Moser et al.

BioMedical Engineering OnLine (2025) 24:48 BioMedical Engineering

https://doi.org/10.1186/s12938-025-01380-x
OnLine

RESEARCH Open Access

Complexity of post‑concussion syndrome

assessment and management: a case
for customizing rehabilitation
Nicholas Moser1,2*, Milos R. Popovic1,2,3,4,5 and Sukhvinder Kalsi‑Ryan1,4

*Correspondence:
Nicholas.moser@uhn.ca Abstract
1
KITE Research Institute- Background: Post-concussion syndrome is a challenging condition to manage
University Health Network, for even the most experienced chronic pain experts. Patients’ presentations are het‑
Toronto, ON, Canada erogeneous with symptoms spanning physical, cognitive and emotional domains. The
2
Temerty Faculty of Medicine,
Institute of Medical Science, symptoms reported are often non-specific, making it difficult for health profession‑
University of Toronto, Toronto, als to prescribe effective rehabilitation. The aim of the present study was to examine
ON, Canada the effectiveness of a customized rehabilitation program based on subgroup determi‑
3
Institute of Biomedical
Engineering, University nation following a standardized clinical exam in adults with post-concussion syndrome.
of Toronto, Toronto, ON, Canada Methods: A total of 16 adults (mean age ± SD, 38.3 ± 12.5 years) with post-concussion
4
Rehabilitation Sciences
Institute, University of Toronto, syndrome participated in a 6-week rehabilitation program. Participants were recruited
Toronto, ON, Canada from external community concussion clinics around the greater Toronto area, Canada.
5
Mechanical and Industrial Participants underwent a comprehensive standardized clinical exam to subgroup
Engineering, University
of Toronto, Toronto, ON, Canada the ostensible symptom generators into either autonomic, cervical or vestibulo-ocular.
Customized rehabilitation was then prescribed based on their subgroupings. The
primary outcome measure was the Rivermead Post-Concussion Questionnaire (RPQ).
Secondary outcome measures included the Patient Health Questionnaire-9 (PHQ-9),
the Neck Disability Index (NDI), and exercise tolerance as assessed via the Buffalo Con‑
cussion Treadmill Test (BCTT).
Results: Following 6 weeks of customized rehabilitation, participants on average
experienced a significant and clinically meaningful change with respect to the RPQ-3
and RPQ-13 (p < 0.001). We also observed a significant change in all secondary out‑
come measures including a reduction in PHQ-9 (p < 0.01), NDI (p < 0.001) and exercise
tolerance, expressed as heart rate threshold (p < 0.001).
Conclusion: The standardized exam was feasible and useful in assisting the clinician
in prescribing effective rehabilitation. The 6-week customized rehabilitation program
demonstrated significant changes in patient-reported persistent post-concussion
symptoms and exercise tolerance. The implementation of a customized program based

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Moser et al. BioMedical Engineering OnLine (2025) 24:48 Page 2 of 15

on a standardized exam performed to subgroup the ostensible symptom generators may

be key to successful management in this population.

Background
Post-concussion syndrome (PCS) is a highly contested diagnosis [1] with much debate
among clinicians and epidemiologists. Symptoms have been shown to be non-specific
and the myriad of those reported can include physical complaints, such as headaches
and dizziness; cognitive complaints, such as brain fog and impaired working memory;
and affect/mood related issues, such as anxiety and depression as well as sleep impair-
ment [2]. A main tenet to the debate is that there is currently no universally agreed upon
definition for PCS with highly varied criteria between the current definitions used [3].
The heterogeneity of definitions used and criteria applied for clinical trials precludes the
ability to perform meta-analyses and compare findings between trials. Ultimately this
constrains our ability to generalize the findings and our ability to better understand the
effects of rehabilitation on a larger scale.
Doubt surrounding PCS being a unique clinical entity largely stems from the current
lack of organic injury unique to this condition or as the reliable cause for the reported
symptoms. Preliminary evidence does indicate abnormal cerebral metabolism and per-
fusion [4] as well as electrophysiological recordings [5] in those with persistent symp-
toms. However, the few large-scale prognostic studies utilizing imaging modalities to
identify these aforementioned impairments have limited utility given their small effects
on outcomes [6]. There is also a lack of evidence comparing this population to an injured
non-traumatic brain injury (TBI) control group [4, 7]. This is a necessary next step, given
these populations have high rates of overlapping reported symptoms [1, 3]. Without an
agreed upon reliable cause for the reported persistent symptoms a coherent evidence-
based rehabilitative strategy remains enigmatic.
The implementation of reliable and objective diagnostic testing outside the acute set-
ting has been largely absent. Currently there is a lack of valid and reliable outcome meas-
ures to assess persistent symptoms and their resolution following intervention. However,
the Buffalo Concussion Treadmill Test (BCTT) and the widely utilized Rivermead Post-
Concussion Questionnaire (RPQ) have been validated [8–10] and are two reliable tests
that have utility in concussion studies [11, 12]. Regrettably, there is still no agreed upon
RPQ score that would qualify as clinically relevant. Miller et al. [13] established a 15%
cutoff for clinically meaningful changes in their clinical trial [13]. This cut-off score has
been adopted by others [14] but it remains to be validated [15]. This is an important next
step given observations made by Vikane et al., (2017) reporting that the RPQ appears to
measure different features as the sum of scores differed in clinical significance from the
total number of reported symptoms [14].
Despite contention regarding the diagnostic criteria and current lack of available bio-
markers to confirm or refute the disorder, a significant minority of patients continue to
report the persistence of symptoms following a concussive injury [16]. The most recent
review found that one in three patients who present to the emergency department for
a concussive injury will continue to report symptoms at the 6-month mark [17]. If it
is not properly addressed this disorder can become problematic. Graff et al. [18] noted
Moser et al. BioMedical Engineering OnLine (2025) 24:48 Page 3 of 15

