Table 1

Human studies characteristics, vessel diameter measurement and neurological findings

First author, year	Type of study	Number of patients, age	Block technique	Vessel diameter measurement	Time of vessel diameter measurement	Findings	Neurological changes
Treggiari et al,27 2003	Prospective, observational	9 41±17	Fluoroscopy	DSA	To diagnose CAV and repeated after the block	Arterial delay, from 0.9±0.6 to 0.2±0.3 s (P<0.05) and parenchymal defect from 2.5±1.5 s to 1.1±1.5 s (P<0.05) after the block. Unchanged vessel diameter	Clinical improvement with complete symptom resolution in 6 patients
Jain et al,33 2011	Prospective, no control	15 45.5±13.6	Surface landmarks using anterior paratracheal approach	TCD	Before the block, 10 and 30 min, 2-6,12 and 24 hours after the block	Ipsilateral to CSB: mean MCA velocity, from 134 (8, SE) to 110 (6) at 6 hours and 113 (6) cm/s (P<0.001) at 24 hours after the block; mean ACA velocity: from 106 (6) to 94 (5) at 6 hours and 96 (5) cm/s (P<0.001) at 24 hours after the block. Contralateral to CSB: mean MCA velocity, from 96 (4) to 85 (4) cm/s (P<0.001) at 6 hours; mean ACA velocity from 74 (5) to 69 (5) cm/s (P<0.001) at 6 hours, in both vessels persisting for 12 hours after the block	Improvement in GCS after 30 min (p=0.002); 73% of patients had favorable outcome as measured by GOS at 6 months after SAH
Wendel et al,31 2020	Retrospective	37 49.9±11.1	Surface landmarks using anterior paratracheal approach	TCD	CBFV before the block, and at 2 and 24 hours afterwards	Ipsilateral MCA velocity: from 160±28 to 127±34 at 2 hours to 137±38 cm/s at 24 hours after the block corresponding to a 20% and 15% reduction	24 of the 37 patients significantly disabled (GOS ≤3) at ICU discharge, and moderately disabled (GOS 4) at 6 months follow-up
Pileggi et al,28 2021	Retrospective	10 Mean age 50.2 years, range 37–66	Fluoroscopy	DSA	Before the block in all patients, and in selected patients after the block	Angiographic vasodilation on the distal circulation	Average clinical outcome measured by modified Rankin Scale at discharge was 3 indicating moderate disability
Zhang et al,30 2021	Randomized controlled trial	SGB (n=50) 51.43±2.22. Non-SGB (n=52) 53.76±1.74	Ultrasound	TCD in the MCA and basilar arteries	The day before surgery (POD 0) and on POD 1-3-7	MCA and basilar arteries' velocities were higher on POD 1 and POD 3 compared with POD 0 in both groups, but this increase was lower in the SGB group (P<0.05)	Better neurologic prognosis score and neurological function 6 months after surgery in patients who received an SGB
Samagh et al,29 2022	Prospective, observational	20	Ultrasound	TCD and DSA	Before and after the block	TCD: reduction in ipsilateral systolic MCA velocity (from 150±22 to 140±24 cm/s, P=0.005), mean MCA velocity (from 120±23 to 108±25 cm/s, P=0.025), and Lindegaard ratio (from 2.57±0.46 to 2.34±0.50, P=0.022) after a CSB. DSA: increase in the mean vessel diameter measured at the mid‐M1 segment of ACA (from 0.109±0.049 cm to 0.124±0.0517 cm, P=0.002), mid‐A1 segment of MCA (from 0.174±0.046 cm to 0.189±0.0415 cm, P=0.003); decreased mean parenchymal filling time (from 3.18±0.37 s to 3.13±0.36 s, P=0.163) and venous sinus filling	Neurological improvement in 5 (25%) patients

ACA, anterior cerebral artery; aSAH, aneurysmal subarachnoid hemorrhage; CAV, cerebral arterial vasospasm ; CBFV, cerebral blood flow velocity; CBFV, cerebral blood flow velocity; CSB, cervical sympathetic block; DSA, digital subtraction angiography; GCS, Glasgow Coma Scale; GOS, Glasgow Outcome Score; ICU, intensive care unit; MCA, middle cerebral artery; POD, post-operative day; SAH, subarachnoid hemorrhage; SGB, stellate ganglion block; TCD, transcranial Doppler.