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Background: Percutaneous trigeminal rhizotomy (PTR) uses fluoroscopic guidance to cannulate the foramen ovale for the treatment of trigeminal neuralgia., Objective: To describe the use of a high-resolution biplane neuroangiosuite for PTR and retrospectively to assess the performance of this technique., Methods: From 1990 through 2010, 67 PTRs were performed in 51 patients at our institution; 47 used the c-arm in the operating room (OR) and 20 used the biplane angiosuite. Hospital charts were reviewed for demographics, symptomatology, operative time, number of cannulation attempts, fluoroscopy time and pain outcome. Two-tailed univariate analyses were performed to compare the OR and angiosuite groups., Results: In 20 of 67 PTRs, biplane fluoroscopic guidance in the angiosuite was used. Variations in type of PTR, fluoroscopy technique and follow-up time barred meaningful comparison of these variables between OR and biplane groups. However, the biplane group had significantly fewer mean cannulation attempts (1 vs 2.2, p<0.001)., Conclusions: High-resolution biplane neuroangiosuites offer a readily available alternative to ORs for PTR in the treatment of trigeminal neuralgia. Use of the biplane fluoroscopy machine was practical, safe and at least as effective as the use of the c-arm. It may also offer the advantages of a reduced number of cannulation attempts., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)

Objective: To report a case of patulous eustachian tube which occurred after percutaneous balloon microcompression of the Gasserian ganglion., Method: Retrospective case review., Results: A 41-year-old man was referred to our audiovestibular medicine department following episodes of autophony. These symptoms appeared two weeks after percutaneous balloon microcompression performed to treat severe trigeminal neuralgia secondary to multiple sclerosis. A diagnosis of patulous eustachian tube was indicated by clinical examination and tympanometry. The symptoms were present for less than six months and improved without any specific treatment., Conclusion: Percutaneous balloon microcompression is a procedure used for refractory trigeminal neuralgia that can cause transient sensory and motor deficits of any of the trigeminal nerve branches. It is proposed that injury to the mandibular division in this case caused temporary tensor veli palatini dysfunction with consequent patulous eustachian tube.

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.

Objectives/hypothesis: We describe our cadaveric dissections and clinical findings that address anterior and ventral limitations imposed by the trigeminal nerve. Particularly, we identify the trigeminal caroticodural fold, the vestment of dura that traverses the space between the nerve and the internal carotid artery. We address the effect of mobilization of this fold to optimize access in Kawase's space when approaching the clivus and posterior fossa., Methods: Histological study and cadaveric dissections were performed to examine this regional anatomy. Our clinical series (2002 to 2007) includes 30 patients who underwent anterior petrosectomy as part of more complex approaches for lesions of the skull base., Results: Histological and dissection specimens showed a dense fibrous confluence lateral to the trigeminal ganglion and portions of the trigeminal nerve that we called the trigeminal caroticodural fold. This fold was prominent in 18 patients, ill-defined in six, and absent in six patients. Incision of the trigeminal caroticodural fold permitted between 1 mm and 3 mm of additional exposure for drilling in Kawase's space without direct trauma to V(3)., Conclusions: Our study highlights the existence of a dural tethering of the trigeminal nerve and ganglion relevant to surgical exposure of Kawase's space. The regional dural anatomy that contributes to the trigeminal caroticodural fold is complex with subtle variances. We suggest that identification of this fold and its sharp dissection allows mobilization of the trigeminal ganglion and nerve without violation of V(3), and ultimately can improve the transpetrosal access to the upper clivus and posterior fossa via this corridor. Laryngoscope, 2009.

The percutaneous Hartel transoval route goes through an inverted pyramid, with an inferior summit and a superior base that includes three compartments. The danger of the inferior compartment is the parotid duct. The middle compartment contains many branches of the mandibular nerve. The superior compartment is crossed by the internal maxillary artery and its branches, as well as the auditory tube. The base of the pyramid presents not only the foramen ovale, but also the foramen lacerum, where the trocar may injure the internal carotid, and the foramen jugulare, where the trocar may meet the internal jugular vein and nerves of the pars nervosa (IX, X, XI). The trigeminal cave contains, within the trigeminal cistern, the trigeminal ganglion, extended backward by the triangular plexus (the target for thermocoagulation). These structures are undercrossed by the masticatory motor branch of the trigeminal nerve.

