Canadian Journal of Neurological Sciences
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A 14 year old boy with scapuloperoneal muscular atrophy, pes cavus, areflexia and distal sensory loss (Davidenkow syndrome) is described. Nerve conduction velocities were diminished. Sural nerve biopsy demonstrated a reduction in the number of myelinated fibers and early “onion-bulb” formation. These observations support the hypothesis that the scapuloperoneal amyotrophy associated with distal sensory loss may represent a variant of type I hereditary motor sensory neuropathy.
Foreign Accent Syndrome (FAS) is a rare acquired syndrome following neurological damage that results in articulatory distortions that are commonly perceived as a “foreign” accent. The nature of the underlying deficit of FAS remains controversial. We present the first reported Canadian case study of FAS following a stroke. We describe a stroke patient, RD, who suffered an acute infarction to the left internal capsule, basal ganglia and frontal corona radiata. She was diagnosed as having FAS without any persistent aphasic symptoms. Family, friends, and health care professionals similarly described her speech as sounding like she had a Canadian East Coast accent, a reported change from her native Southern Ontario accent.
An investigation of this case was pursued, incorporating neuroimaging, neuropsychological and speech pathology assessments, and formalized linguistic analyses.
Linguistic analyses confirmed that RD’s speech does in fact have salient aspects of Atlantic Canadian English in terms of both prosodic and segmental characteristics. However, her speech is not entirely consistent with an Atlantic Canadian English accent.
The fact that RD’s speech is perceived as a regional variant of her native language, rather than the “generic foreign accent” of FAS described elsewhere, suggests that the perceived “foreignness” in FAS is not primarily due to dysfluencies which indicate a non-native speaker, but rather due to very subtle motor-planning deficits which give rise to systemic changes in specific phonological segments. This has implications for the role of the basal ganglia in speech production.
The kindling effect is a relatively permanent alteration in brain function which results from repeated electrical or chemical stimulation and culminates in the appearance of electrographic and behavioral convulsions whenever the original stimulus is reapplied. The effect results from tetanic activation in the anterior cortex, limbic system or associated areas of the adult mammalian brain, and the lasting alterations are transynaptic and quite widespread. They are based in part on synaptic facilitation, and they are accompanied by specific alterations in normal behavior. In these and other respects, kindling is analogous to normal learning. It is possible that the stored component (engram) of kindling involves the same physiological mechanism as the engram of normal long term memory. Morphological study of identified synapses has not provided conclusive evidence for an anatomical substrate of kindling, but physiological experiments demonstrate a lasting potentiation of the excitatory postsynaptic potential.
Secondary epileptogenesis was induced in the hippocampal cortex of the paralyzed bullfrog by means of localized, unilateral, intermittent electrical stimulation (kindling). Stimuli were designed to yield a brief but definite after-discharge. In control animals a progressive increase in after-discharge duration occurred at the 1° (stimulated) site and then at the 2° site (contralateral hippocampus). Spontaneous epileptiform potentials (SEP's) occurred between stimuli, eventually independently on both sides.
Cycloheximide (50 mg/kg) caused 88-99% reduction in protein synthesis, measured by14C-leucine incorporation into brain protein. Cycloheximide-treated animals revealed no evidence of progressive prolongation of after-discharge duration when subjected to the kindling procedure (p = 0.1205xl0-7). SEP's were reduced in the cycloheximide-treated animals, and confined to 1° hemisphere (p=0.6xl0-10).
Since cycloheximide did not disturb normal electrogenesis or disrupt the after-discharges, this experiment distinguishes processes dependent upon electrical events from those requiring macromolecular synthesis. Protein synthesis seems critical to the emergence of spontaneous and autonomous epileptiform behavior of neural aggregates.
To date, few pediatric series of neurofibromatosis type 1 (NF-1) have been described in the literature even though it is the most frequently encountered phakomatosis.
We reviewed 987 charts of pediatric patients with a presumptive diagnosis of NF-1 who were evaluated at Ste-Justine hospital from January 1, 1991 to July 31, 2002. Patients who presented with two or more cardinal criteria were diagnosed with NF-1. Clinical and laboratory data were retrospectively collected, including: demographics, neuroimaging and presence or absence of associated symptoms or signs of NF-1.
