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Background: Magnetic resonance imaging (MRI) has been widely used for visualizing trigeminal nerves in trigeminal neuralgia., Objective: To assess atrophy and diffusion abnormalities of affected trigeminal nerves in trigeminal neuralgia with 7-T MRI., Methods: In this prospective study, 14 patients (mean age 49 years; range 31-64 years) with trigeminal neuralgia underwent 7-T MRI. We measured trigeminal nerve volumes along their course through the pontocerebellar cistern. We also evaluated fractional anisotropy (FA) and quantitative anisotropy (QA) values within cisternal segment and pontine nuclei of the affected-side and unaffected-side trigeminal nerves, using diffusion tensor imaging (DTI). Associations between DTI metrics and Barrow Neurological Institute (BNI) pain scores were examined., Results: The volumes were significantly smaller for the affected trigeminal nerves (33.83 ± 23.12 mm3) than for the unaffected ones (47.76 ± 32.48 mm3; p = 0.008). Cisternal segment FA and QA values were significantly lower in affected trigeminal nerves than in unaffected ones. However, DTI measurements in the pontine nuclei revealed no significant differences between affected-side and unaffected-side trigeminal nerves. No DTI metrics significantly correlated with BNI pain scores., Conclusion: Our results suggest that 7-T MRI allows identifications of atrophy and diffusion abnormalities of trigeminal nerves in trigeminal neuralgia., (© 2019 S. Karger AG, Basel.)

Aims: To investigate the long-term outcomes of repeated percutaneous radiofrequency thermocoagulation (PRT) for recurrent trigeminal neuralgia (TN) patients., Methods: Between 2002 and 2012, 33 patients with recurrent TN following an initial PRT procedure were retrospectively studied and underwent 43 repeated PRT procedures., Results: The mean length of follow-up after repeated PRT was 34 months. Pain relief was immediate in 30 patients (90.9%), and no pain relief occurred in 3 patients (9.1%) following a second PRT procedure. The percentage of patients who remained in an 'excellent' and 'good' pain relief condition (pain intensity ≤BIN grade III) after the second PRT procedure was 75% at 1 year, 68% at 2 years and 68% at 5 years, and 22 of these patients (54.5%) remained satisfied with their pain relief during the follow-up period. Nine patients underwent PRT three times and 1 patient four times. The total number of patients who benefited from repeated PRT was 28 (84.8%). Postprocedure complications including masseter weakness were present in 3 patients and limited mouth opening affected 1 patient. No mortalities were observed during or after repeated PRT procedures., Conclusion: Repeated PRT provides long-term pain relief benefits to patients with recurrent TN and should be considered as an alternative treatment for recurrent TN., (© 2014 S. Karger AG, Basel.)

Aims: Trigeminal neuropathic pain is a broad diagnostic category that includes pain of several etiologies and excludes trigeminal neuralgia. The authors report a prospective series of percutaneous gasserian ganglion stimulation for trigeminal neuropathic pain., Methods: Patients who experienced >50% reduction in pain from a 7- to 10-day trial period underwent permanent implantation and were prospectively followed., Results: Eight of 10 trialed patients received a permanent implant. At the 12-month follow-up, 2 patients had been explanted and 1 was lost to follow-up. Three (all working at that the time) continued to experience >50% improvement in pain., Discussion: The results in this series were variable but 3 patients showed long-term improvements. Patients who continued to work responded better to treatment., (Copyright (c) 2007 S. Karger AG, Basel.)

Background: Patients with typical trigeminal neuralgia were treated by one neurosurgeon with either microvascular decompression (MVD) or Gamma Knife radiosurgery (GKRS) and were prospectively evaluated with a uniform protocol., Method: GKRS was done with 75 Gy maximum to the cisternal trigeminal nerve near the pons. MVD was done without cauterizing or cutting the trigeminal nerve., Results: Twenty-four patients were treated with MVD and 61 with GKRS. Complete pain relief (no pain no medicines) occurred at 12 and 18 months in 68 and 68% of patients treated with MVD and 58 and 24% with GKRS (p = 0.089), and >or=90% pain relief (with or without medicine) at 12 and 18 months in 90 and 78% with MVD and 75 and 48% with GKRS (p = 0.171). There were no permanent complications., Conclusion: Although many trigeminal neuralgia patients treated with either MVD or GKRS have pain relief, MVD is more likely than GKRS to result in complete pain relief., (Copyright (c) 2007 S. Karger AG, Basel.)

