Magnetic resonance imaging signal characteristics associated with prognosis of skull base chordoma after gamma knife radiosurgery.

OBJECTIVE: To investigate the association between the magnetic resonance imaging (MRI) signal characteristics of skull base chordoma and radiosurgical outcomes. METHODS: Twenty-four patients with skull base chordomas treated with Gamma Knife radiosurgery (GKRS) after previous surgical resection were retrospectively (2001-2021) examined. Pre-GKRS MRIs were analyzed for RT2 (tumor-to-brainstem signal intensity ratio on T2-weighted imaging), RCE (tumor-to-brainstem signal intensity ratio on contrast-enhanced T1-weighted imaging), and mean apparent diffusion coefficient (ADC). Correlations of the parameters with patient survival and local tumor progression were made by using Cox regression and Kaplan-Meier analyses. RESULTS: During a median follow-up of 46 months after GKRS, 9 patients died with significantly more local tumor progression events (median number: 2 vs 0, P = .012) than did 15 alive patients. On multivariable analysis, higher mean ADC was associated with longer patient survival (P = .016) after GKRS. The actuarial 5-year overall survival rates were 88.9% versus 54.7% for chordomas with an ADC of ≥ 1270 × 10-6 mm2/s versus < 1270 × 10-6 mm2/s. RT2 < 1.5 (P = .038) and RCE > 1.57 (P = .022) were associated with a lower probability of local tumor control. CONCLUSION: Lower mean ADC values are associated with shorter patient survival in skull base chordomas after GKRS. Diffusion-weighted imaging may help in GKRS planning and outcome prediction for these patients.

Is it advisable to perform radiosurgery for EGFR-TKI-controlled brain metastases? A retrospective study of the role of radiosurgery in lung cancer treatment.

PURPOSE: Given the availability of TKIs with high central nervous system efficacy, the question arises as to whether upfront SRS provides additional clinical benefits. The goal of this study was to characterize the clinical outcomes of SRS as salvage therapy for TKI-uncontrolled BMs. METHODS: This retrospective study included EGFR-mutant NSCLC patients presenting BMs at the time of primary tumor diagnosis. BMs were categorized into three subgroups, referred to as "Nature of TKI-treated BMs", "TKI-controlled brain metastases ± SRS", and "SRS salvage therapy". The first subgroup analysis characterized the effects of TKIs on tumor behavior. In the second subgroup, we compared outcomes of TKI-controlled BMs treated with TKI alone versus those treated with combined TKI-SRS therapy. The third subgroup characterized the outcomes of TKI-uncontrolled BMs treated with SRS as salvage therapy Clinical outcomes include local and distant tumor control. RESULTS: This study included 106 patients with a total of 683 BMs. TKI treatment achieved control in 63% of local tumors at 24 months. Among the TKI-controlled BMs, local tumor control was significantly higher in the combined TKI-SRS group (93%) than in the TKI-alone group (65%) at 24 months (p < 0.001). No differences were observed between the two groups in terms of distant tumor control (p = 0.832). In dealing with TKI-uncontrolled BMs, salvage SRS achieved local tumor control in 58% of BMs at 24 months. CONCLUSIONS: While upfront TKI alone proved highly effective in BM control, this study also demonstrated the outcomes of SRS when implemented concurrently with TKI or as salvage therapy for TKI-uncontrolled BMs. This study also presents a strategy of the precise timing and targeting of SRS to lesions in progression.

Sinovenous outflow in lateral sinus dural arteriovenous fistulas after stereotactic radiosurgery: a retrospective longitudinal imaging study.

PURPOSE: To investigate sinovenous outflow restriction (SOR) in lateral sinus dural arteriovenous fistulas (LSDAVFs) after Gamma Knife radiosurgery (GKRS) and its association with complete obliteration. METHODS: We retrospectively (1995-2019) enrolled 39 patients with LSDAVFs who had undergone GKRS alone and evaluated their angiography and magnetic resonance imaging (MRI) before and after GKRS. The LS conduits ipsilateral and contralateral to the DAVFs were scored using a 5-point scoring system, with scores ranging from 0 (total occlusion) to 4 (fully patent). SOR was defined by a conduit score < 2. Demographics, imaging features, and outcomes were compared between patients with and without ipsilateral SOR after GKRS. Logistic regression analysis was performed to estimate the odds ratio (OR) for obliteration with the imaging findings. RESULTS: After a median angiographic follow-up of 28 months for the 39 patients, the ipsilateral LS became more restrictive (median conduit score before and after GKRS: 2 vs. 1, p = .011). Twenty-one patients with ipsilateral SOR after GKRS had a significantly lower obliteration rate (52.4% vs. 94.4%, p = .005) than those without SOR. Follow-up SOR was independently associated with a lower obliteration rate (OR 0.05, p = .017) after adjustment for age, cortical venous reflux, and absent sinus flow void on MRI. CONCLUSION: This study demonstrates a restrictive change of outflow in LSDAVFs after GKRS and a lower obliteration rate in patients with SOR. Follow-up imaging for SOR may help predict outcomes of these patients.

