Spinal anesthesia is widely used for many obstetric, gynecological, orthopedic, and urological operations. Subdural hematomas may occur after trauma and are associated with high morbidity and mortality rates. Postdural puncture headache (PDPH) is a benign condition and the most frequent complication of spinal anesthesia. The high rate of headache after spinal anesthesia may mask or delay the diagnosis of subdural hematoma. The true incidence of postdural puncture subdural hematoma (PDPSH) is unknown because most affected patients are probably managed without investigation. Therefore, the true incidence of PDPSH may be greater than suggested by previous reports. The differentiation of headache associated with subdural hematoma from PDPH is crucial. We herein report two cases of bilateral subdural hematoma after epidural anesthesia and emphasize the importance of suspicion for PDPSH and careful evaluation of patients with headache after spinal anesthesia.
Anesthesia, Epidural ; Anesthesia, Spinal ; Diagnosis ; Headache ; Hematoma, Subdural* ; Humans ; Incidence ; Masks ; Mortality ; Orthopedics ; Post-Dural Puncture Headache* ; Punctures*

PURPOSE: The aim of the study was to evaluate the effect of annealing on the nanostructure and hardness of Co-Cr metal ceramic samples that were fabricated with a direct metal laser sintering (DMLS) technique. MATERIALS AND METHODS: Five groups of Co-Cr dental alloy samples were manufactured in a rectangular form measuring 4 x 2 x 2 mm. Samples fabricated by a conventional casting technique (Group I) and prefabricated milling blanks (Group II) were examined as conventional technique groups. The DMLS samples were randomly divided into three groups as not annealed (Group III), annealed in argon atmosphere (Group IV), or annealed in oxygen atmosphere (Group V). The nanostructure was examined with the small-angle X-ray scattering method. The Rockwell hardness test was used to measure the hardness changes in each group, and the means and standard deviations were statistically analyzed by one-way ANOVA for comparison of continuous variables and Tukey's HSD test was used for post hoc analysis. P values of <.05 were accepted as statistically significant. RESULTS: The general nanostructures of the samples were composed of small spherical entities stacked atop one another in dendritic form. All groups also displayed different hardness values depending on the manufacturing technique. The annealing procedure and environment directly affected both the nanostructure and hardness of the Co-Cr alloy. Group III exhibited a non-homogeneous structure and increased hardness (48.16 +/- 3.02 HRC) because the annealing process was incomplete and the inner stress was not relieved. Annealing in argon atmosphere of Group IV not only relieved the inner stresses but also decreased the hardness (27.40 +/- 3.98 HRC). The results of fitting function presented that Group IV was the most homogeneous product as the minimum bilayer thickness was measured (7.11 A). CONCLUSION: After the manufacturing with DMLS technique, annealing in argon atmosphere is an essential process for Co-Cr metal ceramic substructures. The dentists should be familiar with the materials that are used in clinic for prosthodontics treatments.
Alloys ; Argon ; Atmosphere ; Ceramics ; Dental Alloys* ; Dentists ; Electron Probe Microanalysis ; Hardness Tests ; Hardness* ; Humans ; Metal Ceramic Alloys ; Nanostructures* ; Oxygen ; Prosthodontics