Most trigeminal neuralgia (TN) studies focus on a single strategy, microvascular decompression (MVD) or percutaneous rhizotomy (PR). We use a multimodality approach to TN. We perform MVD on patients younger than 70 years and PR on older patients or those where MVD has failed. We performed a chart review of the procedures for TN over the past 3 years and used a questionnaire for long-term follow-up. The questionnaire asked patients to rate their pre- and postoperative pain, outcome, and medication changes. Seventy-four procedures (40 MVDs and 34 PRs) were performed on 67 patients. Twenty patients had undergone previous procedures. 93% of the patients had significant initial pain relief. Over a 1.2-year mean follow-up, 51% of the patients had complete pain relief while 27% had a substantial improvement. There were no deaths and 5 complications. Our results suggest that a multimodality approach to TN yields excellent results with minimal complications., (2005 S. Karger AG, Basel.)

Purpose: Gamma knife (GK) radiosurgery for trigeminal neuralgia (TN) has been effective in 50-80% of cases when using a single 4-mm collimator and a maximum dose of 60-90 Gy. Attempting to improve the response rate by increasing the dose may lead to increased risk of facial numbness or disturbed sensation. Combined use of 4- and 8-mm collimators results in a larger target volume, which would potentially treat a larger region of the nerve without increasing the maximum dose., Materials and Methods: One hundred-one patients suffering from medically refractory TN were evaluated. Fifty-four were treated with a single shot using a 4-mm helmet and 47 with concentrically aimed, equally weighted 4- and 8-mm helmets. 75 Gy were prescribed to the 100% isodose line (using a 4-mm helmet output factor of 0.80) in all cases. The outcome was assessed by interview or outpatient visit., Results: An excellent/good response was seen in 57.8 vs. 71.4%, respectively, with a partial response of 13.3 vs. 2.3%, respectively (p > 0.05). Pain recurrence occurred in 28.6 vs. 23.2%, respectively (p > 0.05)., Conclusion: The use of a combined concentric 4- and 8-mm collimator treatment for medically refractory TN at a maximum dose of 75 Gy does not improve outcome as compared with a single 4-mm collimator with an equivalent maximum dose., (Copyright 2004 S. Karger AG, Basel)

This paper deals with the first 45 consecutive patients undergoing microvascular decompression (MVD) surgery for trigeminal neuralgia, studied with perioperative brainstem auditory evoked potentials (BAEPs) and electromyography (EMG). We observed a good correlation between the intraoperative BAEP modifications and postoperative hearing function. BAEP monitoring was useful in identifying the manoeuvres that may compromise cochlear nerve function. This improved the surgical technique in the subsequent cases and reduced the incidence of iatrogenic hearing deficits after the learning period. There were no correlations between the entity of the intraoperative EMG discharges and the postoperative facial and trigeminal function. Intraoperative EMG monitoring can be useful during the period of learning as a means of identifying the different nerves in the cisternal tract.

While most of the studies examining radiosurgery for trigeminal neuralgia have used a Gamma Knife, a linear accelerator can also be utilized for treatment. We report on 20 patients with trigeminal neuralgia who received 23 treatments with a linear accelerator that delivered a maximum dose of 82.3-100 Gy. The median patient follow-up was 56.5 months, 70% of patients had received previous surgical treatment and 20% had secondary (nonessential) trigeminal neuralgia. Eight (35%) radiosurgery treatments resulted in complete pain relief; 5 (63%) patients with initial pain relief had pain recurrence at a mean time of 21.5 months. Ten (43%) patients reported a 50% or more decrease in pain severity but have not achieved a pain-free state. A total of 18 (78%) treatments resulted in no pain or a 50% or greater improvement in pain. Five treatments (22%) resulted in less than 50% improvement in pain. We conclude that linear accelerator stereotactic radiosurgery is a viable treatment option for trigeminal neuralgia patients, especially for patients who have not had a previous invasive treatment.

