Sphenopalatine Ganglion Stimulation Research Articles

Preventive treatment of refractory chronic cluster headache: systematic review and meta-analysis.

Preventive treatment for refractory chronic cluster headache (rCCH) is challenging and many therapies have been tried. To study what could be considered the therapy of choice in rCCH through a systematic review and meta-analysis. This review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The protocol was registered in PROSPERO (ID CRD42021290983). A systematic search was performed in MEDLINE, Embase, Cochrane, clinicaltrials.gov, and the WHO's-International-Clinical-Trials-Registry-Platform. Studies on the preventive treatment for rCCH as defined by the European Headache Federation consensus statement were included. A meta-analysis of the pooled response rate was conducted for the different therapies. Of 336 results, 45 were eligible for inclusion. Most articles studied the effect of neuromodulation as a preventive treatment for rCCH. The most studied neuromodulation technique was occipital nerve stimulation (ONS), with a pooled response rate in the meta-analysis of 57.3% (95% CI 0.481-0.665). Deep brain stimulation (DBS) was the second most studied treatment with a pooled response rate of 77.0% (95% CI 0.594-0.957). DBS results were more heterogeneous than ONS, which could be related to the different stimulation targets in DBS studies, and reported more serious adverse events than in ONS studies. The remaining therapies (anti-CGRP pathway drugs,warfarin, ketamine-magnesium infusions, serial occipital nerve blocks, clomiphene, onabotulinum toxin A, ketogenic diet, sphenopalatine ganglion radiofrequency or stimulation, vagus nerve stimulation, percutaneous bioelectric current stimulation, upper cervical cord stimulation, and vidian neurectomy) present weaker results or have less quality of evidence. The results of this systematic review and meta-analysis suggest that ONS could be the first therapeutic strategy for patients with rCCH based on the current evidence.

Simultaneous Sphenopalatine and Occipital Nerve Stimulation in Treatment of Chronic Refractory Cluster Headache: A Case Report

Among various interventions, surgery for cluster headache (CH) includes electrical stimulation of ipsilateral or bilateral occipital nerve(s) (ON), supraorbital nerve, sphenopalatine ganglion (SPG), and hypothalamus (hypothalamic deep brain stimulation [DBS]). There is no established and universally accepted algorithm for choice of surgical approach due to insufficient evidence base and reported variable results. 1 Pedersen J. Barloese M. Jensen R. Neurostimulation in cluster headache: a review of current progress. Cephalalgia. 2013; 33: 1179-1193https://doi.org/10.1177/0333102413489040 Crossref PubMed Scopus (43) Google Scholar This article presents a successful case of simultaneous SPG and ON stimulation in a chronic refractory CH patient. Informed consent for publishing was obtained.

The efficacy of Intranasal Sphenopalatine Ganglion Stimulation (INSPGS) in Long COVID, and its Possible Mechanisms

After SARS-CoV-2 infection, it is known that various symptoms that last for several months or more persist as sequelae even after the virus is no longer detected by PCR, these are known as Long COVID (LC), Long-haul COVID, Post-COVID syndrome, Post-acute sequelae of SARS-CoV-2 infection (PASC).

Effects of acute and preventive therapies for episodic and chronic cluster headache: A scoping review of the literature.

