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Objective: Before commonly used targets such as the Retrogasserian Zone (RGZ) and the Root Entry Zone (REZ) were adopted for the radiosurgical treatment of trigeminal neuralgia (TN), a more anterior target involving the Gasserian ganglion was used. Thanks to advancements in imaging technology, it is now possible to identify and target separate nerve divisions in Meckel's Cave as desired. Although this approach has been mentioned previously, no clinical study has investigated it until now. This study aims to fill this gap in the literature., Methods: Trigeminal neuralgia patients who received radiosurgical treatment between February 2019 and June 2022 in a single centre were included in the study. Pain relief, medication dependency and side effect profiles of the investigated anterior selective target (AST) were compared to those of the classical targets at 1 week, 1-3-6 months, and 1 year., Results: A total of 66 patients were included in the study. Effectiveness, safety and application convenience parameters were compared between; the REZ (n = 21), RGZ (n = 20) and AST (n = 25) groups. All groups showed significant improvement in pain with similar results to each other. AST treatments were performed in significantly shorter beam-on-times and with significantly lower brainstem doses., Conclusions: The investigated AST showed comparable results to the classical targets without any indication of superiority or inferiority in terms of efficacy and safety in this preliminary investigation. As no blocks were needed to protect the brainstem with this method, it can be used for select patients as needed and could even be investigated in larger studies as an alternative approach., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Background: Percutaneous rhizotomy of the Gasserian ganglion is a well-established intervention for patients suffering from refractory trigeminal pain, not amenable to pharmacological management or microvascular decompression. Traditionally conducted under fluoroscopic guidance using Hartel's technique, this study investigates a modified approach employing low-dose CT guidance to achieve maximal procedural precision and safety with the emphasis on minimizing radiation exposure., Methods: A retrospective analysis of patients undergoing percutaneous rhizotomy of the Gasserian ganglion at our institution was undertaken. Procedures were divided into fluoroscopy and CT-guided foramen ovale (FO) cannulation cohorts. Radiation doses were assessed, excluding cases with incomplete data. The study included 32 procedures in the fluoroscopy group and 30 in the CT group., Results: In the CT-guided group, the median effective dose was 0.21 mSv. The median number of CT scans per procedure was 4.5, and the median procedure time was 15 min. Successful FO cannulation was achieved in all 30 procedures (100%). In the fluoroscopy group, the median effective dose was 0.022 mSv, and the median procedure time was 15 min. Cannulation of FO was successful in 31 of 32 procedures (96.9%). The only complications in the CT-guided group were three minor cheek hematomas. Immediate pain relief in the CT-guided group was reported in 25 of 30 procedures (83.3%), 22 of 30 (73.3%) provided relief at one month, and 10 of 18 (55.6%) procedures resulting in pain relief at one month continued to provide relief after two years., Conclusion: Low-dose CT-guided percutaneous rhizotomy conducted in the radiology suite carries negligible radiation exposure for patients and eliminates it for personnel. This method is fast, simple, precise, and carries a very low risk of complications., Competing Interests: Declarations. Ethical approval: All procedures performed in studies involving human participants were in accordance with the ethical standards of the University Hospital Pilsen and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Background: Surgical treatment for trigeminal neuralgia includes percutaneous techniques, including balloon compression, first described in 1983 by Mullan and Lichtor (J Neurosurg 59(6):1007-1012, 6)., Method: Here we present a safe and simple navigation-assisted percutaneous technique for balloon compression, which can also be used for glycerol injection., Conclusion: The navigation-assisted percutaneous technique for balloon compression for trigeminal neuralgia is a quick and safe treatment for patients not candidates for microvascular decompression., (© 2024. The Author(s).)

Based on a personal experience of 4200 surgeries, radiofrequency thermocoagulation is useful lesional treatment for those trigeminal neuralgias (TNs) not amenable to microvascular decompression (idiopathic or secondary TNs). Introduced through the foramen ovale, behind the trigemnial ganglion in the triangular plexus, the needle is navigated by radiology and neurophysiological testing to target the retrogasserian fibers corresponding to the trigger zone. Heating to 55-75 °C can achieve hypoesthesia without anaesthesia dolorosa if properly controlled. Depth of anaesthesia varies dynamically sedation for cannulation and lesioning, and awareness during neurophysiologic navigation. Proper technique ensures long-lasting results in more than 75% of patients., (© 2024. The Author(s).)

