Immediate angiographic control after intra-arterial nimodipine administration underestimates the vasodilatory effect.

Intra-arterial nimodipine administration is a widely used rescue therapy for cerebral vasospasm. Although it is known that its effect sets in with delay, there is little evidence in current literature. Our aim was to prove that the maximal vasodilatory effect is underestimated in direct angiographic controls. We reviewed all cases of intra-arterial nimodipine treatment for subarachnoid hemorrhage-related cerebral vasospasm between January 2021 and December 2022. Inclusion criteria were availability of digital subtraction angiography runs before and after nimodipine administration and a delayed run for the most affected vessel at the end of the procedure to decide on further escalation of therapy. We evaluated nimodipine dose, timing of administration and vessel diameters. Delayed runs were performed in 32 cases (19 patients) with a mean delay of 37.6 (± 16.6) min after nimodipine administration and a mean total nimodipine dose of 4.7 (± 1.2) mg. Vessel dilation was more pronounced in delayed vs. immediate controls, with greater changes in spastic vessel segments (n = 31: 113.5 (± 78.5%) vs. 32.2% (± 27.9%), p < 0.0001) vs. non-spastic vessel segments (n = 32: 23.1% (± 13.5%) vs. 13.3% (± 10.7%), p < 0.0001). In conclusion intra-arterially administered nimodipine seems to exert a delayed vasodilatory effect, which should be considered before escalation of therapy.

Impact of aneurysm shape and neck configuration on cerebral infarction during microsurgical clipping of intracranial aneurysms.

OBJECTIVE: Cerebral infarction is a significant cause of morbidity and mortality related to microsurgical clipping of intracranial aneurysms. The objective of this study was to determine the impact of aneurysm shape and neck configuration on cerebral infarction after aneurysm surgery. METHODS: The authors retrospectively reviewed consecutive cases of ruptured and unruptured aneurysms treated with microsurgical clipping at their institution between 2010 and 2018. Three-dimensional reconstructions from preoperative computed tomography and digital subtraction angiography were used to determine aneurysm shape (regular/complex) and neck configuration (regular/irregular). Morphological and procedure-related risk factors for cerebral infarction were identified using univariate and multivariate statistical analyses. RESULTS: Among 243 patients with 252 aneurysms (148 ruptured, 104 unruptured), the overall cerebral infarction rate was 17.1%. Infarction tended to occur more often in aneurysms with complex shape (p = 0.084). Likewise, aneurysms with an irregular neck had a significantly higher rate of infarction (37.5%) than aneurysms with regular neck configuration (10.1%, p < 0.001). Aneurysms with an irregular neck were associated with a higher rate of intraoperative rupture (p = 0.003) and temporary parent artery occlusion (p = 0.037). In the multivariate analysis, irregular neck configuration was identified as an independent risk factor for infarction (OR 4.2, 95% CI 1.9-9.4, p < 0.001), whereas the association between aneurysm shape and infarction was not significant (p = 0.966). CONCLUSIONS: Irregular aneurysm neck configuration represents an independent risk factor for cerebral infarction during microsurgical clipping of both ruptured and unruptured aneurysms.

Application of Intraoperative FLOW 800 Indocyanine Green Videoangiography Color-Coded Maps for Microsurgical Clipping of Intracranial Aneurysms.

