CHAPTER 36

Sports-Related Concussion

Introduction/Etiology/Epidemiology

• Concussion is also known as mild traumatic brain injury.

• A concussion is a functional brain injury not identifiable with conventional imaging such as magnetic resonance imaging (MRI) or computed tomography (CT). The injury is usually caused by a direct impact to the head or blow to the body that causes a sudden acceleration or deceleration of the head, resulting in one or more physical, cognitive, sleep, or emotional symptoms and signs. These changes in neurologic function are almost always temporary.

• The pathophysiology is not completely understood but is most likely microscopic injury to neuronal cell membranes, which causes alterations in electrolyte levels, glucose utilization, and cerebral blood flow, resulting in an “energy crisis” and impaired brain function.

• An estimated 1.9 million children and adolescents younger than 18 years of age suffer a sports- or recreation-related concussion annually in the United States; however, this is likely an underestimate due to underreporting.

• About 13% of all injuries reported in high school athletes are concussions.

• The 5 highest-risk high school sports (listed in descending order) are American tackle football, girls’ soccer, boys’ lacrosse, boys’ ice hockey, and wrestling.

• There is less research on athletes younger than high school age, but American tackle football, girls’ soccer, cheer, and girls’ basketball appear to carry the highest concussion risk at the middle school level.

• In general, there is a higher concussion rate in competition compared to practices. However, cheer has a higher concussion rate in practice than in competition.

• Girls appear to have higher rates of concussion when compared to boys in the same sport.

• Children and adolescents, when compared with adults, are more susceptible to concussion and have longer recovery times.

• When identified and managed properly, most concussions are not life-threatening and do not result in long-term symptoms or permanent cognitive deficits.

Signs and Symptoms

• Concussion signs and symptoms may be grouped into the following 5 categories:

— Physical or Somatic: headaches, nausea, vomiting, fatigue, light sensitivity, noise sensitivity, numbness/tingling, dizziness, hearing problems (eg, difficulty hearing in noisy environments, tinnitus)

— Vestibular/Oculomotor: balance problems, vision problems (eg, convergence insufficiency)

— Cognitive: confusion, feeling mentally “foggy,” difficulty concentrating, difficulty remembering/forgetfulness, slowed responses, repetitive questions, loss of consciousness (LOC), retrograde amnesia (unable to recall events before the injury), anterograde amnesia (unable to recall events after the injury)

— Emotional: irritability, sadness, more emotional than usual, nervousness/ anxiety, personality changes

— Sleep: fatigue, drowsiness, sleeping too much, sleeping too little, difficulty falling asleep

• Some patients may have only one symptom, but more commonly patients will present with several.

• Symptoms may occur immediately after the impact or not become evident until a few hours later.

• Contrary to popular belief, LOC is not required for the diagnosis of concussion. In fact, LOC is present in less than 5% of concussions.

• Headache occurs 86% to 96% of the time, making it the most common, but not universal, symptom.

• Rarely, seizure-like movements or tonic posturing may be seen immediately after the impact. While these are most often benign motor phenomena associated with a concussion and not necessarily predictive of future seizures or seizure disorders, any seizure-like activity within the first few hours after head impact should prompt immediate transport to a hospital for further evaluation.

Differential Diagnosis

• Epidural hematoma

• Subdural hematoma

• Cerebral contusion or hemorrhage

• Subarachnoid hemorrhage

• Skull fracture

• Arnold-Chiari malformation

• Headache disorder

• Syncope

• Seizure

• Neck pain can be concerning for a cervical spine fracture or spinal cord injury. Any athlete with significant midline neck pain should be treated with cervical spine precautions (immobilization in hard cervical collar on spine board). Other indications for cervical spine precautions include altered consciousness or unconscious athlete, or bilateral neurologic findings or issues.

• Symptoms concerning for a skull fracture or intracranial hemorrhage are listed in Box 36-1.

Box 36-1.Symptoms Concerning for a Skull Fracture or Intracranial Hemorrhage

Diagnostic Considerations

• The diagnosis is established clinically, based on the presence of signs and symptoms after an impact to the head or a blow to the body resulting in an acute acceleration or deceleration of the head.

• Currently, there is no objective diagnostic test that confirms a concussion, although many are being actively researched.

