Jugular Venous Compression Collar for Prevention of Brain Injury due to Repetitive Head Impact and Concussion in Sport: A Scoping Review

Abstract

Context:

There is significant interest in jugular venous compression (JVC) devices from multiple parties, including sports physicians, athletic trainers, athletes, and parents.

Objective:

To examine the effects of JVC on repetitive head impacts and evaluate their effectiveness in reducing brain injury and concussion risk in sport.

Data Sources:

Embase, Cochrane Central Register of Controlled Trials, CINAHL Plus, SPORTDiscus, Web of Science Core Collection - SCI-EXPANDED, SSCI, AHCI, ESCI, American Psychological Association, PsycInfo, WHO International Clinical Trials Registry Platform (ICTRP), ProQuest Dissertations and Theses Citation Index (Web of Science), Europe PMC, and PubMed.

Study Selection:

Full-text, peer-reviewed manuscripts of primary research, published between 2010 and 2024.

Study Design:

Scoping review.

Level of Evidence:

Level 5.

Data Extraction:

A total of 22 articles met the inclusion criteria. These articles were categorized into 4 groups: animal models (n = 4), biomechanics in humans (n = 4), evidence in athletes (n = 11), and evidence in Special Weapons and Tactics Breacher Training (SWAT) (n = 3). Several of the athlete articles used the same cohort of athletes.

Results:

There was no difference in concussion rates in athletes between collared and noncollared groups during a season, while evidence from animal and tactical populations was limited to mechanistic and imaging outcomes. In both athletes and SWAT personnel, there were no clinically significant differences in neurocognitive performance between groups. There are statistically significant imaging changes between collared and noncollared groups; however, the imaging changes were not consistent and are of uncertain clinical significance. Furthermore, 6 out of 11 studies in athletes are currently under investigation. The available evidence supports that JVC can increase intracranial pressure, but it remains unknown if this results in any clinically meaningful benefit.

Conclusion:

Although no adverse outcomes are reported with collar use, current research does not support the effectiveness of JVC collars for concussion reduction and use for mitigation of repetitive head impact. Additional studies from diverse research teams with independent funding sources are required.

Keywords

DTI jugular venous compression neck collar repetitive head impact sports-related concussion

Repetitive head impacts, also termed subconcussive impacts, are head contacts that do not result in the clinical manifestation of a concussion.³ However, some authors suggest that the aggregation of such contacts over an athlete’s career may have deleterious neurophysiological impacts, including cognitive effects.^14,20 Moreover, some neuroimaging studies indicate that a single season of contact sports involving repetitive head impacts can alter brain networks as measured by diffusion tensor imaging (DTI).^2,7 Studies have shown that DTI metrics are sensitive to changes in white matter microstructure and can be altered after a concussion.²⁸

A specialized neck collar has been developed (Q-Collar, Q30 Westport) and is United States Food and Drug Administration (FDA) approved to aid in protection of the brain from the effects of repetitive subconcussive head impacts.³⁶ There is debate regarding the clinical effectiveness of such devices,¹³ and a more recent summary by the FDA was more measured in its support. The summary highlighted limitations including that the Q-Collar has not been demonstrated to prevent long-term cognitive function deficits, ultimate impact on clinical outcomes has not been evaluated, use of imaging studies as a future indicator of brain injury has not been validated, and data do not demonstrate that the device can prevent concussion or serious brain injury.³⁵ In addition, 6 studies that were submitted to the Journal of Neurotrauma are currently under investigation.^{24,29,38,40,41,43}

These devices apply pressure to the bilateral jugular veins and are proposed to provide brain “cushion” by increasing venous volume. This increase is intended to limit brain movement and lessen the impact of rapid acceleration/deceleration and tissue deformation.^4,15 This scoping review provides a comprehensive analysis of studies examining the effects of jugular venous compression (JVC) on repetitive head impacts in sports, as well as animal, biomechanical, and tactical-athlete studies. Specifically, it aims to determine whether a JVC collar reduces deleterious effects of repetitive head trauma, as observed through neuroimaging and neurocognitive task performance, and whether use of neck collars influences the frequency of head impacts as well as concussion rate.

Methods

This review was intended originally to be a systematic review, with the authors developing a protocol and registering it with PROSPERO. However, after conducting an initial screening of the studies and identifying gaps in the existing literature, there was insufficient literature to support a systematic review, so the project was transitioned to a scoping review format. This scoping review has now been registered with Open Science Framework and was carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-SCr) guidelines.³³

Search Strategy

The search strategy was created by a health sciences librarian using relevant seed studies related to JCV, repetitive head impact, and concussion outcomes provided by the authors. The search strings used controlled vocabulary and free text terms to increase search sensitivity in multiple databases. Databases used were Embase, Cochrane Central Register of Controlled Trials, CINAHL Plus, SPORTDiscus, Web of Science Core Collection-SCI-EXPANDED, SSCI, AHCI, ESCI, American Psychological Association, PsycInfo, WHO International Clinical Trials Registry Platform (ICTRP), ProQuest Dissertations and Theses Citation Index (Web of Science), Europe PMC, and PubMed. The search strategy for each database can be found in Supplemental Appendix I (available in the online version of this article). The search was limited to the years 2010 to 2024. Publications in languages other than English were excluded.

