INTRODUCCIÓN:La ecografía Doppler Duplex transcraneal es una técnica de exploración muy difundida en medicina humana por su gran utilidad en el campo de los cuidados intensivos, ya que permite estudiar de una forma no invasiva las patologías vasculares y sistémicas con repercusión en el sistema nervioso central. Además, dada su inocuidad y accesibilidad, se ha convertido no sólo en una técnica de diagnóstico, sino también en una herramienta muy útil para la monitorización de dichas patologías. Sin embargo, el Doppler Duplex color tranascraneal aún no se ha desarrollado en medicina veterinaria como un elemento práctico de uso clínico.MOTIVACIÓN DE LA TESIS:El objetivo de la realización de este trabajo es contribuir al estudio de la circulación sanguínea cerebral en la especie canina.DESARROLLO TEÓRICO:Se han utilizado 30 perros de diferente raza, edad y sexo, clínicamente sanos, a los que se les realizó ecografía Doppler Duplex Color Transcraneal a través de la ventana temporal, para la exploración de las arterias cerebrales rostral, media y posterior, tanto del lado izquierdo como del derecho (polígono de Willis), a través de la ventana suboccipital, para el estudio de la arteria basilar. Se realizó un análisis del espectro Doppler en cada vaso objeto de estudio, se evaluó el patrón de ondas y se midió la Vs, Vm, Vd, IR e IP. Los resultados obtenidos fueron: arteria cerebral rostral derecha: Vs = - 40,20 ± 6,90, Vm = - 25,89 ± 4,90, Vd = - 18,10 ± 3,87, IR = 0,57 ± 0,06 e IP = 0,87 ± 0,17; arteria cerebral rostral izquierda: Vs = -39,81 ¿ 4,10, Vm = -25,67 ± 5,13, Vd = - 17,64 ± 3,20, IR = 0,56 ± 0,07 e IP = 0,85 ± 0,19; arteria cerebral media derecha: Vs = 62,59 ± 10,90, Vm = 32,77 ± 9,13, Vd = 23,17 ± 6,53, IR = 0,65 ± 0,08 e IP = 1,27 ± 0,37; arteria cerebral media izquierda: Vs = 62,37 ± 9,10, Vm = 32,04 ± 7,82, Vd = 24,19 ± 6,63, IR = 0,64 ± 0,07 e IP= 1,22 ± 0,31; arteria cerebral caudal derecha: Vs = 36,35 ± 6,82, Vm = 18,97 ± 3,39, Vd = 15,48 ± 2,17, IR = 0,59 ± 0,05 e IP= 1,10 ¿ 0,20; arteria cerebral caudal izquierda: Vs = 34,31 ± 7,40, Vm= 19,26 ± 5,18, Vd = 15,49 ± 4,20, IR = 0,57 ± 0,05 e IP = 1,00 ± 0,20; arteria basilar: Vs = -74,53 ± 18,70, Vm = -34,26 ± 11,80, Vd = -22,81 ± 8,70, IR = 0,72 ± 0,07 e IP = 1,57 ± 0,36.Para facilitar la identificación de las arterias exploradas a través de la ventana temporal se realizaron maniobras de compresión carotídea. En la arteria cerebral rostral, tras la compresión en la arteria carótida ipsilateral, la velocidad de flujo se redujo en todos los perros entre un 20 y 50 %. En la arteria cerebral media, después de la compresión de la arteria carótida ipsilateral, la velocidad de flujo descendió en todos los perros entre un 20 y un 50 %. En las arterias cerebral caudal y basilar no se observaron cambios tras la compresión de la arteria carótida ipsilateral y carotídea respectivamente. Se han evaluado también los cambios hemodinámicos en la circulación cerebral tras la administración de 2 protocolos de sedación, medetomidina (40 µg/kg por vía intramuscular) y medetomidina (10 µg/kg vía intramuscular) combinada con butorfanol (0,2 mg/kg vía intramucular). Tras la sedación con ambos protocolos se observó una disminución en los valores de las Vs, Vm y Vd en la arteria cerebral media y una disminución de la Vs, IR e IP en la arteria basilar. Por último se han descrito los cambios hemodinámicos observados en las principales arterias de la base del cerebro en dos casos clínicos: un perro con encefalopatía hepática debida a un shunt portosistémico congénito, en el que se observó un aumento del IP en las arterias cerbral media derecha, cerebral media izquierda y basilar, relacionado con un aumento de la presión intracraneal y otro perro con un carcinoma nasal que se extendía hasta la porción rostral del cerebro. La ecografía Doppler transcraneal mostró valores elevados de Vs, Vm y Vd, así como valores disminuidos de IR e IP en las arterias rostrales derecha e izquierda y en la arteria cerebral media, pudiéndose interpretar como hiperemeia. Se pudo observar, además una evidente asimetría en el lado izquierdo donde se encontraba el tumor.CONCLUSIÓN:La ecografía Doppler transcraneal es una técnica de diagnóstico por imagen que puede realizarse en el perro. A través de la ventana temporal