De Novo Aneurysms

De Novo formation means that the patient had a subarachnoid aneurismal hemorrhage (SAH), and was re-admitted later for another aneurysm, which was not visible during the first operation.

The Study of De Novo Aneurysms

The following information was taken from a review article (Tonn et al.,Neuroradiology 41: 674-679, 1999) of all the angiographically proven de novo cases published up to 1999 (50 patients).

The average rate of onset of symptoms of a de novo aneurysm after the first SAH is 9.9 ± 6.7yrs (range 3-34 yrs), however, 44% of these de novo aneurysms become symptomatic 3-6 years after the first SAH. Neither smoking nor patient age affected this interval, however the interval was significantly reduced for patients with a history of hypertension (6.9 ± 5.1 yrs) compared to those without (11.0 ± 3.8 yrs).

This study, in reviewing the literature, found that the likelihood of first-time congenital aneurismal SAH is 3.7-5.7 times higher for smokers. The study did not find a significant difference between ‘usual’ and de novo aneurysm formation among smokers. Smoking was more frequent with both de novo and ‘usual’ aneurysm patients than in the controls without SAH indicating that smoking contributes to both.

The study found rates of hypertension to range 25%-31% for ‘usual’ aneurysms and 67% for de novo suggesting that maintaining a low blood pressure would be useful for patients who have undergone one SAH. Smoking and arterial hypertension appear to be independent risk factors.

There is also a high risk of multiplicity in de novo formation. Most studies of de novo aneurysms show a few common clinical characteristics among patients: a history of smoking, arterial hypertension and youth. Even if these are not the actual cause of aneurysm development, they certainly aggravate the situation and encourage further development.

A certain "at-risk" group for de novo aneurysms emerges from their conclusions: "patients with a history of previous aneurismal SAH, aged 50 years or less, with arterial hypertension and a history of smoking." Apart from monitoring and treating the high blood pressure and hypertension state, the patients should refrain from smoking. They also advise follow-up angiography at an interval of 4-5 years after the initial SAH, 3 years in hypertensive patients. Note: MRA, suggested for patients with carotid ligation, may not show de novo aneurysms within the Circle of Willis.