RESUMEN
A new orthophosphate α-Na2Ni2Fe(PO4)3 was synthesized using a solid state reaction route, and its crystal structure was determined from powder X-ray diffraction data. The physical properties of α-Na2Ni2Fe(PO4)3 were studied by magnetic and electrochemical measurements and by Mössbauer and Raman spectroscopy. α-Na2Ni2Fe(PO4)3 crystallizes according to a stuffed α-CrPO4-type structure with the space group Imma and the cell parameters a = 10.42821(12), b = 13.19862(15), c = 6.47634(8) Å, and Z = 4. The structure consists of a 3D-framework of octahedra and tetrahedra sharing corners and/or edges with channels along [100] and [010], in which the sodium atoms are located. The (57)Fe Mössbauer spectrum indicates that the Fe(3+) cation is distributed over two crystallographic sites implying the presence of a Ni(2+)/Fe(3+) statistical disorder. Magnetic susceptibility follows the Curie-Weiss behavior above 100 K with θ = -114.3 K indicating the occurrence of predominant antiferromagnetic interactions. Electrochemical tests indicate that during the first discharge to 1 V vs. Na(+)/Na in a sodium cell, one Na(+) ion could be inserted into the α-Na2Ni2Fe(PO4)3 structure. This has led to the formation of a new phase Na3Ni2Fe(PO4)3 which was found to be promising as a positive electrode material for sodium batteries. When α-Na2Ni2Fe(PO4)3 is further discharged to 0.03 V, it delivers a capacity of 960 mA h g(-1). This corresponds to the intercalation of more than seven sodium atoms per formula unit which is an indication of a conversion-type behaviour with the formation of metallic Fe and Ni. When cycled in the voltage range 0.03-3 V vs. Na(+)/Na, at 20 °C, under the current rates of 50, 100, 200, and 400 mA g(-1), reversible capacities of 238, 196, 153, and 115 mA h g(-1), were obtained, respectively.
RESUMEN
OBJECTIVE: To report a case of meningioma arising from the nervus intermedius. METHODS: This paper comprises a case report, literature review, and discussion regarding the presentation of a nervus intermedius meningioma, comparing and contrasting this to other relevant neoplasms of the internal auditory canal and cerebellopontine angle. RESULTS: Tumours of the cerebellopontine angle include vestibular schwannomas, facial schwannomas and, more rarely, nervus intermedius schwannomas. The nervus intermedius is a division of the facial nerve at the cerebellopontine angle, with parasympathetic and afferent somatic components. Our patient presented with progressive hearing loss. An ipsilateral internal auditory canal mass at the fundus, as indicated by magnetic resonance imaging and electroneuronography, was suggestive of vestibular schwannoma. Intra-operative dissection revealed a nervus intermedius tumour. Histological evaluation indicated a meningioma rather than a schwannoma. CONCLUSION: This is the first reported case of meningioma involving the nervus intermedius. The implications this pathology may have on surgical approach, facial nerve outcomes, and the need for improved pre-operative imaging and intra-operative monitoring are discussed. A review of the current literature on nervus intermedius tumour is provided.