y ayudándose de la compresión en la arteria carótida ipsilateral se pueden explorar las arterias cerebrales rostral, media y caudal y usando la ventana suboccipital la arteria basilar. La exploración de las arterias de la base del cerebro en el perro mediante esta técnica, puede resultar útil para valorar cambios en la circulación cerebral tras la sedación con medetomidina o en patologías como el shunt portosistémico y neoplasias intracraneales.BIBLIOGRAFÍA:AASLID, R., MARKWALDER, T.M., NORMES, H. Non-invasive transcranial Doppler ultrasound recording of flow velocity in basal cerebral arteries. J Neurosurg., 1982; 57: 769- 774ABDO, A., LÓPEZ, O., FERNÁNDEZ, A. SANTOS, J. CASTILLO, J. CASTELLANOS, R. GONZÁLEZ, F. GÓMEZ, F. & LIMONTA, D. Transcranial Doppler Sonography in Fulminant Hepatic Failure. Transplant Proc 2003; 35: 1859-1860.AGGARWAL, S., BROOKS , D.M., KANG , Y, LINDEN , P.K. & PATZER, J.F. Noninvasive monitoring of cerebral perfusion pressure in patients with acute liver failure using transcranial doppler ultrasonography. Liver Transpl 2008; 14: 1048-1057.ALASTRUEY, J., PARKERB, K.H., PEIRÓ, J., BYRDC, S.M., SHERWIN, S.J. Modelling the circle of Willis to assess the effects of anatomical variations and occlusions on cerebral flows. J Biomech, 2006; 40: 1794-1805.ÁLVAREZ, J. Anatomía y fisiología de la circulación encefálica. En: Molina, C., Serena, J. y Alvarez, J. Ed. Manual de Doppler Transcraneal. Madrid: Aula Médica, 2000; 1-12.ANON. Protocol of amendment to the European Convention for the Protection of Vertebrate Animals used for Experimental and other Scientific Purposes. http://conventions.coe.int/treaties/html/170.htm. Accessed September 2, 2010.ANON. Boletin oficial del Estado (BCE) No 252. October 21, 2005, pp 34367-34391. http://www.umh.es/_web_rw/cere/docs/animales/1201_05%20proteccion%20animales%20experimentación.pdf. Accessed September 2, 2010.AVNER, A., DOBSON, J.M., SALES, J.I., HERRTAGE, M.E. Retrospective review of 50 canine nasal tumours evaluated by low-field magnetic resonance imaging. J Small Anim Pract, 2008; 49: 233-239.BAGLEY, R.S. Disease of the brain. En: Wheeler, S.J. 2ª Ed. Gloucestershire: BSAVA Manual of Small Animal Neurology.1995; 112-124. BARTRAM, D.H., DIAMOND, M.J., TUTE, A.S., TRAFFORD, A.W., JONES, R.S. Use of medetomidine and butorphanol for sedation in dogs. J Smal Anim Pract, 1994; 35: 495-498.BASS, A., KRUPSKI, W.C., DILLEY, R.B., BERSNTEIN, E.E., OTIS, S.M. Comparison of transcranial and cervical continuous wave Doppler in the evaluation of intracranial collateral circulation. Stroke, 1990; 21: 1584-1588.BATTON, D.G., HELLMANN, J., HERNANDEZ, M.J., MAISELS, M.J. Regional cerebral blood flow, cerebral blood velocity, and pulsatility index in newborn dogs. Pediatr Res, 1983; 17(11): 908-912.BAUMGARTNER, R.W., MATTLE, H.P., SCHROTH, G. Transcranial color-coded duplex sonography in the evaluation of collateral flow through the circle of Willis. Am J Neuroradiol, 1997; 18: 127¿133.BAUMGARTNER, R.W., ARNOLD, M., GÖNNER, F., STAIKOW, I., HERRMANN, C., RIVOIR, A., MÜRI, R.M. Contrast-enhanced transcranial color-coded duplex sonography in ischemic cerebrovascular disease. Stroke, 1997; 28: 2473-2478.BECKER, G., KRONE, A., KOULIS, D., LINDER, A., HOFMAN, E., ROGGENDORF, W., BOGDAHN, U. Reliability of transcranial colour-coded real-time sonography in assessment of brain tumours: correlation of ultrasound, computed tomography and biopsy findings. Neuroradiology, 1994; 36: 585-590.BECKER, G., KRONE, A., SCHMITT, K., WOYDT, M., HOFMANN, E., LINDNER, A., BOGDAHN, U., GAHN. G., ROOSEN, K.. Preoperative and postoperative follow-up in high-grade gliomas: comparison of transcranial color-coded real-time sonography and computed tomography findings. Ultrasound Med Biol, 1995; 21: 1123-1135.BELLNER, J., ROMMER, B., REINSTRUP, P., KRISTIANSSON, K-A, RYDING, E., BRANDT, L. Transcranial Doppler sonography pulsatility index (PI) reflects intracranial pressure (IPC). Surg Neurol, 2004; 62: 45-51.BISHOP, C.C., POWELL, S., RUTT, D., BROWSE, N.L. Transcranial Doppler measurement of middle cereberal artery blood flow velocity: a validation study. Stroke, 1983; 17: 913-915.BLEI, A. Monitoring cerebral blood flow: a useful clinical tool in acute liver failure? Liver Transpl 2005a; 11, 1320-1322.BLEI, A. The