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Niemann-Pick disease is a disorder of sphingomyelin metabolism, which produces organomegaly and progressive generalized neurologic dysfunction. In two brothers with Niemann-Pick disease type C brain stem auditory evoked potentials (BAEPs) produced prolongation of waves I-III interpeak latencies.
A male infant with neuroaxonal dystrophy of neonatal onset is described. He was hypertonic, and exhibited horizontal nystagmus, occasional tremulous movements of the head and extremities, and an absence of waves III through V on auditory brain stem response examination. An autopsy at age 11 months revealed spheroid formation that was predominant in the cerebellum and brain stem, and dysmyelination that was mainly seen in the white matter of the cerebellum. This is in contrast with most of the previously reported patients of infantile neuroaxonal dystrophy in which these changes were evenly distributed throughout the central, peripheral and autonomic nervous systems.
Generalized epilepsy involves abnormally synchronized activity in large-scale neuronal networks. Burst firing of action potentials is a potent mechanism for increasing neural synchrony and is thought to enhance cortical and thalamic rhythmic network activity. Absence seizures, a form of generalized epilepsy, occur in children as brief 5- to 10-s periods of behavioral arrest associated with massive 3- to 4-Hz spike-wave discharges in cortical and thalamic networks. Prior research has shown that enhanced burst firing may be crucial for the transition from normal to epileptic activity. Can enhanced burst firing in one region of the nervous system, such as the cortex, transform the entire thalamocortical network from normal activity to spike-and-wave seizures? Enhanced burst firing in corticothalamic neurons may increase gamma-aminobutyric acid-B (GABAB) receptor activation in the thalamus, leading to the slower, more synchronous oscillations seen in spike-and-wave seizures. Does "generalized" spike-wave activity homogeneously involve the entire brain, or are there crucial nodes that are more important than others for the generation and behavioral manifestations of generalized seizures? Animal and human data suggest that so-called generalized seizures involve selective thalamocortical networks while sparing others. A greater understanding of these molecular and network mechanisms will ultimately lead to improved targeted therapies for generalized epilepsy.
With the invention of magnetic resonance imaging (MRI) and the auditory evoked brain stem responses (AEBR), it has become possible to diagnose acoustic tumours while they are still small. As a result, it has become obvious that the clinical presentation of smaller lesions can be some-what different from what is considered typical of an acoustic neuroma. Likewise, whereas the sensitivity of auditory brain stem responses for larger tumours is good, the sensitivity for smaller tumours has recently been in doubt, particularly if the patient presents early in the course of the disease with only mild otologic complaints. A retrospective study of patients treated for small acoustic neuromas, defined as less than 1 cm extension into the cerebellopontine angle, was conducted to assess ABR results as well as the clinical and audiological presentation in these patients. Of the 70 patients included in the study, auditory brain stem responses were abnormal in 65 (93%), based on wave V latency prolongation and intra-aural latency differences. These would indicate that auditory brain stem responses are a valid screening test for acoustic neuromas, even in the early stages of development. The clinical presentation of patients with small acoustic tumours was similar to the presentation reported for acoustic neuromas in general, but with vertigo occurring more often in patients with smaller tumours. Several atypical patterns of hearing loss were seen in this population.
Recent advances in electrode design have helped to rekindle clinical interests in noninvasive electrocochleography--to enhance auditory brain stem response (ABR) recordings (namely, wave I) and to screen Meniere's disease. The salient feature of the response in suspected cases of endolymphatic hydrops is an unusually large summating potential (SP). Since the SP is a DC potential, conventional wisdom suggests the use of relatively low cutoff frequencies (i.e., long-time constants) for recording, but this may degrade the recording due to the presence of excessive low-frequency noise. However, the click-elicited SP also is a transient of relatively short duration, considering the characteristics of the click. This may permit more liberal high-pass filtering with acceptable wave-form distortion. This is a report of findings obtained using an analog model for SP generation and recordings from normal subjects using an electrode placed directly on the tympanic membrane. Responses were obtained using various low-frequency cutoffs. Cutoffs up to 30 Hz caused little distortion. Even in the face of considerable distortion at the highest cutoffs (100 and 300 Hz), the SP remained detectable and the SP:AP essentially unchanged. Therefore, higher filter settings may be used in recording the SP than commonly assumed, although the decreased amplitudes of the component potentials may not be tolerable under all clinical test conditions.
