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Facial pain in the distribution of the trigeminal nerve, commonly identified as trigeminal neuralgia, should not be confused with trigeminal neuropathic pain. The latter is caused by an accidental and nonintentional nerve lesion. When the first-line pharmacological treatment fails to provide satisfactory pain relief, surgical treatment, such as microvascular decompression and neurodestructive interventions (radiofrequency or cryotherapy), is not indicated. The logical choice of technique becomes neuromodulation, but it may be challenging to perform in the facial area. Although the initial results of trigeminal ganglion stimulation were promising, they often were of short duration because of lead migration and inadequate stimulation coverage in the trigeminal nerve distribution. To ensure accurate placement and proper anchoring, a custom-made electrode was developed and produced, and its stereotactic implantation is guided by electromagnetic navigation. This technique has been used at our center for several years; the published results show at least 30% of pain relief in 75% of the patients and considerable reduction in medication use., (© 2016 S. Karger AG, Basel.)

Objective: In this paper, a technique to place a probe at the trigeminal ganglion using a stereotactic frame and intraoperative computed tomography (CT) scans is described., Method: The procedure is performed on the CT table using a stereotactic frame. After the coordinates have been obtained and then adjusted, the target is probed using the frame. In this study, intraoperative scans were obtained to confirm the accuracy of probe placement. After successful stimulation studies, radiofrequency lesions were made. Thirty-two procedures were performed on 26 patients., Results: Twenty patients were free of pain at a follow-up which lasted a median of 30 months. There was no permanent complication from the procedure., Conclusions: The technique is straightforward, accurate and safe. It also enables the surgeon to obtain intraoperative confirmation of accurate probe placement on CT images., (2010 S. Karger AG, Basel.)

Aims: The main purpose of this study is to underline the factors which are likely to increase the risk of a sixth nerve injury after percutaneous balloon compression of the gasserian ganglion., Methods: Medical records and intraoperative radiological images of 79 consecutive patients, who underwent percutaneous balloon compression for treating drug-resistant trigeminal neuralgia, were analyzed., Results: Post-operatively, transient palsy of the sixth nerve developed in 2 patients. According to their intraoperative radiographs, the side effect resulted from irregular balloon shape and inflation of the balloon towards the sellar floor., Conclusion: The anatomic position and the shape of the inflated balloon represent key factors in determining the procedure's benefit or risk of complications., ((c) 2009 S. Karger AG, Basel.)

During surgical exposure of the trigeminal root for the treatment of trigeminal neuralgia, biopsy specimens of the nerve root were taken in 12 consecutive patients. The biopsies were taken from areas as close as possible to the site of vascular compression, when present. The tissue was prepared for electron-microscopic evaluation. Except for 1 case, massive disruption of tissue ultrastructure was observed. The major findings included zones of de- and dysmyelination, juxtaposition of denuded axons, apparent axon loss and degeneration, and collagen deposition. Adjacent areas of normal root structure were present in most specimens. The ultrastructural changes observed in the biopsy samples demonstrate important pathology within the trigeminal root. Dysmyelination and the proximity of denuded axons in close apposition to each other support neurophysiological theories of pain production including ectopic electrogenesis, ephaptic contacts, and crossed after-discharge. The findings in this study demonstrate a pathophysiological basis for the syndrome of trigeminal neuralgia.

We analyzed 417 patients with trigeminal neuralgia who underwent microvascular decompression (MVD; n = 146) or percutaneous procedures, i.e. radiofrequency rhizotomy (RFR; n = 235) and glycerol rhizotomy (GR; n = 36) between March 1973 and December 1996. MVD and RFR showed the highest rates of initial pain relief (MVD 96.5%; RFR 92.3%; GR 82.8%). RFR and GR had 5.1 and 3.3% rates of facial dysesthesia, respectively, and MVD had the lowest rate (0.3%). Among 9 cases (8.6%) with recurrences after MVD, 8 cases underwent RFR and all of them obtained good long-term results (7.2 years on average). We concluded that MVD is the treatment of choice for tolerant younger patients and should be recommended for patients who desire no sensory deficit. We also determined that radiofrequency rhizotomy is the procedure of choice for patients in whom MVD failed.

