French horn embouchure dystonia.
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Adult↗
Biomedical subjects
B Ford
Publications and source records attributed to B Ford.
DNA strand biases and the mutational resilience of genes.
This paper quantifies the resilience of a gene to each class of base substitution. The resilience of a gene is defined as the set of probabilities of synonymous base substitution (one for each type of base substitution on each DNA strand), and is derived from the fraction of all possible substitutions which result in no change of encoded amino acids. We discuss the resilience of the common mutational target genes, lacI and hypoxanthine-guanine phosphoribosyltransferase (hprt), and the p53 tumour suppressor gene. There are inherent strand biases to mutation in terms of the resilience differences between the non-template and template DNA strands. The ability to quantify resilience differences between the two DNA strands contributes to our understanding of strand bias to mutation.
Bacterial Proteins↗
Is essential tremor symmetric? Observational data from a community-based study of essential tremor.
BACKGROUND: Essential tremor (ET) has been variably portrayed in the literature both as a symmetric arm tremor and as an asymmetric arm tremor. Few quantitative clinical or neurophysiological data specifically address the issue of tremor asymmetry in ET. OBJECTIVES: To examine a community-dwelling cohort of subjects with ET to (1) estimate the prevalence of tremor asymmetry and (2) quantify the magnitude of tremor asymmetry. METHODS: Fifty-four subjects with ET, identified in a community-based study of ET in New York City, underwent a Tremor Interview and a videotaped Tremor Examination. The examination included 6 tasks: sustained arm extension, pouring water, drinking water, using a spoon, finger-to-nose movements, and drawing spirals with each arm. Two neurologists rated the severity of tremor using a 0 to 3 clinical rating scale and a total tremor score was calculated (range, 0-36). Fourteen (25%) of 54 subjects also underwent quantitative computerized tremor analysis. RESULTS: The prevalence of asymmetry depended on the definition of asymmetry; small to moderate differences between sides were common. The mean side-to-side difference in clinical ratings for each of the 6 tasks was 0.54 of 3 points, which represented a 1.32-fold difference between sides. Clinical rating scores were higher in the nondominant arm in 39 subjects (72%), higher in the dominant arm in 9 (17%), and equal in 6 (11%). The 2 left-handed subjects had higher clinical ratings on the right. During quantitative computerized tremor analysis, there was a 1.71-fold mean difference between tremor amplitudes in the dominant and nondominant sides, and in 12 subjects (86%), the maximum tremor amplitude was in the nondominant arm. CONCLUSIONS: Small to moderate differences between sides were common in ET. In most community-dwelling subjects, tremor amplitude was greatest in the nondominant arm. In contrast, clinic-based studies have reported greater tremor in the dominant arm; those with ET who seek medical attention are more likely to exhibit severe tremor in their dominant arms. This study documents that mild asymmetry is a fundamental property of ET and that tremor is more severe in the nondominant arm.
Aged↗
How normal is 'normal'? Mild tremor in a multiethnic cohort of normal subjects.
BACKGROUND: While many "normal" subjects exhibit mild clinically detectable tremor, the extent to which this tremor is present has received little attention. OBJECTIVE: To characterize the prevalence and clinical characteristics of mild, clinically detectable tremor in a multiethnic cohort of normal subjects. METHODS: Normal control subjects (n=36) and their relatives (n=67) were enrolled in a community-based case-control study of the familial aggregation of essential tremor. Subjects underwent a tremor interview and videotaped tremor examination. Two neurologists independently rated the severity of tremor during different postures and tasks, and a total tremor score (maximum score, 36) was calculated for each subject. Eight subjects were randomly selected to undergo quantitative computerized tremor analysis. RESULTS: In 103 normal subjects (36 control subjects and 67 relatives of control subjects) the mean total tremor score was 4.8 (range, 0-12.5). Ninety-nine (96%) of 103 subjects had tremor, as defined by a total tremor score of 0.5 or higher. For most tasks, the mean tremor score was greater in the nondominant than in the dominant arm. The total tremor score correlated highly with age (r=0.28; P=.004). There were no sex or ethnic differences in the mean total tremor scores. On tremor analysis, the amplitude and frequency of the tremor differed from that in a group of similarly studied subjects with essential tremor. CONCLUSIONS: Normal subjects almost uniformly have a clinically detectable tremor that is mild and age dependent. Characterization of this tremor helps to establish standards for normal tremor. These standards are crucial for accurate diagnostic classification in population-based studies of essential tremor.
Adolescent↗
Diagnostic criteria for essential tremor: a population perspective.
