AFTER MILD TRAUMATIC BRAIN injury (TBI), 10% to. Outcome After Mild to Moderate Traumatic Brain Injury: The Role of Dizziness

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1 1662 Outcome After Mild to Moderate Traumatic Brain Injury: The Role of Dizziness Laury Chamelian, MD, FRCPC, Anthony Feinstein, PhD, MRCPsych, FRCPC ABSTRACT. Chamelian L, Feinstein A. Outcome after mild to moderate traumatic brain injury: the role of dizziness. Arch Phys Med Rehabil 2004;85: Objective: To assess the specific effect of dizziness on psychosocial outcome after mild to moderate traumatic brain injury (TBI). Design: Six-month cross-sectional study. Setting: An outpatient TBI clinic in a tertiary care referral center. Participants: A consecutive sample of 207 adults with mild to moderate TBI, 138 (66.7%) of whom had subjective complaint of posttraumatic dizziness. Interventions: Not applicable. Main Outcome Measures: Psychosocial indices (Glasgow Outcome Scale [GOS], General Health Questionnaire [GHQ], Rivermead Head Injury Follow-Up Questionnaire [RHFUQ], return to work status) were collected from dizzy and nondizzy patients. Results: Despite similar demographic, TBI, and global disability (GOS) profiles of both groups, psychosocial functioning (GHQ, RHFUQ, return to work) was significantly worse in dizzy subjects (P.01 for all indices). A logistic regression analysis identified dizziness (P.006), total GHQ (P.001), and psychotropic and analgesic use (P.05) as significant independent predictors of reemployment. Conclusions: Although dizziness was closely linked to psychologic distress at 6 months after head injury, it also emerged as an independent predictor of failure to return to work, suggesting that not all its adverse effects on outcome are psychologically mediated. Clinicians need to be alert to the presence of dizziness as an adverse prognostic indicator after mild to moderate TBI. Key Words: Dizziness; Head injuries; Rehabilitation; Psychosocial aspects by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation AFTER MILD TRAUMATIC BRAIN injury (TBI), 10% to 15% of patients remain symptomatic with postconcussive symptoms for a year or longer. 1 This figure rises to 28% for those who have sustained moderate head injury. 2 Possible reasons for poor outcome include biologic, psychosocial, and medicolegal explanations. 1,3-6 From the University of Toronto, Toronto, ON, Canada. Supported by the Canadian Institutes of Health Research (grant no ). No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors(s) or upon any organization with which the author(s) is/are associated. Reprint requests to Anthony Feinstein, MD, FG08, Sunnybrook and Women s College Health Sciences Centre, 2075 Bayview Ave, Toronto, ON M4N 3M5, Canada, antfeinstein@aol.com /04/ $30.00/0 doi: /j.apmr Persisting postconcussive symptoms are often responsible for considerable social distress because 34% to 75% 7,8 of TBI patients, depending on injury severity, fail to return to work 3 months after injury. At 1-year follow-up, only 80% of mild TBI 9 patients and 61% of those with moderate head injuries 10 are able to work. However, even though reemployment frequently occurs despite persistent postconcussive symptoms, these symptoms prevent patients from performing at their preaccident levels. 11,12 Several studies have identified distinct variables that predict poor vocational recovery after head injury. These are greater TBI severity (based on Glasgow Coma Scale [GCS] or duration of posttraumatic amnesia 15,16 [PTA]), absence of work before injury, 13,16,17 previous employment in semiskilled or unskilled jobs, 18 low educational level, 14,19 preexisting psychiatric condition, 20,21 comorbid problems with drugs and alcohol, and increased age. 13,17 However, thus far in the literature, little emphasis has been placed on the potential predictive value of postconcussive symptoms with regard to return to work, despite the persistent nature of the symptoms after head injury. For example, posttraumatic dizziness may affect 20% to 50% of patients with TBI, depending on injury severity, 23,24 and remain disabling for many months. 6,10,25,26 Regardless of its specific type and possible underlying cause, dizziness is among the top 5 postconcussive symptoms distinguishing patients with mild TBI from healthy controls. 