We aim to evaluate the mechanisms responsible for complications during trigeminal rhizotomy via foramen ovale puncture. Ten dry skulls and 10 skull-base specimens were investigated in the present study. In cadaveric skull-base specimens, the anatomical relationships between the foramen ovale, mandibular nerve and Gasserian ganglion and the surrounding neurovascular structures were investigated intradurally. The distance between the foramen ovale and Gasserian ganglion was measured as 6 mm. The abducent nerve, adjacent to the anterior tail of the petrolingual ligament, was observed passing along the lateral wall of the cavernous sinus. Advancement of the catheter more than 10 mm from the foramen ovale is likely to damage the internal carotid artery and the abducent nerve at the medial side of the petrolingual ligament. Thermocoagulation of the lateral wall of the cavernous sinus may damage the cranial nerves by heat, giving rise to pareses.

Neurotrophic keratopathy (NK), a consequence of sensory denervation of the cornea, must be better understood in order to develop new approaches to therapy. The purpose of this study was to create a rat model for neurotrophic keratopathy by denervating the trigeminal nerve through a ventral approach with stereotaxic surgery. Stereotaxic coordinates were measured in 46 male Sprague Dawley rat cadavers for localization of V1. After further refining the coordinates in nine live animals, radiofrequency ablation was chosen as an effective method of disrupting the innervation to the cornea. Fifty-two live rats were treated with radiofrequency ablation to define the anatomical localization of the lesion by utilizing gross and histopathological studies. A gross lesion of the trigeminal nerve and/or ganglion was observed in 47 (90%) of the 52 animals. Histopathological studies revealed that all 52 animals had anatomical damage of the trigeminal innervation to the eye. Low mortality and little morbidity were observed in these animals. We have developed a rat model for neurotrophic keratopathy that is simple to produce, accurate in creating a lesion by utilizing stereotaxic techniques combined with radiofrequency ablation, and successful in decreasing morbidity and mortality.

The techniques of two experimental surgical operations on the trigeminal nerve are described, namely, excision of the trigeminal ganglion (ganglionectomy) and division of the trigeminal root (rhizotomy), in the cat. These techniques have been developed with the specific aims of achieving the trigeminal lesion and also preserving a satisfactory postoperative quality of life for the animal in order to make it possible to study the long-term effects of trigeminal dennervation. To the best of our knowledge, a detailed description of such a surgical methodology is lacking; reporting of these procedures may facilitate future research on the trigeminal nerve.

Twenty-three patients with intractable trigeminal neuralgia were treated by a modified technique of middle fossa extradural decompression of the trigeminal sensory root at the petrous ridge. After exposing the ganglion and the root at the petrous ridge, by an extradural Frazier's approach a thin layer of autogenous fat was interposed between the dura propria and the middle fossa dura anteriorly, and between the petrous ridge and the root posteriorly. The fat layers were used to prevent dural adhesions and to maintain a space between the petrous ridge and the root. The dura propria was preserved intact. All patients obtained immediate relief of pain following surgery. Twenty patients continue to remain pain free. Two patients have mild occasional pains and one has a persistent pain of moderate intensity. One patient developed a dense sensory loss and two had delayed facial weakness which recovered completely within a month. The mechanism of trigeminal neuralgia is discussed on the basis of anatomical, histopathological and electrophysiological findings and the rationale of middle fossa decompression of the root is stressed. This method is short, simple and safe and may serve as an alternative to the more recent methods of treating trigeminal neuralgia.

We report a large trigeminal neurinoma in an 18-month-old child involving the Gasserian ganglion and all three divisions in a plexiform pattern. The tumour in the ophthalmic division extended all the way to the supraorbital nerve. The child presented with proptosis which had been observed since she was 4 months of age. There was a family history of neurofibromatosis.

