====== Intracranial Aneurysm History ======

The study of [[intracranial aneurysm]]s has grown at an astounding rate since Sir [[Charles Symonds]] association of hemorrhage within the [[subarachnoid space]] to [[intracranial aneurysm]]s in [[1923]].

The need to secure unstable intracranial [[aneurysm]]s was identified by [[Harvey Williams Cushing]] (1923)
((Cushing H. Contributions to study of intracranial aneurysms. Guys Hosp Rep. 1923;73:159–63.))

The first surgical treatment of an intracranial aneurysm with [[wrapping]] was made by [[Norman McOmish Dott]] in [[1931]]
((Zhou J, Agarwal N, Hamilton DK, Koltz MT. The 100 most influential
publications pertaining to intracranial aneurysms and aneurysmal subarachnoid
hemorrhage. J Clin Neurosci. 2017 Aug;42:28-42. doi: 10.1016/j.jocn.2017.02.057. 
Epub 2017 Mar 25. Review. PubMed PMID: 28351533.
))
, but the first modern-era [[clipping]] [[procedure]] was performed by [[Walter Edward Dandy]] in [[1937]]
((Dandy WE. Intracranial aneurysm of the internal carotid artery. Ann Surg. 1938;107:654–9.)).
Since then, the progressive evolution of [[device]]s, particularly the [[operating microscope]], has resulted in [[intracranial]] surgery to secure aneurysms presenting with [[subarachnoid hemorrhage]], or otherwise, becoming routine procedure.

The latest era of aneurysm treatment has seen the meteoric rise and acceptance of [[neuroendovascular treatment]] by interventional radiologists. Endosaccular obliteration by insertion of silver wire was first reported in [[1941]] 
((Werner SC, Blakemore AH, King BG. Aneurysm of the internal carotid artery within the skull: wiring and electrothermic coagulation. JAMA. 1941;116:578–82.)).
During the 1970s and 1980s, the evolution of [[catheter]]s and [[detachable]] devices, most importantly metal [[coil]]s, resulted in the ability to secure [[intracranial aneurysm]]s without the need for operative trauma or [[dissection]] to the brain. However, even the earliest studies of modern [[coiling]] techniques pointed towards some limitations of these techniques and suggested that some [[aneurysm]]s might be more challenging or unsuitable for [[endovascular therapy]] 
((Vinuela F, Duckwiler G, Mawad M. Guglielmi detachable coil embolisation of acute intracranial aneurysm: perioperative anatomical and clinical outcome in 403 patients. J Neurosurg. 1997;86:475–82.))
These difficulties were partially addressed over the 1990s by development of [[balloon assisted coiling]] and [[stent assisted coiling]] techniques.

One of the most impressive studies on the outcomes of the two treatments for [[intracranial aneurysm]]s, the [[International Subarachnoid Aneurysm Trial]] (ISAT) was presented in [[2002]] 
((Molyneux A, Kerr R, Stratton I, et al. International subarachnoid aneurysm trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised trial. Lancet. 2002;360:1267–74.)).
It suggested that the [[ruptured intracranial aneurysm]] treated [[endovascular]]ly had a better one-year outcome, maintained at seven years, in terms of neurodisability and [[seizure]]s. An increased risk of delayed [[rebleeding]] compared with the aneurysm treated surgically was seen. The practice of radiological follow up to identify the possible recurrence was encouraged, and rates of prophylactic retreatment following endovascular therapy were noted to be higher that for open surgery.

In parallel with these developments, advances in both the resolution and availability of neuroimaging modalities have led to an increased number of patients presenting with aneurysms that are considered [[asymptomatic]]. Epidemiological data have become accepted that offer year-on-year risk stratification of the risks of subarachnoid hemorrhage from such aneurysms
((Werner M, van der Schaaf I, Algra A, et al. Risk of rupture of unruptured intracranial aneurysms in relation to patient and aneurysm characteristics: an updated meta-analysis. Stroke. 2007;38:1404–10.)).
The modern neurosurgeon or neurologist is hence routinely asked to consider treatments for the unruptured, asymptomatic aneurysm, in addition to the emergency workload of those presenting with subarachnoid hemorrhage. The patient group over time has become younger, healthier, and better informed prior to presentation. Particularly those patients that present with an unruptured aneurysm after screening following the subarachnoid hemorrhage of a close relative may have strong psychological factors influencing their decisions to have treatment or not. They may be very keen to avoid the need for long-term follow up and eliminate worry. For these patients the issues of retreatment are very serious. For the experienced vascular neurosurgeon the operative conditions in the context of unruptured aneurysms are ideal and operative morbidities should be minimal. These factors, coupled with the recognition of the key differences not only in presentation but also in treatment goal, often combine to make surgical treatment of the unruptured aneurysm a preferable option
((Heros RC. Clip ligation or coil occlusion? J Neurosurg. 2006;104:341–3.)).

Previous data from previous studies such as ISAT is difficult to apply to newer cohorts of patients. We now see a different patient group requiring aneurysm surgery. They have progressed from those presenting acutely in various states of disability, to a group that includes fewer such patients, but a greater proportion of recurrent or residual aneurysms post-coiling, and the unruptured group requiring treatment with the highest definitive success rate. Only further longitudinal studies of these newer groups of patients will guide us in time as to the precise outcomes
((Crocker M, Tolias C. What future for vascular neurosurgery? Vasc Health Risk
Manag. 2007;3(3):243-4. PubMed PMID: 17703631; PubMed Central PMCID: PMC2293965.
)).

===== References =====