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Electrophysiological evidence for the critical band phenomenon in humans using event-related potentials has been sought for many years with conflicting results. Components Na and Pa of the middle-latency response (MLR) and wave V of the auditory brain-stem response (ABR) were simultaneously recorded in response to a two-tone complex varying in bandwidth from 76 Hz to 1012 Hz, centered at 2 kHz, and presented at an overall level of 85 dB SPL, in ten normal female subjects. Only the amplitude of Na showed an abrupt increase as bandwidth changed from 268 to 330 Hz, yielding an estimate of critical bandwidth in good agreement with previous behavioral estimates.
Isolated cortical venous thrombosis (CVT) is rare, and the discrepancy between clinical features and neuroradiologic findings has not been adequately emphasized. A thirty-one-year-old woman presented with focal seizures and occasionally secondary generalization. There was no focal neurologic deficit except for Todd's paralysis. Electroencephalography showed intermittent theta waves at the left frontoparietal area. Brain computed tomography (CT) and magnetic resonance imaging (MRI) disclosed a large lesion in the left frontoparietal area. An extensive occlusion of the superior cerebral veins of the left hemisphere with a patency of the dural sinuses was noted in the cerebral angiography. Eight months later, the CT hypodense lesion disappeared. Her neurologic status was stationary, but the seizures, mostly focal, still occurred occasionally. In this report, the authors emphasize the dissociation between minor clinical features and larger CT and MRI lesions in isolated CVT.
Guinea pigs were passively sensitized by sera containing antidinitrophenyl reaginic antibody and specifically challenged by dinitrophenyl-bovine serum albumin injected through the stylomastoid foramen. Nystagmus, head deviation, negative summating potentials on electrocochleography, and an increase of threshold and wave I peak latency on auditory brain stem response testing were observed after local challenge. These physiologic changes were reversible and resolved within several days. We also used Tranilast before the specific challenge. It is a blocking agent of chemical mediator release from mast cells. Negative summating potentials and head deviation were not observed after the use of this agent. In the animals that showed physiologic changes, we observed endolymphatic hydrops, mast cell degranulation, and eosinophil infiltration histologically in the challenged side of the inner ear. These results suggest that the physiologic and histologic changes provoked in the inner ear of the sensitized animals may have been induced by type I allergy.
A 5-year-old girl was admitted with a 3-day history of speech disorder and gait abnormality. She had been diagnosed with idiopathic epilepsy and was given phenytoin 2 months before admission to our hospital. On physical examination, she had severe lingual-facial-buccal extrapyramidal movements, slurred speech, and ataxic gait. During examination, she was repetitively scratching her scalp with her right hand every 30 to 60 seconds. Serum phenytoin level was 10 microg/mL (normal 8-20 microg/mL). Electroencephalography showed diffuse slow waves. Magnetic resonance imaging of the brain was normal. During hospitalization, her abnormal findings were thought to be attributable to phenytoin; it was immediately discontinued, and biperiden was initiated. After biperiden was administered, her abnormal movements markedly decreased; later, they almost completely disappeared. In conclusion, we would like to emphasize that severe dyskinesia can be observed during phenytoin therapy and that biperiden can be successfully used in the treatment of this unpleasant condition.