A total of 279 patients were diagnosed with NF-1. The mean age at diagnosis was 3.4 years. Ninety-nine percent of the patients had café au lait spots and 47% had a first degree relative with NF-1. Almost 60 percent (59.6%) of those seen by an ophthalmologist had Lisch nodules. Optic glioma was found in in 14.7%, cutaneous neurofibromas in 38.4%, plexiform neurofibromas in 24.7%, neurofibrosarcoma in 1.8%, learning disabilities in 39%, attention deficit disorder in 40.5%, osseous dysplasias in 7.2%, pseudoarthrosis in 3.6%, precocious puberty in 3.2% and short stature in 17.9%. Magnetic resonance, when performed, showed hyperintense T2 lesions in 87.1% of cases. The mean period of follow-up was 7.4 years.
Neurofibromatosis type 1 is a multisystemic disorder associated with increased risk of malignancy. It can be diagnosed at a very young age and clinical follow-up is advised. To our knowledge, this is the largest single center study of NF-1 in a pediatric population.
A variety of peripheral nerve disorders may be associated with chronic renal failure. The polyneuropathy due to uremic toxins is a distal, motor and sensory polyneuropathy in which there is segmental demyelination, axonal degeneration, and segmental remyelination. The nature of the uremic toxin and the underlying mechanism of these changes is unknown.
The incidence in patients with “endstage” renal disease has fallen in recent years, severe cases now being rare, perhaps due to refinements in chronic hemodialysis, transplantation, and other therapies. However, while chronic hemodialysis stabilizes uremic neuropathy, manipulation of hemodialysis schedules may not alter its course, according to current assessment. Successful renal transplantation improves both the clinical and electrophysiological signs, even in severe uremic neuropathy.
Over the past fifty years considerable clinical evidence has accrued to demonstrate involvement of the cerebral cortex in cardiac function. Hemispheric stroke is often associated with electrocardiographic (ECG) evidence of cardiac repolarisation abnormalities. In addition strokes of all types are associated with specific pathological changes in the ventricular myocardium (myocytolysis). These effects are not attributable to concomitant cardiac ischemic disease in the majority of cases. The insular cortex has recently been shown to contain a site of cardiac representation. Prolonged stimulation of this region in the rat produces ECG and cardiac pathological changes similar to those observed after human stroke. It is suggested that middle cerebral artery stroke in certain cases either directly or indirectly leads to insular disinhibition, and increased autonomic activity represented by cardiac changes which significantly influence prognosis.
Although numerous etiological or triggering factors have been suggested in sudden infant death syndrome (SIDS), the underlying mechanism of death is ultimately cardiac and/or respiratory in nature. As there is no evidence of lung or heart abnormalities, attention has focussed on the neural control of respiration and cardiac function. It is important to appreciate the methodological limitations involved in utilizing autopsy material and the criteria for selection of appropriate controls. This report reviews the pathological evidence for developmental delay in SIDS emphasizing delay of neural maturation of both myelination and synapses. Other abnormalities of the nervous system apparently associated with hypoxia-ischemia such as brainstem astrogliosis are also discussed. The occurrence of SIDS at a precise age together with our preliminary studies indicate that neural developmental delay is an important link in the chain of events leading to SIDS.
Growing evidence showed that coronavirus disease 2019 (COVID-19) infection may present with neurological manifestations. This review aimed to determine the neurological manifestations and complications in COVID-19.
We conducted a systematic review and meta-analysis that included cohort and case series/reports involving a population of patients confirmed with COVID-19 infection and their neurologic manifestations. We searched the following electronic databases until April 18, 2020: PubMed, Embase, Scopus, and World Health Organization database (PROSPERO registration number: CRD42020180658).
From 403 articles identified, 49 studies involving a total of 6,335 confirmed COVID-19 cases were included. The random-effects modeling analysis for each neurological symptom showed the following proportional point estimates with 95% confidence intervals: “headache” (0.12; 0.10–0.14;
This review revealed that neurologic involvement may manifest in COVID-19 infection. What has initially been thought of as a primarily respiratory illness has evolved into a wide-ranging multi-organ disease.
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