Asunto(s)
Neoplasias Meníngeas/diagnóstico , Meningioma/diagnóstico , Neoplasias Cerebelosas/diagnóstico , Ángulo Pontocerebeloso , Neoplasias de los Nervios Craneales/diagnóstico , Diagnóstico Diferencial , Enfermedades del Nervio Facial/diagnóstico , Pérdida Auditiva Sensorineural/etiología , Humanos , Masculino , Persona de Mediana Edad , Neuroma Acústico/diagnósticoRESUMEN
Trans-sphenoidal surgery was first described more than a century ago. Today, this approach occupies a crucial place in the armamentarium of the neurosurgeon for the management of sellar, suprasellar, and parasellar pathological conditions. Over the years, the procedure has witnessed multiple modifications, benefitting from technological advances and from innovative ideas of pioneering neurosurgeons and otolaryngologists. The introduction of the microscope and then the endoscope allowed progressive improvement of visualization, illumination, and magnification in this restricted surgical corridor. With enhanced knowledge and understanding of the surgical anatomy of the skull base, the application of extended transsphenoidal approaches became possible, thus widening significantly the anatomical area that can be reached through this approach. In addition, the continuous improvement in imaging, image guidance, and microinstruments allowed better planning and precision during surgery. In sum, thanks to recent technological advance, trans-sphenoidal surgery can now be applied to a large area of the skull base and for a wide range of pathological conditions. With growing experience, the procedure is performed with enhanced safety and greater efficacy. In this paper, we review the historical evolution of trans-sphenoidal surgery and describe the modern applications and modifications of the procedure.
Asunto(s)
Encefalopatías/cirugía , Procedimientos Neuroquirúrgicos/métodos , Hueso Esfenoides/cirugía , Adulto , Neoplasias Encefálicas/cirugía , Cordoma/cirugía , Humanos , Masculino , Neoplasias Meníngeas/cirugía , Meningioma/cirugía , Procedimientos Neuroquirúrgicos/instrumentación , Base del Cráneo/cirugía , Neoplasias de la Base del Cráneo/cirugíaRESUMEN
BACKGROUND: The optimal treatment of low grade intramedullary spinal cord tumours remains controversial. In many cases the tumours continue to progress even after surgery and radiation. Effective chemotherapy may be an important therapeutic adjunct in this setting. Temozolomide is widely used for brain gliomas, yet its role in the management of spinal cord tumours has not been reported. PROCEDURE: Two paediatric patients with low grade spinal cord astrocytomas were diagnosed to have progression of the tumour in spite of surgery and radiotherapy. They received temozolomide, 200 mg/m2 daily for five days every four weeks for 10 cycles, and were followed serially. RESULTS: Stabilization of the spinal tumour in both patients was observed at 18 months of follow-up. One of the patients developed haematological toxicity requiring platelet transfusion and dose reduction. CONCLUSION: Based on our findings in two paediatric patients, temozolomide may be a useful agent in the management of progressive recurrent low grade spinal cord astrocytomas.
Asunto(s)
Antineoplásicos Alquilantes/administración & dosificación , Astrocitoma/terapia , Dacarbazina/análogos & derivados , Neoplasias de la Médula Espinal/terapia , Médula Espinal/patología , Adolescente , Astrocitoma/diagnóstico , Astrocitoma/fisiopatología , Niño , Dacarbazina/administración & dosificación , Progresión de la Enfermedad , Esquema de Medicación , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Neoplasias Meníngeas/secundario , Metástasis de la Neoplasia/diagnóstico , Metástasis de la Neoplasia/tratamiento farmacológico , Metástasis de la Neoplasia/fisiopatología , Recurrencia Local de Neoplasia/tratamiento farmacológico , Recurrencia Local de Neoplasia/fisiopatología , Recurrencia Local de Neoplasia/prevención & control , Procedimientos Neuroquirúrgicos , Radioterapia , Médula Espinal/efectos de los fármacos , Médula Espinal/fisiopatología , Neoplasias de la Médula Espinal/diagnóstico , Neoplasias de la Médula Espinal/fisiopatología , Temozolomida , Resultado del TratamientoRESUMEN
Spontaneous subdural haematoma is very rare in young patients. The complications of anabolic steroid intake in weight lifters are numerous, yet subdural haematomas have not been reported. We report on two cases of spontaneous subdural haematomas in young weight lifters. Both patients underwent surgical evacuation and made a full recovery. A review of the literature on the complications associated with valsalva manoeuvres is also presented including hemodynamic and intracranial changes. We propose that patients on chronic anabolic steroids may have vascular changes that predispose them to bleeding during a Valsalva manoeuvre (VM).