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Mechanical embolectomy performed with general instead of local anesthesia is associated with worse clinical outcomes and poorer survival, according to an article published online March 25, 2014, ahead of print in Stroke. Moreover, contrary to previous concerns, local anesthesia is not associated with increased risk of symptomatic intracranial hemorrhage or adverse events.

Researchers led by Alex Abou-Chebl, MD, of the Texas Stroke Institute (Plano, TX), analyzed data on 281 patients from 18 centers enrolled in the NASA (North American SOLITAIRE Stent-Retriever Acute Stroke) registry. Patients received intra-arterial therapy with the Solitaire FR device (eV3 Neurovascular, Irvine, CA) while under general (69.8%) or local anesthesia (30.2%).

Baseline characteristics of the groups were similar, though the patients who received local anesthesia tended to have lower mean National Institutes of Health Stroke Scale (NIHSS) scores (16.4 ± 5.8 vs 18.9 ± 6.9; P = 0.002). There was also a trend towards higher initial systolic blood pressure (mean, +4.3 mm Hg) in the local anesthesia group (P = 0.1).

Procedurally, local anesthesia patients experienced a longer time from symptom onset to groin puncture (395 min ± 254.1 min vs 337.4 min ± 207.5 min; P = 0.04), though door-to-groin-puncture times were similar (P = 0.96). Total procedural times were also comparable between the groups (P = 0.6). Patients in the local anesthesia cohort were much less likely to receive a balloon-guide catheter than were those in the general anesthesia group (22.4% vs 49.2%; P = 0.0001).

Recanalization success, defined as thrombolysis in cerebral infarction ≥ 2, was 72.94% in the local group and 73.6% in the general group (P = 0.9).

Keep It Local

Occurrences of symptomatic intracranial hemorrhage were 7.1% for local and 11.2% for general anesthesia (P = 0.4). Patients who received local anesthesia were more likely to have good 90-day neurological outcomes (modified Rankin Scale ≤ 2; 52.6% vs 35.6%; P = 0.01), and there was a trend towards lower mortality amongst those who received local anesthesia (23.1% vs 34%; P = 0.1).

Multivariable analysis showed that hypertension, NIHSS score, unsuccessful revascularization, nonutilization of balloon-guide catheter, and general anesthesia were independently associated with mortality. Poor clinical outcome was predicted by the same factors apart from hypertension (table 1).

Table 1. Independent Predictors of Adverse Events: Local vs General Anesthesia

Excluding patients who were intubated for emergency reasons and had posterior circulation to control for possible confounders—so that use of general anesthesia was decided solely by user preference (n = 213)—those under local anesthesia experienced good outcomes at a higher rate compared to their counterparts who had general anesthesia (50.7% vs 35.5%; P = 0.04).

Effects on Blood Pressure, Operator May Explain Difference

The authors write that the results of this substudy are comparable to other recent studies showing a less advantageous effect of general anesthesia on patients with acute ischemic stroke undergoing intra-arterial therapy.

Exactly why general anesthesia imparts worse outcomes is unknown, the authors say. Common explanations, they explain, are that its use prohibits neurological assessment during the procedure and also may reduce blood pressure. In addition, patients treated with general anesthesia generally have slightly greater stroke severity, though in the current study, results remained comparable after adjustment for NIHSS score.

The mechanism by which lower blood pressure may lead to worse outcomes in unclear, but could be due to reduced cerebral blood flow to the ischemic penumbra potentially increasing the extent of injury, the authors say. “Also the deleterious effects of reduced arterial [blood pressure] may be potentiated by any increase in cerebral venous pressure, which has been noted to occur with [general anesthesia] and endotracheal intubation.”

In this substudy, patients who underwent local anesthesia had higher initial systolic blood pressure, which might further exacerbate the differences between the 2 groups, they say.

General anesthesia also inhibits the operator from being able to discern worsening conditions or adverse events. Because this study is retrospective, the authors explain, it is difficult to test the validity of this theory due to the lack of minute-by-minute procedural details or averted complications. There were instances during local anesthesia, however, where operators reported changing their endovascular technique because of patient-reported headache or suspected ischemia.

Fluoroscopy the Only Downside of Local

Longer fluoroscopy times are reported as the sole detrimental effect of local anesthesia. Dr. Abou-Chebl and colleagues posit that this “could be explained by the fact that procedures in awake patients may be prolonged because of the need to attend to the needs of the [conscious] and (sometimes) uncooperative patient and to (possibly) repeat angiographic runs because of motion artifact.”

“With the evidence mounting that [local anesthesia] is at least as safe as [general], especially with the planned use of Solitaire FR, the routine use of [general anesthesia] should be reconsidered.” Should it be used, the authors advise, “a discussion of these issues and close periprocedural collaboration… is recommended.”

Study Details

Information on the specific anesthetic used in this study is unavailable, thus potential neurotoxicity/neuroprotective components are also unknown.

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