Essential tremor: predictors of disease progression in a clinical cohort.

OBJECTIVES: To examine the utility of baseline factors to predict disease progression among a clinical cohort of patients diagnosed with essential tremor. MEASURES: Tremor Rating Scale (TRS). METHODS: A clinical series of 128 consecutive patients diagnosed with essential tremor was included for study. 45 (35%) patients had at least one follow-up exam (mean = 3.6 years). Baseline predictive factors examined included age, age at onset of symptoms, disease duration, sex, handedness, total tremor rating score, asymmetric tremor ratings, location of initial tremor onset, use of drugs for movement disorders, ETOH responsiveness of tremor, association of head or neck tremor, history of depression, familial history of essential tremor, Parkinson's disease, Alzheimer's disease and other movement disorders. RESULTS: On average, the TRS total score increased by <1 point per year before the first visit to the clinic and by about 2 points per year during the observed study period. The increase of 2 points per year during the observed study period represented an approximate 12% annual change from the mean TRS total score at the first clinic visit. Significant (p<0.05) predictive factors associated with increased tremor severity at the initial clinic visit included older age, longer disease duration, use of movement disorder drugs and the presence of voice tremor (r = 0.24, 0.27, 0.25, 0.19). The major factors associated with an increase in tremor severity from the initial clinic visit to the last follow up included asymmetrical tremor ratings, unilateral initial tremor onset and longer follow-up duration (r = 0.32, 0.31, 0.30). Multivariate regression analysis accounted for about 17-30% of the variance in tremor ratings (p<0.05). CONCLUSION: Essential tremor is a slow, progressive disease. The rate of disease progression and the factors associated with disease progression may vary throughout the disease course.

Activities of daily living among heart transplant candidates: neuropsychological and cardiac function predictors.

BACKGROUND: The ability of patients to perform day-to-day tasks (e.g., medication management, dietary regulation) is an important concern of transplant teams. METHODS: We studied a clinical series of 75 heart transplant candidates and 38 controls to examine the predictive validity of demographic, neuropsychologic, and cardiac function variables to a performance-based measure of instrumental activities of daily living (IADL) capacity (i.e., Everyday Problems Test, EPT). RESULTS: Multiple regression analyses, controlling for education and race, indicated that neuropsychologic tests accounted for between 34% and 67% of the variance across IADL domains (e.g., cooking, household chores, medication management). The IADL capacity was most consistently predicted by long-standing verbal ability (Shipley Institute of Living Scale-Vocabulary, SILS-VOC) and psychomotor speed and mental flexibility (Trail Making Test-Part B, TMT-B). Similarly, SILS-VOC and TMT-B also tended to show the best operating characteristics (i.e., sensitivity, specificity, positive predictive power, negative predictive power) for detection of dependence across IADL domains. In contrast, cardiac function measures (e.g., cardiac output, mean atrial pressure) were largely unrelated to the patient's performance on the paper-and-pencil EPT task. CONCLUSIONS: Long-standing intellectual ability, and a measure of speeded information processing and mental flexibility are the best predictors of IADL capacity.

Thalamic deep brain stimulation for tremor-predominant Parkinson's disease.

OBJECTIVES: Determine the long-term efficacy of thalamic deep brain stimulation (DBS) for treatment of tremor among individuals with tremor-predominant Parkinson's disease (PD).Design. Longitudinal, unblinded assessment of tremor and activities of daily living (ADL) at baseline (pre-surgical), and post-operative intervals of 1, 3, and 12 months, and annually thereafter up to 3 years. METHODS: A clinical series of 19 individuals undergoing placement of a DBS system for treatment of PD-related tremor. A battery of subjective and objective measures of tremor was completed at planned pre- and post-operative intervals. RESULTS: Stimulation was associated with significant improvement on subjective and objective measures of ADL performance, midline tremor, and contralateral upper and lower extremity tremor, including parkinsonian resting and action tremors, over the follow-up period. Ipsilateral tremor showed little or no effect of stimulation after the first 3 months. Antiparkinsonian medication use and stimulation parameters showed little or no change over the course of follow-up. About half (53%) of all individuals reported at least one side effect, generally mild, during the follow-up period, with paresthesias and dysarthria being the most common. A total of two leads required replacement due to (1) infection, and (2) adverse side effects (i.e. burning and tingling with stimulation). CONCLUSION: DBS is associated with stable tremor control in PD. Side-effects are typically easily managed with stimulation adjustments, although in some cases lead replacement may be required.