pathophyliology of brain edema in acute liver failure. Neurochemistry International 2005b; 47: 71-77.BLEI, A. Brain edema in acute liver failure: can it be prevented? Can it be treated? J Hepatol 2007; 46: 553-582.BRENNAN, R.W., HERNANDEZ, M.J., VANNUCCI, R. Cerebral blood flow and oxidative metabolism in the newborn dog. Acta Neurol Scand Suppl, 1977; 64: 424-425.BODE, H. Intracranial blood flow velocities during seizures and generalized epileptic discharges. Eur J Pediatr, 1992;151:706-709.BOGDAHN, U., BECKER, G., WINKLER, J., GREINER, K., PEREZ, J., MEURERS, B. Transcranial colour-coded real-time sonography in adults. Stroke., 1990; 21(12):1680-1688.BOGDAHN, U., FRÖHLICH, T., BECKER, G., KRONE, A., SCHLIEF, R., SCHÜRMANN, J., JACHIMCZAK, P., HOFMANN, E., ROGGENDORF, W., ROOSEN, K. Vascularization of primary central nervous system tumors: detection with contrast-enhanced transcranial color-coded real-time sonography. Radiology, 1994; 192:141-148.CABRER, C., DOMÍNGUEZ-ROLDAN, J.M., MANYALICH, M., TRIAS, E., PAREDES, D., NAVARRO, A., NICOLAS, J., VALERO, R., GARCÍA, C., RUIZ, A., VILARRODONA, A. Peristence of intracranial diastolic flow in transcranial Doppler sonography exploration of patients in brain death. Transplant Proc 2003; 35: 1642-2643. CARTER, J.E., CAMPBELL, N.B., POSNER, L.P., SWANSON, C. The hemodynamic effects of medetomidine continuous rate infusion in the dog. Vet Anaesth Analg, 2010; 37: 197-206.CARVALHO, C. F., CHAMMA, M. C., NETO ANDRADE, J. P. Transcranial duplex doppler ultrasonography in dogs with hydrocephalus Arq Bras Med Vet Zootec, 2010; 62: 54-63.CHAUDHURI. R., PADAYACHEE, T. S., LEWIS, R. R., GOSLING, R. G., COX, T. C. S. Non invasive assessment of the circle of Willis using transcranial pulsed Doppler ultrasound with angiographic correlation. Clin Radiol, 1992; 46: 193¿197.CHUNG, W., CHOI, H., LEE, K., LEE, H., CHOI, M., YOON, J. Quantitative evaluation of contrast enhanced trasncranial Doppler signal using galactose based echo-contrast agent in dogs. J Vet Med Sci, 2006; 68: 597-601. CLARKE, K.W., ENGLAND, G.C.W. Medetomidine, a new sedative-analgesic for use in the dog and its reversal with atipemazole. J Small Anim Pract, 1989; 30: 337-338.CLIMENT, S., BASCUAS, J. A. Sistema nervioso central. En: Cuadernos de anatomía y embriología veterinaria. 2ª Ed. Madrid: Marbán. 1989; 6: 116-118.CORDOBA, J., BLEI, A.T. Cerebral edema and intracranial pressure monitoring. Liver Transpl Surg, 1995; 1: 187-194.D¿ANJOU, M-A. The sonographic search for portosystemic shunts. Clin Tech Small Anim Prac 2007; 22: 104-114. DE BRAY, J.M., MISSOUM, A., DUBAS, F., EMILE, J., LHOSTE, P. Detection ofvertebrobasilar intracranial stenoses: transcranial Doppler sonography versus angiography. J Ultrasound Med, 1997; 16: 213-218.DEMCHUK, A.M., CHRISTOU, I., WEIN, T.H., FELBERG, R.A., MALKOFF, M., GROTTA, J.C. Accuracy and criteria for localizing arterial occlusion with transcranial Doppler. J Neuroimaging, 2000; 10:1-12.DEWEY, C.W. Emergency management of the head trauma patient. En: Vet Clin North Am., 2000; 30: 207-225.DOMÍNGUEZ, J.M., BARRERA, J.M., MARTIN, R., MURILLO, F., GARCÍA, C., RINCON, M.D. Changes in the intracranial pulse pressure waveform associated with brain death. Transplant Proc, 1999; 31: 2597-2598.DOMÍNGUEZ-ROLDÁN, J.M., GARCÍA-ALFARO, C., JIMÉNEZ-GONZALEZ, P.I., RIVERA-FERNÁNDEZ, V., HERNÁNDEZ-HAZANAS, F., PÉREZ-BERNAL, J. Brain death due to supratentorial masses: diagnosis using transcranial Doppler sonography. Transplant Proc., 2004a; 36 (10): 2898-2900.DOMÍNGUEZ-ROLDÁN, J.M., JIMÉNEZ-GONZÁLEZ, P.I., GARCÍA-ALFARO, C., RIVERA-FERNÁNDEZ, V. HERNÁNDEZ-HAZANAS, F. Diagnosis of brain death by transcranial Doppler sonography: solutions for cases of difficult sonic windows. Transplant Proc., 2004b; 36 (10): 2896-2897. DONE, S.H., PETER, C.G., EVANS, S.A., STICKLAND, N.C. Atlas en color de anatomía veterinaria: el perro y el gato. Madrid: Harcourt Brace de España, S.A, 1997.DONG, M.L., KOFKE, W.A., POLICARE, R.S., WANG, A.S., ACUFF, J., SEKHAR, L.N., JANNETTA, P.J. Transcranial Doppler ultrasonography in neurosurgery: effects of intracranial tumour on right middle cerebral artery flow velocity during induction of anaesthesia. Ultrasound in Med & Biol, 1996; 22: 1163-1168.DRUMMOND, J.C., DAO, A.V., ROTH, D.V., CHENG, C.R., ATWATER, B.I., MINOKADEH, A., PASCO, L.C., PATEL, P.M. Effect of dexmedetomidine on cerebral blood flow velocity, cerebral metabolic rate, and carbon dioxide response in normal humans. Anaesthesiology, 2008; 108: 225-232.DUQUE, F. J., DOMINGUEZ-ROLDAN, J. M., RUIZ, P., ZARAGOZA, C.