27 Yet, its effect on outcome remains unclear because it is frequently analyzed along with other symptoms that are experienced after a head injury ,25,28 The single study that assessed specifically the prognosis for posttraumatic dizziness reported a 46% failure of return to work 5 years after mild to moderate TBI; however, a control group of nondizzy patients was not included, 24 thereby making data interpretation problematic. Given the paucity of research on posttraumatic dizziness, the methodologic limitations of previous studies, plus the fact that dizziness has been identified as among the more specific symptoms of TBI, we undertook a study to address what role dizziness plays in outcome after mild to moderate TBI. METHODS Participants Selection A consecutive sample of 207 patients was recruited from a TBI clinic at a large trauma centre. Mild TBI was defined as a GCS score of 13 to 15, PTA of less than 24 hours, and loss of consciousness (LOC) less than 20 minutes. 29 Moderate TBI criteria were a GCS score of 9 to 12 and PTA of more than 24 hours but less than 1 week. Recruitment was limited to patients aged 18 to 60 years and to those who had completed a selfreport questionnaire assessing the presence of posttraumatic dizziness on a 5-point Likert scale (0, absent; 1, no more than before the accident; 2, mild; 3, moderate; 4, severe). Subjects (n 138) with scores of 2 or more were deemed to have dizziness, whereas the nondizzy patients (n 69) had scored 0 or 1 on the self-report questionnaire.

2 DIZZINESS AND MILD TO MODERATE HEAD INJURY, Chamelian 1663 Table 1: Demographic and Premorbid Health Factors in Dizzy Versus Nondizzy Patients Background Dizzy (n 138) Nondizzy (n 69) t / 2 Tests P Mean age SD (y) t Gender (male) 60.1% 71.0% Marital status (single or divorced) 52.2% 68.1% Education (beyond high school) 42.3% 36.2% Employment (employed) 80.7% 72.5% Occupation (professional/semiprofessional) 14.8% 13.6% Past alcohol abuse 29.9% 30.4% Past substance abuse 13.2% 20.3% Prior TBI 22.6% 17.4% Past psychiatric history 14.7% 20.4% Family psychiatric history 30.4% 31.3% As part of the clinic s mandate, all patients are seen as soon after injury as possible. At that visit, demographic and TBIrelated data are collected from patient interview and case note review. The outcome data presented here were collected at the patients 6-month follow-up visit. To summarize, the following data were collected: (1) demographic data (age, gender, marital status, preinjury employment status, level of education, type of occupation, history of alcohol and substance abuse, past psychiatric history, family psychiatric history, prior head injuries) and (2) head injury data (mechanism of injury, severity indices such as the GCS recorded at the emergency department [ED] for better consistency, 30 LOC, PTA, 31 results of brain computed tomography scans ordered at the initial ED assessment). We also used the Abbreviated Injury Score 32 (AIS) to quantify other non-tbi injuries that patients may have sustained, and we recorded the details of psychotropic and analgesic medication use at 6 months after TBI. Outcome Measures Psychologic distress. The 28-item General Health Questionnaire 33 (GHQ) is a self-report questionnaire that contains 4 subscales of 7 questions each pertaining to somatic complaints, anxiety, social dysfunction, and depression. A choice of 4 responses is allowed for each question. These were scored in a binomial fashion ( ). Global and psychosocial functioning. The Glasgow Outcome Scale 34 (GOS) is a clinician-rated, 5-point scale of global adjustment to activities of daily living, and of general outcome, widely used for patients with TBI. A score of 5 indicates a return to premorbid level of functioning, whereas lower scores denote a poor global outcome. The Rivermead Head Injury Follow-Up Questionnaire 35 (RHFUQ) is a 4-point self-report scale that assesses 10 aspects of a patient s functioning after TBI, with a total score ranging from 0 to 48. Because it provides a more detailed description of psychosocial functioning than the GOS, it was used as a supplement. High scores on the RHFUQ are indicative of poor recovery. Return to work. Patients were asked if they had resumed employment. Those who had not returned to work because of injuries other than their TBI (n 50) were excluded from this part of the analysis. Statistical Analysis Statistical analyses were conducted by using the SPSS, version a Comparisons were undertaken between dizzy and nondizzy groups using t tests for continuous demographic, injury, and psychosocial variables and chi-square analyses for categoric variables. A 1% level of significance was chosen to adjust for multiple comparisons. For effect size calculations (d for continuous variables; h for dichotomous variables) of the 6-month outcome measures, arcsine transformations were used based on the methodology prescribed by Cohen. 