A cavernous sinus lesion clinically responsive to steroids.

Tolosa Hunt syndrome (THS) is characterized by painful ophthalmoplegia secondary to idiopathic granulomatous inflammation of the cavernous sinus. The characteristic finding on MRI is an enhancing T1 isointense and T2 hypo- or hyperintense cavernous sinus mass lesion, which may result in focal narrowing of the ipsilateral internal carotid artery. Although the incidence is quite rare, it is a common diagnostic consideration in cases that present with multiple cranial neuropathies. However, the differential diagnosis for a unilateral cavernous sinus lesion in adults is broad and includes neoplastic, inflammatory (such as sarcoidosis and immunoglobulin G4-related disease [IgG4-RD]), infectious etiologies (such as syphilis and leprosy), as well as vascular lesions. We describe a patient presenting with neurologic symptoms referable to a persistent unilateral cavernous sinus MRI abnormality, initially thought to be consistent with Tolosa-Hunt syndrome, that was clinically but not radiographically responsive to steroids. Following reevaluation due to the presence of new symptoms, pathology revealed that the abnormality was most consistent with chordoma, a rare skull based tumor. In patients with a presumed diagnosis of Tolosa-Hunt syndrome, close clinical and radiographic follow-up is imperative, with early consideration for biopsy in patients that fail to respond to treatment both clinically and radiographically.

Hearing preservation after stereotactic radiosurgery for bilateral cerebellopontine angle meningiomas.

BACKGROUND: Preservation of cranial nerve function is critical in the management of patients with cerebellopontine angle (CPA) tumors. CASE REPORT: A 51-year-old woman with tinnitus and dizziness was discovered to have bilateral CPA dural-based masses extending into the internal auditory canals (IAC). Pre-operatively, the patient had normal hearing on the right (SRT, 5 dB; SDS 100% at 30 dB) and left (SRT, 10 dB; SDS 90% at 40 dB). The patient underwent two Leksell Gamma Knife (Elekta Instruments, Norcross, GA) radiosurgeries initially for the larger left-sided tumor, then one year later for the right. The margin dose for each tumor was 14 Gy. Six years after the first radiosurgery, the tumors have not progressed and she has retained normal hearing and facial function bilaterally. CONCLUSION: Preservation of cranial nerve function is generally possible after stereotactic radiosurgery of CPA meningiomas.

Seizure outcomes after stereotactic radiosurgery for cerebral arteriovenous malformations.

OBJECTIVES: To determine the effect of stereotactic radiosurgery on seizure outcomes for patients with intracerebral arteriovenous malformations (AVM). METHODS: Between May 1990 and December 1998, 65 patients with a history of single or recurrent seizures underwent AVM radiosurgery, had more than 1 year of follow-up, and sufficient data to record an Engel seizure frequency score. The authors reviewed their records and updated clinical information when necessary with direct patient contact. Follow-up ranged from 12 to 144 months (median, 48 months). Seizure frequency was compared before and after radiosurgery with the Engel Seizure Frequency Scoring System. RESULTS: Overall, 26 patients (51%) were seizure-free (aura-free) after radiosurgery at 3-year follow-up; 40 patients (78%) had an excellent outcome (non-disabling simple partial seizures only) at 3-year follow-up. Factors associated with seizure-free or excellent outcomes include a low seizure frequency score (<4) before radiosurgery and smaller size and diameter AVM. Twenty-three patients had intractable partial epilepsy prior to treatment. Twelve (52%) of 23 and 11 of 18 (61%) patients with medically intractable partial epilepsy had excellent outcomes at years 1 and 3. CONCLUSION: Overall, stereotactic radiosurgery improves seizure outcomes in the majority of patients and more than half of the patients with medically intractable partial epilepsy had an excellent seizure outcome after radiosurgery.

Does increased nerve length within the treatment volume improve trigeminal neuralgia radiosurgery? A prospective double-blind, randomized study.

