Pediatric Concussion: Current Trends and New Frontiers

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BRIEF COMMUNICATION

Dr Torres is Director of the Pediatric Traumatic Brain Injury Program at Boston Medical Center and Assistant Professor of Pediatrics and Neurology at Boston University School of Medicine. He is also a member of the Department of Public Health, Sports Concussion Expert, Clinical Advisory Committee. Dr Shaikh is from SMIMER Medical College and Research Assistant at the Pediatric Trauma Brain Injury Program, Boston Medical Center.

The term concussion came to fame in the past decade, as is evidenced by the increase in the number of concussion-related publications in recent years. With fame came a lot of confusion and controversy related to its definition, diagnostic criteria, management and return to a normal lifestyle. In addition, there is a significant knowledge gap in concussion care and management amongst health care providers.¹ Although there is no universally accepted definition for a concussion, the American Academy of Neurology describes a concussion as a trauma-induced alteration in mental status that may or may not involve loss of consciousness.² Explained differently, a concussion is an abnormality in the biochemical processes leading to functional impairment without any evidence of structural findings on standard neuroimaging.

To add to the confusion, concussion has been interchangeably used with the term mild traumatic brain injury; this equivalence is up for debate as some believe that the traumatic brain injury may have a more severe course.  In this article, we provide a brief discussion on the impact of concussion on the pediatric population, the current trends in concussion care, recent advances, future implications, and the challenges faced in the management of concussion.

Concussion in pediatrics

A concussion is a complex condition that has been poorly studied in the pediatric population. The effect and outcome of concussion are far worse in the developing brains of children as compared to that of adults. Studies have shown that concussion in this age group significantly impacts school and sports-related performance, and it often leads to significant academic, social, and financial losses. Concussion may even cause permanent damage and worsening of existing neuropsychological symptoms. Most concerning, repeated head injuries, particularly recurrent and prolonged subconcussive injuries, may lead to a much more severe condition like the chronic traumatic encephalopathy. 

Issues in diagnosis

The diagnosis of concussion is mostly clinical and is based on the presence of a constellation of symptoms developed as a consequence of trauma to the head (directly or indirectly). It is suspected with the presence of any of the following symptoms: headache, loss of consciousness, confusion, dizziness, and nausea and vomiting.¹ There are many assessment tools that aid in the diagnosis of concussion, including:

• The Post-Concussion Symptom Scale (PCSS)
• Sport Concussion Assessment Tool 5 (SCAT 5)
• Standard Assessment of Concussion (SAC)
• Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT)
• Concussion Resolution Index (CRI) 
• King-Devick (KD) test

However, the subjective nature of these assessment tools limits their utility.³ Currently, there is no imaging or laboratory test to diagnosis concussion. Traditional neuroimaging like CT scan and MRI that are used to rule out more serious traumatic brain injury are of little value in diagnosing concussion, as they only identify structural abnormalities. Also, the possibilities of radiation with CT scan and need for sedation in MRI restricts the use of these modalities to certain conditions. While a protocol has been established for the use of the CT scan in traumatic brain injury (ie, the PECARN rule), there is no protocol for the use of MRI. As such, clinician discretion determines MRI use in the pediatric population.

Since concussion is a functional disorder, attempts have been made to identify vascular and metabolic abnormalities through newer imaging modalities, laboratory tests (eg, fluid biomarkers), genetic testing, and electrophysiology. Recent advances in neuroimaging modalities like diffusion tensor imaging (DTI), magnetic resonance spectroscopy (MRS), functional MRI (fMRI), susceptibility-weighted imaging (SWI), and the like have shown potential use in the diagnosis of concussion.

DTI is a noninvasive method that allows estimation of the integrity of white matter tracts and has validated use in detecting axonal damage.⁴ Functional MRI shows abnormality in the blood oxygenation through BOLD (blood oxygenation dependent) signals in a concussed brain.⁵ Changes in N-acetylaspartate (NAA)/creatine and NAA/choline ratios can be detected on MRS, but the utility of these techniques only have been studied in a research environment and their routine clinical use has not been established yet.  Transcranial-Doppler ultrasound (TCD) is an exciting modality that measures the cerebrovascular reactivity index, mean velocity of blood flow, and pulsatility index. It has already been shown that the cerebrovascular reactivity decreases post-concussion and that concussion can be effectively diagnosed through TCD. TCD provides a noninvasive and low-cost option, but further research is required before routine use.⁶

Another area of exploration is the biomarkers measured by the blood or CSF and their potential use in the diagnosis of concussion. The most extensively studied blood-based biomarker is S100β. Glial fibrillary acidic protein, Tau, neurofilament light protein, neuron-specific enolase, and amyloid protein are some of the commonly used blood biomarkers.⁷ The role of cerebrospinal fluid (eg, serum albumin ratio, 1176 residue N-terminal fragment of α-spectrin, brain-derived neurotrophic factor [BDNF], ubiquitin C-terminal hydrolase L1, creatinine kinase and heart-type fatty acid binding protein) also have been studied for their possible use in concussion diagnosis.