36 Given that return to work is an important marker of outcome and can be easily recorded, we wanted to investigate the extent to which dizziness, combined with other TBI-related variables, would predict resumption of employment at 6 months postinjury. To this end, we undertook a logistic regression analysis with return to work being the dependent variable. Logistic regression is a statistical modeling technique for dealing with a binary or dichotomous outcome measures and can incorporate several binary or continuous predictor variables. The potential predictors incorporated in the logistic regression were chosen based on previous findings in the literature and included demographic (level of education, occupation type) and premorbid health factors (prior head injury, past psychiatric history, alcohol/substance abuse problems), injury severity indices (GCS score, AIS), psychotropic and/or analgesic medication use, and psychologic distress (total GHQ). The Spearman rank correlation was used to evaluate collinearity among the independent variables chosen as potential predictors for return to work. The Hosmer and Lemeshow chi-square 37 was used to assess the goodness-of-fit of the model. Lack of significant intercorrelations among these putative independent variables enabled us to enter them all in the same regression analysis. We ran 2 logistic regression models the first one did not include dizziness ( 2 log L ) whereas the second did ( 2 log L ) allowing us to test the independent effect of dizziness of enhancing predictability for return to work. Ethics The Research Ethics Committee at Sunnybrook and Women s College Health Sciences Centre approved this project, and written consent was obtained from all the study participants. RESULTS Demographic Variables The mean age standard deviation (SD) of the 207 patients was years and 63.8% were men. There were no demographic differences between subjects with and without dizziness (table 1). Injury-Related Information No differences were found between dizzy and nondizzy patients on TBI severity indices. However, dizzy subjects were significantly less likely to have nonhead injuries and more likely to receive psychotropic and/or analgesic medications (table 2).

3 1664 DIZZINESS AND MILD TO MODERATE HEAD INJURY, Chamelian Table 2: Injury-Related Characteristics in Dizzy Versus Nondizzy Patients Characteristics Dizzy (n 138) Nondizzy (n 69) Mechanism of injury (MVC-related) 63.0% 68.1% LOC Altered level of consciousness 50.0% 41.5% Yes, 20min 36.5% 49.2% Yes, 20min 13.5% 9.2% PTA None 1.0%* 2.3% 24h 64.4%* 69.8% 24h 34.7%* 27.9% Mean GCS score SD at the ED t CT scan abnormalities 36.6% 50.0% AIS score SD t No. of psychotropics and/or analgesics mo post-tbi None 40.1% 70.8% % 20.0% % 7.7% % 1.5% Time between accident and 6-mo follow-up visit SD (d) t Abbreviations: CT, computed tomography; MVC, motor vehicle crash. *n 101. n 43. n 123. n 62. t / 2 Tests P Global and Psychosocial Outcomes Although both groups had similar scores on the GOS, dizzy patients had significantly higher scores on all 4 of the GHQ subscales and worse results on the Rivermead Index of psychosocial functioning. They were also significantly less likely to return to work at 6 months after injury. With the exception of GOS score, all the other 6-month psychosocial outcome measures had medium to large effect sizes (table 3). After the logistic regression analyses that were used to predict reemployment at 6 months postinjury, dizziness significantly improved the predictability of the model because the difference between the 2 log likelihoods was significant (P.004). 37 The full regression model resulted in 3 significant independent predictors of return to work, which were dizziness (P.006), total GHQ (P.001), and psychotropic and/or analgesic medication use (P.05). DISCUSSION After mild to moderate TBI, 66.7% of our patients had subjective complaints of dizziness. This group, when compared with the nondizzy controls, was significantly more anxious and depressed, had greater psychosocial dysfunction, and was less likely to return to work. Medium to mostly large effect sizes for these outcome measures substantiate the deleterious effect of dizziness on recovery 6 months post-tbi. There were no group differences in terms of demographic and head injury severity variables that are generally acknowledged to independently predict recovery from mild TBI, 5,6,26,38-40 although the dizzy Table 3: Psychosocial Outcome 6 Months Post-TBI in Dizzy Versus Nondizzy Patients Outcome Measures Dizzy (n 138) Nondizzy (n 69) t / 2 Tests P Effect Size Mean GOS score SD t d.14 Mean RHFUQ score SD t d.80 Mean GHQ score SD Somatic t d.91 Anxiety t d.72 Social dysfunction t d.74 Depression t d.68 Total t d.91 Return to work h.84 No 66.0%* 25.5% Yes 34.0%* 74.5% *n 106. n 51. Small effect size: 0.2. Medium effect size: 0.5. Large effect size: 0.8.

