Objective-Blood oxygenation level dependent (BOLD) contrast functional MRI images show activated cortical areas by detecting a reduced concentration of deoxyhaemoglobin (deoxy-Hb) during neuronal activity; however, near infrared spectroscopy (NIRS) has shown various patterns of cerebral blood oxygenation (CBO) changes in the frontal lobe during cognitive tasks. To determine if various patterns of CBO changes occur in the frontal lobe when the brain is directly stimulated, changes in CBO in the frontal lobe induced by deep brain stimulation in patients with implanted electrodes were evaluated. Methods-Six patients were studied, including five with Parkinson's disease and one with essential tremor. To reduce tremor or rigidity, the electrodes were implanted at the thalamic nucleus ventralis intermedius (VIM: three Parkinson's disease and one essential tremor) or the globus pallidus internus (GPi: two Parkinson's disease). Using NIRS, changes of deoxy-Hb, oxyhaemoglobin (oxy-Hb) and total haemoglobin (total Hb) were measured in the bilateral frontal lobes during various stimulus conditions. Results-High frequency (120 Hz) GPi stimulation consistently increased oxy-Hb and total Hb with a decrease of deoxy-Hb in an intensity and time dependent manner. Oxy-Hb and total Hb increased immediately after the onset of stimulation and then gradually decreased when stimulation was continued. By contrast, high frequency (120 Hz) VIM stimulation decreased oxy-Hb, deoxy Hb and total Hb in an intensity dependent manner. In the severe tremor patient with VIM stimulation, frequency response was examined by decreasing stimulus frequencies; deoxy-Hb increased at high frequencies (70-40 Hz), and then decreased below the control level at low frequencies (30-0 Hz), whereas oxy-Hb and total Hb increased consistently at high and low frequencies. Conclusion-The electrical stimulation of GPi and VIM caused various CBO changes in the frontal lobe, which were similar to those found during cognitive tasks. Such a multiplicity of CBO changes in the frontal lobe may be caused by complex neuronal circuits in the frontal lobe which has many neuronal connections to other cortical areas or the basal ganglia. (J Neurol Neurosurg Psychiatry 1999;67:769-773) Keywords: Blood oxygenation level dependent (BOLD) images; functional MRI; near infrared spectroscopy; Parkinson's disease Blood oxygenation level dependent (BOLD) contrast functional MRI images activating cortical areas by detecting a reduced concentration of deoxyhaemoglobin (deoxy-Hb) during neuronal activity. 1 PET activation studies on visual 2 or somatosensory functions 3 4 showed that brain activation causes a much greater increase in regional cerebral blood flow (rCBF) than O 2 consumption in the activating area, which leads to a decrease in deoxy-Hb. However, recent neuronal activation studies using near infrared spectroscopy (NIRS) have shown that, in addition to this cerebral blood oxygenation (CBO) change, cognitive tasks cause various patterns of changes in CBO in the frontal lobe. [5] [6] [7] [8] [9] NIRS is an optical method to measure concentration changes of oxyhaemoglobin (oxyHb) and deoxy-Hb in cerebral vessels by means of the characteristic absorption spectra of haemoglobin in the near infrared range. 10 NIRS activation studies have shown that neuronal activation generally causes increases in oxy-Hb and total haemoglobin (total Hb) with a decrease of deoxy-Hb at the activated cortical area [5] [6] [7] [8] [9] [10] [11] ; this change in CBO is consistent with that obtained by PET or functional MRI. In addition to this CBO change, NIRS activation studies have disclosed several patterns of changes in CBO in the frontal lobe during cognitive functions, such as decreases of oxy-Hb and total Hb or an increase of deoxy-Hb associated with increases of oxy-Hb and total Hb. However, it is not yet clear whether these CBO changes in the frontal lobe were specific to cognitive tasks. In addition, the relation between the CBO changes and stimulus conditions such as stimulus frequency and intensity has not been elucidated in the frontal lobe. Recently, deep brain stimulation therapies, such as electrical stimulation of the thalamic nucleus ventralis intermedius (VIM) or the globus pallidus internus (GPi), have been applied for the treatment of movement disorders including tremor or rigidity. 12-15 Studies with PET have shown that electrical stimulations of GPi or VIM change rCBF in various
In another study, high frequency (120 Hz) GPi stimulation consistently increased oxygenated hemoglobin (oxyHb) with a decrease of deoxyHb in an intensity and time dependent manner in a NIRS imaging of the frontal lobe REF .
Changes in cerebral blood oxygenation of the frontal lobe induced by direct electrical stimulation of thalamus and globus pallidus: a near infrared spectroscopy study
Journal of neurology, neurosurgery, and psychiatry
Journal of neurology, neurosurgery, and psychiatry
Medicine