Intracranial aneurysms (AN) are the most common cause of spontaneous subarachnoid hemorrhage (SAH).
SAH is the most common cause of spontaneous subarachnoid hemorrhage (SAH) and has a high mortality and disability rate. The treatment of AN is becoming more and more advanced, from invasive surgery to minimally invasive neurointerventional endovascular embolization. The development, advantages and applications of the treatment methods are presented in the literature at home and abroad.
1 Non-surgical treatment Xiong Hui, Department of Neurosurgery, Affiliated Hospital of Shandong University of Traditional Chinese Medicine
1.1 The purpose is to prevent re-rupture and bleeding of AN and to control arterial spasm.
1.2 Indications ①Patients are not suitable or their general condition cannot tolerate craniotomy; ②The diagnosis is unknown and further examination is needed; ③Patients refuse surgery or surgery fails; ④As an adjuvant treatment before and after surgery.
1.3 Main measures: ① stay in bed for more than 4 weeks during the acute period, avoid emotional excitement or excessive force; ② hemostatic agents: commonly used are 6-aminohexanoic acid, anti-fibrinolytic aromatic acid, etc.; ③ reduce intracranial pressure: commonly used are mannitol, glycerol fructose, etc.; mannitol can not only reduce intracranial pressure, increase cerebral blood flow, delay blood-brain barrier damage and reduce cerebral edema, but also increase the time of temporary blockage of cerebral arteries during surgery; if necessary If necessary, extraventricular drainage is feasible to drain the cerebrospinal fluid and lower the intracranial pressure; ④ control blood pressure: it is an important measure to prevent and reduce rebleeding, but it should not be lowered too much, because if the increased intracranial pressure is accompanied by arterial twins, the cerebral blood supply will be reduced accordingly, and if the blood pressure is lowered too much, the cerebral perfusion will be insufficient. (6) pay attention to nutrition and water-electrolyte balance; (7) prevent complications such as decubitus ulcers, pneumonia, urinary tract infections, etc.
1
Surgical treatment
The purpose of surgery is to prevent re-rupture and bleeding of AN and to keep the tumor-carrying artery open. Surgical methods are: ① craniotomy: including AN neck clamping or ligation, tumor-carrying artery clamping and AN isolation, AN wrapping, craniotomy AN embolization, AN tumor wall reinforcement, etc.; ② percutaneous puncture embolization AN; ③ extracranial ligation artery. At present, the most common and effective methods are AN neck clamping and endovascular embolization. As for the ligation of extracranial arteries to reduce the blood supply of AN, it is only an indirect surgical method. With the development of micro-neurosurgical techniques, most ANs can be surgically and intuitively clamped. Some scholars believe that microsurgery is currently the preferred treatment method, but for some special areas of AN, exposure is difficult and risky. Some scholars also believe that for grade I, II and grade III patients without obvious impairment of consciousness, surgery should be performed as early as possible to minimize the risk of rebleeding, and also to remove the hematoma before vasospasm and cerebral edema occur and prevent delayed brain damage. In this paper, we focus on AN neck clamping and endovascular embolization.
2.2
AN cervical clamping
2.2.1 Indications ① AN in the anterior part of Willis ring (including ANPCOA–A, AcA-A, McA-A in the superior segment of the internal carotid bed); ② those with mild disease after SAH (Hunt-Hess grade I-III); ③ those with wide tumor neck and important branches from the tumor neck.
2.2.2 Surgical approach Most scholars believe that the Yasargil-s wing point approach as the classical approach can be suitable for AN in various parts of the anterior part of the ring of Willis, and the good and bad exposure of AN can be accomplished by changing the direction of incision forward or backward according to different parts. The carotid pool, optic cross pool, and lateral fissure pool were dissected fully to release cerebrospinal fluid and lower the cerebral pressure, and then the frontal and major lobes were retracted. Medially, the AcoA, At, A2, Heubel-return artery complex on both sides can be clearly revealed by dissecting the endplate pool and removing a small piece of brain tissue at the inferior end of the rectus gyrus; laterally, the PcoA and the beginning of AchA can be clearly revealed at the ICA; posteriorly, the ICA bifurcation can be revealed, and along the MCA-MI, the M2 bifurcation can be dissected, and the ipsilateral superior segment of the bed of the ICA, the MCA-M2 and the AcoA can be revealed through the pterygoid point. The MCA-M2 and the AcoA are well developed. However, the cervical approach has also been used for the internal posterior carotid and middle cerebral AN; the inferior frontal or coronal interhemispheric approach has been used for the anterior AN; for the AN at the bifurcation of the basilar artery, Yasargil reported that the pterygopoint approach was used to complete the procedure through the optic nerve and the internal carotid artery space, while the inferior frontal transcerebellar approach has also been used; the suboccipital approach can be used for the contralateral AN; for the anterior part of the ring of Willis The microsurgical anatomical study was performed on 16 adult cadaveric heads, and the four AN sites in the anterior part of Willis ring, namely the ophthalmic artery (Opit-A), the P-comA-ICA bifurcation and the beginning of the McA-M2 bifurcation, were revealed by using a trans-lateral pterygoid point approach. The success rates were 62%, 50%, 100%, and 62%, respectively.
2.2.3 Surgical methods The most common and effective method is to use microscopic techniques to isolate the AN neck and surrounding vessels for tumor neck clamping surgery. For large tumors with occupying effect, the tumor body can be excised and the stump electrocoagulated, taking care not to injure the penetrating vessels near the tumor body; for small tumors, the stump can be electrocoagulated to make it smaller. For the huge AN which is difficult to reveal the tumor neck clearly, wrapping surgery can be used, and muscle piece, fascia, cotton fiber, gelatin sponge and bio-gel can be used to reinforce the tumor wall; for the shuttle-shaped or difficult to expose AN, isolation surgery and filling surgery can be used.