PURPOSE: To test the hypothesis that increasing the nerve length within the treatment volume for trigeminal neuralgia radiosurgery would improve pain relief. METHODS AND MATERIALS: Eighty-seven patients with typical trigeminal neuralgia were randomized to undergo retrogasserian gamma knife radiosurgery (75 Gy maximal dose with 4-mm diameter collimators) using either one (n = 44) or two (n = 43) isocenters. The median follow-up was 26 months (range 1-36). RESULTS: Pain relief was complete in 57 patients (45 without medication and 12 with low-dose medication), partial in 15, and minimal in another 15 patients. The actuarial rate of obtaining complete pain relief (with or without medication) was 67.7% +/- 5.1%. The pain relief was identical for one- and two-isocenter radiosurgery. Pain relapsed in 30 of 72 responding patients. Facial numbness and mild and severe paresthesias developed in 8, 5, and 1 two-isocenter patients vs. 3, 4, and 0 one-isocenter patients, respectively (p = 0.23). Improved pain relief correlated with younger age (p = 0.025) and fewer prior procedures (p = 0.039) and complications (numbness or paresthesias) correlated with the nerve length irradiated (p = 0.018). CONCLUSIONS: Increasing the treatment volume to include a longer nerve length for trigeminal neuralgia radiosurgery does not significantly improve pain relief but may increase complications.

Management of cysts arising after radiosurgery to treat intracranial arteriovenous malformations.

OBJECTIVE: The proper treatment for patients with cyst formation after arteriovenous malformation radiosurgery is unknown. METHODS: The treatment of six patients who developed cysts after arteriovenous malformation radiosurgery is described. Four patients had undergone gamma knife radiosurgery (two patients developed cysts after repeat procedures), and two patients had undergone linear accelerator-based radiosurgery. The median prescription isodose volume at the time of the first radiosurgical procedure was 13.2 cm3 (range, 8.0-28.7 cm3). RESULTS: The cysts were discovered a median of 48 months (range, 24-89 mo) after radiosurgery. Three patients were originally without symptoms, and observation with serial imaging was performed; two of those patients developed symptoms 13 and 40 months later, whereas one patient has remained without symptoms for 51 months. Initial treatments for patients with symptomatic cysts included cyst aspiration (n = 3) and placement of a cystoperitoneal shunt (CPS) (n = 2). The median cyst volume was 14 cm3 (range, 4-63 cm3). Cyst recurrence occurred within 2 months for patients who underwent aspiration alone, necessitating placement of a CPS. Shunt placement eliminated the cysts for four patients, at a median follow-up time of 16 months (range, 9-27 mo). One patient's cyst persisted despite CPS placement, and cyst excision was performed. No morbidity occurred with any of the cyst treatments. CONCLUSION: Cyst formation after arteriovenous malformation radiosurgery may occur many years after the procedure. Although most symptomatic cysts can be effectively treated with CPSs, cyst excision may be necessary if the mass effect is not relieved with the less invasive approach.

High-dose trigeminal neuralgia radiosurgery associated with increased risk of trigeminal nerve dysfunction.