Thalamic deep brain stimulation for essential tremor: recommendations for long-term outcome analysis.

OBJECTIVES: Determine the efficacy of thalamic deep brain stimulation (DBS) for tremor control among individuals with essential tremor (ET). METHODS: A clinical series of 52 consecutive individuals undergoing placement of a DBS system for treatment of ET completed an unblinded battery of subjective and objective measures at postoperative intervals of one, three, and 12 months, and annually thereafter up to three years. The assessment battery included measures of tremor and activities of daily living. RESULTS: Both subjective and objective measures showed that stimulation was associated with significant improvement at nearly every postoperative interval as compared to pre-operative and stimulation 'off' ratings of activities of daily living functioning, midline tremor, contralateral upper extremity tremor, and contralateral lower extremity tremor. Ipsilateral tremor showed some improvement with stimulation, but only within the first three months. Trend analysis showed stable tremor control. Stimulation settings remained largely unchanged after the first three months. Dysarthria was more common among those with bilateral stimulation. A range of missing data estimation methods were performed, and subsequent analyses corroborated the main findings of the study. CONCLUSION: Thalamic DBS is generally a well-tolerated and effective treatment for ET. Methodological and analytical recommendations are provided for the evaluation of long-term outcome.

Predictors of pain 1 year post-spinal cord injury.

OBJECTIVE: To determine the predictive validity of demographic and medical characteristics to the subsequent development of pain 1 year post-spinal cord injury (SCI). DESIGN: Prospective longitudinal design using data from 18 Model Spinal Cord Injury Systems of Care. PARTICIPANTS: Adults 18 years or older with traumatic-onset SCI (n = 540) evaluated at 1 year postinjury. OUTCOME MEASURES: A single item from the Short Form-12 that assessed pain interference in day-to-day activities using a 5-point Likert scale. PREDICTOR VARIABLES: Demographic and medical characteristics, individual and total medical complications during rehabilitation, and insurance provider. RESULTS: Univariate analyses showed age, education, marital status, primary occupation at the time of injury, American Spinal Injury Association motor score, and sponsor of care to be related to pain interference 1 year post-SCI. Polychotomous logistic regression indicated that age and occupational status at the time of injury were the only significant unique predictors of pain interference. The youngest (aged 18-29 years) and oldest (aged 60 years and older) age groups reported the least amount of pain interference, whereas individuals unemployed at the time of injury were significantly more likely to report pain interference. None of the other predictor variables was significant. CONCLUSION: Age and occupational status appear to be important predictors of pain interference 1 year post-SCI. Future directions of study and limitations are discussed.

Impact of demographic and medical factors on satisfaction with life after spinal cord injury: a normative study.

OBJECTIVE: The aim of this study was (1) to examine demographic and medical predictors of the Satisfaction With Life Scale (SWLS) among individuals with spinal cord injury (SCI) and (2) to provide a normative table for the SWLS that includes appropriate adjustments for the most important predictors of life satisfaction. STUDY DESIGN: We examined predictors of the SWLS including age, education, sex, race, injury duration, number of rehospitalizations, marital status, employment status, SCI etiology, and level of neurological impairment. PARTICIPANTS: Individuals in the National Spinal Cord Injury Statistical Center database [from 18 SCI model systems (1995-1999)] undergoing follow-up assessment were included for study. OUTCOME MEASURE: Satisfaction With Life Scale. RESULTS: Univariate analyses indicated that marital and employment status, race, sex, education, and injury duration were significant factors associated with scores on the SWLS. In general, individuals who were female, white, married, and currently employed and had a higher education and longer injury duration reported significantly higher scores on the SWLS (P < .01). Effect-size estimates for these factors ranged from 0.16 to 0.41. Regression analyses showed that education, employment status, and injury duration were the strongest unique predictors of satisfaction with life but accounted for only 10% of the variance. CONCLUSION: The SWLS is a global measure of life satisfaction and is relatively unrelated to demographic and medical characteristics. Normative tables are provided for epidemiologic comparison.

