Correlation between hyperhemoglobinemia and pseudosubarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a severe cerebrovascular condition. Some cases present with typical signs of SAH on head computed tomography (CT), whereas other cases have a condition known as pseudo-SAH, with no bleeding actually present. In our clinical experience, we noted that cases of hyperhemoglobinemia often also had pseudo-SAH. Here we investigated the relationship between hyperhemoglobinemia and pseudo-SAH and explored the underlying mechanism.

We retrospectively collected data for patients who were treated for hyperhemoglobinemia in our hospital and had available brain CT scans. An age-matched control group of patients with normal hemoglobin levels was used to compare the incidence of pseudo-SAH between individuals with elevated versus normal hemoglobin levels. Spearman correlation and logistic regression analyses were performed to identify correlations between pseudo-SAH and hemoglobin level as well as gender, history of chronic obstructive pulmonary disease, and smoking history.

The incidence of pseudo-SAH was significantly higher in hyperhemoglobinemia group than in the control group (12.5% vs. 1.6%, respectively, P < 0.001), and within the hyperhemoglobinemia group, it was significantly higher among those with a hemoglobin value ≥210 g/L than among those with a hemoglobin value <210 g/L (29.2% vs. 8.8%, respectively, P < 0.001). Spearman correlation analysis and logistic regression analysis showed a significant correlation between pseudo-SAH and hyperhemoglobinemia but no significant correlation between pseudo-SAH and gender, COPD, or smoking history.

Hyperhemoglobinemia may be a contributing factor to pseudo-SAH. Clinicians should be aware of this phenomenon and be careful to distinguish pseudo-SAH from SAH, particularly in patients with hyperhemoglobinemia.