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Reviews of Current Concussion Research Literature

Journal of Neurologic Physical Therapy: July 2018 - Volume 42 - Issue 3 - p 172–173
doi: 10.1097/NPT.0000000000000232
Abstracts of Current Literature

What is the physiological time to recovery after concussion? A systematic review, by J Kamins, E Bigler, T Covassin, et al. Br J Sports Med. 2017;51:935-940.

Background and Purpose: Establishing clearance for full return to recreational activities in individuals recovering from sports-related concussion is often a difficult task for health care providers. Clinical recovery, based on the resolution of subjectively reported symptoms, is frequently used to assess an individual's readiness to return to contact sports. Recent studies, however, suggest that physiological disturbances may persist beyond the presence of clinical recovery. Furthermore, there is growing concern that individuals who return prematurely to recreational activities may be at risk for further brain damage or reinjury. The purpose of the current study was to perform a systematic review of available literature to determine a clear timeline for physiological recovery in individuals diagnosed with SRC.

Methods: A systematic review of the literature was conducted to assess the timing of physiological recovery after SRC. PubMed, CINAHL, Cochrane Central, and PsychoINFO were searched for relevant articles using the following search categories: exercise tolerance, brain physiology, advanced brain imaging, blood/serum biomarkers, and functional assessment of physiology. Articles were considered relevant if they focused on physiological recovery following SRC in relation to clinical recovery, risk of reinjury, and safe timing for return to sport. Exclusion criteria included case reports, case series with fewer than 5 participants, review articles, meta-analyses, editorials, animal research, and articles unrelated to SRC. Due to the broad range of modalities used to assess pathophysiological recovery following SRC, articles were categorized and investigated based on the modality being administered.

Results: Of the 5834 articles identified, 80 were included in the review. The following diagnostic modalities and measures of physiological recovery were evaluated: functional MRI (fMRI), diffusion tensor imaging (DTI)/diffusion MRI, magnetic resonance spectroscopy (MRS), cerebral blood flow (CBF) electrophysiology, heart rate, response to exercise, fluid biomarkers, and transcranial magnetic stimulation. There was no clear timeline for physiological recovery identified. The presence of physiological dysfunction, as determined by modalities listed earlier, was found to persist beyond clinical recovery in multiple studies.

Discussion and Conclusions: Determining a clear course for physiological recovery after SRC remains a significant challenge, and evidence for establishing a reliable timeline is lacking. Major limitations include the absence of standard parameters for physiological assessment, lack of a clear definition for concussion, and variability in methodology between studies evaluated. It does appear, however, that time required for physiological recovery may exceed that required for clinical recovery. This poses concern when using clinical assessments to determine readiness for return to sport; individuals may be at risk for further damage if physiological dysfunction exists despite symptomatic recovery. Due to a dearth of generalizable data, the authors recommend that health care providers, while continuing to rely on clinical recovery for assessment, should consider prescribing graded physical activity prior to full return to sports in order to reduce the potential risk of worsening brain dysfunction. Future research is needed to truly investigate the timeline of complete recovery after SRC and the implementation on clinical care with regard to physiological dysfunction and participation in preinjury recreational activities.

Abstracted by:

Anne K. Lennon, PT, DPT

Department of Occupational Therapy and Physical Therapy, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio

Feasibility of early physical therapy for dizziness after a sports-related concussion: a randomized clinical trial, by JC Reneker, A Hassan, RS Phillips, MC Moughiman, M Donaldson, and J Moughiman. Scand J Med Sci Sports. 2017;27(12):2009-2018.

Background and Purpose: Symptoms of dizziness are common after concussion. Many consensus-based documents have recommended active physical therapy to manage dizziness in postconcussion individuals. There are no clear guidelines, however, describing progressive physical therapy interventions for concussion-derived dizziness. The purposes of this study were to assess the feasibility and estimate the effect size of an individualized, progressive intervention compared with a generic, nonprogress intervention.

Methods: The study was a double-blinded, prospective, randomized trial. Athletes (aged 10-23 years) who were diagnosed with an acute concussion and dizziness were recruited. Participants were included, if their Post-Concussion Scale (PCS) revealed either a score of at least 3 out of 7 on the dizziness item, or a total of 10 on the migraine cluster items and at least 1 on the dizziness item, or if their examination identified vestibular, ocular, or cervical abnormalities. The experimental group received pragmatic, progressive interventions, which were prescribed based on each participant's examination findings. Activity intensity and progressions were modified to the participant's symptom responses and sports. The control group received nonprogressive, subtherapeutic interventions, aimed to be nonsymptomatic and not specific to the participants' impairments or sports. Both groups participated twice per week for 8 sessions or until cleared to return to play (RTP). The Kaplan-Meier (KM) product-limit and Cox proportional hazards (CPH) regression were used to test for differences between the groups for days to PCS recovery and days to medical clearance for RTP.

