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This Month in Archives of Neurology
Arch Neurol. 2002;59:1362-1363.
Neurology: Then, Now, and in the Future
"It is tough to make predictions—particularly about the future,"
said Yogi Berra. Guy M. McKhann, MD, (SEE ARTICLE) 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 (SEE ARTICLE) provide
interesting new data showing increased ß-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, (SEE ARTICLE) provides editorial comment.
What Causes the Signs and Symptoms of Multiple Sclerosis?
Stephen G. Waxman, MD, PhD (SEE ARTICLE) 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 (SEE ARTICLE) 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 (SEE ARTICLE) 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.
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Average mean diffusivity () 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.
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Dementia in Parkinson Disease
Summerfield et al (SEE ARTICLE) , 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 (SEE ARTICLE) 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 (SEE ARTICLE) 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 (SEE ARTICLE) 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 (SEE ARTICLE) 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 (SEE ARTICLE) 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 (SEE ARTICLE) 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.
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