Does the Diffuseness of the Nidus Affect the Outcome of Stereotactic Radiosurgery in Patients with Unruptured Cerebral Arteriovenous Malformations?

BACKGROUND: We proposed an algorithm to automate the components within the identification of components within the nidus of cerebral arteriovenous malformations (AVMs) which may be used to analyze the relationship between its diffuseness and treatment outcomes following stereotactic radiosurgery (SRS). OBJECTIVES: to determine the impact of the diffuseness of the AVM nidus on SRS outcomes. METHODS: This study conducted regular follow-ups of 209 patients with unruptured AVMs who underwent SRS. The diffuseness of the AVM nidus was estimated by quantifying the proportions of vascular nidal component, brain parenchyma, and cerebrospinal fluid in T2-weighted MRIs. We used Cox regression analysis to characterize the association between nidal diffuseness and treatment outcomes in terms of obliteration rate and radiation-induced change (RICs) rate following SRS. RESULTS: The median AVM volume was 20.7 cm3. The median duration of imaging follow-up was 51 months after SRS. The overall AVM obliteration rate was 68.4%. RICs were identified in 156 of the 209 patients (74.6%). The median proportions of the nidus of AVM and brain parenchyma components within the prescription isodose range were 30.2 and 52.2%, respectively. Cox regression multivariate analysis revealed that the only factor associated with AVM obliteration rate after SRS was AVM volume. However, a larger AVM volume (>20 mL) and a larger proportion of brain parenchyma (>50%) within the prescription isodose range were both correlated with a higher RIC rate following SRS. CONCLUSIONS: The diffuseness of the nidus indeed appears to affect the RIC rate following SRS in patients with unruptured AVMs.

Lateral Sinus Dural Arteriovenous Fistulas: Sinovenous Outflow Restriction Outweighs Cortical Venous Reflux as a Parameter Associated with Hemorrhage.

Purpose To investigate whether sinovenous outflow restriction (SOR) is more strongly associated with hemorrhage than cortical venous reflux (CVR) in patients with lateral sinus dural arteriovenous fistulas (DAVFs). Materials and Methods An institutional review board approved this retrospective study and waiver of informed consent was obtained. From 1995 to 2016, 163 cases of lateral sinus DAVFs were included and divided into hemorrhagic and nonhemorrhagic groups based on initial presentation. Their angiograms and magnetic resonance images were evaluated, with two evaluators independently grading CVR and SOR. The SOR was scored as the combined conduit score (CCS), ranging from zero (total occlusion) to 8 (fully patent). The CVR and CCS of the hemorrhagic and nonhemorrhagic groups were compared. Logistic regression models were established for both the CVR and CCS to compare their performances in discriminating DAVF hemorrhage. Results Sinovenous outflow was significantly more restrictive (lower median CCS) in the hemorrhagic group than in the nonhemorrhagic group (1 vs 6.5; P < .001). A CCS of less than or equal to 2 best discriminated between the groups with a sensitivity of 90.0% and a specificity of 88.1%. The CCS model had a higher discriminative performance than did the CVR model (area under the curve, 0.933 vs 0.843; P = .018). Conclusion The CCS grading system semiquantifies SOR. SOR may represent a stronger risk factor associated with hemorrhage in patients with lateral sinus DAVFs than does CVR, and thus may offer guidance in therapeutic decision making. © RSNA, 2017.

Shortened Cerebral Circulation Time Predicts Resistance to Obliteration in High-Flow Brain Arteriovenous Malformations After Stereotactic Radiosurgery.