Cluster headache is the most common primary headache disorder of the trigeminal autonomic cephalalgias, and it is highly disabling. We undertake a scoping review to characterize therapies to prevent and acutely treat cluster headache, characterize trial methodology utilized in studies, and recommend future trial "good practices." We also assess homogeneity of studies and feasibility for future network meta-analyses (NMAs) to compare acute and preventive treatments for cluster headache. A priori protocol for this scoping review was registered and available on Open Science Forum. We sought studies that enrolled adult patients with cluster headache as identified by accepted diagnostic criteria. Both randomized controlled trials (RCTs) and observational studies (with a control group) were included. The interventions of interest were medications, procedures, devices, surgeries, and behavioral/psychological interventions, whereas comparators of interest were placebo, sham, or other active treatments. Outcomes were predefined; however, we did not exclude studies lacking these outcomes. A systemic search was conducted in Ovid Medline, Embase, and Cochrane. We performed a targeted search for conference abstracts from journals prominent in the field. We identified 56 studies: 45 RCTs, four studies only available in clinical trial registries, and seven observational studies. Of the 45 RCTs, 20 focused on acute therapies and 25 on preventive therapies. Overall, we determined that it is feasible to pursue a NMA for acute therapy focusing on 15 or 30-min headache reduction for acute trials, as we identified 11 trials in the combined population of patients with either episodic or chronic cluster headache (2 trials in populations with chronic cluster headache were also found). For preventive therapy of cluster headache, we identified trials with common outcomes that may be considered for NMA, however, as these trials had differences in treatment effect modifiers that could not be corrected, NMAs appear infeasible for this indication. We identified new studies looking at noninvasive vagal nerve stimulation, sphenopalatine ganglion stimulation, prednisone, and oxygen published since the most recent systematic review in the field, although these acute treatments were previously identified as effective. However, for calcitonin gene-related peptide (CGRP) monoclonal antibodies, galcanezumab demonstrated effectiveness in episodic cluster headache, but a lack of effectiveness in chronic cluster headache, and fremanezumab was not effective for episodic nor chronic cluster headache. This finding highlights that CGRP monoclonal antibodies may not show a class effect in cluster headache prevention and need to be considered individually. We describe the treatment landscape of cluster headache for both acute and preventive treatments. Last, we present the NMAs we will undertake in acute therapies of cluster headache.

Neuromodulation for Prevention and Treatment of Headache Disorders

Neuromodulation is a treatment modality that can be used in the abortive and preventive treatment of migraine and other primary headache disorders. The basic concept of neurostimulation is to manipulate peripheral or central pain pathways with either magnetic or electrical impulses. Common neuromodulation techniques include occipital nerve stimulation, which is the oldest technique, and trigeminal nerve stimulation, combined occipital and trigeminal nerve stimulation, sphenopalatine ganglion stimulation, vagus nerve stimulation and transcranial magnetic stimulation, which were introduced soon after. The two newest modalities are remote electrical neuromodulation and caloric vestibular stimulation, the last of which is still in the experimental phases.

Sphenopalatine ganglion stimulation in the treatment of chronic refractory cluster headache. A preliminary multicenter study in Russia

To analyze the results of sphenopalatine ganglion stimulation in treatment of chronic headache. Medical histories of patients who underwent sphenopalatine ganglion stimulation in 4 clinical centers have been analyzed. The analysis included the type of pain and its characteristics, methods of surgery, CT, MRI, radiography before and after surgery. The follow-up data of patients with implanted pulse generators was collected in an outpatient clinic or by telephone review. The study included 15 patients with chronic refractory headache, including 14 with cluster headache and one female patient with features of trigeminal autonomic cephalgia without a clear definition of the type of pain. Trial stimulation was performed in 10 patients to determine analgesic effect. Among them stimulation was favorable in 7 cases, and 6 of them underwent pulse generator implantation. In total, 11 (73%) patients underwent implantation with a follow-up from 1 to 60 months. Among them only 6 (54%) patients use stimulation, the remaining 5 (46%) cases had device-related complications (migration, infection of system). Cluster headache has a significant improvement in long-term follow-up. Sphenopalatine ganglion stimulation may have high potential in the treatment of chronic drug-resistant cluster headache. The complication rate demonstrates that operative technique should be improved.

