gms | German Medical Science

Objective: Cerebral infarction in the context of vasospasm after aneurysmal subarachnoid hemorrhage remains a severe and dreaded complication. Therefore, early diagnosis of misery perfusion is crucial. It has already been shown that hypoperfused brain areas can be detected with CT perfusion (CTP) measurements in patients with acute clinical deterioration. The aim of this study was to evaluate if a single CTP at time of neurological deterioration is sufficient or if serial CTP examinations are needed to reliably detect the areas at risk. In addition, the perfusion parameters with the highest specifity and sensitivity were determined.

Methods: A retrospective analysis of all CTP examinations in a group of patients with aneurysmal subarachnoid hemorrhage, which were treated between 2012 and 2015 at the University Hospital Bern, was performed. Patients with CTP within 24 hours after aneurysm treatment (baseline CTP) and follow up CTP in the phase of vasospasm risk – or at point of neurological deterioration – were included. Two groups were divided – patients with deterioration, defined as GCS decrease of ≥ 2 or increase of NIHSS of ≥ 2 later than 5 days after hemorrhage, and patients without acute clinical deterioration. The following CTP parameters were analyzed for predefined brain regions: Mean Transit Time (MTT), Time To Peak (TTP), Time To Drain (TTD), Cerebral Blood Flow (CBF) and Cerebral Blood Volume (CBV). CTP parameter thresholds for (i) changes compared to the baseline examination, (ii) absolute values at the time point of deterioration and (iii) between-hemisphere differences at the time point of deterioration were determined and sensitivities and specifities were calculated.

Results: Fifty-six patients were finally included – 33 with and 23 without neurological deterioration. CTP parameters MTT, TTP and TTD showed the highest sensitivities and specifities for the symptomatic territory in case of acute diagnostic. Threshold values were 4.15 sec for MTT, 10.16 sec for TTP and 4.7 sec for TTD. Similar results were seen for inter-hemispheric comparisons with highest sensitivities and specifities for MTT, TTP and TTD. Comparison of CTP parameters acquired at the time point of clinical deterioration with a baseline examination yielded no additional diagnostic gain. Regarding all categories, TTD was CTP parameter with the highest sensitivity and specifity.

Conclusion: CTP parameters MTT, TTP and TTD offer the highest sensitivities and specifities in the detection of critically perfused brain regions. Based on our data, we conclude that baseline CTP does not provide additional diagnostic information and, therefore, a CTP in acute neurological deterioration is sufficient.