4 DIZZINESS AND MILD TO MODERATE HEAD INJURY, Chamelian 1665 subjects were less likely to have sustained other injuries sparing the brain. To our knowledge, our study is the first to show the predictive value of dizziness on reemployment after a mild or moderate head injury. Failure to regain working activities after TBI has devastating consequences, with loss of financial independence, difficulties in psychosocial adjustment, and deterioration in quality of life. In addition, the societal cost is considerable given that the most common victims of TBI are generally young and employed. 40 Despite the strong association between posttraumatic dizziness and poor psychosocial outcomes, our methodology did not allow us to tease out the causal relationship between these 2 factors. Thus, we cannot say whether the dizziness promoted anxiety and depression or whether the converse was true, that is, psychologic distress leading to an amplification of complaints of dizziness. This point is further emphasized by the subjective manner in which we measured the presence or absence of dizziness. In this regard, studies that have attempted to document vestibular abnormalities after mild to moderate TBI yielded inconsistent findings, ranging from 32% to 65%. 24,41,42 The large number of dizzy patients who do not have objective findings of neural damage reinforces the connection with psychologic factors. Here our data are in accord with studies confirming the association in patients without TBI The neural circuitry involved in generating both anxiety and vestibular symptoms has been recently described. 48 Preliminary evidence from a case study 49 and a case series 50 of vestibular rehabilitation techniques alleviating both posttraumatic dizziness and psychologic distress gives additional support to this model. Although postconcussive dizziness was closely linked to psychologic distress, it also emerged as an independent predictor of outcome. Even after adjusting for confounders such as psychotropic and/or analgesic medication use, dizziness emerged as an independent predictor of return to work 6 months postinjury. This suggests that not all the adverse effects of posttraumatic dizziness on outcome are psychologically mediated. Furman and Jacob 51 have proposed a classification that identifies several interactions between dizziness and psychiatric disorders in which the presence of a psychiatric or psychologic condition does not preclude the possibility of a vestibular or neural etiology as cause of dizziness. The latter may be of peripheral or central 23,41,54 origin. Although dizziness is conceptualized as being mainly a somatic complaint in the postconcussive syndrome, a multidisciplinary approach that also includes psychiatric assessment in treating this condition will be superior to an exclusively medical one. One pitfall of studying patients with mild TBI is the relative nonspecificity of their symptoms. However, a recent study 27 identified 5 subjective complaints that were integral to the postconcussive syndrome, of which dizziness was one. The only study 24 that examined the specific effect of posttraumatic dizziness had many methodologic problems, such as absence of a control group of nondizzy subjects and failure to investigate concomitant psychologic conditions. Their rate of failure to return to work was lower (46%) 24 than that found in our study (66%). However, these 2 rates are not directly comparable because they differ in terms of their postinjury assessment period. In the former study, 24 reemployment was evaluated at 5 years after head injury whereas our patients were assessed only at 6 months post-tbi. CONCLUSIONS Our study is the first to investigate the effect of posttraumatic dizziness on psychosocial outcome in mild to moderate TBI patients. Given that dizziness is among the more specific postconcussive symptoms, this question is of clinical relevance. 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