Cluster Headache: Epidemiology, Pathophysiology, Clinical Features, and Diagnosis

Cluster headache is a primary headache disorder and is the most prevalent of the trigeminal autonomic cephalalgias. Cluster headache significantly impacts those affected, necessitating early diagnosis and management. Despite unique clinical features, such as patients experiencing attacks in a circannual pattern and often with a circadian rhythm within bouts, cluster headache patients often are misdiagnosed, mismanaged and have a delay in diagnosis. Preclinical, neuroimaging and clinical studies have advanced our understanding of cluster headache pathophysiology. The trigeminovascular system, the trigeminal autonomic reflex, and the hypothalamus are all involved in the pathophysiology of cluster headache. As our understanding of the pathophysiology of cluster headaches has evolved, new therapeutic options, such as calcitonin gene-related peptide monoclonal antibodies, non-invasive vagal nerve stimulation and sphenopalatine ganglion stimulation, have proved to have efficacy in the treatment of cluster headache. Herein, we aim to review developments to aid readers in their understanding of this debilitating disorder.

Accuracy of Electrode Position in Sphenopalatine Ganglion Stimulation in Correlation With Clinical Efficacy

Sphenopalatine ganglion (SPG) stimulation is an efficient treatment for cluster headache. The target for the SPG microstimulator in the pterygopalatine fossa lies between the vidian canal and foramen rotundum, ideally two contacts should be placed in this area. However, placement according to the manufacturers recommendations is frequently not possible. It is not known whether a suboptimal electrode placement interferes with postoperative outcomes. SPG stimulation was performed in 13 patients between 2015 and 2018 in a single center. Lead location was determined by intraoperative computed tomography scan and correlated with the planned lead position as well as clinical data and stimulation parameters. Patients with a reduction of 50% or more in pain intensity or frequency were considered responsive. Eleven patients (84.6%) responded to SPG stimulation with eight being frequency responders (61.5%). In seven cases, there were less than two electrodes between vidian canal and foramen rotundum, there was no significant correlation with negative stimulation results (p=0.91). The mean distance of lead location between pre- and postoperative images did not correlate with clinical outcomes (p=0.84) and was even bigger in responders (4.91 mm vs. 4.53 mm). The closest electrode contact to the vidian canal was in the stimulation area in all but one patient, regardless of its overall distance to canal. The distance of the closest electrode to the vidian canal was, however, not significantly correlated to the percentage of frequency (p=0.68) or intensity reduction (p=0.61). There was no significant correlation regarding aberrations of lead position from the planned position with clinical outcome. However, this study might be underpowered to detect such a correlation. The closest electrode contact to the vidian canal was in the stimulation area in all but one patient in the final programming. This indicates that, overall, the lead location does play a crucial role in SPG stimulation for cluster headache.

Update on Treatment of Cluster Headache

Cluster headache (CH) is characterized by severe unilateral short-lasting headache attacks, accompanying ipsilateral cranial autonomic symptoms or the sense of restlessness and agitation, or both. CH is a highly disabling primary headache disorder but often not optimally treated. High-flow oxygen and parenteral triptans are the most effective treatment to treat an acute CH attack. Transitional treatments include systemic steroid therapy and sub-occipital steroid injection. For preventive therapy, verapamil and lithium are recommended as first-line treatments. Novel treatments have appeared, such as neuromodulation and medication targeting calcitonin gene-related peptide (CGRP) or its receptor. Galcanezumab, the only anti-CGRP receptor monoclonal antibody with proven efficacy for the preventive treatment of episodic CH, represents an important advance for pharmacological treatment of CH. Neuromodulation strategies, such as the non-invasive vagus nerve stimulation and the sphenopalatine ganglion stimulation, have been proven effective in reducing the intensity and frequency of attacks, and also to be safe and well tolerated.

New Management of Cluster Headache

Galcanezumab, a CGRP monoclonal antibody drug, has been approved by the U.S. Food and Drug Administration (FDA) for the prevention of recurrent cluster headaches. This was done after a randomized, double-blind, placebo-controlled trial found it to be effective and safe. Similarly sphenopalatine ganglion stimulation has been found to be effective and safe in a randomized, controlled trial as an acute treatment for chronic cluster headache. This article reviews the mechanisms of action of these therapies and their clinical trial results, clinical uses, and prospects in Japan.

