Evidence that a panel of neurodegeneration biomarkers predicts vasospasm, infarction, and outcome in aneurysmal subarachnoid hemorrhage

Abstract

Biomarkers for neurodegeneration could be early prognostic measures of brain damage and dysfunction in aneurysmal subarachnoid hemorrhage (aSAH) with clinical and medical applications. Recently, we developed a new panel of neurodegeneration biomarkers, and report here on their relationships with pathophysiological complications and outcomes following severe aSAH. Fourteen patients provided serial cerebrospinal fluid samples for up to 10 days and were evaluated by ultrasonography, angiography, magnetic resonance imaging, and clinical examination. Functional outcomes were assessed at hospital discharge and 6-9 months thereafter. Eight biomarkers for acute brain damage were quantified: calpain-derived α-spectrin N- and C-terminal fragments (CCSntf and CCSctf), hypophosphorylated neurofilament H,14-3-3 β and ζ, ubiquitin C-terminal hydrolase L1, neuron-specific enolase, and S100β. All 8 biomarkers rose up to 100-fold in a subset of patients. Better than any single biomarker, a set of 6 correlated significantly with cerebral vasospasm, brain infarction, and poor outcome. Furthermore, CSF levels of 14-3-3β, CCSntf, and NSE were early predictors of subsequent moderate-to-severe vasospasm. These data provide evidence that a panel of neurodegeneration biomarkers may predict lasting brain dysfunction and the pathophysiological processes that lead to it following aSAH. The panel may be valuable as surrogate endpoints for controlled clinical evaluation of treatment interventions and for guiding aSAH patient care.

Figure 1. CSF changes in 3 neurodegeneration biomarkers after aneurysm rupture.

(A) Western blot analyses of 14-3-3β, a calpain-cleaved α-spectrin COOH-terminal fragment (CCSctf), and UCH-L1 in 3 aSAH cases at the indicated times post-rupture (in days). Case 25 is representative of the subset of aSAH patients exhibiting large elevations in every neurodegeneration biomarker. Case 9, in contrast, shows a delayed increased in neurodegeneration biomarkers starting on day 5 after aneurysm rupture. Case 19 is representative of the subset of aSAH cases exhibiting consistently low or undetectable biomarker levels over the entire 10 day post-rupture period. (B) Western blot analysis of CCSctf levels 5 days post-rupture for 13 aSAH cases. Quantitative analysis (see Methods) showed that CSF levels of this biomarker vary by 100-fold across patients.

Figure 2. Summary of neurodegeneration biomarker increases up to 10 days after severe aSAH.

The figure depicts CSF levels for 8 neurodegeneration biomarkers measured serially in a cohort of 14 severe aSAH cases. The levels of each marker have been divided into 4 categories as described in Methods , representing either low (blue), medium (yellow), high (orange), or very high (red).

Figure 3. Time courses for 6 CSF neurodegeneration biomarkers in relation to functional outcome and the severity of cerebral vasospasm.

Long-term outcome was dichotomized to either poor (closed circles: GOS-E  = 1–4; mRS  = 4–6) or good (open boxes: GOS-E  = 5–8; mRS  = 1–3), while angiographic vasospasm was categorized as either moderate/severe (closed circles) or absent/mild (open boxes) as described in Methods. Mean CSF levels of each neurodegeneration biomarker at the indicated times post-aneurysm rupture (in days) are shown with the standard error of the mean. Statistically significant between-group differences (p<0.05) are identified by asterisk. In cases for which CSF samples were available at both 7 and 10 days post-rupture, the higher marker level was considered.