Dizziness and localized pain are often concurrent in patients with balance or psychological disorders

1 Introduction

While acute dizziness often is associated with vestibular deficits or of central nervous system (CNS) origin, the etiology of longstanding complaints of dizziness often cannot sufficiently be explained by such pathology alone. When vestibular deficits remain, the CNS is often able to compensate for the reduced or asymmetric vestibular activity with other sensory input, such as proprioception and vision [1]. Dizziness might also be caused by too enhanced sensitivity to one specific sensory input [2], central or peripheral sensitization [3] and hypervigilance [4]. When dizziness persists without findings of significant vestibular or central deficits, the remaining symptoms are often classified as persistent postural perceptual dizziness (PPPD) [5], phobic postural vertigo [6] or cervicogenic dizziness [7]. Patients with pronounced dizziness and a concomitant psychological disorder exhibit to a higher degree no pathological vestibular findings, and seem more vulnerable in contexts with conflicting vestibular, proprioceptive and visual information by suffering from adaptation deficits in using sensory reweighting [8], [9]. These patients often use a postural control strategy with markedly more high frequency sway, i.e. a strategy that is prominently both energy consuming and demanding for the musculoskeletal system [10].

That persistent dizziness may cause perceptual and emotional consequences is well-established [5], [11], [12], [13], [14]. However lately, additional central mechanisms, well known in the field of persistent pain [15], [16], has been suggested to be active also in dizziness contexts [3], [17]. Such mechanisms might enhance and prolong impairments and subsequently make single diagnoses and measures less useful. When musculoskeletal disorder, dizziness and psychological issues coincide, it is thus challenging to derive cause, consequence, amplifications and maintenance factors. Pain conditions has to date sparsely been regarded as a possible contributing and enhancing factor for persistent dizziness, except for patients suffering from cervicogenic dizziness, a concept derived from somatosensory theory [18], [19], [20]. The postural control system is however indisputable a complex system where vestibular, visual and proprioceptive information interact at different peripheral and central levels, in processes that includes perceptual interpretations and biomechanical preconditions [21], [22], [23]. Therefore, it seems appealing to consider different symptoms such as dizziness, psychological disorder and pain as multifaceted, interacting and interfering entities rather than as separate insusceptible issues. Patients suffering from some of these different impairments most probably seek healthcare within, or are referred to, the most liable discipline for the single most prominent and disabling symptom. Hence, information about comorbidity and mutual maintenance factors might not be noticed and consequently not addressed properly by healthcare providers unless the patients report their complete medical history.

The study aim was to explore the existence of pain in patients referred to a vestibular unit for balance disorders and in patients referred to a psychiatric outpatient clinic for psychological treatment of anxiety or depressive disorders. Another aim was to investigate whether the occurrence of pain at certain locations coincided with symptoms of dizziness and caused functional, physical and emotional consequences.

2 Materials and methods

3 Results

3.1 Determining the role of pain location

3.1.1 Pain distribution when sorted in different factor categories

The balance population reported significantly more often pain in the arms compared with the psychological population (Fig. 1A). A trend suggests that patients in the balance population also suffered from more pain in the head.

Fig. 1:

Pain distribution patterns for: (A) each patient population; (B) each dizziness group; (C) the patients reporting pain; (D) the patients reporting a history of an accident and not having a history of an accident. The values on the x-axis denotes the percentage of the patients reporting pain with the pain localization on the y-axis. Note that a patient can report pain in more than one location. p-Values to the level of trend <0.1 are detailed.

The patients with dizziness reported significantly more often pain in the head, neck/shoulders, and feet compared with those who did not report dizziness (Fig. 1B). A trend also suggested more pain in the arms among those suffering from dizziness.

In the patients suffering from any kind of pain, the most common location for pain were the head (45.6%), the neck/shoulder (85.3%), the back (69.1%), and the legs (35.3%) (Fig. 1C).

The patients reporting that they had an accident in their history had significantly more often pain in the head, neck/shoulder and in the arms compared with patients that had no history of an accident (Fig. 1D). A trend also suggested that those that had suffered an accident more commonly had pain in the back.

3.1.2 Influence of local pain on the GLM Anova main factors Patient population, Dizziness, Pain and Accident

The nouns with capital letters in the GLM Anova result presentation (e.g. Pain) reflects that the results presented relates to the role this parameter had as a main factor in the analysis.

The reported pain at the investigated locations were not significantly different between the two patient Populations (Table 2). Patients suffering from Dizziness had significantly more often pain in the neck/shoulder. Patients suffering from any kind of Pain had particularly strong relationships to pain in the neck/shoulder, in the back, in the legs and in the head. Moreover, patients that had suffered an Accident reported significantly more pain in the back. The main factor interaction Population×Accident reveals that patients in the psychological Population that had suffered an Accident had significantly more often pain in the lower torso. Finally, the main factor interaction Dizziness×Accident reveals that patients that suffered from Dizziness and had experienced an Accident significantly more often suffered from pain in the neck/shoulders and in the legs.

