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Ronald Brisman

Object. The author presents a large series of patients with idiopathic trigeminal neuralgia (TN) who were treated with gamma knife surgery (GKS), at a maximum dose of 75 to 76.8 Gy, and followed up in a nearly uniform manner for up to 4.6 years.

Methods. Two hundred ninety-three patients were treated and followed up for at least 6 months (range 0.4–4.6 years, median 1.9 years). At the final follow-up review, there was complete (100%) pain relief without medicines in 64 patients (21.8%), 90% or greater relief with or without small doses of medicines in 86 (29.4%), between 75 and 89% relief in 31 (10.6%), between 50 and 74% relief in 19 (6.5%), and less than 50% relief in 23 patients (7.8%). Recurrent pain requiring a second procedure occurred in 70 patients (23.9%). Kaplan—Meier analysis showed that 100%, 90% or greater, and 50% or greater pain relief was obtained and maintained for 3.5 to 4.1 years in 5.6 , 23.7, and 50.4% patients, respectively. Of 31 patients who described pain relief ranging from 75 to 89%, 80% of patients described it as good and 10% as excellent; of 17 patients who reported between 50 and 74% pain relief, 53% described it as good and none as excellent (p = 0.014). Dysesthesia scores greater than 5 (scale of 0–10, in which a score of 10 represents excruciating pain) occurred in four (3.2%) of 126 patients who had not undergone prior surgery; all these patients obtained either good or excellent relief from TN pain. There were 36 patients in whom the TN had atypical features; these patients were less likely to attain at least 50% or at least 90% pain relief compared with those without atypical TN features (p = 0.001).

Conclusions. Gamma knife surgery is a safe and effective way to relieve TN. Patients who attain between 75 and 89% pain relief are much more likely to describe this outcome as good or excellent than those who attain between 50 and 74% pain relief.

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Ronald Brisman

Object. The purpose of this study was to assess the efficacy of gamma knife radiosurgery (GKS) as the primary rather than secondary management for trigeminal neuralgia.

Methods. Eighty-two patients underwent GKS as their first neurosurgical intervention (Group A), and 90 patients underwent GKS following a different procedure (Group B). All GKS patients were treated with a maximum dose of 75 Gy. The single 4-mm isocenter was placed close to the junction of the trigeminal nerve and the brainstem. Six-month follow up was available for 126 patients and 12-month follow up for 84 patients.

Excellent (no pain and no medicine) or good (at least 50% reduction in pain and less medicine) relief was more likely to occur in Group A than in Group B patients 6 and 12 months following GKS for trigeminal neuralgia (p = 0.058). Excellent or good results were also more likely in patients with trigeminal neuralgia without multiple sclerosis (MS) (p = 0.042). The number and type of procedures performed prior to GKS, the interval between the last procedure and GKS, and the interval from first symptom to GKS (within Groups A and B) did not affect 6-month outcome. The interval between first symptom and GKS was shorter in Group A patients without MS (87 months) than in Group B (148 months; p < 0.004). There were no significant differences between Group A and B patients with regard to sex, age, or laterality.

Conclusions. Patients with trigeminal neuralgia who are treated with GKS as primary management have better pain relief than those treated with GKS as secondary management. Patients are more likely to have pain relief if they do not have MS.

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Ronald Brisman and R. Mooij

Object. The purpose of this study was to assess the relationship between the volume of brainstem that receives 20% or more of the maximum dose (VB20) and the volume of the trigeminal nerve that receives 50% or more of the maximum dose (VT50) on clinical outcome following gamma knife radiosurgery (GKS) for trigeminal neuralgia (TN).

Methods. Patients with TN were treated with a single 4-mm isocenter with a maximum dose of 75 Gy directed at the trigeminal nerve close to where it leaves the brainstem. The VB20 and VT50, as determined on dose—volume histograms, were correlated with clinical outcomes at 6 and 12 months, laterality, presence of multiple sclerosis (MS), and each other.

At 6 months excellent pain relief (no pain or required medicine) was achieved in 27 of 48 patients (p = 0.009) when VB20 was greater than or equal to 20 mm3 and in 25 of 78 when VB20 was less than 20 mm3, when all patients are considered. At 12 months excellent pain relief was achieved in 16 of 32 patients (p = 0.038) when VB20 was greater than or equal to 20 mm3 and in 14 of 52 when VB20 less than 20 mm3, when all patients are considered. When VB20 was less than 20 mm3 in MS patients, five of 21 had an excellent result at 6 months and two of 13 at 12 months. The VB20 was 20 mm3 or more in 38 of 64 on the right side and in eight of 41 on the left side (p < 0.001) in patients with TN and without MS. There is a difference between left and right dose—volume histograms even when the same isodose is placed on the surface of the brainstem.