BACKGROUND: Prevalence estimates vary 2750-fold among the 20 studies of essential tremor (ET). It is not clear how the choice of diagnostic criteria affects research results. OBJECTIVE: To determine the impact of alternative sets of diagnostic criteria on the diagnosis of ET. METHODS: As part of the Washington Heights-Inwood Genetic Study of ET (WHIGET), a population-based study of ET, 285 subjects who include 36 case subjects with probable or definite ET, 34 case subjects with possible ET, and 215 normal subjects were interviewed and examined. All diagnoses in WHIGET were assigned by 2 neurologists. Ten of the 20 published prevalence studies of ET provided diagnostic criteria for ET. Criteria differed in terms of requirements for the distribution, duration, and severity of tremor. These 10 sets of criteria were then each separately applied to the subjects in the WHIGET cohort to determine their impact on the diagnosis of ET. RESULTS: Depending on which diagnostic criteria were applied to the WHIGET cohort, the proportion of WHIGET case subjects with definite or probable ET who would have been diagnosed as having ET was as low as 14% and the proportion of WHIGET normal subjects who would have been diagnosed as having ET was as high as 51%. Diagnostic criteria that included a positive family history of ET or a lengthy duration of tremor would have classified many WHIGET case subjects with ET as normal, whereas criteria that did not specify a minimal tremor severity would have classified many WHIGET normal subjects as having ET. CONCLUSIONS: Alternative sets of diagnostic criteria for ET greatly impact on the diagnosis of ET. For population-based studies, information on tremor type and severity rather than family history should be included in diagnostic criteria.
Adolescent↗
Reliability between two observers using a protocol for diagnosing essential tremor.
Protocols with demonstrated reliability have been established for the diagnosis of numerous movement disorders. whereas in the essential tremor (ET) literature, there is no discussion about the reliability of diagnostic protocols. Lack of knowledge of the reliability of diagnostic protocols in ET limits the use of these protocols because reliability is an essential requirement for scientific quality in data management. The objective of this study was to determine the reliability of a protocol for diagnosing ET. The protocol consists of a Tremor Interview, a videotaped Tremor Examination, and a diagnostic algorithm. Eighty-three subjects with ET, identified in a community-based health study in Washington Heights-Inwood, New York, were matched with 83 control subjects from the same community. These subjects and their relatives are being recruited to participate in the Washington Heights-Inwood Genetic Study of ET. Two hundred twenty-six subjects have been evaluated to date (35 ET cases, 40 controls, 151 relatives). All 226 underwent an 84-item Tremor Interview and 26-item videotaped Tremor Examination. Diagnoses (normal, possible ET, probable ET, definite ET) were independently assigned by two blinded neurologists specializing in movement disorders. The kappa statistic, k, was used to determine diagnostic agreement between these two neurologists. The concordance rate between two raters using diagnostic categories definite ET, probable ET. possible ET, and normal was 80%; kw = 0.84 (near perfect to perfect agreement). The concordance rate between two raters using two diagnostic categories (definite ET and normal) was 100%; k = 1.00 (perfect agreement). There was high correlation between the two raters' total tremor scores (r = 0.89, p < 0.00001). This diagnostic protocol is highly reliable. Research in ET would greatly benefit from diagnostic protocols with demonstrated reliability.
Adolescent↗
Intrathecal baclofen in the treatment of dystonic storm.
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Acute Disease↗
Clinical characteristics of essential tremor: data from a community-based study.
BACKGROUND: 99.5% of individuals with essential tremor (ET) who live in the community have mild tremor and do not attend clinics. Clinic-based studies of ET have not allowed investigators to characterize the full clinical spectrum of this disorder. In community-based studies of ET, the primary focus has been the prevalence rather than the clinical characteristics of ET. OBJECTIVE: To describe the clinical characteristics of ET as seen in a community-based study. METHODS: 73 subjects with ET, identified in a community-based study of ET in Washington Heights-Inwood, New York, underwent a standardized 84-item physician-administered tremor interview and a 26-item videotaped tremor examination which included 12 bedside tests for ET. Two neurologists who specialized in movement disorders and who demonstrated excellent interrater agreement rated the severity of tremor using a 0 to +3 clinical rating scale and assigned a total tremor score (range, 0-36) and a diagnosis of ET. RESULTS: Diagnoses in the 73 cases were: definite ET (18, 24.7%), probable ET (32, 43.8%), and possible ET (23, 31.5%). The mean total tremor score was 17.8 of 36. Thirty-six of 73 (49.3%) were asymptomatic, answering "no" to the question "do you often have shaking or tremor that you can't control?" Sixty-seven of 73 (91.8%) had not been prescribed medication for tremor. On average, subjects received tremor ratings of > or =+2 on only 5.4 of the 12 bedside tests for ET. Kinetic tremor was rated as more severe than postural tremor in 72 (98.6%) of 73 cases. CONCLUSIONS: We present the clinical findings of a group of largely untreated, unselected cases of ET that would not otherwise have come to neurologic attention. The tremor was mild, often asymptomatic, and not uniformly present throughout the examination. It was rarely treated. The kinetic component of the tremor was more severe than the postural component. These clinical data further our understanding of the clinical spectrum of ET.
