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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.

Background: Conventional percutaneous thermocoagulation of postgasserian fibers has shown high success rates, with significant residual morbidity., Methods: This communication summarizes conclusions of multiple publications on our computerized mapping method and technique, and presents new data on short- and long-term results on trigeminal pain, including an actuarial analysis, complications., Results: In TTN, 97.4% of 75 procedures produced initial pain relief without medication. In all, 84.7% of appropriate verbal responses were achieved by proper location of the needle at the chosen target, requiring an average of 1.45 tracts per procedure. Needle tip was located between 1 and 15 mm below the sellar floor in 97.0% of procedures and in an angle of 40 degrees to 80 degrees regarding the clivus profile projection in 99.1%. A 93% reduction of corneal analgesia and a 100% suppression of major dysesthesias and cranial nerve palsies were found., Conclusion: We have shown a significant reduction of morbidity from percutaneous thermocoagulation of postgasserian fibers with similar short- and long-term results as those shown in 11 recently selected series. Strict adherence to all details of our new method and technique is essential. Future multiinstitutional studies are needed to confirm and enrich this small series.

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.

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.

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.

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.

A series of 16 patients with meningiomas of Meckel's cave is reported. Trigeminal neuralgia, typical or atypical, was the initial symptom in 10 patients (62.5%). At admission, trigeminal signs and symptoms were present in 15 patients (93.7%); in 7 patients (43.7%), trigeminal dysfunction was combined with the impairment of other cranial nerves. On retrospective analysis, these patients fall into two clinical groups that differ also in prognosis. Group 1 comprises eight patients with trigeminal signs and symptoms only. These patients had small meningiomas strictly affecting Meckel's cave. Total removal of the tumor was achieved in seven of eight patients, without adjunctive postoperative neurological deficits. In this group, there were no tumor recurrences. Group 2 comprises the other eight patients in whom trigeminal dysfunction was combined with impairment of other cranial nerves. These patients had large tumors arising from Meckel's cave and secondarily invading the cavernous sinus (five patients) or extending into the posterior fossa (two patients) or largely growing into the middle fossa (one patient). Total removal was achieved in only one patient, and a worsening of the preoperative neurological status was observed in four patients; there were three cases of tumor progression. A subtemporal intradural approach (used in the past in every case) is still used for the small tumors of Group 1 with good results. Since 1985, for tumors involving the cavernous sinus, we have employed a frontotemporal craniotomy with extradural clinoidectomy and superior and lateral approach to the cavernous sinus. When the tumor extends toward the posterior fossa, we use a combined temporosuboccipital-transpetrosal approach.(ABSTRACT TRUNCATED AT 250 WORDS)

The authors reviewed a series of 38 consecutive patients with trigeminal neuralgia treated by percutaneous thermocoagulation in 1984-90. In 10 patients in whom the result of the treatment was unsatisfactory the coagulation was repeated (in 2 out of 10 twice). The analysis of the results showed that good outcome was connected with permanent anaesthesia in the area innervated by the coagulated branch. If anaesthesia was not present 24 hours after the treatment, it suggested that an insufficient lesion was done and consequently unsatisfactory result was likely. In patients in whom there was a sensory impairment after either thermocoagulation or other form of treatment (injection of alcohol or rhizotomy) repeated thermocoagulation not only did not give good results but could lead to worsening of the pain.

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.

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%).

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.