Tapan Mehta, MBBS, MPH

Korja M, Kivisaari R, Rezai Jahromi B, Lehto H. Natural History of Ruptured but Untreated Intracranial Aneurysms. Stroke. 2017

Over the past fifty years, understanding of the natural course of aneurysmal subarachnoid hemorrhage (aSAH) has concurrently transformed the standard management approaches. With the awareness of risk related to aneurysm re-rupture (about 15% within few hours and overall cumulative risk of 40%–50% at 6 months) among patients who survive the initial event, securing the aneurysm as soon as possible has become the standard of care. Korja et al present an interesting retrospective observational study that depicts the natural course of untreated ruptured intracranial aneurysms.

Previously, Pakarinen et al (1967) investigated 589 patients who had intracranial primary SAH (aneurysmal and other causes) during the period of 1954 to 1961. Korja et al studies mortality and morbidity amongst 510 aSAH patients admitted at the same hospital center from 1967 to 2007, who did not receive any treatment in terms of securing the ruptured aneurysm. The diagnosis of intracranial aneurysm was confirmed with cranial CT-angiography or conventional angiography, and the diagnosis of SAH was confirmed with lumbar puncture or cranial CT scan. All the patients included in the study were followed until death.

The authors have investigated age, admission delays, mortality and survival from symptom onset, by classifying the study cohort into quartiles based on time. It is important to note that 50% of the study population is from the first 10 years of the study period (1968 to 1978). Higher mortality, increasing proportion of poor grade SAH at presentation, lower median survival time, and lower admission delay from symptom onset (Table 1, below), when compared with an increasing number of quartile, depict the change in rationale for who would not get treatment in terms of securing the aneurysm over the past fifty-year period. Although the study is not designed to address the increase in mean and median age with increasing quartile number, it is an interesting finding, and the difference in risk factor modification and screening over the period of time could be a contributor to this finding. Natural history of untreated aSAH based on onset of symptoms stratified by admission delays is reflected in Table 2 (below).

Table 1. Age, Admission Delays, and Survival From Symptom Onset

Table 2. Mortality From Onset of Symptoms Stratified by Admission Delays

The most common reasons for conservative treatment were poor grade during initial presentation (40%) followed by anticipated perioperative challenges (19%) and death before planned treatment (16%). These numbers do not necessarily reflect current practice standards. Advancement in neurosurgical techniques, endovascular techniques for securing the aneurysms and managing delayed cerebral ischemia, and neurocritical care have effectively contributed to a reduced case fatality rate (by 17%) between 1973 and 2002. Overall, this article provides important information on how the aSAH care has evolved in past fifty years, in addition to the understanding of the natural history of untreated aSAH, that could be valuable in modelling resource allocation strategies and further research related to aSAH.