Cluster headache pathophysiology - insights from current and emerging treatments.

Cluster headache is a debilitating primary headache disorder that affects approximately 0.1% of the population worldwide. Cluster headache attacks involve severe unilateral pain in the trigeminal distribution together with ipsilateral cranial autonomic features and a sense of agitation. Acute treatments are available and are effective in just over half of the patients. Until recently, preventive medications were borrowed from non-headache indications, so management of cluster headache is challenging. However, as our understanding of cluster headache pathophysiology has evolved on the basis of key bench and neuroimaging studies, crucial neuropeptides and brain structures have been identified as emerging treatment targets. In this Review, we provide an overview of what is known about the pathophysiology of cluster headache and discuss the existing treatment options and their mechanisms of action. Existing acute treatments include triptans and high-flow oxygen, interim treatment options include corticosteroids in oral form or for greater occipital nerve block, and preventive treatments include verapamil, lithium, melatonin and topiramate. We also consider emerging treatment options, including calcitonin gene-related peptide antibodies, non-invasive vagus nerve stimulation, sphenopalatine ganglion stimulation and somatostatin receptor agonists, discuss how evidence from trials of these emerging treatments provides insights into the pathophysiology of cluster headache and highlight areas for future research.

Sphenopalatine Ganglion Stimulation Upregulates Transport of Temozolomide across the Blood-Brain Barrier

Sphenopalatine ganglion (SPG) stimulation has been shown to reversibly alter blood-brain barrier (BBB) permeability. It is widely used for the treatment of cluster headaches in Europe and is well tolerated in humans. The therapeutic potential for SPG stimulation in other central nervous system (CNS) diseases has yet to be explored. Glioblastoma Multiforme (GBM) remains one of the most difficult primary CNS neoplasms to treat, with an average survival of approximately 18 months at the time of diagnosis. Since 2004, the gold standard of treatment for GBM in the United States includes surgery followed by treatment with temozolomide (TMZ) and radiation. We sought to determine if SPG stimulation could increase chemotherapy concentrations in rodent brains with an intact BBB. Here, we show a statistically significant (p = 0.0006), five-fold upregulation of TMZ crossing the BBB and reaching brain parenchyma in rats receiving low-frequency (LF, 10 Hz) SPG stimulation. All the measurements were performed using a highly sensitive liquid chromatography mass spectrometry (LCMS) method that was developed for quantitation of TMZ in plasma and brain tissue. Our treatment paradigm shows novel delivery route by which we could more effectively and safely deliver TMZ in a targeted manner, to minimize systemic toxicity and maximize action at the target tissue.

Mechanisms of action of acute and subacute sphenopalatine ganglion stimulation for ischemic stroke.

Sphenopalatine ganglion stimulation (SPG-Stim) for ischemic stroke, starting 8-24 h after onset and continuing through five days in a pooled analysis of two recent, randomized, sham-controlled trials, improved outcome of acute ischemic stroke patients with confirmed cortical involvement. As a neuromodulatory therapy, SPG-Stim differs substantially from existing pharmacologic (lytic and antiplatelets) and device (endovascular thrombectomy) acute ischemic stroke treatments. Focused review of SPG anatomy, physiology, and neurovascular and neurobiologic mechanisms of action mediating benefit of SPG-Stim in acute ischemic stroke. Located posterior to the maxillary sinus, the SPG is the main source of parasympathetic innervation to the anterior circulation. Preclinical and human studies delineate four distinct mechanisms of action by which the SPG-Stim may confer benefit in acute ischemic stroke: (1) collateral vasodilation and enhanced cerebral blood flow, mediated by release of neurotransmitters with vasodilatory effects, nitric oxide, and acetylcholine, (2) stimulation frequency- and intensity-dependent stabilization of the blood-brain barrier, reducing edema (3) direct acute neuroprotection from activation of the central cholinergic system with resulting anti-inflammatory, anti-apoptotic, and anti-excitatory effects; and (4) neuroplasticity enhancement from enhanced central cholinergic and adrenergic neuromodulation of cortical networks and nitrous oxide release stimulating neurogenesis. The benefit of SPG-Stim in acute ischemic stroke is likely conferred not only by potent collateral augmentation, but also blood-barrier stabilization, direct neuroprotection, and neuroplasticity enhancement. Further studies clarifying the relative contribution of these mechanisms and the stimulation protocols that maximize each may help optimize SPG-Stim as a therapy for acute ischemic stroke.

