The purpose of this study is to evaluate whether general anesthesia or sedation technique is preferable during embolectomy for stroke, measured in terms of three months neurological impairment. In addition we study if there is any difference between the methods regarding complication frequency.

Stroke is a common cause of neurological disability. Early diagnosis of ischemic stroke now enables treatment with thrombolysis and / or endovascular therapy (embolectomy). In order to implement this procedure, the duration of which varies from 2-6 hours, the patient has to remain immobilized. Two techniques are currently used routinely to achieve this.

One technique is general anaesthesia, that will ensure that the patient is completely immobile throughout the procedure, which is an advantage from a neuroimaging perspective. A disadvantage is that preparation for, and the induction of anesthesia prolongs the time to embolectomy. Another disadvantage may be that the patient´s blood pressure drops during anesthesia, which could impair the brain blood supply and subsequently neurological outcome. The ability to evaluate the patient's neurological symptoms also disappears.

The second technique consists of sedation during surgery. The advantages of this technique are that the time to the beginning of embolectomy is getting shorter and the blood pressure becomes more stable. One drawback is that it cannot guarantee that the patient remains immobile throughout the procedure, which increases the risk of motion artifacts and may lead to the duration of embolectomy becomes prolonged. There is also a risk of hypoventilation and the patient aspirates during surgery.

Retrospective studies suggest that patients receiving general anesthesia have worse neurologic outcome three months after stroke. This could be explained by more or less pronounced anesthesia-induced episodes of hypotension, compared with lightly sedated patients with more stable blood pressure. In these retrospective analyzes, however, the patients who received general anesthesia were, neurologically speaking, more ill than patients who only received sedation. This may probably, at least in part, explain why anesthetized patients have a worse neurologic outcome. In these retrospective studies, many centers were involved, with various endovascular and anesthesia procedures.

Inclusion Criteria:Patients with acute stroke considered for thrombectomy and meeting the following inclusion criteria included:

1. the patient is ≥ 18 years

2. the patient has a CT angio verified embolization * and / or a NIHSS scores ** ≥ 10 (R) or 14 (L) depending on the side engagement

3. embolectomy (= groin puncture) started <8 hours after symptom onset

   • Embolus in one of the following arteries: internal carotid artery, anterior cerebral (A1 segment), cerebri media (M1 segment) and proximal cerebri media branches (M2 segment).

     • NIHSS (National Institutes of Health Stroke Scale). Patients with embolus in left hemisphere circulation require ≥ 14 points, while patients with embolus in the right hemisphere circulation require ≥ 10 points. This is because occlusion on the right side does not usually cause aphasia, a symptom that usually leads to higher total score of NIHSS.

Exclusion Criteria:

1. the patient must receive general anesthesia, for medical reasons, according to the responsible anesthesiologist
2. the patient cannot receive general anesthesia, for medical reasons, according to the responsible anesthesiologist
3. the patient has an embolization of posterior brain vessels
4. CT-confirmed intracerebral hemorrhage
5. spontaneous recanalization or spontaneous neurological improvement
6. any other reason that does not allow embolectomy (co-morbidities)
7. premorbid MRS ≥ 4