Current advances in the diagnosis of vasospasm

Non-invasive assessment of vasospasm following aneurysmal SAH using C-arm FDCT parenchymal blood volume measurement in the neuro-interventional suite: Technical feasibility

INTRODUCTION

Cerebral vasospasm is the leading cause of morbidity and mortality in patients with aneurysmal subarachnoid haemorrhage (SAH) surviving the initial ictus. Commonly used techniques for vasospasm assessment are digital subtraction angiography and transcranial Doppler sonography. These techniques can reliably identify only the major vessel spasm and fail to estimate its haemodynamic significance. To overcome these issues and to enable comprehensive non-invasive assessment of vasospasm inside the interventional suite, a novel protocol involving measurement of parenchymal blood volume (PBV) using C-arm flat detector computed tomography (FDCT) was implemented.

MATERIALS AND METHODS

Patients from the neuro-intensive treatment unit (ITU) with suspected vasospasm following aneurysmal SAH were scanned with a biplane C-arm angiography system using an intravenous contrast injection protocol. The PBV maps were generated using prototype software. Contemporaneous clinically indicated MR scan including the diffusion- and perfusion-weighted sequences was performed. C-arm PBV maps were compared against the MR perfusion maps.

RESULTS

Distribution of haemodynamic impairment on C-arm PBV maps closely matched the pattern of abnormality on MR perfusion maps. On visual comparison between the two techniques, the extent of abnormality indicated PBV to be both cerebral blood flow and cerebral blood volume weighted.

CONCLUSION

C-arm FDCT PBV measurements allow an objective assessment of the severity and localisation of cerebral hypoperfusion resulting from vasospasm. The technique has proved feasible and useful in very sick patients after aneurysmal SAH. The promise shown in this early study indicates that it deserves further evaluation both for post-SAH vasospasm and in other relevant clinical settings.

Correlation of transcranial color Doppler to n20 somatosensory evoked potential detects ischemic penumbra in subarachnoid hemorrhage

Background:

Normal subjects present interhemispheric symmetry of middle cerebral artery (MCA) mean flow velocity and N20 cortical somatosensory evoked potential (SSEP). Subarachnoid haemorrhage (SAH) can modify this pattern, since high regional brain vascular resistances increase blood flow velocity, and impaired regional brain perfusion reduces N20 amplitude. The aim of the study is to investigate the variability of MCA resistances and N20 amplitude between hemispheres in SAH.

Methods:

Measurements of MCA blood flow velocity (vMCA) by transcranial color-Doppler and median nerve SSEP were bilaterally performed in sixteen patients. MCA vascular changes on the compromised hemisphere were calculated as a ratio of the reciprocal of mean flow velocity (1/vMCA) to contralateral value and correlated to the simultaneous variations of interhemispheric ratio of N20 amplitude, within each subject. Data were analysed with respect to neuroimaging of MCA supplied areas.

Results:

Both interhemispheric ratios of 1/vMCA and N20 amplitude were detected >0.65 (p <0,01) in patients without neuroimages of injury. Both ratios became <0.65 (p <0.01) when patients showed unilateral images of ischemic penumbra and returned >0.65 if penumbra disappeared. The two ratios no longer correlated after structural lesion developed, as N20 detected in the damaged side remained pathological (ratio <0.65), whereas 1/vMCA reverted to symmetric interhemispheric state (ratio >0.65), suggesting a luxury perfusion.

Conclusion:

Variations of interhemispheric ratios of MCA resistance and cortical N20 amplitude correlate closely in SAH and allow identification of the reversible ischemic penumbra threshold, when both ratios become <0.65. The correlation is lost when structural damage develops.

Predictors analysis of symptomatic cerebral vasospasm after subarachnoid hemorrhage

PURPOSE

symptomatic cerebral vasospasm (SCVS) is still lacking in reliable early warning methods and often diagnosed after clinical deterioration of neurological function, making prevention and treatment extremely passive. This study investigates the risk factors relevant to SCVS after subarachnoid hemorrhage (SAH) in order to provide useful information for clinical work.

