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Although surgical ablative procedures can be effective in the management of chronic pain of malignant and non-malignant origin, they are often disregarded as treatment options due to the fact that in the past these procedures were associated with high complication rates. The complications include the development of new neurological deficits and in cases of long-term follow-up, the occurrence of the old or new pain syndromes by deafferentation. On the other hand there exist many less invasive, e.g. neuromodulatory procedures or non-invasive measures (systemic oral or transdermal opioids) which are able to considerably reduce chronic pain. Nevertheless, there remain certain very restricted indications for the use of neuroablative procedures for the treatment of chronic pain even today.

Therapy: Nowadays the theory of microvascular compression of the root entry zone of trigeminal nerve in case of trigeminal neuralgia is widely accepted. Pathological contacts between a-beta fibers and c-fibers are believed to be caused by an arterial compression in the root entry zone. It is these ephaptic contacts that have led to a logical therapeutic sequence of treatment by means of membrane stabilising agents like anticonvulsant drugs as carbamazepine, nonablative - and, in view of the pathophysiological concept, causal - surgery in form of microvascular decompression described by Jannetta and ablative operative methods, which are restricted to certain well-defined indications., Additional Procedures: Other and additional surgical procedures are of use only in cases of atypical facial pain or with therapy non-responders. Methods like Caudalis-DREZ-Lesion and specific techniques such as cervical superior ganglion infiltration with opioids are worth being mentioned.

The neuralgia of the trigeminal nerve is the most frequent neuralgia of the cranial nerves. It is mostly seen in the elderly. In younger patients it must always be suspected as a symptomatic neuralgia. The course is recurrent and progressive. Spontaneous temporary remissions are usual. Later the pain becomes more frequent, unbearable and disabling. At first the therapy is a conservative one, the drug of choice is Carbamazepin, alternatively Phenytoin and Baclofen. If the conservative therapy fails, the only possible treatment is a neurosurgical one. Nowadays all methods aim at the Gasserian ganglion. In use are several percutaneous transoval procedures or the microvascular decompression through a craniotomy. Our surgical procedure of choice is the percutaneous thermorhizotomy in the Gasserian ganglion and the nerve root, where the pain-conducting fibers are destroyed, preserving tactile sensibility. This procedure is practically without vital hazards for the patient. It is applied in local anesthesia and a short intravenous analgesia. The recurrence rate of 32% is considerable, but the procedure can be repeated. The success cannot be deduced from the recurrence rate alone but must take into account the side effects of the procedure. These are mainly a loss of sensibility to touch by too aggressive rhizotomy and anesthesia of the cornea. By the criteria explained in the text we achieved a good result in 44%, a fair one in 25%, an indifferent one in 10% and a poor result in 7%. In 14% the result is unknown.

Trigeminal neuralgia is an exactly defined syndrome with a non-uniform aetiology but an obviously uniform pathogenesis. A subdivision in an idiopathic and a symptomatic type is non-essential. In a part of the cases microvascular compression of the sensory root may be the cause of trigeminal neuralgia but there are some good arguments against this concept. Other causes such as multiple sclerosis, acoustic neuroma or carotid aneurysm are well known. The principle of neurosurgical procedures is either an interruption of the pain-conducting fibres or a non-specific manipulation at the Gasserian ganglion or the sensory root with the result of an interruption of abnormal ephapses and short-circuits which may recur later on. So microvascular decompression should not be considered to be a specific and causal therapeutic approach as well as the therapy of first choice for all cases.

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.

The trigeminal neuralgia has to be differentiated from the trigeminal neuropathy in respect of pain character and etiology. The neuralgia is characterized by paroxysmal pain evoked by trigger stimuli. The most frequent cause of this type of pain is a parapontine vascular compression of the trigeminal root without neurological deficits. The symptoms of neuropathy are some sensory loss associated with continuous pain resulting from peripheral damage of the trigeminal nerve. This distinction alleviates the indication for specific operative procedures and is more precise than the subdivision in typical and atypical neuralgia. The results of neurovascular decompression and thermorhizotomy can be much improved if neuropathic pain syndromes are excluded from operation. Out of 180 patients suffering from trigeminal neuralgia 94% were pain-free after neurovascular decompression and 96% of 144 patients following thermorhizotomy. For the treatment of continuous neuropathic pain augmentative electrostimulation of the Gasserian Ganglion via implanted electrodes is recommended.

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.

owing to an enormous development in the operative technical possibilities, percutaneous surgical methods are available today for both destructive and functional pain interventions, so that the surgical risk can be reduced to a minimum and also patients in a poor general condition and of advanced age can tolerate these interventions at any time.

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.

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.

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.

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.

Sweet's method for thermocoagulation of the Gasserian ganglion is a real advance in the operative treatment of trigeminal neuralgia. The advantages of this method are obvious: minimum operation risk, minimum complication rate, short postoperative convalescence, shorter confinement to hospital and finally the possibility of repeating the operation without risk in the event of a relapse.