Study Selection

Searches were uploaded into Covidence, where they were de-duplicated. Inclusion criteria were studies examining the effect of JVC head injury, including repetitive head impact in English in animal models, athletes, and other groups where repetitive head impact is a concern (military/police). Studies were included if they discussed mechanisms or outcomes. Subsequently, the titles and abstracts were screened manually by 2 authors for relevance. Disagreements were resolved through discussion. Full-text screening was performed by both authors to see whether inclusion criteria were met, and disagreements were again resolved through discussion. Animal and tactical athlete studies were included to provide mechanistic context and were analyzed separate from studies conducted in athletes.

Data Extraction

Before data extraction, the authors agreed on information to be extracted. Extracted information included year of study, country of study, study participants, study type, study design, results, interpretation of findings, study funding, imaging outcomes, cognitive tests outcomes, and concussion rate.

Results

From 239 articles found using the searches, 22 were deemed relevant and included in this scoping review, as illustrated in the flow diagram in Figure 1. Of these 22 studies, 8 provide insight into the mechanism of action of JVC, 11 investigate Q-collar use in athletes, and 3 examine JVC in special weapons and tactical personnel.

Figure 1.

PRISMA-SCr flow diagram for this scoping review, created using Covidence. PRISMA-SCr, preferred reporting items for systematic reviews and meta-analyses extension for scoping reviews.

Animal models

Search results identified 4 studies in rats and swine that explored the mechanism of action of JVC and its potential to mitigate the effects of head impact. Two studies investigated the effects of JVC on brain injury using rat mild traumatic brain injury (TBI) models.^30,34 Smith et al³⁰ and Turner et al³⁴ reported a mean 31% increase in intraocular and intracranial pressures with the use of JVC, supporting the proposed mechanism of action. Both papers examined the effects of impact-acceleration TBI on rats with and without JVC. The studies found an 80% reduction in the number of amyloid precursor protein-positive (b-APP) axons,³⁰ a 48.7% to 59.1% reduction in degenerative neurons, a 36.8% to 45.7% decrease in reactive astrocytes, and a 44.1% to 65.3% reduction in microglial activation among rats with JVC compared with controls.³⁴ Although both studies had a small sample size, with only 10 experimental and 10 control animals, and assessed histological markers only 7 days post-TBI, their findings indicate potential protective effects of JVC for single impact head injury in a controlled setting.

Other studies used swine models to investigate the effect of JVC on TBI markers.^19,29 Mannix et al¹⁹ used a model allowing for neck rotation at impact and reported a reduction of histological markers after TBI, specifically the phosphorylated tau epitope AT8 and the inflammatory microglial marker IBA1. Conversely, Sindelar et al,²⁹ using a fixed-head TBI model with the intent to create brain hemorrhage, found no statistical difference in b-APP, neuronal degeneration, cerebral edema, or inflammatory infiltration in animals with JVD compression compared with controls, but did observe a reduction in total subarachnoid and intraparenchymal hemorrhage scores.

Overall, the applicability of these studies to sport-related repetitive head impact in supporting a decrease in harm from repetitive head impact is uncertain. In sports, there are multiple degrees of freedom of the neck after a blow to the head. Only 1 animal model allowed for rotational forces,¹⁹ and in 3 studies the neck was fixed.^29,30,34 The injury models used in these studies were limited by use of a single injury paradigm (vs repetitive head impact) and the magnitude of the applied forces was likely significantly more than those that occur with typical sports-related head impacts, with 1 study creating an injury leading to brain hemorrhage.²⁹ In addition, the collars used for these studies differed from commercial models tested in humans (Table 1).

Table 1.

