Changes in cerebral blood oxygenation of the frontal lobe inducedby direct electrical stimulation of thalamus and globus pallidus: anear infrared spectroscopy study

摘要

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 Hbwith a decrease of deoxy-Hb in an intensity and time dependent manner.Oxy-Hb and total Hb increased immediately after the onset ofstimulation and then gradually decreased when stimulation wascontinued. By contrast, high frequency (120 Hz) VIM stimulationdecreased oxy-Hb, deoxy Hb and total Hb in an intensity dependentmanner. In the severe tremor patient with VIM stimulation, frequencyresponse was examined by decreasing stimulus frequencies; deoxy-Hbincreased at high frequencies (70-40 Hz), and then decreased below thecontrol level at low frequencies (30-0 Hz), whereas oxy-Hb and totalHb increased consistently at high and low frequencies.
CONCLUSION—Theelectrical stimulation of GPi and VIM caused various CBO changes in thefrontal lobe, which were similar to those found during cognitive tasks.Such a multiplicity of CBO changes in the frontal lobe may be caused bycomplex neuronal circuits in the frontal lobe which has many neuronalconnections to other cortical areas or the basal ganglia.