& BARRERA-CHACON, R. Assessing circle of Willis blood circulation in dogs with transcranial color-coded duplex sonography. Vet Radiol Ultrasound 2009; 50: 530-535.DUQUE, F.J., BARRERA-CHACON, R., RUIZ. P., CASAMIAN-SORROSAL, D., ZARAGOZA, C., DOMINGUEZ-ROLDAN, J.M. The effect of transient carotid artery compression during transcranial Doppler ultrasonography exam in dogs. Vet Rec, 2010a; 167 (13): 481-484.DUQUE, F.J., BARRERA, R., RUIZ, P. ZARAGOZA, C., RENFREW, J.M., DOMINGUEZ, J.M. Changes of the blood flow in the middle cerebral artery and basilar artery during the status epilepticus. Two clinical cases. XXXV Annual World Small Animal Veterinary Association Congress. FECAVA / SVK-ASMPA / FAFVAC. Ginebra, 2-5 de Junio de 2010.DUQUE, J., DOMINGUEZ-ROLDAN, J.M., CASAMIAN-SORROSAL, D., BARRERA-CHACON, R. Transcranial Color-Coded Duplex Sonography in a dog with hepatic encephalopathy. Vet Radiol Ultrasound, 2011; 52(1): 111-113.DURHAM, J.R. Vascular ultrasound. En: Staren, E.D. Ed. Ultrasound for the surgeon. Philadephia : Lippincott-Raven Publishers. 1997; 109-122.EVANS, H.E. Miller¿s Anatomy of the dog. 3ª Ed. Philadelphia: W.B. Saunders Company. 1993. FASSBENDER, K., RIES, S., SCHMINKE, U., SCHNEIDER, S., HENNERICI, M. Inflamatory cytokines in CSF in bacterial meningitis: association with altered blood flow velocities in basal cerebral arteries. J Neurol Neurosurg Psychiatry 1996; 61: 57-61.FOX, F.R., PETRIE, J.P., HOHENHAUS, A.E. Peripheral vascular disease. En: Ettinger, J.S. y Feldman, E.C.. Textbook of veterinary internal medicine. Diseases of the dog and cat. 6ª Ed. Philadelphia: W.B. Saunders Company, 2005; 1145-1165.FUKUSHIMA, U., MIYASHITA, K., OKANO, S., HIGUCHI, S., TAKASE, K. Evaluation of intracranial pressure by transcranial Doppler ultrasonography in dogs with intracranial hypertension. J Vet Med Sci, 2000; 62 (3): 353-355.FUKUSHIMA, U., SASAKI, S., OKANO, S., TAKASE, K., HAGIO, M. The comparison between the cerebral blood flow directly measures and cerebral blood flow velocity in the middle and basilar cerebral arteries measured by transcranial Doppler ultrasonography. J Vet Med Sci, 1999; 61 (12):1293-1297.FUKUSHIMA, U., SASAKI, S., OKANO, S., OYAMADA, T., YOSHIKAWA, T., HAGIO, M., TAKASE, K. Non-invasive diagnosis of ischemic brain damage after cardiopulmonary resuscitation in dogs by using transcranial Doppler ultrasonography. Vet Radiol Ultrasound, 2000; 41 (2): 172-177.GARCÍA, R. Circulación por áreas especiales. En: García, A. et al. Ed: Fisiología Veterinaria. Madrid: McGraw-Hill. 1995; 372-379. GAROSI, L., McCONNELL, J. Ischaemic stroke in dogs and humans: a comparative review. J Small Anim Pract, 2005; 46 (11): 521-529.GOROSTIDI, A., TXOPERANA, F., ALBERDI, F., ZUBÍA, F., SEBASTIÁN, R., SAN MARTÍN, I. Evolución de la velocidad del flujo sanguíneo cerebral en las meningitis graves medida mediante Doppler transcraneal. Med Intensiva 2004; 28: 193-200.GIRAD, N.M., LEECE, E.A., CARDWELL, J.M., ADAMS, V.J., BREARLEY, J.C. The sedative effects of low-dose medetomidine and butorphanol alone and in combination intravenously in dogs. Vet Anaesth Analg, 2010; 37: 1-6.GONÇALVES, R., CARRERA, I., GAROSI, L., SMITH, P.M., FRASER MCCONNELL, J., PENDERIS, J. Clinical and topographic magnetic resonance imaging characteristics of suspected thalamic infarcts in 16 dogs. The Veterinary Journal, 2011; 188: 39-43.HOMAR J, ABADAL JM, LLOMPART-POU JA, PÉREZ-BÁRCENA J, IBÁÑEZ J. Hemodinámica cerebral en pacientes con traumatismo craneoencefálico evaluada por doppler transcraneal y duplex transcraneal con codificación en color. Estudio comparativo. Neurocirugía, 2007; 18: 221-226.HOKSBERGEN, A.W.J., FULESDI, B., LEGEMATE, D.A., CSIBA, L. Collateral configuration of the Circle of Willis. Transcranial Color-Coded Duplex ultrasonography and comparison with postmortem anatomy. Stroke, 2000; 31: 1346-1351.HOKSBERGEN, A.W.J., LEGEMATE, D.A., UBBINK, D.T., DE VOS, H.J., JACOBS, M.J.H.M. Influence of the collateral function of the circle of Willis on hemispherical perfusion during carotid oclusion as assessed by transcranial colour-coded duplex ultrasonography. Eur J Vasc Endovasc Surg, 1999; 17: 486¿492.HOKSBERGEN, A.W.J., MAJOIE, B.L., HULSMANS, F-J.H., LEGEMATE, D.A. Assessment of the collateral function of the circle the Willis: three-dimensional with transcranial color-coded duplex sonography. Am J Neuroradiol. 