Research Review By Dr. Brynne Stainsby©

Audio:

Date Posted:

Study Title:

Author:

Author's Affiliations:

Publication Information:

Background Information:

Summary:

• Step 1 - Recognize red flags: weakness or tingling/burning in the arms/legs, severe or increasing headache, seizure or convulsions, deteriorating mental status. If present, it is recommended an ambulance is called (19).
• Step 2 - If no red flags are present, look for signs that suggest a concussion has occurred: balance difficulties, blank stare, slow to get up, disorientation, etc. (19).
• Step 3 – Report of symptoms that may occur following concussion (19).
• Step 4 (for athletes over the age of 12) – Five questions related to the sport event (inability to answer correctly may suggest concussion) (19).
• The athlete/parent should be advised that the athlete is not to be left alone for the initial few hours, to avoid alcohol, recreational drugs and driving (19).
• This tool is available HERE (19).

• The SCAT5 and Child SCAT5 are screening tools for healthcare providers, to be used on the sideline or in acute assessment settings. These tools may be used as a part of a multifaceted assessment, but should not replace a thorough clinical exam (20).
• The SCAT 5 is comprised of subgroups of tests for immediate (screening for red flags, recording of observed signs, the Glasgow Coma Scale and Maddocks questions and a cervical spine screen) and office assessment portions (history, symptom report, cognitive assessment, neurological screen and balance assessment) (18, 20).
• The Child SCAT5 includes both parent and child symptom report, neck pain rating, and a photograph for children to describe if they are not able to read (20).

• The Vestibular/Ocular Motor Screen (VOMS) is a brief screen that asks patients to report symptom changes related to headache, dizziness, nausea and fogginess during five tests: smooth pursuit, horizontal and vertical saccades, near point of convergence distance (NPC), horizontal vestibular ocular reflex and visual motion sensitivity (23).
• The VOMS has been shown to be able to screen for concussion at the time of clinical follow-up (5.5 days +/- 4.0 days following concussion; range 1-21 days) (23).
• Signs and symptoms on VOMS can be used to suggest concussion, but should not replace a multifaceted clinical examination.

• Up to 30% of children and youth may have ongoing symptoms four weeks following injury (8, 24). Those with high symptom intensity in the acute period, vestibulo-ocular dysfunction and cervical spine involvement may take longer to recover (25-27).
• In most cases, patients have a number of persistent symptoms and a comprehensive evaluation for these patients should include a history, neurological evaluation, assessment of the cervical spine, balance, vestibulo-ocular and visual function, mood and neurocognitive screening (13, 28, 29).
• A thorough history and physical examination can then be used to determine management.

• Headache (HA) is one of the most common symptoms following concussion, affecting 40-86% of patients with a concussion (16, 30). Posttraumatic HA (by definition) occurs within seven days of the concussion (31) and may be associated with dizziness or balance deficits (32, 33).
• Persistent posttraumatic HA may be reported as migraine or probable migraine, tension-type HA, cervicogenic HA, occipital neuralgia or medication overuse HA depending on the symptomatology (30, 31, 34, 35).

• Neck pain (NP) is common following concussion, and it is possible that the trauma which caused the concussion may have also injured the neck (36, 37). Many symptoms are similar to those reported by those who have suffered a whiplash injury (38-40).
• The upper C/S has a proprioceptive role and alterations in cervical afferent inputs may result in cervicogenic dizziness (41-43).
• The myofascial system may be a source of HA or NP (44). Trigger points may be reported in the paraspinal and cervical muscles.
• A C/S exam should include range of motion and palpation for segmental tenderness to detect facet joint dysfunction (45-47).
• The cervical flexion rotation test has also been reported to have good diagnostic accuracy for C1-2-related cervicogenic HA (48,49).
• Assessment of the deep cervical flexor muscles can be performed with the craniocervical flexion test (50). Individuals with NP have altered neuromotor control strategies (51-53).
• The cervical flexor endurance test has been shown to be a useful test in distinguishing patients with whiplash associated disorders from healthy controls and may also be useful in patients with persistent concussion symptoms. The cervical extensor endurance and cervical rotation side-flexion test can also be used to assess the strength of the cervical musculature.
• Assessment of sensorimotor control of the C/S can include the joint position error (the ability to relocate the head to a neutral position in space) (54), trunk relocation with stationary head (55), smooth pursuit neck torsion test (56), cervical torsion test (57) and/or the head perturbation test (29). Future research is required to understand the clinical utility of these tests (as well as the best combination to use) in concussion (58, 59).
• One exploratory cohort study in youth ice hockey players compared a series of C/S measurements pre and post-concussion (29). In the acute post-injury period, 58% of subjects reported an increase in HA and 42% reported an increase in NP (29). Following injury, the concussion cohort performed significantly worse on measures of C/S function (29).