Adolescent↗
Outcome of selective ramisectomy for botulinum toxin resistant torticollis.
OBJECTIVE: To investigate the long term outcome of selective ramisectomy denervation in patients with botulinum toxin resistant spasmodic torticollis. BACKGROUND: The published surgical series of ramisectomy treatment for torticollis do not provide systematic information on patients who develop resistance to the current standard of treatment-botulium toxin injections. Moreover, there is little information on surgical outcome using rating scale measurements of torticollis, or assessments of functional and occupational capacity. METHODS: Using a structured interview format and videotape assessments of severity of dystonia in a retrospective fashion, detailed follow up information was obtained on 16 patients who underwent open label selective denervation for severe, disabling torticollis, refractory to injections of botulinum toxin. RESULTS: Of 16 patients with disabling torticollis followed up postoperatively for a mean of 5 years, six (37.5%) had a moderate or complete return of normal neck function, as determined using functional capacity scales, whereas 10 had only minimal relief of dystonia or gain in function. Six of the 16 patients (37.5%) underwent a second peripheral denervation operation, and one required a third. Of 11 patients working outside the home before surgery, nine were disabled by dystonia, and only one continued to work after surgery. Dystonia rating scale scores of videotaped examinations using a modification of the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) improved in 12 of 14 patients (85.7%) who underwent selective ramisectomy. When patients with primary botulinum toxin resistance were excluded, the magnitude of benefit for this subgroup was 31.9% of the baseline dystonia score (p<0.0002), comparable with the degree of improvement in a group of control patients receiving botulinum toxin treatment for torticollis. CONCLUSION: About one third of patients with torticollis resistant to injections of botulinum toxin may derive modest long term functional improvement from selective denervation, with a reduction in dystonia by about 30%, but remain unable to work.
Adult↗
Does a screening questionnaire for essential tremor agree with the physician's examination?
In research studies of essential tremor (ET), monetary and geographic factors often necessitate diagnosis by interview rather than by examination. Few attempts have been made to determine the validity of a screening instrument for ET. A total of 242 subjects (33 definite or probable ET, 54 possible ET, and 155 normal) were part of a community-based family study of ET in northern Manhattan. Subjects underwent a tremor interview and videotaped tremor examination. The interview included 12 screening questions for ET. Two neurologists rated the severity of tremor on videotape and assigned diagnoses. The subjects' responses to the 12 screening questions were compared with the neurologic examination and the neurologists' diagnoses. There was an association between the number of affirmative responses on the 12-item screen and the severity of tremor during the videotaped tremor examination (r = 0.66, p < 0.01). Including those with probable and definite ET and defining a positive screen result as an affirmative response to at least 1 of 12 screening questions, the sensitivity of the screening questionnaire was 73%, the specificity was 96%, and the positive predictive value was 80%. The responses to the questionnaire closely correlated with the severity of tremor on neurologic examination. The questionnaire had moderate validity for subjects with probable or definite ET; subjects with mild ET often screened negative. Hence, in population-based studies and family studies of ET, it is important to examine all subjects for the presence of mild asymptomatic ET.
Adolescent↗
Post-traumatic shoulder 'dystonia': persistent abnormal postures of the shoulder after minor trauma.
The authors describe two patients with fixed shoulder elevation and prominent regional muscle hypertrophy that developed within days after local minor injury. The condition lacked several typical features of dystonia, such as the presence of torsional movements, task specificity, or relief by antagonistic gestures. These patient reports add to the growing literature indicating that persistent post-traumatic abnormal postures and muscle hypertrophy in different body parts may be a distinct response of the nervous system to injury.
Accidents, Traffic↗
Intrathecal baclofen in the treatment of dystonia.
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Baclofen↗
Prevalence of asymptomatic tremor in relatives of patients with essential tremor.