BACKGROUND AND OBJECTIVES: Treatment selection for brain arteriovenous malformations (BAVMs) is complicated by BAVM size, location, and hemodynamics. Quantitative digital subtraction angiography is used to quantify the hemodynamic impact of BAVMs on cerebral circulation. This study investigated the association between cerebral circulation time and the complete obliteration (CO) rate of BAVMs after stereotactic radiosurgery (SRS). METHODS: We analyzed the data of 143 patients who underwent SRS for BAVMs between January 2011 and December 2019 in our institute. Their pre-SRS magnetic resonance imaging and angiography images were analyzed to acquire BAVM characteristics and quantitative digital subtraction angiography parameters. Modified cerebral circulation time (mCCT) was defined as the time difference between the bolus arrival time of the ipsilateral cavernous internal carotid artery and that of the parietal vein, as determined from the lateral view of images obtained using digital subtraction angiography. Cox regression with hazard ratios and Kaplan-Meier analyses were conducted to determine the associations between the parameters and BAVM CO after SRS. RESULTS: Of the 143 patients, 101 (70.6%) achieved BAVM CO. According to the multivariate analyses, an increased mCCT (hazard ratio: 1.24, P = .041) was the independent factor associated with BAVM CO after adjustment for age, sex, hemorrhagic presentation, a BAVM volume of >5 cm3, and a margin dose of >18 Gy. Individuals with an mCCT of ≤2.32 s had a lower 36-month probability of BAVM CO than did those with an mCCT of >2.32 s (44.1% ± 6.8% vs 63.3% ± 5.6%, P = .034). CONCLUSION: The hemodynamic impact of high-flow BAVM demonstrated by a shortened mCCT is associated with a lower BAVM CO rate after SRS.

Imaging Markers Associated With Radiation-Induced Changes in Brain Arteriovenous Malformations After Radiosurgery.

BACKGROUND: Radiation-induced changes (RICs) in brain tissue, seen as increased perinidal T2-weighted hyperintensity on MRI, are commonly observed in patients with brain arteriovenous malformations (BAVMs) within 2 years after Gamma Knife (Elekta) radiosurgery (GKRS). OBJECTIVE: To explore the imaging markers associated with RICs in patients with BAVMs. METHODS: We retrospectively included 106 treatment-naïve patients with BAVMs who received GKRS alone between 2011 and 2018 and had ≥24 months of clinical and MRI follow-up. Pre-GKRS angiography and MRIs were analyzed for morphological characteristics and quantitative digital subtraction angiography parameters. RIC severity was categorized as mild (grade I), moderate (grade II), or severe (grade III). Firth logistic regression analysis was conducted to determine the associations between the parameters and RICs. RESULTS: Among the 106 patients, 83 (78.3%) developed RICs, with 16 categorized as grade I, 62 as grade II, and 5 as grade III. RICs were symptomatic in 19 patients (17.9%). In multivariable models, BAVMs with a volume of >5 cm3 (odds ratio [OR]: 4.322, P = .024) and neoangiogenesis on angiography before treatment (OR: 3.846, P = .029), and thrombus within nidus or drainage vein on follow-up MRI (OR: 3.679, P = .001) were independently associated with grade II or III RICs. Symptomatic RICs were more likely to develop in basal ganglia or brainstem. CONCLUSION: Large BAVMs and neoangiogenesis were associated with moderate to severe RICs in treatment-naïve patients with BAVMs. Our findings may assist with the complication risk assessment for these patients.

Outflow Patency Correlates with Radiosurgical Outcomes of Lateral Sinus Dural Arteriovenous Fistula.

OBJECTIVE: To explore the impact of outflow patency on radiosurgical outcomes of lateral sinus dural arteriovenous fistulas (DAVFs). METHODS: We retrospectively examined 83 lateral sinus DAVFs treated with Gamma Knife radiosurgery (GKRS) between 1995 and 2020. Two neuroradiologists blinded to the therapeutic outcomes served as imaging evaluators on pre-GKRS digital subtraction angiography and magnetic resonance images. The sinovenous outflow of lateral sinus DAVF was scored using combined conduit score (CCS), ranging from 0 (total occlusion) to 8 (full patency). The patients' follow-up magnetic resonance and digital subtraction angiography images were used to validate the radiosurgical outcomes (obliteration or non-obliteration) of lateral sinus DAVF. Cox regression and Kaplan-Meier analyses were performed to determine the correlations between the variables and outcomes. RESULTS: Among the 83 cases, 60 (72%) lateral sinus DAVFs achieved obliteration after a GKRS at a median latency period of 24.5 months. After adjustment for aggressive presentation, cortical venous reflux, straight sinus reflux, and optic nerve sheath enlargement, a CCS of >6 was independently associated with lateral sinus DAVF obliteration (hazard ratio: 2.335, P = 0.007). The estimated 36-month probabilities of obliteration were 80% versus 53.6% for lateral sinus DAVFs with a CCS of >6 versus ≤6. CONCLUSIONS: Lateral sinus DAVFs with a CCS of >6, indicating a nearly patent sinovenous outflow, were more likely to be obliterated after GKRS. Sinovenous outflow patency is a factor associated with therapeutic outcomes in radiosurgery for lateral sinus DAVFs.

