4. Discussion

PCS patients are characterized by their heterogeneity and the syndrome is in many ways used as an umbrella-term for several complex and overlapping physiological and psychological pathologies. When examining the cases we found that, while having had similar experiences, they had different primary symptoms, different concerns and varying degrees of emotional and physical debilitation. Some researchers have argued that dividing PCS into various subcategories, or so called ‘post-concussion disorders’, could be used to improve outcomes and better treat underlying causes.28,57–59 Others have suggested the use of the RPQ, with additional questionnaires, as a possible classification system.60 While categorizing the cause and effect relationships remains important in advancing the treatment of PCS, the exact mechanisms between symptomatology and pathology is still unclear. Bearing this in mind, there is a need for a rehabilitation that is multifaceted, explorative and tailored to the individual.4 To further reflect on this process, the following section will examine the nature of PCS pathology and rehabilitation through the lens of the EBD model, while contextualizing our cases.

4.1 Best Research Evidence

Dysfunction of the ANS, or dysautonomia, acutely following a mTBI has been linked to symptoms of exercise intolerance, lowered tolerance to mental and physical stimuli, decreased cognitive ability, increased stress response and emotional dysfunction.28,61,62Prolonged dysautonomia is prevalent in the PCS group, with a recent review finding at least one form of autonomic dysregulation in the majority of patients.27 Evidence shows that the ANS plays a central role in psychological well-being63–65and that declining mental health after a mTBI is unfortunately a common occurrence,35,66 with PCS patients demonstrating higher incidence rates of both depression and anxiety compared to controls.67,68 Our cases reported an inability to deal with large crowds and various degrees of anxiety, frustration, worry or depression as well as reduced tolerance to external stimuli contributing to social isolation. This is in line with what is often observed in the clinical practice where many PCS patients will abstain from social activities to prevent symptom exacerbation. This abstinence functions as a negative feedback loop creating further withdrawal and worsening symptoms. Considering that prolonged social isolation is linked to poor mental health outcomes in the general population,69,70it is not entirely clear to what extent the relationship with PCS is causal or correlated. Furthermore, depression and anxiety might be risk factors for initially developing PCS.71,72 Yet, studies on rodents have found evidence of causality, in which induced mTBI disrupts limbic system function, subsequently leading to long lasting depressive, fearful and anxious behavior.73–75 Whatever the case, the neuropsychological nature of PCS makes providing psychosocial coping strategies a viable part of the multidisciplinary approach, and some reviews have supported the use of cognitive behavioral therapy in improving psychosocial outcomes76; however, more research is needed.
Meditation and mindfulness,77–80 body awareness therapy,81–83 breathing exercises and stretching,84,85 have shown to be effective ways of modulating the ANS, lower sympathetic activity and improve biomarkers of stress in various populations. Little evidence exists on treatments specifically addressing dysautonomia as a result of mTBI, although one pilot study did show improvements in QOL and self-efficacy on a group of PCS patients after undergoing a mindfulness-based intervention.86 Moreover, studies show that meditation can improve cognition and regulate CBF,77,87 making it an area of interest considering that CBF disruptions are linked to mTBI and PCS symptomatology.24,88 The efficacy of meditation techniques and body awareness strategies can vary between individuals89 and some techniques can be harder to conceptualize than others, which was illustrated by Case 3 who expressed difficulty in this regard. Our modified BBAT intervention in Study B was directed at addressing the high arousal and stimuli intolerant state of our cases, hopefully modulating the ANS and reducing PCS symptoms. While both cases reported positive associations with the sessions, only Case 4 experienced symptom relief and significant improved QOL. Considering that the intervention lasted 3 weeks, a longer duration of exposure may have been required to more accurately assess the protocol, as a duration of up to 8 weeks has been necessary before experiencing the full benefits of similar methods.90
Exercise intolerance is a common phenomenon in PCS patients and all of our cases reported having experienced symptom exacerbation during physical activity. Studies have found increased blood pressure (BP), HR and arterial CO2 in PCS patients compared to healthy controls during exercise, which may be linked to the changes in CBF and a reduced ability of the ANS to regulate orthostatic BP.22,91,92This exercise intolerance occurs at different ranges of HR and while finding the appropriate range for the individual can be challenging, abstaining from exercise and physical activity entirely is not recommended.92 Both cases in Study A showed a significant decrease in their PCS symptoms post-intervention and were ultimately able to increase their HR intensity, relative to their maximum HR, during exercise by 15% and 12%, for Case 1 and 2 respectively, without symptom exacerbation. However, as the cases simultaneously underwent cervical treatment, it is not possible to isolate the results of the exercise intervention completely. Yet our findings are in line with other studies showing improvements in physiological exercise biomarkers and PCS symptoms using similar protocols.59,91,93 This may be partly due to changes in CBF, as a pilot study, using fMRI, found that PCS patients had a normalization of brain activity and CBF after the implementation of a submaximal aerobic intervention.94 An important aspect of the protocol is keeping intensity levels below symptom threshold, before gradually increasing the intensity while assessing individual response. Early initiation of aerobic exercise has been associated with a faster recovery95; however, overexertion at different stages post-mTBI can be detrimental15,96–98and some evidence suggests that the appropriate intensity is timing-based.99 It is therefore recommended that practitioners monitor progress under controlled conditions and with the proper testing tools. A high quality and specifically developed method for testing this is the Buffalo Concussion Treadmill Test,100 but other testing methods with comparable protocols could be similarly applied.
Whiplash is commonly associated with PCS and exists both as part of the symptomatology, as well as a comorbidity. It has similar injury biomechanics to mTBI, such as the abrupt acceleration and deceleration of the cervical spine and head, and shares a majority of symptoms.101 One of the underlying mechanisms behind this may be cranial nerve trauma, including the vagus nerve which regulates the ANS,102,103 either as a direct result of impact, or as a secondary effect based on changes in arthrokinematics and joint degeneration.104,105 Cervical trauma has been linked to oculomotor deficiencies32,106,107 and whether as a result of whiplash or otherwise, issues with convergence, accommodation and saccades occur regularly after mTBI and often lingers in patients with PCS.19,108 Screening for this, and possibly referring to neuro-ophthalmologic treatment, is recommended.109
All our cases reported cervical stiffness and pain, and evidence shows that a high prevalence of various cervical and periarticular impairments are common after a mTBI. These include postural imbalances, myofascial triggers, muscle weakness, decreased joint mobility and weakness of cervical flexors associated with cervicogenic headaches.110,111 Considering this, and that up to 50% of whiplash patients still report symptoms a year after injury,112 cervical pathology is a critical consideration in the PCS rehabilitation.113–115 Both cases in Study A reported reductions in cervical associated symptoms such as dizziness, nausea, and headaches, although only Case 2 improved in CCFT grading. These findings are inconclusive, but other studies have suggested that deep flexor strengthening can have a positive effect on neck-related issues in some PCS patients114 and that cervical and vestibular rehabilitation may reduce cervicogenic symptoms.116,117 A variety of manual treatments may also improve outcomes, however, efficacy seems highly individual and more research is needed.113,118 Clinically, some PCS patients are sensitive to cervical treatment and may respond with symptom exacerbation to mobilizations, manipulations, strengthening exercises and even stretching.