Varicella zoster is found exclusively in humans. Infected people with this virus result in chickenpox followed by dormant virus within neural ganglia. This dormant virus, once activated, may affect any ganglia or nerves of the body but most commonly involves the thoracic, cervical and trigeminal nerves in decreasing order of frequency. We review three such cases in which manipulation of the trigeminal ganglion resulted in reactivation of varicella at homologous operative sites. Each patient underwent surgeries in which the trigeminal ganglion was manipulated for the resection of trigeminal schwannoma under a microscope through various approaches. All three patients developed reactivation of varicella at homologous operative sites. A thorough history of chickenpox infection should be taken in patients who are undergoing surgeries for trigeminal pathology. Early diagnosis should be made once any vesicular lesions are seen with prompt treatment. Reassurance and counselling are necessary in these patients. If possible, prophylaxis may be started in all such patients. Further studies are warranted to determine the exact cause of reactivation., (© 2023. The Author(s) under exclusive licence to The Journal of NeuroVirology, Inc.)

Background: Surgical treatments for trigeminal neuralgia may include percutaneous techniques including the balloon compression technique. We present here a simple, effective, and safe adaptation of the historical technique described by Mullan in 1978., Method: Our procedure is performed in a bi-plane neuro-radiology room. During general anesthesia, 14-G needle is guided under radioscopy to foramen ovale. The 3-F embolectomy catheter is then inserted and inflated with contrast for a period of 2 min 15 s., Conclusion: Our technique, performed entirely under bi-plane fluoroscopy, allows a quicker and more precise surgery and avoids errors in guiding the catheter that can result serious injury., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Background: Trigeminal neuralgia is the most common example of craniofacial neuralgia. Its etiology is unknown and is characterized by severe episodes of paroxysmal pain. The trigeminal ganglion and its adjacent anatomical structures have a complex anatomy. The foramen ovale is of great importance during surgical procedures such as percutaneous trigeminal rhizotomy for trigeminal neuralgia., Objective: We aimed to identify the anatomical structures associated with the trigeminal ganglion and radiofrequency rhizotomy on cadavers and investigate their relationship with the electrodes used during rhizotomy to determine the contribution of the electrode diameter and length to the effectiveness of the lesion formation on the ganglion., Methods: Five fresh-frozen cadaver heads injected with red silicone/latex were used. A percutaneous puncture was made by inserting of a cannula through the foramen ovale to create a pathway for electrodes. The relationships between the electrodes, Meckel's cave, trigeminal ganglion, and neurovascular structures were observed and morphometric measurements were obtained using a digital caliper., Results: Trigeminal ganglion, therefore the electrode in its final position, shows proximity with important anatomical structures. The electrode was inserted posteriorly into the foramen ovale in all of the specimens and was located on the retrogasserian fibers. This study revealed that the electrodes targeting the ganglion and passing through the foramen ovale may cause a radiofrequency lesion due to the contact effect of the dura itself pressing on the electrode. Pushing the cannula beyond the petroclival angle may result in puncturing of the dura propria and moving further away from the target area., Conclusion: The success of radiofrequency rhizotomy is directly related to the area affected by the lesion. Understanding the mechanism of action underlying this procedure will ensure the effectiveness, success, and sustainability of the