The utility of K-correction to adjust for a defensive response set on the MMPI.

This study examined the utility of the K-correction procedure to adjust for a defensive response set on the MMPI. The sample consisted of 61 patients with end-stage lung disease undergoing psychosocial evaluation for transplantation. Participants were separated into defensive and non-defensive groups using a median split on the K scale (defensive group T score 59) as the cutoff score. The MMPI was scored once in the standard manner and then rescored omitting all K-scale items from the clinical scales. As hypothesized, raw score analysis after omitting K-scale items showed the defensive group endorsed significantly fewer items on all five scales involving K-correction (Scales Hs, Pd, Pt, Sc, Ma). Analysis of K-corrected T scores on Scales Hs, Pd, Pt, and Sc using standard procedures showed a significant group difference only on Scale Hs with a higher T score found among the defensive group. The defensive and nondefensive groups were not significantly different in demographic, medical, or psychiatric characteristics suggesting that the tendency to respond in a defensive manner is the major characteristic that distinguishes the two groups. Taken together, these results provide support for the use of the K-correction procedure when examining MMPI clinical profiles among patients with end-stage pulmonary disease undergoing evaluation for transplantation.

Self-report measures among transplant candidates: the impact of evaluative situations.

Experiment 1 was a between-subjects design comparing transplant candidates completing self-report measures under an evaluative versus an anonymous research condition. A cardiac disease group and a healthy community group served as controls. Transplant candidates in the anonymous research condition reported significantly more depression, anxiety, and negative affectivity as compared with transplant candidates in the evaluative condition and community controls. In contrast, the evaluative transplant group (a) did not differ from the community controls on any of the self-report measures, and (b) reported significantly less depression than cardiac disease controls. Experiment 2 was a within-subjects design with transplant candidates completing self-report measures under both an evaluative and an anonymous research condition. Significantly greater anxiety was reported under the anonymous research condition. Social desirability was significantly related to change in self-reported anxiety and depression across conditions, but was unrelated to change in endorsement of personality characteristics.

Neuropsychological performance as a function of cardiac status among heart transplant candidates: a replication.

This study examined the relationship between cardiac function and cognitive test performance among candidates for heart transplant. Participants were 26 individuals undergoing heart catheterization within one day of completing a battery of cognitive tests. Partial correlation analyses controlling for age and education were used to examine the relationship between cardiac function and cognitive performance. Results replicate previous findings in that increasing hemodynamic pressure variables, e.g., pulmonary artery systolic pressure, were associated with decreased cognitive performance on a measure of psychomotor speed and attention (Trail Making Test-Part A: r=.53). In contrast, cardiac output and cardiac index appeared to be not significantly related to cognitive performance. Taken together, poor performance on cognitive tests among heart transplant candidates appears to be attentionally mediated.

A defensive response set and the relation between cognitive and emotional functioning: a replication.

This study was designed to examine the hypothesis that a defensive self-report response set tends to attenuate the strength of the relationship between self-reported emotional functioning and cognitive tests, particularly the functioning of verbal memory. 75 patients with end-stage lung disease were administered the MMPI and a cognitive test battery as part of a psychosocial evaluation for transplantation. Patients were separated into defensive and nondefensive groups using the MMPI F - K Gough Dissimulation index (raw score F minus K < or = -15). Cognitive factor scores were generated and correlated with non-K-corrected raw scores of MMPI Scales 2, 7, and 8. Correlation coefficients were compared across groups. As predicted, increases on Scales 2 and 7 were significantly associated with decreased functioning of verbal memory (r = -.35 and -.34, respectively) among the nondefensive group but were unrelated in the defensive group. It is argued that the attenuation of the relationship between self-reported emotional status and verbal memory functioning is, in part, due to a restricted range of symptom endorsement on the MMPI among the defensive group. These findings replicate those previously reported using a sample of patients with cardiac disease.