that 43% of patients who suffer a mild traumatic brain injury (mTBI) do not return to
ordinary work 5 years post-injury [18]. In Ontario alone, the conservative estimated cost
to medically manage this population was reported to be over $110 million annually [19].
Thus, there is a need to further evaluate more effective rehabilitation options.
Consistently higher quality of evidence is emerging for exercise and multimodal ther-
apy; however, there is a need to further evaluate different therapies and refine exercise
prescriptions (dose, frequency and intensity) given the varied responses and number of
patients with persistent complaints despite therapy [20, 21]. Leddy et al. [22] proposed
a systematic clinical examination to help the clinician identify one or more clinical pro-
files of the post-concussion patient in order to prescribe targeted therapies to optimize
recovery [22]. This structured approach to concussion assessment and management is
based on the notion that patients’symptoms emanate not only from the globally con-
cussed brain, but also reflects dysfunction in sub-systems such as the cervical spine. By
identifying the concussion subtypes, the rehabilitative approach can be customized to
the patient and theoretically facilitate improved recovery.
The objective of this study was to define the effectiveness of a customized treatment
program based on the findings of a standardized clinical exam performed to subgroup
the ostensible persistent post-concussion symptom generators. More specifically, we
report on the outcomes of a 6-week customized rehabilitation program in adults who
suffer persistent post-concussion symptoms and have remained symptomatic despite
having already undertaken rehabilitative care. This paper defines the results and also
touches on the feasibility and clinical utility of the standardized exam to subgroup per-
sistent post-concussion symptoms in adult patients for rehabilitation guidance.

Results
Participant demographics
A total of 16 adults participated in the study. All 16 participants that were enrolled com-
pleted the 6-week rehabilitation program. The rehabilitation participants received was
customized based on the standardized exam performed at baseline. The intention of the
standardized exam was to subgroup participants’ non-specific symptoms into ostensible
symptom generators that the rehabilitation targeted.
No adverse events were reported by participants. As depicted in Table 1, the average
age of the study population was 38 years with the majority of the participants (13 of 16)
being female. There was a wide range of reported number of prior concussions (0–11) as
well as symptom duration (1–8 months) prior to undertaking the rehabilitation program
as part of this study. Only one participant reported undertaking additional treatment
while in the trial, which encompassed occupational and vision therapy. They disclosed
that they began these therapies before admittance to the trial. On average, participants
demonstrated adherence with the rehabilitation recommendations, exceeding 80% (81.4
+ 11) self-reported adherence to the recommended at-home exercises.
At baseline, defined as the point of enrollment, participants demonstrated a high
symptom burden through their RPQ-3/13 questionnaire scores and the total num-
ber of RPQ symptoms reported. On average participants reported having moderate
Moser et al. BioMedical Engineering OnLine (2025) 24:48 Page 4 of 15

Table 1 Demographics and clinical characteristics (N = 16)

