Cervical spinal motion restriction was defined as the reduction or limitation of cervical spinal movement. This definition may not be consistent with definitions used in some countries or by some organizations. Spinal stabilization was defined as the physical maintenance of the spine in a neutral position before applying spinal motion restriction devices. This evaluation was limited to mechanical cervical immobilization devices accessible to first aid providers, including cervical collars and sandbags with tape, but did not include spine boards. Semi)rigid Collar (I) Compared With No Collar (C) For the critical outcome of neurologic injury, we identified very-low-quality evidence (downgraded for risk of bias and imprecision) from 1 nonrandomized study(Lin 2011, 1028) with 5138 motorcycle crash victims, showing no difference in neurologic injury (no significant difference according to the article; however, we were unable to calculate the MD and CI, because the mean and standard deviation (SD) of the intervention and control group were not reported). For the critical outcome of complications (intracranial pressure), we identified low-quality evidence from 5 nonrandomized studies(Raphael 1994, 437; Davies 1996, 647; Kolb 1999, 135; Hunt 2001, 511; Mobbs 2002, 389) with 107 patients in total, showing increased intracranial pressure with the use of a cervical collar (MD [mm Hg], 4.69; 95% CI, 1.95–7.43; MD [mm H20], 20.48; 95% CI, 5.62–35.33). We also identified very-low-quality evidence (downgraded for indirectness) from 1 nonrandomized study(Stone 2010, 100-102) with 42 healthy volunteers showing increased intracranial pressure (MD [internal jugular vein cross-sectional area], 0.19; 95% CI, 0.05–0.33) with the application of a cervical collar. For the critical outcome of complications (tidal volume), we identified very-low-quality evidence (downgraded for risk of bias and imprecision) from 1 nonrandomized study(Dodd 1995, 961) with 38 patients, showing no decrease in tidal volume (a significant decrease was reported in the publication; however, we were unable to calculate the CI because the SD of the intervention and control group was not reported). For the important outcome of cervical spine movement, we identified low-quality evidence from 1 nonrandomized study(Treloar 1997, 5) with 18 head-injured children showing no significant limitation of flexion (MD, −2.20; 95% CI, −7.75 to 3.35). For the same outcome, we also identified very-low-quality evidence (downgraded for indirectness) from 13 nonrandomized studies(Fisher 1977, 109; Podolsky 1983, 461; Rosen 1992, 1189; Sandler 1996, 1624; Hughes 1998, 374; Bednar 2004, 251; Del Rossi 2004, 619; Zhang 2005, 264; Tescher 2007, 1120; DiPaola 2008, 273; Conrad 2010, 432; Horodyski 2011, 513; Evans 2013, S10) with 457 cadavers or healthy volunteers showing significant decrease in flexion, extension, lateral bending, axial rotation, and flexion/extension (flexion: MD, −12.50; 95% CI, −13.13 to −11.87; extension: MD, −0.91; 95% CI, −1.18 to −0.64; lateral bending: MD, −1.99; 95% CI, −2.33 to −1.65; axial rotation: MD, −4.73; 95% CI, −5.16 to −4.3; flexion/extension: MD, −19.13; 95% CI, −19.89 to −18.36]). Seven additional studies(Cline 1985, 649; Burl 1991, 308; Hamilton 1996, 553; Askins 1997, 1193; Richter 2001, 848; Gavin 2003, 527; Ben-Galim 2010, 447) were not included in the final analysis because they were missing data (mean and/or SD of intervention and control group not reported). For the important outcome of patient comfort, we identified very-low-quality evidence (downgraded for indirectness and imprecision) from 1 nonrandomized study(Hamilton 1996, 553) with 26 healthy volunteers, showing no change in patient comfort score. We did not identify any evidence to address the important outcomes of overall mortality and pain and the less important outcome of hospital length of stay. Soft Collar (I) Compared With No Collar (C) For the important outcome of cervical spine movement, we identified very-low-quality evidence (downgraded for indirectness) from 3 nonrandomized studies(Podolsky 1983, 461; Sandler 1996, 1624; Bednar 2004, 251) with 36 cadavers or healthy volunteers showing a significant decrease in flexion and axial rotation (flexion: MD, −3.04; 95% CI, −5.64 to −0.4; axial rotation: MD, −9.07; 95% CI, −14.17 to −3.96). The same studies showed no significant difference in terms of limiting extension, flexion/extension, and lateral bending. We did not identify any evidence to address the critical outcomes of neurologic injury and complications; the important outcomes of overall mortality, pain, and patient comfort; and the less important outcome of hospital length of stay. Sand Bags and Tape (I) Compared With No Motion Restriction (C) For the important outcome of cervical spine movement, we identified very-low-quality evidence (downgraded for indirectness) from 1 nonrandomized study(Podolsky 1983, 461) with 25 healthy volunteers showing a significant decrease in flexion, extension, axial rotation, and lateral bending (flexion: MD, −35.60; 95% CI, −38.69 to −32.51; extension: MD, −6; 95% CI, −9.53 to −2.47; axial rotation: MD, −73.30; 95% CI, −75.99 to −70.61; lateral bending: MD, −19.40; 95% CI, −21.62 to −17.18). We did not identify any evidence to address the critical outcomes of neurologic injury and complications; the important outcomes of overall mortality, pain, and patient comfort; and the less important outcome of hospital length of stay.