Parkinson disease: handedness predicts asymmetry.

OBJECTIVE: To determine the proportion of individuals in a clinic-based setting that present with asymmetric Parkinson disease (PD) and identify predictive factors associated with asymmetric symptoms. METHODS: The authors examined right vs left difference scores on the Unified Parkinson Disease Rating Scale motor subscale in a consecutive clinical series of 1,277 individuals diagnosed with PD. Predictors of asymmetry included sex, symptomatic disease duration, age at onset, initial motor symptom laterality, handedness, and medical history variables (e.g., family history of PD). RESULTS: Nearly half the sample (46%) met criteria for asymmetric disease based on a right vs left difference score of > or =5 points, and 12% of the sample had a difference score of > or =10 (difference score: mean = 4, SD = 3.4). All three cardinal features of PD showed characteristics of asymmetric disease presentation. Multiple regression analyses showed that an increased discrepancy between right- and left-sided symptoms was significantly associated with a shorter disease duration, younger age at symptomatic onset, asymmetric initial symptom onset, hand dominance, and a positive self-reported family history of "other" neurodegenerative disorder. Hand dominance was related to the side of asymmetric disease such that left-handed individuals tended to have more severe disease on the left side of the body. CONCLUSION: Asymmetric presentation of Parkinson disease features was a common occurrence in the clinical cohort. Asymmetry was reliably predicted by several clinical characteristics, although the moderate level of explained variance (i.e., between 16 and 23%) highlighted the need for additional research examining predictive models of asymmetric disease. Recommendations for the classification and measurement of asymmetric disease are discussed.

Bilateral thalamic deep brain stimulation: midline tremor control.

OBJECTIVES: To determine the efficacy of bilateral deep brain stimulation (DBS) for management of midline tremor (head, voice, tongue, trunk) in patients with essential tremor. DESIGN: Prospective assessment of tremor at baseline (presurgical), and postoperatively at 1, 3, and 12 months, and annually thereafter. METHODS: A clinical series of 22 individuals undergoing staged, bilateral DBS for treatment of essential tremor. The tremor rating scale was the primary outcome measure. RESULTS: Midline tremor showed significant improvement with stimulation "on" at nearly every postoperative interval when compared with stimulation "off" and with baseline tremor. Bilateral stimulation was associated with a significant incremental improvement in midline tremor control compared with unilateral stimulation: average "stimulation on" percentage change in midline tremor from the unilateral to bilateral period was 81%. Head and voice tremor showed the most consistent improvement. Among those requiring a change in stimulation parameters because of side effects, dysarthria, disequilibrium, motor disturbances, and paraesthesiae were the most common. Dysarthria was more common with bilateral (n = 6; 27%) than with unilateral (n = 0) stimulation. Stimulation parameters remained largely unchanged after the first three months. Nine of 44 leads placed (20%) required subsequent repositioning or replacement. CONCLUSIONS: Unilateral thalamic stimulation significantly improves midline tremor, and subsequent bilateral thalamic stimulation offers an additional incremental improvement in midline tremor control.

Nursing home residence: quality of life among individuals with spinal cord injury.

OBJECTIVE: To examine the quality of life among individuals with spinal cord injury currently living in a nursing home vs. community residence. DESIGN: A case-control design matched nursing home and community residents on numerous demographic and medical characteristics. Two groups of 37 individuals (nursing home vs. community residents) were matched case-for-case on age (i.e., within 10 yr), education, gender, race, marital status, and impairment level. Etiology of spinal cord injury, American Spinal Injury Association Impairment Index at the time of rehabilitation discharge, and injury duration, although not specifically matched, were not significantly different between groups (P > 0.05). Outcome measures included the Satisfaction With Life Scale, and the Craig Handicap Assessment and Reporting Technique (CHART). RESULTS: Results indicated that overall self-reported quality of life was significantly lower among nursing home residents compared with matched community-dwelling residents (mean = 18 and 14, respectively). Similarly, self-reported handicap was significantly higher among the nursing home residents compared with community residents (mean = 337 and 181, respectively), particularly in the areas of physical independence, mobility, occupational functioning, and economic self-sufficiency (P < 0.05). In contrast, the score on the CHART social integration subscale was similar across groups (P > 0.05). CONCLUSION: Despite matching numerous variables, the nursing home residents demonstrated significantly lower quality of life across multiple domains as compared with their community-dwelling counterparts. Additional research is needed to examine the specific mechanisms associated with these differences.