Different breathing pathologies (apneusis, gasping, Cheyne-Stokes breathing and Kussmaul breathing) were observed in anaesthetized rabbits and rats exposed to hypoxia at the altitude of 7500-8000 meters. Dominance of the high-voltage slow EKG activity (the delta-wave type) suggested deterioration of the brain functioning. Registration of impulse activities of the inspiration and expiration breathing neurons in medulla oblongata revealed a higher tolerance of the inspiration neurons to severe hypoxia which is attributed to the metabolic specifics and functional heterogeneity of these neurons. Character of the neuron impulsation is indicative of the reflectory effects of hemo- and mechanoreceptors, and the direct effects of different humoral substances resulting in impairment of the central control of pacemakers and breathing pathologies. It appears that various breathing pathologies in altitude chambers and mountains are triggered by the hypoxic factor. However, no dependence was established either between the initial breathing rhythm (before "ascent") and various types of breathing at the "altitude" or these types of breathing and magnitude of hypoxia.
Somatosensory evoked potentials (SEP) are responses which appear under the influence of sensory stimuli, producing a series of bioelectric changes in the peripheral and central nervous system. Particular components of SEP are recorded from the stimulation point-at the wrist--of the examined median nerve through the brachial plexus, spinal cord and subcortical structures to gyrus postcentralis in the brain. The source of N 20 wave is found in the primary sensory cortex, while P 25 is the response from the somatosensory region of the cerebral cortex in the parietal lobe, in the region responsible for the upper limb. N9 deflection is generated by the stimulation wave, going along the brachial plexus (Erb's point). 50 children and adolescents at the age of 8-16 were examined. In the analysis of the obtained results the influence of sex, age, height, the length of upper limbs, head circumference and temperature of the examined patients' skin was taken into consideration. SEP recording was performed with the use of Multiliner equipment, (Toennies, Germany) according to the recommendation of the International Federation of Clinical Neurophysiology. The responses obtained during the stimulation of median nerves were recorded with the use of surface electrodes located at the head according to 10-20 system in C'3 and C'4 points and from the active electrode EP situated at Erb's point above the brachial plexus. Latencies and amplitude, component of short latency (N20, P25, N9) time differences of their appearance and the speed of nerve impulse conduction along stimulated fibres were analysed. There were significant relations found between latency of N9 and N20 waves and age, height and the length of limbs in examined patients but there were no relations found between P 25 appearance and the elements mentioned above. It was stated that the head circumference did not influence time of cortical waves appearance. Moreover, it was not found that growth of skin temperature within the range of 30-36 degrees C significantly influenced the acceleration of nerve impulse conduction along stimulated fibres. It was proved that SEP is a precise and non-invasive method which may be applied in children and adolescents. Interpretation of the obtained results requires consideration of anthropological parameters that change during the developmental age.
A rare case of neurosarcoidosis presenting with psychomotor seizure is reported. A 35-year-old woman was admitted to our ward for further evaluation of syncopal attacks and suspected sarcoidosis. The patient had a history of syncopal attacks for about 15 years prior to admission; however, the pathogenesis was not clarified in spite of various examinations. Three months prior to admission, left peripheral facial nerve palsy, bilateral hypopion and bilateral hilar lymphadenopathy on plain chest film were noted at the departments of neurosurgery and ophthalmology of our hospital. She was referred and admitted to our ward. The diagnosis of sarcoidosis was made by scalene node biopsy. The syncopal attacks could not be controlled by several anticonvulsant agents. Although no significant findings were observed on brain CT and cerebral angiography, spike wave was revealed on electroencephalography (EEG) in the parieto-temporal lead. The syncopal attacks were diagnosed psychomotor seizures from both the clinical features and the EEG findings. We concluded that syncope was caused by neurosarcoidosis. The patient was prescribed steroid with much improvement of these symptoms.
