Psychosomatic symptoms during South East Asian haze crisis are related to changes in cerebral hemodynamics

OBJECTIVES

Forest fires in South Asia lead to widespread haze, where many healthy individuals develop psychosomatic symptoms. We investigated the effects of haze exposure on cerebral hemodynamics and new symptoms. We hypothesised that vasoactive substances present in the haze, would lead to vasodilation of cerebral vasculature, thereby altering cerebral hemodynamics, which in turn may account for new psychosomatic symptoms.

METHODS

Seventy-four healthy volunteers were recruited, and serial transcranial Doppler (TCD) ultrasonography was performed to record blood flow parameters of bilateral middle cerebral arteries (MCA). The first TCD was performed in an air-conditioned environment. It was repeated outdoors after the participants spent 30-minutes in the haze environment. The prevailing level of pollutant standards index (PSI) was recorded. Appropriate statistical analyses were performed to compare cerebral hemodynamics at baseline and after haze exposure in all participants. Subgroup analyses were then employed to compare the findings between symptomatic and asymptomatic participants.

RESULTS

Study participants' median age was 30 years (IQR 26-34), and new psychosomatic symptoms were reported by 35 (47.3%). There was a modest but significant decrease in pulsatility index (PI) and resistivity index (RI) in the left MCA after haze exposure (PI: p = 0.026; RI: p = 0.021). When compared to baseline parameters, haze exposure resulted in significantly lower mean PI (p = 0.001) and RI (p = 0.001) in symptomatic patients, but this difference was not present in asymptomatic patients (PI: p = 0.919; RI: p = 0.970).

CONCLUSION

Haze causes significant alterations in cerebral hemodynamics in susceptible individuals, probably responsible for various psychosomatic symptoms. The prognostic implications and health effects of haze require evaluation in a larger study.

Rationale and design of a randomized trial of early intensive blood pressure lowering on cerebral perfusion parameters in thrombolysed acute ischemic stroke patients

BACKGROUND AND RATIONALE

Uncertainty persists over the optimal management of blood pressure (BP) in the early phase of acute ischemic stroke (AIS). This study aims to determine the safety and effects of intensive BP lowering on cerebral blood flow (CBF) and functional in AIS patients treated with intravenous thrombolysis.

METHODS

In a randomized controlled trial, 54 thrombolysed AIS patients with a systolic BP of 160 to 180 mm Hg will be randomized to early intensive BP lowering (systolic target range 140-160 mm Hg) or guideline-based BP management (systolic range 160-180 mm Hg) during first 72-hours using primarily intravenous labetalol. We hypothesize that early intensive BP lowering will not reduce CBF by 20% and/or increase the volume of hypoperfused tissue by >20% on computed tomographic perfusion. Clinical outcome will be assessed using a dichotomized modified Rankin scale (scores 0-1 as excellent outcome vs scores 2-6 as dead or dependent) at 90 days. Other outcome would be symptomatic intracerebral hemorrhage. The trial is registered at ClinicalTrials.gov, NCT03443596.

CONCLUSION

This randomized study will provide important information about the physiological effects of BP reduction on cerebral perfusion after intravenous thrombolysis in AIS.

Abstract TP340: Imaging Related Radiation Dose and Cancer Risk Assessment of Brain in Acute Ischemic Stroke Patients

Background and aims: Recently, safety concerns were raised about the radiation dose for acute ischemic stroke (AIS) patients undergoing computed tomography (CT), CT angiography (CTA) and CT perfusion (CTP). We evaluated precise radiation dose to the brain during various imaging studies in our AIS patients.

Methods: Brain imaging was performed with 64-detector row CT scanner (Phillips-iCT256) using standard protocols recommended by American Association of Physicist in Medicine. For each procedure, volume weighted CT dose index (CTDIvol, mGy) and dose-length product DLP (mGy.cm) were obtained from dose reports generated at the time of acquisition. Organ specific dose to brain, eye, bone marrow and thyroid were also obtained. The estimates of cancer risk were interpolated.

Results: In this prospective study, a total of 18 patients who underwent CT, CTA as well as CTP were included. Mean DLP for non-enhanced CT, CTA and CTP were 1068.25, 1150 and 1197 mGy.cm, respectively. Corresponding whole body effective dose for the CT, CTA and CTP were calculated as 2.57, 2.6, 2.4 mSv, respectively. Cumulative doses to the brain, eyes, bone marrow and thyroid gland were 33.81, 32.8, 1.21 and 1.31 mGy for the non-contrast brain CT. CTDIvol measurements for different protocols tested by the phantom were in agreement with values given in dose reports.