Gamma knife radiosurgery for glomus jugulare and tympanicum.

OBJECTIVE: To establish the role of gamma knife radiosurgery (GKS) as a treatment strategy for glomus jugulare and tympanicum. METHOD: A retrospective review of 14 glomus tumors, including 11 glomus jugulare and 3 glomus tympanicum tumors, which were treated by GKS in Taipei Veterans General Hospital from 1993 to 2009, was conducted. Two of these cases had undergone prior surgery with partial tumor resection, and the other 12 cases received primary treatment with GKS after a thorough neuroimaging and cerebral angiography. The tumor volume ranged from 6.5 to 22.1 ml. The maximum dose at the tumor center ranged from 21.6 to 26.3 Gy. All 14 patients were regularly followed up by clinical and radiological evaluations. The median follow-up time was 40.3 months. RESULTS: All 14 patients had significant tumor regression after radiosurgery. The median tumor volume reduction was 34.0% (range 3-79%). Only 1 patient had temporary tumor volume progression (24% increment 6 months post-treatment), accompanied with unilateral facial palsy (from grade III to grade IV) and hearing impairment (from grade I to grade II). The tumor volume of this patient had regressed by 12 months, but facial palsy persisted. The tumor control rate in the series was 100% (n = 14/14), and the preservation rate of cranial nerve function was 92.8% (13/14). There was no complication of lower cranial nerve damage after radiosurgery. CONCLUSION: GKS appeared to be a good alternative or adjuvant to microsurgical resection in patients who are not amenable to complete surgical eradication, with an excellent tumor control rate and little morbidity after long-term follow-up.

Gamma knife radiosurgery for central neurocytoma: retrospective analysis of fourteen cases with a median follow-up period of sixty-five months.

OBJECT: Central neurocytoma (CN) is considered to be a benign neuronal tumor with possible atypical behavior. Microsurgery, radiation therapy (RT) and radiosurgery all have been used in treating this rare disease during the past decade. In this study, the authors present the experience with gamma knife radiosurgery (GKRS) on 14 patients with CN during a median follow-up period of 65 months and document the safety and efficacy of GKRS in the treatment of CN. METHODS: Between November 1997 and December 2009, 14 patients pathologically diagnosed with CN were treated with GKRS. Follow-up magnetic resonance imaging (MRI) was performed at 6-month intervals. Tumor volume and adverse radiation effects (ARE) were documented to evaluate tumor response to GKRS. The Karnofsky Performance Scale (KPS) and neurological status were used to assess clinical outcome. The mean radiation dose prescribed to the tumor margin was 12.1 Gy (ranging from 11 to 13 Gy). The mean tumor volume was 19.6 ml (ranging from 3.5 to 48.9 ml). The mean follow-up period was 70 months (ranging from 30 to 140 months), and the median follow-up period was 65 months. RESULTS: Tumor shrinkage was found in all patients at the final MRI follow-up. The mean volume reduction was 69% (ranging from 47 to 87%). No tumor progression, ARE or radiation-related toxicity developed in any of the cases. The KPS scores of all patients were the same or had increased, and the neurological functions were all stable without deterioration at the final follow-up. CONCLUSION: In our observations, GKRS was found to be an effective and safe alternative as adjuvant therapy for pathology-confirmed CN. The tumor volume and functional outcome can be controlled with a favorable result in long-term observation. Compared with RT and microsurgery, GKRS plays an important role in the treatment of CN as a minimally invasive technique with low morbidity. Regular long-term MRI follow-up should be mandatory to document the tumor response and possible recurrence. Multicenter consortia should be considered for further investigation and evaluation of GKRS for such a rare tumor.

Cost-utility analysis of Parkinson's disease.