• Dizziness is a common symptom following concussion (60) and must be evaluated to rule out severe injury such as ischemic stroke (61-63). Careful differential diagnosis to identify the underlying cause is important as some are best treated medically, while others are amenable to vestibular rehabilitation (64-67). Afferent information from the proprioceptive, visual and vestibular receptors provide input regarding spatial location, and if one or more of these systems provides inaccurate information, alterations in balance/dizziness may result (68-70).
• It is important to inquire about the nature of the dizziness (vertigo, disequilibrium, pre-syncope), duration, aggravating and relieving factors, and concurrent symptoms.
• A variety of vestibular disorders may occur, including benign paroxysmal positional vertigo, labyrinthine concussion, otolith dysfunction, post-traumatic endolymphatic hydrops, post-traumatic migraine, brainstem or vestibulocerebellar dysfunction, cervicogenic dizziness and psychogenic dizziness (64-66, 68, 71-73).
• Individuals may also present with findings of peripheral vestibular hypofunction (74). Initially, patients present with vertigo and unsteadiness, and as they recover, symptoms change to dizziness or lightheadedness. They may additionally present with nystagmus, alterations in vestibulo-ocular reflex, static and dynamic balance deficits and sensitivity to motion (75).
• Cervicogenic dizziness is described as an imbalance or feeling of disequilibrium occurring with NP, stiffness or HA (77). It is believed to be caused by a dysfunction in the upper C/S, causing an alteration in cervical afferent input (77).
• The clinical presentation of dizziness may change with recovery as function increases and ongoing reassessment is required to understand the source of dizziness and identify appropriate treatments (65). Clinicians should be encouraged to collaborate with those who have expertise in vestibular assessment and rehabilitation.
• Standing and dynamic balance may also be altered following concussion (66, 78). The Balance Error Scoring System (BESS) is a clinical test with demonstrated reliability in collegiate athletes that evaluates postural sway (70, 79). Changes in gait parameters may also occur following concussion, such as tandem gait speed, which has been reported to be significantly slower in collegiate athletes acutely following concussion (80).

• Individuals may report difficulty with dividing attention between movement or balance and a cognitive task following concussion (81, 82). A cohort study demonstrated improvements in time to compete a task of divided attention in youth ice hockey players during recovery following concussion (29).
• Visual complaints such as double or blurred vision, difficulty reading or eye fatigue may be reported following a concussion (83-85). Convergence difficulties and accommodation disorders are the most common visual disturbances reported (85-88). Individuals may have difficulty completing visual tasks, and could be tested using the VOMS or King-Devick test (89). Referral to an optometrist, neuro-optometrist or ophthalmologist may be warranted in some cases.
• Individuals with persistent symptoms may have difficulties with exertion, which may be demonstrated with symptom provocation during activity or intolerance to exercise (90-92). Both physical and cognitive exertional testing may be performed; however, clinicians should note that no valid measure of cognitive exertion exists. In adults, the Buffalo Concussion Treadmill Test (93) is a commonly used test of physical exertion, and the test is stopped at the onset of symptoms. It is also important that prior to physical exertion testing, clinicians carefully consider patient’s presentation and ensure safety (94, 95).
• Up to 50% of collegiate athletes may report difficulty with concentration and memory following a concussion (though most report resolution within 10 days) (17, 96). A neuropsychology evaluation can assist with the underlying source of cognitive symptoms. As there is limited evidence to support cognitive interventions (97), if there are ongoing difficulties with cognitive function, referral to a neuropsychologist may be warranted (98).
• A small number of athletes report feeling irritable or sad following a concussion, and typically, these symptoms resolve within the first week (17). Concussion can trigger mental health disorders however, and in patients with pre-existing anxiety or depression, recovery may be prolonged (27). Emotional symptoms tend to present later in the recovery period, and thus it is important to recognize concurrent mental health concerns and refer the patient to his/her physician, or a psychologist, psychiatrist or neuropsychologist for appropriate management.
• Up to 20% of high school and collegiate athletes have reported difficulties with sleep following concussion (17). Assessing sleep is very important as poor sleep has been associated with poor health outcomes (99, 100). Poor sleep quality may be secondary to pain, and thus sleep posture should be assessed and modified if possible. It has also been hypothesized that autonomic dysfunction may contribute to sleep difficulties (101). Following mild traumatic brain injury, insomnia has been associated with higher levels of disability and pain, and poor sleep quality predicted poorer mood, cognitive ability, and post-concussion symptoms one year following concussion (102, 103). If ongoing sleep difficulties persist, referral to a physician with expertise in sleep management may be warranted.