Animal studies of JVC

Year	Author	Journal	Title	Participants	Study type	Study design	LoE	Results	Study funding
2012	Smith et al³⁰	Neurosurgery	Internal jugular vein compression mitigates traumatic axonal injury in a rat model by reducing the intracranial slosh effect	Adult male Sprague-Dawley rats with (n = 10) and without (n = 10) IJV compression	Controlled trial	Rats with and without IJV compression using a collar, were subjected to impact- acceleration TBI. Intracranial, intraocular pressure and axonal injury were measured	5	IJV compression resulted in a 30% increase in intraocular and intracranial pressures, as well as 80% reduction in the number of b-APP axons, a marker for axonal injury	None
2012	Turner et al³⁴	Journal of Neurosurgery	Effect of slosh mitigation on histologic markers of traumatic brain injury	Adult male Sprague-Dawley rats with (n = 10) and without (n = 10) IJV compression	Controlled trial	Two groups of 10 adult male Sprague-Dawley rats were subjected to impact-acceleration TBI, 1 group with IJV compression and 1 without. Brain tissue was subsequently stained for markers of neural degeneration and neuroinflammation in both groups	5	Compared with the controls, animals that had undergone IJV compression had a 48.7-59.1% reduction in degenerative neurons, a 36.8-45.7% decrease in reactive astrocytes, and a 44.1-65.3% reduction in microglial activation	West Virginia University, Department of Neurosurgery, and National Institutes of Health grant no. 5T32GM81741 (to R.C. Turner)
2017	Sindelar et al²⁹	Journal of Neurotrauma	Effect of internal jugular vein compression on intracranial hemorrhage in a porcine controlled cortical impact model	Twelve swine were randomized to placement of a bilateral IJV compression collar (CCI+collar) or control/no collar (CCI) before CCI injury		Test the safety of IJV compression in a large animal CCI mild TBI injury model and the resultant effects on hemorrhage	5	CCI+collar animals exhibited a significant reduction in total subarachnoid hemorrhage (P = 0.02-0.03) and intraparenchymal hemorrhage scores (P = 0.03-0.05), no statistically significant difference in scoring for the other markers of TBI (b-APP, neuronal degeneration, cerebral edema, or inflammatory infiltration)	Q30 Sports Science LLC, and NorthShore University Health System
2020	Mannix et al¹⁹	Neuroscience	Internal jugular vein compression collar mitigates histopathological alterations after closed head rotational head impact in swine: a pilot study	Swine, collar treatment (n = 8) and non collar treatment (n = 6), sham animals exposed to anesthesia only (n=2)	Randomized controlled trial	After single head trauma mimicking TBI with head allowed to rotate, swine were euthanized (3-5 days postinjury) and brains collected for histology	5	Internal venous compression collar mitigates changes in AT8 and IBA1 after mild TBI in a swine closed head injury model	CHB IDDRC and by philanthropic support from the National Hockey League Alumni Association and the National Football League. 30 Sports Innovations LLC

b-APP, amyloid precursor protein-positive; CCI, controlled cortical impact; IJV, internal jugular vein; JVC, jugular venous compression; LoE, level of evidence; TBI, traumatic brain injury.

Biomechanical Studies in Humans

Research in humans has demonstrated that JVC compression leads to an increase in jugular vein cross-sectional area,^10,16,37 as well as increased intracranial pressure,¹⁰ indicating the potential for decreased intracranial compliance or ability for brain deformation. Two studies used the Q-Collar,^16,37 and 1 study used a Velcro collar with 2 rectangular sponge pads placed over the internal jugular vein.¹⁰ DiCesare et al⁸ investigated the effects on wearing a collar for JVC on athletic performance and found no detrimental impacts during a range of physiologic and neurologic challenges mimicking competitive sport. These studies were small but support the view that JVC collars increase intracranial pressure and appear to be safe in the short term in controlled settings (Table 2).

Table 2.

Biomechanical studies in humans

Year	Author	Journal	Country	Title	Participants	Study type	Study design	LoE	Results	Study funding
2017	DiCesare et al⁸	Thieme	United States	The effects of external jugular compression applied during high intensity power, strength and postural control tasks	18 healthy adults (8 women, 10 men)	Nonrandomized experimental study	Assess the tolerance and acceptance of this device in a population of normal, healthy adults undergoing exertion while monitoring changes in their biomechanical, strength, power, and postural stability capabilities	4	Evaluation of vital biomechanics, postural control and dynamic stabilization, isokinetic strength, and power in this population showed no statistically significant effect of wearing a mild jugular vein compression neck device	Q30 Innovations
2017	Yeoh et al³⁷	Canadian Journal of Anesthesia	Canada	Internal jugular vein blood flow in the upright position during external compression and increased central venous pressure: an ultrasound study in healthy volunteers	Healthy adult volunteers, 12 subjects (4 women)	Nonrandomized experimental study	IJV CSA was measured in the volunteers in sitting position with IJV compression and during the Valsalva maneuver	4	After application of the cervical collar, there was a significant increase in the median CSAs of both IJVs; however, no significant change in the median blood flow in the right IJV. During the Valsalva maneuver, there was an increase in the median CSA of both the right and left IJV	None
2019	Joshi et al¹⁶	PLOS ONE	Canada	Influence of a neck compression collar on cerebrovascular and autonomic function in men and women	Healthy, young adult men (n = 8) and women (n = 8)	Randomized controlled crossover trial	Testing protocols completed twice, once with and without use of a Q-collar	2	Q-collar increases jugular CSA and is more prominent in women; Q-collar also decreases carotid artery CSA	York University, Faculty of Health, Canadian Foundation for Innovation, and the Ontario Research Fund to H. Edgell
2022	Dinsmore et al¹⁰	British Journal of Sports Medicine	Canada	Effect of a neck collar on brain turgor: a potential role in preventing concussions?	Nineteen young, healthy adult volunteers, (13 men and 6 women)	Nonrandomized experimental study	IJV compression was applied in the sitting position with an elastic adjustable neck collar comprising 2 rectangular sponge pads (2 cm × 3 cm) over the IJV bilaterally, just superior to the clavicle, a pressure of 20 ± 1 mmHg was achieved	4	After application of IJV compression, mean (SD) CSA for IJV increased from 0.10 cm² (SD, 0.5) to 0.57 cm² (SD, 0.37) and ONSD increased from 4.6 mm (SD, 0.5) to 4.9 mm (SD, 0.5)	No funding reported

CCI, controlled cortical impact; CSA, cross-sectional area; IJV, internal jugular vein; LoE, level of evidence; ONSD, optic nerve sheath diameter.