Many expensive treatments have been developed for Parkinson's disease (PD), and a good cost-utility analysis is required. Quality-adjusted life-years (QALY) allows comparison of the cost-utility of different medical conditions. If a treatment strategy gives a patient an extra but unhealthy year, the QALY he obtained will be less than one. When a therapeutic strategy is more effective, but causes higher costs, it is mandatory to calculate the incremental cost-effectiveness ratio (ICER). In keeping with guidance from the UK National Institute for Health and Clinical Excellence (NICE), a therapy that deliver QALYs of £20,000 or less are likely to be approved. The threshold used by NICE for the maximum it is prepared to pay for a QALY, which lies between £20,000 and £30,000, will be reviewed case by case. Subthalamic deep brain stimulation (STN-DBS) is an effective therapy, which can improve the quality of life in PD patients immediately, but has not been approved by the Bureau of National Health Insurance here. It has been estimated that the ICER/QALY in STN-DBS patients was of 34,389C= , which is within appropriate limits to consider STNDBS as an efficient therapy. We expect that we can have a decision-making mechanism similar to that of NICE that, according to the ICER of each medical condition, medical resource can be redistributed openly and justly.

Stem cell transplantation and/or adenoviral glial cell line-derived neurotrophic factor promote functional recovery in hemiparkinsonian rats.

BACKGROUND: Parkinson's disease (PD) is a neurological disorder characterized by the progressive loss of midbrain dopamine (DA) neurons. Bone marrow mesenchymal stem cells (BMSCs) can differentiate into multiple cell types including neurons and glia. Transplantation of BMSCs is regarded as a potential approach for promoting neural regeneration. Glial cell line-derived neurotrophic factor (GDNF) can induce BMSC differentiation into neuron-like cells. This work evaluated the efficacy of nigral grafts of human BMSCs (hMSCs) and/or adenoviral (Ad) GDNF gene transfer in 6-hydroxydopamine (6-OHDA)-lesioned hemiparkinsonian rats. AIM: To evaluate the efficacy of nigral grafts of hMSCs and/or Ad-GDNF gene transfer in 6-OHDA-lesioned hemiparkinsonian rats. METHODS: We used immortalized hMSCs, which retain their potential for neuronal differentiation. hMSCs, preinduced hMSCs, or Ad-GDNF effectively enhanced neuronal connections in cultured neurons. In vivo, preinduced hMSCs and/or Ad-GDNF were injected into the substantia nigra (SN) after induction of a unilateral 6-OHDA lesion in the nigrostriatal pathway. RESULTS: Hemiparkinsonian rats that received preinduced hMSC graft and/or Ad-GDNF showed significant recovery of apomorphine-induced rotational behavior and the number of nigral DA neurons. However, DA levels in the striatum were not restored by these therapeutic treatments. Grafted hMSCs might reconstitute a niche to support tissue repair rather than contribute to the generation of new neurons in the injured SN. CONCLUSION: The results suggest that preinduced hMSC grafts exert a regenerative effect and may have the potential to improve clinical outcome.

The Irradiated Brain Volume Within 12 Gy Is a Predictor for Radiation-Induced Changes After Stereotactic Radiosurgery in Patients With Unruptured Cerebral Arteriovenous Malformations.

PURPOSE: Our purpose was to determine whether the coverage of brain parenchyma within the 12 Gy radiosurgical volume (V12) correlates with the development of radiation-induced changes (RICs) in patients with unruptured cerebral arteriovenous malformations (AVM) after undergoing stereotactic radiosurgery (SRS). METHODS AND MATERIALS: This study conducted regular follow-up examinations of 165 patients with unruptured AVMs who had previously undergone SRS. The RICs identified in T2-weighted magnetic resonance imaging (MRI) scans at any time point in the first 3 years after SRS were labeled "early RICs." The RICs identified in T2-weighted MRI scans at 5-year follow-up brain images were labeled "late RICs." Fully automated segmentation was used to analyze the MRI scans from these patients, whereupon the volume and proportion of brain parenchyma within the V12 was calculated. Logistic regression analysis was used to characterize the factors affecting the incidence of early and late RICs of any grade after SRS. RESULTS: The median duration of follow-up was 70 months (range, 36-222). Early RICs were identified in 124 of the 165 patients with the highest grades as followed: grade 1 (103 patients), grade 2 (19 patients), and grade 3 (2 patients). Only 103 patients had more than 5 years follow-up, and late RICs were identified in 70 of 103 patients. Seventeen of 70 patients with late RICs were symptomatic. The median volume and proportion of brain parenchyma within the V12 was 22.4 cm3 (range, 0.6-63.9) and 58.7% (range, 18.4-76.8). Univariate analysis revealed that AVM volume and the brain volume within the V12 were correlated with the incidence of both early and late RICs after SRS. Multivariable analysis revealed that only the brain volume within the V12 was significantly associated with the incidence of early and late RICs after SRS. CONCLUSIONS: In patients with unruptured AVM, the volume of brain parenchyma within the V12 was an important factor associated with the incidence of early and late RICs after SRS. Before SRS, meticulous radiosurgical planning to reduce brain parenchyma coverage within the V12 could reduce the risk of complications.