2003; 24: 456-462.HENDERSON, R.D., ELIASZIW, M., FOX, A.J., ROTHWELL, P.M., BARNETT, H.J.M. Angiographycally defined collateral circulation and risk of stroke in patients with severe carotid artery stenosis. Stroke., 2000; 31: 128¿132.HOLT, D. Hepatic and Splenic Emergencies. In: Textbook of Veterinary Internal Medicine. Eds: Ettinger S. J. & Feldman E. C. Elsevier Saunders, Missouri. 2005; 440-442.HOLT, D. Hepatic Encephalopathy. In: Small Animal Critical Care Medicine. Eds. D. Silverstein and Hopper K. Saunders. 2008; 438-441.HUDSON, J.A., BUXTON, D.F., COX, N.R., FINN-BODNER, S.T., SIMPSON, S.T., WRIGHT, J.C., WALLACE, S.S., MITRO, A. Color flow Doppler imaging and Doppler spectral analysis of the brain of neonatal dogs. Vet Radiol Ultrasound, 1997; 38 (4): 313-22.HUDSON, J.A., CARTEE, R.E., SIMPSON, S.T., BUXTON, D.F. Ultrasonographic anatomy of the canine brain. Vet Radiol, 1989; 30 (1): 13-21.HUNT, G.B., MALIK, C.R., BELLENGER, M.R., PEARSON, M.R.B. Total venous inflow occlusion in the normothermic dog: a study of hemodynamic, metabolic and neurological consequences. Res Vet Sci., 1992; 52: 371-377.IIDA, H., OHATA, H., IIDA, M., WATANABE, Y., DOHI, S. Direct effects of alpha(1)-and alpha(2)-adrenergic agonists on spinal and cerebral pial vessels in dogs. Anaesthesiology 1999; 91: 479-485.ISHIYAMA, T., DOHI, S., IIDA, H., WATANABE, Y., SHIMONAKA, H. Mechanisms of dexmedetomidine-induced cerebrovascular effects in canine in vivo experiments. Anaesth Analg, 1995; 81: 1208-1215.ITAMOTO, K., NAKAICHI, M., OKUDA, M., OTOI, T., INOKUMA, H., TAURA, Y. Effects of medetomidine and atipemazole on cerebral perfusion pressure in dogs. J Anim Vet Adv, 2010; 9: 913-919.JOSEPH, R.J., GREENLEE, P.G., CARRILLO, J.M., KAY, W.J. Canine cerebrovascular disease: Clinical and pathological findings in 17 cases. J Am Anim Hosp Assoc., 1988; 24: 569-576.KARLSSON, B.R., FORSMAN, M., ROALD, O., HEIER, M.S., STEEN, P.A. Effect of dexmedetomidine, a selective and potent alpha 2-agonist, on cerebral blooe flow and oxygen consumption during halothane anesthesia in dogs. Anaesth Analg, 1990; 71: 125-129.KASSEL, N.F., y LANGFITT, T.W. Variations in the circle of Willis in Macaca mulatta. Anat. Rec., 1965; 152: 257-264.KAPOOR, K., KAK, V.K., SINGH, B. Morphology and comparative anatomy of circulus arteriosus cerebri in mammals. Anat. Histol Embryol., 2003; 32: 347-355.KEEGAN, R.D., GREENE, S.A., BAGLEY, R.S., MOORE, M.P., WEIL, A.B., SHORT, C.E. Effects of medetomidine on intracranial pressure and cardiovascular variables of isoflurane-anesthetized dogs. Am J Vet Res, 1995; 193-198.KING, A.S. Arterial supply to the central nervous system. En: Physiological and clinical anatomy of the domestic mammals. Vol. 1. Central nervous system. Oxford: Oxford University Press, 1987; 1-12.KLINGELHÖFER, J., CONRAD, B., BENECKE, R., SANDER, D. & MARKAKIS, E. Evaluation of intracranial pressure from transcranial Doppler studies in cerebral disease. J Neurol 1988; 253: 159-162.KO, J.C., BAILEY, J.E., PABLO, L.S., HEATON-JONES, T.G. Comparison of sedative and cardiorespiratory effects of medetomidine and medetomidine-butorphanol combination in dogs. Am J Vet Res, 1996; 57: 535-540.KÖNIG, H.E., LIEBICH, H. Veterinary anatomy of domestic mammals. New York: Schattauer. 