shooting pain in any trigeminal nerve distribution, whereas atypical TN presents with constant aching, numbness, or burning that can appear with classic features, leading to a mixed presentation. Microvascular decompression (MVD) is an effective treatment for classic TN, but its utility in treating mixed TN has been less well studied.

METHODS

We retrospectively studied 73 adult patients with mixed TN and 386 patients with classic TN who underwent MVD between December 2007 and October 2016. Recorded variables included demographic data, graded radiologic and intraoperative findings, and graded pain outcomes in the immediate postoperative period (up to 3 months after MVD) and during long-term follow-up.

RESULTS

The mean age of the 73 patients with mixed TN was 53.2 years. In terms of immediate postoperative outcomes, 67 patients (91.8%) experienced pain relief including improvement of atypical pain, whereas 6 patients (8.2%) had no pain relief. Having a preexisting pain syndrome (P = 0.001) or distortion of the trigeminal nerve intraoperatively (P = 0.001) was associated with poor surgical outcome in the patients with mixed TN. The mean duration of follow-up was 20.6 months. Forty-four patients (60.3%) developed recurrence of any TN pain. In comparison, 93% of the patients with classic TN experienced pain relief in the immediate postoperative period, and the recurrence rate was 19.9% in these patients.

CONCLUSIONS

Patients with mixed TN suffer from both classic and atypical TN symptoms. Following MVD, 91.8% of our patients with mixed TN reported partial or complete pain relief, including improvement of atypical pain, in the immediate postoperative stage, compared with 93% of those with classic TN. Recurrence eventually developed in 60.3% of the patients with mixed TN.

Efficacy of Neurectomy of Peripheral Branches of the Trigeminal Nerve in Trigeminal Neuralgia: A Critical Review of the Literature

Introduction

Of the many chronic painful conditions, trigeminal neuralgia (TN) affecting the orofacial region needs the particular attention of physicians and surgeons, especially those specialising in the maxillofacial region. Treatment protocols for the management of classic TN include pharmacology and surgical intervention. Oral and maxillofacial surgeons have traditionally employed the peripheral neurectomy in the surgical management of TN. This review aims to evaluate the efficacy of peripheral neurectomy in the management of TN with regard to (a) the relief of symptoms in comparison with standard neurosurgical procedures and (b) the duration of pain relief and complications observed compared to standard neurosurgical procedures.

Methods

The review of the literature was done according to PRISMA guidelines and included randomised controlled trials, reviews and prospective clinical studies involving surgical procedures for the management of TN. The primary outcomes evaluated were (a) initial relief of pain, (b) duration of relief of pain, (c) complications observed with ablative procedures and (d) recurrence of symptoms. A total of 43 studies fulfilled the inclusion criteria.

Results

In a total of 7913 patients from the 43 studies, central procedures were found to have best results for both quality and duration of pain relief. Percutaneous and peripheral procedures were associated with increased recurrence rates. The consolidated rates of complication for peripheral, percutaneous and central procedures were 39.46, 65.42 and 10.41%, respectively. The use of peripheral neurectomy alone in the management of classic TN was observed in 10 studies.

Conclusion

Peripheral neurectomy in TN is associated with lesser quality of pain relief in comparison with central neurosurgical procedures. It also provides only short- to medium-term pain relief. Most studies with the use of peripheral neurectomy involved only a small group of patients with short follow-up periods. Oral and maxillofacial surgeons must not consider the peripheral neurectomy as the first surgical option in the management of classic TN. Long-term results can be achieved better with appropriate central neurosurgical procedures and pharmacotherapy.

Assessing and treating primary headaches and cranio-facial pain in patients undergoing rehabilitation for neurological diseases

BACKGROUND

Pain is a very common condition in patient undergoing rehabilitation for neurological disease; however the presence of primary headaches and other cranio-facial pains, particularly when they are actually or apparently independent from the disability for which patient is undergoing rehabilitation, is often neglected. Diagnostic and therapeutic international and national guidelines, as well as tools for the subjective measure of head pain are available and should also be applied in the neurorehabilitation setting. This calls for searching the presence of head pain, independently from the rehabilitation needs, since pain, either episodic or chronic, interferes with patient performance by affecting physical and emotional status. Pain may also interfere with sleep and therefore hamper recovery.