BACKGROUND: The extent to which essential tremor (ET) clusters within families (ie, the familial aggregation of ET) is not precisely known. In part, this is because studies assign disease status in relatives of patients with ET based solely on interviews without conducting physical examinations. This may lead to underascertainment of affected relatives with mild asymptomatic ET. OBJECTIVE: To determine the prevalence of asymptomatic ET among relatives of patients with ET. METHODS: Interview and examination of 25 patients with ET and 58 of their relatives. The interview included 12 questions that screened the patients for ET. Two neurologists who specialize in movement disorders reviewed the videotaped examinations. Based on standardized criteria, diagnoses included ET (definite, probable, or possible) on normal. RESULTS: Of the 8 relatives who received diagnoses of ET, 5 (62.5%) had asymptomatic ET. Hence, 5 (8.6%) of the 58 relatives (95% confidence interval 1.4%-15.8%) had asymptomatic ET. In those with asymptomatic ET, there was a preponderance of young individuals with mild tremor in the nondominant hand. CONCLUSIONS: The prevalence of asymptomatic ET in relatives of patients with ET was similar to that of symptomatic ET. Family studies that do not perform both an interview and a physical examination will underascertain the number of affected relatives. Therefore, future family studies should evaluate relatives of patients with ET with an interview supplemented by a physical examination.
Aged↗
Idiopathic torsion dystonia linked to chromosome 8 in two Mennonite families.
The DYT1 locus on chromosome 9q34 is responsible for most childhood limb-onset idiopathic torsion dystonia (ITD). Linkage to DYT1 has been excluded in families with adult-onset, and predominantly cranial-cervical, ITD. We mapped a locus (DYT6) associated with prominent cranial-cervical ITD in two large Mennonite families to chromosome 8. An identical haplotype spanning 40-cM segregates with ITD in these families, suggesting a shared mutation from the recent past.
Adolescent↗
Spinal myoclonus induced by an intrathecal catheter.
We report a case of spinal myoclonus induced by the tip of an intrathecal catheter in a 35-year-old patient with severe, adult-onset, generalized dystonia of unknown cause, treated for 2 years using intrathecal baclofen. One month after a falling episode, the patient developed focal myoclonus of the right proximal leg whenever she stood up from a seated position. The electrophysiologic recordings were compatible with spinal segmental myoclonus, originating at a focus corresponding to the L2-S2 segments. At this site, the tip of the intrathecal catheter was demonstrated by myelography to be in close proximity to the nerve roots and conus medullaris. The myoclonus resolved promptly once the catheter tip was withdrawn. We review the literature on spinal myoclonus and discuss the possible mechanisms of spinal myoclonus pertaining to the present case. This report represents an unusual complication of intrathecal catheter systems that, if recognized, can lead to prompt therapeutic intervention.
Adult↗
Progressive cognitive decline with truncal/limb ataxia and ballistic movements.
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Aged↗
The Washington Heights-Inwood Genetic Study of Essential Tremor: methodologic issues in essential-tremor research.
Essential tremor (ET) is the most prevalent movement disorder. It is unknown to what extent ET clusters within families, and the role of genetic susceptibility in etiology of ET has not been adequately investigated at the population level. The problem is largely methodological, with few well-designed studies. The Washington Height-Inwood Genetic Study of ET, begun in 1955, is designed to investigate the genetics of ET using a methodology that has not been applied to ET research to date. Part of the design includes a new set of clinical and electrophysiological diagnostic criteria for ET; the present paper describes this novel study design.
Case-Control Studies↗
Chemoprevention of cancer: review of the literature.
PURPOSE/OBJECTIVES: To explain the concept of cancer chemoprevention, describe chemoprevention trials, and discuss the agents currently under study to lower the incidence of oral premalignancy and head and neck, lung, breast, prostate, and colon cancers. DATA SOURCES: Published journal articles, books, bulletins, monographs, protocols, and professional experience. DATA SYNTHESIS: Chemoprevention is a promising approach to cancer control, and several key agents have been identified that may be able to block carcinogenesis. Phase III chemoprevention trials are being conducted to identify the role of agents (e.g., retinoids, tamoxifen, finasteride, aspirin) in cancer prevention. CONCLUSION: Knowledge of the genetic and hormonal changes that occur during carcinogenesis continues to increase. Agents are being identified that block the development of cancer by arresting carcinogenesis. As more agents are identified and investigated, their importance in chemoprevention is increasing. IMPLICATION FOR NURSING PRACTICE: The goal of nursing care for participants in prevention trials is to promote compliance with the study protocol while supporting optimum quality of life. Through proactive education of participants, family members, and the public and skillful management of side effects, nurses can play an integral part in the success of prevention trials.
Adult↗