Evidence in Athletes

A total of 11 studies investigated the effects of wearing a collar inducing JVC on repetitive head impact in the sports of football (n = 6), women’s soccer (n = 5), and hockey (n = 1). All 11 studies were performed by similar author groups and funded by the manufacturer of a JVC collar. There appear to be overlapping cohorts with separate papers reporting different outcomes. It is unclear how many total athletes were represented. Of these studies, 4 (representing a total of 488 athletes) had the same national clinical trials registration.^9,11,24,40 These studies follow a cohort of athletes across 1 or 2 seasons, focusing on longitudinal changes in brain neuroanatomy and neurophysiology using neuroimaging. Impact sensors were used to detect and quantify repetitive head impacts. While all the studies show significant differences in neuroimaging results between the athletes wearing a collar and those without, the direction of differences in white matter DTI parameters varied (Table 3). Two studies reported on functional magnetic resonance imaging (MRI) (fMRI) blood oxygen level dependent (BOLD).^41,43 These studies examine oxygen uptake on MRI while performing a cognitive task. Both studies showed no differences in performance of pre- and postseason cognitive tasks; however, in the postseason, while both the noncollared group and the collared group had increases in fMRI BOLD signal, the increase was greater in some brain areas in the noncollared athletes.^41,43 Two studies included follow-up neuroimaging scans, both of which revealed a partial reversal of DTI changes observed in the noncollar group at 3 to 9 months postseason.^21,39 There is a lack of consensus regarding the clinical implications and potential long-term effects of the reported neuroimaging changes on neurophysiology and neuroanatomy.

Table 3.

Summary of DTI findings in noncollar group and collared group after 1 season ^a

Year	Author	Sport imaged	Group	N	Days postimpact imaging occurred (range)	DTI MD	DTI RD	DTI AD	DTI FA
2016	Myer et al²²	Hockey	NC	7	2.9 ± 1.8 (1-6)	⇑	⇑	⇔	⇔
			C	7		⇔	⇔	⇔	⇔
2016	Myer et al²³	Football	NC	21	5.83 ± 6.70	⇓	⇓	⇓	⇔
			C	21	7.05 ± 4.61	⇔	⇔	⇔	⇔
2018	Yuan et al⁴²	Football	NC	10	6.5 (3-20)	⇓	⇓	⇓	⇑
			C	12	5 (0-11)	⇔	⇔	⇔	⇔
2019	Myer et al²¹	Women’s soccer	NC	22	3.73 ± 4.33 (1-21)	⇓	⇓	⇓	⇔
			C	24	5.13 ± 5.25 (1-18)	⇔	⇔	⇔	⇔
2020	Diekfuss et al⁹	Football	NC	106	10.07 ± 11.58	⇓	⇓	⇓ ⇑	⇑
			C	107	11.01 ± 10.41	⇔	⇔	⇑	⇑
2021	Logan et al¹⁸	Women’s soccer	Year 2 NC	15	Not stated	⇓	⇓	⇓	⇔
			Year 1 C	15	Not stated	⇔	⇔	⇔	⇔
2021	Yuan et al⁴⁰	Football and women’s soccer	NC ^b	20 concussed athletes	Average 1 week postconcussion	⇑	⇑	⇑	⇓
			C ^b	20 concussed athletes	Average 1 week postconcussion	⇓	⇓	⇓	⇓

AD, axial diffusivity; C, collared athlete; DTI, diffusion tensor imaging; FA, fractional anisotropy; MD, mean diffusivity; NC, noncollared athlete; RD, radial diffusivity.

All studies analyzed DTI metrics in the white matter.

Athletes who suffered concussion.

There does not appear to be a difference in overall head impact counts across the sporting season between collar and noncollar groups, with only 1 small study in hockey (n = 15) reporting more head impacts in the collar compared with the noncollar group.²² These findings suggest little evidence for risk compensation or of players adjusting their behavior when wearing the collar (e.g., tackling with their head more because they felt protected).

Only 1 of the 11 studies in athletes reported concussion rates and found no difference between collared and noncollared groups. In this large study of 488 male football and female soccer athletes, the rate of concussion was 9.43% in the collared group compared with 10.13% in the noncollared group.⁴⁰ There were 40 athletes who underwent imaging an average of 7 days after the concussion; results showed that concussed athletes had white matter changes in axial diffusivity (AD), radial diffusivity (RD) and mean diffusivity (MD) but those wearing the collar had changes of a smaller magnitude.⁴⁰ A participant breakdown by sport and sex was not reported.