Delayed microsurgery for vestibular schwannoma after gamma knife radiosurgery.

Stereotactic radiosurgery for vestibular schwannomas (VSs) has become popular during the last decade with promising clinical results after long-term follow-up. However, on rare occasions, some cases have needed traditional microsurgery to remove the tumor several months or years after radiosurgery. We present a retrospective analysis of data acquired during a 16-year period in delayed microsurgery of seven patients with VSs who underwent gamma knife surgery (GKS). A total of 444 with VS underwent GKS between March 1993 and December 2008, and 7 (1.57%) underwent delayed microsurgery at a median of 26 months (range from 3 months to 6 years) after GKS. The mean size of the tumor during GKS was 10.4 ml (range 2.3-23.5 ml). These seven patients were younger, and female predominant. The indications of microsurgery included adverse radiation effect with peri-focal edema, tumor enlargement, and cyst enlargement. Although the perifocal edema could lead to more difficulty in surgery than in typically performed operations for schwannoma, subtotal resection was achieved in all patients. There was no surgery-related morbidity or mortality. The histology showed benign tumor in five patients, malignant peripheral nerve sheath tumor in one, and necrotic tissue in one. The need of microsurgery for further treatment of VS after radiosurgery is rare, but can be a challenge to neurosurgeons in terms of surgical indication, timing, and techniques. The authors concluded the incidence of delayed microsurgery was 1.57% in a series of 444 patients over a 16-year period. We concluded some experience from operative indications, timing, approach, and outcome.

Inhibitory concentration of propofol in combination with dexmedetomidine during microelectrode recording for deep brain stimulator insertion surgeries under general anesthesia.

BACKGROUND: Microelectrode recording (MER) for target refinement is widely used in deep brain stimulator insertion for Parkinson disease. Signals may be influenced by anesthetics when patients receive general anesthesia (GA). This study determined the inhibitory concentration (IC) of propofol on MER signals when it was coadministered with dexmedetomidine. METHODS: Patients were anesthetized with dexmedetomidine (0.5 µg·kg loading, followed by infusion at 0.4 µg·kgh) and propofol through target-controlled infusion for GA with tracheal intubation. The surgeon conducted the online scoring of the background signals, spiking frequency, amplitude, and pattern of single-unit activities by using a 0-10 verbal numerical rating scale (NRS; 0, maximal suppression; 10, minimal suppression), and responses were grouped into suppression (NRS ≤ 6) and nonsuppression (NRS > 6). The median inhibitory concentration (IC50) of propofol (as target effect-site concentrations: Ceprop) was determined using modified Dixon's up-and-down method. Probit regression analysis was further used to obtain the dose-response relationship, and IC05 and IC95 were calculated. RESULTS: Twenty-three adult patients participated in this study. Under the concomitant infusion of dexmedetomidine, the predicted IC50 value (95% CI) of Ceprop for neuronal suppression during MER was 1.29 (1.24-1.34) µg·mL as calculated using modified Dixon's up-and-down method. Using probit analysis, the estimated IC05, IC50, and IC95 values (95% CIs) were 1.17 (0.87-1.23), 1.28 (1.21-1.34), and 1.40 (1.33-1.85) µg·mL, respectively. CONCLUSION: Our data provided reference values of propofol for dosage adjustment to avoid interference on MER under GA when anesthetics have to be continuously infused during recording.

Magnetic resonance imaging as a single diagnostic tool for verifying radiosurgery outcomes of cavernous sinus dural arteriovenous fistula.