Clinical Application & Conclusions:

Study Methods:

Study Strengths / Weaknesses:

• This review provides a thorough overview of the symptoms which may present in the immediate post-concussion period, as well as symptoms which may persist.
• It also highlights the need to recognize, remove and re-evaluate athletes if concussion is suspected.
• A variety of tests which can be used to screen for concussion and test for post-concussion symptoms were presented.
• Common clinical screening tools (SCAT5 and Child SCAT5) which can be used to assess patients were also summarized.

• The primary limitation of this paper is the lack of a description of the methods employed.
• The author does not include statements regarding the research question, search strategy or if/how the quality of the included evidence was appraised.
• Although a number of tests are presented in this review, the psychometric properties are not discussed, and clinicians should interpret them with caution pending further research in concussion populations (the author did mention this when appropriate).

Additional References:

1. Emery C, Meeuwisse W. Injury rates, risk factors, and mechanisms of injury in minor hockey. Am J Sports Med 2006; 34: 1960–1969.
2. Zuckerman SL, Kerr ZY, Yengo-Kahn A et al. Epidemiology of sports-related concussion in NCAA athletes fro 2009-2010 to 2013-2014 incidence, recurrence and mechanisms. Am J Sports Med 2015; 43: 2654–2662.
3. Emery C, Black AM, Kolstad A et al. What strategies can be used to effectively reduce the risk of concussion in sport? A systematic review. BJSM 2017; 51: 978–984.
4. Emery C, Meeuwisse W, McAllister J. Survey of sport participation and sport injury in Calgary and area high schools. Clin J Sport Med 2006; 16: 20–26.
5. Emery C, Tyreman H. Sport participation, sport injury, risk factors and sport safety practices in Calgary and area junior high schools. Paediatr Child Health 2009; 14: 439–444.
6. Kerr Z, Cortes N, Caswell A et al. Concussion rates in United States middle school athletes, 2015/2016 school year. Am J Prev Med 2017; 53(6): 914–918.
7. O'Connor KL, Baker MM, Dalton SL et al. Epidemiology of sport-related concussion in high school athletes: national athletic treatment, injury and outcomes network (NATION), 2011-2012 through 2013-2014. J Athl Train 2017; 52: 175–185.
8. Schneider K, Nettel-Aguirre A, Palacios-Derfingher L et al. Concussion Burden, Recovery and Risk Factors in Elite Youth Ice Hockey Players. CJSM ePub 2018b.
9. Feigin VL, Theadom A, Barker-Collo S et al. Incidence of traumatic brain injury in New Zealand: a population-based study. Lancet Neurol 2013; 12: 53–64.
10. Langlois JA, Rutland-Brown W, Wald MM. The epidemiology and impact of traumatic brain injury: a brief overview. J. Head Trauma Rehabil 2006; 21: 375–378.
11. McCrory P, Feddermann-Demont N, Dvorak J et al. What is the definition of sports-related concussion: a systematic review. BJSM 2017; 51: 877–887.
12. McCrory P, Meeuwisse W, Dvorak J et al. Consensus statement on concussion in sport - the 5th international conference on concussion in sport held in Berlin, October 2016. BJSM 2017; 51: 838–847.
13. Feddermann-Demont N, Echemendia RJ, Schneider KJ et al. What domains of clinical function should be assessed after sport-related concussion? A systematic review. Br J Sports Med 2017; 51: 903–918.
14. Patricios J, Fuller GW, Ellenbogen RG et al. What are the critical elements of sideline screening that can be used to establish the diagnosis of concussion? A systematic review. BJSM 2017; 51: 888–894.