Objective: Previous papers have reported Gamma Knife radiosurgery to be a safe, effective method for primary trigeminal neuralgia. Since November 1996, we have treated primary trigeminal neuralgia using the Leksell Gamma Knife at the Tianjin Medical University. The present study reports clinical results of Gamma Knife radiosurgery in the treatment of trigeminal neuralgia in 80 cases., Methods: The mean patient age was 67 years (range 32-92), the mean duration of facial pain was 7.6 years (range 1.5-29). The male:female ratio was 31:49. The right side of the face was involved in 45 patients (56.25%) and the left side in 30 cases (37.5%), with bilateral involvement in 5 cases (6.25%). Under local anesthesia, all patients underwent stereotactic MRI to identify the trigeminal nerve. A single isocenter, using a 4-mm collimator, was positioned at the sensory root of the trigeminal nerve entry zone of the pons, 4-6 mm from the brainstem surface, so that no more than the 20% isodose was administered to the brainstem. The maximum dose was between 70 and 90 Gy, with a mean of 75.6 Gy. For bilateral trigeminal neuralgia, two separate matrices were employed, and bilateral Gamma Knife radiosurgery was performed on the same day., Results: Follow-up ranged from 12 to 43 months (mean 23.7 months). Neurological evaluation indicated excellent response in 42 cases (52.5%), good response in 25 cases (31.25%), effective response in 8 cases (10%), so the total pain control rate was 93.75%. The latency from Gamma Knife surgery to pain relief ranged from 1 to 120 days (mean 22 days). Among the 75 patients 7 with pain control experienced pain recurrence 5-26 months after being completely free from pain. A second Gamma Knife radiosurgery was performed in 7 recurrent cases and 5 patients with treatment failure. A maximal dose ranging from 70 to 80 Gy was given (mean 74.2 Gy). After a mean follow-up of 18 months (8-33 months), 9 patients achieved excellent results, and 2 had good results. The latency interval to pain relief ranged from 1 to 120 days (mean 15 days). Nine patients developed new facial numbness, while no other complication appeared in the remainder of the patients., Conclusions: Gamma Knife radiosurgery is a safe and effective method in the treatment of trigeminal neuralgia once diagnosis is established., (Copyright 2002 S. Karger AG, Basel)

Long-term follow-up data were analyzed to evaluate the surgical results of microvascular decompression (MVD). Among 1,324 patients with trigeminal neuralgia (TGN), who underwent MVD between 1976 and 2000, a consecutive 281 patients were followed and studied for 5-20 years as of the year of 1997. When the data were analyzed and compared in two groups (A: 1976-1986, B: 1987-1991), the postoperative cure rate increased from 92.9 to 96.7%, satisfaction rate with the results of MVD increased from 80.3 to 82.5%, incomplete cure rate decreased from 7.1 to 3.3%, and recurrence rate decreased from 10.2 to 6.5%. Advances in surgical techniques may have increased the success rate in Group B., (Copyright 2002 S. Karger AG, Basel)

The following study was conducted to evaluate the results of Gamma Knife stereotactic radiosurgery in the management of secondary trigeminal neuralgia. 53 patients suffering from secondary trigeminal neuralgia were studied and the results reported. We defined four therapeutic groups: group I correspond to essential trigeminal neuralgia. The primary aim was tumor control in group IV and pain cessation in group III and II (visualization of the fifth nerve root was possible in group II but not in group III). The target dose of the radiosurgery used in the current study varied from 20 to 40 Gy in group III and IV and from 70 to 90 Gy in group I and II. At short-term follow-up, 37 patients (74%) were pain-free, 9 patients (18%) were improved (50%-90% relief) and only 4 patients (8%) experienced treatment failure. Among the patients with early treatment success, 10 patients experienced a complete recurrence of pain in the four succeeding years, and 11 initially pain-free patients deteriorated to partial pain relief. The median time to pain relief was three months (range 1 day to 1 year). The mean follow-up was 32 months (range 7 to 60 months). No patient developed increased facial pain or deafferentation pain. Among the 53 patients, only two exhibit a slight facial hypesthesia and one patient described motor fasciculation related to Gamma Knife treatment. In our experience Gamma Knife surgery appears a safe and effective method for the treatment of secondary trigeminal neuralgia.

Between October 1995 and October 1996, we treated 49 patients suffering from trigeminal neuralgia with Gamma Knife radiosurgery. There were 23 males and 26 females. The mean age was 68 (range 38-94 years) The root of the trigeminal nerve close to brain stem was chosen as the target. The maximum dose was 70 Gy in 24 cases and 80 Gy in 25 cases. A single shot with the 4-mm collimator was used. 13 patients underwent Gamma Knife treatment of trigeminal nerve root without any previous surgical procedures. 31 patients suffered from an essential neuralgia (EN), while 7 had neuralgia related to multiple sclerosis (MS). Three had atypical neuralgia (AN) and 8 patients had postherpetic neuralgia (PN). Patients were divided into five groups according to pain reduction. The success rate of pain relief (excellent, very good and good responses) in these patients was: EN 77% of patients, MS 43%, AN 33% and PN 38% of patients. Pain relief occurred after latent intervals of between 1 day and 8 months (median 2 months and mean 2.8 months). Clinically detected complications after radiosurgery occurred only in the form of tactile hypesthesia in 6%. In a selected group of 18 patients, we observed slight electrophysiological changes in 2 patients (11%) after Gamma Knife treatment.

