Ronald Brisman

Trigeminal Nerve-Blood Vessel Relationship as Revealed by High-resolution Magnetic Resonance Imaging and Its Effect on Pain Relief after Gamma Knife Radiosurgery for Trigeminal Neuralgia.

OBJECTIVE Blood vessel (BV) compression of the trigeminal nerve (Cranial Nerve [CN] V) is a common cause of trigeminal neuralgia (TN). High-resolution magnetic resonance imaging scans obtained during gamma knife radiosurgery (GKRS) in patients with TN may be used to analyze the BV-CN V relationship. Follow-up data from a large series of patients treated with GKRS for TN were used to provide information regarding the BV-CN V relationship and pain relief. METHODS T1-weighted, axial 1-mm-thick volume acquisition magnetic resonance imaging scans were obtained through the area of CN V at its exit from the brainstem after injection of 15 ml of gadolinium. The BV-CN V relationship on the symptomatic side that was treated with GKRS was categorized into the following groups: Group 1 (no close relationship), Group 2 (BV close to CN V but not touching it), and Groups 3 and higher (BV-CN V contact). RESULTS A total of 181 symptomatic nerves were studied in 179 patients with TN who were treated with GKRS. In BV-CN V Groups 1, 2, and 3 and higher, respectively, were 43 sides (24%), 31 sides (17%), and 107 sides (59%). In 100 sides where there was no surgical procedure before GKRS, 50% or greater pain relief was more likely in those with BV-CN V contact (51 [88%] of 58 sides) than in those without BV-CN V (29 [69%] of 42 sides) (P = 0.024). BV-CN V contact was observed more often in men (55 [69%] of 80 sides) than in women (52 [52%] of 101 sides) (P = 0.023) and more often in patients who had unilateral TN (104 [62%] of 169 patients) rather than bilateral TN (2 [20%] of 10 patients) (P = 0.016). CONCLUSION In patients who have not undergone previous surgery for TN, BV-CN V contact revealed by high-resolution magnetic resonance imaging may indicate a particularly favorable response to GKRS.

Trigeminal nerve stimulation Short latency somatosensory evoked potentials

We have devised a technique to measure trigeminal somatosensory evoked potentials, stimulating the mentalis nerve at the mandibular foramen and recording the evoked early potential on the scalp at 3.2 msec. The early potential was easily recognized in all normal subjects and on the asymptomatic side of patients with facial pain. The latency of the early potential in normals was 1 to 2 msec less than half the latency of the mechanically induced jaw jerk. The early potential appeared simultaneously on both sides after stimulation of either the right or left mentalis nerve and may have its origin in deep brainstem structures, the Gasserian ganglion, or the trigeminal nerve. The technique is useful in documenting the functional integrity of peripheral and central afferent pathways of the trigeminal nerve.

Computed tomography of disseminated meningeal and ependymal malignant neoplasms

We studied computed tomography (CT) scans of 50 patients with clinical signs and symptoms compatible with disseminated meningeal tumor, all documented by cerebrospinal fluid cytology, surgical biopsy, or autopsy. Twenty-three patients also had nuclear scans, and 13 had cerebral angiograms. Represented in the series were patients with metastatic carcinoma, gliomas, and lymphomas. The characteristic CT findings included gyral enhancement without edema; sulcal and basilar cisternal obliteration and enhancement, and ependymal-subependymal enhancement. The correct diagnosis was made by CT in 28 of the 50 cases (56%).

Repeat Gamma Knife Radiosurgery for Trigeminal Neuralgia

Background: Although gamma knife radiosurgery (GKRS) has been shown to be safe and effective for the treatment of trigeminal neuralgia (TN), there are few studies that report the results of a second GKRS. Method: Between May 22, 1998 and April 1, 2003, we treated 335 primary TN patients with GKRS. All received a maximum dose of 75 Gy to the cisternal trigeminal nerve. 45 patients with recurrent or persistent TN were treated with a maximum dose of 40 Gy at a second GKRS and were available for at least 6 months of follow-up. Results: Final pain relief (mean of 15 months after second GKRS) was 50% or greater in 28 of the 45 patients (62.2%). Patients who had no neurosurgical procedure prior to their first GKRS were more likely to have pain relief of 50% or greater following the second GKRS (p = 0.042). Significant new dysesthesias (score greater than 5 on a scale of 0–10) developed in 2 patients (4.4%). Conclusion: Repeat GKRS has a good chance of relieving TN pain without complications and is more likely to relieve pain in those who did not have any procedure prior to their first GKRS.