treatment., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Background: Radiofrequency thermocoagulation trigeminal rhizotomy (RT-TR) through the foramen ovale is a minimally invasive treatment for trigeminal neuralgia. Navigation of magnetic resonance imaging (MRI) and CT fusion imaging is a well-established method for cannulation of the Gasserian ganglion. In this study, we use the inline measurements from fusion image to analyze the anatomical parameters between the actual and simulation trajectories and compare the short- and intermediate-term outcomes according to determinable factors., Methods: The study included thirty-six idiopathic neuralgia patients who had undergone RT-TR with MRI and CT fusion image as a primary modality or repeated procedures., Results: Among thirty-six treated patients, the inline length of the trigeminal cistern was longer for the simulated trajectory (8.4 ± 2.4 versus 6.5 ± 2.8 mm; p < 0.05), and the predominant structure at risk extrapolated from the inline trajectory was the brainstem, which signified a more medially directed route, in contrast with the equal weighting of temporal lobe and brainstem for the actual trajectory. The preoperative visual analogue scale (VAS) was 9.3 ± 1.0, which decreased to 2.5 ± 2.6 and 2.9 ± 3.1 at first (mean, 3 months) and second (mean, 14 months) postoperative follow-up, respectively. The postoperative VAS scores at the two follow-ups were not statistically significant without a covariate analysis. After adjustment for covariate risk factors, the second follow-up sustained therapeutic benefit was evident in patients with no prior history of related treatment, an ablation temperature greater than 70 °C, and needle location within or adjacent to the trigeminal cistern., Conclusions: This preliminary study demonstrated that the needle location between cistern and ganglion also plays a significant role in better intermediate-term results., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Background: Persistent idiopathic facial pain (PIFP) is a debilitating chronic pain condition with pain radiating to trigeminal dermatomes. Typically, there are no pathological findings that can be identified during workup and therapy is symptomatic. Facial pain is common in patients with multiple sclerosis (central neuropathic pain attributed to MS). Our aim was to evaluate the effectiveness of percutaneous radiofrequency thermocoagulation (PRTC) of the gasserian ganglion and the duration of pain relief, as well as the identification of factors associated with its outcome., Methods: Data on all the above-mentioned patients that have been treated with PRTC between 2009 and 2019 were included into the study. The outcome was assessed with a six-tiered score from 1 (complete remission) to 6 (no benefit). Univariate and multivariate analyses were performed in order to obtain factors associated with the outcome., Results: A total of 52 patients were included. The total number of procedures performed was 114. 61.5% of patients who experienced temporary pain relief that lasted for a median of 60 days (range 3-1490 days). In patients with recurrence, the fraction of successful interventions was higher, and also transient, with successful pain amelioration in over 80% of patients. Successful responses to PRTC were observed in 27.9% after 1 year, 19.4% after 2 years, and 8.3% after 3 years. The only independent variable predicting pain relief was a repeat intervention with a history of ≥ 2 interventions (OR: 4.36, 95%-CI: 1.34-14.34, p = 0.015). No severe complications occurred., Conclusions: Our data showed good and immediate pain relief after PRTC in the majority of our patients. PRTC is a low-risk procedure that can be discussed as an option in case of failure of medical treatment even in critically ill patients and can be repeated with good results when necessary. Long-term pain amelioration, even with repeated procedures, was not possible and no patient was permanently cured.