From January 1, 1986, to June 30, 1996, 240 patients were operated on for trigeminal neuralgia: 182 patients were treated by thermocoagulation of the gasserian ganglion after Sweet and 58 patients by decompression of the trigeminal nerve after Janetta. In the thermocoagulation group, followed up for 6 months to 10 years 95.2% of the cases showed freedom from pain, in the Janetta operation group, followed up for 6 months to 6 years 98.5% showed freedom from pain. Thermocoagulation is the preferred therapy, especially in older patients in whom general anesthesia is risky, while the Janetta operation is the therapy of choice in younger patients.

The aim of the present study was to evaluate the long-term results of a series of 200 patients operated on by percutaneous compression of the gasserian ganglion (PCGG) according to Mullan and Lichtor's technique. The balloon was inflated for 6 min with 0.7 cm3 of iopamiro. We report excellent and satisfactory results in 62.5% of the cases and recurrence in 32.5% with a mean follow-up of 51 months. Severe sensory complications were rare (3%), whereas hearing disturbances were more frequent (11%). One unfortunate postoperative death was reported. With acceptable morbidity and in spite of this death, PCGG is an effective method which can easily be repeated in the treatment of trigeminal neuralgia.

We assessed thresholds for sensation of temperature and pressure and temporal summation of pain in the trigger area on the painful side and the contralateral nonpainful side in patients with trigeminal neuralgia previously treated with percutaneous retrogasserian glycerol rhizotomy (PRGR). Temperature and tactile thresholds were significantly increased on the painful side in both pain-free patients and patients with paroxysmal pain, but sensory loss was not more severe in patients with paroxysmal pain, except for increased warm thresholds. Abnormal temporal summation of pain (including progressive increase of pain intensity with radiation of pain and aftersensation) was present in the trigger area of patients with paroxysmal pain, but not in pain-free patients. Thus, relief of trigeminal neuralgia after PRGR involves normalization of abnormal temporal summation of pain, whereas sensory loss is less affected.

The results of Gamma Knife stereotactic radiosurgery in the management of 51 patients who had typical trigeminal neuralgia were evaluated at the University of Pittsburgh. In all cases, a 4-mm isocenter was targeted at the proximal nerve at the root entry zone. The target dose varied from 60 to 90 Gy. Forty-four patients (86%) had undergone prior surgery. The mean follow-up after radiosurgery was 9.6 months (range, 2-29 months). The initial response rate was 86%. At the last follow-up, 19 patients (37%) had excellent control (pain free), 21 (41%) had good control (50-90% relief), and 11 (21%) had failed treatment. No patient developed further sensory loss or deafferentation pain. A maximum radiosurgery dose > or = 70 Gy was associated with a significantly greater chance for complete pain relief. Using magnetic resonance imaging stereotactic targeting, the proximal trigeminal nerve is an appropriate anatomic target for radiosurgery. Gamma Knife radiosurgery is a useful additional surgical approach in the management of medically or surgically refractory trigeminal neuralgia.

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.

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.