Aim of the present study was to investigate the tonotopic reorganization of the primary auditory cortex in otosclerotic patients following functional stapedioplasty. Characteristics of auditory cortex activation have been evaluated in a series of 10 otosclerotic patients before and after surgery. In these patients, a magnetoencephalographic recording of evoked magnetic fields has been performed by means of tone-burst monoaural stimulation with frequency octaves between 250 and 2000 Hz. Brain topography of cortex response generators (wave N100m) in patients with otosclerosis has been compared with that observed in a control group of 10 healthy subjects: changes before and after surgery have also been correlated with the functional result as far as concerns improvement in hearing. A significant reduction has been observed in the cortical tonotopic extension in response to the acoustic stimulus in patients "pre-surgery" in comparison with controls: after surgery, tonotopic mapping showed an increase, dimensions becoming comparable to those in control subjects. This increase in size was found to be significantly correlated with duration of the post-operative period. Data emerging from the present study suggest that the cortical auditory areas in man are involved in a "plastic" functional reorganization following changes in the receptor or peripheral deprivation. Reduction in the cortical tonotopic mapping resulting from prolonged lowering of auditory "input" is modified by reorganization of the cortex after the recovery of auditory function: this process occurs over a period of a few weeks.
We report a patient with dentatorubral-pallidoluysian atrophy (DRPLA). She developed normally until the age of 6 month, when she could sit by herself. However, her psychomotor development was subsequently slow with gradual appearance of equilibrium disturbances and involuntary movements such as polymyoclonia and chorea. Her development deteriorated after myoclonic seizures developed at 4.5 years of age. Electroencephalograms showed semi-continuous bursts of diffuse irregular spike-wave complexes and MRI of the brain showed atrophy of the cerebellum and brainstem, and high signal intensities in the posterior periventricular triangle portion on T2-weighted images. Gene analysis performed at the age of 6 years revealed an expanded CAG repeat (17/74) at the DRPLA locus. The CAG repeat size was larger in this case than in cases of the adult and juvenile types with later onset, suggesting a correlation between repeat length and age at onset. Genetic examination of the family members was not performed because of her mother's fear and emotional confusion.
The present paper enlightens a new point of view on brain homeostasis and communication, namely how the brain takes advantage of different chemical-physical phenomena such as pressure waves, and temperature and concentration gradients to allow the homeostasis of the brain internal milieu as well as some forms of intercellular communications (volume transmission, VT) at an energy cost much lower than the classical synaptic transmission (the prototype of wiring transmission, WT). The possible melanocortin control of uncoupling protein 2 (UCP2) expression (hence of local brain temperature gradients) has been studied in relation to food intake in male Wistar rats. Osmotic minipumps were subcutaneously (sc) implanted in the midscapular region for intracerebroventricular (icv) infusion. The control rats received an icv infusion of 0.5 microl/h of artificial cerebrospinal fluid (ACSF), while experimental rats received either an icv infusion of 0.16 nmol/h of HS024 or of 0.16 nmol/h of adrenocorticotropin-(1-24) [ACTH-(1-24)]. The ACTH-treated group ate significantly less than the ACSF-treated group during the first three days of infusion, while, subsequently, food intake of the two groups was similar. On the other hand, the HS024-treated group ate significantly more (up to 153% of the control value) than ACSF- and ACTH-treated rats during the entire period. UCP2 mRNA analysis in arcuate nuclei of ACTH, HS024 and ACSF-treated animals showed a significant 75% decrease (p<0.05 vs saline) of the total specific mRNA level in the HS024-treated group vs ACSF-treated animals (control group), while no significant change was observed between ACTH- and ACSF-treated animals. Melanocortin antagonist HS024 via blockade of MCR4 increases food intake and via a reduction of UCP2 expression enhances the food consumption ratio. This result underlines the fact that UCP2 expression and food intake can be differentially regulated. In other words, via a peptidergic control the central nervous system (CNS) can modulate the energy stored from the amount of the food that the animal has eaten and also uncouple the thermal micro-gradients (dependent on UCP2 expression) and hence the VT-signal micro-migrations from the food intake. It should also be noticed that the control of the thermal gradients affects also the neuronal firing rate and hence the transmitter release (likely above all the release of peptides such as neuropeptide Y (NPY), melanin-concentrating hormone (MCH) and beta-endorphin, e.g., in the arcuate nucleus representing signals relevant to energy homeostasis). Thus, WT and VT are both modulated by peptidergic signals that affect thermal gradients.
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