Background: Several techniques have been described for the percutaneous treatment of trigeminal neuralgia; however, each has significant drawbacks. We propose a new technique for percutaneous balloon compression of the trigeminal ganglion and distal trigeminal nerve using electromagnetic (EM) neuronavigation., Methods: The procedure was performed in 17 consecutive patients with trigeminal neuralgia. Patients were then followed up with telephone interview. We also performed a cadaveric validation study to further investigate the accuracy of the technique using dye., Results: Excellent clinical outcomes were achieved with a reduction in the median pain score from 10 out of 10 to 0 out of 10 following the procedure. The cadaveric study also demonstrated a high rate of foramen ovale cannulation., Conclusion: EM-based targeting of the foramen ovale and balloon inflation within Meckel's cave is a quick, reproducible and straightforward technique for the percutaneous treatment of 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.

Background: Tumors of the middle fossa or cavernous sinus (CS), or intraorbital tumors, can penetrate each other through the superior orbital fissure (SOF) or neighboring tissue. These complicated pathologies are often treated with highly invasive surgical procedures. In this article, we demonstrate surgical anatomic dissections of the CS, SOF, orbital apex (OA), and dura mater extending to the periorbita from the middle fossa, by performing an epidural dissection via a lateral orbitotomy approach, and discuss findings that may provide guidance during surgery in these regions., Methods: Lateral orbitotomy was performed on latex-injected cadaver heads by making a 2-cm skin incision lateral to the lateral canthus, drilling the lesser and greater sphenoid wings that form the SOF borders, and removing the bone section between the middle fossa and orbit. Dura mater from the middle fossa to the periorbita was exposed to perform anterior clinoidectomy. Meningeal dura was dissected from the endosteal dura, which forms the lateral wall of the CS, to expose the CS, SOF, and OA for dissections., Results: Changing the orientation of the microscope from posterior to anterior enabled regional control for dissection from the Gasserian ganglion to the OA. Cranial nerves that pass through the CS, SOF, and OA were dissected and exposed. The annular tendon was opened, revealing the oculomotor nerves and its branches, as well as the abducens and nasociliary nerves, which pass through the oculomotor foramen and course within the OA and orbit., Conclusions: This approach causes less tissue damage; provides control of the surgical area in spheno-orbital tumors invading the fissure and foramen by changing the orientation of the microscope toward the orbit, OA, SOF, CS, and middle fossa; and expands the indication criteria for lateral orbitotomy surgery. This approach, therefore, represents an alternative surgical method for excising complicated tumors in these regions.

Introduction: Facial pain is often debilitating and can be characterized by a sharp, stabbing, burning, aching, and dysesthetic sensation. Specifically, trigeminal neuropathic pain (TNP), anesthesia dolorosa, and persistent idiopathic facial pain (PIFP) are difficult diseases to treat, can be quite debilitating and an effective, enduring treatment remains elusive., Methods: We retrospectively reviewed our early experience with stimulation involving the trigeminal and sphenopalatine ganglion stimulation for TNP, anesthesia dolorosa, and PIFP between 2010-2014 to assess the feasibility of implanting at these ganglionic sites. Seven patients received either trigeminal and/or sphenopalatine ganglion stimulation with or without peripheral nerve stimulation, having failed multiple alternative modalities of treatment. The treatments were tailored on the physical location of pain to ensure regional coverage with the stimulation., Results: Fluoroscopy or frameless stereotaxy was utilized to place the sphenopalatine and/or trigeminal ganglion stimulator. All patients were initially trialed before implantation. Trial leads implanted in the pterygopalatine fossa near the sphenopalatine ganglion were implanted via transpterygoid (lateral-medial, infrazygomatic) approach. Trial leads were implanted in the trigeminal ganglion via percutaneous Hartel approach, all of which resulted in masseter contraction. Patients who developed clinically significant pain improvement underwent implantation. The trigeminal ganglion stimulation permanent implants involved placing a grid electrode over Meckel's cave via subtemporal craniotomy, which offered a greater ability to stimulate subdivisions of the trigeminal nerve, without muscular (V3) side effects. Two of the seven overall patients did not respond well to the trial and were not implanted. Five patients reported pain relief with up to 24-month follow-up. Several of the sphenopalatine ganglion stimulation patients had pain relief without any paresthesias. There were no electrode migrations or post-surgical complications., Conclusions: Refractory facial pain may respond positively to ganglionic forms of stimulation. It appears safe and durable to implant electrodes in the pterygopalatine fossa via a lateral transpterygoid approach. Also, implantation of an electrode grid overlying Meckel's cave appears to be a feasible alternative to the Hartel approach. Further investigation is needed to evaluate the usefulness of these approaches for various facial pain conditions.

Purpose: Puncture of the ganglion Gasseri through the foramen ovale and subsequent thermocoagulation, balloon compression, or glycerin injection is a well-established technique to treat trigeminal neuralgia. However, direct puncture of the foramen is sometimes difficult. Here, the authors present a simple technique of improved biplane fluoroscopic control for insertion of the needle into the foramen ovale., Methods: The authors evaluated an alternative oblique X-ray trajectory for the correct placement of a needle into the foramen ovale on cadaveric skull models. After determination of the ideal X-ray trajectory, 13 subsequent patients suffering from trigeminal neuralgia were subjected to intraforaminal needle placement with application of the alternative X-ray trajectory., Results: An oblique projection with the X-ray tube (mean rotation 20.9° and angulations 28°) aligned coaxially to the inserted needle is proposed. On cadaver skull models, this oblique trajectory appeared to be ideal for visualization of the correct needle position. In the 13 patients, an immediate needle insertion into the foramen ovale was achieved under this direct oblique fluoroscopic control. No complications were observed., Conclusions: Experimentally and clinically, the new projection demonstrated three distinct advantages over the standard submental projection: Firstly, the foramen ovale can be better visualized independent of the patient's position. Secondly, needle correction or insertion can be performed much easier because of the direct fluoroscopic control. Thirdly, the correct needle position in the foramen ovale is more reliably determined than with the submental projection due to projection geometry. Further studies are needed to give evidence that the needle insertion into the foramen ovale is easier achieved with the coaxial projection than with the standard technique.

