RESUMEN
Spontaneous gas-bubble nucleation in weak gas-liquid solutions has been a challenging topic in theory, experimentation, and computer simulations. In analogy with recent advances in crystallization and droplet formation studies, the diffusive-shielding stabilization and thermodynamic irreversibility of bulk nanobubble (bNB) mechanisms are revisited and deployed to characterize nucleation processes in a stochastic framework of computer experiments using the large-scale atomic/molecular massively parallel simulator code. Theoretical bases, assumptions, and limitations underlying the irreversibility hypothesis of bNBs, and their computational counterparts, are extensively described and illustrated. In essence, it is established that the irreversibility hypothesis can be numerically investigated by converging the system volume (due to the finiteness of interatomic forces) and the initial dissolved-gas concentration in the solution (due to the single-bNB limitation). Helium nucleation in liquid Pb17Li alloy is selected as a representative case study, where it exhibits typical characteristics of noble-gas/liquid-metal systems. The proposed framework lays down the bases on which the stability of gas-bNBs in weak and supersaturated gas-liquid solutions can be inferred and explained from a novel perspective. In essence, it stochastically marches toward a unique irreversible state along out-of-equilibrium nucleation/growth trajectories. Moreover, it does not attempt to characterize the interface or any interface-related properties, neither theoretically nor computationally. It was concluded that bNBs of a few tens of He-atoms are irreversible when dissolved-He concentrations in the weak gas-liquid solution are at least â¼50 and â¼105 mol m-3 at 600 and 1000 K (and â¼80 MPa), respectively, whereas classical molecular dynamics -estimated solubilities are at least two orders of magnitude smaller.
RESUMEN
CSF leak-related pneumocephalus is a rare complication of endoscopic transsphenoidal surgery (ETSS) and has been reported in previous studies. We are presenting a rare case of subdural pneumocephalus, unassociated with CSF leak, that developed in the sellar and suprasellar regions. This complication was diagnosed in an adult male 1 week after the removal of a large tumor in the same site via ETSS. The patient presented with a severe headache and visual deterioration. He was diagnosed by a CT scan and managed emergently via ETSS. The headache was relieved immediately after surgery, and the recent visual deterioration was reversed the next day. As far as we have reviewed in the context of complications of ETSS, no previous study has reported such a complication of pneumocephalus unassociated with CSF leak following ETSS. As a conclusion, pneumocephalus can occur with or without CSF leakage as a complication of ETSS, and it may be avoided by a good (water-tight) sealing of the surgical site.
RESUMEN
Epidermoid cysts (EC) are benign lesions resulting from incomplete separation of the neuroectoderm during embryonic development. The investigation of choice for EC is magnetic resonance imaging (MRI). Surgical resection is the treatment of choice. Full resection of EC including the cyst wall to prevent recurrence and malignant transformation should be considered when possible. Two main approaches were described in the literature and included craniotomy and endoscopic endonasal approach (EEA). Using of EEA to accomplish total resection could be challengeable. To best of our knowledge, only 6 manuscripts (with a total of eight patients) reported total resection of EC by using EEA. Our case should be the ninth such cases in the literature. In this paper, we reported a case of sellar and suprasellar epidermoid cyst which was resected completely by using EEA. We revealed the safety and efficacy of this approach in management of such cases.
RESUMEN
Cochlear implantation surgery in the rare cases of incomplete partition type III is constrained by intraoperative difficulties that result from the deformed cochlea. Our case study describes the use of a supporting fascia pad that served as a track to preserve the direction of the electrode during insertion into the cochlear lumen.
RESUMEN
Hydatidosis is a chronic zoonotic infection of humans caused by the infestation of larvae of the tapeworm Echinococcus granulosus. All parts of the body can be infected, especially the liver and lungs. Intraorbital hydatid cyst (HC) is a rare entity and accounts for less than 1% of all hydatid cysts. Total resection of the cyst can be very challenging due to the limited area within the orbit and the severe adhesion to adjacent structures. Several surgical approaches have been described in the literature depending on the size and location of the cyst. We reported a case of retrobulbar HC in a 10-year-old boy which was completely resected using the Lynch approach. Our case should be the second reported case from Syria and the first case that used the Lynch approach in the literature.
RESUMEN
BACKGROUND: We aim to report a rare case of a herniated mastoid segment of the facial nerve that was accidently discovered during cochlear implantation surgery and how altering the surgery plan could achieve the implantation while preserving the nerve. CASE PRESENTATION: A four-year-old girl presented with profound bilateral sensorineural hearing loss that did not completely resolve after 2 years of using hearing aids was scheduled for cochlear implantation surgery in the right ear. During surgery, a herniated mastoid segment of the facial nerve took an anterior course and obstructed the access to the round window. CONCLUSION: When a traditional posterior tympanotomy approach in cochlear implantation surgery is limited in cases of a herniated facial nerve, a tunnel created near the inferior part of the posterior wall of the auditory canal provided safe insertion of the electrode. It also permitted placement of a piece of fascia between the electrode and the facial nerve, therefore, protecting the facial nerve from electrical stimuli.