One-hundred thirty-six patients operated on for extra-axial tumors of the posterior and middle cranial fossae were retrospectively evaluated to define the relevance of trigeminal nerve dysfunction and to correlate clinical and surgical observations. The following data are reported: tumor types, presence of specific trigeminal symptoms and signs, mean duration of symptomatology, anatomical relation between tumor and fifth nerve. Trigeminal symptoms were present in 45 subjects (33.08%) with a mean duration of 23.56 months. Frequency of symptoms was different in various oncotypes. Fifth nerve disturbances were the symptom of onset in 18 subjects (13.23%). A tumoral involvement of the nerve was reported at surgery in 73 patients (53.67%) and was defined as contact, compression or infiltration. Postoperatively, 12 patients showed an improvement of fifth nerve disturbances. A statistically significant difference (p < 0.05) was found in: (1) the incidence of symptoms in patients with and in those without anatomical trigeminal involvement: (2) the incidence of signs in the same groups; (3) the incidence of postoperative relief in patients with fifth nerve compression compared to patients with different surgical findings; (4) the incidence of postoperative relief in patients with typical trigeminal neuralgia compared to those with other symptoms.

The treatment of so-called atypical trigeminal neuralgia, characterized by long-lasting burning pain sensations without any pain attacks was for a long time an unsolved problem in contrast to the so-called 'tic douloreux'. Following the experience with our own patients and other groups, destructive procedures in atypical trigeminal neuralgia frequently result in worsening of the clinical conditions. We have therefore transferred the well-established method in the periphery of therapeutic electrostimulation to the trigeminal region. The evaluation of the patients with atypical trigeminal neuralgia is the key for good therapeutic results. Therefore percutaneous test stimulation of the ganglion gasseri has to be performed during a hospital stay. 54% of 149 patients experienced pain relief during test stimulation. Therefore in 81 patients with positive test results, electrodes were implanted together with a neurological pulse generator (Itrel Medtronic).

Three patients with midbrain lesion are described who showed trigeminal sensory symptoms in the contralateral side. Two with ischemic stroke showed partial oculomotor paresis while the third with probable vascular malformation had trochlear palsy. Considering their clinical manifestations and magnetic resonance findings, their sensory changes are believed to be caused by the involvement of the crossed trigeminothalamic fibers near the ocular motor nuclei.

The changes in arterial blood pressure which occur during the different steps of thermocoagulation of the trigeminal ganglion and rootlets are reported. The arterial blood pressure of 54 patients with trigeminal neuralgia was recorded continuously by catheterization of the radial artery. The maximal values were recorded (a) during the analgesic-sedation stage; (b) when the electrode came into contact with the base of the cranium during movement of the needle towards the foramen ovale; (c) during insertion of the electrode into the foramen ovale, and (d) during the thermocoagulation. One-way analysis of variance and Student's t test were used for analysis of the data. There was a significant increase of arterial blood pressure during the various stages of thermocoagulation.

Stereotactic radiosurgery under local anesthesia with the Leksell Gamma Knife can effectively treat some patients with recurrent tic douloureux after unsuccessful medical/surgical procedures. Seven of 12 patients have shown complete relief or improvement of their trigeminal neuralgia. No complications have been observed.

Percutaneous rhizotomy, microvascular decompression or rhizotomy by suboccipital craniotomy often cures medically untreatable trigeminal neuralgia with an acceptable complication rate. However, pain involving the same trigeminal distribution persists in a few patients despite both rhizotomies. For 7 patients with such surgically 'failed' trigeminal neuralgia, we performed descending trigeminal tractotomy. In all patients, neuralgia ceased immediately postoperatively and has not recurred during 9 months to 15 years follow-up. Descending trigeminal tractotomy provides a satisfactory solution to this relatively rare but paroxysmal pain syndrome.

22 patients undergoing percutaneous microcompression of Gasserian ganglion for the treatment of trigeminal neuralgia were monitored intraoperatively by means of trigeminal evoked potentials (TEPs). The second trigeminal branch was stimulated at the maxillary foramen; evoked responses were recorded using subcutaneous electrodes placed over the scalp. TEPs presented several short-latency waves (called W1, W2, W3, P4, N5, P6, N10) which are generated before and after the ganglion (W1, W2, W3), in the brain stem (P4, N5, P6) and possibly in the cortex (N10); other waves occur within 150 ms after the stimulus (late waves). During compression, W1 did not change, while W2 and W3 as well as P4, N5, P6, N10 and late waves decreased in amplitude: this pattern was noted in the patients who presented with pain relief during the follow-up period. On the contrary, the patients who suffered from pain recurrence did not show similar intraoperative TEP changes. In conclusion, intraoperative TEP derangements may be related to the effectiveness of the compression on the Gasserian ganglion.