Years of age (mean ± SD, range) 38.3 ± 12.5, 21–61

Sex (male/female) 3/13
Race (White/Hispanic/Arab/Indian/Asian) 9/1/2/2/2
Number of prior concussions (mean ± SD, range) 2.1 ± 3, 0–11
Duration of symptoms, months (mean ± SD, range) 4.3 ± 1.9, 1–8
Mechanism of injury (MVA/sport/workplace/fall/other) 3/6/2/4/1
Baseline RPQ-3 score {out of 12} (mean ± SD, [95% CI]) 7.1 ± 2.1, [6.1–8.2]
Baseline RPQ-13 score {out of 52} (mean ± SD, [95% CI]) 27.4 ± 9.3, [22.8–31.9]
Baseline RPQ total symptom count {out of 16} (mean ± SD, [95% CI]) 11.8 ± 3.6, [10.2–13.4]
Baseline PHQ-9 score {out of 27} (mean ± SD, [95% CI]) 13.1 ± 5.5, [10.3–15.7]
Baseline NDI score {out of 50} (mean ± SD, [95% CI]) 19.1 ± 5.8, [16.2–21.9]
Baseline BCTT result (percentage failed; mean heart rate BPM ± SD [95% CI]; heart rate 81%; 148.2 ± 23.8
range) [137.8–158.6];
118–187
SD, standard deviation; CI, confidence interval; RPQ, Rivermead Post-Concussion Questionnaire; PHQ-9, Patient Health
Questionnaire; NDI, Neck Disability Index; BPM, beats per minute; BCTT, Buffalo Concussion Treadmill Test

Table 2 Post-concussion symptom subgroup based on standardized clinical exam (N = 16)

Subgroup determination Autonomic, cervical and vestibulo-ocular Autonomic and cervical Cervical

Number of participants 3 10 3

perceived depressive symptoms and moderate perceived neck disability as measured

by the PHQ-9 and NDI, respectively (Table 1). As per the findings of the standard-
ized exam, no participant demonstrated any hard neurological signs. All participants
demonstrated an objective cervical spine impairment placing them into the cervi-
cal disorder subgroup. Thirteen of the participants had autonomic impairment as
demonstrated by exercise intolerance and three of the 16 participants had an abnor-
mal vestibular or oculomotor screen. Therefore, the majority of participants (13/16)
demonstrated multiple subgroup impairments requiring multimodal therapies to
address the various identified impairments (Table 2).

Effects of customized rehabilitation on reported symptoms

Following 6 weeks of customized rehabilitation, participants made clinically mean-
ingful changes in both the primary and secondary outcome measures (Table 3). On
average participants’ RPQ-3 scores reduced from 7.1 (out of 12) at baseline to 2.5
exceeding the two-point change needed for MCID. On average, participants also
lowered their RPQ-13 scores from 27.4 (out of 52) at baseline to 14.1 exceeding the
MCID of eight points. The participants total symptom count reduced on average by
4.5 exceeding a significant change (p < 0.001).
With respect to the secondary outcomes, participants improved their baseline per-
ceived self-rated depression scores as measured by the PHQ-9 from 13.1 (moderate
depression) at baseline to an 8.6 (mild depression) at follow-up (p < 0.01). Partici-
pants improved their baseline perceived self-rated neck disability scores, as meas-
ured by the NDI, from 19.1 (moderate disability) at baseline to 11.4 (mild disability)
Moser et al. BioMedical Engineering OnLine (2025) 24:48 Page 5 of 15

Table 3 Overview of primary and secondary outcomes following 6-week rehabilitation

Primary and secondary Mean 6-week follow-up Mean change in outcome P-value
outcome measures outcome measure scores measure scores from baseline
to 6-week follow-up

RPQ-3 score [out of 12] (mean 2.5 ± 2, [1.7–3.5] 4.6 ± 2.4, [3.5–5.6] p < 0.001
± SD, [95% CI])
RPQ-13 score [out of 52] (mean 14.1 ± 9.8, [9.8–18.4] 13.3 ± 8.4, [9.5–16.9] p < 0.001
± SD, [95% CI])
RPQ total symptom count [out 7.3 ± 4.3, [5.4–9.2] 4.5 ± 4, [2.7–6.3] p < 0.001
of 52] (mean ± SD, [95% CI])
PHQ-9 score [out of 27] (mean 8.6 ± 4.5, [6.7–10.6] 4.4 ± 6, [1.7–7] p < 0.01
± SD, [95% CI])
NDI score [out of 50] (mean 11.4 ± 7.3, [8.2–14.6] 7.8 ± 6.8, [4.7–10.7] p < 0.001
± SD, [95% CI])
BCTT result (percentage failed; 18%; 176 ± 17.4, [168.4–183.6]; 27.8 ± 24.1, [10.6–38.4] p < 0.001
heart rate mean BPM ± SD [95% 145–195
CI]; heart rate range BPM)
SD, standard deviation; CI, confidence interval; RPQ, Rivermead Post-Concussion Questionnaire; PHQ-9, Patient Health
Questionnaire; NDI, Neck Disability Index; BPM, beats per minute; BCTT, Buffalo Concussion Treadmill Test

at follow-up. Although a statistically significant change (p < 0.001) was achieved, the
findings do not reflect a clinically meaningful change through the suggested MCID
[44].