3ª ed. 2007.KRABBE-HARTKAMP, M.J., VAN DER GROND, J., DE LEEUW, F-E., ALGRA, A., HILLEN, B., BREBELER, M.M.B., MALI, W.P.T. Circle of Willlis: Morphologic variation on three-dimensional Time-of-Flight MR Angiograms. Radiology, 1998; 207: 103-111.KRAFT S, GAVIN P. Intracranial Neoplasia. Clin Tech Small Anim Pract, 1999; 14: 112-123.KWON, H-M., LEE, Y-S. Transcranial Doppler sonography evaluation of anterior cerebral artery hypoplasia or aplasia. J Neurol Sci. 2005; 231: 67-70. LAMB, C.R. Ultrasongraphy of portosystemic shunts in dogs and cats. Vet Clin North Am Small Anim Prac 1998; 28: 725-753.LANA, S.E., DERNELL, W.S., LAFFERTY, M.H., WITHROW, S.J., LARUE, S.M. Use of radiation and a slow-realease cisplatin formulation for treatment of nasal tumors. Vet Radiol Ultrasound, 2004; 45: 577-581.LARSEN, F. S., WENDON, J. Brain edema in liver failure: basic physiologic principles and management. Liver Transpl 2002; 11 : 983-989.LAZORTHES, G., GOUAZE, A., SANTINI, J.J., SALAMON, G. Le cercle arterial du cerveau (circulus arteriosus cerebri). Anat. Clinica, 1979; 1: 241-257.LEE, K., CHOI, M., YOON, J., JUNG, J. Spectral waveform analysis of major arteries in conscious dogs by Doppler ultrasonography. Vet Radiol Ultrasound., 2004; 45 (2): 166-171.LEE, K.C., CHO, M.C., YOON, J.H. Influence of isoflurane anesthesia on pulsatility index and peak systolic velocity of basilar artery in dogs by Doppler ultrasonography. J Vet Sci. 2002; 3 (3): 203-205.LEVI, C.R., GACS, Z., SCHWARTZ, R., HUDSON, P., HARDY, D., BULL, N. The accuracy of intracranial large artery occlusive disease assessment using transcranial colour coded duplex sonography. Stroke, 2000; 31: 336.LEVI, C.R., SELMES, C. Transcranial ultrasound-clinical applications in cerebral ischaemia. Australian Prescriber, 2001; 24: 137-140.LINDEGAARD, K.E., BAKKE, S.J., GROLIMUND, P., AASLID, R., HUBER, P., NORNES, H. Assessment of intracranial hemodynamics in carotid artery disease by transcranial Doppler ultrasound. J Neurosurg, 1985; 63: 890-898. LLOMPART POU, A., ABADAL CENTELLAS, J.M., AYESTARÁN ROTA, J.I., JORDÁ MARCOS, R., IBÁÑEZ JUVÉ, J. Meningitis bacteriana aguda con hipertensión endocraneal. Med Intensiva, 2003; 27:498-500.MADDERN, K., ADAMS, V.J., HILL, N.A., LEECE, E.A. Alfaxalone induction dose following administration of medetomidine and butorphanol in the dog. Vet Anaesth Analg, 2010; 37: 7-13.MADDISON, J. E. Hepatic encephalopathy. J Vet Intern Med 1992; 6: 341-353.MALINOWSKI, C. Canine and feline nasal neoplasia. Clin Tech Small Anim Pract 2006; 21:89-94.MAST, H., ECKER, S., MARX., P. Cerebral ischemia induced by compression test during transcranial Doppler sonography. Clin Investig 1993; 71: 46-48.MATHEWS, K. G., BUNCH, S. K. Vascular Liver Diseases. In: Textbook of Veterinary Internal Medicine. Eds: Ettinger S. J. & Feldman E. C. Elsevier Saunders, Missouri. 2005; 1453-1464.McPHERSON, R.W., KOEHLER, R.C., KIRSCH, J.R., TRAYSTMAN, R.J. Intraventricular dexmedetomidine decreases cerebral blood flow during normoxia nad hypoxia in dogs. Anaesth Analg, 1997; 84:139-147.MELLEMA, L., KOBLIK, P., KORTZ, G., LECOUTEUR, R.A., CHECHOWITZ, M.A., DICKINSON, P.J. Reversibel magnetic resonance Imaging abnormalities in dogs following seizures. Vet Radiol Ultrasound, 2005; 40: 588-595.MENDÍA GOROSTIDI, A., TXOPERENA, G., ALBERDI, F., ZUBIA, F., SEBASTIAN, R., SANMARTIN, E.I. Evolución de la velocidad del flujo sanguíneo cerebral en las meningitis graves mediante Doppler transcraneal. Med Intensiva, 2004; 28: 193-200.MILLER, M.E., CHRISTENSEN, G.C., EVANS, H.E. Anatomy of the dog. Philadelphia: W.B. Saunders. 1967; 310-316MIÑO, N., ESPINO, L., BARRERIRO, A. Effects of medetomidine on Doppler variables of major abdominal arteries in normal dogs. Vet Res Commun, 2008; 32: 175-186.MOLINA, C. Valoración del estado de la microcirculación cerebral en pacientes con infartos lacunares mediante el estudio de la reactividad cerebrovascular por Doppler transcraneal. Tesis Doctoral. Universidad Autónoma de Barcelona.1999.MOLINA, C. Ecopotenciadores en el estudio de la circulación cerebral por Doppler transcraneal. En: Molina, C., Serena, J., Alvarez, J. Manual de Doppler Transcraneal. Madrid: Aula Médica, 2000.MOLTÓ, J.M. Localización de los principales vasos mediante Doppler transcraneal. En: Molina, C., Serena, J., Alvarez, J. Manual de Doppler Transcraneal. Madrid: Aula Médica, 2000; 33-49.MOPPET, I.K., MAHAJAN, R.P. Transcranial Doppler ultrasonography in anaesthesia an intensive care. Br J Anaesth, 2004; 93: 710-724.MUIR, W.W. III, FORD, J.L., KARPA, G.E., HARRISON, E.E., GADAWSKI, J.E. Effects of intramuscular administration of low doses of medetomidine and medetomidine-butorphanol in middle-agged and old dogs. JAVMA, 1999; 215: 1116-1120. MÜLLER, M., HERMES, M., BRÜCKMAN, H., SCHIMRIGK, K. Transcranial Doppler ultrasound in the evaluation of collateral blood flow in patients with internal carotid artery occlusion: correlation with cerebral angiography. Am J Neuroradiol, 1995; 16: 195¿202.NAGAI, H., MORITAKE, K., TAKAYA, M. Correlation between transcranial hypertension. Stroke, 1997; 28; 603¿608.NYLAND, T.G., MATTOON, J.S., HERRGESELL, E.J., WISNER, E.R. Principios físicos, equipos y seguridad del diagnóstico ecográfico. En: Nyland, T.G. y Mattoon, J.S. Diagnóstico Ecográfico en pequeños animals. Barcelona: Multimédica Ediciones Veterinarias. 