15. Schneider K. Sport-related concussion: optimizing treatment through evidence-informed practice. JOSPT 2016; 46: 613–616.
16. Kerr ZY, Zuckerman SL, Wassermann EB et al. Concussion symptoms and return to play time in youth, high school and college American football athletes. JAMA Pediatr 2016; 170: 647–653.
17. Marshall SW, Guskiewicz K, Shankar V. Epidemiology of sports-related concussion in seven US high school and collegiate sports. Injury Epidemiol 2015; 2: 13.
18. Echemendia RJ, Meeuwisse W, McCrory P et al. The concussion recognition tool 5th edition (CRT5): background and rationale. BJSM 2017c; 51: 870–871.
19. Echemendia RJ, Meeuwisse W, McCrory P et al. The sport concussion assessment tool 5th edition (SCAT5). BJSM 2017b; 51: 848–850.
20. Stiell IG, Wells GA, Vandemheen KL et al. The Canadian C-Spine rule for radiography in alert and stable trauma patients. J. Am. Med. Assoc 200a; 286: 1841–1848.
21. Stiell IG, Wells GA, Vandemheen KL et al. The Canadian CT Head Rule for patients with minor head injury. Lancet 2001b; 357: 1391–1396.
22. Mucha A, Collins MW, Elbin RJ et al. A brief vestibular/ocular motor screening (VOMS) assessment to evaluate concussions. Preliminary findings. Am J Sports Med 2014; 42: 2479–2486.
23. Zemek R, Barrowman N, Freedman SB et al. Clinical risk score for persistent postconcussion symptoms among children with acute concussion in the ED. J Am Med Assoc 2016; 315: 1014–1025.
24. Ellis MJ, Cordingley D, Vis S et al. Vestibuloocular dysfunction in pediatric sports-related concussion. J. Neurosurg. Pediatr 2015; 16: 248–256.
25. Ellis MJ, McDonald PJ, Olson A et al. Cervical spine dysfunction following pediatric sports-related head trauma. J. Head Trauma Rehabil 2019; 34(2): 103–110.
26. Iverson G, Gardner A, Terry D et al. Predictors of clinical recovery from concussion: a systematic review. BJSM 2017; 51: 941–948.
27. Broglio SP, Macciocchi SN, Ferrara MS. Sensitivity of the concussion assessment battery. Neurosurgery 2007; 60: 1050–1058.
28. Schneider K, Meeuwisse W, Palacios-Derfingher L et al. Changes in measures of cervical spine, vetibulo-ocular reflex, dynamic balance and divided attention following sport-related concussion in elite youth ice hockey players. JOSPT 2018a; 48: 974–981.
29. Lucas S, Hoffman JM, Bell KR et al. A prospective study of prevalence and characterization of headache following mild traumatic brain injury. Cephalalgia: Int J Headache 2014; 34: 93–102.
30. Lucas S. Posttraumatic headache: clinical characterization and management. Curr Pain Headache Rep 2015; 19(10): 48.
31. Necajauskaite O, Endziniene M, Jurieniene K. Prevalence, clinical features and accompanying signs of post-traumatic headache in children. Medicina (Kaunas) 2005; 41: 100–108.
32. Register-Mihalik J, Mihalik JP, Guskiewicz K. Balance deficits after sportsrelated concussion in individuals reporting posttraumatic headache. Neurosurgery 2008; 63: 76–82.
33. Pinchefsky E, Dubrovsky AS, Friedman D et al. Part I - evaluation of pediatric post-traumatic headaches. Pediatr Neurol 2015; 52: 263–269.
34. Zasler ND. Sports concussion headache. Brain Inj 2015; 29: 207–220.
35. Benson BW, Meeuwisse WH, Rizos J et al. A prospective study of concussions among National Hockey League players during regular season games: the NHL-NHLPA Concussion Program. Can Med Assoc J 2011; 183: 905–911.
36. MacGregor K, Atkins C, Blake TA et al. Clinical characteristics, referral patterns and time to recovery in youth and adults following a sport-related concussion. BJSM 2017; 51: E126.