Four studies included pre- and postseason cognitive assessments and self-report questionnaires.^24,40,41,43 Three of the studies included the entire enrolled study population and did not report on whether any of the athletes had sustained a concussion during the season,^24,41,43 while the fourth study looked at pre and postseason cognitive assessments only in athletes who had been concussed during the season.⁴⁰ The neurocognitive tests included the N-back task assessing working memory; digital Trail Making Test assessing neuromotor control, attention and oculomotor function; the Strengths and Weaknesses of ADHD Symptoms and Normal Behavior Scale (SWAN); Cued Switching task; Post-Concussion Symptom Inventory; Attention Network Task (ANT); King-Devick (KD) test; and Flanker test assessing attention. These studies reported no significant differences between the collar and noncollar groups on most assessments.^24,40,41,43 However, 1 study reported a small but significant improvement in postseason performance of the collar group in the altering network scores of the ANT compared with the noncollar group, with the caveat of a small effect size with questionable clinical significance.²⁴ Yuan et al⁴⁰ documented improved performance among collared athletes on the KD over the course of a season when compared with noncollared controls. However, performance for both groups improved during the course of the season; therefore, the clinical significance of a reduced practice effect in the noncollared group is unclear (Table 4).

Table 4.

Studies of a JVC collar in athletes

Year	Author	Journal;clinical trials number	Title	Sport	Number	Study type	LoE	Primary outcome	Results	Concussion rate	Study funding
2016	Myer et al²²	Frontiers in Neurology	The effects of external jugular compression applied during head impact exposure on longitudinal changes in brain neuroanatomical and neurophysiological biomarkers: a preliminary investigation	Hockey	15C = 7NC = 8	Prospective, randomized controlled crossover study	2	Pre- to postseasonchanges in DTI andEEG-event related potentials	NC athletes had a statistically significant increase in MD and RD from preseason to postseason compared with collared athletes. Brain network activation score increased in NC relative to the C and correlated with DTI changes	Not reported	Q30 sports
2016	Myer et al²³	British Journal of Sport Medicine;NCT02696200	Analysis of head impact exposure and brain microstructure response in season-long application of JVC collar in American football	High school football	62C = 32NC =30	Prospective, longitudinal study	2	Pre- to postseason changes in DTI	Significant changes in DTI were noted in control group but not collar group	Not reported	Q30 Innovations
2017	Yuan et al⁴³	Journal of Neurotrauma;NCT02696200	Neck collar with mild jugular vein compression ameliorates brain activation changes during a working memory task after a season of high school football	High school football	C = 25NC = 27	Prospective, longitudinal study	2	Pre to postseason changes in fMRI doing N-Back test	No significant difference between the NC group and the C group was found in either the accuracy or response time.fMRI BOLD signal response during the working memory task increased significantly from pre- to postseason in the NC group, but not in the C group	Not reported	Q30 Innovations
2018	Yuan et al⁴¹	Journal of Neurotrauma	Mild jugular compression collar ameliorated changesin brain activation of working memoryafter 1 soccer season in female high school athletes	High school soccer	48C = 28NC = 21	Prospective, longitudinal study	2	Pre to postseason changes in fMRI doing N-Back test	No significant difference between the NC group and the C group was found in either the accuracy or response time.fMRI BOLD signal response during the working memory task increased significantly from pre- to postseason in the NC group, but not in the C group	Not reported	Q30 sports
2018	Yuan et al³⁹	Human Brain Mapping	White matter alterations over the course of 2 consecutive high-school football seasons and the effect of a jugular compression collar: a preliminary longitudinal DTI study	High school football	42C = 21NC = 21	Prospective, longitudinal study	2	Pre to postseason changes in DTI	Significant DTI MD, AD, and RD reduction in NC but not C group. Partial and significant reversal in NC group after 8- to 9-months off-season	Not reported	Q30 Sports Sciences
2019	Myer et al²¹	British Journal of Sports Medicine	Altered brain microstructure in association with repetitive subconcussive head impacts and the potential protective effect of jugular vein compression: a longitudinal study of female soccer athletes	High school soccer	46C = 24NC = 22	Prospective, longitudinal study	2	Pre-, postseason and off-season changes in DTI	Significant increases in DTI MD, RD, and AD in NC group and no significant change in C. WM changes partially resolved in NC group at 3 months postseason follow-up	Not reported	Q30 Sports Sciences
2020	Dudley et al¹¹	Brain Connect;NCT04068883	Altered functional and structural connectomes in female high school soccer athletes after a season of head impact exposure and the effect of a novel collar	High school soccer	128C = 72NC = 56	Prospective, longitudinal study	2	Pre- to postseason changes in rs-fMRI and DTI	NC exhibited significantly increased rs-fMRI-derived global clustering coefficients and DTI-derived modularity, compared with C athletes	Not reported	Q30 Innovations
2021	Diekfuss et al⁹	Journal of Neuroscience Research;NCT04068883	The effects of IJV compression for modulating and preserving white matter following a season of American tackle football: a prospective longitudinal evaluation of differential head impact exposure	High school football	284C = 139NC = 145	Prospective, longitudinal study	2	Pre to postseason changes in DTI	Pre-season to postseason reduction in MD, AD, and RD were seen in NC but not C group. No significant group difference in FA and AD increases were observed between the collar and the noncollar group	Not reported	Q30
2021	Logan et al¹⁸	Journal of Science in Sport and Exercise;NCT03014492	Is it possible to protect the adolescent brain with internal mechanisms from repetitive head impacts: results from a phase II single cohort, longitudinal, self-control study	High school soccer	15	Prospective, longitudinal study	4	Pre- and postseason changes in DTI scans over 2 years, collar worn in year 1 but not year 2	No pre- to postseason changes to MD, AD, or RD after year 1 (C year). Significant pre- to post-Season changes in MD, AD, and RD after year 2 (NC year)	Not reported	Q30 Innovations
2021	Yuan et al⁴⁰	Journal of Neurotrauma;NCT04068883	High school sports-related concussion and the effect of a jugular vein compression collar: a prospective longitudinal investigation of neuroimaging and neurofunctional outcome	High school football and soccer	488C = 251NC = 237Concussed athletesC = 22NC = 24	Prospective, longitudinal study	2	Concussion rate. Pre to postconcussion changes in DTI, neurocognitive and behavioral tests in athletes with concussion	No difference in concussion rate. Significant pre-season to postconcussion alterations in WM microstructural integrity and brain network organization were found in concussed athletes and the alterations were significantly reduced in C compared with NC. No differences in neurocognitive or behavioural tests	No difference	Q30
2022	Narad et al²⁴	Journal of Neurotrauma;NCT04068883	Effect of subconcussive head impact exposure and jugular vein compression on behavioral and cognitive outcomes after a single season of high-school football	High school football	284C = 135NC = 141	Prospective, longitudinal study	2	Pre to postseason behavioral outcomes	No differences between C and NC in parent and adolescent report on Strengths and weaknesses of ADHD symptoms and normal behaviour scale, postconcussion symptom inventory, digital trail making task, or cued switching performance. Attention network task scores were greater postseason in C group	Not reported	Q30 Sports Innovations