Effects of customized rehabilitation on exercise tolerance

There was a considerable change in the number of participants with exercise intoler-
ance following the 6-week customized rehabilitation. As depicted in Table 3, the num-
ber of participants who had exercise intolerance as measured by the BCTT decreased
from 13 participants at baseline to three by the end of the program. This coincided
with a statistically significant (p < 0.001) increase in participants’ mean heart rate
threshold, increasing from 148 BPM at baseline to 176 BPM at follow-up.

Discussion
A 6-week customized rehabilitation program led to significant changes in self-
reported symptoms and exercise tolerance in adults with persistent post-concussion
symptoms who had previously limited response to therapy.
At the end of the trial only 18% of participants (n = 3 of 16) continued to demonstrate
exercise intolerance. This was a significant (p > 0.001) change from baseline where over
80% of participants showed exercise intolerance. Participants significantly reduced
their self-reported symptoms, dropping on average by 4.6 points on the RPQ-3 and by
13.3 points on the RPQ-13. This exceeded the established MCID of two points on the
RPQ-3 and eight points on the RPQ-13. Furthermore, participants following the cus-
tomized rehabilitation program reduced on average the total number of symptoms by
4.5. To the authors’ knowledge, there is currently no agreed upon change in the number
of symptoms following intervention that would be deemed clinically meaningful. Tator
et al. showed that each additional concussion symptom a patient experiences reduces
the recovery rate by 25%. As such, future examination of effective rehabilitation should
Moser et al. BioMedical Engineering OnLine (2025) 24:48 Page 6 of 15

not solely focus on the impact of reducing symptom severity, but also on how rehabilita-
tion can reduce the total number of symptoms reported [23].
Prior to the 6-week customized rehabilitation program, all 16 participants reported
undertaking extensive rehabilitation that included physical therapies to the neck,
balance exercises and advice to exercise aerobically. Despite this therapy, their self-
reported symptoms had persisted on average for 4.5 months and were still rated as
severe. Although participants had been directed to exercise, all but three had contin-
ued objective exercise intolerance.
Participants’ clinical presentations were heterogeneous. Specifically, at baseline partic-
ipants endorsed on average 12 of 16 symptoms on the RPQ and following the standard
examination various subgroup profiles were identified (Table 2). Complaints of persis-
tent neck pain, sleep impairment and cognitive issues are common impairments in this
population. Two commonly endorsed persistent symptoms, headaches and dizziness,
have varied presentations, etiology and responses to therapies that drive uncertainty
in the decisions attending health care practitioners make for their patients’ rehabilita-
tion. As shown by the significant self-reported symptom changes post-rehabilitation,
the standardized exam afforded the clinician to make a more informed decision regard-
ing rehabilitative prescription despite the apparent complexity of this population’s
presentation.
The average time taken to complete the standardized examination and the primary and
secondary outcome measures was 60 min. Almost all components of the exam can be
done at any physical therapy office; however, a few pieces of equipment such as a tread-
mill, heart rate monitor and a laser pointer for neck proprioception testing are required
and may not be present at all clinics. Although the majority of the tests in the exam con-
tinue to be reliant on patients’ self-reported symptom exacerbation, the standardization
of the clinical exam afforded a step-by-step approach to delineate non-specific symptom
generators into ostensible subgroup(s) that were the presumed driver(s) for persistent
impairments. Theoretically, this afforded the clinician with a more precise rehabilitation
plan leading to improved patient-reported outcomes.
A consistent piece of feedback from the participants following the re-examination at
6 weeks was that the education regarding the subgroups and drivers of their persistent
symptoms explained by the exam provided the needed reassurance for their prescribed
rehabilitation. It is the opinion of the authors that the standardized exam is not only
feasible regarding time for implementation but highly useful in directing patient care.
Participant compliance is known to be low with rehabilitative recommendations, which
likely has an impact on recovery. Given the high self-reported adherence to rehabilitative
recommendations, the aforementioned education likely facilitated behavioral changes.
A major question that remains is why the participants responded well to a reha-
bilitation program despite previously undertaking therapies recommended by the
current clinical guidelines [24] with no meaningful changes. As previously noted, at
baseline 13 of the 16 participants continued to demonstrate exercise intolerance. By
the end of the 6-week program that number dropped to three. As such, the answer to
the question may reside in the differences in exercise form and intensity prescribed
in the given rehabilitation program. In the customized program, participants’ exer-
cise tolerance was re-examined weekly and their prescribed exercise training intensity
Moser et al. BioMedical Engineering OnLine (2025) 24:48 Page 7 of 15