These biomarkers are of interest since they may play a potential role in the progression and recovery of a concussion. It is hypothesized that biomarkers, in combination with neuroimaging and clinical assessment, will aid in the diagnosis of concussion.^7,8 Numerous genetic biomarkers with polymorphisms concerning apolipoprotein E, glutamate ionotropic receptor N-methyl-D-aspartate -type subunit 2A, BDNF, and the like are being studied for their potential use in a concussion. The sensitivity of these biomarkers increase significantly when used in combination.⁹ While all of these biomarkers are currently limited to research environments, they may be useful for clinical concussion assessment in the near future.

Management and care

Often concussion care becomes challenging for pediatric specialists, as the approach needs to be individualized for each patient. The management of concussion is crucial, since delayed management or early clearance may lead to potential complications such as second impact syndrome. Since there is limited awareness amongst teachers, trainers, athletes, and patients about the impact of a concussion, management can be challenging.

It is universally accepted that concussion responds to adequate physical, cognitive. and psychological rest and, in the absence of better evidence, needs to be individualized for every patient. The athlete should be removed from active sports to avoid another concussion or any form of additional injury that may exacerbate the present concussion symptoms and prolong recovery time. Proper rest also requires that the child does not attend school and avoids any mentally exhausting activities such as homework, video games, and excessive screen time. This, however, becomes challenging under numerous external pressures, especially with the failure of academic and sports personnel and family members in recognizing the effects of concussion. Similarly, patients may not be able to acknowledge concussion severity in the absence of any apparent sign and symptoms.  Hence, concussion education for sports and academic professionals should emphasize the need for reasonable rest until the resolution of symptoms and the removal of stressful activity that worsens the condition.

For patients who do not respond to rest only, symptomatic pharmacological treatment may be used. Analgesics or nonsteroidal anti-inflammatory drugs may be used for headaches, but excessive use should be avoided to prevent rebound headaches. Concussion patients often complain of sleep disturbances in the form of delayed onset sleep or excessive daytime sleepiness. Sleep hygiene usually helps patients. Due to its safety profile, melatonin has been used to assist patients with sleep, but its efficacy has not been established for concussion patients. For patients experiencing nausea or vomiting, ondansetron is an optimal treatment; metoclopramide and promethazine should be avoided in children because of their adverse effects.

Some patients have prolonged symptoms that may progress to post-concussive syndrome. In such cases, a multidisciplinary approach involving pediatric neurologists, neuropsychologists, physical therapists, psychiatrists and other specialists becomes essential. 

Looking forward

Future research is needed to address the common clinical challenges.  For instance, long questionnaires are used as the gold standard in concussion clinics around the globe, but they are not always practical in the acute setting. This is especially true if patients are very symptomatic and in cases where comorbidities are present. Similarly, the severity score is important, but the long list of symptoms requires physicians to take the history of many symptoms that may not impact care management. Not only does this extend the evaluation time, but it also can make patients feel uncomfortable. A biological marker could help in the diagnosis, but numerous efforts currently underway have not been yet validated. 

The current treatment philosophy also presents a dilemma.  While it is agreed that patients benefit from rest, protocols often require patients to see multiple specialists. Instead of decreasing stress, this may be adding to it by interfering with the process of returning to school and normalcy. Finally, it is important to collaborate with primary care colleagues to ensure complex cases receive timely referrals to neurologists to avoid mismanagement and expedite coordinated efforts of recovery.

References:

1. Mann A, Tator CH, Carson JD. Concussion diagnosis and management: Knowledge and attitudes of family medicine residents. Can Fam Physician. 2017;63:460-466.

2. Kirkwood MW, Yeates KO, Wilson PE. Pediatric sport-related concussion: A review of the clinical management of an oft-neglected population. Pediatrics. 2006;117:1359-1371.

3. Dessy AM, Yuk FJ, Maniya AY, et al. Review of Assessment Scales for Diagnosing and Monitoring Sports-related Concussion. Cureus. 2017; 9(12):e1922.

4. Bartnik-Olson BL, Holshouser B, Wang H, et al. Impaired neurovascular unit function contributes to persistent symptoms after concussion: a pilot study. J Neurotrauma. (2014)31:1497–506.

5. Di Battista, Churchill N, Schweizer TA et al. Blood biomarkers are associated with brain function and blood flow following sport concussion. J  Neuroimmunol. 319:1–8.

6. Thibeault CM, Thorpe S, O’Brien MJ et al. A cross-sectional study on cerebral hemodynamics after mild traumatic brain injury in a pediatric population. Front Neurol. 2018; 9:200.

7. Papa L. Potential blood-based biomarkers for concussion. Sports Med Arthrosc Rev. 2016; 24(3):108-115.

8. Zetterberg H, Smith DH, Blennow K. Biomarkers of mild traumatic brain injury in cerebrospinal fluid and blood. Nat Rev Neurol. 2013; 9(4):201-210.

9. Jeter CB1, Hergenroeder GW, Hylin MJ, et al. Biomarkers for the diagnosis and prognosis of mild traumatic brain injury/concussion. J Neurotrauma. 2013; 30(8):657-70.