PURPOSE: MRI and MR angiography (MRA) are noninvasive methods for examining cavernous sinus dural arteriovenous fistulas (CSDAVFs) after radiosurgery. In this study, we investigated the accuracy of unenhanced MRI/3-dimensional time-of-flight (3D TOF) MRA in evaluating CSDAVF obliteration as compared with digital subtraction angiography (DSA). METHODS: From 1995-2012, 48 cases of CSDAVFs received Gamma Knife surgery (GKS) and had undergone both unenhanced MRI/3D TOF MRA and DSA for posttreatment evaluation. Two blinded observers independently interpreted the results of MRI/MRA. The results of MRI/MRA were compared with those of DSA. The sensitivity (the probability of MRI/MRA showing obliteration when DSA showed complete obliteration), specificity, positive predictive value, and negative predictive value for CSDAVF obliteration were reported. RESULTS: The median interval between the final MRI/MRA and the subsequent DSA was 2 months. Follow-up DSA revealed that 38 of 48 (79.2 %) CSDAVFs were completely obliterated. The results of interobserver agreement assessment showed almost perfect agreement between the 2 observers. For unenhanced MRI/3D TOF MRA, the observed sensitivity was 84.2 %, specificity was 100 %, positive predictive value was 100 %, and negative predictive value was 62.5 %. CONCLUSIONS: Unenhanced MRI/3D TOF MRA alone may be adequate to document the complete obliteration of CSDAVFs after GKS. Time-resolved MRA or DSA can be reserved for a suspected residual CSDAVF after a sufficient latency period after GKS.

Treatment Outcomes of Cavernous Sinus Dural Arteriovenous Fistulas: Comparison of Radiosurgery and Endovascular Embolisation.

BACKGROUND AND PURPOSE: Endovascular treatment (EVT) and stereotaxic gamma-knife radiosurgery (GKRS) can both effectively treat cavernous sinus dural arteriovenous fistulas (CSDAVF). This study compared the prognostic factors and treatment effectiveness of GKRS and EVT for different CSDAVF types. METHODS: The charts of 200 patients undergoing GKRS and 105 patients undergoing EVT were reviewed for data on symptoms (e.g. orbital, cavernous, ocular, and cerebral). The CSDAVFs were classified into proliferative, restrictive, and late restrictive types. The prognostic factors for complete obliteration (CO) were evaluated in both the GKRS and EVT groups and the latent period to CO was measured. For statistical analysis χ2-tests were used to compare final CO rates for EVT and GKRS across the three CSDAVF types. RESULTS: The EVT and cavernous symptoms were significant independent predictors of CO. The CO rate after EVT (97.9%) was significantly higher than that after GKRS (63.5%) for restrictive CSDAVFs (P < 0.001) but not for proliferative or late restrictive types. In the GKRS group, cavernous symptoms (hazard ratio, HR: 0.557) and target volume (HR: 0.853) predicted CO, but only target volume remained significant in multivariate analysis. In the EVT group, the latent period to CO was shortest for restrictive CSDAVFs (3.2 ± 1.6 months, P = 0.05). CONCLUSION: Angioarchitecture did not affect treatment outcomes. Cavernous symptoms were strongly associated with lower complete obliteration rates in the GKRS but not the EVT group. The EVT method remains the treatment of choice, especially for restrictive CSDAVFs; however, compared to EVT, GKRS had lower complication rates and similar therapeutic effects for proliferative type fistulas.

Trigeminal Nerve Atrophy Predicts Pain Recurrence After Gamma Knife Stereotactic Radiosurgery for Classical Trigeminal Neuralgia.

BACKGROUND: Trigeminal nerve atrophy and neurovascular compression (NVC) are frequently observed in classical trigeminal neuralgia (CTN). OBJECTIVE: To determine whether nerve characteristics contribute to Gamma Knife (Elekta AB, Stockholm, Sweden) surgery (GKS) outcomes in unilateral CTN without previous surgery. METHODS: From 2006 to 2012, 67 patients with unilateral CTN without previous surgery received GKS with a maximal dose of 90 Gy delivered to the trigeminal nerve juxta brainstem. Two evaluators, blinded to the side of pain, analyzed the magnetic resonance images before GKS to obtain the parameters, including nerve cross-sectional area (CSA), vessel type of NVC, and site of NVC along the nerve. Correlations of the parameters with pain relief (Barrow Neurological Institute [BNI] grades I-IIIb) and recurrence (BNI grades VI-V) were made by using Cox regression and Kaplan-Meier analyses. RESULTS: The median CSA of the symptomatic nerves was significantly smaller than that of the asymptomatic nerves (4.95 vs 5.9 mm2, P < .001). After adjustment for age and sex, larger nerve CSA was associated with lower initial pain relief (hazard ratio 0.81, P = .03) and lower pain recurrence after initial response (hazard ratio 0.58, P = .02). Patients with nerve atrophy (CSA of ≤ 4.4 mm2 after receiver operating characteristic curve analysis) had a lower 5-yr probability of maintaining pain relief after initial response than those without nerve atrophy (65% vs 86%, P = .04). CONCLUSION: Trigeminal nerve atrophy may predict pain recurrence in patients with initial post-GKS relief of CTN. Arterial and proximal NVC are not predictive of GKS outcomes. Future studies are required to determine optimal treatments for long-term pain relief in patients with CTN and trigeminal nerve atrophy.

