scholarly journals Initial evaluation of vertigo

2006 ◽  
Vol 59 (11-12) ◽  
pp. 585-590 ◽  
Author(s):  
Slobodanka Lemajic-Komazec ◽  
Zoran Komazec
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Balance Control ◽  
Vestibular Nucleus ◽  
Sensory Information ◽  
Semicircular Canals ◽  
Vestibular Nuclei ◽  
Spontaneous Nystagmus ◽  
Medial Longitudinal Fasciculus ◽  
Slow Phase

Dizziness is one of the most common reasons patients visit their physicians. Balance control depends on receiving afferent sensory information from several sensory systems: vestibular, optical and proprioceptive. Bioelectric signals, generated by body movements in the semicircular canals and in the otolithic apparatus, are transported via the vestibular nerve to the vestibular nucleus. All four vestibular nuclei, located bilaterally in medial longitudinal fasciculus, are linked with central nervous system structures. These central nervous system structures are involved in maintaining visual stability, spatial orientation and balance control. Nystagmus is a result of afferent signals balance disorders. Nystagmus due to peripheral lesions is conjugate nystagmus, because there is a bilateral central connection. Lesions above the vestibular nuclei induce deficits in synchronization and conjugation of eye movements, thus the nystagmus is dissociated. This paper shows that in peripheral vestibular disorders spontaneous nystagmus is rhythmic, associated, horizontal-rotatory or horizontal, with subjective sensation of dizziness which decreases with time and harmonic signs whose direction coincides with the slow phase of nystagmus and it is associated with mild disorders during pendular stimulation with statistically significant vestibular hypofunction. Spontaneous nystagmus in central vestibular lesions is severe, dissociated, horizontal, rotatory or vertical, without changes related to optical suppression; if vestibular symptoms are present, they are non-harmonic. In central disorders, findings after thermal stimulation are either normal or pathological, with dysrhythmias and inhibition in pendular stimulation. This paper deals with differential diagnosis of vertigo based on anamnesis and clinical examination, as well as objective diagnostic tests. .

Probing the human vestibular system with galvanic stimulation

2004 ◽  
Vol 96 (6) ◽  
pp. 2301-2316 ◽  
Author(s):  
Richard C. Fitzpatrick ◽  
Brian L. Day
Keyword(s):  
Balance Control ◽  
Semicircular Canals ◽  
Vestibular Nuclei ◽  
Vestibular Stimulation ◽  
Otolith Organs ◽  
Sources Of Information ◽  
Electrophysiological Studies ◽  
Human Balance ◽  
Cortical Inputs ◽  
Vestibular Organs

Galvanic vestibular stimulation (GVS) is a simple, safe, and specific way to elicit vestibular reflexes. Yet, despite a long history, it has only recently found popularity as a research tool and is rarely used clinically. The obstacle to advancing and exploiting GVS is that we cannot interpret the evoked responses with certainty because we do not understand how the stimulus acts as an input to the system. This paper examines the electrophysiology and anatomy of the vestibular organs and the effects of GVS on human balance control and develops a model that explains the observed balance responses. These responses are large and highly organized over all body segments and adapt to postural and balance requirements. To achieve this, neurons in the vestibular nuclei receive convergent signals from all vestibular receptors and somatosensory and cortical inputs. GVS sway responses are affected by other sources of information about balance but can appear as the sum of otolithic and semicircular canal responses. Electrophysiological studies showing similar activation of primary afferents from the otolith organs and canals and their convergence in the vestibular nuclei support this. On the basis of the morphology of the cristae and the alignment of the semicircular canals in the skull, rotational vectors calculated for every mode of GVS agree with the observed sway. However, vector summation of signals from all utricular afferents does not explain the observed sway. Thus we propose the hypothesis that the otolithic component of the balance response originates from only the pars medialis of the utricular macula.

scholarly journals Convergence of linear acceleration and yaw rotation signals on non-eye movement neurons in the vestibular nucleus of macaques

2018 ◽  
Vol 119 (1) ◽  
pp. 73-83 ◽  
Author(s):  
Shawn D. Newlands ◽  
Ben Abbatematteo ◽  
Min Wei ◽  
Laurel H. Carney ◽  
Hongge Luan
Keyword(s):  
Eye Movement ◽  
Multisensory Integration ◽  
Vestibular Nucleus ◽  
Semicircular Canals ◽  
Linear Acceleration ◽  
Vestibular Nuclei ◽  
Otolith Organs ◽  
Angular Rotation ◽  
Sensory Signals ◽  
Nonlinear Integration