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 influence of neuroeffector mechanisms in the regulation of postischemic cerebral blood flow was investigated by microsphere determination in 8 cats after chronic unilateral vascular deafferentation by trigeminal ganglionectomy. The animals were subjected to 90 min of reperfusion following 10 min of global ischemia induced by 4-vessel occlusion and systemic hypotension. Cortical hyperemia 30 min after reperfusion was attenuated by up to 48% in cortical gray matter ipsilateral to the side of trigeminal ganglionectomy (p less than 0.01). Axon reflex mechanisms involving the release of neuropeptides from peripheral sensory nerve fibers, such as substance P (SP), calcitonin gene-related peptide (CGRP) and neurokinin A (NKA), mediate this response. SP and NKA cause vasodilation by endothelium-dependent mechanisms (endothelium-dependent relaxing factor), whereas CGRP relaxes vascular smooth muscle by direct receptor interactions. Studies were therefore undertaken to determine the extent to which endothelium-dependent mechanisms mediate the hyperemia following global cerebral ischemia. In 7 intact cats, the postischemic response of pial arterioles to the topical application of acetylcholine (ACh; 10(-7) M), an endothelial-dependent vasodilator, was measured using a closed cranial window technique. Although ACh increased pial arteriolar caliber by 17% under resting conditions, the same dose elicited a vasoconstrictor response (87% of pre-ACh diameter 30 min after reperfusion) for the first 60 min of reperfusion after 10 min of ischemia. ACh-induced vasodilation was restored by 75 min (105%), but was less than control even at 120 min (109 vs. 117%; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

During percutaneous microcompression of the gasserian ganglion for the relief of trigeminal neuralgia, a computerized technique for monitoring the pressure inside Meckel's cave was employed in 22 patients. A dedicated transducer connected to a computer records the balloon inflation pressure. Its variations are discernible within tenths of a bar and are plotted in relation to time. The intraoperative pressure inside Meckel's cave is from 0.9 to 2.4 bars. When pressure was low, there was recurrence of pain. The highest values of pressure (1.9-2.4 bars) were observed in most of the patients suffering from untoward side effects. The clinical results seem to be influenced by the level of the intraoperative intracavitary pressure.

This study includes 127 patients treated for typical trigeminal neuralgia, 74 of whom underwent a percutaneous microcompression (PMC), 33 a radiofrequency thermocoagulation (RFT) and 20 were explored for microvascular decompression (MVD). A mean follow-up of 24 months was reached by all the groups. Pain relief was evaluated as an 'all or none' effect. At hospital discharge, pain had disappeared in 93.2% of the patients treated with PMC, in 81.8% of those treated with RFT, and in 85% of the MVD group. At 24 months the effect was maintained by 57.2% of the PMC group, 57.6% of the RFT, and by 75% of the MVD group. Marked dysesthesia was reported by 6.7% of the patients treated with PMC, and by 24.2% of those who received a RFT. Impairment of masticatory function was observed in 10% of the PMC patients. Ipsilateral hypoacusia and transient IV nerve palsy in 1 patient was the only major complication after MVD.

Between 1974 and 1984, 428 trigeminal neuralgia cases were treated by controlled radiofrequency thermocoagulation (RFTC). 29 had recurrent trigeminal neuralgia after intracranial surgery. 26 of the 29 patients were treated by retrogasserian rhizotomy and 3 by posterior fossa exploration. Among the 26 recurrent trigeminal neuralgia following retrogasserian rhizotomy, RFTC was effective in 23 cases (88.5%), and in 3 cases (11.5%) RFTC was effective for a short period. Repeated RFTC was unable to control the pain attacks which were later relieved by posterior fossa exploration and root section. Of the 3 recurrent trigeminal neuralgia following posterior fossa exploration, RFTC was effective in 2 cases (66.6%).

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.

37 procedures were carried out in 32 patients with trigeminal neuralgia who were unrelieved by anticonvulsants. Initial relief was achieved in 31 patients (98%). 5 patients (16%) suffered a relapse during a follow-up period of 15-26 months. Corneal anaesthesia occurred in 6 patients, 1 of whom subsequently developed a corneal ulcer. Anaesthesia dolorosa appeared in 5 patients. Ipsilateral reduction in hearing was reported by 2 patients. Despite its limits and complications percutaneous radio frequency gangliolysis is an effective alternative in the treatment of trigeminal neuralgia.

Indications, technical procedures, and complications are discussed for the performance of thermal electrocoagulation of the trigeminal preganglionic rootlets and gasserian ganglion. Specific steps in preoperative evaluation, premedication, anesthetic management, and technical performance of graded lesion-making utilizing radiographic control, physiologic stimulation and intraoperative patient monitoring are discussed. A survey of complications is presented.