3.1.3 Association between Pain locations and Dizziness

The iterative pain distribution analysis using GLM Anova determined that the combination of pain locations, able to best describe when patients suffered from dizziness or not, was when the patient reported pain in either or both the neck/shoulder and in the back. Based on this result, the henceforth analysis of the consequences of pain will be limited to NSB pain (whether the patients reported pain in either of the Neck/Shoulder or the Back, or at both locations).

4 Discussion

When patients from two clinical populations, with balance respectively psychological disorders, were asked about symptoms of dizziness and pain the results suggest that experience of dizziness and NSB pain significantly often coincided within individuals across both clinical populations. Thus, if a patient suffers from dizziness, it is likely that this patient also suffers from NSB pain. Dizziness was reported, as expected, by most patients referred to the vestibular unit, but was also common in the psychological population.

Most patients reported that both their pain and dizziness had persisted for long periods, where the Balance population reported longer symptom duration than those with dizziness in the Psychological population (Table 4). The consequences linked to persistent dizziness have been reported to exceed those with acute dizziness [11]. Here, specifically the DHI emotional sub-scale values were found to correlate with reduced mood (Handicap and Depression Scale) [11]. Our results also suggest affected mood in DHI scores, with the highest scores in the emotional sub-scale, closely followed by the score in the functional sub-scale (Tables 4–7). The Balance population scored DHI higher, corresponding to moderate self-perceived handicap, compared to mild in the Psychological population [11], [30].

In the Psychological group, 61% reported dizziness. There are several psychological disorders coupled with dizziness. For example, dizzy symptoms are included in generalized anxiety disorders [30]. Patients with phobic features present enhanced sensitivity for vibratory stimulation, yet another example for the close interaction between balance, emotions and muscular activity [9]. However, single modality interventions is often not effective for patients suffering from persistent dizziness and concomitant emotional issues, because the symptoms of these patients often relapses [6], [31], which suggest that multimodal intervention as more appropriate in many cases [32].

NSB pain was reported significantly more often among the patients who reported dizziness and those patients stated significantly higher NSB Pain intensity and severity (Table 5), as well as higher DHI_Total and emotional sub-scale scores (Table 6). Thus, co-morbidity, with concurrent NSB pain probably contributes to additive emotional strain when dizzy. Patients, who reported a history of an accident linked to their NSB pain presented findings supporting earlier studies, suggesting that neck pain often coincide with dizziness and balance impairment after whiplash trauma [33], [34], [35].

However, the burden of co-morbidity might not be the only factor explaining the results. A NSB pain-induced distorted proprioception might also be a contributing factor for dizziness [16], [36], [37]. Hence, an initial NSB pain might cause distorted cervical proprioceptive information and produce a sensory mismatch that induce or maintain conditions such as dizziness and emotional issues. However, reciprocal processes can also exist, i.e. initial dizziness and emotional issues can induce muscular tension and thus NSB pain. Our results cannot corroborate an explicit causal relationship between symptoms. Our findings though imply a bi-directional relationship between appearing symptoms, e.g. different patients reported either the NSB Pain or dizziness to appear as first symptom followed later by secondary symptoms of dizziness and NSB Pain, respectively. These findings elucidate the relevance of attention and awareness to different additional symptoms occurring progressively. Since dizziness, pain and emotional issues often coincided, these symptoms might enhance and add sensitization processes with prolonged suffering [38]. Such mechanisms can derive from several factors spanning the spectrum from distorted muscle spindles [36], [39], [40], central re-organization and habituation [3], [8], [41], emotional state (e.g. anxiety, depression) [42], cognitive processes and the overall perception of loss of health [43]. Central mechanisms and distorted habituation pattern have been suggested as being a part of persistent dizziness [3], and the theories about sensitization processes suggest different additive factors when dizziness persists [3], [5], [11], [41].

Our results validate the complexity of postural performance, sensorimotor control, perception, cognition and emotions, based on direct analysis of clinical population data [38]. Hence, it seems that different symptoms can occur in parallel, with or without any obvious relationship, and therefore need to be handled accordingly and in account of all symptoms. The results, thus, advocate a multi-modal symptom-mapping, sometimes accompanied with a multi-professional intervention, as the most likely successful approach [32].

To conclude, this study suggests that there might be an interaction between persistent dizziness, emotions and NSB pain by comorbidity, with mutual maintenance and additive effects. Thus, symptoms such as persistent dizziness should be considered multifactorial [44] and handled accordingly. The idea about mutual maintenance and additive effects between different symptoms might bring optimal intervention options for population groups that suffer from concurrent persistent dizziness, mental issues and NSB pain. In light of our results, there seems to be an obvious risk of having a too small “receptive scope” of symptoms in clinical context, both from the patients’ and the clinicians’ point of view. Hence, if the clinician do not ask for comorbidity, then valuable information might be lost when determining the best clinical management [31].