of 85–90% below symptom threshold continued to be progressed along with their

recovery. It is well documented that there is considerable variance in the response to
a general exercise program [44–46] as measured by changes in muscle strength, size
and cardiorespiratory fitness. The HERITAGE Family Study illustrated that regard-
less of age, sex, race and prior fitness status there are low, medium and high exer-
cise “responders” [47]. The abolishment of exercise “non-responders” occurs when
the exercise training dosage (time, frequency, volume and intensity) are manipulated,
particularly the intensity [46, 49]. The progressive moderate-to-vigorous steady-state
aerobic training participants undertook as part of this rehabilitation program may
have been sufficiently intense to stimulate cardiovascular adaptations unlike the prior
exercise training. Additional reasons for the observed changes in exercise tolerance
exist and can include increased adherence compared to previous therapy programs
they attempted given that participants were seen twice per week and self-reported
greater than 80% engagement with the at-home rehabilitation recommendations.
This study has several strengths. Firstly, the demographics in this study make it
among only a few rehabilitation trials that have examined a population outside young
healthy high school or collegiate athletes [21]. Albeit the demographics were highly
skewed to females, this is likely due to their documented increased risk of report-
ing persistent symptoms [23]. Secondly, all participants had undertaken prior therapy
before being enrolled in the rehabilitation program. As such, the likelihood of regres-
sion to the mean and/or the placebo effect accounting for the changes observed is
unlikely. Lastly, validated and reliable outcome measures were used to measure pre–
post change scores.
This study also has several limitations. Firstly, although we observed significant and
clinically meaningful changes in the primary and most secondary outcome measures
assessed, we were limited to a 6-week follow-up period. No longer term follow-up
was initiated. Secondly, the present study did not include an active control group to
compare the customized rehabilitation program to. Thirdly, the present study had a
limited sample size and the population incorporated was predominantly female and
of White background limiting the generalizability of the findings. Lastly, given the
limited sample size, a comparison across the differing modes/subgroups of treatments
was not made, which may have affected their response as some participants received
a “higher dose” of rehabilitation given they were placed into more than one subgroup.
As previously noted, there is a high cost associated with managing persistent post-
concussion symptoms. A part of this cost is the large number of health service visits,
which likely reflects the difficulty that patients experience in trying to find support
for their symptoms. Given the documented prevalence of this disorder and cost for
management, it is imperative that we continue to study and refine our rehabilitation
prescription. These efforts could lead to a reduction in duration and frequency of vis-
its to medical specialists and excessively long treatment plans with allied healthcare
professionals.
The present study supports the use for a standardized exam, inclusive of exercise
tolerance testing, as recommended by Matuszak et al. [25]. In a short period of time,
the customized rehabilitation program demonstrated significant changes to patient-
reported persistent post-concussion symptoms and exercise tolerance. The results
Moser et al. BioMedical Engineering OnLine (2025) 24:48 Page 8 of 15

provide preliminary evidence for superior patient-reported outcomes with a custom-

ized rehabilitation model that is based on subgrouping non-specific symptoms into
ostensible symptom generators rather than the current symptom-based treatment
approach.

Methods
Ethics approval
Ethics approval was granted by the University Health Network Research Ethics
Board (#22–5560). All participants were required to provide both verbal and written
informed consent before commencing any experimental procedures.

Study design
We conducted a 6-week prospective cohort trial. Following the standardized exam-
ination and the completion of the primary and secondary outcome measures, par-
ticipants were placed into one of three possible subgroups (autonomic, cervical or
vestibulo-ocular) [22]. Participants’ customized care was dependent on the subgroup
they were classified into. After 6 weeks of rehabilitation, participants underwent the
end-point examinations.

Population
A consecutive enrollment of 16 participants was obtained at the Toronto Rehabili-
tation Institute. 32 participants with post-concussion syndrome were screened in
2022–2023 for eligibility. Participants were recruited from external community con-
cussion clinics around the greater Toronto area (eight clinics) as well as by internal
advertisement at the University Health Network. Participants underwent therapy at
the KITE Innovations and Rehabilitation Clinics located within the Toronto Rehabili-
tation Institute, Toronto, Ontario, Canada.

Inclusion criteria
To be eligible, participants had to be 21 years and older; meet the definition of
post-concussion syndrome as defined by Tator et al. [23], which requires a patient
to report any three symptoms or more (from an inclusive list of the 40 most com-
monly reported persisting symptoms) lasting at least one month following the diag-
nosis of a concussion [23]. This definition was selected given the known limitations
of the ICD-10, the fact that DSM-IV is no longer in practice and these previous defi-
nitions are biased towards those who are vulnerable to concussions or more severe
forms of post-concussion syndrome [23]. Concussion was defined according to the
6th International Consensus Statement on Concussion in Sport [24]; have adequate
language skills in English to read and take part in rehabilitation treatment programs;
and demonstrate an objective impairment on the baseline standardized exam, placing
the patient into one of the three subgroups.