OBJECTIVE: Stereotactic radiosurgery is being used with more frequency in the management of patients with trigeminal neuralgia. To improve facial pain outcomes, many centers have increased the prescribed radiation dose to the trigeminal nerve. METHODS: Between April 1997 and December 1999, 68 patients underwent radiosurgery for trigeminal neuralgia with use of the Leksell gamma knife (Elekta Instruments, Norcross, GA) and a single 4-mm isocenter of radiation. Twenty-seven patients (40%) received 70 Gy (low dose) of irradiation and 41 patients (60%) received 90 Gy (high dose). The groups were similar with regard to age, sex, duration of pain, number of prior surgeries, and preexisting trigeminal deficits. The primary facial pain outcomes for analysis were excellent (pain-free, no medications) and good (pain-free, reduced medications). The mean length of follow-up after radiosurgery was 14.4 months (range, 2-36 mo). RESULTS: At last follow-up examination, 11 (41%) of the 27 patients with low-dose radiosurgery remained pain-free compared with 25 (61%) of the 41 patients with high-dose radiosurgery (P = 0.17). Additional surgery was performed in 12 low-dose patients (44%) and 8 high-dose patients (20%) (P = 0.05). High-dose radiosurgery was associated with an increased rate of permanent trigeminal nerve dysfunction (54% versus 15%, P = 0.003). Bothersome dysesthesias occurred in 13 high-dose patients (32%), whereas only 1 low-dose patient had this complication (P = 0.01). Three high-dose patients (8%) developed corneal numbness after radiosurgery. Pain recurred with more frequency in patients not developing trigeminal nerve dysfunction after radiosurgery (9 of 22 patients, 41 %) compared with those who sustained facial numbness, paresthesias, or dysesthesias (4 of 27 patients, 15%); however, the difference was not statistically significant (P = 0.08). CONCLUSION: Higher doses of radiation may correlate with better facial pain outcomes after radiosurgery for trigeminal neuralgia. However, the incidence of significant trigeminal nerve dysfunction is markedly increased after radiosurgery for patients receiving high-dose radiosurgery. Because of the nonselective nature of this ablative technique, dose prescription should be limited to less than 90 Gy.

Results of combined stereotactic radiosurgery and transarterial embolization for dural arteriovenous fistulas of the transverse and sigmoid sinuses.

OBJECT: Most dural arteriovenous fistulas (DAVFs) of the transverse and sigmoid sinuses do not have angiographically demonstrated features associated with intracranial hemorrhage and, therefore, may be treated nonsurgically. The authors report their experience using a staged combination of radiosurgery and transarterial embolization for treating DAVFs involving the transverse and sigmoid sinuses. METHODS: Between 1991 and 1998, 25 patients with DAVFs of the transverse and/or sigmoid sinuses were treated using stereotactic radiosurgery; 22 of these patients also underwent transarterial embolization. Two patients were lost to follow-up review. Clinical data, angiographic findings, and follow-up records for the remaining 23 patients were collected prospectively. The mean duration of clinical follow up after radiosurgery was 50 months (range 20-99 months). The 18 women and five men included in this series had a mean age of 57 years (range 33-79 years). Twenty-two (96%) of 23 patients presented with pulsatile tinnitus as the primary symptom; two patients had experienced an earlier intracerebral hemorrhage (ICH). Cognard classifications of the DAVFs included the following: I in 12 patients (52%), IIa in seven patients (30%), and III in four patients (17%). After treatment, symptoms resolved (20 patients) or improved significantly (two patients) in 96% of patients. One patient was clinically unchanged. No patient sustained an ICH or irradiation-related complication during the follow-up period. Seventeen patients underwent follow-up angiographic studies at a mean of 21 months after radiosurgery (range 11-38 months). Total or near-total obliteration (> 90%) was seen in 11 patients (65%), and more than a 50% reduction in six patients (35%). Two patients experienced recurrent tinnitus and underwent repeated radiosurgery and embolization at 21 and 38 months, respectively, after the first procedure. CONCLUSIONS: A staged combination of radiosurgery and transarterial embolization provides excellent symptom relief and a good angiographically verified cure rate for patients harboring low-risk DAVFs of the transverse and sigmoid sinuses. This combined approach is a safe and effective treatment strategy for patients without angiographically determined risk factors for hemorrhage and for elderly patients with significant comorbidities.

Fatal progression of posttraumatic dural arteriovenous fistulas refractory to multimodal therapy. Case report.