Results: The study required 14 months to randomize 41 individuals. One hundred percent of physical therapy examinations and interventions followed the study protocol timeframe and 85% of participants completed the study. KM plots revealed a mean of 13.5 and 17 days to PCS recovery, and a mean of 15.5 and 26 days to clearance to RTP for the experimental and control groups, respectively. CPH ratios (95% confidence interval) favoring the experimental group were 2.91 (1.01-8.43) for medical clearance and 1.99 (0.95-4.15) for PCS recovery. During the study period, 14% and 37% did not attain PCS recovery and 18% and 42% did not receive clearance to RTP for the experimental and control groups, respectively.

Discussion and Conclusions: The research protocol was feasible, but recruitment took longer than expected. The study interventions were safe when implemented in athletes as early as 10 days postconcussion. Study therapists required experience in both orthopedic and neurological physical therapies. The experimental group had faster PCS recovery and medical clearance to RTP, and more individuals attained these outcome. A higher dropout number in the control group may have added bias. Some participants may have benefitted from a longer duration of care. Athletes who have dizziness 10 days postconcussion may benefit with individual-specific physical therapy. This feasibility study supports the development of a larger, definitive trial.

Abstracted by:

Anne K. Galgon, MPT, PhD, NCS

Department of Physical Therapy, University of the Sciences, Philadelphia, Pennsylvania

Can vestibular rehabilitation exercises help patients with concussion? A systematic review of efficacy, prescription and progression patterns, by DA Murray, D Meldrum, and O Lennon. Br J Sports Med. 2017;51:442-451.

Background and Purpose: With 1.6 million to 3.8 million concussions being reported yearly due to sports alone, attention in the media, rehabilitation, and research have grown substantially around this topic. While the majority of individuals spontaneously recover from concussion, persisting symptoms may linger causing frustration, delayed return to work, school, and/or sport as well as increased morbidity. Common vestibular symptoms that persist postconcussion are dizziness, vertigo, and balance dysfunction and are associated with vestibular impairment, for which vestibular rehabilitation therapy (VRT) has been recommended. This systematic review by Murray et al aimed to answer the questions: (1) Does vestibular rehabilitation (VR) improve subjective reports of dizziness and vertigo, gaze stabilization deficits, balance impairment, and gait impairment? (2) Does VR facilitate early return to sports and/or work?

Methods: A systematic review was conducted using PRISMA guidelines. PubMed, CINAHL, EMBASE, SPORTDiscus, and Web of Science were searched. After screening titles and abstracts, full-text articles were reviewed. An article or abstract was selected if it met 4 criteria: (1) represented original research, (2) the subjects sustained a concussion and had vestibular symptoms, (3) VRT interventions were detailed, and (4) treatment outcomes were measured using before and after VRT. A secondary interest was the description of VRT treatment and its progression. Abstracts and full manuscripts were reviewed by 2 reviewers, and the same 2 reviewers extracted the data. Risk of bias was also assessed using different assessment tools depending on the type of evidence. Heterogeneity of study types and outcome measures did not allow data meta-analysis. Ten articles met the inclusion criteria for the systematic review.

Results: The best evidence synthesis statement reports that there is level 3 evidence to support improvements in the Dizziness Handicap Score after VRT, as well as improvements in dynamic visual acuity with gaze stabilization exercises. Level 3 evidence also supports improved balance impairment following a daily home program of VRT and balance measured by the Sensory Organization Test and the Activities-specific Balance Confidence Scale. There is improvement in gait following gait retraining as a component of VRT measured with the Dynamic Gait Index, Functional Gait Assessment, and Time up and Go. No level 1 evidence currently exists to support that VRT after mild traumatic brain injury/concussion improves dizziness, dynamic visual acuity, balance, or gait. There is level 1 randomized controlled trial (RCT) evidence to support the combination of physical therapy directed at the cervical spine and VRT after concussion for return to sports. No evidence exists to support that VRT facilitates earlier return to work. As for prescription and progression patterns, there was a lack of standardization across studies. One study was identified as providing the most detailed exercise intervention categorized using the FITT criteria (frequency, intensity, time, and type) using eye-head coordination exercises, static balance, and ambulation exercises as their top 3 choices. As symptoms improved, exercises were progressed by increasing difficulty.

Discussion and Conclusions: It is clear that more high-quality RCTs of VRT after concussion is required to determine when to begin vestibular rehabilitation, appropriate prescription, and dosage of the intervention and also to determine its effectiveness. This review suggests with a low level of evidence that VRT is beneficial in concussion with evidence supporting earlier return to sports.

Abstracted by:

Airelle Giordano, PT, DPT

Department of Physical Therapy, University of Delaware, Newark, Delaware

© 2018 Academy of Neurologic Physical Therapy, APTA