Anatomía radiológica de la base de cráneo y los nervios craneales parte 2: Nervios craneales / Skull base and cranial nerves radiologic anatomy part 2: Cranial nerves

Resumen: La anatomía de la base del cráneo es compleja. Numerosas estructuras neurovasculares vitales pasan a través de múltiples canales y agujeros ubicados en la base del cráneo. Con el avance de la tomografía computarizada (TC) y la resonancia magnética (RM), es posible la localización cada vez más precisa de lesiones y la evaluación de su relación con las estructuras neurovasculares adyacentes. El trayecto de los nervios craneales sigue un recorrido conocido y se transmiten a la cara y cuello por los forámenes de base de cráneo. La tomografía computada y la resonancia magnética son complementarias entre sí y, a menudo, se usan juntas para demostrar la extensión total de la enfermedad. La segunda parte de esta revisión se centra en el estudio radiológico de los nervios craneales.

Abstract: The skull base anatomy is complex. Many vital neurovascular structures course through the skull base canals and foramina. With the advancement of CT and MRI, the localization of lesions has become more precise as their relationship with adjacent neurovascular structures. There is a known course of the cranial nerves as well as their skull base exiting foramina to the head and neck. CT and MRI are complimentary modalities and are often used together to map the full extent of disease. The second article in this review focus on the radiologic study of the cranial nerves.

Análisis crítico del registro de epicrisis del equipo de cirugía digestiva Hospital Base Valdivia / Critical analysis on epicrisis records of the digestive surgery team at the Hospital Base Valdivia

El registro de las patologías que se presentan en un servicio clínico es fundamental para conocer la realidad de dicha institución y las necesidades que éste debe suplir a la población que cubre. El Equipo de Cirugía Digestiva del HBV mantiene un registro controlado de las patologías que son tratadas ahí, además de las distintas variables que las afectan, en base a las epicrisis confeccionadas al momento del alta de cada paciente. El objetivo de este trabajo es realizar un análisis acabado de la base de datos y evaluar críticamente el método de confección existente, además de conocer las patologías que se tratan diariamente y su epidemiología local. Se revisa el registro de las epicrisis del Equipo de Cirugía Digestiva del HBV, durante el periodo comprendido entre enero y diciembre de 2006, las que se encuentran registradas en una planilla Excel que incluye variables como edad, sexo, procedencia, tipo de intervención y complicaciones para cada diagnóstico realizado, y se analizan entre sí; éstas demuestran que durante dicho año, debieron ser hospitalizados 884 pacientes, la mayoría de sexo femenino y edad avanzada, exceptuando en los adolescentes que, aunque minoría, predomina el sexo masculino. El número mensual de pacientes permanece estable durante todo el año. La patología más frecuente es la hepatobiliar (37,3 por ciento), donde destaca la patología litiásica (53,4 por ciento); en segundo lugar se presentan las neoplasias (23,4 por ciento) destacando el cáncer colorrectal (34,5 por ciento) y gástrico (28 por ciento). El 69,3 por ciento de las patologías requirió algún tipo de intervención quirúrgica, 52,3 por ciento de carácter electivo. Dentro de las pocas complicaciones que se presentaron (11,3 por ciento) destacan infección de herida operatoria, neumonía intrahospitalaria y filtración de anastomosis. A pesar de los alentadores resultados, existe una pérdida no despreciable de epicrisis y por lo tanto un subregistro de la realidad y además una gama...

Apendicectomía en blanco: análisis de 106 casos / Appendicectomy in normal appendix: report of 106 cases

La apendicectomía es la intervención quirúrgica más frecuente en los servicios de urgencia. La clínica, fundamental en el diagnóstico de apendicitis aguda, no siempre es categórica, debido a que los síntomas y signos pueden resultar ambiguos. No obstante, los métodos de laboratorio e imagenológicos no han logrado superarla en cuanto a rendimiento, por lo que sólo cumplen un rol de ayuda en casos específicos. El objetivo del presente estudio es mostrar y analizar los casos de pacientes apendicectomizados con diagnóstico de apendicitis aguda, cuyo informe histopatológico de la pieza operatoria resultó negativo para dicha patología. Se estudian retrospectivamente 677 casos mediante revisión de los informes de biopsias correspondientes al total de los pacientes operados en el Hospital Clínico Regional Valdivia entre enero y diciembre de 2004. Se revisan las fichas clínicas de los casos con diagnóstico histopatológico negativo, analizando luego mediante una planilla Excel variables como edad, sexo, procedencia, clínica, parámetros de laboratorio, período de evolución, tiempo de hospitalización, hallazgos intraoperatorios, diagnóstico histopatológico y morbimortalidad quirúrgica. Se realizaron 106 apendicectomías en blanco (15,7 por ciento), correspondiendo 54 por ciento a mujeres. La edad promedio fue de 23,5 años (1-77). Una paciente presentaba un embarazo de 23 semanas (0,94 por ciento). El tiempo de evolución preoperatorio presentó un promedio y mediana de 1,96 días (1-11). En el 38,7 por ciento de los casos se registró fiebre. A un 73,6 por ciento de los pacientes se les solicitó hemograma preoperatorio. De éstos, un 67.9 por ciento presentó leucocitosis. Un 46,2 por ciento de los pacientes son intervenidos dentro de las primeras 24 horas de evolución. Sólo en un 22,6 por ciento el cirujano concluye en el intraoperatorio una apendicectomía en blanco, evidenciándose en 5 casos (4,7 por ciento) un cuadro diferente a patología apendicular. Se concluye que en una...

Analysis for transcript expression of meltrin alpha in normal, regenerating, and denervated rat muscle.

