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Neurology: Then, Now, and in the Future
"It is tough to make predictions—particularly about the future," said Yogi Berra. Guy M. McKhann, MD, offers his predictions for the future of neurology, reflecting on the 50th Anniversary of the National Institute of Neurological Diseases and Stroke (Bethesda, Md). He outlines his view of "The Coming Interventional Revolution," which will change the practice of neurology by emphasizing prevention, protection of the brain, and promotion of recovery. We are provided a glimpse of the world of neurology in 2025 and beyond, as he sees it!
Explaining Amyloid Burden in Alzheimer Disease
Fukumoto et al provide interesting new data showing increased β-secretase (BACE) activity and protein in patients with late-onset sporadic Alzheimer disease (AD) compared with controls. Increased total amyloid burden in AD may be in part due to increased BACE activity and supports the need to develop BACE inhibitors that may slow the progression of disease. These data explain further the molecular basis of dementia in AD and provide new evidence for BACE inhibitors as a potential new therapeutic intervention. Roger N. Rosenberg, MD, provides editorial comment.
What Causes the Signs and Symptoms of Multiple Sclerosis?
Stephen G. Waxman, MD, PhD provides a review of the role of ion channels, neuronal dysfunction, and molecular events that contribute to the pathogenesis of multiple sclerosis (MS). Adaptive and maladaptive ion channel defects, ectopic distribution of ion channels, and transcriptional channelopathies are explained in the context of demyelination, axonal function, and axonal loss. New cellular, electrophysiologic, and molecular concepts and definitions are now in place, providing key innovative insights into the cause of MS symptoms and signs.
"Second Wind" in McArdle Disease
Haller and colleagues have elegantly evaluated the oxidative implications of the spontaneous "second wind" and variables that influence the development of this typical feature of McArdle disease. In general, they find that these features are due to substrate-dependent increases in muscle oxidative capacity. These results provide a framework for differentiating symptoms related to impaired aerobic glycogenolysis from those related to deficient anaerobic glycogenolysis in McArdle disease.
Normal-Appearing White and Gray Matter in Multiple Sclerosis
Rovaris et al have assessed the extent of multiple sclerosis (MS) pathologic characteristics in normal-appearing white and gray matter of the brain using diffusion tensor (DT) magnetic resonance imaging (MRI). They document in detail that in patients with primary progressive MS, normal-appearing white and gray matter are not spared. Their findings extend the degree of sensitivity and involvement in the MS process and offer a means to quantitatively follow the natural degree of illness and the effectiveness of therapeutic intervention.
Average mean diffusivity (D̄) histograms of the normal-appearing white matter (A) and the normal-appearing gray matter (B) from healthy control subjects, patients with primary progressive multiple sclerosis (PPMS), and patients with secondary progressive multiple sclerosis (SPMS). Compared with healthy controls, a reduction of the histogram peak height (which reflects the amount of "truly" normal tissue) can be observed for the patients with PPMS and SPMS, and is more pronounced in the latter group.
Dementia in Parkinson Disease
Summerfield et al, using magnetic resonance spectroscopy (MRS), have systematically investigated the utility of proton MRS in distinguishing idiopathic Parkinson disease (PD) with and without dementia. They find that the levels of the neuronal marker N-acetylaspartate (NAA) were significantly reduced in the occipital region of the brain in the group with PD and dementia relative to patients with PD and controls. Further, NAA values correlated with neuropsychologic performance but not with severity of motor impairment. Thus, MRS has a clear clinical role in the evaluation and diagnosis of patients with PD. The biological basis of this observation remains to be determined but may be related to Lewy body disease in subcortical regions that project or influence biochemical events in the occiptial lobe.
Consequences of Coronary Artery Bypass Grafting
McKhann and colleagues have determined the incidence, consequences, and predictive factors for encephalopathy and stroke following coronary artery bypass grafting (CABG) in a series of patients. A prospective evaluation of 2771 patients operated on between January 1997 and December 2000 was conducted. In general, they found that encephalopathy or stroke is associated with significant increases in hospital length of stay and mortality after CABG and that patients at higher risk for these outcomes can be identified prior to surgery.
Prion Disease of the Peripheral Nervous System
Niewiadomska et al have studied peripheral nerve function by electrophysiologic studies and by neuropathologic examination in patients with Creutzfeldt-Jakob disease (CJD). They found a significant degree of abnormal peripheral nerve function or structure in these patients with sporadic CJD. Clearly, prion disease involves the peripheral nervous system and should be considered in the evaluation and diagnosis of patients suspected as potentially having CJD.
Electrocardiographic Findings After Transient Ischemic Attack
Elkins et al used electrocardiograms to evaluate 1327 patients with transient ischemic attack (TIA) and found cardiac events in 2.9%, strokes in 10.9%, recurrent TIAs in 13.7%, and deaths in 2.6% during a 90-day follow-up. Short-term cardiac morbidity is substantial after TIA, with atrial fibrillation occurring in a significant portion of patients with TIA. It is a useful and practical study to emphasize the cardiac issues that arise after a TIA.
Outcome Measures for Pediatric Spinal Muscular Atrophy
Iannacconne et al evaluated 12 children, aged 2 to 14 years, with spinal muscular atrophy (SMA) using 4 outcome measures: Quantitative Muscle Test, Gross Motor Function, Pulmonary Function Test, and Quality of Life. They found that a composite evaluation involving all of the included evaluative tests rather than just 1 test for quantitative muscle strength was important. A tool that measures motor function may be more useful and reliable in clinical trials of childhood SMA than one that measures quantitiative muscle strength alone.
Preservation of Directly Stimulated Muscle Strength in Hemiplegic Stroke
Landau and Sahrmann compared contraction strengths induced by maximal tetanic electrical stimulation of impaired and contralateral muscles in patients with hemiplegic stroke. The elicited force of the tibialis anterior muscle with direct electrical stimulation was not significantly different between the limbs of normal subjects and patients who were stroke impaired. Thus, as a corollary, modes of exercise therapy that focus primarily on direct strengthening of striated musculature are strategically questionable. Weakness is a central nervous system issue related to the stroke, and "the central disability of the upper motor neuron syndrome is a failure of rapid coordinated adjustment of graded high-frequency motoneuron firing in purposeful complex synergies." Landau and Sahrmann have defined, in a direct manner, the separate issues of the upper motor neuron and muscle components in generating strength as evidenced in the patient with stroke.
Williams Syndrome and the Visual Cortex
Galaburda and colleagues have found that cell measurements differ in the peripheral visual cortical fields in patients with Williams syndrome, with significantly smaller, more closely packed cells in some layers. These differences in cell-packing density and neuronal size may be related to visuospatial deficits in this population.
This Month in The Archives of Neurology. Arch Neurol. 2002;59(9):1362–1363. doi:10.1001/archneur.59.9.1362
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