Clinical and radiological heterogeneity in aneurysmal sub-arachnoid haemorrhage according to risk-factor profile

Risk factors for aneurysmal sub-arachnoid haemorrhage can be divided into environmental and inherited factors; the latter being presumed more important in young patients. We explored in young sub-arachnoid haemorrhage patients whether risk-factor profiles influence clinical and radiological characteristics of aneurysms and sub-arachnoid haemorrhage.

From the 2139 aneurysmal sub-arachnoid haemorrhage patients who had been entered in our prospectively collected database between January 1997 and August 2012, we retrieved data on young (18-40 years) aneurysmal sub-arachnoid haemorrhage patients and compared those with smoking or hypertension (atherogenic risk factors) with those without. Clinical and radiological characteristics were compared with risk ratios and corresponding 95% confidence intervals. Possible confounding by age and gender was adjusted with multivariable Poisson regression analysis.

Patients with atherogenic risk factors (n = 113) were less often female (risk ratio: 0·7; 95% confidence interval: 0·6↔0·9), had less often a small aneurysm (risk ratio: 0·4; 95% confidence interval: 0·2↔0·7), and tended to have less often middle cerebral artery aneurysms (risk ratio: 0·5; 95% confidence interval: 0·3↔1·1) than the 29 patients without these risk factors. After adjustment for gender and age, patients with atherogenic risk factors had more often multiple aneurysms (risk ratio: 7·5; 95% confidence interval: 1·1↔52·9). There were no overt differences in the amount of cisternal and intraventricular blood, the shape of the aneurysm, and configuration of the circle of Willis between the patient groups. After adjustment for gender and age, patients with atherogenic risk factors had more often poor outcome (risk ratio: 3·8; 95% confidence interval: 1·0↔14·5).

Young sub-arachnoid haemorrhage patients without atherogenic risk factors are rare. Clinical and radiological characteristics vary between sub-arachnoid haemorrhage patients with different risk-factor profiles. This clinical heterogeneity should be taken into account in future genetic and other etiological studies.