The authors report the case of a man who suffered from progressive, disseminated posttraumatic dural arteriovenous fistulas (DAVFs) resulting in death, despite aggressive endovascular, surgical, and radiosurgical treatment. This 31-year-old man was struck on the head while playing basketball. Two weeks later a soft, pulsatile mass developed at his vertex, and the man began to experience pulsatile tinnitus and progressive headaches. Magnetic resonance imaging and subsequent angiography revealed multiple AVFs in the scalp, calvaria, and dura, with drainage into the superior sagittal sinus. The patient was treated initially with transarterial embolization in five stages, followed by vertex craniotomy and surgical resection of the AVFs. However, multiple additional DAVFs developed over the bilateral convexities, the falx, and the tentorium. Subsequent treatment entailed 15 stages of transarterial embolization; seven stages of transvenous embolization, including complete occlusion of the sagittal sinus and partial occlusion of the straight sinus; three stages of stereotactic radiosurgery; and a second craniotomy with aggressive disconnection of the DAVFs. Unfortunately, the fistulas continued to progress, resulting in diffuse venous hypertension, multiple intracerebral hemorrhages in both hemispheres, and, ultimately, death nearly 5 years after the initial trauma. Endovascular, surgical, and radiosurgical treatments are successful in curing most patients with DAVFs. The failure of multimodal therapy and the fulminant progression and disseminated nature of this patient's disease are unique.

Cerebrovascular manifestations in 321 cases of hereditary hemorrhagic telangiectasia.

BACKGROUND AND PURPOSE: Patients with hereditary hemorrhagic telangiectasia (HHT) are at risk for developing cerebral vascular malformations and pulmonary arteriovenous fistulae. We assessed the risk of neurological dysfunction from these malformations and fistulae. METHODS: Three hundred twenty-one consecutive patients with HHT seen at a single institution over a 20-year period were studied. Any evidence of prior neurological symptoms or presence of an intracranial vascular malformation was recorded. All cases of possible cerebral arteriovenous malformation were confirmed by conventional arteriography. RESULTS: Twelve patients (3.7%) had a history of cerebral vascular malformations. Ten patients had arteriovenous malformations, 1 had a dural arteriovenous fistula, and 1 had a cavernous malformation. Seven patients (2.1%) presented with intracranial hemorrhage, 2 presented with seizures alone, and 3 were discovered incidentally. The average age at the time of symptomatic intracranial hemorrhage was 25.4 years. All patients with a history of intracranial hemorrhage were classified as Rankin grade I or II at a mean follow-up interval of 6.0 years. A history of cerebral infarction or transient ischemic attack was found in 29.6% of patients with HHT and a pulmonary arteriovenous fistula. CONCLUSIONS: The risk of intracranial hemorrhage is low among people with HHT. Furthermore, a majority of these patients have a good functional outcome after hemorrhage. The data do not suggest a compelling indication for routine screening of patients with HHT for asymptomatic cerebral vascular malformations. By comparison, pulmonary arteriovenous fistulae are a much more frequent cause of neurological symptoms in this population.

Stereotactic radiosurgery for recurrent central neurocytoma: case report.

OBJECTIVE AND IMPORTANCE: Neurocytomas are typically benign tumors that have high local control rates after gross total resection. Nevertheless, tumor recurrence is possible, and some patients have aggressive tumors. CLINICAL PRESENTATION: A 26-year-old woman had a recurrent, asymptomatic neurocytoma 3 years after gross total resection. INTERVENTION: The patient underwent stereotactic radiosurgery for the tumor recurrence. Thirty-four months later, the patient remained neurologically intact, and the tumor had decreased significantly in size. CONCLUSION: Radiosurgery may be a viable treatment option for patients with recurrent neurocytomas or for patients whose tumor resections were subtotal.

Meningioma radiosurgery: tumor control, outcomes, and complications among 190 consecutive patients.