METHODS

In our role of task force of the Italian Consensus Conference on Pain in Neurorehabilitation (ICCPN), we have elaborated specific recommendations for diagnosing and treating head pains in patients undergoing rehabilitation for neurological diseases.

RESULTS AND CONCLUSION

In this narrative review, we describe the available literature that has been evaluated in order to define the recommendations and outline the needs of epidemiological studies concerning headache and other cranio-facial pain in neurorehabilitation.

CT-guided selective percutaneous radiofrequency thermocoagulation via the foramen rotundum for isolated maxillary nerve idiopathic trigeminal neuralgia

OBJECTIVE Although CT-guided selective percutaneous radiofrequency thermocoagulation (PRFT) via the foramen rotundum (FR) has been used in the clinic as a novel successful treatment for isolated, second division (maxillary nerve [V2]), idiopathic trigeminal neuralgia (ITN), there is only very limited related literature published to date. This report aims to provide more detail for physicians about this technique. METHODS Between March 2013 and April 2014, 20 patients with isolated V2 ITN refractory to or intolerant of drug treatment were treated by CT-guided selective PRFT via the FR at the First Affiliated Hospital of Nanchang University. The outcome of pain relief was assessed using the Barrow Neurological Institute (BNI) pain score, and grouped as good (BNI Class I or II, no medication required) and bad (BNI Class III-V, medication required or failed). Recurrence was defined as a relapse to a previous lower level after attainment of any higher level of pain relief. Adverse effects and complications were also monitored and recorded. RESULTS All patients (100%) obtained good pain relief including BNI Class I in 17 patients (85%) and BNI Class II in 3 patients (15%) immediately postoperatively. None of the patients were lost to follow-up. During the mean follow-up period of 24.3 months (range 18-30 months), 2 patients (10%) experienced recurring pain and the mean time until recurrence was 10.5 months (range 8-13 months). No adverse effects or complications occurred except for transient numbness restricted to the V2 dermatome in all patients (100%) and facial hematoma in 3 patients (15%). CONCLUSIONS In the current study, CT-guided selective PRFT via the FR not only achieved absolute selective lesioning to V2, but also helped patients attain successful pain relief with few adverse effects. These limited data suggest that CT-guided selective PRFT via the FR appears to be a feasible, safe, effective, and even relatively ideal treatment for isolated V2 ITN, but these findings need confirmation from further studies.

Minimizing technical failure of percutaneous balloon compression for trigeminal neuralgia using neuronavigation

Objective. Percutaneous balloon compression (PBC) is an effective and safe management for medically refractory trigeminal neuralgia; however, technical failure to cannulate the foramen ovale (FO) using only fluoroscopy is a significant problem in some cases. In this paper, we suggest the use of intraoperative navigation, in cases of reoperation due to prior technical failure to cannulate the FO under fluoroscopy. Methods. A total of 174 patients underwent PBC for TN since 2003. In 9 cases the penetration of the FO was not accomplished. Five of those patients were reoperated on for PBC using navigation from March 2012 to September 2012.

SURGICAL TECHNIQUE

preoperatively, a head Computed Tomography (CT) scan is performed and the acquired images are imported into the navigation system. Intraoperatively, a small reference frame is strapped firmly to the patient's forehead, the CT images are registered, and cannulation is performed under the guidance of the navigation system. Results. In all patients, the operation overall was completed successfully. Moreover, all patients reported complete pain relief immediately postoperatively and no complications were recorded overall. Conclusions. We suggest the use of neuronavigation in cases of technical failure of PBC. That technique involves technology with significant advantages helping the successful cannulation of the FO and seems more efficient and safer.