Exclusion criteria
Potential study participants were excluded should their clinical examination have
been unremarkable for any positive physical findings and therefore their dominant
Moser et al. BioMedical Engineering OnLine (2025) 24:48 Page 9 of 15

symptomatology placed them into the affective/cognition subgroup described by

Leddy et al. [22]. This exclusion was applied because we were interested in under-
standing the effects of a tailored physical rehabilitation program. As such, should
the participants have not demonstrated any physical impairment, no physical
rehabilitative interventions could be recommended. Additional exclusion criteria
included chronic infectious disease; uncontrolled hypertension; other neurological
disorders (not attributed to their primary diagnosis); cancer treatment (other than
basal cell carcinoma), craniotomy, refractory subdural hematoma; long‐term use of
psychoactive medications that would compromise their ability to comprehend and
perform study activities; those with pacemakers or elevated cardiovascular risk;
ongoing litigation surrounding their injury; those diagnosed with a moderate or
severe brain injury prior to enrollment, or their persistent post-concussive symp-
toms had persisted beyond 12 months. Over the course of recovery there is a shift
in the domain of symptom reporting with a reduction in physical symptoms and a
stable or increase in cognitive and emotional/mood related symptoms [16]. As such,
we applied this time restriction.
16 of the 32 participants screened were ineligible due to the duration of their
symptoms exceeding one year (n = 11), had no positive examination findings to jus-
tify placement into one of the three subgroups (n = 3), or they could not comply with
frequency of care (n = 2).

Assessments/procedures
Participants underwent a comprehensive standardized clinical examination at
the KITE Innovations and Rehabilitation Clinics to differentiate their post-con-
cussive subgroup(s) [22]. Evaluation consisted of the recommended elements of a
standardized clinical physical examination outlined by Matuszak et al. (2016) [25].
Specifically, the study coordinator (NM), a licensed chiropractor, performed all
components of the examination including a neurological exam consisting of cranial
nerve screen, motor testing of the upper and lower extremities and deep tendon
reflexes; a musculoskeletal examination assessing for tenderness over the head and
neck, range of motion of the cervical spine and Spurling test; joint position sense
error test (JPSE) of the cervical spine in flexion, extension, lateral flexion and rota-
tion, which has shown to be a reliable and relevant measure for the evaluation of
neck pain [26–28]; balance/coordination examination assessing static and dynamic
balance via the Balance Error Scoring System (BESS) and tandem walking with eyes
open and closed [29]. The BESS consists of three static stances performed on both
a firm and foam surface. The BESS has been shown to have moderate-to-good reli-
ability in assessing static balance as well as has been shown to detect balance deficits
in participants with concussion [30]. Continuing, a vestibular-ocular examination
consisting of evaluation of the eyes in eight positions, evaluating nystagmus, sac-
cades, smooth pursuit and near point convergence/accommodation. More tests were
included if dizziness or imbalance were present: orthostatic vital signs via supine-to-
stand stress test; Dix–Hallpike maneuver and assessment of dynamic visual acuity
[31].
Moser et al. BioMedical Engineering OnLine (2025) 24:48 Page 10 of 15

In addition to the examination outlined by Matuszak et al. [25], a physical exertion

test was performed via the Buffalo Concussion Treadmill Test (BCTT) protocol to
specifically examine exercise intolerance [9].

Subgroup determination
As per the recommended elements of a standardized clinical physical examination out-
lined by Matuszak et al. in [25], a positive examination for the subgroups is outlined
below.
A positive autonomic disorder screen, placing the patient into the autonomic sub-
group, was defined as an inability to exercise at an age-appropriate heart rate thresh-
old due to the exacerbation of concussion symptoms [9]. Exacerbation of symptoms was
defined as an increase of three points or more of their reported symptoms from baseline
during exercise on an 11-point numerical rating scale (0–10). When participants could
exert themselves and achieve near their age-appropriate maximum heart rate without
exacerbation of symptoms, then the etiology or justification for persisting concussion
symptoms was ascribed to alternative problems [22].
A positive cervical spine screen, placing the patient into the cervical subgroup, was
defined as having an abnormal cervical spine range of motion with pain as assessed by
visual inspection by NM along with palpatory findings of facet joint restrictions and pain
with supine joint motion palpation, cervical myofascial trigger points, or abnormal joint
position error testing [26–28].
Finally, a positive vestibular or oculomotor screen, placing the patient into the vestib-
ulo-ocular subgroup, was defined as an abnormal vestibulo-oculomotor screen (VOMS)
[32], abnormal static and dynamic balance testing as assessed via the Balance Error
Scoring System [30] and tandem walking [29], respectively, or when clinically indicated
to perform, an abnormal vestibular special testing, such as Dix–Hallpike maneuver [31].