MATERIALS AND METHODS

clinical data of 211 patients with SAH was reviewed in this study. 16 risk factors relevant to SCVS were retrospectively analyzed, including univariate analysis and logistic analysis.

RESULTS

of 211 patients, 81 were found to have SCVS (38.4%). Univariate analysis showed that age, history of hypertension, Hunt-Hess grade at admission, modified Fisher grade, aneurysm location, fever and intraventricular blood clot reached statistical significance (P < 0.05), suggesting that they might be risk factors to SCVS. However, logistic analysis showed that only age (OR=1.027, 95% CI=1.002-1.053, P < 0.05) and modified Fisher grade (OR=2.985, 95% CI=2.048-4.352, P < 0.05) entered the regression equation, suggesting both were independent risk factors.

CONCLUSIONS

SCVS is the final result of multiple factors acting together. Age and modified Fisher grades are independent risk factors to SCVS.

Accuracy of transcranial Doppler ultrasonography and single-photon emission computed tomography in the diagnosis of angiographically demonstrated cerebral vasospasm

Object

The goal of this study was to assess the accuracy of the routine clinical use of transcranial Doppler (TCD) ultrasonography and SPECT in predicting angiographically demonstrated vasospasm.

Methods

Following receipt of institutional review board approval, the authors reviewed the records of patients with subarachnoid hemorrhage who had been admitted between 2004 and 2005 and underwent TCD ultrasonography and SPECT evaluations within 24 hours of cerebral angiography. Patients were categorized based on the presence or absence of vasospasm and/or hypoperfusion in the anterior cerebral arteries (ACAs), middle cerebral arteries (MCAs), and basilar arteries (BAs) or posterior cerebral arteries (PCAs) according to each imaging modality. Logistic regression was used to estimate the odds ratio (OR) of an angiographically demonstrated vasospasm also detected on TCD ultrasonography and SPECT.

Results

One hundred fifty-two patients (101 women) with a mean age (± standard deviation) of 53 ± 13 years were included in the study. In the ACA, the OR of a vasospasm on TCD ultrasonography was 27 (95% confidence interval [CI] 3–243) and on SPECT 0.97 (95% CI 0.36–2.6); in the MCA, 17 (95% CI 5.4–55) and 2.0 (95% CI 0.71–5.5), respectively; in the BA, 4.4 (95% CI 0.72–27) and 5.6 (95% CI 0.89–36), respectively. There was no substantial change in the relative odds of a vasospasm when the findings on TCD ultrasonography and SPECT were considered jointly.

Conclusions

Transcranial Doppler ultrasonography appears to be highly predictive of an angiographically demonstrated vasospasm in the MCA and ACA; however, its diagnostic accuracy was lower with regard to vasospasm in the BA. Single-photon emission computed tomography was not predictive of a vasospasm in any of the vascular territories assessed.

[Aneurysmal subarachnoid hemorrhage. Significance and complications]

Despite substantial improvement in the management of patients with aneurysmal subarachnoid hemorrhage (SAH), including early aneurysm occlusion by endovascular techniques and surgical procedures, a significant percentage of patients with SAH still experience serious sequelae of neurological or cognitive deficits as a result of primary hemorrhage and/or secondary brain damage. Available neuromonitoring methods for early recognition of ischemia include, among others, measurement of brain tissue O(2) partial pressure, brain metabolism with microdialysis and monitoring of regional blood flow. The triple-H therapy (arterial hypertension, hypervolemia and hemodilution) is the treatment of choice of a symptomatic vasospasm and leads to an enduring recession of ischemic symptoms, if initiated early after the onset of a vasospasm-linked ischemic neurological deficit. Further promising therapy approaches are the administration of highly selective ET(A) receptor antagonists and intracisternal administration of vasodilators in depot form. This review summarizes the major neurological and non-neurological complications following aneurysm occlusion. Possible neuromonitoring techniques to improve diagnosis and therapy for treatment of symptomatic vasospasm as well as extracranial complications are discussed.