ABSTRACT
BACKGROUND: Arachnoid cysts (ACs) are congenital abnormalities that can be located anywhere within the subarachnoid space along the cerebrospinal axis, although they are most often found on the left side in the temporal fossa and sylvian fissure. ACs comprise approximately 1% of all intracranial space-occupying lesions and are considered potential risk factors for subdural hematoma (SDH) in individuals of all age groups who have experienced traumatic brain injury. Although it is uncommon for an intracystic hemorrhage of an AC to occur without evidence of head trauma, it may be more common among children and young adults. Here, the authors present three cases of spontaneous AC intracystic hemorrhage with chronic SDH. Additionally, they provide a thorough review of the existing literature. OBSERVATIONS: All three patients with AC were adolescent males. In all cases, AC was identified using the Galassi classification (type II or III) and associated with spontaneous intracystic hemorrhage and chronic SDH as seen on imaging. LESSONS: Spontaneous intracystic hemorrhage is a rare complication and occurs most commonly on the left side. Surgery is the definitive treatment, requiring either craniotomy or burr hole for hematoma evacuation and microsurgical fenestration to drain the cyst into the subarachnoid cisterns.
ABSTRACT
A typical structure of thermal spray coatings consisted of molten particles, semi-molten particles, oxides, pores, and cracks. These factors caused the porosity of sprayed coatings, leading to a significant influence on the coating properties, especially their wear-corrosion resistance. In this study, a post-spray sealing treatment of Cr3C2-NiCr/Al2O3-TiO2 plasma-sprayed coatings was carried out, and then, their corrosion properties were evaluated, before and after the treatment. For the sealing process, aluminum phosphate (APP) containing Al2O3 nanoparticles (~10 nm) was used. The permeability of APP into the sprayed coating was analyzed by SEM-EDS. The treatment efficiency for porosity and corrosion resistance of sprayed coatings was evaluated by electrochemical measurements, such as the potentiodynamic polarization and electrochemical impedance spectroscopy. The wear-corrosion resistance of the coating was examined in 3.5 wt.% NaCl circulation solution containing 0.25% SiO2 particles. The sealing efficiency was evaluated by the percentage of the treated open pores in the coating. The obtained results showed that APP penetrated deeply through the coating and the incorporation of Al2O3 nanoparticles into APP sealant improved the sealing efficiency by 20% of open pores in comparison with the sealant without nano-Al2O3. The effect of the post-treatment on corrosion protection of the sprayed coating has been discussed.