Conclusions: The effective radiation doses are less than previously reported and much below the radiation threshold level for deterministic effects for brain and optic lens (500-2000mGy). Estimated life-time attributable cancer risks are very low with the current radiation doses.

Abstract WP125: Plaque Inflammation Imaging in Carotid Stenosis and Recurrent Cerebral Ischemia

Background and aims: Symptomatic carotid stenosis is associated with an increased risk of early stroke recurrence. Currently, therapeutic decisions are largely based on the luminal narrowing, which mainly explain the cerebral ischemia related to regional hypoperfusion. Plaque inflammation, the initiating event for plaque rupture and thromboembolism (artery-to-artery embolism), is not evaluated routinely in patients with carotid stenosis. Using combined 18F-fluorodeoxyglucose positron-emission tomography (FDG-PET)/computed tomography (CT), we investigated the role of plaque inflammation and stroke recurrence in our cohort of stroke patients with recently symptomatic carotid stenosis.

Methods: This ongoing prospective study aims to include consecutive patients within 30-days of recent stroke and ipsilateral carotid stenosis (≥50%). FDG uptake is quantified as mean standardized uptake values (SUV, g/ml). Patients are followed prospectively for stroke recurrence. Embolic potential of the carotid plaque is estimated by presence of spontaneous microembolic signals (MES) on continuous transcranial Doppler monitoring of the middle cerebral arteries (MCA) for 40 minutes.

Results: Of the 22 patients included in the study, 5 suffered from recurrent cerebral ischemic event in the same vascular territory within 90 days. In patients with recurrent cerebral ischemia, the mean SUV value in the carotid plaque on the side of symptomatic carotid stenosis was higher (3.46g/ml) as compared to the patients without stroke recurrence (1.72g/ml; p=0.03). MES were noted in 3/5 cases with recurrent cerebral ischemia as compared to 2/17 cases (p=0.001)

Conclusions: FDG-PET/CT aids in the imaging of plaque inflammation and identification of patients with higher risk of subsequent cerebral ischemic events. This ongoing study intends to develop a robust prediction model for risk stratification based on luminal stenosis and plaque characteristics for better therapeutic decision-making.

Abstract 220: Neurovascular Uncoupling in Acute Ischemic Stroke Correlates Well With Clinical Fluctuations in Acute Ischemic Stroke

Background and aims: Fluctuations in neurological status are frequently seen during first few days in thrombolysed acute ischemic stroke (AIS) patients. Underlying mechanisms for these fluctuations often remain unclear. Cerebral homeostatic balance is regulated by autoregulation and neurovascular coupling (NVC). We hypothesized that neurovascular uncoupling in AIS contributes to the fluctuations in neurological status.

Methods: In this ongoing prospective study, consecutive and thrombolyzed AIS patients were recruited within 12 hours of symptom-onset. Serial CT perfusion (CTP) imaging (within 12 hours, at 24 and 72 hours after symptom-onset) were performed. Serial Quantitative EEG (QEEG) were performed, close to CTP imaging. Power within the alpha band (8-15Hz) was determined in each channel using epochs of 10-seconds % calculated for each hemisphere. Continuous transcranial Doppler (TCD) recording were obtained from both middle cerebral arteries, simultaneously with EEG. Neurological status was monitored with serial NIH stroke scale (NIHSS) scores. Neurovascular uncoupling was defined as a mismatch among CTP, QEEG and clinical findings. QEEG, CTP and TCD data were analysed independently by investigators blinded to the clinical findings.

Results: A total of 32 patients (19 male, median age 68 years (range 56-86) were included. Median NIHSS score at recruitment was 8 points (range 1-24). NIHSS fluctuations by 4 or more points (deterioration followed by improvement or deterioration following improvement in absence of re-occlusion) were noted in 13 (40%) cases. Increasing cerebral edema (2 cases) and regional hyperperfusion (4 cases) were seen on serial CTP. Remaining 7 cases showed serial improvement in CTP. QEEG showed significantly increased inter-hemispheric alpha band power ratio (unaffected hemisphere/affected hemisphere ratio more than 1.5), irrespective of the CTP and TCD results, suggestive of neurovascular uncoupling as the underlying mechanism for early neurological fluctuations.

Conclusion: Neurovascular uncoupling is a relatively frequent phenomenon during first few days of acute ischemic stroke. Multi-modal monitoring is useful in identifying these patients for appropriate therapeutic decision making.