2004; 1-21.OHATA, H., IIDA, H., DOHI, S., WATANABE, Y. Intravenous dexmedetomidine inhibits cerebrovascular dilation iduced by isoflurane and sevoflurane in dogs. Anaesth Analg, 1999; 89: 370-377.OLIVER J, LORENZ M, KORNEGAY J. Manual de Neurología Veterinaria. 3ª Ed. Multimédica Ediciones Veterinarias, 2003.PADAYACHEE, T.S., KIRKHAM, E.J., LEWIS, R.R., GILLARD, J., HUTCHINSON, M.C., GOSLING, R.C. Transcranial measurement of blood velocities in the basal cerebral arteries using pulsed Doppler ultrasound: a method of assessing the Circle of Willis. Ultrasound Med Biol, 1986; 12: 5-14.PATNAIK, A.K. Canine nasal and paranasal sinus neoplasms: clinicopathological study of 285 cases. JAAHA 1989; 25: 103-114.PEREZ, R.B., CARVALHO C.F. Características ultrassonográficas da meningoencefalite granulomatosa em cães. Clínica Veterinária, 2009; 80: 20 ¿ 26. PETITE, A.F.B., DENNIS, R. Comparison of radiography and magnetic resonance imaging for evaluation the extent of nasal neoplasia in dogs. J Small Anim Pract, 2006; 47: 529-536.PLATT, S., GAROSÍ, L. Canine cerebrovascular disease: do dogs have strokes?. J Am Anim Hosp Assoc., 2003; 39 (4): 337- 342.PLATT, S., OLBY, N.J. BSAVA manual of Canine and Feline Neurology. 3ª Ed. BSAVA publications. Gloucester, U.K., 2004 PODELL, M. Neurologic Manifestations of Systemic Disease. In: Textbook of Veterinary Internal Medicine. Eds: Ettinger S. J. & Feldman E. C. Elsevier Saunders, Missouri. 2005; 798-802.POULSEN, C. Physical Principles. En : Poulsen C, Tobias R. An Atlas and textbook of diagnostic ultrasnography of the dog and cat. Manson Publishing Ltd., 2000; 21-30.PRIELIPP, R.C., WALL, M.H., TOBIN, J.R., GROBAN, L., CANNON, M.A., FAHEY, F.H., GAGE, H.D., STUMP, D.A., JAMES, R.L., BENNETT, J., BUTTERWORTH, J. Dexmedetomidine-induced sedation in volunteers decrases regional and global cerebral blood flow. Anesth Analg, 2002; 95: 1052-1059.RAUSER, P., LEXMAULOVA, L. Clinical comparison of medetomidine-butorphanol and medetomidine-buprenorphine combinations for intravenous premedication of general anaesthesia in the dog. Acta Vet, 2002; 71: 69-76.RIES, S., SCHMINKE, U., FASSBENDER, K., DAFERTSHOFFER, K., STEINKE, W., HENERICI, M. Cerebrovascular involvement in the acute phase of bacterial meningitis. J Neurol, 1997; 244: 51-55.ROPPER, A., MARTIN, A. S. Adams & Victor¿s Principles of Neurology. 9ª Ed McGraw- Hill, 2009.ROTHUIZEN, J. Liver. In: Small Animal Gastroenterology. Ed. Steiner, J. M. Schlütersche, Hannover. 2008; 241-281.SAITO, M., OLBY, N.J., SPAULDING, K., MUNAMA, K., SHARP, N.J. Relationship among basilar artery resistance index, degree of ventriculomegaly, and clinical signs in hydrocephalic dogs. Vet Radiol Ultrasound., 2003; 44 (6): 687-694.SÁNCHEZ, G. Síndrome de hipertensión intracraneal. En: Pelegrino, F., Suraniti, A y Garibaldi, L. El libro de neurología para la práctica clínica. Buenos Aires, Argentina: Intermedica Editorial, 2003; 309-318.SCHNEIDER, P.A., ROSSMAN, M.E., TOREM, S., OTIS, S.M., DILLERY, R.B., BERNSTEIN, E.F. Transcranial Doppler in the management of extracranial cerebrovascular disease: implications in diagnosis and monitoring. J Vasc Surg, 1988; 7: 223-231.SEO, M., CHOI, H., LEE, K., CHOI, M., YOON, J. Transcranial Doppler ultrasound analysis of resistive index in rostral and caudal cerebral arteries in dogs. J Vet Sci, 2005; 6 (1) : 61¿66.SINCLAIR, M.D. A review of the physiological effects of alpha 2-agonist related to the clinical use of medetomidine in small animal practice. Can Vet J, 2003; 44: 885-897.SMIELEWSKI, P., CZOSNYKA, M., KIRKPATRICK, P., MCEROY, H., RUTKOWSKA, H., PICKARD, J.D. Assessment of cerebral autorregulation using carotid artery compression. Stroke, 1996; 27: 2197-2203.SNYDER, J.M., LIPITZ, L., SKORUPSKI, K.A., SHOFER, F.S., VAN WINKLE, T.J. Secondary intracranial neoplasia in the dog: 177 cases (1986-2003). J Vet Intern Med 2008; 22: 172-177.SORIANO, G., GÁLLEGO, J., IRIGOYEN, M.E., AYMERICH, N. Neurosonology and stroke. Anales Sis San Navarra, 2000; 23 (Supl.3): 67-77. STEPIEN, R.L., RAPPORT, G.S., HENIK, R.A., WENHOLZ, L., THOMAS, C.B. Comparative diagnostic test characteristics of oscillometric and Doppler ultrasound methods in the detection of systolic hypertension in dogs. J Vet Intern Med., 2003; 17: 65-72.STOPEN, M.E., BAROIS, V., CONTRERAS, E. Ultrasonidos. En: Pedrosa, C y Casnova, R. Eds. Diagnóstico por imagen, 2ª ed. Madrid: McGraw-Hill/Interamericana. 