Abstract 114: Diverse Patients Show Physiologic Benefit From Refined Sphenopalatine Ganglion Electrode Placement and Stimulation Level Selection to Augment Blood Flow and Neurologic Function in Acute Ischemic Stroke (The IMPACT-24M Trial)

Background: Two large RCTs have indicated sphenopalatine ganglion (SPG) stimulation reduces 3m disability in acute ischemic stroke patients with confirmed cortical involvement. The current trial evaluated two refinements in SPG stimulation technique: 1) SPG electrode placement with real-time optical tracking guidance; and 2) stimulation intensity comfortable tolerance level (CTL) selection using non-noxious facial physiologic markers. Methods: Single, active arm trial at 4 centers, enrolling patients with anterior circulation ischemic stroke <24h, NIHSS 1-6, not receiving recanalization therapies. Stimulation level was based on ipsilateral facial tingling sensation or lacrimation. SPG stimulation effects were assessed by volumetric blood flow in the ipsilateral common carotid artery (ultrasound) and affected hand grasp and pinch strength before and during stimulation, and by NIHSS change by day 7. Results: Among 50 enrolled patients, age was median 66y (IQR 60-74), 44% female, NIHSS median 5 (IQR 4-5), and median onset-to-screening time 18h (IQR 9-20). Median implantation skin-to-skin time was 4 minutes (IQR 3-7) and all 50 implants were placed correctly. CTL was found based on physiological biomarkers in 96% of patients, including 86% in the optimal, low-medium intensity range. SPG stimulation significantly increased common carotid artery peak systolic and end diastolic blood flow (up 44%, p<0.0001; and up 52%, p<0.0001) and improved pinch strength (up 42%, p<0.0001) and grasp strength (up 26%, p<0.0001). Degree of NIHSS recovery by day 7 was greater than in matched historic controls, median 75% vs 50%, p=0.0003. Forest plot analysis showed benefits were homogenous across the subgroups of: sex, age, time from onset, stroke side, NIHSS, and ASPECTS score. Conclusion: SPG stimulator placement with real-time optical tracking guidance was fast and accurate, and selection of optimal stimulation intensity levels based on non-noxious facial tingling and lacrimation was feasible in nearly all patients. SPG activation led to cranial blood flow augmentation and improved hand motor function during stimulation, and neurologic deficit reduction at 1 week, consistently across broad patient subsets of age, sex, side, severity, and time to treatment.

Abstract 11: Assessing the True ImpACT-24B: Magnitude of Benefit of Sphenopalatine Ganglion Stimulation for Acute Ischemic Stroke with Confirmed Cortical Involvement