OBJECTIVE: To determine local control (LC) and complication rates for patients with intracranial meningiomas who underwent radiosurgery. METHODS: One hundred ninety consecutive patients with 206 meningiomas underwent radiosurgery between 1990 and 1998. One hundred forty-seven tumors (77%) involved the cranial base. The median age at the time of radiosurgery was 58 years (range, 20-90 yr). There were 126 female patients (66%). One hundred twelve patients (59%) had undergone one or more previous operations (median, 1; range, 1-5). Twenty-two patients (12%) had either atypical (n = 13) or malignant (n = 9) tumors. The median prescription isodose volume was 8.2 cm(3) (range, 0.5-50.5 cm(3)), and the median tumor margin dose was 16 Gy (range, 12-36 Gy). The median imaging and clinical follow-up periods were 40 and 47 months, respectively. RESULTS: Overall survival rates for the entire cohort at 5 and 7 years were 82 and 82%, respectively; cause-specific survival rates at 5 and 7 years were 94 and 92%, respectively. The cause-specific survival rates at 5 years for patients with benign, atypical, and malignant tumors were 100, 76, and 0%, respectively (P < 0.0001). The 5-year LC rate was 89%, with 114 tumors (56%) decreasing in size. LC rates were correlated with tumor histological features (P < 0.0001); patients with benign tumors exhibited a 5-year LC rate of 93%, compared with 68 and 0% for patients with atypical or malignant meningiomas, respectively. No correlation was observed between radiation dose and LC rate. Twenty-four patients (13%) experienced treatment-related complications, including cranial nerve deficits (8%), symptomatic parenchymal changes (3%), internal carotid artery stenosis (1%), and symptomatic cyst formation (1%). Only six patients (3%) exhibited decreases in functional status that were directly related to radiosurgery. Tumor volume, tumor margin dose, or previous radiotherapy was not associated with the development of radiation-related complications. CONCLUSION: Radiosurgery is an effective management strategy for many patients with meningiomas. Patients with atypical or malignant tumors exhibit high recurrence rates despite the use of radiosurgery, and these patients continue to exhibit worse cause-specific survival rates despite aggressive treatment, including surgery, external-beam radiotherapy, and radiosurgery. Further study is needed to determine the tumor control and complication rates 10 years or more after meningioma radiosurgery.

Development of a cerebral arteriovenous malformation documented in an adult by serial angiography. Case report.

This 61-year-old man with a right-sided tentorial dural arteriovenous fistula (DAVF) was initially treated with staged stereotactic radiosurgery and transarterial embolization. Results of follow-up cerebral angiography performed 4 years later demonstrated complete obliteration of the dAVF and development of a previously undetected cerebellar arteriovenous malformation (AVM). The newly diagnosed AVM was treated with repeated stereotactic radiosurgery. This represents the first reported case of the development of a cerebral AVM documented in an adult by serial angiography.

Stereotactic radiosurgery for cavernous malformations.

OBJECT: The use of stereotactic radiosurgery to treat cerebral cavernous malformations (CMs) is controversial. To evaluate the efficacy and safety of CM radiosurgery, the authors reviewed the experience at the Mayo Clinic during the past 10 years. METHODS: Seventeen patients underwent radiosurgery for high-surgical-risk CMs in the following sites: thalamus/basal ganglia (four patients), brainstem (12 patients), and corpus callosum (one patient). All patients had experienced at least two documented hemorrhages before undergoing radiosurgery. Stereotactic magnetic resonance (MR) imaging was used for target localization in all cases. The median margin radiation dose was 18 Gy and the median maximum dose was 32 Gy. The median length of follow-up review following radiosurgery was 51 months. The annual hemorrhage rate during the 51 months preceding radiosurgery was 40.1%, compared with 8.8% in the first 2 years following radiosurgery and 2.9% thereafter. In 10 patients (59%) new neurological deficits developed that were associated with regions of increased signal on long-repetition time MR imaging performed a median of 8 months (range 5-16 months) after radiosurgery. Three patients recovered, giving the group a permanent radiation-related morbidity rate of 41%. Compared with 31 patients harboring arteriovenous malformations (AVMs) of sizes and in locations similar to those of the aforementioned CMs, who underwent radiosurgery during the same time period, the patients with CMs were more likely to experience radiation-related complications (any complication, 59% compared with 10%; p < 0.001; permanent complication, 41% compared with 10%; p = 0.02). CONCLUSIONS: It is impossible to conclude that radiosurgery protects patients with CMs against future hemorrhage risk based on the available data, although it appears that some reduction in the bleeding rate occurs after a latency interval of several years. The risk of radiation-related complications after radiosurgery to treat CMs is greater than that found after radiosurgery in AVMs, even when adjusting for lesion size and location and for radiation dose.