Quality of life after spinal cord injury caused by gunshot.

OBJECTIVE: To determine what effect gunshot-caused spinal cord injury (SCI) has on self-reported quality of life (QOL) and on the frequency of pain sufficient to interfere with day-to-day activities. DESIGN: Follow-up, case-control design. SETTING: Analysis of data obtained from the (US) National Spinal Cord Injury Statistical Center from 18 funded Spinal Cord Injury Model Systems. PARTICIPANTS: Individuals with traumatic onset SCI (n = 1901). From these, 111 persons with gunshot-caused SCI were matched to persons with nongunshot SCI. MAIN OUTCOME MEASURES: Satisfaction with Life Scale (SWLS), the Craig Handicap Assessment and Reporting Technique (CHART), Medical Outcomes Study Short-Form Health Survey (SF-12), and an individual pain item from the SF-12. RESULTS: No between-group differences were found on any of the QOL outcome measures. In contrast, those with SCI caused by gunshot reported that pain more frequently interfered with day-to-day activities than the matched comparison group. CONCLUSIONS: SCI caused by gunshot appears largely unrelated to QOL, after controlling for demographic and medical characteristics associated with this group. Gunshot as a mechanism of SCI may place individuals at an increased risk of subsequent development of pain that interferes with activities of daily living.

Bladder management and quality of life after spinal cord injury.

OBJECTIVE: This study examines the quality of life among individuals with spinal cord injury requiring assistance for bowel and bladder management vs. those with independent control of bowel and bladder. DESIGN: Two groups of 53 individuals each were matched case for case on age, education, sex, race, and lesion level. Outcome measures included the Satisfaction With Life Scale, the Craig Handicap Assessment and Reporting Technique (CHART), and the SF-12. RESULTS: Satisfaction with life was significantly lower among dependent individuals with impaired bowel and bladder functioning as compared with individuals with independent bowel and bladder control. Similarly, dependent individuals reported greater self-reported handicap (CHART) than independent individuals in the areas of physical independence, mobility, and occupational functioning. However, dependent and independent individuals did not differ in the areas of social integration and economic self-sufficiency. Item analysis on the CHART item assessing number of social contacts initiated in the previous month suggested that dependent individuals may have difficulty initiating new social contacts. Independent individuals reported better overall physical health (SF-12) than dependent individuals. Mental health (SF-12), however, did not differ across groups. CONCLUSIONS: Individuals with impaired bowel and bladder control reported lower quality of life on several domains compared with those with independent control of bowel and bladder. Though the two groups did not differ in self-reported social integration, dependent individuals may have greater difficulty creating new social relationships.

Gunshot versus nongunshot spinal cord injury: acute care and rehabilitation outcomes.

OBJECTIVE: To examine the impact of gunshot-caused spinal cord injury on acute and rehabilitative care outcome using a case control design. DESIGN: Two groups (i.e., gunshot- vs. nongunshot-caused spinal cord injury) of 212 individuals were matched case-for-case on age (i.e., within 10 yr), education, gender, race, marital status, primary occupation, impairment level, and Model System region. Outcome measures included length of hospital stay, functional status (FIM), treatment charges, and home discharge rates. RESULTS: The two groups did not differ in the length of stay during acute and rehabilitative care, charges during rehabilitative care, or postrehabilitation discharge placement. Several significant between-group differences in treatment procedures were noted (e.g., prevalence of spinal surgery), which may, in part, account for the higher acute-care charges among those persons with nongunshot-caused spinal cord injury. CONCLUSION: Once an individual is stabilized and admitted for rehabilitative care, gunshot etiology of spinal cord injury seems largely unrelated to the initial rehabilitation outcome.

Test-retest reliability of the Donovan spinal cord injury pain classification scheme.

