Abstract
Purpose
The study sought to evaluate the longer-term effects of a brief cognitive behavior therapy (CBT) intervention for patients with chronic subjective dizziness (CSD). In addition, it sought to identify predictors of longer-term disability in this group.
Materials and methods
Forty-four patients with CSD referred by a neuro-otological clinic were followed-up six months after completing a brief treatment program based on the CBT model of panic disorder. Patients completed the following measures: Dizziness Handicap Inventory, Depression, Anxiety and Stress Scales, Dizziness Symptoms Inventory, and the Safety Behaviours Inventory. Measures were completed at pre and post-treatment, as well as at one and six months post-treatment.
Results
Treatment gains observed immediately after treatment were maintained at one and six months post-treatment. High levels of pre-treatment anxiety predicted higher levels of disability at six months post-treatment. Duration and severity of dizziness, and medical or psychiatric comorbidity did not predict disability at six month follow-up.
Conclusions
A brief CBT intervention for patients with CSD produced improvements in physical symptoms, disability, and functional impairment which were sustained at one month and six months post intervention. Patients with high levels of anxiety prior to treatment had higher levels of disability at six months post-treatment. It is possible that more focused interventions that specifically target anxiety might produce further benefits for this cohort.
1
Introduction
Dizziness is a common and chronic symptom in the general community and has been associated with significant handicap . Multiple studies have found a relationship between dizziness and psychiatric symptoms, particularly symptoms associated with anxiety disorders . For some, anxiety disorders are seen as the primary cause of the dizziness, while for others, neuro-otolgical conditions are thought to exacerbate pre-existing psychiatric disorders or trigger new ones . Regardless of the etiology, dizziness that is perpetuated by anxiety has been frequently observed, and has been referred to as psychogenic dizziness , postural phobic vertigo , and chronic subjective dizziness (CSD) . Possible psycho-physiological pathways have been speculated on .
Within this population treatments with selective serotonin reuptake inhibitors (SSRIs) produce benefits , however non-response and intolerance due to side-effects are in the order of 25 to 33% . Vestibular rehabilitation (VR) has also been shown to reduce symptoms in many patients . In the last decade psychological treatment using cognitive behavior therapy (CBT) has also been reported. As CBT is an effective treatment for anxiety disorders , it has potential application in the treatment of anxiety-related dizziness. Two Swedish studies that evaluated CBT combined with VR in this patient cohort found improvements in the treatment group relative to the waitlist control (including greater physical abilities and reduced disability) in the immediate post-therapy period. However the relative contribution of CBT versus VR was unclear, and follow-up data were not collected. Another study evaluated an 8–12 session CBT intervention relative to a self-administered VR program. CBT was associated with greater reductions in anxiety, depression, and reported handicap in the post-therapy period. These improvements were not sustained at 12 month follow up . In a recent study by Edelman, Mahoney, and Cremer , a three-session CBT intervention was shown to produce significant reductions in dizziness symptoms, disability, and functional impairment in the immediate post-therapy period, relative to waitlist control.
There are some, albeit limited data available on longer-term outcomes of treatments for patients in this category. In trials of SSRIs, treatment gains have been reported to be maintained at two to three months post-treatment , 12 months post-treatment , and 16 to 36 months post-treatment . Brandt and colleagues reported that over 70% of patients who had received a 2–3 session psychological intervention between six months and 5.5 years post-intervention and between five years and 15 years post-intervention had either resolution or substantial reduction in symptoms at follow-up. However, no immediate post-therapy data were collected and no control group had been used. The intervention had comprised an explanation of the underlying mechanisms contributing to symptoms, reassurance, encouragement to do regular physical activity, and to use repeated exposure to situations that provoked dizziness. While not specifically labeled as CBT, the description suggests many aspects in common with the CBT approach used by Edelman and colleagues .
The current study sought to determine the effects of a brief CBT intervention (see Edelman et al. ) on physical and psychological symptoms, disability, and functional impairment in patients with CSD, at one month and six months post-treatment. We hypothesized that improvements in symptoms, disability, and functional impairment made in the immediate post-treatment period would be maintained at one and six month follow-up.