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.

Background: We performed a comparative study of the retrogasserian zone (RGZ) with the dorsal root entry zone (DREZ) target to determine effective gamma knife radiosurgery (GKRS) technique in patients with medically refractory trigeminal neuralgia (TN)., Methods: We retrospectively reviewed the records of 39 patients with refractory TN undergoing GKRS between April 2005 and October 2008. Until October 2007, DREZ was used as the primary target point. Since November 2007, RGZ has been targeted, located anterior to DREZ. The pain outcome of patient, pain recurrence, and treatment-related complications were evaluated., Findings: Using the Barrow Neurologic Index (BNI) pain score, 15 (93.8%) RGZ and 20 (87.0%) DREZ cases achieved treatment success (BNI pain score I-IIIb) (p = 0.631). Seven (43.8%) RGZ and four (17.4%) DREZ patients reported complete pain relief without medications (BNI pain score I). The time to a response after the GKRS was significantly shorter in the RGZ group (mean 4.1 weeks) than in the DREZ group (mean 6.4 weeks) (p = 0.044). The total complication rate (25.0%) in the RGZ group was similar to the DREZ group (26.1%); however, frequency of bothersome facial numbness and dry eye syndrome was lower in the RGZ group (0%, 0%) compared to the DREZ group (13.1%, 8.7%) (p = 0.255 and 0.503)., Conclusions: The RGZ targeting technique in the GKRS for TN had a better treatment success, with fewer bothersome complications compared to the DREZ target.

Background: Trigeminal neuralgia is a common cause of facial pain, characterized by shock-like pain affecting one or more branches of the trigeminal nerve. When conservative treatment fails and microdecompression is not indicated, percutaneous procedures are helpful. This percutaneous approach is done by a puncture up to the Gasserian ganglion, through the foramen ovale. Although simple and safe, this puncture demands some expertise from neurosurgeons. For that, a partnership between neurosurgeons and bio-engineers has developed a model for foramen ovale puncture, allowing practice for residents and young neurosurgeons., Method: A model for foramen ovale puncture has been created by interposition of synthetic materials over a skull, simulating the human face., Findings: This model has shown great similarity with that found in conventional surgeries, even upon repeated testing by experienced functional neurosurgeons and young residents., Conclusion: This model for foramen ovale puncture training has demonstrated valuable help for initial practicing of this common neurosurgical procedure, particularly in centers where there are not many cadavers available for training.

The petrolingual ligament is the posteroinferior attachment of the lateral wall of the cavernous sinus, where the internal carotid artery enters the cavernous sinus. The petrous segment of the internal carotid artery finishes and the cavernous segment begins at the superior margin of this ligament. The ligament is surgically important due to its identification as a landmark for dissection of the internal carotid artery during the approaches to posterolateral intracavernous and extracavernous lesions. It can be well exposed after mobilization of the gasserian ganglion, or after the trigeminal root and ganglion have been split along the junction of V2 and V3 (the transtrigeminal approach). The petrolingual ligament was studied in five cadaveric head specimens from ten sides. The size of the ligament was measured, and its anatomical, clinical and surgical importance is discussed.

The blink reflex was prospectively studied in 28 patients with trigeminal neuralgia, prior-to and following percutaneous glycerol rhizotomy to the Gasserian ganglion. Fifteen patients (54%) had varying degrees of sensory loss in the trigeminal nerve distribution already before glycerol injection. Three more patients developed sensory loss following glycerol injection. Thus following glycerol injection 18 patients had graded sensory loss. Pre-injection the blink reflex showed abnormal R1 wave in 57% patients, while direct and consensual R2 waves were abnormal in 43% and 48%, respectively. Post-injection R1 wave was abnormal in 64% patients. Direct R2 waves were abnormal in 33% patients. Thus clinical findings of sensory loss correlated well with pre-and post-injection blink reflex abnormality. Postoperatively R1 and ipsilateral R2 latencies from the side of the injection deteriorated and consensual R2 latency improved, thus, signifying better function on the contralateral side following relief of pain by glycerol rhizotomy.