Constant Face Pain in Typical Trigeminal Neuralgia and Response to Gamma Knife Radiosurgery

Background/Aims: Constant pain, especially if prominent, is sometimes considered incompatible with a diagnosis of typical idiopathic trigeminal neuralgia. This study aims to clarify the frequency of patient-reported constant pain in patients with medically intractable, typical, idiopathic trigeminal neuralgia as diagnosed with standard clinical parameters and confirmed by the response to a modified McGill questionnaire, a ‘hold-still’ test that eliminated triggers and the response to Gamma Knife radiosurgery. Method: Forty consecutive patients with typical trigeminal neuralgia were given questionnaires prior to Gamma Knife radiosurgery. Those with constant pain were further tested by being advised to hold completely still for up to 3 min. Final pain relief was evaluated after Gamma Knife radiosurgery. Results: Twenty of forty patients indicated on a questionnaire that they had constant face pain. Pain decreased on the ‘hold-still’ test on all 12 patients who were tested. Following Gamma Knife radiosurgery, there was no significant difference in pain relief in those without or with constant pain. Conclusion: Patients with typical idiopathic trigeminal neuralgia frequently report that 50% or more of their pain is constant. This constant pain is markedly decreased if the patient holds completely still for a few minutes and does not affect the outcome of Gamma Knife radiosurgery.

Computed Tomography of Cerebrospinal Fluid Dissemination of Malignant Neoplasms

The clinical diagnosis of all forms of disseminated meningeal malignancy, including metastatic carcinoma, lymphoma, and primary brain tumor, is difficult because of the multitude of nonlocalizing signs and symptoms.3,11,14 Computed tomography (CT), however, in conjunction with clinical history, frequently facilitates making this diagnosis. The purpose of this chapter is to review the characteristic CT observations demonstrated by our studies1,2 and corroborated by others.7,16

Image Registration Strategy of T 1 -Weighted and FIESTA MRI Sequences in Trigeminal Neuralgia Gamma Knife Radiosurgery

Background/Aims: In Gamma Knife radiosurgery, T1 MRI is most commonly used and is generally sufficient for targeting the trigeminal nerve. For patients whose trigeminal nerves are unclear on T1 MRI, FIESTA MRI supplements anatomical structure visualization and may improve trigeminal nerve delineation. The purpose of this study was to develop a registration strategy for T1 and FIESTA MRIs. Methods: We conducted a retrospective study on 54 trigeminal neuralgia patients. All patients were scanned with T1 and FIESTA MRIs. We evaluated 4 methods of registration: automatic image definition, superior-slice definition, middle-slice definition and inferior-slice definition. Target discrepancies were measured by deviations from an intracranial landmark on T1 and FIESTA MR images. Results: The overall range in registration error was 0.10–5.19 mm using superior-, 0.10–1.56 mm using middle- and 0.14–2.89 mm using inferior-slice definition. Registration error >2 mm was observed in 11% of the patients using superior-, 4% using middle- and 7% using inferior-slice FIESTA MRI definition. Conclusions: Among patients for whom FIESTA and T1 MRI are used, registration based on middle-slice definition reduces registration error and improves targeting of the trigeminal nerve.

BCNU and Steroids in the Viral-Induced Dog Brain Tumor

Schmidt-Ruppin strain of Rous Sarcoma was inoculated intracerebrally into 27 newborn beagle dogs. Fourteen days after viral inoculation, 13 of the dogs were given intravenous BCNU (1 mg/kg). The other 14 were given the same volume of intravenous saline in a randomized, double-blinded fashion. Ninety percent of all dogs developed intracranial tumors. Radionuclide (mercury 197) brain scans were done on each dog at 2-week intervals. Median survival was 113 days in the BCNU group and 115 days in the placebo group (P > .99). Unequivocally positive radionuclide brain scans were detected in 5 dogs treated with BCNU and in 2 of the controls. There were no gross or microscopic differences at autopsy between treated and nontreated animals. BCNU, as given in this animal brain tumor model, did not demonstrate any oncolytic effect. An improvement in sequential brain scans was detected in 2 other dogs in response to Dexamethasone, which was given in a double-blinded, cross-over controlled fashion. Computerized tomography clearly demonstrated the tumor in two cases.

Lung Scan and Shunted Childhood Hydrocephalus

Twenty‐six lung scans, using 1131macroaggregates of human serum albumin, were performed on twenty hydrocephalics with ventriculo‐atrial shunts.