Fully automated tissue segmentation of the prescription isodose region delineated through the Gamma knife plan for cerebral arteriovenous malformation (AVM) using fuzzy C-means (FCM) clustering.

BACKGROUND: Gamma knife radiosurgery (GKRS) is a common treatment for cerebral arterio-venous malformations (AVMs), particularly in cases where the malformation is deep-seated, large, or in eloquent areas of the brain. Unfortunately, these procedures can result in radiation injury to brain parenchyma. The fact that every AVM is unique in its vascular morphology makes it nearly impossible to exclude brain parenchyma from isodose radiation exposure during the formulation of a GKRS plan. Calculating the percentages of the various forms of tissue exposed to specific doses of radiation is crucial to understanding the clinical responses and causes of brain parenchyma injury following GKRS for AVM. METHODS: In this study, we developed a fully automated algorithm using unsupervised classification via fuzzy c-means clustering for the analysis of T2 weighted images used in a Gamma knife plan. This algorithm is able to calculate the percentages of nidus, brain tissue, and cerebrospinal fluid (CSF) within the prescription isodose radiation exposure region. RESULTS: The proposed algorithm was used to assess the treatment plan of 25 patients with AVM who had undergone GKRS. The Dice similarity index (SI) was used to determine the degree of agreement between the results obtained using the algorithm and a visually guided manual method (the gold standard) performed by an experienced neurosurgeon. In the nidus, the SI was (74.86 ±â€¯1.30%) (mean ±â€¯standard deviation), the sensitivity was (83.05 ±â€¯11.91)%, and the specificity was (86.73 ±â€¯10.31)%. In brain tissue, the SI was (79.50 ±â€¯6.01)%, the sensitivity was (73.05 ±â€¯9.77)%, and the specificity was (85.53 ±â€¯7.13)%. In the CSF, the SI was (69.57 ±â€¯15.26)%, the sensitivity was (89.86 ±â€¯5.87)%, and the specificity was (92.36 ±â€¯4.35)%. CONCLUSIONS: The proposed clustering algorithm provides precise percentages of the various types of tissue within the prescription isodose region in the T2 weighted images used in the GKRS plan for AVM. Our results shed light on the causes of brain radiation injury after GKRS for AVM. In the future, this system could be used to improve outcomes and avoid complications associated with GKRS treatment.

Venous outflow restriction as a predictor of cavernous sinus dural arteriovenous fistula obliteration after Gamma Knife surgery.

OBJECTIVE: Gamma Knife surgery (GKS) obliterates 65%-87% of cavernous sinus dural arteriovenous fistulas (CSDAVFs). However, the hemodynamic effect on GKS outcomes is relatively unknown. The authors thus used the classification scheme developed by Suh et al. to explore this effect. METHODS: The authors retrospectively (1993-2016) included 123 patients with CSDAVFs who received GKS alone at the institute and classified them as proliferative type (PT; n = 23), restrictive type (RT; n = 61), or late restrictive type (LRT; n = 39) after analyzing their pre-GKS angiography images. Treatment parameters, the presence of numerous arterial feeders, and venous drainage numbers were compared across the CSDAVF types. Patients' follow-up MR images were evaluated for the presence of complete obliteration. A Kaplan-Meier analysis was conducted to determine the correlation between CSDAVF types and outcomes. RESULTS: The 36-month probability of complete obliteration was 74.3% for all patients, with no significant differences across types (p = 0.56). PT had the largest radiation volume (6.5 cm3, p < 0.001), the most isocenters (5, p = 0.015) and venous drainage routes (3, p < 0.001), and the lowest peripheral dose (16.6 Gy, p = 0.011) and isodose level coverage (64.3%, p = 0.006). CSDAVFs presenting with ocular patterns were less likely to be completely obliterated (hazard ratio 0.531, p = 0.009). After adjustment for age, CSDAVFs with more venous drainage routes were less likely to be completely obliterated (hazard ratio 0.784, p = 0.039). CONCLUSIONS: GKS is an equally effective treatment option for all 3 CSDAVF types. Furthermore, the number of venous drainage routes may help in predicting treatment outcomes and making therapeutic decisions.