Scientific and practical relevance of the project
Neurological damage acquired through stroke, traumatic central nerve injury or traumatic brain injury (TBI). The resulting sudden loss of independence often leads to irreversible harm and is one of the main causes of lifelong support and home care needs. Strokes cause a high economic and health burden [1]. For example, the cost of stroke to healthcare systems in 32 countries totalled €27 billion in 2017 [2]. This is why the Stroke Alliance for Europe (SAFE) emphasizes the need for European countries to invest in cost-effective stroke interventions to improve rehabilitation and the quality of life for stroke survivors [2]. The number of TBI patients in 2016 in Germany was 419,507 [3]. More than 4,000 patients become long-term care cases due to severe permanent injuries, resulting in high costs and limited ability to work [4]. The rehabilitation process of neurological diseases is highly complex, depends on numerous influencing factors and is vague concerning the results [5]. Functional, cognitive and psychological challenges directly impact the ability to perform daily tasks independently [6]. Acquired neurological damage leads to a loss of social roles for those affected and requires adaptation to the new living conditions [7]. In the context of illnesses the individual coping strategies employed vary greatly across the different patients [8]. Life orientations, goals, ideas, and expectations about one's own life and future development represent a relevant aspect of rehabilitative cooperation and success. Relatives of those who are directly affected not only experience trauma but also deal with the illness and its lasting personal consequences for themselves [9]. Individual processes take place within partnership dyads and domestic cohabitation. This is particularly relevant for Germany where 63% of people in need of care are cared exclusively by relatives in a domestic setting. Nursing homes care for only 16% of people in need of long-term care in Germany [10].
Family change processes and relationship dynamics
In the partnership dyad between the person affected and the caregivers, dual roles arise as spouse, patient or caring relative [11]. Changes caused by a sudden loss of independence and the need for assistance due to a family member's illness impact power dynamics, role distributions, tasks, and decision-making between patients and their relatives. On the one hand, relatives provide their resources. On the other hand, they need help themselves. Within the framework of the existing family system, relatives thus have to face new challenges [9, 12]. In this context, the rehabilitation process after acquired neurological damage is associated with fears, worries and adaptations for many patients and their caregivers [13].
The therapeutic relationship significantly influences the rehabilitation process of neurological diseases and is of paramount importance [14, 15].
Family caregivers play a central role in providing care, therapy and social support, particularly in the case of lifelong disability due to acquired neurological damage [16]. According to recent international Studies, the effects of neurological damage are according to recent international studies, the psychosocial effects of neurological damage have already been described for patients [12, 17] and for family caregivers of affected persons [18]. Studies also explore the dynamics between patients and therapists, as well as the relationships formed in patient-therapist interactions [12, 19] . However, given the importance of biopsychosocial aspects in therapy and the close interactions affecting the well-being of patients and their relatives, there is a lack of studies on the influence of health professionals on the dyadic relationship between patients and relatives in different phases of rehabilitation.
Our study addresses the following questions:
1) What influence on the dyadic relationship do affected persons and their life partners attribute to the professional caregivers?
2) How does the dyadic relationship between persons with acquired central nervous chronic impairment and their significant others change over time and what does it mean for the therapeutic process?
3) How do relationships and relationship aspects influence the rehabilitation process?
Furthermore, we discuss how professional caregivers should react to the different constellations in the rehabilitation process to enable the best possible quality of life from the perspective of the person affected and their life partner.
Underpinning theories and theoretical approach
The theory of symbolic interactionism (SI) is based on the fundamental idea that actors influence each other within the framework of interaction processes and the resulting ongoing interpretations [20]. In relation to the object of study, this means that two people enter a relationship with each other based on a "self" resulting from their history of interaction. The "self" is called into question by the sudden injury that leads to a long-term need for help, is no longer connectable in the strongly changed interaction, and needs a challenging adaptation.
Building on the understanding of SI, Leslie Baxter's Relational Dialectics Theory (RDT) focuses on forming meaning between relationship partners [21]. The relationship between patient and caregiver is established in dialogue and is subject to continuous change. Examples of dialectics within the dyadic relationship are integration-separation, stability-change, or expression-non expression. According to the RDT, these dialectics are natural and unavoidable in any relationship, and they play a crucial role in shaping how individuals communicate and interact [22]. This is particularly relevant to understand the changes within the couple relationship of patient and relative overtime.
From a theoretical perspective, the study aims to increase the knowledge on the influence of changes in the couple relationship on the rehabilitation process and vice versa, and consequently on the quality of life of patients and caregivers. Different types of patient-caregiver dyads can be identified and empirically validated based on theoretical approaches. This approach makes it possible to link empirically identified types back to the theory of symbolic interactionism [20], and the RDT [21], to support them empirically or to change, refute or expand them. A major novelty of the study lies in the theoretical foundation of the reciprocal effects of relational changes in acquired central nervous damage in rehabilitative processes and in interaction with health professionals.
From a practical perspective, standardised types of dyads can be recognised, and various rehabilitative approaches can be postulated at the practice level on a social-psychological basis. This enables the enhancement of individual care for affected individuals, with a focus on improving their quality of life.