1997; 135-155.SZATMARI, V., ROTHUIZEN, J. Ultrasonographic identification and characterization of congenital portosystemic shunts and portal hypertensive disorders in dogs and cats. In: Standards for clinical and histological diagnosis of canine and feline liver diseases. Eds: Rothuizen, J., Bunch, S. E., Charles, J. A., Cullen, J. M., Desmet, V. J., Szatmári, V., Twedt, D. C., Van den Ingh, T. S. G. A. M., Winkle, T. V. & Washabau R. J. Elsevier, Philadelphia, USA. 2006; 15-39.TODA, N. Alpha adrenergic receptor subtypes in human, monkey and dog cerebral arteries. J Vet Pharmacol Ther, 1983; 226: 861-868.TOFTENG, F., LARSEN, F.S. Management of patients with fulminant hepatic failure and brain edema. Metab Brain Dis, 2004; 19: 207-214.TORISU, S., WASHIZU, M., HASEGAWA, K. & ORIMA, H. Brain magnetic resonante Imaging characteristics in dogs and cats with congenital portosystemic shunts. Vet Radiol Ultrasound, 2005; 46, 447-451.TOTBOUL, P.J., ARBEILLE, Ph. Vasos cervicales y cefálicos. Eds.: Exploración neurovascular con ultrasonidos. París: Masson, S.A. 1992; 1-22.TUREK, M.M., LANA, S.E. Canine nasosinal tumors. In: Withrow, S.J., Vail, D.M., editors. Small Animal Clinical Oncology. Saunders; 2006. p. 525-539.VAN DER ZWAN, A., HILLEN, B., TULLEKEN, CAF., DUJOVNY, M., DRAGOVIC, I. Variability of the territories of the major cerebral arteries. J Neurosurg, 1992; 77: 927-940.WAELBERS, T., PEREMANS, K., VERMEIRE, S., DUCHATEAU, L., DOBBELEIR, A., AUDENAERT, K., POLIS, I. The effects of medetomidine on the regional cerebral blood flow in dogs measured using Technetium-99m-Ethyl Cysteinate Dimer SPECT. Res Vet Sci, 2011; 91: 138-143.WELLENS, D., WOUTERS, R., DE REESE, P., BEIRNAERT., P., RENEMAN, R.. The cerebral blood distribution in dogs and cats. An anatomical and functional study. Brain Res., 1975; 86: 429-438.WERNER, C., CHRISTIAN, R., HOOFMAN, W.E., KOCHS, E., ALBERCHT, R., ESCH, J.S. The effects of propofol on cerebral blood flow in correlation to cerebral blood flow velocity in dogs. J Neurosurg Anesthesiol, 1992; 4 (1): 41-46. WERNER, C., HOFFMAN, W.E., KOCHS, E., ALBRECHT, R.F. Transcranial Doppler sonography indicates critical brain perfusion during hemorrhagic hypotension in dogs. Anesth Analg., 1995; 81 (6): 1203-1207.WERNER, C., HOFFMAN, W.E., BAUGMAN, V.L., ALBRECHT, R.F. Effects of sufentanil on cerebral blood flow, cerebral blood flow velocity, and metabolism in dogs. Anesth Analg, 1991; 72 (2): 177-181.WERNERN, C., KOCHS, E., HOFFMAN, W.E., BLANC, I.F. Cerebral blood flow and cerebral blood flow velocity during angiotensin-induced arterial hypertension in dogs. Can J Anaesth, 1993; 40 (8): 755-760. WESSMANN, A., CHANDLER, K., GAROSI, L. Ischaemic and haemorrhagic stroke in the dog. Vet J, 2009; 180: 290-303.WILDER-SMITH, E., NIRKKO, A.C. Contribution of concurrent Doppler and EEG in differentiating occipital epileptic discharges from migraine. Neurology, 1991; 41: 2005-2007.WHITE, H. & VENKATESH, B. (2006) Applications of transcranial Doppler in the ICU: a review. Intensive Care Medicine 32, 981-994.YIKILMAZ, A., TAYLOR, G.A. Sonographic findings in bacterial meningitis in neonates and young infants. Pediatr Radiol, 2008; 38: 129-137.YOUNG, L.E., BREARLEY, J.C., RICHARDS, D.L.S. Medetomidine as a premedicant in dogs and its reversal by atipamezole. J Small Anim Pract, 1990; 31: 554-559.ZORNOW, M.H., MAZE, M., DYCK, J.B., SHAFER, S.L. Dexmedetomidine decreases cerebral blood flow velocity in humans. J Cereb Blood Flow Metab, 1993; 13: 350-353.ZORNOW, M.H., FLEISCHER, J.E., SCHELLER, M.S., NAKAKIMURA, K., DRUMMOND, J.C. Dexmedetomidine, an alpha 2-adrenergic agonist, decreases cerebral blood flow in the isoflurane-anesthetized dog. Anesth Analg, 1990; 70: 624-630.
