In this study, we demonstrated an inverse relationship between CTACFS and total infarct volume. This correlation suggests that CTACFS is a reliable parameter to predict final outcome of acute stroke. A good initial CTACFS has a protective effect which results in a smaller total infarct size.

We also demonstrated an inverse relationship between CTACFS and NIHSS at initial presentation. Those patients with a larger supply of collaterals had less clinical impairment at presentation which again suggests a protective effect.

Those patients with relatively good collaterals and yet with substantial clinical impairment at presentation seems to benefit more from intervention with mechanical thrombectomy and/or thrombolysis. Unfortunately, this finding was not able to be demonstrated as statistically significant in the current study. A larger patient population in this category is needed to confirm this finding.

Limitations

There are several limitations to this study. First, we did not evaluate NIHSS at presentation and at discharge for all patients as our institution just recently began this documentation for all stroke patients. This resulted in a low number of patients included in the evaluation of the effectiveness of treatment in those patients with a large number of collaterals but yet with a significant stroke deficit. Second, no long term patient follow-up was obtained such as with the modified Rankin Scale (mRS). A prospective study could assist in eliminating the limitations of gathering NIHSS and mRS. Third, our patient population was limited to those patients designated as Stroke Alerts or Stroke Codes at our institution.

Despite these limitations, our results show a significant benefit of a good collateral supply with a more favorable outcome. Previous studies have demonstrated the benefit of leptomeningeal collaterals [1,5]. Our results provide supporting evidence for these prior studies. However, to our knowledge this is the first study to raise the possibility that a subgroup of patients with a relatively mismatch of relatively good collateral score and higher stroke deficits may benefit more from intervention.