[The two faces of veno-arteriolar reflex: cutaneous vasodilatation and vasoconstriction to raise and to lower the arm]. / Las dos caras del reflejo venoarteriolar: vasoconstriccion y vasodilatacion cutanea al bajar y subir el brazo.

INTRODUCTION: The veno-arteriolar reflex (VAR) is triggered by an increase in the transmural venous pressure on placing a part of the body in the same direction as the gravitational acceleration below the heart. AIM: To assess the VAR in healthy subjects on raising a part of the body above the level of the heart. SUBJECTS AND METHODS: VAR was studied in 16 healthy subjects (20-65 years old) by means of changes in the blood flow in the skin detected using a digital infrared photoplethysmograph attached to the fingertip under the following conditions: right arm at the height of the heart, right arm below the heart and right arm below the level of the heart. The variables measured were: amplitude of the blood flow in the skin with the arm raised to the height of the heart (baseline amplitude), percentage decrease of the blood flow in the skin with the arm below the heart and percentage increase in blood flow with the arm above the heart. RESULTS: The percentage of vasoconstriction with the right arm below the heart was 35%, and that of vasodilation, 50%. CONCLUSIONS: Evaluation of the VAR with the arm below the heart causes vasoconstriction, and elevation of the arm causes an important degree of vasodilation. Vasoconstriction and vasodilation are maintained while the limb is kept above or below the heart. This is an economical and potentially very useful way of studying the innervation of the microcirculation in a number of different peripheral neuropathies of thin and mixed fibres.

TITLE: Las dos caras del reflejo venoarteriolar: vasoconstriccion y vasodilatacion cutanea al bajar y subir el brazo.Introduccion. El reflejo venoarteriolar (RVA) lo provoca un incremento en la presion venosa transmural al colocar una parte del cuerpo en el sentido de la aceleracion gravitatoria por debajo del corazon. Objetivo. Evaluar el RVA en sujetos sanos al levantar una parte del cuerpo por encima del corazon. Sujetos y metodos. En 16 sujetos sanos (20-65 años) se estudio el RVA mediante cambios en el flujo sanguineo de la piel con un fotopletismografo digital infrarrojo colocado en el pulpejo en sujetos sanos durante las siguientes condiciones: brazo derecho a la altura del corazon, brazo derecho 40 cm por debajo del corazon y brazo derecho 40 cm por encima del corazon. Las variables medidas fueron: amplitud del flujo sanguineo de la piel con el brazo a la altura del corazon (amplitud basal), porcentaje de disminucion del flujo sanguineo de la piel con el brazo por debajo del corazon y porcentaje de aumento del flujo sanguineo de la piel con el brazo por encima del corazon. Resultados. El porcentaje de vasoconstriccion con el brazo derecho por debajo del corazon fue del 35%, y el de vasodilatacion, del 50%. Conclusiones. La evaluacion del RVA con el brazo por debajo del corazon provoca vasoconstriccion, y la elevacion del brazo produce una importante vasodilatacion. La vasoconstriccion y la vasodilatacion se mantienen mientras la extremidad se mantenga por encima o por debajo del corazon. Este es un estudio potencialmente muy util y economico para estudiar la inervacion de la microcirculacion en diversas neuropatias perifericas de fibras delgadas y mixtas.

[Electroencephalographic normal variants or with uncertain significance]. / Variantes normales o de significado incierto en el electroencefalograma.

Electroencephalography is an important tool in the diagnosis of primary or secondary disorders of central nervous system, epilepsy is one of the most important. Sometimes normal electroencephalographic activity simulates epileptiform activity. This activity does not have pathological value and is considered a variant of normal brain activity. The main groups based on the classification proposed by Blum and Cervone are: rhythmic patterns; epileptiform patterns; lambda waves, and age dependent changes. These changes are frequently seen during drowsiness, sleep and during activation maneuvers and more common in children and adolescents. The aim of this review is to present the most important characteristics of each of these variants, in order to prevent them being confused with abnormal brain activity.