Gamma knife radiosurgery for trigeminal neuralgia: dose-volume histograms of the brainstem and trigeminal nerve.

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.

Gamma knife radiosurgery for primary management for trigeminal neuralgia.

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.

Surgical treatment of trigeminal neuralgia.

Patients with medically intractable trigeminal neuralgia characterized by paroxysmal, triggered, trigeminally distributed pain are excellent candidates for neurosurgical intervention, which can not only relieve the pain of trigeminal neuralgia, but also eliminate the unpleasant side effects of medicines used to treat it. The two major neurosurgical choices are percutaneous denervation and microvascular decompression (MVD). Percutaneous denervation is done best when the surgeon has available radiofrequency and glycerol and uses one, the other, or both depending on technical circumstances that pertain to each patient. The percutaneous denervation is less likely than MVD to cause death, stroke, facial weakness, or hearing loss, but more likely to be associated with recurrence or dysesthesias. Patients with multiple sclerosis, medical illness, or who are elderly are much better candidates for percutaneous denervation. For any patient, a number of other factors also must be considered before deciding on a particular procedure. These include response to previous interventions, ability to tolerate carbamazepine, risk tolerance for various complications, preference regarding duration of hospital stay and postoperative recovery, presence of pain outside the trigeminal distribution, and findings on a high resolution magnetic resonance imaging (MRI) scan.

Analgesia and sedation during percutaneous radiofrequency electrocoagulation for trigeminal neuralgia.

Patient comfort during percutaneous radiofrequency electrocoagulation for trigeminal neuralgia provides better working conditions for the surgeon and makes the patient more willing to return if a second procedure is necessary. This study evaluates five different regimens for analgesia and sedation including the standard of fentanyl and droperidol (Group A) and four other regimens, each containing midazolam. In a sixth group, droperidol was assessed for its antiemetic effects. Patients were medicated as follows: Group B, low-dose midazolam (3.0 mg average); Group C, low-dose midazolam (2.5 mg average) and oral diazepam (7.5 mg average) just before the procedure; Group D, high-dose midazolam (5.5 mg average); and Group E, high-dose midazolam (5.1 mg average) and oral diazepam. Medications were titrated to induce mild sedation in Groups A, B, and C and heavier sedation in Groups D and E. All patients received fentanyl and small doses of intravenous methohexital just before the cannula penetrated the foramen ovale and before radiofrequency electrocoagulation. At least 2 weeks later, patients reported their level of discomfort during the procedure and their recollection of the procedure on a 0 to 10 scale. In another group of 96 patients, 1.25 mg of droperidol was given in addition to the medications described for Groups D and E. There was a statistically significant improvement in comfort in Groups C, D, and E and added amnesia in Groups D and E. Vomiting occurred in none of the patients medicated with droperidol and in 5 of 143 patients who did not receive droperidol.(ABSTRACT TRUNCATED AT 250 WORDS)

Bilateral trigeminal neuralgia.

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.

Trigeminal neuralgia and multiple sclerosis.

In a series of patients with trigeminal neuralgia (TN) who were treated with radiofrequency electrocoagulation of the gasserian ganglion and retrogasserian rootlets, either alone or with glycerol, 16 patients with TN and multiple sclerosis (TNMS) are compared with 219 patients with TN without MS. Patients with TNMS were younger and more likely to have bilateral facial pain than those with TN alone. Probability of ipsilateral recurrence was calculated on the basis of Kaplan and Meier product-limit estimates and showed no significant differences in the two groups.

Treatment of lower extremity reflex sympathetic dystrophy with continuous intrathecal morphine infusion.

Continuous intrathecal morphine infusion has been used in 3 patients with refractory lower extremity reflex sympathetic dystrophy syndromes. Two patients have experienced prolonged significant benefit.

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%).

Management of extracranial carotid stenosis and intracranial aneurysms.

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.

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.

Period of risk for recurrence in medulloblastoma.

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.

Adjuvant nitrosourea therapy for glioblastoma.

An attempt was made to evaluate the potential advantages of chemotherapy in the treatment of 62 patients with glioblastoma. Twenty-four of the 62 patients received adjuvant nitrosourea chemotherapy with carmustine (BCNU), lomustine (CCNU), or semustine (methyl CCCNU) in addition to surgery and radiotherapy. Thirty-three of the 62 patients were involved in a controlled, prospective, randomly allocated study. Quality or quantity of survival was not prolonged in patients who received chemotherapy. Age greater than 64 years, a severe postoperative neurological deficit, or the onset of symptoms less than 12 months prior to surgery were associated with a worse prognosis. The valid evaluation of the effect of a form of treatment on survival in patients with glioblastoma is contingent on the regorous avoidance of preselected factors that may predispose the treated group to a more favorable prognosis.

Computerized tomography correlated with CSF protein concentrations.

The authors present a case of hydrocephalus complicated by ventriculitis in which it was possible to correlate the numerical printout of sequential computerized tomograms (CT-Scans) with cerebrospinal fluid protein concentrations obtained by direct ventricular puncture. Different protein levels were unambiguously associated with changes in the absorption numbers on the scan but they did not bear a simple linear relationship to one another. The value of the numerical printout in diagnosis and follow-up is discussed.