The VB20 was 20 mm3 or more in 45 of 105 patients with TN and without MS but in only three of 21 patients with TN and MS (p = 0.014). There was an inverse relationship between VB20 and VT50 (p = 0.01).

Conclusions. Isocenter proximity to the brainstem, as reflected in a higher VB20, is associated with a greater chance of excellent outcome at 6 and 12 months. Worse results in patients with TN and MS may be partly explained by a lower VB20.

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Ronald Brisman

✓ Bilateral trigeminal neuralgia occurred in 32 (11.9%) of 269 consecutive patients who were treated with radiofrequency electrocoagulation (RFE). This is a higher incidence than has been reported before and may be explained by the prospective nature of the present study, the long follow-up period, and the inclusion of patients with mild bilateral symptoms. Multiple sclerosis is the most common predisposing factor and occurred in 18% of those with bilateral trigeminal neuralgia. Although patients with bilateral trigeminal neuralgia were more likely to have had prior surgery than those with unilateral neuralgia, they did not have a higher recurrence rate following treatment. Percutaneous RFE of the retrogasserian rootlets and gasserian ganglion, with or without glycerol, is effective in managing patients whose pain is intractable to medical therapy. The preservation of most trigeminal sensory and motor functions, the low morbidity rate, and the ability to repeat the procedure are particularly advantageous for patients with bilateral involvement.

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Jack Stern, Margaret Whelan, Ronald Brisman and James W. Correll

✓ Twenty patients with extracranial carotid stenosis and intracranial aneurysms are reviewed. Fifteen of these patients had transient ischemic attacks (TIA's) and incidental aneurysms. The other five presented with symptoms referrable to an aneurysm, and angiography revealed significant carotid stenosis. None of the patients who presented with TIA's and underwent endarterectomy suffered subarachnoid hemorrhage. However, those patients who presented with symptoms referrable to an aneurysm and underwent endarterectomy seem to be at greater risk for subarachnoid hemorrhage.

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Donald O. Quest, Ronald Brisman, Joao L. Antunes and Edgar M. Housepian

✓ Ninety-nine patients with medulloblastoma who received surgery and radiotherapy, and had a statistically sufficient follow-up period were analyzed for factors influencing survival and the relevance of the “period of risk for recurrence” hypothesis. This postulate states that the period of risk for recurrence of a congenital tumor is equal to the age at presentation of illness plus 9 months' gestational time. The assumption is made that a tumor of embryonic origin will become manifest after a period of time determined by its inherent rate of growth and that tumor cells surviving treatment will multiply and present with recurrence in an equal period of time. Ten of 43 patients survived the period of risk, a presumed cure rate of 23%. None of these patients has subsequently developed evidence of tumor recurrence. Older patients at initial surgery had a somewhat greater survival rate for the first 5 years after treatment (10 of 26 older patients (38%) versus 15 of 54 younger patients (28%)), but by 10 years there was no appreciable difference in survival rates between those over 16 years of age and those younger. The beneficial effect of total neuraxis megavoltage radiotherapy is indicated by the improved 5-year survival rate from 9 of 41 patients (22%) to 16 of 39 patients (41%) with the newer techniques.

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Ronald Brisman, Darrell S. Buchanan and Harold Rosegay

✓ A prospective controlled study was done to evaluate technician reliability in measuring midline cerebral shifts by computerized (Midliner) and standard A-mode echoencephalography. Thirteen of 16 (81%) verified shifts were correctly predicted by the Midliner, while only five of 14 (36%) shifts were correctly noted by the standard echoencephalograms. Two false negatives occurred with 2 mm Midliner shifts. The computerized echoencephalogram is a simple and effective instrument for determining midline shifts even when used by minimally trained paramedical personnel, but its reliability is limited when it shows a 1.5 to 2 mm shift or an unsatisfactory tracing.

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Ronald Brisman, Sanford Schneider and Sidney Carter

✓ A simplified technique for subarachnoid cerebrospinal fluid infusion of Ringer's lactate is described and evaluated as a method for determining shunt patency. An infusion index (change in pressure divided by volume infused) of 11 or greater is highly suggestive of shunt occlusion while an index of 6 or less strongly suggests a patent shunt. Further accuracy results when a baseline index and pressure-volume-time curve are obtained at a time of known shunt patency and compared with subsequent infusions. Using these criteria, the proper evaluation of shunt patency has been made in 18 out of 19 verified shunt problems.

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Ronald Brisman and Jerry Mendell

✓ The relationship between brain tumor location and thromboembolism was studied by a retrospective review of autopsy and clinical material. Patients with suprasellar tumors had a higher incidence of thromboembolic complications than those with tumors in other locations. An associated derangement of hypothalamic function is suggested as predisposing to thromboembolism.