AD, axial diffusivity; BOLD, blood oxygen level dependent; C, collared athlete; DTI, diffusion tensor imaging; EEG, electroencephalogram; FA, fractional anisoptropy; fMRI, functional MRI; JVC, jugular venous compression; LoE, level of evidence; MD, mean diffusivity; MRI, magnetic resonance imaging; NC, noncollared athlete; RD, radial diffusivity; rs-fMRI, resting state functional MRI; WM, white matter.

In summary, these studies comparing groups of athletes wearing JVCs with those without show group differences in advanced neuroimaging metrics; however, the direction and magnitude of change is inconsistent and the clinical significance is unclear. All reviewed studies used a common JVC collar - the Q-Collar. Impact monitors included helmet-mounted sensors, X-patches, and G-Force sensors showed no differences in impacts, although these impact monitors have limitations which have been described previously.²⁵ There was no difference in concussion rate between collared and noncollared groups and there was no clinically significant difference between groups in neurocognitive testing. All of these studies were funded by the maker of the Q-Collar.

Evidence in Special Weapons and Tactics Breacher Training

We identified 3 studies in special weapons and tactics (SWAT) breacher training.^5,38,42 The studies used an impact monitor for blast exposure and evaluated a variety of imaging and cognitive outcomes in participants with and without a collar for JVC. One study conducted recurrence quantification analysis, a type of quantitative electroencephalogram (EEG), testing 2 days before and within 2 days after blast exposure, with 11 people in each group, and found participants in the noncollar group had longer periods of laminar electrocortical behavior after breacher training compared with the noncollared group.⁵ Another study investigated fMRI and cognitive changes in SWAT personnel after blast exposure and found significantly increased fMRI brain activation during the N-back working memory task and fMRI activity but no significant difference in performance on the N-back working memory task.³⁸

In a subsequent study, Yuan et al⁴² investigated MRI and neurite density index (NDI) changes using neurite orientation dispersion and density imaging (NODDI) - more sophisticated markers of grey matter change - 2 days before and 2 days after blast exposure and found a significant increase in NDI in the noncollar group from pre- to postblast exposure, but no significant difference in DTI changes between the 2 groups. These studies were limited by small samples sizes (Table 5).

Table 5.

Studies in tactical/breacher training

Year	Author	Journal	Country	Title	Participants	Study type	LoE	Primary outcome	Results	Study funding
2018	Bonnette et al⁵	Experimental Brain Research	United States	A jugular vein compression collar prevents alterations of endogenous electrocortical dynamics following blast exposure during special weapons and tactical (SWAT) breacher training	Local police SWAT team, C = 11, NC = 11	Prospective randomized, controlled trial	2	Quantitative EEG measured within 2 days before and within 2 days after SWAT breacher training	NC displayed longer periods of laminar electrocortical behavior after breacher training	Q30 Sports Innovations
2019	Yuan et al³⁸	Journal of Neurotrauma	United States	Impact of low-level blast exposure on brain function after a 1-day tactile training and the ameliorating effect of a jugular vein compression neck collar device	SWAT personnel,rs-fMRI C = 10, NC = 8fMRIC = 12,NC = 10	Prospective randomized, controlled trial	2	rs-fMRI and fMRI pre- and post-training	fMRI performance the same between both groups.NC group had greater activation during N-back post-training. No changes in C group.rs-fMRI showedsignificant pre- to post-training increase in connectivity between the auditory network and 2 discrete regions found in the NC group, no change observed in the C group	Q30 Sports Innovations
2021	Yuan et al⁴²	Military Medicine	US	White matter alteration following SWAT explosive breaching training and the moderating effect of a neck collar device: a DTI and NODDI study	SWAT personnel, C = 11,NC = 10	Prospective, longitudinal study	2	MRI measured within 2 days before and within 2 days after SWAT breacher training	The NC group exhibited significant pre- to postblast increase in NDI. A subset of these regions showed significantly greater alteration in NDI and isotropic volume fraction in the NC group when compared with those in the C group	Q30 Sports Innovations