A modified lateral subtemporal, transpetrous apex and sub-Gasserian ganglion approach was found to be most suitable for clival chordomas. The approach selection was based on the typical anatomical relationship of chordomas in terms of site of origin, pattern of growth and neural and vascular displacements. The approach was suitable to deal with tumour anterior and lateral to the brain stem, the clival part of the tumour and its sub-cavernous sinus extensions. The carotid artery was under control. The approach had the advantage of being simple and relatively quick and of its familiarity to general neurosurgeons. The tumour could be excised radically and extension of anterior, posterior and inferior exposure was possible.

From 1980 through 1993 a series of 44 patients with trigeminal neurinomas was treated. Five of them were operated on for the remainder of the tumour as they had undergone previous surgery elsewhere, 35 were operated on for the first time, and 4 were not operated on for various reasons. An epidural approach to the neurinomas originating in the branches of the Vth nerve peripherally to the Gasserian ganglion (GG) was used. In the neurinomas originating in the GG or in the root of the Vth nerve, either an epidural-transdural approach or an epidural-transdural-transpetrous approach was used. All tumours operated on using the approach described in this article were completely removed. In 10 patients, the Vth nerve sensory deficits increased in comparison with preoperative deficits; in 9 their state remained unaltered; and in 11 the sensory function of the Vth nerve improved. In those patients who had experienced pre-operative atypical trigeminal pain, the pain disappeared after surgery. There was no additional treatment: radiosurgery, irradiation or chemotherapy. Histopathological examination did not reveal any malignant changes in the tumours in any of the patients. Based on our own experience and on the published data it is believed that the best treatment for trigeminal neurinomas is complete microsurgical removal of the lesion.

Neoplastic involvement of the trigeminal nerve was observed in 73 patients operated on in our institution for extra-axial tumours of the posterior and middle cranial fossae. It was defined as contact, compression, or infiltration. The nerve root was involved in 58 patients, the ganglion and/or the peripheral divisions in 9, all portions of the Vth nerve system in 6. A clinical trigeminal dysfunction was present in 44 patients (60%). Anatomico-surgical findings are correlated with clinical features and with tumour type. Typical trigeminal neuralgia was the complaint in 7 subjects; all of them presented an involvement of the sensory root. Post-operatively, 11 patients were relieved of their symptoms. The outcome is correlated with the anatomical findings and with the extent of surgical removal of the tumours. The importance of a careful evaluation of patients with trigeminal symptomatology is stressed.

Four hundred and seventy five patients with trigeminal neuralgia underwent cryotherapy (145), radiofrequency thermocoagulation (265) or microvascular decompression 65) and were then followed up for mean time of 45 months. Outcome of treatment was assessed not only by the clinicians but also by a postal questionnaire. The presence of anxiety and depression was determined and compared to 51 patients due to undergo surgery. The median time to recurrence for the cryotherapy patients and the radiofrequency thermocoagulation patients were 6 and 24 months, respectively. At 5 years 38% of the microvascular decompression patients had had a recurrence of neuralgia. There was one operative death in the radiofrequency thermocoagulation group. Patients in all three groups were satisfied with their treatment but the questionnaires showed that clinicians under-report the recurrence of pain and post operative complications. Pre-operatively depression and anxiety are high but post-operatively only 15% were depressed. Patients need careful pre-operative assessment which includes the McGill Pain Questionnaire and they should be given a choice about which surgical method would be most suitable in their case. Printed information should be available to supplement the consultation. This would ensure the patients' expectations matched up with the results as they would be aware of possible outcomes.