Roughly half of all vestibular nucleus neurons without eye movement sensitivity respond to both angular rotation and linear acceleration. Linear acceleration signals arise from otolith organs, and rotation signals arise from semicircular canals. In the vestibular nerve, these signals are carried by different afferents. Vestibular nucleus neurons represent the first point of convergence for these distinct sensory signals. This study systematically evaluated how rotational and translational signals interact in single neurons in the vestibular nuclei: multisensory integration at the first opportunity for convergence between these two independent vestibular sensory signals. Single-unit recordings were made from the vestibular nuclei of awake macaques during yaw rotation, translation in the horizontal plane, and combinations of rotation and translation at different frequencies. The overall response magnitude of the combined translation and rotation was generally less than the sum of the magnitudes in responses to the stimuli applied independently. However, we found that under conditions in which the peaks of the rotational and translational responses were coincident these signals were approximately additive. With presentation of rotation and translation at different frequencies, rotation was attenuated more than translation, regardless of which was at a higher frequency. These data suggest a nonlinear interaction between these two sensory modalities in the vestibular nuclei, in which coincident peak responses are proportionally stronger than other, off-peak interactions. These results are similar to those reported for other forms of multisensory integration, such as audio-visual integration in the superior colliculus. NEW & NOTEWORTHY This is the first study to systematically explore the interaction of rotational and translational signals in the vestibular nuclei through independent manipulation. The results of this study demonstrate nonlinear integration leading to maximum response amplitude when the timing and direction of peak rotational and translational responses are coincident.

scholarly journals Wall-eyed bilateral internuclear ophthalmoplegia (webino syndrome) and myelopathy in pyoderma gangrenosum

1990 ◽  
Vol 48 (4) ◽  
pp. 497-501 ◽  
Author(s):  
Marco Aurélio Lana ◽  
Paulo Roberto R. Moreira ◽  
Leonardo B. Neves
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Pyoderma Gangrenosum ◽  
Medial Longitudinal Fasciculus ◽  
Sensory Level ◽  
Internuclear Ophthalmoplegia ◽  
Central Nervous System Vasculitis ◽  
Exact Location ◽  
Vascular Occlusive Disease ◽  
Ocular Convergence

A 35-year-old female with pyoderma gangrenosum developed paraparesis with a sensory level at L1. Three months later she complained of diplopia and was found to have bilateral internuclear ophthalmoplegia with exotropia and no ocular convergence. The term Webino syndrome has been coined to design this set of neuro-opthalmologic findings. Although it was initially attributed to lesions affecting the medial longitudinal fasciculus and the medial rectus subnuclei of the oculomotor complex in the midbrain the exact location of the lesion is still disputed. In the present case both myelopathy and Webino syndrome were probably due to vascular occlusive disease resulting from central nervous system vasculitis occurring in concomitance to pyoderma gangrenosum.

Aging as a Compounding Variable in the Study of CNS Plasticity

1974 ◽  
Vol 32 ◽  
pp. 36-37
Author(s):  
J. E. Johnson ◽  
R. A. Yoesle ◽  
W. R. Mehler
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Vestibular Nucleus ◽  
Experimental Manipulation ◽  
Experimental Results ◽  
Ultrastructural Changes ◽  
Lateral Vestibular Nucleus ◽  
Age Changes ◽  
The Central Nervous System ◽  
Time Gap

In chronic experiments using animals, the time gap between the experimental manipulation and gathering the data (sacrificing the animal) may be quite large. In studies of plasticity in the central nervous system, utilizing as a model the lateral vestibular nucleus in the rat, we have found that there are a number of unusual ultrastructural changes that appear to occur at different ages. Data will be presented to show certain features of these normally occurring age changes that might easily be misinterpreted as experimental results.

The Kinetics of Sodium Transfer in the Central Nervous System of the Cockroach, Periplaneta Americana L

1961 ◽  
Vol 38 (4) ◽  
pp. 737-746
Author(s):  
J. E. TREHERNE
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Periplaneta Americana ◽  
Slow Phase ◽  
Second Phase ◽  
Sodium Ions ◽  
Rapid Phase ◽  
Fast Phase ◽  
The Central Nervous System ◽  
Sodium Extrusion

1. The exchange of sodium ions in the cockroach central nervous system has been studied by following the escape of 24Na from isolated abdominal nerve cords, single connectives and ganglia. Particular attention was paid to the initial rapid exchanges of sodium. 2. The escape of sodium ions occurred as a two-stage process, an initial rapid phase eventually giving way to a slower exponential phase of sodium loss. The fast phase of efflux was not affected by the presence of 2:4-dinitrophenol, although this poison significantly reduced the second slow phase of sodium extrusion. 3. The initial fast phase is attributed to a rapid diffusion from an extracellular space, demonstrated by 14C-inulin; the second phase is identified as the slower extrusion from the cellular components of the central nervous system.

Are There Parallel Channels in the Vestibular Nerve?