C, collar; DTI, diffusion tensor imaging; EEG, electroencephalogram; fMRI, functional MRI; LoE, level of evidence; MRI, magnetic resonance imaging; NC, noncollar; NDI, neurite density index; NODDI, neurite orientation and density imaging; rs-fMRI, resting state functional MRI;SWAT, special weapons and tactical.

Discussion

This scoping review provides a comprehensive overview of the studies investigating the potential role of external JVC for mitigating repetitive head impact across a range of exposure contexts. Out of 239 screened articles, 22 met inclusion criteria, with 11 in studies in athletes, of which many appeared to have overlapping cohorts. Other studies included in the review were animal-model studies (4), biomechanical studies in humans (4), and studies in tactical athletes (3). The nonsport studies were included to inform potential mechanisms of action and biological effects of JVC. This review led to several conclusions. First, animal-model studies support the view that JVC collars increase intracranial pressure and may protect the brain from a single-head traumatic impact; however, the applicability of the animal models to subconcussive repetitive head impact in humans is unknown. Second, biomechanical studies in humans support the ability of JVC collars to increase intracranial pressure and short-term use did not appear to cause harm. Third, studies in athletes show differences in advanced neuroimaging after a season of use between collared and noncollared athletes but no difference in concussion rate or clinically significant difference in neurocognitive testing. The clinical significance of the neuroimaging changes is unclear. Finally, very small studies in tactical athletes (breacher training), which involve blast exposure rather than sport-related impacts, show differences in quantitative EEG, white matter changes, and differences in fMRI between collared and noncollared participants. All studies were funded by the maker of a JVC collar.

Studies in animals (4), biomechanical studies in humans (4), and studies in tactical athletes (3) were included to provide a complete picture of available research. Animal and biomechanical studies suggest JVC increases intracranial pressure providing support for the proposed mechanism of action of the collar. However, the applicability of the single-injury model used in animals to sports-related repetitive subconcussive impacts is unknown. Likewise, forces from blasts experienced by tactical athletes (SWAT) are very different from repetitive subconcussive head impacts experienced by football and soccer athletes, and the ages of the cohorts were different, which can all effect imaging outcomes. Findings from studies on tactical athletes exposed to blast forces may also not be applicable to repetitive head impact in athletes.

The primary finding in 7 of the athlete studies was changes in DTI in the white matter. DTI is an advanced MRI technique that quantifies the directional movement of water molecules in brain tissue, providing sensitive markers of white and grey matter microstructural integrity.⁶ MD refers to the overall magnitude of water diffusion within the brain tissue, AD quantifies diffusion along the axis of white matter tracts and is often associated with axonal integrity, RD measures diffusions perpendicular to axonal fibers and is linked to myelin integrity and fractional anisotropy (FA) reflects the degree of directionality of diffusion with higher values associated with more organized white matter and is reported for different structures in the brain. DTI studies in athletes with concussion generally show that MD, AD, and RD go up and FA goes down after concussion, and are not back to normal when symptoms have resolved and athletes have been cleared to play. Studies of contact athletes after a season of repetitive head impact have conflicting findings.³² There is wide variability among studies, which may be due to acquisition parameters, age of athlete, time postconcussion when imaging is acquired, and wide variability in methods of analysis and interpretation making comparison and generalizations difficult.¹⁷ All of the DTI studies on athletes without a JVC collar compared with athletes wearing the collar for a season reported some changes in white matter DTI parameters; however, the magnitude and direction of change was not always consistent and the clinical significance is unknown.

The other studies in athletes looked at fMRI, resting state fMRI, and neurocognitive testing comparing collared with noncollared athletes. There were no performance differences between groups on neurocognitive tests; however, fMRI BOLD signal response during the working memory task had greater increase in some brain areas in the noncollared group in 2 studies,^41,43 and in another study there was significantly increased resting state fMRI-derived global clustering coefficients and DTI-derived modularity.¹¹ fMRI BOLD is an indirect marker of neural activity potentially indicating more brain activity was required for the task in noncollared athletes and changes in global clustering coefficients and DTI-derived modularity may represent either adaptive reorganization or maladaptive loss of global integration.¹² In addition, 1 study found no differences in male high school football players in a variety of neurocognitive measures.²⁴ These studies indicate that there are no clinically significant differences in functional neurologic outcomes. The clinical significance of advanced MRI changes is unknown.