37. Elkin BS, Elliott JM, Siegmund GP. Whiplash injury or concussion? A possible biomechanical explanation for concussion symptoms in some individuals following a rear-end collision. JOSPT 2016; 46: 874–885.
38. Hynes LM, Dickey J. Is there a relationship between whiplash-associated disorders and concussion in hockey? A preliminary study. Brain Inj 2006; 20: 179-188.
39. Morin M, Langevin P, Fait P. Cervical spine involvement in mild traumatic brain injury: a review. J Sport Med 2016; https://doi.org/10.1155/2016/1590161
40. Kristjansson E, Treleaven J. Sensorimotor function and dizziness in neck pain: implications for assessment and management. J Orthop Sport Phys Ther 2009; 39: 364–377.
41. Treleaven J, LowChoy N, Darnell R et al. Comparison of sensorimotor disturbance between subjects with persistent whiplash-associated disorder and subjects with vestibular pathology associated with acoustic neuroma. Arch Phys Med Rehabil 2008; 89: 522–530.
42. Treleaven J, Peterson G, Landen-Lundvigsson M et al. Balance, dizziness and proprioception in patients with chronic whiplash associated disorders complaining of dizziness: a prospective randomized study comparing three exercise programs. Man Ther 2016; 22: 122–130.
43. Lluch E, De Kooning M, Van Dyck D et al. Prevalence, incidence, localization and pathophysiology of myofascial trigger points in patients with spinal pain: a systematic literature review. J Manip Physiol Ther 2015; 38: 587–600.
44. Jull G, Bogduk N, Marsland A. The accuracy of manual diagnosis for cervical zygapophysial joint pain syndromes. Med J Aust 1998; 148: 233.
45. Schneider G, Jull G, Thomas K et al. Intrarater and interrater reliability of select clinical test in patients referred for diagnostic facet joint blocks in the cervical spine. Arch Phys Med Rehabil 2013; 94: 1628–1634.
46. Schneider GM, Jull G, Thomas K et al. Derivation of a clinical decision guide in the diagnosis of cervical facet joint pain. Arch Phys Med Rehabil 2014a; 95: 1695–1701.
47. Hall T, Robinson K. The flexion-rotation test and active cervical mobility – a comparative measurement study in cervicogenic headache. Man. Ther 2004; 9: 197–202.
48. Ogince M, Hall T, Robinson K et al. The diagnostic validity of the cervical flexion-rotation test in C1-C2 related cervicogenic headache. Man Ther 2007; 12, 256–262.
49. Jull G, Barrett C, Magee R et al. Further clinical clarification of the muscle dysfunction in cervical headache. Cephalalgia 1999; 19: 179–185.
50. Jull G, Sterling M, Kenardy J et al. Does the presense of sensory hypersensitivity influence outcomes of physical rehabilitation for chronic whiplash? Prelimin RCT. Pain 2007; 129: 28–34.
51. Chen X, Treleaven J. The effect of neck torsion on joint position error in subjects with chronic neck pain. Man. Ther 2013; 18: 562–567.
52. Tjell C, Rosenhall U. Smooth pursuit neck torsion test: a specific test for cervical dizziness. Am J Otol 1998; 19: 76–81.
53. L'Heureux-Lebeau B, Godbout A, Berbiche et al. Evaluation of paraclinical tests in the diagnosis of cervicogenic dizziness. Otol Neurotol 2014; 35: 1858–1865.
54. Cheever K, Kawata K, Tierney R et al. Cervical injury assessments for concussion evaluation: a review. J Athl Train 2016; 51: 1037–1044.
55. Treleaven J. Dizziness, unsteadiness, visual disturbances and sensorimotor control in traumatic neck pain. JOSPT 2017; 47: 492–502.
