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Basal Ganglia and Involuntary Movements
Mink reviews the evidence that the basal ganglia are organized to facilitate voluntary movements and inhibit competing movements that might interfere with desired movements. He points out that dysfunctions of these circuits could lead to movement disorders characterized by impaired voluntary movements, the presence of involuntary movements, or both. He proposes a new model, building on existing models and data to encompass a hypothesis of the fundamental pathophysiologic mechanisms underlying chorea, dystonias, and tics.
Computer-Linked Motor Movements
Warwick and colleagues provide exciting insight into the application of cybernetic implant technology to establish a bidirectional link between the human nervous system and a computer for coordinated motor movements. They describe a subject in whom a device is implanted, allowing bidirectional, computer-assisted motor movements that control the subject's hand and allow the subject to further control an electric wheelchair. As described, the use of implant technology to directly measure neurologic signals and stimulate nerve fibers offers an opportunity for the treatment of neurologic and physical impairment. Clearly, this technology is in the early phases of development but offers great potential for neurologic rehabilitation in the future.
Hazard ratios for stroke associated with hormone therapy (HT) based on the presence of hypertension. The hazard ratios for hypertensive nurses were significantly increased in current HT users (A) and in current users of combined estrogen-progestin (B), compared with hypertensive never users of HT.
Estrogen Therapy and Increased Risk of Stroke
Løkkegaard and colleagues studied the potential risk for stroke in women treated with hormone therapy (HT). The study included 13 122 postmenopausal women. In a subset of patients, they found that the presence of hypertension correlated consistently in a significant manner with an increased risk of stroke. Normotensive women had no increased risk of stroke with HT. This study points out that HT should be avoided in hypertensive women. Editorial perspective is provided by Douglas A. Dulli, MD, MS.
Prevalence of Mild Cognitive Impairment
As part of the Cardiovascular Health Study, Lopez and colleagues have determined the presence of mild cognitive impairment (MCI) for the whole cohort and specific subtypes of MCI in detail. Mild cognitive impairment was subclassified as amnestic or multiple cognitive deficits. Of note, 22% of the subjects who were 75 years or older had MCI. Mild cognitive impairment was determined to be a heterogeneous syndrome, with the amnestic form of MCI occuring less frequently than the multiple cognitive deficits type. This carefully designed and performed study provides convincing data on the prevalence of MCI in individuals older than 75 years and further provides new and significant information on the heterogeneous and clinically multifaceted types of MCI.
Risk Factors for Mild Cognitive Impairment
In an accompanying article, Lopez and colleagues again examine the Cardiovascular Health Study database. They find that mild cognitive impairment (MCI) in African Americans was associated with an increased prevalence, low education, low modified Mini-Mental State Examination (3MSE) and digit symbol substitution test (DSST) scores, cortical atrophy, magnetic resonance imaging (MRI)–identified infarcts, and depression. Further, the amnestic type of MCI was associated with MRI-identified infarcts, the presence of apolipoprotein E 4 allele, and low 3MSE scores. The multiple cognitive deficits type of MCI was associated with impaired 3MSE and DSST scores. These 2 articles provide comprehensive and detailed analyses of current knowledge about the prevalence, risk, and subtypes of MCI. The clinical variations and epidemiologic issues of MCI are of great interest, and their study provides definitive answers concerning this emerging clinical syndrome.
Orthostatic Hypotension in Parkinson Disease
It is currently accepted that orthostatic hypotension (OH) is a clinical marker for the diagnosis of multiple system atrophy, but conflicting data indicate that it may also be present in Parkinson disease (PD). Bonuccelli and colleagues have evaluated the presence of autonomic cardiovascular impairment and OH in PD patients. Importantly, they find that there is a high prevalence of sympathetic and parasympathetic failure in de novo PD patients and, when using a drop of at least 20 mm Hg in systolic arterial blood pressure, manometric OH is present in 14% of de novo PD patients. These findings establish the point that autonomic insufficiency is an important issue in PD and should be evaluated regularly in the longitudinal assessment of patients.
Human Immunodeficiency Virus RNA Levels and CD4 Cell Counts Predict Cognitive Impairment
Marcotte et al have studied plasma and cerebrospinal fluid human immunodeficiency virus (HIV) RNA levels in 74 subjects with estimable seroconversion data and normal cognitive function at baseline for subsequent cognitive performance. Neurocognitive outcomes in HIV are strongly influenced by very early systemic virologic and immunologic events. They find that patients with high plasma HIV RNA levels and low CD4 cell counts early after infection were those who most rapidly progressed to significant impairment in cognitive function. Thus, this subgroup of patients should be aggressively treated not only to prevent further immunologic decline but also to prevent more significant cognitive deterioration.
Benign Calf Amyotrophy
Felice et al demonstrate that benign calf amyotrophy is a variant of the benign focal amyotrophy disorders. The cause of the syndrome is unknown. Clinical studies to exclude other causes of calf amyotrophy and careful follow-up examinations to document disease stabilization are necessary to diagnose this uncommon and emerging clinical syndrome.
Clinical Presentation of Facioscapulohumeral Dystrophy
Krasnianski and colleagues describe patients with facioscapulohumeral dystrophy (FSHD) associated with a deletion of chromosome 4q35. They find that the clinical signs and symptoms in patients with the FSHD-associated short fragment on chromosome 4q35 are not restricted to the classical FSHD form of Landouzy and Dejerine, but comprise a variety of clinical manifestations. Of interest is that there seems to be no clear correlation between the atypical subtype and the DNA fragment size due to the deletion. These observations provide a new perspective of phenotype-genotype correlations in the FSHD spectrum.
Voxel-Based Morphometry in Multiple System Atrophy
The morphologic alterations in the cerebellar type of multiple system atrophy (MSA-C) were studied in vivo using voxel-based morphometric analysis of magnetic resonance images (MRIs). Specht and colleagues find that voxel-based morphometric analysis showed a significant loss of cerebellar and brainstem tissue in MSA-C. Their findings provide a precise anatomical location and a distinction between gray and white matter density. Their data provide careful delineation by MRI of the cerebellar lesions in MSA-C and extend previous observations in this area. Further, their data point to the particular involvement of the pyramidal track.
Thalamic Infarcts and Cognition
Annoni and colleagues have studied patients with thalamic infarcts for subsequent cognitive impairments. Six of 9 patients showed some degree of cognitive loss. Specific thalamic nuclei with specific neuropsychologic deficits are correlated. It is of interest that alteration of executive functions usually ascribed to neocortical areas are present in patients with thalamic infarcts. Their study provides new and clinically useful correlations to appreciate the nuances of the spectrum of cognitive impairment with specific thalamic lesions.
This Month in The Archives of Neurology. Arch Neurol. 2003;60(10):1360–1361. doi:10.1001/archneur.60.10.1360
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