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.

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.

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.

We report on diagnosis, treatment and clinical course of a solitary schwannoma of the trigeminal nerve with consecutive metastatic spread in a 45-year-old woman. The patient presented a temporal lobe syndrome with psychomotor seizures. Trigeminal nerve function was intact apart from a transient hypaesthesia in the mandibular branch. Assuming a meningioma the tumor was removed via a temporal approach. Secondary to the definitive histological diagnosis radiation therapy was performed. After that the patient was symptom-free. 4 months later a large recurrent tumor was found involving the cavernous sinus and the pterygopalatine fossa. In a second operation the tumor was resected intra- and extradurally through an infratemporal preauricular approach in cooperation with an oral and maxillo-facial surgeon. At this time multiple pulmonary metastases developed showing no response to polychemotherapy (EVI). The patient died 13 months after onset of the disease. Hitherto, only 5 cases of a primary malignant schwannoma of the trigeminal nerve have been published in the world literature.

A 39-year-old woman had a large benign intracranial schwannoma of the Gasserian ganglion. Thirty-two years previously, she had an embryonal rhabdomyosarcoma of the orbit. She had been treated by enucleation, local excision, and low-dose supplemental irradiation (1,400 rads). This is the longest survival of which we are aware following any treatment modality in such tumors. No correlation between the two tumors has been established.

The results of EEG investigations after Spiller-Frazier's operation for trigeminal neuralgia in 112 patients are reported. Follow-up EEGs were recorded within 1-8 years after surgery; two to three follow-up tracings were available in 53 patients. Two distinct phases of EEG alterations were noted: 1) The immediate postoperative phase characterized by bilateral delta waves of maximal distribution in the frontal-precentral area and in the temporal area on the side of surgery. Such alterations are supposedly due to postoperative edema or associated metabolic disturbances. 2) Several months after surgery focal abnormalities of the temporal lobe develop, which consist of high amplitude alpha-, beta- or theta-waves, sharp waves, spikes and occasional stypical spike-and-wave complexes. These abnormalities are reflected on the contralateral side in approximately one third of the case. Repeated EEGs confirmed the consistency of degree and location of these findings with the exception of a less constant incidence of spikes and sharp waves. Severity of EEG abnormalities and incidence of potentially epileptogenic discharges increases with age. In spite of the precarious location of such focal abnormalities in the temporal lobe only 3 of 112 patients (2.7%) reported seizures with temporal lobe features. The age of the three patients was below the average age of 59.1 years. Seizures occurred sporadically beginning approximately 2 years after surgery. The low incidence of seizures may in our opinion be due to the advanced age of most patients.

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%.

A patient is described with aspergillus flavus granuloma of the trigeminal ganglion. The patient was effectively treated by surgical excision of most of the infected tissue followed by intensive chemotherapy with amphotericin B and flucytosine.

Lesions of the peripheral part of the trigeminal nerve may cause trigeminal neuropathy associated with severe pain. Such pain usually does not respond to carbamazepine and analgesics, and it is continuous and lacks the characteristic paroxysmal character of tic douloureux. These patients often present with complex changes of facial sensibility in the form of dysesthesia, hyperalgesia, and allodynia. The pain sometimes responds favorably to transcutaneous nerve stimulation, but direct stimulation of the trigeminal ganglion and rootlets via an implanted electrode provides a greater likelihood of pain relief. Fourteen patients diagnosed as having painful trigeminal neuropathy received implants of a gasserian ganglion-stimulating electrode. The mean follow-up period is 4 years (range, 1 to 7 years). Eleven of the patients have retained the pain-relieving effect, and 1 had pain disappear without further stimulation. Eight of the patients estimated their pain relief to be complete or very good. There were no serious complications, but in several of the patients the electrode had to be exchanged because the insulation of the lead wires broke. For the selection of patients for permanent electrode implantation, a method has been developed for trial stimulation via a percutaneous electrode introduced into the trigeminal cistern. Temporary trial stimulation can be performed for several days. It is concluded that stimulation of the trigeminal ganglion and rootlets with the aid of an implanted electrode may effectively relieve certain forms of trigeminal pain that are otherwise extremely difficult to manage.