Analysis of verbal responses to electrical stimulation of the trigeminal ganglion and rootlets has been the only method available so far to localize the electrode tip in the most appropriate trigeminal division or division segment, prior to thermocoagulation during percutaneous treatment for trigeminal neuralgia. A diversity of factors may lead to unreliable verbal responses, resulting in increased morbidity or even therapeutic failure. In an attempt to enhance the accuracy of electrode localization during Sweet's procedure, we describe an electrophysiological method complementary to clinical responses. Sensory trigeminal evoked potentials (STEPs) induced by separate successive orthodromic cutaneous stimulation of the three trigeminal divisions and recorded by the isolated tip of a transoval thermocouple electrode, together with motor trigeminal evoked potentials (MTEPs) elicited by stimulation of the trigeminal ganglion and recorded in the ipsilateral temporal muscle, were sequentially examined in six patients undergoing percutaneous tic treatment during gradual rostro-caudal electrode withdrawal. STEPs and MTEPs showed appropriate correlation with verbal and clinical motor responses at each electrode site. General anaesthesia failed to affect STEPs. Systematic exploration in the awake patient of both verbal and clinical motor responses, together with STEPs and MTEPs, is therefore recommended prior to the induction of radiofrequency lesions in the course of percutaneous treatment for trigeminal neuralgia.

The authors report on indications and results of percutaneous surgical treatment of trigeminal neuralgia based on own experiences in 1124 cases. In 912 cases percutaneous thermorhizotomy and in 212 cases percutaneous microcompression have been used. As a conclusion the following considerations have been stressed: I) In both methods slight hypaesthesia appears to obtain good pain relief; II) Percutaneous thermorhizotomy is indicated in third division neuralgias; III) Percutaneous microcompression is indicated for first and second division neuralgias only when the trigeminal cistern is not abnormally dilated; IV) Undesirable side-effects after either thermorhizotomy and microcompression are similar and transitory in most cases; V) Pain recurrence for both procedures are comparable and range at about 25%.

Facilitation of the opiate-mediated system provides relief of excess pain but not of deafferentation pain. Influence on neuronal hyper-activity, which was provoked after the deafferentation of the peripheral trigeminal nerve (deafferentation hyperactivity; DH), by stimulation of the internal capsule (IC), VPM nucleus of the thalamus and by the cerebral sensorimotor cortex, was examined. This experiment demonstrates that a suppressive effect is exerted on the sustained neuronal hyperactivity, which was proved to have a close relationship with deafferentation pain. In the preliminary experiment, it was confirmed that DH was provoked by coagulation of unilateral (left side) Gasserian ganglion in 29 adult cats, who were allowed to survive up to 72 days. DH, sustained high amplitude discharge without any stimuli on the face or neck, was detected in the subnucleus caudalis of the spinal trigeminal nucleus (STNcd) of the denervated side. DH was never suppressed by facilitation of the opiate-mediated system. 87 of 113 neurones identified in the STNcd of the denervated side showed DH in another 18 cats. In 30 of 55 neurones examined, DH was conspicuously suppressed by the stimulation of contralateral (right) side, 11 of 29 neurones by ipsilateral IC. Five of 13 neurones were suppressed by contralateral VPM stimulation, 2 of 3 neurones by ipsilateral stimulation. Stimulation of cortical area, SM1 of MS1, in other 15 cats, considerably suppressed DH in STNcd. Microinjection of wheat-germ-agglutinin in the cerebral cortex revealed in direct projection of the descending fibre from MS1 to STNcd and brain stem reticular formation via IC.(ABSTRACT TRUNCATED AT 250 WORDS)

The effectiveness of percutaneous microcompression of the gasserian ganglion, performed according to the technique proposed by Mullan and Lichtor, was evaluated in 74 patients affected by essential trigeminal neuralgia and compared to the results obtained with the RF thermocoagulation of Sweet and Wepsic. Similar results were obtained with the two methods but adverse side-effects were less common with microcompression. It is concluded that the microcompression should be recommended as a first choice among the different percutaneous procedures in the treatment of trigeminal neuralgia.

Percutaneous radiofrequency lesion of the Gasserian ganglion was performed between 1974 and 1984 in ninety-eight patients for the relief of trigeminal neuralgia. The average follow-up period was 4.5 years. Age, sex, and duration of illness were unrelated to outcome. Satisfactory analgesia was achieved in 68 patients. Thirty-one percent had return of pain (30 cases). Recurrent neuralgia occurred most frequently during first postoperative year (46%). Patients with marked sensory deficits had a reduced risk of recurrence. Postoperative complications included: reduced or absent corneal reflex (18 cases), corneal keratitis (3 cases) and anesthesia dolorosa (2 cases).