Radiation induced vascular injury after stereotactic radiosurgery for trigeminal neuralgia: case report.

BACKGROUND: Stereotactic radiosurgery is increasingly used for the treatment of medically unresponsive trigeminal neuralgia. CASE DESCRIPTION: We present the case of a 69-year-old man with trigeminal neuralgia who underwent stereotactic radiosurgery after a failed balloon compression procedure. The radiosurgery also failed to provide the patient with any significant pain relief, and microvascular decompression of the trigeminal nerve was performed 10 months later. At operation, two adjacent veins and the superior cerebellar artery were noted to have focal changes consistent with atheromatous disease. CONCLUSION: We postulate that the recent radiation exposure resulted in the observed vascular injury. As a result, patients having trigeminal neuralgia radiosurgery need to be followed carefully for possible delayed ischemic events secondary to radiation-induced vascular injury.

Occlusive hyperemia: a radiosurgical phenomenon?

OBJECTIVE: Causes of neurological deficits after arteriovenous malformation (AVM) radiosurgery, including hemorrhage, radiation injury, and delayed cyst formation, are described. CONCEPT: Occlusive hyperemia has been described as a reason for neurological deterioration after AVM resection. Thrombosis of draining veins or dural sinuses is thought to cause postoperative bleeding or neurological deficits secondary to venous hypertension. In a similar manner, local hemodynamic changes can occur in the brain adjacent to an AVM after radiosurgery if venous outflow is obstructed. Two patients are presented whose cases demonstrate this phenomenon. CONCLUSION: Patients can experience clinical worsening after AVM radiosurgery from premature thrombosis of draining veins. Local hemodynamic changes could explain why imaging changes thought to be radiation related occur more frequently after radiosurgery of AVMs than of tumors.

Gamma knife radiosurgery for skull base meningiomas.

Radiosurgery has been proven to be a safe and effective management strategy for skull base meningiomas either primarily or for tumor recurrence or progression after prior microsurgical resection. With its steep radiation falloff, radiosurgery provides long-term tumor growth control without the complications associated with conventional fractionated radiation therapy. Stereotactic MR imaging has allowed better definition of the tumor margin for precise multiisocenter conformal dose planning, and our current radiation dose prescription has decreased the incidence of new cranial nerve deficits after radiosurgery to less than 10%. Tumor growth control after radiosurgery remains greater than 90%; patients with subsequent growth typically have tumor outside the irradiated volume or a histologic diagnosis of atypical or malignant meningioma. Still, longer follow-up is needed to ensure that tumor growth control remains permanent after radiosurgery. For patients with large tumors of the skull base, radiosurgery can be part of a staged approach with microsurgery. Initially, the tumor is debulked without an attempt at resection involving the cranial nerves or basal vessels. Radiosurgery can then be performed for the small remaining tumor volume with little risk of cranial nerve deficits. Such multimodality treatment should result in reduced patient morbidity, with long-term tumor control.

The rationale and technique of staged-volume arteriovenous malformation radiosurgery.