OBJECTIVE: Indocyanine green (ICG) videoangiography (VAG) is an established method for assessment of cerebral blood flow during microsurgical clipping of intracranial aneurysms. FLOW 800 is a surgical microscope-integrated software program that shows the cerebral blood flow in color-coded maps, thus providing semi-quantitative and real-time analysis of ICG data. We aimed to establish reference values for FLOW 800 parameters before and after microsurgical clipping of intracranial aneurysms and to evaluate the potential of FLOW 800 to guide intraoperative decisions. METHODS: We retrospectively reviewed 54 patients (mean age, 53.6 ± 11.6 years) who underwent microsurgical clipping for 60 aneurysms and intraoperative evaluation of ICG fluorescence dynamics using FLOW 800 color-coded maps. FLOW 800 data were correlated with patient characteristics, clinical outcomes, and intraoperative decision making. RESULTS: There were no significant differences in FLOW 800 data between ruptured and unruptured aneurysms (P > 0.05). Likewise, the hemodynamic parameters were not significantly different before and after definite clip placement (P > 0.05). However, in 2 cases, analysis of transit times by FLOW 800 analysis showed a hemodynamically significant clip stenosis that might have been missed by conventional ICG-VAG and resulted in adjustment of the clip position. Overall, there was 1 cerebral infarction, which was not related to clip placement. CONCLUSIONS: FLOW 800 is a useful adjunct to ICG-VAG for intraoperative assessment of cerebral perfusion and may help to identify hemodynamically relevant clip stenosis. The beneficial impact of FLOW 800 on clinical outcome after microsurgical clipping needs to be confirmed by comparative studies.

Elective Treatment of Additional and Recurrent Aneurysms in Patients with a Previous Subarachnoid Hemorrhage: A Single-Center Analysis of Complications and Clinical Outcome.

OBJECTIVE: Subarachnoid hemorrhage (SAH) can be associated with a degree of resulting brain damage and subsequent reorganization of the central nervous system. The aim of this study was to evaluate complication rates and clinical outcome in patients with a previous SAH who were treated for a recurrent or an additional, initially unruptured aneurysm. METHODS: A retrospective single-center study was conducted for patients who underwent elective treatment by surgical or endovascular means between 2010 and 2018. We compared patients with a previous SAH and without history of SAH in terms of complication rates and functional outcomes (modified Rankin Scale [mRS]). RESULTS: The study population consisted of 337 patients (non-SAH, 270; SAH, 67) who underwent 390 elective procedures for treatment of 443 aneurysms. Procedure-related complications occurred in 13.5% of patients with a previous SAH and in 13.3% of patients without SAH (P = 1.0). At the 6-month follow-up, the morbidity (defined as any increase on the mRS) was comparable between the SAH group (6.7%) and the non-SAH group (7.6%; P = 0.5). Overall favorable outcome (mRS score ≤2) was achieved by 96.6% in the SAH group and 97.3% in the non-SAH group (P = 1.0). Also, in patients with a previous SAH, the choice of clipping or endovascular treatment did not have a significant impact on clinical outcome at the 6-month follow-up. CONCLUSIONS: Treatment of recurrent or additional aneurysms in patients with a previous SAH can be performed with acceptable complication rates and morbidity by either surgical or endovascular means.

The hygroscopic behaviour of individual aerosol particles in nickel refineries as investigated by environmental scanning electron microscopy.

The hygroscopic properties of individual aerosol particles (1-35 microm equivalent projected area diameter) from the Roasting, Anode Casting and Electrorefining Departments of two Ni refineries were studied by environmental scanning electron microscopy (ESEM) and energy-dispersive X-ray microanalysis (EDX) at a relative humidity of 96-98% (at a temperature of 5 degrees C). In the Roasting and Anode Casting Departments, most particles (60-85% by number) showed no visible change in size or surface morphology when exposed to high relative humidity. Approximately 15-30% of the particles developed a thin water film (growth factors between 1.006 and 1.06) indicating the presence of thin surface coatings of sulfates. About 10% of the particles in the Roasting Department formed droplets (growth factors between 1.1 and 2.6) which always contained a large portion of insoluble material. In the Electrorefining Department, most particles (approximately 60%) were residues from the electrolysis bath solution. At a relative humidity of 96-98% these particles formed a solution which contained only small insoluble inclusions. About 30% of the particles in the Electrorefining Department developed thin water films. As only a small fraction of the particles increased substantially in size when exposed to high relative humidity, the deposition pattern of the total aerosol mass fraction will not be changed substantially by hygroscopic growth. The frequent occurrence of thin surface coatings of soluble material on insoluble Ni compounds has to be considered for health assessment purposes.