Hirotsugu Yukawa

Transcranial Regional Cerebral Oxygen Saturation Monitoring during Carotid Endarterectomy as a Predictor of Postoperative Hyperperfusion

OBJECTIVEHyperperfusion syndrome is a rare but potentially devastating complication that can occur after carotid endarterectomy (CEA). The purpose of this study was to determine whether intraoperative transcranial regional cerebral oxygen saturation (rSO2) monitoring via near-infrared spectroscopy could be reliably used to identify patients at risk for post-CEA hyperperfusion. METHODSrSO2 was intraoperatively monitored for 50 patients undergoing CEA for treatment of ipsilateral internal carotid artery stenosis (≥70%). Cerebral blood flow (CBF) was also assessed, with single-photon emission computed tomography, before and immediately after CEA. RESULTSPost-CEA hyperperfusion (CBF increase of ≥100%, compared with preoperative values) was observed for six patients. A significant linear correlation was observed between the rSO2 increases immediately after declamping of the internal carotid artery and the CBF increases immediately after CEA (r2 = 0.247, P = 0.0002). The sensitivity and specificity of the rSO2 increases for detection of post-CEA hyperperfusion were 100 and 86.4%, respectively, with a cutoff point of 5%. A strong linear correlation was observed between the rSO2 increases at the end of the procedure and the CBF increases immediately after CEA (r2 = 0.822, P < 0.0001). Both the sensitivity and the specificity of the rSO2 increases for detection of post-CEA hyperperfusion were 100% with a cutoff point of 10%. Hyperperfusion syndrome developed for one patient with post-CEA hyperperfusion, but intracerebral hemorrhage did not occur. CONCLUSIONIntraoperative rSO2 monitoring can reliably identify patients at risk for hyperperfusion after CEA.

Brain temperature and cerebral blood flow imaging in patients with severe subarachnoid hemorrhage: report of two cases

BACKGROUND Temperature reversal, which is defined as observation of higher brain temperature than systemic temperature followed by lower brain temperature than systemic temperature, implies a poor prognosis in patients with severe subarachnoid hemorrhage (SAH). Serial regional cerebral blood flow (CBF) imaging using single-photon emission tomography (SPECT) was performed in 2 patients with severe SAH who showed temperature reversal. CASE DESCRIPTION 54-year-old woman and a 55-year-old man with severe SAH underwent ventricular drainage using a catheter that allowed monitoring of the brain temperature. SPECT imaging in these two patients showed that CBF was preserved before the occurrence of the temperature reversal and was exhausted afterwards. These patients died within 2 to 3 days. CONCLUSIONS Temperature reversal may indicate the exact time when absence of brain perfusion occurs, causing irreversible brain damage.

Very early and standard Tc-99m ethyl cysteinate dimer SPECT imaging in a patient with reperfusion hyperemia after acute cerebral embolism.

&NA; It has been reported that Tc‐99m ethyl cysteinate dimer (ECD) SPECT imaging may not show reperfusion hyperemia in patients with subacute stroke. The authors describe a patient with embolic middle cerebral artery occlusion who was examined using xenon‐133 and dynamic and standard Tc‐99m ECD SPECT immediately after early recanalization. Standard Tc‐99m ECD SPECT images revealed hypoactivity in the ipsilateral middle cerebral artery territory. In contrast, the dynamic Tc‐99m ECD SPECT images from the first scan (very early images acquired 36 seconds after injection) showed hyperactivity in the same region and provided imaging contrast comparable to what would be obtained with xenon‐133 tomography. Hemorrhagic transformation later developed in this region. These results indicate that images from very early dynamic Tc‐99m ECD SPECT of areas with irreversible changes produced by acute stroke can reveal reflow hyperemia that standard Tc‐99m ECD SPECT images fail to show.

Atypical finding of brain Tc-99m-ECD SPECT imaging in herpes simplex encephalitis.

Lesions in acute herpes simplex encephalitis (HSE) have been reported to show decreased uptake of Tc-99m ethyl cysteinate dimer (ECD). A patient with acute HSE displaying a lesion in the left temporal lobe was evaluated by means of Tc-99m ECD single-photon emission computed tomography (SPECT). Dynamic SPECT images indicated regionally increased uptake of tracer in the ipsilateral temporal lobe in early phases, followed by slight washout of Tc-99m ECD from the lesion. Static SPECT images revealed increased tracer uptake in the same region. MRI later demonstrated that the HSE lesion involved the whole cortex of the temporal lobe on the affected side. These findings suggest that acute HSE lesions do not always exhibit hypoactivity on static Tc-99m ECD SPECT, and that dynamic Tc-99m ECD SPECT may help physicians diagnose acute HSE.