PURPOSE: Stereotactic radiosurgery is an effective management strategy for properly selected arteriovenous malformation (AVM) patients. However, the risk of postradiosurgical radiation-related injury generally limits this procedure to patients with AVMs of an average diameter of 3 cm or less. Radiosurgery of large AVMs in a planned staged fashion was undertaken to limit the radiation exposure to the surrounding normal brain. METHODS AND MATERIALS: Between April 1997 and December 1999, 10 patients with a median AVM volume of 17.4 cm(3) (range, 7.4-53.3 cm(3)) underwent staged-volume radiosurgery (23 procedures). At the first radiosurgical procedure, the total volume of the AVM is estimated and a dose plan calculated that covers 10 cm(3)-15 cm(3), or one-half the nidus volume if the AVM is critically located (brainstem, thalamus, or basal ganglia). At 6-month intervals thereafter, radiosurgery was repeated to different portions of the AVM with the previous dose plan(s) being re-created utilizing intracranial landmarks to minimize radiation overlap. Radiosurgical procedures were continued until the entire malformation has been irradiated. RESULTS: The radiation dosimetry of staged-volume AVM radiosurgery was compared to hypothetical single-session procedures for the 10 patients. Staged-volume radiosurgery decreased the 12-Gy volume by an average of 11.1% (range, 4.9-21%) (p < 0.001). The non-AVM 12-Gy volume was reduced by an average of 27.2% (range, 12.5-51.3%) (p < 0.001). DISCUSSION: Staged-volume radiosurgery of large AVMs results in less radiation exposure to the adjacent brain. Further follow-up is needed to determine whether this technique provides a high rate of AVM obliteration while maintaining an acceptable rate of radiation-related complications.

Stereotactic radiosurgery for hemangioblastomas of the brain.

OBJECTIVE: To assess the effectiveness of stereotactic radiosurgery in achieving tumor control and improving survival in patients with hemangioblastoma, we evaluated results from patients who were managed at the University of Pittsburgh and the Mayo Clinic. PATIENTS AND METHODS: Twenty-seven patients with 29 hemangioblastomas had stereotactic radiosurgery over a 10 year interval. The mean patient age was 32 years (range, 14-75 years). The tumor volumes varied from 0.36 to 27 ml (mean, 3.2 ml), and the mean tumor margin dose was 16 Gy (range, 11.7-20). Clinical and neuroimaging follow-up was obtained for all patients between 0.5 and 9 years (mean, 4 years) after radiosurgery. RESULTS: At this assessment, 21 patients (79%) were alive and six (21%) had died. The median survival after radiosurgery was 6.5 years (actuarial 5 year survival = 75.1 +/- 11.5%). The median survival from the initial diagnosis was 15 years. Twenty two of 29 evaluable tumors were controlled locally. The two-year actuarial control rate was 84.5 +/- 7.1% and at five years, 75.2 +/- 8.9%. Multivariate testing of factors affecting good outcome indicated that smaller tumor volume and higher radiosurgical dose (> 18 Gy) were significant. CONCLUSION: For small to moderate size hemangioblastomas, multiple or recurrent tumors, and for patients who are not surgical candidates, radiosurgery is a safe and effective option to control disease and improve survival.

A theory on the natural history of colloid cysts of the third ventricle.

