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Objective: Percutaneous treatments for trigeminal neuralgia are safe, simple, and effective for achieving good pain control. Procedural risks could be minimized by using noninvasive imaging techniques to improve the placement of the radiofrequency thermocoagulation probe into the trigeminal ganglion. Positioning of a probe is crucial to maximize pain relief and to minimize unwanted side effects, such as denervation in unaffected areas. This investigation examined the use of laser speckle imaging during probe placement in an animal model., Methods: This preclinical safety study used nonhuman primates, Macaca nemestrina (pigtail monkeys), to examine whether real-time imaging of blood flow in the face during the positioning of a coagulation probe could monitor the location and guide the positioning of the probe within the trigeminal ganglion., Results: Data from 6 experiments in 3 pigtail monkeys support the hypothesis that laser imaging is safe and improves the accuracy of probe placement., Conclusions: Noninvasive laser speckle imaging can be performed safely in nonhuman primates. Because improved probe placement may reduce morbidity associated with percutaneous rhizotomies, efficacy trials of laser speckle imaging should be conducted in humans.

Idiopathic trigeminal sensory neuropathy is a clinically benign disorder in which the main feature is facial numbness limited to the territory of one or more divisions of the trigeminal nerve; the disorder persists for a few weeks to several years. and no underlying disease can be identified. Magnetic resonance (MR) imaging findings are occasionally consistent with a small trigeminal neuroma of the left gasserian ganglion associated with idiopathic trigeminal sensory neuropathy. The authors report on two patients who were treated using a skull base approach in which the gasserian ganglion was exposed and the lesion was removed. The pathological diagnosis was chronic granulomatous neuritis. The authors conclude that, in patients with MR findings suggestive of a small trigeminal neuroma, benign idiopathic trigeminal sensory neuropathy should also be considered in the differential diagnosis. A conservative approach featuring sequential MR imaging studies may avoid an unnecessary surgical exploration.

Percutaneous procedures for treating trigeminal neuralgia involve the penetration of foramen ovale using cutaneous landmarks and radiological guidance. The placement of radiopaque markers over the commonly used "zygomatic points" in front of the ears provides landmarks on intraoperative radiological studies that facilitate localization of the foramen ovale. Speed and safety of percutaneous trigeminal procedures should be enhanced. There is no increase in radiation exposure over that in other commonly used approaches.

A retrospective review of 12 cases of meningioma of Meckel's cave involving the Gasserian ganglion or the trigeminal posterior root (or both) seen at the Mayo Clinic during a 20-year period suggested three clearly defined clinical groups. One group (the largest) had typical trigeminal neuralgia and an excellent prognosis after the removal of the easily detachable mass that was impinging on the ganglion. A second group, with meningiomas en plaque embedded in the ganglion, had a history of atypical trigeminal face pain without neurological deficit, but the prognosis for pain relief was not as good as in the previous group. A third group had a history of face dysesthesias and pain, objective trigeminal sensory loss, and multiple cranial nerve deficit; these patients had meningiomas with histological signs of mitotic activity and a poor prognosis, with return of intractable pain and recurrence of the tumor.

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.

The authors described a fluoroscopic method of guiding percutaneous needle penetration of the foramen ovale. The advantages are simplicity, speed, accuracy, and comfortable patient positioning. Radiation exposure is minimized.