Background: Sphenopalatine ganglion (SPG) stimulation enhances collateral flow, stabilizes blood-brain barrier, and showed evidence of benefit in patients with confirmed cortical involvement (CCI) when started 8-24h after onset in the ImpACT-24B randomized trial. To characterize SPG stimulation benefit magnitude, we derived number needed to treat (NNT) values based on shifts over all levels of 3 month global disability. Methods: From the distribution of the 7-level modified Rankin Scale (mRS) at 3m in SPG- and sham-stimulation CCI patients, NNT to benefit (NNTB) and NNT to harm (NNTH) values were derived by automated (algorithmic min-max) and expert generation of joint outcome distribution tables. For dichotomized mRS outcomes, net NNT values were derived directly from absolute risk differences. Results: Among 520 patients with confirmed cortical infarction ineligible for thrombolysis, 244 were treated with SPG and 276 with sham stimulation. NNT values for dichotomized and shift mRS outcomes are shown in the Table. Of the 6 possible binary cutpoints on the mRS, 4 showed more favorable outcome with SPG stimulation. The dichotomized endpoint with the greatest group difference was ambulatory and capable of bodily self-care (mRS 0-3), 62.3% vs 51.1%, NNTB 8.9. Across all 6 individual possible dichotomizations of the mRS, the NNTB ranged from 8.9 to -166.7. For shifts by 1 or more levels across all 6 transitions of the mRS, the biologically most plausible NNTB was 5.7 (IQR 5.6-6.5), NNTH 34.5 (IQR 30.3-40.0), and net NNTB 6.8 (IQR 6.5-7.7), These values correlated closely with the automatically derived net NNTB of 5.9. Conclusions: The findings of this pivotal trial indicate that, out of every 1000 CCI patients treated with SPG stimulation, 146 patients will have a less disabled 3-month outcome, including 76 more who will be functionally independent. SPG stimulation can substantially improve the outcome of thrombolysis-ineligible acute ischemic stroke patients.

Sphenopalatine Ganglion Stimulation for Chronic Headache Syndromes.

Neuropathic facial pain is notoriously difficult to treat, regardless of its origin and duration. Since the first reported sphenopalatine ganglion blockade by Sluder in 1908, this ganglion has assumed an important role among the structures targeted for the treatment of facial pain. Recent years have witnessed the rise of neuromodulation over ablative procedures, including the development of an implantable stimulation device specially designed for use in the pterygopalatine fossa. Sphenopalatine ganglion stimulation has been demonstrated as effective and safe for refractory cluster headache, today the major indication for this therapy, but increasing evidence shows that the effect on the autonomic system and cerebral circulation could justify an even wider use of sphenopalatine ganglion stimulation for other chronic headache syndromes and vascular diseases.

Occipital Nerve Stimulation and Sphenopalatine Ganglion Stimulation for Treatment of Intractable Headache Syndromes.

Headaches are an increasing cause of disability in the world. Intractable headache syndromes affect all age groups but predominantly the middle-aged, working population. Occipital neuralgia is a frequent comorbidity with intractable migraine headaches. Occipital nerve stimulation at the level of nuchal ridge is a reasonable option for these refractory patients. Ultrasound guidance of occipital nerve stimulation can optimize depth placement of leads. Revision surgeries of occipital nerve stimulation are usually performed using surgical leads. Cluster headaches and trigeminal autonomic cephalagias (TACs) are refractory headache conditions that are mediated by sphenopalatine ganglion. Sphenopalatine ganglion stimulation with infrazygomatic approach and fluoroscopic guidance of percutaneous leads can help alleviate pain from cluster headaches and TACs. Innovation in neurostimulation technologies have brought new optimism to these refractory conditions. Efficient and optimal delivery of neurostimulation for intractable headache syndromes requires a multidisciplinary team-based approach for long term compliance and efficacy.

Peripheral Nerve Stimulation for Facial Pain Using Conventional Devices: Indications and Results.

Trigeminal branch stimulation is a type of peripheral nerve stimulation (PNS) used to treat a variety of craniofacial pain disorders. Common indications include trigeminal neuralgia, trigeminal neuropathic pain, trigeminal deafferentation pain, trigeminal postherpetic neuralgia, supraorbital neuralgia, and migraine headaches. Supraorbital and infraorbital arrays are the most common electrode configurations, although preauricular, mandibular branch, and subcutaneous peripheral nerve field stimulation arrays have also been described. Trigeminal branch stimulation may be used as a stand-alone neuromodulation therapy or it may be combined with occipital nerve, sphenopalatine ganglion, or Gasserian ganglion stimulation to treat more complex pain patterns. Consistent with other forms of PNS, trigeminal branch stimulation is a minimally invasive, safe, and straightforward method of treating medically refractory neuropathic pain.