The study also sought to identify predictors of disability at six months post-treatment, as this information might lead to better understanding of the disorder and how treatments might be improved. Previous studies have identified a variety of predictors. Brandt and colleagues found that shorter duration of illness was associated with better longer-term outcomes, although some patients with the longest illness duration still made considerable improvements. Staab et al. found that illness duration was not related to treatment response to SSRIs. However it was associated with degree of response, with shorter illness associated with higher likelihood of a very much improved status post-treatment. In addition, patients with central nervous system deficits had poorer post-treatment outcomes compared to those with coexisting peripheral vestibular conditions or migraine headaches, or those whose only diagnosis was a psychiatric disorder. The presence of major psychiatric disorders alone did not predict treatment response. Finally, studies that did not involve treatment, but which examined factors related to longer-term disability in patients with dizziness, have identified the presence of three or more chronic health problems, illness duration of more than one year, high anxiety levels and activity limitation due to illness , a history of fainting, vertigo, and avoidance of dizziness provoking situations as significant predictors.
Based on previous research we hypothesized that that duration of illness, co-morbid psychiatric and medical conditions, and the severity of pre-treatment symptoms of dizziness, anxiety, and avoidance would predict disability at six months post-treatment.
2
Method
2.1
Participants
Participants were 44 consecutive patients referred by a neuro-otological clinic for psychological assessment and treatment of medically unexplained dizziness, that is dizziness which persisted despite appropriate treatment or dizziness which was experienced beyond that expected given participants’ current diagnosis. Participants were predominantly (72.7%) female with mean age of 46.7 years ( SD = 12.97). The diagnostic composition included Benign Paroxysmal Positional Vertigo (BPPV, 25.0%), presence of prior rotational vertigo episodes without definitive diagnosis (29.5%), migrainous vertigo (13.6%), Ménière’s disease (4.5%), labyrinthitis (4.5%), and no history of vertigo or vestibular pathology (22.7%). Prior to referral for psychological assessment, participants with definitive vestibular pathology were treated appropriately (e.g., patients with BPPV were successfully treated with a canalith re-positioning maneuver) but continued to experience dizziness. The duration of dizziness in this sample ranged from one to 240 months (median = 8.5 months), with four participants reporting a previous period of dizziness (duration range 2–48 months).
With respect to psychiatric diagnoses, 43.2% met criteria for generalized anxiety disorder, 36.4% for major depressive disorder, 38.6% for panic disorder, 6.8% reported dysthymia, and 2.3% reported social phobia. Nine participants (20.5%) did not meet criteria for any psychiatric disorder. Among patients who met criteria for a disorder, the number of diagnoses per patient ranged from one to four ( M = 1.63, SD = .84).
2.2
Measures
2.2.1
Mini International Neuropsychiatric Interview (MINI)
The MINI is a structured diagnostic interview for psychiatric diagnoses as described in the Diagnostic and Statistical Manual (DSM-IV) . Reliability and validity have been demonstrated . The anxiety and depression modules were administered shortly after recruitment.
2.2.2
Dizziness Symptoms Inventory (DSI)
The DSI is a measure of the severity of dizziness and associated physical symptoms developed and used by Edelman, Mahoney, and Cremer . Items on this inventory were based on symptoms described by Staab , as well as further symptoms that were frequently observed in these patients. In this study, internal consistency (α = .81) was good.
2.2.3
Dizziness Handicap Inventory (DHI)
The DHI is a widely used and validated measure that assesses self-perceived disability associated with dizziness in three domains — functional, emotional, and physical. Internal consistency in this study was α = .89.
2.2.4
Safety Behaviours Inventory (SBI)
This 18-item descriptive measure was developed by Edelman et al. to assess the frequency of avoidance (e.g., driving, exercising, and socialising) and safety behaviors (e.g., take someone with me, walk close to the fence) related to dizziness. Current internal consistency was α = .90.
2.2.5
Depression, Anxiety and Stress Scales-21 (DASS-21)
The DASS-21 is a widely used and validated scale consisting of three subscales that measure symptoms of depression, anxiety, and psychological stress. The Anxiety subscale was used in this study (α = .71).
2.3
Procedure
The study was approved by St Vincent’s Hospital Human Ethics Committee. Participants were recruited from a specialist neuro-otological clinic and were randomized to immediate CBT treatment (n = 23) or to a waitlist treatment control group (n = 21). The waitlist treatment control group completed the CBT program four weeks after the immediate treatment group as part of an earlier randomized controlled trial (Edelman et al. ). The treatment protocol was identical for both groups. Treatment involved three weekly sessions and included psycho-education about dizziness, in-session behavioral experiments regarding the impact of attention on dizziness symptoms, exposure exercises aimed at reducing avoidance and safety behaviors, alternative strategies for responding to dizziness (e.g., attention refocussing and symptom ‘surfing’), and encouragement to resume normal lifestyle regardless of the presence of symptoms. All participants commenced and completed treatment. Participants completed self-report measures at recruitment, and at pre- and post treatment. Follow-up data were collected one and six months after treatment. (For full details of procedures see Edelman et al.) .