The possibility of obtaining a selective effect on different trigeminal branches by glycerol rhizotomy was studied in the treatment of trigeminal neuralgia. Transcutaneous electrical stimulation was used to quantify sensory impairment. An attempt was made to direct the neurotoxic effect by maintaining the patient's head in different positions during and after glycerol injection. The amount of glycerol injected varied according to the estimated size of the trigeminal cistern and/or to which branch that was involved. The study demonstrated a good selective effect on the ophthalmic branch, less selective on the maxillary, and a poorly selective effect on the mandibular branch. However, the clinical result following glycerol rhizotomy was equal regardless of the affected trigeminal branch.

Maximal conduction velocity in the supraorbital nerve (afferent fibers for the blink reflex) has been estimated in 12 normal subjects (on the right and left side): the mean value was 41 m/s. Furthermore, this investigation was made on 23 patients with different pathologies (9 with trigeminal neuralgia with hypoesthesia, 8 with multiple sclerosis, 6 with cerebellopontine angle tumor). Normal and pathological results are discussed and diagnostic prospects of this procedure evaluated.

Spinal and trigeminal dorsal root entry zone destruction (DREZ-tomy) was performed on 35 patients with deafferentation pain of various types. Overall, satisfactory pain relief was obtained in 65.5% of spinal DREZ-tomy cases in the follow-up observation. The result in the brachial plexus avulsion group was the best (82.4% improved), followed by the limb pain group without root avulsion (50.0%), but the truncal or visceral pain group showed the worst result (33.3%). Two patients with postherpetic trigeminal neuralgia were completely relieved of pain in the average follow-up period of 32 months, while in 2 patients with postrhizotomy facial pain, pain recurred 4 months after the operation in 1, and, in the other, pain in the medial part of the face remained unchanged. Complications were seen in about 60% of the patients, which were, however, all mild, except for 2 cases of death due to gastrointestinal disease.

During percutaneous thermocoagulation of the Gasserian ganglion for trigeminal pain, the pain perception threshold was established in a series of 25 awake patients by measuring the temperature at the electrode tip within the ganglion during slow increase of the radiofrequency current. Between 42 and 48 degress C pain perception was regularly reported by the patients. A cutaneous-stimulating system was then applied to the trigeminal area which was reported to be painful during the heating. The external stimulation attempted to preferentially stimulate the A afferent nerve fibres. When external stimulation was applied during the heating of the Gasserian ganglion, the pain perception threshold was enhanced in about half of the cases. A transcutaneous electrical stimulation of part of the body not related with the investigated pain sensation did not produce the same inhibitory action in 3 out of 5 cases.

Percutaneous thermocoagulation of the Gasserian ganglion allows a good preservation of facial touch sensation with a complete and immediate regression of the symptomatology in a majority of cases. Neurophysiological bases are the peculiar resistance to the thermal lesion of the large myelinated fibers compared to the relatively smaller fibers. The study of the cortical-evoked responses before and after surgery suggests that the afferent volley travels in preference along these large myelinated fibers.

Deafferentation hyperactivity, produced unilaterally in the neurons of the subnucleus caudalis of the spinal trigeminal nucleus (STNcd) in cats by left Gasserian ganglionectomy, was studied neurochemically and electrophysiologically. Analysis of neuronal activities on both sides of the STNcd was done 11-63 days after the denervation. On the denervated side, 37 (57%) of the 65 neurons identified showed deafferentation hyperactivity. Continuous and spontaneous firing of these hyperactive neurons were inhibited neither by the intraventricular administration of morphine or enkephalinamide nor by the electrical stimulation of periaqueductal gray. In contrast, the facilitation of the pain perceptive neuronal activities in the STNcd of the nondenervated side was remarkably inhibited, both by the administration of the same drugs and by periaqueductal gray stimulation. The deafferentation hyperactivity produced in this experiment in the STNcd of the denervated side might have a close physiological relationship to the deafferented pain of clinical patients.

The mechanism of denervation supersensitivity was investigated, using the pupillary system as an experimental model. A pharmacological study was carried out in six patients with Horner's syndrome due to postganglionic lesions. Administration of cocaine 4 percent resulted in dilatation of the normal pupil, while subsequent instillation of phenylephrine (2.5-5 percent) produced equal dilatation in both eyes. The results of the study indicate that denervation supersensitivity of the pupil can be explained solely by impaired reabsorption of catecholamines.