4.2 Clinical Expertise

When initiating the PCS rehabilitation, identifying potential physical and mental barriers to activity, and acknowledging these limitations, is an important part of the planning. The process requires submaximal testing and treatment, and a deliberate slow progression as symptom thresholds are often low in the early stages. By taking inspiration from other chronic pain protocols, a proper pacing strategy can be useful in building tolerance to the treatment,119 and using positive reinforcement and education on the nature of PCS can help demystify the condition. This includes focusing on solutions and brain plasticity instead of limitations when communicating with the patient, after the initial explanation on pathology, and may help avoid the unwanted nocebo effects that many chronic pain patients can be susceptible to.120,121 Setbacks and symptom volatility are to be expected even with thoughtful consideration to programming, which is why the practitioner benefits from listening to the patient and adjusting volume and intensity accordingly, as well as including an appropriate frequency of examination and re-testing. Working on acceptance of current disability may help improve emotional outcomes and patient self-efficacy,122 and celebrating short term goals helps improve patient motivation and long term compliance.123,124 Lastly, a key part of administering the rehabilitation is knowing when a referral is indicated and if treatment is outside the bounds of expertise of the practitioner.

4.3 Patient preferences

PCS is in many ways a “hidden condition” not easily visible and with no current standardized biomarkers for diagnosis,125and the path towards rehabilitation is often confusing, and uncertain, for patients and practitioners alike. Most general practitioners are not well equipped to treat PCS patients, which is highlighted by the lack of standardized care, and rest is often the only offered treatment strategy. Our cases expressed dissatisfaction with their healthcare providers and felt neglected, as well as not having been taken seriously. One of the emerging themes derived from the cases was the importance of meeting other patients in similar circumstances who could relate to them and inhabit an acknowledging space to freely share experiences and discuss daily obstacles. This acknowledgement and social exchange was seen as a central part of coping with the condition, and should be viewed by practitioners as a legitimate consideration for rehabilitation in the clinical practice. The use of deliberate framing and the facilitation of a constructive and accommodating environment in our studies were beneficial in dealing with the psychosocial challenges. Cases further highlighted that being in a safe environment, and adjusting for unwanted mental and physical overstimulation, resulted in less exacerbation of symptoms. Besides the benefits of rehabilitation on their mood, stamina and cognitive function, our cases expressed a sense of meaning in their daily lives when having something to attend, especially considering that three of the cases were on sick leave, with none regularly engaging in scheduled social events. The interventions themselves were seen as motivating factors, regardless of any improvement in symptoms, suggesting that an active approach has an inherent advantage compared to a passive or non-active approach even before considering outcomes. Through the gathering of the qualitative data, including the group feedback sessions, our cases helped clarify valuable areas of concern illuminating patient preferences and individual perspectives on the intervention protocols which would not have been possible otherwise.

4.4 Model of Conclusion

By taking advantage of the three dimensions of the EBP model as a methodological approach to the PCS cases, this paper incorporated the: Best Research Evidence, Clinical Expertise and Patient Preferences, through an examination of the benefits of two distinct intervention protocols. These results illustrate how an active and individualized approach can represent important qualities that can be applied into further and larger studies, and we recommend additional studies regarding exposure to active, individualized and graded treatments to patients dealing with PCS. Based on the results and discussion in this paper, we have summarized relevant findings and suggestions in the following modified EBP model (Fig. 7), which may be of help to practitioners in the clinical practice.
FIGURE 7