Role of transcutaneous electric nerve stimulation in the management of trigeminal neuralgia

BACKGROUND

Trigeminal neuralgia typically involves nerves supplying teeth, jaws and face of older females. Though the etiology is usually obscure, different treatment modalities have been tried for it viz. medicinal treatment, injection alcohol, peripheral neurectomy, rhizotomy, and microvascular decompression etc. Transcutaneous electric nerve stimulation (TENS) is an emerging and promising option for management of such patients.

AIMS AND DESIGN

The present study was designed with an aim to study the efficacy of TENS in management of trigeminal neuralgia.

MATERIALS AND METHODS

The study was conducted on 30 patients of trigeminal neuralgia confirmed by diagnostic nerve block. They were given bursts of TENS for 20-40 days over the path of the affected nerve and subsequently evaluated at 1 month and 3 month intervals by visual analogue scale (VAS), verbal pain scale (VPS), a functional outcome scales for main daily activities like sleep, chewing, talking, or washing face.

RESULTS

The results showed that, on VAS, the score decreased from 8.9 (Pre TENS) to 3.1 at 1 month and 1.3 at 3 months, and on VPS, the score decreased from 3.5 (Pre TENS) to 1.2 at 1 month and 0.3 at 3 months. Similarly, a considerable decrease in scores was seen on functional outcome scale for different activities. No side effects like irritation or redness of skin were seen in any of the patients.

CONCLUSIONS

Thus, TENS was found to be a safe, easily acceptable, and non-invasive outdoor patient department procedure for management of trigeminal neuralgia.

Peripheral neurectomy: minimally invasive surgical modality for trigeminal neuralgia in Indian population: a retrospective analysis of 20 cases

OBJECTIVE

To evaluate the efficacy of peripheral neurectomy in 20 cases of trigeminal neuralgia as minimally invasive surgical treatment modality.

MATERIALS AND METHODS

Twenty (12 males and 8 females) patients with trigeminal neuralgia aged between 35 and 68 years (mean 48 years), who had undergone peripheral neurectomy, were retrospectively analyzed for relief of pain, complications, recurrence of pain, and any additional procedure required to treat recurrence, in a follow-up period of 36 months postoperatively.

RESULTS

There was no significant intra-operative and post-operative complications. There was recurrence of pain in two patients (10 %) in 24 and 28 months post-operative follow-up respectively, whereas, rest of the 18 patients were symptom free during 36 months follow-up.

CONCLUSION

Peripheral neurectomy is one of the minimally invasive and expeditious forms of surgical modality for the treatment of trigeminal neuralgia. This treatment option is cost effective and provides long term relief from neuralgic pain.

A recurrent variant branch of the inferior alveolar nerve: is it unique?

The only named branch of the inferior alveolar nerve (IAN) before it enters the mandibular foramen is the mylohyoid nerve. However, several variations have been reported in the literature. In this study, a recurrent variant branch of the IAN arising just below the origin of the mylohyoid nerve was investigated in adult Indian cadavers allotted for dissection to the first year dental students of Government Dental College, Ahmedabad (India). The dissection was performed by the lateral approach to the infratemporal fossa. The nerve was found in 12 of 35 sides (34.3%) and 8 of 18 cadavers (44.4%). Thus, in our study it was not a rare variation of the IAN, where in most cases it innervated the lateral pterygoid muscle. In some cases, it terminated in the lateral pterygoid muscle. In others, it penetrated the muscle to join the anterior or posterior division of the mandibular nerve or its branches; thus, the variant nerve in such cases might be regarded as an additional root of the IAN. Because the concerned primordia of the nerves and muscles migrate extensively during development and growth, alternative routes of migration may bring about variants like the one under study. The variant appeared to be unique in some of its features. It may be a source of neuropathic and referred pain. Failure of the conventional inferior alveolar nerve block anesthesia and the peripheral neurectomy used for the treatment of trigeminal neuralgia may be partly due to the presence of this variation.

