Near Infrared Spectroscopy and Transcranial Doppler in Monohemispheric Stroke

Abstract

We simultaneously performed near infrared spectroscopy (NIRS) and transcranial Doppler (TCD) to evaluate the effects of hypercapnia as well as of scalp ischemia on the blood flow at two different depth levels within the brain and of the scalp vessels. A decrease in the backscattered light intensity, meaning an increment of blood volume, was detected at the end of hypercapnia in all healthy subjects. This decrement was partly masked by ischemia in the cutaneous vessels. In 2 patients with a monohemispheric lesion in the middle cerebral artery (MCA) territory, an increase in NIRS response was found in the healthy hemisphere, while in the stroke side the CO₂-induced changes were negligible. TCD data showed a similar increment of blood flow velocity to the hypercapnia in both hemispheres, with no differences between the affected and normal side in 1 patient, whereas in the second one, no increment was observed on the affected side, probably due to internal carotid artery stenosis. The two methods nicely integrate: TCD mainly tests subcortical changes in the MCA flow, while NIRS is exquisitely sensitive to cortical arterioles and capillary blood flow modifications.

Near-infrared measurements of brain oxygenation in stroke

“…[9][10][11][12][13] This paper shows that fdNIRS can provide novel data allowing for comparison of individual stroke patients and stroke evolution.…”

“…8,9 This method can measure changes in NIRS parameters from a baseline but cannot obtain absolute values of each parameter, which is needed to compare oxygenation levels between the right and left side of an interrogated tissue, between subjects, or with an individual subject over days. Studies of acute stroke using cwNIRS have thus focused on variations of the NIRS signal according to head position, 10 side to side difference of low-frequency oscillations of the signal, 11 and change over time in various situations.…”

Diffuse optical imaging of brain activation: approaches to optimizing image sensitivity, resolution, and accuracy

“…They have employed the technique to study cerebral response to visual Ruben et al, 1997), auditory (Sakatani et al, 1999), and somatosensory Obrig et al, 1996) stimuli; other areas of investigation have included the motor system (Colier et al, 1999;Hirth et al, 1996;Kleinschmidt et al, 1996) and language (Sato et al, 1999). Still other researchers have addressed the prevention and treatment of seizures (Adelson et al, 1999;Sokol et al, 2000;Steinhoff et al, 1996;Watanabe et al, 2000) and psychiatric concerns such as depression (Eschweiler et al, 2000;Matsuo et al, 2000;Okada et al, 1996b), Alzheimer disease (Fallgatter et al, 1997;Hanlon et al, 1999;Hock et al, 1996), and schizophrenia (Fallgatter and Strik, 2000;Okada et al, 1994), as well as stroke rehabilitation (Chen et al, 2000;Nemoto et al, 2000;Saitou et al, 2000;Vernieri et al, 1999).…”

Dynamic physiological modeling for functional diffuse optical tomography

“…Clinical and research applications of DOT arise due to its specificity to the physiologically relevant chromophores HbO and HbR. Potential clinical and research applications for DOT abound in brain injury (Vernieri et al, 1999;Chen et al, 2000;Nemoto et al, 2000;Saitou et al, 2000), neurological diseases (Hock et al, 1996;Fallgatter et al, 1997;Hanlon et al, 1999;Steinhoff et al, 1996;Adelson et al, 1999;Sokol et al, 2000;Watanabe et al, 2000), psychiatric disorders (Okada et al, 1996b;Eschweiler et al, 2000;Matsuo et al, 2000;Okada et al, 1994;Fallgatter and Strik, 2000) and in cognitive and behavioral neuroscience (Ruben et al, 1997;Sakatani et al, 1999;Franceschini et al, 2003;Colier et al, 1999;Sato et al, 1999). Other research areas for DOT include infant monitoring (Chen et al, 2002;Hintz et al, 2001;Meek et al, 1999;Baird et al, 2002;Pena et al, 2003;Taga et al, 2003) and breast cancer detection Shah et al, 2004;Dehghani et al, 2003;Srinivasan et al, 2003).…”