Revascularization improves vascular hemodynamics - a study assessing cerebrovascular reserve and transit time in Moyamoya patients using MRI.

Cerebrovascular reserve (CVR) reflects the capacity of cerebral blood flow (CBF) to change. Decreased CVR implies poor hemodynamics and is linked to a higher risk for stroke. Revascularization has been shown to improve CBF in patients with vasculopathy such as Moyamoya disease. Dynamic susceptibility contrast (DSC) can measure transit time to evaluate patients suspected of stroke. Arterial spin labeling (ASL) is a non-invasive technique for CBF, CVR, and arterial transit time (ATT) measurements. Here, we investigate the change in hemodynamics 4-12 months after extracranial-to-intracranial direct bypass in 52 Moyamoya patients using ASL with single and multiple post-labeling delays (PLD). Images were collected using ASL and DSC with acetazolamide. CVR, CBF, ATT, and time-to-maximum (Tmax) were measured in different flow territories. Results showed that hemodynamics improved significantly in regions affected by arterial occlusions after revascularization. CVR increased by 16 ± 11% (p < 0.01) and 25 ± 13% (p < 0.01) for single- and multi-PLD ASL, respectively. Transit time measured by multi-PLD ASL and post-vasodilation DSC reduced by 13 ± 7% (p < 0.01) and 9 ± 5% (p < 0.01), respectively. For all regions, ATT correlated significantly with Tmax (R2 = 0.59, p < 0.01). Thus, revascularization improved CVR and decreased transit times. Multi-PLD ASL can serve as an effective and non-invasive modality to examine vascular hemodynamics in Moyamoya patients.

Traumatic chiasmal syndrome. Case report / Síndrome quiasmática traumática. Relato de caso

ABSTRACT Traumatic chiasmal syndrome is one of the rare etiologies of chiasmal syndrome, characterized by optic chiasm injury following head trauma. The main visual defect associated is bitemporal hemianopia with macular splitting; however, it can present with a variety of other visual defects and neurologic signs. The authors report a case of complete bitemporal hemianopia after head trauma, with multiple frontal and skull base fractures and no other neurologic deficits, or hypothalamic-pituitary abnormality. Most cases of traumatic chiasmal syndrome are caused by mechanical stretch or compression of the chiasma. Nevertheless, in this case, the radiologic findings excluded macroscopic disruption or external compression of the chiasma, raising the possibility of a contusion necrosis associated with functional impairment of the optic chiasma. Traumatic chiasmal syndrome must be considered in the differential diagnosis of patients presenting with complete bitemporal hemianopia after head injury caused by frontal and skull base fracture.

RESUMO A síndrome quiasmática traumática é uma das raras etiologias da síndrome do quiasma óptico, que se caracteriza pela presença de lesão do quiasma óptico causada por traumatismo craniencefálico. O principal defeito visual associado é a hemianopsia bitemporal com macular splitting. No entanto, pode se manifestar por uma variedade de outros defeitos visuais e sinais neurológicos. Os autores relatam um caso de hemianopsia bitemporal completa após traumatismo craniencefálico com múltiplas fraturas frontais e da base do crânio na ausência de outros défices neurológicos ou alterações do eixo hipotálamo-hipofisário. A maioria dos casos de síndrome quiasmática traumática é causada por estiramento mecânico ou compressão do quiasma. No entanto, no caso apresentado, os achados radiológicos excluíram lesão macroscópica ou compressiva do quiasma, levantando a possibilidade de uma necrose após contusão associada ao compromisso funcional do quiasma óptico. A síndrome quiasmática traumática deve ser considerada no diagnóstico diferencial de doentes que apresentam hemianopsia bitemporal completa após traumatismo craniencefálico, especialmente em casos de fratura do osso frontal e da base do crânio.