Use of single- and multi-drug regimens in the management of classic (idiopathic) trigeminal neuralgia: an 11-year experience at a single Sri Lankan institution

AIM

The aim of this retrospective study was to evaluate the outcome of medical treatment of classic trigeminal neuralgia and to assess the factors affecting the choice of drug regimen (single or multiple), and the duration of treatment for pain control.

METHODS

A total of 260 consecutive patients were included in the study. Sixty-one patients with less than 6 months' follow up were excluded. All patients were treated with carbamazepine alone or in combination with other drugs. The dosage was adjusted according to the level of pain control and side-effects.

RESULTS

Treatment was terminated in 99 patients (49.7%) after a mean follow-up period of 36.46 months (standard deviation: ±26.5). Of these, 39.4% were on a single drug. Carbamazepine was the drug used in 36 patients. The rest (61%) needed various combinations of drugs. One-hundred patients (50.3%) continued with medical treatment during the follow-up period. Of these, 67.4% were on multi-drug therapy.

CONCLUSION

The present study showed that the administration of multidrug regimens is a useful alternative in controlling trigeminal neuralgia in patients who are unable to tolerate higher doses of carbamazepine. Age, sex, ethnicity, and the side of affliction did not have a significant influence on the choice of drug regimen and the duration of treatment for pain control.

Peripheral neurectomy: a minimally invasive treatment for trigeminal neuralgia. A retrospective study

AIM

Investigate the efficacy of peripheral neurectomy as a surgical procedure in the treatment of trigeminal neuralgia and to evaluate the results obtained by this procedure and their recurrences in a period of three years followup.

MATERIALS AND METHODS

Thirty patients were retrospectively reviewed who underwent peripheral neurectomy. The factors analyzed were the demographic details of the patients, side of involvement, branch of nerve involved and procedure used postoperative complications, prognosis and any additional procedure used in cases of recurrences.

RESULTS

The mean age of the patient was 57.1 years (range 35-71 years) more were males (M:F = 1.73:1) and the surgical treatment was peripheral neurectomy of the involved branch following failure of carbamazepine therapy. There was no intra operative and postoperative complications noted and follow up over 3 years revealed only two cases (6.66%) of recurrence. Two patients were lost to followup, total number evaluated between 0 and 3 years after treatment was 28 patients.

CONCLUSION

Peripheral neurectomy is one of the oldest, minimal invasive forms of surgery, well tolerated by the patient and can be done under local anesthesia.

Masseter muscle function after percutaneous balloon compression of trigeminal ganglion for the treatment of trigeminal neuralgia: a neurophysiological follow-up study

OBJECTIVE

We aimed to evaluate by longitudinal neurophysiological examinations the natural course of masseter muscle weakness that developed after percutaneous balloon compression (PBC) of the trigeminal ganglion for the treatment of idiopathic trigeminal neuralgia.

METHODS

The affected side of 15 patients (mean age 69.5±4.5 years) who underwent unilateral PBC were studied before, 1 month, 6 months and 12 months after surgery by means of: (1) motor evoked potentials (MEPs) of the masseter muscle elicited by transcranial magnetic stimulation of the contralateral motor cortex and of the ipsilateral trigeminal motor branch; and (2) concentric needle electromyography of masseter muscle.

RESULTS

The latencies of MEPs' to cortical and nerve stimulation became significantly prolonged 1 month after PBC, whereas, thereafter, they demonstrated a gradual shortening towards preoperative values. The interference electromyographic pattern 1 month post-PBC study was reduced in all patients, but it improved in follow-up, returning 12-months postoperatively to complete in 13 and nearly complete in two patients.

CONCLUSION

Masseter muscle weakness should be expected in all cases after PBC of the trigeminal ganglion.

SIGNIFICANCE

As verified by repeated studies, the results of which favoured a focal demyelination process of trigeminal motor branch, muscle dysfunction appears to be reversible over a period of 6-12 months.