Intervention
The study coordinator (NM), a licensed chiropractor with extensive experience in assess-
ing and managing chronic pain patients, performed all components of the listed assess-
ments/procedures and therapy at the KITE Innovations and Rehabilitation Clinics.

Customized care program

During the first therapy session, participants were provided reassurance and psychoedu-
cation via the bio-psycho-social model on understanding persistent symptoms [20, 21].
Participants were afforded two treatments per week over the course of 6 weeks. Thus,
participants were provided 12 treatments over the course of the 6 weeks. The time frame
of 6 weeks was selected given the treatment structure of prior clinical trials examining
the effectiveness of physical interventions to address physical symptoms such as head-
aches, dizziness and neck pain [33]. Given the heterogeneity of symptoms, components
of the treatments were customized to the participants based on what subgroup they
were classified into at the baseline examination. Customized rehabilitative care differen-
tiated by subgroups is outlined below:
Moser et al. BioMedical Engineering OnLine (2025) 24:48 Page 11 of 15

● Autonomic group—participants received 30 min of supervised progressive sub-

symptom aerobic exercise, as well as 20 min of mindfulness-based training twice
per week. Sub-symptom aerobic exercise training was defined as any form of aero-
bic exercise the participants were able to perform at a prescribed target heart rate
without causing a greater than a three-point change in total symptoms as rated on
an 11-point pain numerical rating scale (0–10). The prescribed target heart rate was
determined by the BCTT. Their target heart rate was 85–90% of their heart rate level
when they failed the BCTT. This test was done weekly to ensure the timely advance-
ment of the target heart rate while participants’ rehabilitation and recovery pro-
gressed. Participants were also instructed on various mindfulness-based techniques
they could perform at home; however, in the clinic twice per week, a box-breathing
technique was utilized. Outside the supervised rehabilitation sessions, participants
were instructed to perform 30 min of sub-symptom aerobic exercise three times per

● Cervical group—participants received bi-weekly physical therapy to the cervical

week [20, 21] as well as 20 min of mindfulness-based training daily [34].

spine. Physical therapy included soft tissue therapy directed to the cervical myofas-
cial tissues and graded cervical spine facet mobilizations and/or high velocity low
amplitude cervical manipulation. Participants also received supervised 20 min of
progressive neck isotonic strengthening exercises. They were also instructed to per-
form 20 min of general neck stretches, range of motion exercises and neck strength-

● Vestibulo-ocular group—participants received bi-weekly customized oculomo-

ening exercises twice a week outside the supervised sessions [20, 21].

tor, vestibular and balance exercises including adaptation exercises, gaze stability
exercises, visual–vestibular integration exercises, habituation exercises and static and
dynamic balance exercises. They were also instructed to perform daily 15–20 min of
customized vestibular and oculomotor exercises based on their clinical exam outside
the supervised sessions [20, 21].

In cases where participants demonstrated multiple impairments on the standardized

examination they received the listed treatments provided to the subgroups under which
they were classified. However, the frequency (twice per week), duration (6 weeks) and
length of care (60 min per session) did not change regardless of subgroup determination.
Lastly, participants were asked to refrain from seeking additional therapy. If they
undertook additional therapy outside of the trial, they were asked to document the
modality and frequency of said therapy in the provided treatment adherence calendar.
The adherence calendar was given to all participants at the start of the trial in order to
assist them with logging their daily rehabilitation. At the end of the 6 weeks, participants
returned the calendar and their adherence to the rehabilitation was examined.

Outcomes
Primary outcome
Participants’ overall symptomatology was evaluated with the Rivermead Post-Con-
cussion Symptoms Questionnaire (RPQ). The RPQ is a subjective questionnaire com-
posed of 16 concussion symptoms rated by patients according to their severity. For each
symptom, patients rate the severity on a 0–4 point scale. The symptoms are categorized
Moser et al. BioMedical Engineering OnLine (2025) 24:48 Page 12 of 15

as physical, cognitive, and emotional. It has been demonstrated that when the entire
16-item questionnaire is summated together there is a poor overall fit to the Rasch
model, suggesting all 16 items do not tap into the same underlying construct [10]. There-
fore, the questionnaire should be split into two; the RPQ-3, which scales early post-
concussion symptoms (headaches, dizziness and nausea) and the RPQ-13, which scales
symptoms associated with having a greater impact on participation, psychosocial func-
tioning and lifestyle. The RPQ-3 is scored 0–12 and the RPQ-13 is scored 0–52, with a
higher score representing a greater impact [11]. The RPQ-3 has shown moderate test–
retest reliability and the RPQ-13 has shown good test–retest reliability, with each form-
ing a unidimensional construct for patients with head injury at three months post-injury
[10, 11].