STUDY DESIGN: Videotape rating by independent viewers. OBJECTIVE: To determine the test-retest reliability of the Donovan spinal cord injury (SCI) pain classification scheme. SETTING: Rehabilitation Centre, Alabama, USA. METHODS: A total of 28 individuals with SCI reported 60 pain sites. A structured interview and physical exam were used to illicit information to classify each pain site according to the Donovan criteria. All structured interviews and exams were videotaped. Three independent raters viewed the videotapes on two occasions, separated by a 3-month interval, and classified each pain site using the Donovan pain classification scheme. RESULTS: Considering all three raters together, 78% of the pain sites were consistently classified from one period to the next. Within each rater, consistent classification ranged from 67 to 83%. However, inter-rater agreement for the classification of each pain site into the various types of pain was low for both periods (about 50-60%). CONCLUSIONS: Pain classification within each rater generally showed adequate test-retest reliability when using the Donovan SCI pain classification scheme. However, reliability estimates of agreement across raters highlight the ongoing need to exam and improve the psychometric characteristics of the various pain classification schemes.

Does memory test performance in children become more consistent with age? Cross-sectional comparisons using the WRAML. Wide Range Assessment of Memory and Learning.

This study examined intertask consistency on the Wide Range Assessment of Memory and Learning (WRAML), using two age cohorts of children. Eighty-one neurologically impaired children and 76 matched (i.e., age, gender, race) controls were separated into two age groups, 5- to 9- and 10- to 14-year-olds. Performance on four subtests from the WRAML Memory Screening Index were examined. For the older neurologic sample, all six intertask correlations were significant (mean r = .58) while only three of the six correlation coefficients were significant among the younger neurologic group (mean r = .26). In contrast, only three of the six intertask coefficients were statistically significant in both the younger and older controls. A possible explanation for these divergent findings and clinical implications of intertask variability on memory measures are discussed.

Developmental memory performance: inter-task consistency and base-rate variability on the WRAML.

Two studies examined developmental memory test consistency and base-rate variability on the Wide Range Assessment of Memory and Learning (WRAML) using three age cohorts from the standardization sample. Study 1 examined inter-subtest correlation coefficients across the nine subtests of the WRAML and compared across three age cohorts (5, 11, 16 to 17 year olds). An age-related increase in inter-task consistency was found (mean r = .26 and .42 for the youngest and oldest age groups, respectively). However, correlation coefficients were generally in the low to moderate range (rs = .2 to .5) for all three cohorts suggesting considerable performance variability across memory subtests. Study 2 examined base-rate variability in the WRAML standardization sample using several different methods. More specifically, base-rate information is provided for the maximum discrepancy between subtests, profile strengths and weakness (i.e., discrepancies from the mean scaled score), and the prevalence of individuals within the "deficient" performance range (i.e., < = 2 SD below normative means). In addition, performance variability across the four WRAML index scores was examined by determining the prevalence rates for the maximum discrepancy (1) between index scores, and (2) from the General Memory Index compared to the other three index scores. Performance discrepancies tended to be higher among the youngest group. Again, however, considerable performance variability was observed across all three age cohorts. Implications for clinical practice are discussed.

Neuropsychological functioning among heart transplant candidates: a case control study.

Neuropsychological performance was examined among a group of patients with end-stage heart disease undergoing routine evaluation for transplantation using a matched case-control design. Heart transplant candidates and controls were matched case by case for gender, race, education and age range. In order to match all 44 controls, a clinical series of 303 heart transplant candidates evaluated between October 1995 through March 1998 were considered. Although not specifically matched on variables of estimated IQ and socioeconomic status, statistical analysis showed no group differences on these variables. A separate analysis of variance on each neuropsychological test indicated that the heart transplant candidates performed significantly worse than controls on tasks of fine motor speed and dexterity (i.e., Grooved Peg Board), psychomotor speed and mental flexibility (i.e., Trail Making Test, Part B), and abstract reasoning and problem solving ability (i.e., Shipley Institute of Living Scale-Abstraction subtest). Implications of the results and future directions are discussed.