56. Schneider KJ, Meeuwisse WH, Nettel-Aguirre A et al. Cervicovestibular physiotherapy in the treatment of individuals with persistent symptoms following sport related concussion: a randomised controlled trial. Br J Sports Med 2014b; 48: 1294–1298.
57. Choi JH, Park MG, Choi SY et al. Acute transient vestibular syndrome: prevalence of stroke and efficacy of bedside evaluation. Stroke 2017; 48: 556–562.
58. Kattah JC, Talkad AV, Wang DZ et al. HINTS to diagnose stroke in the acute vestibular syndrome: three-step bedside oculomotor examination more sensitive than early MRI diffusion-weighted imaging. Stroke 2009; 40: 3504–3510.
59. Merwick A, Werring D. Posterior circulation ischaemic stroke. BMJ 2014; 1–11.
60. Alsalaheen BA, Mucha A, Morris LO et al. Vestibular rehabilitation for dizziness and balance disorders after concussion. J Neurol Phys Ther 2010b; 34: 87–93.
61. Ernst A, Basta D, Seidl RO et al. Management of posttraumatic vertigo. Otolaryngol Head Neck Surg 2005; 132: 554–558.
62. Gottshall K, Drake A, Gray N et al. Objective vestibular tests as outcome measures in head injury patients. The Laryngoscope 2003; 113: 1746–1750.
63. van Leeuwen RB, van der Zaag-Loonen H. Dizziness and neck pain: a correct diagnosis is required before consulting a physiotherapist. Acta Neurol. Belg 2017; 117: 241–244.
64. Herdman S. Vestibular Rehabilitation, third ed. F.A. Davis Company, Philadelphia, PA 2007.
65. Guskiewicz K, Ross S, Marshall S. Postural stability and neuropsychological deficits after concussion in collegiate athletes. J Athl Train 2001; 36: 263–273.
66. Balatsouras DG, Koukoutsis G, Aspris A et al. Benign paroxysmal positional vertigo secondary to mild head trauma. Ann Otol Rhinol Laryngol 2017; 126: 54–60.
67. Ellis MJ, Cordingley D, Vis S et al. Vestibuloocular dysfunction in pediatric sports-related concussion. J. Neurosurg. Pediatr 2015; 16: 248–256.
68. Hoffer ME, Gottshall KR, Moore R et al. Characterizing and treating dizziness after mild head trauma. Otol Neurotol Off Publ Am Otol Soc Am Neurotol Soc Eur Acad Otol Neurotol 2004; 25: 135–138.
69. Zhou G, Brodsky JR. Objective vestibular testing of children with dizziness and balance complaints following sports-related concussions. Otolaryngol. Head Neck Surg 2015; 152: 1133–1139.
70. Maskell F, Chiarelli P, Isles R. Dizziness after traumatic brain injury: overview and measurement in the clinical setting. Brain Inj 2006; 20: 293–305.
71. Schubert M, Minot LB. Vestibulo-ocular physiology underlying vestibular hypofunction. Phys Ther 2004; 84: 373–385.
72. Hong T, Scurfield A, Schneider K et al. Vestibular dysfunction following paediatric trainmatic brain injury - prevalence and exploration of a novel diagnostic tool. Brain Inj 2014; 28: 839.
73. Reid S, Rivett DA, Katekar MD et al. Sustained natural apophyseal glides (SNAGs) are an effective treatment for cervicogenic dizziness. Man Ther 2007; 13: 357–366.
74. Guskiewicz KM. Assessment of postural stability following sport-related concussion. Curr Sports Med Rep 2003; 24–30.
75. Riemann B, Guskiewicz KM, Shields, E. Relationship between clinical and force plate measures of postural stability. J Sport Rehabil 1999; 8: 71–82.
76. Oldham JR, Difabio MS, Kaminski TW et al. Efficacy of tandem gait to identify impaired postural control after concussion. Med Sci Sport Exerc 2018; 50: 1162–1168.
77. Parker T, Osternig L, Lee H et al. The effect of divided attention on gait stability following concussion. Clin. Biomech 2005; 20: 389–395.
78. Bogduk N, Marsland A. On the concept of third occipital headache. J Neurol Neurosurg Psychiatry 1986; 49: 775–780.