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%).

These first ultrastructural studies of the effect caused by thermocoagulation of a ganglion (ganglion inferius nervi vagi) akin to the Gasserian ganglion have shown that selective pain fiber elimination can only be expected from thermocoagulation at temperatures not higher than 50 degrees C/60 s or 60 degrees C/60 s. Even if the results of these animal experiments can only be applicable to clinical practice in the sense of an analogical conclusion, we are nevertheless of the opinion that it can be recommended to begin the thermocoagulation in trigeminus neuralgia at low temperatures (50 degrees C/60 s or 60 degrees C/60 s) and only if found necessary, after checking the sensitivity to pain, to increase it in steps of 5--10 degrees C.

This study determined the cardiovascular effects of percutaneous radiofrequency coagulation of the Gasserian ganglion, performed under neuroleptanalgesia and intermittent ultrashort-acting barbiturate anaesthesia. Twelve ASA physical status class II patients were studied. Highly significant increases in mean heart rate and arterial blood pressure followed the insertion of the cannula electrode into the Gasserian ganglion (p less than 0.001). In six randomly assigned patients severe tachycardia and hypertension also accompanied the progress of the thermal lesion (p less than 0.0001). Three patients developed premature ventricular contractions, and two developed significant ST segment depression. Intravenous nitroglycerin, used during current generation, successfully controlled the hypertensive response in the other six patients. In percutaneous thermocoagulation of the Gasserian ganglion the patient's co-operation is essential. In addition to providing suitable operating conditions for both surgeons and patient, we should also be able to maintain normal and stable cardiovascular haemodynamics. Intravenous nitroglycerin used as an adjunct to light general anaesthesia safely maintained intraoperative normotension. It is also suggested that patients with coronary artery disease be adequately monitored and protected during the procedure.

A case of carotid-cavernous fistula following percutaneous trigeminal ganglion approach is presented. The case was treated by a combination of trapping and embolisation of the carotid artery. Percutaneous approach to the trigeminal ganglion via the foramen ovale was described by Taptas (1911) and Hartel (1914). Since then this procedure has been used in large series, for the injection of alcohol (Harris, 1940), electrocoagulation (Kirschner, 1942) or the injection hot water (Jeager, 1957) to the trigeminal ganglion for the treatment of trigeminal neuralgia. In 1965 White and Sweet used the percutaneous trigeminal ganglion approach for the radio-frequency (R.F.) thermocoagulation of the trigeminal ganglion. This procedure is a simple and safe method. It has been used in large series in the treatment of trigeminal neuralgia. In our department we have performed 252 R.F. thermocoagulation of the gasserion ganglion in 228 patients since 1975. In 252 interventions using the percutaneous trigeminal ganglion approach, via the foramen ovale, we observed only one carotid-cavernous fistula following the procedure. This is the second report in the literature of a carotid-cavernous fistula following the percutaneous trigeminal ganglion approach.

Immunoreactive substance P is present in measurable amounts in pia arachnoid from rat, cat, dog and calf. Levels of substance P in this tissue are comparable to those found in peripheral structures receiving innervation from dorsal root or trigeminal ganglia. Separation and measurement of bovine pia-arachnoid extract by reverse phase high performance liquid chromatography and radioimmunoassay reveals a single peak of activity with a retention time identical to that of substance P. Unilateral lesions of the trigeminal ganglia decrease substance P levels within cat pia arachnoid and accompanying blood vessels ipsilaterally by greater than 50%. These data indicate that most of the substance P surrounding pial blood vessels resides within afferent nerve fibres from trigeminal ganglion cells.

The authors report their experience of the treatment of essential trigeminal neuralgia by percutaneous thermocoagulation of the Gasserian ganglion (400 patients). This method has always been performed on anesthetized patients, using an ultra short acting barbiturate: methohexital. Most often, two or three successive coagulations are needed to obtain the desired analgesia. No complications have resulted, although 30 p. cent of our patients were over 70 years old.