Physiology ◽  
1998 ◽  
Vol 13 (4) ◽  
pp. 194-201 ◽  
Author(s):  
Ellengene H. Peterson
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Sensory Information ◽  
Primary Afferents ◽  
Vestibular Nerve ◽  
Functional Roles ◽  
The Central Nervous System ◽  
Parallel Channels

A popular concept in neurobiology is that sensory information is transmitted to the central nervous system over parallel channels of neurons that play different functional roles. But alternative organizing schemes are possible, and it is useful to ask whether some other framework might better account for the diversity of vestibular primary afferents.

scholarly journals Balance control strategies during perturbed and unperturbed balance in standing and handstand

2017 ◽  
Vol 4 (7) ◽  
pp. 161018 ◽  
Author(s):  
Glen M. Blenkinsop ◽  
Matthew T. G. Pain ◽  
Michael J. Hiley
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Control Strategy ◽  
Inverted Pendulum ◽  
Mixed Strategy ◽  
Balance Control ◽  
Control Strategies ◽  
Ankle Strategy ◽  
The Central Nervous System ◽  
Fixed Orientation

Insights into sensorimotor control of balance were examined by the assessment of perturbed and unperturbed balance in standing and handstand postures. During perturbed and unperturbed balance in standing, the most prevalent control strategy was an ankle strategy, which was employed for more than 90% of the time in balance. During perturbed and unperturbed balance in handstand, the most prevalent control strategy was a wrist strategy, which was employed for more than 75% of the time in balance. In both postures, these strategies may be described as a single segment inverted pendulum control strategy, where the multi-segment system is controlled by torque about the most inferior joint with compensatory torques about all superior joints acting in the same direction to maintain a fixed orientation between superior segments. In contrast to previous literature, surprisingly little time was spent in a mixed strategy, representing less than 1% of time in standing balance and approximately 2% of time in handstand balance. Findings indicate that although the central nervous system may employ a number of control strategies during a trial, these strategies are employed individually rather than simultaneously.

Cortical Visual Impairment in Young Children with Multiple Disabilities

1990 ◽  
Vol 84 (5) ◽  
pp. 200-203 ◽  
Author(s):  
M.T. Morse
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Visual Impairment ◽  
Sensory Information ◽  
Multiple Disabilities ◽  
Complex Interaction ◽  
Handicapped Children ◽  
Cortical Visual Impairment ◽  
System Functioning ◽  
Visually Handicapped

Teachers of visually handicapped children are seeing an increased frequency in referrals of young, multiply handicapped children with cortical visual impairment. The use of the residual visual capacity in these children is related to their ability to neurologically process and understand environmental sensory information. The complex interaction of the visual process, central nervous system functioning, and environmental stimuli has major implications for effective educational planning.

Grasp stability during manipulative actions

1994 ◽  
Vol 72 (5) ◽  
pp. 511-524 ◽  
Author(s):  
Roland S. Johansson ◽  
Kelly J. Cole
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Precision Grip ◽  
Sensory Information ◽  
Parameter Control ◽  
Control Mechanisms ◽  
Control Processes ◽  
Grasp Stability ◽  
The Central Nervous System ◽  
Fingertip Forces

The control of adequate contact forces between the skin and an object (grasp stability) is examined for two classes of prehensile actions that employ a precision grip: lifting objects that are "passive" (subject only to inertial forces and gravity) and preventing "active" objects from moving. For manipulating either passive or active objects the relevant fingertip forces are determined by at least two control processes. "Anticipatory parameter control" is a feedforward controller that specifies the values for motor command parameters on the basis of predictions of critical characteristics, such as object weight and skin–object friction, and initial condition information. Through vision, for instance, common objects can be identified in terms of the fingertip forces necessary for a successful lift according to previous experiences. After contact with the object, sensory information representing discrete mechanical events at the fingertips can (i) automatically modify the motor commands, (ii) update sensorimotor memories supporting the anticipatory parameter control policy, (iii) inform the central nervous system about completion of the goal for each action phase, and (iv) trigger commands for the task's sequential phases. Hence, the central nervous system monitors specific, more or less expected peripheral sensory events to produce control signals that are appropriate for the task at its current phase. The control is based on neural modelling of the entire dynamics of the control process that predicts the appropriate output for several steps ahead. This "discrete-event, sensor-driven control" is distinguished from feedback or other continuous regulation. Using these two control processes, slips are avoided at each digit by independent control mechanisms that specify commands and process sensory information on a local, digit-specific basis. This scheme obviates explicit coordination of the digits and is employed when independent nervous systems lift objects. The force coordination across digits is an emergent property of the local control mechanisms operating over the same time span.Key words: precision grip, hand, grasp stability, grasp force, tactile afferents.

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