OBJECTIVE: Patients with third ventricular colloid cysts typically are diagnosed when they develop symptoms related to cerebrospinal fluid (CSF) obstruction at the foramen of Monro. However, the clinical and neuroimaging characteristics related to symptom development are poorly understood. METHODS: From January 1974 to June 1998, 155 patients with newly diagnosed colloid cysts were managed at our center. Eighty-seven patients (56%) were thought to have tumor-related symptoms, and they underwent surgery (resection, n = 74; ventriculoperitoneal shunting, n = 11; stereotactic aspiration, n = 2). Sixty-eight patients (44%) had colloid cysts thought to be asymptomatic, and observation with serial neuroimaging was recommended. Recursive partitioning was used to examine the association of patient and tumor characteristics with the development of cyst-related symptoms. RESULTS: Univariate analysis comparing symptomatic and asymptomatic patients revealed four factors associated with cyst-related symptoms: 1) younger patient age (44 yr versus 57 yr; P < 0.001); 2) cyst size (13 mm versus 8 mm; P < 0.001); 3) ventricular dilation (83% versus 31%; P < 0.001); and 4) increased signal on T2-weighted magnetic resonance images (44% versus 8%; P = 0.001). All four variables remained significant in a multivariate logistic regression model: patient age (P = 0.04; odds ratio, 1.0); cyst size (P = 0.04; odds ratio, 1.2); ventricular dilation (P = 0.02, odds ratio, 7.2); and increased signal on T2-weighted magnetic resonance images (P = 0.04; odds ratio, 2.7). The most significant variable was ventriculomegaly (yes versus no). Patients with normal-sized ventricles (n = 62) were further categorized by cyst size (< or = 10 mm versus > 10 mm). For patients with enlarged ventricles (n = 93), patient age (< or = 50 yr versus > 50 yr) was the most important variable. Patients older than 50 years also were split with respect to cyst size; patients aged 50 years or younger with enlarged ventricles were not affected by cyst size. The percentage of patients with cyst-related symptoms was 12, 50, and 85% in the three final patient classes, respectively. Multivariate analysis including the patient classes resulted in removal of the other significant variables from the model, whereas the patient classes remained significant (P < 0.0001; odds ratio, 6.3) for predicting patients with cyst-related symptoms. CONCLUSION: The patient and neuroimaging characteristics of the different patient classes support a theory on the natural history of colloid cysts. Patients with third ventricular colloid cysts become symptomatic when the tumor enlarges rapidly, causing CSF obstruction, ventriculomegaly, and increased intracranial pressure. Some cysts enlarge more gradually, however, allowing the patient to accommodate the enlarging mass without disruption of CSF flow, and the patient remains asymptomatic. In these cases, if the cyst stops growing, the patient can maintain a steady state between CSF production and absorption and may not require neurosurgical intervention.

Stereotactic radiosurgery for tumor-related trigeminal pain.

OBJECTIVE: Between 1 and 6% of patients who are diagnosed with facial pain syndromes have tumors that involve the trigeminal nerve. We report the effects of stereotactic radiosurgery on tumor-related trigeminal pain. METHODS: We reviewed results, from a prospective database, for 24 consecutive patients with cranial base tumors and either trigeminal neuralgia (n = 9) or painful trigeminal neuropathy (n = 15) who underwent stereotactic radiosurgery during an 8-year period. The tumor was the radiosurgical target for these patients (not the trigeminal nerve or ganglion). The median clinical follow-up period after radiosurgery was 45 months (range, 12-90 mo); the median neuroimaging follow-up period was 36 months (range, 5-86 mo). RESULTS: There were 20 women and 3 men, with an average age of 57 years (range, 33-79 yr). One patient had bilateral facial pain and underwent staged radiosurgery. Pathological classification indicated 16 meningiomas and 8 malignant cranial base tumors (adenoid cystic carcinoma, n = 6; squamous cell carcinoma, n = 2). Twelve of 24 patients (50%) were initially free of pain, and another 11 patients (46%) reported that they experienced significant improvements in their trigeminal pain syndromes after radiosurgery. The tumor histological type, quality of facial pain, preexisting facial numbness, and marginal and maximal radiation doses were not related to postradiosurgical facial pain outcomes. Three patients with malignant cranial base carcinomas developed recurrent facial pain, 1 to 9 months after radiosurgery, which was related to tumor progression outside the irradiated volume. One patient (4%) developed new partial V2 numbness after radiosurgery. CONCLUSION: Radiosurgery proved to be effective in improving tumor-related trigeminal pain for the majority of patients with either benign or malignant cranial base tumors. Recurrence of trigeminal pain is frequent for patients with malignant cranial base carcinomas and is related to tumor progression.