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)

We report about hypertensive crises, cardial arrhythmia and respiratory complications in 47 patients undergoing thermocoagulation of the gasserian ganglion. Therapeutic proposals are discussed.

Among the complications after surgical interventions carried out on the Ganglion semilunare because of a trigeminal neuralgia the reason why Keratopathia neuroparalytica plays a role is the fact that it very frequently leads to partial or total blindness of the affected eye. The pathogenesis of the keratopathy is still being disputed. The appraisal of the various surgical methods in trigeminal neuralgia always includes the frequent occurrence of a keratopathy. Among the 171 patients who were operated on in Halle because of trigeminal neuralgia in the last ten years no keratopathy was observed. In 12 cases a reduction or removal of the corneal reflex was brought about. On 8 patients a postganglionic intradural operation was carried out, all others received an electro-coagulation. The co-operation with the ophthalmologist is indispensable both prophylactically and therapeutically.

Thirty-eight patients with facial pain in the trigeminal distribution have been treated by percutaneous coagulation of the trigeminal ganglion. Although use has been made of radiological criteria, it has been found from the physiological data obtained from stimulation that motor and sensory phenomena provide more information of electrode placement and that good pain relief results when these criteria are met. The advantages of the method are: (i) minimal operative risk; (ii) control of the extent of the lesion created; (iii) small sensibility deficit; (iv) minimal complication rate; (v) short hospitalization; (vi) satisfactory result in more than 90% of patients; (vii) no recurrence of pain to date.

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.

The development of a facial flush during thermocoagulation of the Gasserian ganglion was monitored in 16 patients with pulse recording techniques and in a further 17 patients with thermography. There was a close association between the development of the facial flush in the distribution of one or more divisions of the trigeminal nerve and the subsequent demonstration of postoperative analgesia. In regions where significant changes took place, vascular pulsations increased 25-233% (mean 96%) and facial temperature rose 0.5-2.0 degrees C. The response persisted for up to an hour postoperatively, and was not diminished in patients with pre-operative analgesia from a previous procedure. Possible mechanisms for the facial flush, including stimulation of an active vasodilator system, the antidromic release of vasoactive substances from trigeminal nerve terminals and the release of tonic vasoconstriction are discussed. A practical application of the pulse recording technique used in the present investigation would be to monitor the distribution of vasodilatation at operation to avoid unwanted first division sensory loss.

Voltage and current within Gasserian ganglion have been measured during a therapeutical high frequency coagulation of the Gasserian ganglion in 25 consecutive cases. From these values, the impedance (Ohm), the work (Watt) and the total energy (Joule) necessary to obtain an analgesia without anesthesia have been calculated. The study has shown that the temperature and the time of coagulation in correlation with the length of the non isolated tip of the electrode are actually the only constancy in the control of the therapeutical lesions.

Two cases of Gasserian ganglion neurinomas in children are described. The onset in both cases was insidious and the tumors became very large before the first clinical signs appeared. Blindness of one eye by direct compression of the homolateral optic nerve was the main symptom in both instances. In one child homolateral exophthalmus was also present. The clinical course of both cases was completely painless and without any other sign of involvement of the trigeminal nerve. Abnormal vessels related to the tumor were visible in the arterial phase of carotid angiography. This angiographic finding (unique in appearance and distribution) may be considered as pathognomonic for tumors of the Gasserian ganglion.

A rare tumor closely associated with the trigeminal ganglion produced a syndrome of atypical facial pain in a 44-year-old man. Two previous reports have designated similar tumors as "fibro-osseous lesions." The distinctive morphological appearance is illustrated and possible histogenesis discussed.

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.

In 250 patients with tic doulourex an percutaneous radiofrequency coagulation of the gasserian ganglion has been performed. In 92.2% of the cases the patients were post-operatively painfree. The follow-up extended in 122 cases over 7 years. In these patients a pain recurrency was noted in 27%. On behalf of low invasivity of the procedure the radio-frequency coagulation of the gasserian ganglion is a recommendable operation with low risk and high efficiency especially in old patients.

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.