2
Method
2.1
Participants
Participants were 44 consecutive patients referred by a neuro-otological clinic for psychological assessment and treatment of medically unexplained dizziness, that is dizziness which persisted despite appropriate treatment or dizziness which was experienced beyond that expected given participants’ current diagnosis. Participants were predominantly (72.7%) female with mean age of 46.7 years ( SD = 12.97). The diagnostic composition included Benign Paroxysmal Positional Vertigo (BPPV, 25.0%), presence of prior rotational vertigo episodes without definitive diagnosis (29.5%), migrainous vertigo (13.6%), Ménière’s disease (4.5%), labyrinthitis (4.5%), and no history of vertigo or vestibular pathology (22.7%). Prior to referral for psychological assessment, participants with definitive vestibular pathology were treated appropriately (e.g., patients with BPPV were successfully treated with a canalith re-positioning maneuver) but continued to experience dizziness. The duration of dizziness in this sample ranged from one to 240 months (median = 8.5 months), with four participants reporting a previous period of dizziness (duration range 2–48 months).
With respect to psychiatric diagnoses, 43.2% met criteria for generalized anxiety disorder, 36.4% for major depressive disorder, 38.6% for panic disorder, 6.8% reported dysthymia, and 2.3% reported social phobia. Nine participants (20.5%) did not meet criteria for any psychiatric disorder. Among patients who met criteria for a disorder, the number of diagnoses per patient ranged from one to four ( M = 1.63, SD = .84).
2.2
Measures
2.2.1
Mini International Neuropsychiatric Interview (MINI)
The MINI is a structured diagnostic interview for psychiatric diagnoses as described in the Diagnostic and Statistical Manual (DSM-IV) . Reliability and validity have been demonstrated . The anxiety and depression modules were administered shortly after recruitment.
2.2.2
Dizziness Symptoms Inventory (DSI)
The DSI is a measure of the severity of dizziness and associated physical symptoms developed and used by Edelman, Mahoney, and Cremer . Items on this inventory were based on symptoms described by Staab , as well as further symptoms that were frequently observed in these patients. In this study, internal consistency (α = .81) was good.
2.2.3
Dizziness Handicap Inventory (DHI)
The DHI is a widely used and validated measure that assesses self-perceived disability associated with dizziness in three domains — functional, emotional, and physical. Internal consistency in this study was α = .89.
2.2.4
Safety Behaviours Inventory (SBI)
This 18-item descriptive measure was developed by Edelman et al. to assess the frequency of avoidance (e.g., driving, exercising, and socialising) and safety behaviors (e.g., take someone with me, walk close to the fence) related to dizziness. Current internal consistency was α = .90.
2.2.5
Depression, Anxiety and Stress Scales-21 (DASS-21)
The DASS-21 is a widely used and validated scale consisting of three subscales that measure symptoms of depression, anxiety, and psychological stress. The Anxiety subscale was used in this study (α = .71).
2.3
Procedure
The study was approved by St Vincent’s Hospital Human Ethics Committee. Participants were recruited from a specialist neuro-otological clinic and were randomized to immediate CBT treatment (n = 23) or to a waitlist treatment control group (n = 21). The waitlist treatment control group completed the CBT program four weeks after the immediate treatment group as part of an earlier randomized controlled trial (Edelman et al. ). The treatment protocol was identical for both groups. Treatment involved three weekly sessions and included psycho-education about dizziness, in-session behavioral experiments regarding the impact of attention on dizziness symptoms, exposure exercises aimed at reducing avoidance and safety behaviors, alternative strategies for responding to dizziness (e.g., attention refocussing and symptom ‘surfing’), and encouragement to resume normal lifestyle regardless of the presence of symptoms. All participants commenced and completed treatment. Participants completed self-report measures at recruitment, and at pre- and post treatment. Follow-up data were collected one and six months after treatment. (For full details of procedures see Edelman et al.) .
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