RESUMO
Mujer de 86 años, hipertensa, evaluada por 72 horas de pérdida de la conciencia luego de una caída súbita que no fue precedida por ningún síntoma. Durante el examen físico se encontraba hipotensa, sin respuesta al estímulo doloroso, con reflejos de tallo presentes. Durante la hospitalización permaneció hipotensa y necesitó soporte vasopresor. Despúes de un mes de hospitalización continuó sin respuesta. La IRM cerebral mostró eventos agudos isquémicos bilaterales tanto supra como infratentoriales (Figura 1). En la ecocardiografía se evidenció una fracción de eyección de 55% con un aneurisma del septum atrial con desplazamiento bilateral de 15 mm y un foramen oval permeable de 7 mm. El doppler de miembros inferiores fue normal. Discusión: Los infartos cerebrales limítrofes constituyen aproximadamente el 10% de todos los infartos cerebrales. Dichos infartos se pueden clasificar en externos (corticales) e internos (subcorticales). Cuando ambos se presentan en un mismo paciente, de forma bilateral y con compromiso tanto supratentorial como infratentorial, la causa más probable es la alteración hemodinámica y el pronóstico invariablemente es pobre.
A 86-year-old hypertensive woman was evaluated for 72 hours of unconsciousness after a sudden fall that was not preceded by any symptoms. Upon examination, she was hypotensive and unresponsive to pain. Brainstem reflexes were present. During hospitalization, she remained hypotensive and needing vasopressor support. After 1 month, she remained unresponsive. The MRI showed bilateral supratentorial and infratentorial accute ischemic strokes (Figure 1). The echocardiogram showed an ejection fraction of 55% and an atrial septal aneurysm with bilateral excursions of 15 mm and a patent foramen ovale of 7 mm. The doppler ultrasound of lower extremities was normal. Discussion: Watershed infarcts constitute approximately 10% of all brain infarcts. Two types are recognized: external (cortical) and internal (subcortical) and when both occur in association with bilateral, supratentorial and infratentorial infarcts, there is a higher probability of hemodynamic impairment, and the prognosis is invariably poor.
RESUMO
BACKGROUND: The obstruction of intracranial arteries causes cerebral hemodynamic impairment. It is now evident that patients with cerebral hemodynamic compromise have a higher risk of stroke than those with normal cerebral blood flow. The purpose of this study is to investigate the changes of cerebral blood flow and vascular reactivity after extra-intracranial arterial bypass (EIAB) surgery in patients with cerebral hemodynamic compromise. METHODS: We enrolled 16 consecutive patients (8 female and 8 male patients) with transient ischemic attack or cerebral infarction resulted from the occlusion of distal internal carotid artery (ICA) or middle cerebral artery (MCA). We measured the relative regional cerebral blood flow (rrCBF) at rest and after Diamox infusion, and vasomotor reactivity by using single photon emission computed tomography (SPECT). We performed extra-intracranial arterial bypass (EIAB) surgery in patients with impaired vasomotor reactivity. Follow-up brain SPECT was done at 3months after EIAB. We compared the rrCBF and vasomotor reactivity before and after EIAB, and evaluated the effect of collateral vessels on the cerebral hemodynamic after surgery. RESULTS: EIAB increases the vasomotor reactivity significantly (-19.6+/-10 before EIAB, 11.2+/-27 after EIAB, p=0.003) but does not increase the cerebral blood flow at rest (70.5% before EIAB, 70.9% after EIAB). The degree of collateral vessel development did not influence on the restoration of vasomotor reactivity. CONCLUSIONS: These results demonstrate that EIAB increases the vasomotor reactivity of the distal part on the occluded ICA or MCA, but does not increase the cerebral blood flow at rest.