Meltrin alpha (a disintegrin and metalloprotease (ADAM) 12) is a recently discovered molecule of the metalloprotease-disintegrin family which has been shown to participate in myotube formation in vitro and in myogenesis in vivo. In this study we investigated meltrin alpha in regenerating rat muscle, which is a condition where satellite cells (SC) contribute to myofiber growth by fusing with one another and with myotubes or muscle fibers. We studied meltrin alpha mRNA expression by RT-PCR and in situ-hybridization in normal adult muscle, in soleus muscle regenerating for 2, 5, or 10 days, and in muscle which had been denervated 1 week, 4 weeks, or 6 months previously. SC do not fuse after denervation. They detach from the principal muscle fiber. Immunohistochemistry using an antibody against M-cadherin was performed in parallel in order to identify SC. Messenger RNA as revealed by RT-PCR was absent in normal adult muscle, but present in regenerating and also in denervated muscle. Meltrin alpha transcript detected by in situ-hybridization was present in regenerating muscle only, not in normal or denervated muscle. It was localized to SC. Taken together, meltrin alpha is absent in normal muscle, and localized to SC in fusing conditions. After denervation, the transcript is upregulated. However, it is so lowly abundant that it fails to be detected by in situ-hybridization. This expression profile suggests a role for meltrin alpha in the fusion of SC with myotubes or muscle fibers, but not in SC adhesion to the adjacent myofiber in normal adult muscle.

Allograft inflammatory factor-1 is expressed by macrophages in injured skeletal muscle and abrogates proliferation and differentiation of satellite cells.

Secretion of regulatory peptides by macrophages in injured skeletal muscle constitutes a pivotal determinator of tissue homeostasis. We analyzed expression of a novel Ca2+- binding peptide expressed by activated macrophages, the allograft inflammatory factor-1 (AIF-1), in rat devascularized skeletal muscle. AIF-1 expression was observed in 94% of all macrophages at the site of the injury 48 hours postdevascularization. The physiological function of AIF-1 in injured skeletal muscle was analyzed using a rat in-vitro model of satellite cell proliferation and differentiation. Addition of AIF-1 to the culture medium resulted in a concentration-dependent and reversible reduction of the total number of cells expressing M-cadherin (p < or = 0.0001), a mediator of the differentiation process of skeletal muscle cells, the proliferation associated PCNA (p < or = 0.0001), and the initiator of muscle differentiation myogenin (p < or = 0.0001). These results provide convincing evidence that activated AIF-1 expressing macrophages constitute the predominant cell type in skeletal muscle 48 hours postinjury, and that AIF-1 regulates reduced proliferation, differentiation, and activation of satellite cells.

Satellite cells as players and targets in normal and diseased muscle.

Satellite cells (SC), also termed adult myoblasts, are mononuclear cells of myogenic lineage. They are attached to the muscle fiber plasma membrane and surrounded by a common basement membrane. The characteristic localization differentiates them from embryonic and fetal myoblasts. SC are able to leave the G0 phase in which they usually reside in normal adult muscle, enter the mitotic cycle, and differentiate to express muscle-specific proteins. The activation of SC into the mitotic compartment and their progression to the differentiative compartment are processes which are tightly regulated by myogenic regulatory factors of the MyoD family and the cyclin-dependent kinases and their inhibitors. Those factors are in turn regulated by growth factors and innervation. SC are key features in muscle fiber growth, regeneration, and hypertrophy. Furthermore, they are targets in denervation atrophy, which results in SC loss in the long run. There is evidence from experimental work that SC age, and that they are a heterogeneous cell population in terms of mitotic cycle duration and have the ability to differentiate. Little is known of SC in human diseased muscle beyond their number. SC heterogeneity must be taken into account if future therapy strategies for muscular dystrophies are designed.

Satellite cells on isolated myofibers from normal and denervated adult rat muscle.

Satellite cells (SCs) in normal adult muscle are quiescent. They can enter the mitotic program when stimulated with growth factors such as basic FGF. Short-term denervation stimulates SC to enter the mitotic cycle in vivo, whereas long-term denervation depletes the SC pool. The molecular basis for the neural influence on SCs has not been established. We studied the phenotype and the proliferative capacity of SCs from muscle that had been denervated before being cultured in vitro. The expression of PCNA, myogenin, and muscle (M)-cadherin in SCs of normal and denervated muscle fibers was examined at the single-cell level by immunolabeling in a culture system of isolated rat muscle fibers with attached SCs. Immediately after plating (Day 0), neither PCNA nor myogenin was present on normal muscle fibers, but we detected an average of 0.5 M-cadherin(+) SCs per muscle fiber. The number of these M-cadherin(+) cells (which are negative for PCNA and myogenin) increased over the time course examined. A larger fraction of cells negative for M-cadherin underwent mitosis and expressed PCNA, followed by myogenin. The kinetics of SCs from muscle fibers denervated for 4 days before culturing were similar to those of normal controls. Denervation from 1 to 32 weeks before plating, however, suppressed PCNA and myogenin expression almost completely. The fraction of M-cadherin(+) (PCNA(-)/myogenin(-)) SCs was decreased after 1 week of denervation, increased above normal after denervation for 4 or 8 weeks, and decreased again after denervation for 16 or 32 weeks. We suggest that the M-cadherin(+) cells are nondividing SCs because they co-express neither PCNA or myogenin, whereas the cells positive for PCNA or myogenin (and negative for M-cadherin) have entered the mitotic cycle. SCs from denervated muscle were different from normal controls when denervated for 1 week or longer. The effect of denervation on the phenotypic modulation of SCs includes resistance to recruitment into the mitotic cycle under the conditions studied here and a robust extension of the nonproliferative compartment. These characteristics of SCs deprived of neural influence may account for the failure of denervated muscle to fully regenerate. (J Histochem Cytochem 47:1375-1383, 1999)