• A Likert scale symptom checklist can be used to quantify initial symptom load and track recovery. Some patients have these symptoms prior to their concussion, so in these cases recovery is determined by return to pre-injury level of symptoms, rather than zero symptoms.

• In some circumstances, the mechanism of injury may be unknown (not seen by anyone or not remembered by the athlete because of amnesia).

• Physical examination

— Should include a neurologic examination, a head-and-neck evaluation, an ocular assessment, balance testing, and an assessment of cognitive function and memory

— Sideline concussion assessment tools, such as the Sport Concussion Assessment Tool, Fifth edition (SCAT5; available at https://bjsm.bmj.com/content/bjsports/early/2017/04/26/bjsports-2017-097506SCAT5.full.pdf) and Child SCAT5 (available at https://bjsm.bmj.com/content/bjsports/early/2017/04/26/bjsports-2017-097492childscat5.full.pdf), provide a concise framework for evaluating a possible concussion. When used in the office setting 3 to 5 days after injury, utility of the balance and cognitive testing components is limited, but the symptom checklist is very helpful.

— Cognitive tests and balance testing are the physical examination components most likely to elicit abnormal findings when a concussion is present.

— However, findings of the physical examination, including the cognitive assessment, may be entirely normal in the setting of a concussion.

• Vestibular/Ocular Motor Screening (VOMS) assessment

— Evaluates the systems that integrate balance, vision, and movement

— Tests for symptoms or deficits with saccades, smooth pursuits, convergence, vestibular ocular reflex, and visual motion sensitivity

— About 70% of children and adolescents with concussion will have visual issues and/or abnormalities on VOMS. Abnormal VOMS may also be a marker for prolonged recovery.

— VOMS can assist in concussion diagnosis and may also be used to identify prolonged difficulties related to vestibular-ocular motor dysfunction, for which a referral to vision or vestibular rehabilitation services may be of benefit. Vestibular and ocular dysfunction can result in difficulties with reading, taking notes, and concentrating, and thus hinder return to school and/or learning.

— For instructions on performing and scoring the VOMS assessment, see the 2014 article by Mucha et al listed in the Part 11 Bibliography (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4209316/).

• Balance testing

— The most commonly used test is the modified Balance Error Scoring System (BESS), a validated tool for assessment of postural stability.

■Instructions for performing the modified BESS are contained in the SCAT5 and Child-SCAT5. The BESS score may be compared to normative data (Table 36-1) and followed through the course of recovery.

— Improvements in balance (lower BESS scores) are generally seen with recovery.

— Tandem gait test is an additional examination to evaluate balance.

• Imaging

— Neuroimaging is not required for diagnosis of concussion. Concussion is not visualized by standard neuroimaging, CT, or MRI. Imaging is only indicated if there are concerns for fracture or intracranial hemorrhage.

— Head CT is the modality of choice in the acute period (the first 24 hours) because of its immediate availability and higher sensitivity for intracranial bleeding and skull fracture compared with MRI.

Table 36-1. Normal Ranges for Balanced Error Scoring System Scores

Data from Ozinga SJ, Linder SM, Miller Koop M, et al. Normative performance on the balance error scoring system by youth, high school, and collegiate athletes. Journal of Athletic Training. 2018;53(7):636–645.

■Obtain a head CT if Glasgow Coma Scale score is lower than 14 or if there are signs of altered mental status (agitation, somnolence, repetitive questioning, slow response to verbal communication) or of basilar skull fracture.

■Consider CT if there is a history of LOC, severe headache, severe mechanism of injury, or history of recurrent vomiting.

— MRI is best used after the acute period to evaluate for other structural abnormalities that may be causing prolonged or worsening symptoms such as cerebral contusion, subdural hematoma, Arnold-Chiari malformation, mass lesion, or changes in brain tissue.

— Emerging neuroimaging modalities include magnetic resonance spectroscopy, diffusion-tensor imaging, functional MRI, and positron emission tomography.

■These techniques hold promise for identifying biomarkers and subtle changes missed at conventional imaging, which may improve concussion diagnosis and management in the future.

■However, all of these techniques are still being researched, and none is approved or available for clinical use.

• Neuropsychological testing

—

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