While commercial JVC collars are FDA approved and marketed to reduce the effects of repetitive head impact, media and athlete testimonials portray a decrease in concussion rate that is not supported in the literature.^26,27 Only 1 study reported on concussion rate and it showed no significant difference between athletes who wore a JVC collar and those who did not.⁴⁰ This latter study was large, with 488 total athletes participating. DTI changes in 20 athletes who sustained a concussion and were not collared were more prominent than in the 20 athletes who sustained a concussion wearing a collar.⁴⁰ There are no studies comparing athletes in noncontact sports wearing collars with those without to assess whether similar differences in DTI exist secondary to collar wearing outside the setting of repetitive impact and the long-term effect of JVC collar use is untested. Finally, these studies were all relatively short-term, following athletes from preseason to postseason with a maximum follow-up 9 months postseason; therefore, potential long-term protection is speculative.

Limitations

This scoping review explores the potential of JVC collar use to mitigate the effects of repetitive head contacts in sports; it is constrained by the limited number of studies in athletes, and the studies appeared to use similar cohorts. Studies in animals and on the biomechanics in humans were included to assess the reasonableness of the proposed mechanism of action. There were no studies comparing the use of a JVC collar with noncollar wearers in noncontact sport that would offer additional insight. Most studies were conducted over a short duration, focusing only on athletes within a single sporting season. All studies involving athletes were funded by Q30 Innovation LLC - the manufacturer of the JVC collar - which raises the possibility of study bias, and all were conducted in North America, potentially limiting generalizability. The review included only studies published in English, which may have led to the omission of relevant research.

Finally, there have been concerns expressed in the literature about inconsistency and errors in the statistical interpretation of some studies,³¹ and 6 studies published in the Journal of Neurotrauma are currently under investigation.^{1,24,29,38,40,41,43} Statistical corrections have been submitted for 3 of the articles, with the authors stating that the corrections do not alter the primary findings or conclusions.^38,40,43 As of October 24, 2025, there have been no findings of wrongdoing.¹ Despite these limitations, this review offers valuable insights into the possible role of JVC in countering the effects of head impacts and identifies key areas for future research.

Conclusion

The findings from this scoping review underscore the need for additional independent research on JVC as an intervention for mitigating the effects of repetitive head impacts during sports-related activities. Animal and human studies suggest that intracranial pressure is increased with JVC compression. Yet, the available evidence in athletes does not demonstrate a reduction in concussion rate or consistent, clinically meaningful improvements in neurocognitive performance associated with JVC collar use. Although several studies report differences in advanced neuroimaging metrics between collared and noncollared athletes following a season of play, the direction and magnitude of these changes are inconsistent, and their clinical significance remains unclear. Furthermore, the studies were all relatively short-term, with a maximum follow-up of 9 months postseason. Therefore, no long-term conclusions can be drawn regarding the use of these devices.

Evidence in animals and tactical personnel provides insight into potential mechanisms of action but involves injury mechanisms and populations that differ substantially from sport-related repetitive head impact. Therefore, findings from animal and military studies may not be directly applicable to sport-related repetitive head impacts in athletes.

Future research is necessary to better understand whether the JVC is protective, especially through large-scale, randomized, long-term studies involving diverse populations and standardized outcome measures as well as studies in noncontact athletes. Until such evidence is available, thoughtful consideration of the body of evidence should be employed before the decision to use or recommend a JVC. Multidisciplinary approaches involving the traditional approach of rule changes, protective equipment, training strategies, and education remain essential in addressing both the short- and long-term consequences of repetitive head impacts in sports, while additional mitigation strategies continue to be explored.

Supplemental Material

sj-docx-1-sph-10.1177_19417381261453672 – Supplemental material for Jugular Venous Compression Collar for Prevention of Brain Injury due to Repetitive Head Impact and Concussion in Sport: A Scoping Review

Supplemental material, sj-docx-1-sph-10.1177_19417381261453672 for Jugular Venous Compression Collar for Prevention of Brain Injury due to Repetitive Head Impact and Concussion in Sport: A Scoping Review by Isabella Weber, Bridget M. Whelan, Jared M. Bruce and Kimberly G. Harmon in Sports Health

Footnotes

Acknowledgements

The authors would like to thank Teresa Jewell, librarian at the University of Washington, for her assistance with the search strategy for this study.

K.G.H. is employed as the Deputy Chief Medical Officer for the National Hockey League (NHL). J.M.B. is co-chair of the NHL concussion subcommittee and director of neuropsychology and neurobehavioral sciences at the NHL. The views and opinions expressed are soley those of the authors and do not necessarily represent those of the NHL. J.M.B. is also the neuropsychology consultant to Sporting KC. The other authors report no potential conflicts of interest in the development and publication of this article.

Protocol registration

Open Science Framework GUID: N8dej

ORCID iDs

Isabella Weber

Bridget M. Whelan

Jared M. Bruce

Kimberly G. Harmon

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