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Shapiro provides a basic science review of neuronal mechanisms involved in learning and memory, including issues related to hippocampal neuropsychology, synaptic and cellular electrophysiology, pharmacology, and molecular genetics. Circuits within the hippocampus are remarkably plastic, and this plasticity is mediated in part through changes in synaptic strength and revealed by long-term potentiation (LTP) and depression (LTD). These functions are mediated through NMDA receptors, and impairment of them prevents LTP induction. The concepts of place fields and memory location in time and space are important new ideas that are presented clearly.
Titin and Myasthenia Gravis
Yamamoto and colleagues report that anti-titin antibodies are a sensitive marker of thymoma associated with myasthenia gravis (MG) and justify a careful patient evaluation for thymoma in any MG patient showing these antibodies. Johan A. Aarli, MD, provides an insightful editorial and addresses important clinical issues.
New Findings in Machado-Joseph Disease
Jardim and colleagues correlate unstable DNA (CAG) triplet repeat lengths with specific neurologic signs and symptoms of Machado-Joseph disease (MJD). Nuclear opthalmoplegia is associated with type 1 MJD, whereas supranuclear opthalmoplegia is associated with type 3 MJD. The authors also describe associations of pyramidal findings and dystonia with increased CAG expansions. Once again, understanding the phenotype requires definition of the genotype.
Ventilation in Guillain-Barré Syndrome
Lawn and colleagues provide important guidelines as to when to proceed with intubation and mechanical ventilation for patients experiencing respiratory failure with the Guillain-Barré syndrome. To some extent, mechanical ventilation can be predicted on the basis of clinical information and simple bedside tests. This critical area of patient management is elegantly reviewed in an editorial by Angelika F. Hahn, MD, FRCPC.
Proposed flowchart for the use of clinical and respiratory parameters in the management of Guillain-Barré syndrome. Hughes disability scale score of less than 3 indicates that the patient is able to walk unassisted more than 5 m. Hughes disability scale score of 3 or more indicates that the patient is unable to walk more than 5 m or worse (ie, bedridden or receiving mechanical ventilation). VC indicates vital capacity; PImax, maximal inspiratory pressure (expressed as positive values for simplicity; see "Patients, Materials, and Methods" section in the text); PEmax, maximal expiratory pressure; and ICU, intensive care unit.
Nutt and Nygaard define the short- and long-term responses to levodopa in subjects with dopa-responsive dystonia (DRD). They find that retained dopamine storage in DRD may prolong the short-term response and blur the distinction between the short- and long-term responses. The decline in motor function in DRD upon withdrawal of long-term levodopa use resembles that of Parkinson disease. These features of levodopa therapy provide critical insights into dopamine storage and turnover in this syndrome.
Early Electrodiagnostic Findings in Guillain-Barré Syndrome
Gordon and Wilbourn describe the electrodiagnostic abnormalities in the first week of the Guillain-Barré syndrome (GBS) in an attempt to determine if there are early patterns suggestive of GBS. They define specific and early electrodiagnostic features to aid in early diagnosis and implementation of therapy.
Torsin A and Torsin B in the Brain
Konakova and colleagues describe the central nervous system distribution of torsin A and torsin B and review their potential role in synaptic functioning. These proteins are important for normal neurologic function, and a deletion of a GAG at codon 302 in torsin A results in the loss of 1 glutamic acid, which results in autosomal dominant torsin dystonia.
Hypometabolism in Temporal Lobe Epilepsy
Lamusuo and colleagues demonstrate that fludeoxyglucose F 18 measurements are sensitive for localizing the epileptogenic zone in patients with temporal lobe epilepsy. The temporal hypometabolism, however, was not related to the severity of histologic hippocampal damage. This is an important metabolic, clinical, and neuropathologic correlation study defining the state of altered temporal lobe neurons and the clinical expression of epilepsy.
Spierings and colleagues compare the efficacy, tolerability, and safety of almotriptan and sumatriptan for the treatment of migraine. These 2 agents are similarly effective in the acute treatment of moderate or severe migraine, and both are well tolerated and safe.
Early Onset of Alzheimer Disease due to a Presenilin 1 Gene Mutation
Janssen and colleagues describe 3 affected individuals in a kindred with early-onset autosomal dominant Alzheimer disease due to a presenilin 1 gene missense mutation at codon 153 resulting in a leucine-to-valine change.
Measuring Multiple Sclerosis
Cohen and colleagues, representing a national consortium of investigators, have developed and validated the Multiple Sclerosis Functional Composite (MSFC) to measure clinical outcome in patients with multiple sclerosis. They found that the MSFC had excellent intrarater reliability in a phase 3 clinical trial and that it is a valuable quantitative instrument to measure and evaluate neurologic impairment and disability over time.
Mutations in Wilson Disease
Wu and colleagues characterize the spectrum of mutations in the copper-transporting P-type adenosine triphosphatase (ATP7B) gene in patients and families with Wilson disease. Eighteen mutations, of which 7 were novel, and 11 polymorphisms, of which 3 were novel, were identified. These clinical-molecular correlations are extremely valuable to map the diversity of allelic mutations in this treatable neurological genetic disorder.
Attention in Dementia With Lewy Bodies, Alzheimer Disease, and Elderly Controls
Ballard and colleagues carefully evaluate patients for attention impairment associated with dementia of the Alzheimer disease (AD) type or with the Lewy body variant of AD and diffuse Lewy body disease. Slowing of cognitive processing, attention, and fluctuations of attention are significantly more pronounced in patients with diffuse Lewy body disease and patients with AD on all measures of attention and fluctuating attention. Patients from both dementia groups were significantly more impaired than elderly controls for all comparisons of cognitive reaction time. Attention is the first step in memory acquisition, and these findings are of significant interest as they offer a means of studying memory impairment early in the sequence of events required for storage and retrieval.
This Month in Archives of Neurology. Arch Neurol. 2001;58(6):866–867. doi:10.1001/archneur.58.6.866
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