Secondary outcomes
The secondary outcome measures included the Patient Health Questionnaire-9 (PHQ-
9), the Neck Disability Index (NDI), and exercise tolerance.

Patient health questionnaire‑9 (PHQ‑9)

There is preliminary evidence to show that the presence of depression is a poor prognos-
tic factor for recovery in patients with persistent concussion symptoms [35]. As such,
a screening form for depression severity was measured via the PHQ-9. The PHQ-9 is
a 9-item questionnaire. It is a multipurpose instrument for screening, measuring and
monitoring the severity of perceived depression. The tool rates the frequency of the
symptoms, which factors into the scoring of the severity index with a higher score repre-
senting a greater perceived symptom severity ranging from 0 to 27. The PHQ-9 score is
interpreted as 0–4, minimal depression; 5–9, mild depression; 10–14, moderate; 15–19,
moderately severe depression; 20–27, severe depression [36–39]. The PHQ-9 has been
shown to have adequate reliability and good validity for the concussion population as
well as the spinal pain population [36–39].

Neck disability index (NDI)

Neck-related disability was measured via the NDI. The NDI is a 10-item questionnaire,
which examines the impact of self-reported neck pain on various activities of daily liv-
ing. The responses are summed for a total ranging from 0 to 50 with a higher score
representing a more severe perceived disability. Benchmark interpretations have been
suggested to include: 0–4, no disability; 5–14, mild disability; 15–24, moderate disability;
25–34, severe disability; and scores above 35, complete disability [40]. The questionnaire
has demonstrated reliability, construct validity and responsiveness to change in various
populations [40].

Exercise tolerance
Exercise tolerance was assessed via the BCTT. The BCTT is a well-established aerobic
exercise test designed to assess exercise tolerance, specifically to assess a patient’s heart
rate threshold [9]. BCTT has shown clinical utility in identifying those likely to suffer
persistent symptoms and the test is an excellent guide for exercise prescription follow-
ing a concussion [12, 41, 42]. Intolerance to exercise was defined as a failed BCTT. As
Moser et al. BioMedical Engineering OnLine (2025) 24:48 Page 13 of 15

defined by Leddy et al. [9], this was said to occur when a patient was unable to tolerate
exercise at a heart rate threshold predicted for one’s age due to the exacerbation of their
persistent concussion symptoms [9]. We specifically examined the change in heart rate
threshold at baseline and at the 6 week follow-up.
The primary and secondary outcome measures were examined at participants’ enroll-
ment (baseline) and following the 6 weeks of rehabilitation (trial end-point).

Statistical analysis
Descriptive statistics were applied to all outcome measures to assist in summarizing the
results. To examine for change in the primary and secondary outcome measure post-
intervention, statistical inferences were applied using a paired t-test and parameter esti-
mations with a significance level of p < 0.05.
The primary outcome is a change in symptoms following rehabilitative interventions
using the RPQ divided into the RPQ-3 and RPQ-13. Previous research examining the
internal construct validity of the Rivermead Post-Concussion Symptom Questionnaire
suggested that a rating of two or higher on at least three of the total 16 symptoms rep-
resents an unfavorable outcome [43]. As previously noted, unfortunately to date no vali-
dated change scores exist, thus we prescribed a cut-off of 15% improvement as minimal
clinically important difference (MCID). This translates to a change of two points on the
RPQ-3 and a change of eight points on the RPQ-13. This agrees with prior clinical litera-
ture examining changes post-intervention on concussion symptoms [13].
All unintended effects, harms and/or dropouts during the program were recorded.

Abbreviations
RPQ Rivermead post-concussion questionnaire
MCID Minimum clinically important difference
PHQ-9 Patient health questionnaire
NDI Neck disability index
TBI Traumatic brain injury
mTBI Mild traumatic brain injury
BCTT​ Buffalo concussion treadmill test

Author contributions
NM: Conceptualization, Methodology, Preliminary analysis, Investigation, Writing—Original Draft, Writing—Review and
Editing, Visualization MP: Conceptualization, Writing—Review and editing, Supervision SKR: Conceptualization, Writing—
Review and editing, Supervision.

Funding
The authors disclose NM as part of his doctoral program has received a Mitacs Accelerate grant with NeuroCatch as the
private sponsor for the support of the research.

Availability of data and materials

The used dataset can be made available upon request from the corresponding author.

Declarations
Competing interests
The authors declare no competing interests.

Received: 17 September 2024 Accepted: 7 April 2025

Moser et al. BioMedical Engineering OnLine (2025) 24:48 Page 14 of 15

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