2.2.4 Timing of surgery The timing of surgery used to be divided into “early” and “delayed or spike period”. The former refers to surgery within 3 d after the onset of SAH, while the latter refers to more than lO d after the onset. In the past, only one-sided emphasis was placed on the less risk of postponed surgery, so surgery was mostly postponed, but disability and death due to rebleeding, vasospasm and cerebral edema were neglected in the waiting period. Most scholars now believe that the efficacy of early surgery is significantly better than postponed surgery because: (1) early cerebral edema is light and the surgery is easy to operate; (2) the blood accumulated in the cerebral pool is cleared during surgery and the subarachnoid cavity is opened at the same time, so that the blood in the subarachnoid cavity is easily drained and the incidence of vasospasm is reduced; (3) the possibility of rebleeding is prevented; (4) the complications caused by excessive use of drugs are prevented; (5) the patient’s psychological tension due to waiting is reduced; and (6) the psychological stress caused by waiting is shortened. (5) reduce the psychological tension of patients due to waiting; (6) shorten the hospitalization days and reduce medical costs; and avoid the possibility of embolic agents entering the AN cavity. For patients with W or V grade, elderly people, or those with other important organ dysfunction or vascular healing period (4-12 d after bleeding), drug treatment is usually chosen, and surgery is performed after the transition to stable period.
2.3 Endovascular embolization
2.3.1 Indications: ①Surgical failure or inaccessible site, such as AN of vertebral basilar artery system; ②Patients with severe disease after SAH (Hunt-Hess grade IV-V); ③Patients with wide spindle shape or base and lack of clearly identifiable tumor neck; ④Patients whose general and local conditions are not suitable for craniotomy and who cannot tolerate general anesthesia.
2.3.2 Purpose
The technology of intravascular embolization is becoming more and more mature. Some studies have shown that its safety and overall efficacy have reached or even surpassed that of traditional craniotomy. While traditional craniotomy is often not tolerated by critically ill patients in the acute phase and some die while waiting for surgery, endovascular embolization is aimed at reducing, modifying, or eliminating the hemodynamic changes within the AN and the local aneurysmal artery, and terminating the AN behavior (the tendency of AN growth, thrombosis, and/or rupture). Endovascular embolization can be performed in the acute phase without re-rupture and bleeding due to wall pressure changes in the AN, whether it is occlusion of the aneurysmal artery or microspring coil embolization.
2.3.3 Embolization materials ① Removable balloon: In 1973, Serbinenlto, a former Soviet scholar, was the first to apply removable balloon for intravascular embolization treatment, initially to occlude the aneurysm-carrying artery, and then began to embolize AN while preserving the aneurysm-carrying artery. The balloon can be advanced or withdrawn at will to ensure the embolization of AN at the desired site and to preserve normal arterial blood flow, but the balloon must be filled with silicone fluid or curing agent to prevent balloon shrinkage and recurrence of AN; the balloon and the delivery catheter are flexible, poorly controllable, difficult to operate, and cannot conform to the shape of AN and are prone to rupture. In 1991, Giglielmi of Italy designed the electrolytic detachable spring coil (GDC), which was considered a revolutionary development and caused a debate on what is the preferred treatment for clamping and embolization; GDC is flexible and controllable, and the operation is convenient and safe. The rate of complete occlusion of small-necked AN is as high as 70%-85%, while complete occlusion of wide-necked or shuttle-shaped AN is more difficult; some scholars adopted double-bending plasticity, transverse basket, extra-basket filling and divisional filling techniques; ML, Moret et al. applied the technique of neck reshaping to improve the rate of occlusion; after that, super-soft and anti-rotation GDC, mechanically disengaging spring ring (MDS), new generation of GDC and MDS were introduced. (For wide-necked AN, ordinary spring coils often fail to densify or protrude into the tumor-bearing artery, Cloft et al. and Malelt et al. reported that three-dimensional GDC can be used to form a basket in three dimensions, avoiding instability during release; Turk et al. (3) Liquid embolic agent: The principle of liquid embolic agent embolization therapy is to enter the aneurysmal artery through the liquid embolic agent. Mlira, Yama et al. attempted to inject ONYX after balloon protection to reduce the risk of distal embolization; liquid embolic agents can conform to the AN morphology of AN morphology solidification, reduce residual dead space, and achieve complete occlusion, if it can Liquid embolic agents are very promising if they do not drift to distant areas after embolization and the problem of embolic agent toxicity can be solved; ④ Endovascular stent: when embolization with GDC alone is not feasible for wide-necked or shuttle-shaped AN, stent combined with GDC should be applied to achieve the purpose of cure; Higkishida first reported the clinical treatment of AN by stent placement combined with spring ring in 1997, and this treatment was started in China in 2000. In 2000, this treatment method began to be carried out in China, and there are reports of mesh stents combined with GDC for wide neck and shuttle AN; mesh stents have been paid more and more attention, and more coronary stents are used at present. Self-expanding stents, balloon-expanding stents, coated stents, heparinized stents and reflex stents have also emerged, and although they are not yet widely used in clinical practice, they have a tendency to gradually replace coronary stents.
The endovascular treatment of AN has made rapid development, but there are still some immature aspects, how to improve embolization techniques and embolization materials to improve the degree of embolization, reduce recurrence and rebleeding has become a hot spot of research, how to make the operation safe and easy, so that the endothelium covers the neck of the aneurysm and achieve anatomical cure is the direction of future research.
References (omitted)