Location and Volume of MRI Artifacts in Patients With Implanted Sphenopalatine Ganglion Neurostimulators for Treatment of Chronic Cluster Headache

Sphenopalatine ganglion stimulation (SPG-S) is an invasive form of neuromodulation by which a neurostimulator is implanted into the pterygopalatine fossa to treat refractory chronic cluster headache. The implant is MRI conditional, up to 3 T, however there is no clinical data on the shape, size, and location of the artifact produced by the implant. Records of patients with SPG-S were analyzed for postoperative cranial MRI scans. MRI and intraoperative CT scans for visualization of the implant were fused and volumetry was performed for both the implant and the MRI artifact in different MRI sequences. In total, n = 3 patients with postoperative MRI scans were identified. The mean CT artifact volume was 0.73 cm3 (±0.15 cm3 ). MRI artifact volume differed between sequences (range: 25.2-220.7 cm3 ). The intracranial space was largely unaffected besides the pole of the ipsilateral temporal lobe and the basal frontal gyrus. MRI artifacts affected the extracranial space (orbit, maxillary and ethmoid sinuses, and parts of the parotid gland). No adverse events occurred during or after MRI scans. Cranial MRI scans with SPG-S implants were safely performed in three patients following the manufacturer's MRI conditions. MRI artifacts were mostly located in the extracranial space. Brain MRI imaging is largely unaffected. The authors declare no potential conflicts of interest with respect to research, authorship, and/or publication of this article.

Refined Sphenopalatine Ganglion Stimulator Placement and Intensity Setting to Augment Blood Flow and Neurologic Function.

Background and Purpose- Two large, randomized trials indicated that sphenopalatine ganglion (SPG) stimulation improves final disability outcome in acute anterior circulation patients with ischemic stroke with confirmed cortical involvement. This study evaluated 2 refinements in SPG stimulation treatment technique: (1) SPG electrode placement with real-time optical tracking guidance; and (2) stimulation intensity comfortable tolerance level selection using non-noxious facial physiological markers. Methods- This study was a single, active arm trial at 4 centers, enrolling patients with anterior circulation ischemic stroke, National Institutes of Health Stroke Scale 1 to 6 including arm weakness subitem score ≥1, not receiving recanalization therapies, and within 24 hours of onset. Stimulation level was set based on ipsilateral facial tingling sensation or lacrimation. SPG stimulation effects were assessed by measuring volumetric blood flow in the ipsilateral common carotid artery by ultrasound and grasp and pinch strength in the affected hand before and during stimulation, and by change in National Institutes of Health Stroke Scale from day 1 to 7. Results- Among 50 enrolled patients, age was median 66 years (interquartile range, 60-74), 44% were female, National Institutes of Health Stroke Scale median was 5 (interquartile range, 4-5), and median onset-to-screening time was 18 hours (interquartile range, 9-20). Median implantation skin-to-skin time was 4 minutes (interquartile range, 3-7), and all 50 implants were placed correctly. Comfortable tolerance level was found based on physiological biomarkers in 96% of patients, including 86% in the optimal, low-medium intensity range. SPG stimulation significantly increased common carotid artery peak systolic and end-diastolic blood flow (44%, P<0.0001; and 52%, P<0.0001) and improved pinch strength (42%, P<0.0001) and grasp strength (26%, P<0.0001). Degree of National Institutes of Health Stroke Scale recovery by day 7 was greater than in matched historic controls, median 75% versus 50%, P=0.0003. Conclusions- SPG stimulator placement with real-time optical tracking guidance was fast and accurate, and selection of stimulation intensity levels based on non-noxious facial tingling and lacrimation was feasible in nearly all patients. SPG stimulation led to cervico-cranial blood flow augmentation and improved hand motor function. Clinical Trial Registration- URL: https://www.clinicaltrials.gov. Unique identifier: NCT03551093.