Impact of Stellate Ganglion Block in the Management of Cerebral Vasospasm: A Prospective Interventional Study

BACKGROUND

Stellate ganglion block (SGB) causes blockage of sympathetic nerve activity, which may lead to intracerebral vessel dilatation and relieve cerebral vasospasm in patients of aneurysmal subarachnoid hemorrhage (aSAH).

OBJECTIVE

The aim of this study was to evaluate the efficacy and safety of SGB to relieve cerebral vasospasm on clinicoradiological parameters.

MATERIALS AND METHODS

We prospectively included 20 patients with clinical and angiographic evidence of vasospasm post aneurysmal clipping. Cerebral blood flow velocity and Lindegaard ratio were assessed using transcranial Doppler (TCD). Location of vasospasm, vessel diameter, vasospasm severity, parenchymal filling time, and venous sinus filling time were assessed on digital subtraction angiography (DSA). Patients received ultrasound-guided SGB with 10 mL of 0.5% bupivacaine on the ipsilateral side of the vasospasm. After 30 minutes, the neurological status, TCD, and DSA parameters were reevaluated.

RESULTS

After SGB, there was statistically significant reduction in the middle cerebral artery (MCA) peak systolic velocity (P = 0.005), mean flow velocity (P = 0.025), and Lindegaard ratio (P = 0.022) on TCD. We observed significant dilatation in the mean vessel diameter measured at the mid-M1 segment of MCA (P = 0.003) and mid-A1 segment of ACA (P = 0.002) on DSA. The mean parenchymal filling time and mean venous sinus filling time decreased nonsignificantly after SGB (P = 0.163/0.104). Neurological improvement was observed in five (25%) patients.

CONCLUSION

SGB has positive clinicoradiological influence in the management of cerebral vasospasm of large vessels. However, its effect on cerebral microvasculature is limited and needs a larger database for further analysis.

Executive function is less sensitive to estradiol than spatial memory: performance on an analog of the card sorting test in ovariectomized aged rhesus monkeys

Functions supported by the frontal lobes are particularly sensitive to the detrimental effects of aging. Recent studies on postmenopausal women find that estrogen replacement therapy benefits performance on tasks dependent on the frontal lobes. To determine whether estrogen has a similar influence in a rhesus monkey model of menopause, we tested five aged, long-term ovariectomized rhesus monkeys in a modified version of the Wisconsin Card Sort test which had been adapted to the nonhuman primate. In this test, monkeys had to select 3-D objects based either on color (blue, red, yellow) or shape (block, tube, cup) and had to be able to switch their response as a function of reinforcement contingencies. The monkeys were treated with placebo and ethinyl estradiol (EE2, 450 ng/kg/day) in alternation with each successive test. Contrary to our hypothesis, estradiol treatment did not affect performance. Because previous studies in the same monkeys [Neurobiol. Aging 23 (2002) 589] had shown that EE2 improves performance on a spatial memory task dependent on the hippocampus, but not on another task dependent upon the frontal lobes (the delayed response), we conclude that executive processes may be less sensitive to the effects of estradiol than hippocampal-dependent tasks.