79. Capo-Aponte J, Urosevich T, Temme L et al. Visual dysfunctions and symptoms during the subacute stage of blast-induced mild traumatic brain injury. Mil Med 2012; 177: 804–813.
80. Laukkanen HMS, Hayes J. Brain injury symptom survey (BIVSS) questionnaire. Optom Vis Sci 2017; 94: 43–50.
81. Master CL, Scheiman M, Gallaway M et al. Vision diagnoses are common after concussion in adolescents. Clin Pediatr 2016; 55: 260–267.
82. Master C, Master S, Wiebe D et al. Vision and vestibular system dysfunction predicts prolonged concussion recovery in children. CJSM 2018; 28: 139–145.
83. Mucha A, Collins MW, Elbin RJ et al. A brief vestibular/ocular motor screening (VOMS) assessment to evaluate concussions. Preliminary findings. Am J Sports Med 2014; 42: 2479–2486.
84. Ventura R, Balcer L, Galetta S. The Concussion Toolbox: the role of vision in the assessment of concussion. Semin Neurol 2015; 35: 599–606.
85. King D, Hume P, Gissane C et al. Use of the King-Devick test for sideline concussion screening in junior rugby league. J Neurol Sci 2015; 357: 75–79.
86. Leddy JJ, Cox JL, Baker JG et al. Exercise treatment for postconcussion syndrome: a pilot study of changes in functional magnetic resonance imaging activation, physiology, and symptoms. J Head Trauma Rehabil 2013a; 28: 241–249.
87. Leddy JJ, Baker JG, Merchant A et al. Brain or strain? Symptoms alone do not distinguish physiologic concussion from cervical/vestibular injury. Clin J Sport Med 2015; 25: 237–242.
88. Leddy JJ, Kozlowski K, Donnelly JP et al. A preliminary study of subsymptom threshold exercise training for refractory postconcussion syndrome. Clin J Sport Med 2010; 20: 21–27.
89. Leddy JJ, Baker JG, Kozlowski K et al. Reliability of a graded exercise test for assessing recovery from concussion. Clin J Sport Med 2011; 21: 89–94.
90. Gagnon I, Grilli L, Friedman D et al. A pilot study of active rehabilitation for adolescents who are slow to recover from sport-related concussion. Scand J Med Sci Sports 2016a; 26: 299–306.
91. Leddy, JJ, Facp F, Willer B. Use of Graded Exercise Testing in Concussion and Return-To-Activity Management, vol. 12, 2013b.
92. McCrea M, Guskiewicz KM, Marshall SW et al. Acute effects and recovery time following concussion in collegiate football players: the NCAA concussion study. J Am Med Assoc 2003; 290: 2556–2563.
93. Robinson KE, Kaizar E, Catroppa C et al. Systematic review and meta-analysis of cognitive interventions for children with central nervous system disorders and neurodevelopmental disorders. J Pediatr Psychol 2014; 39: 846–865.
94. Foundation OON. Guidelines for Concussion/mTBI & Persistent Symptoms, third ed. Ontario Neurotrauma Foundation 2018.
95. Daley M, Morin CM, LeBlanc M. Insomnia and its relationship to health care utilization, work absenteeism, productivity and accidents. Sleep Med 2009; 10: 427–438.
96. Grandner MA, Jackson NJ, Pak VM. Sleep disturbance is associated with cardiovascular and metabolic disorders. J. Sleep Res 2012; 21: 427–433.
97. Leddy J, Baker JG, Haider MN et al. A physiological approach to prolonged recovery from sport-related concussion. J Athl Train 2017; 52: 299–308.
98. Mollayeva T, Prett B, Mollayeva S et al. The relationship between insomnia and disability in workers with mild traumatic brain injury/concussion insomnia and disability in chronic mild traumatic brain injury. Sleep Med 2016; 20: 157–166.
99. Theadom A, Cropley M, Parmar P et al. Sleep difficulties one year following mild traumatic brain injury in a population-based study. Sleep Med 2015; 16: 926–932.