Botulinum Toxin as an Alternative to Treat the Spasm of the Near Reflex

We describe the case of an eight-year-old girl with complaints of headaches and blurred vision (uncorrected visual acuity: 0.1 decimal) that showed on examination miotic pupils, pseudomyopia, no ocular motility restrictions, and no associated neurological disease. After initial treatment with cyclopentolate for two months, pseudomyopia persisted with an intermittent and variable esotropia. Spectacles of +1 both eyes and atropine 1% one drop daily were then prescribed. The situation improved and remained stable for several weeks, with pseudomyopia and esotropia reappearing later. Finally, botulinum toxin (2.5 iu Botox®) was injected in the medial rectus muscle on two occasions and a visual therapy program based on the stimulation of fusional divergence, diplopia, and stereopsis consciousness was recommended. This prescription was combined with the use of atropine during the first few weeks. Orthotropia and corrected distance visual acuity of 1.0 were found three months after treatment. The evolution and clinical results of this case report suggest that botulinum toxin in combination with other therapeutic alternatives may be useful in the treatment of spasm of the near reflex.

Impacts fonctionnels du traumatisme craniocérébral léger sur la vision et l'équilibre postural chez l'adulte

Le traumatisme craniocérébral léger (TCCL) a des effets complexes sur plusieurs fonctions cérébrales, dont l’évaluation et le suivi peuvent être difficiles. Les problèmes visuels et les troubles de l’équilibre font partie des plaintes fréquemment rencontrées après un TCCL. En outre, ces problèmes peuvent continuer à affecter les personnes ayant eu un TCCL longtemps après la phase aiguë du traumatisme. Cependant, les évaluations cliniques conventionnelles de la vision et de l’équilibre ne permettent pas, la plupart du temps, d’objectiver ces symptômes, surtout lorsqu’ils s’installent durablement. De plus, il n’existe pas, à notre connaissance, d’étude longitudinale ayant étudié les déficits visuels perceptifs, en tant que tels, ni les troubles de l’équilibre secondaires à un TCCL, chez l’adulte. L’objectif de ce projet était donc de déterminer la nature et la durée des effets d’un tel traumatisme sur la perception visuelle et sur la stabilité posturale, en évaluant des adultes TCCL et contrôles sur une période d’un an. Les mêmes sujets, exactement, ont participé aux deux expériences, qui ont été menées les mêmes jours pour chacun des sujets. L’impact du TCCL sur la perception visuelle de réseaux sinusoïdaux définis par des attributs de premier et de second ordre a d’abord été étudié. Quinze adultes diagnostiqués TCCL ont été évalués 15 jours, 3 mois et 12 mois après leur traumatisme. Quinze adultes contrôles appariés ont été évalués à des périodes identiques. Des temps de réaction (TR) de détection de clignotement et de discrimination de direction de mouvement ont été mesurés. Les niveaux de contraste des stimuli de premier et de second ordre ont été ajustés pour qu’ils aient une visibilité comparable, et les moyennes, médianes, écarts-types (ET) et écarts interquartiles (EIQ) des TR correspondant aux bonnes réponses ont été calculés. Le niveau de symptômes a également été évalué pour le comparer aux données de TR. De façon générale, les TR des TCCL étaient plus longs et plus variables (plus grands ET et EIQ) que ceux des contrôles. De plus, les TR des TCCL étaient plus courts pour les stimuli de premier ordre que pour ceux de second ordre, et plus variables pour les stimuli de premier ordre que pour ceux de second ordre, dans la condition de discrimination de mouvement. Ces observations se sont répétées au cours des trois sessions. Le niveau de symptômes des TCCL était supérieur à celui des participants contrôles, et malgré une amélioration, cet écart est resté significatif sur la période d’un an qui a suivi le traumatisme. La seconde expérience, elle, était destinée à évaluer l’impact du TCCL sur le contrôle postural. Pour cela, nous avons mesuré l’amplitude d’oscillation posturale dans l’axe antéropostérieur et l’instabilité posturale (au moyen de la vitesse quadratique moyenne (VQM) des oscillations posturales) en position debout, les pieds joints, sur une surface ferme, dans cinq conditions différentes : les yeux fermés, et dans un tunnel virtuel tridimensionnel soit statique, soit oscillant de façon sinusoïdale dans la direction antéropostérieure à trois vitesses différentes. Des mesures d’équilibre dérivées de tests cliniques, le Bruininks-Oseretsky Test of Motor Proficiency 2nd edition (BOT-2) et le Balance Error Scoring System (BESS) ont également été utilisées. Les participants diagnostiqués TCCL présentaient une plus grande instabilité posturale (une plus grande VQM des oscillations posturales) que les participants contrôles 2 semaines et 3 mois après le traumatisme, toutes conditions confondues. Ces troubles de l’équilibre secondaires au TCCL n’étaient plus présents un an après le traumatisme. Ces résultats suggèrent également que les déficits affectant les processus d’intégration visuelle mis en évidence dans la première expérience ont pu contribuer aux troubles de l’équilibre secondaires au TCCL. L’amplitude d’oscillation posturale dans l’axe antéropostérieur de même que les mesures dérivées des tests cliniques d’évaluation de l’équilibre (BOT-2 et BESS) ne se sont pas révélées être des mesures sensibles pour quantifier le déficit postural chez les sujets TCCL. L’association des mesures de TR à la perception des propriétés spécifiques des stimuli s’est révélée être à la fois une méthode de mesure particulièrement sensible aux anomalies visuomotrices secondaires à un TCCL, et un outil précis d’investigation des mécanismes sous-jacents à ces anomalies qui surviennent lorsque le cerveau est exposé à un traumatisme léger. De la même façon, les mesures d’instabilité posturale se sont révélées suffisamment sensibles pour permettre de mesurer les troubles de l’équilibre secondaires à un TCCL. Ainsi, le développement de tests de dépistage basés sur ces résultats et destinés à l’évaluation du TCCL dès ses premières étapes apparaît particulièrement intéressant. Il semble également primordial d’examiner les relations entre de tels déficits et la réalisation d’activités de la vie quotidienne, telles que les activités scolaires, professionnelles ou sportives, pour déterminer les impacts fonctionnels que peuvent avoir ces troubles des fonctions visuomotrice et du contrôle de l’équilibre.

Is there a relation between crossbite and/or an open bite, static postural behaviour, and the incidence of non-traumatic Injuries in young athletes?

Poster presented at the First international Congress of CiiEM “From Basic Sciences to Clinical Research”, 27-28 November 2015, Egas Moniz, Caparica, Portugal.

Description of the reflex zenith tube of the Royal Observatory, Greenwich.

Forming Appendix I. to the Volume of Greenwich observations for the year 1854.

The muscular tension reflex and two of its modifying conditions

"References": p. [22]

Muscular contraction and the reflex control of movement,

"A chronological list of important contributions to the physiology of muscle": p. 53-55.

The Effects of Postural Loading, Sacral Orientation, and Age on Sex Differences in Lumbar Functional Morphology and Health

Thesis (Ph.D.)--University of Washington, 2016-06

External perturbation of the trunk in standing humans differentially activates components of the medial back muscles

During voluntary arm movements, the medial back muscles are differentially active. It is not known whether differential activity also occurs when the trunk is perturbed unpredictably, when the earliest responses are initiated by short-latency spinal mechanisms rather than voluntary commands. To assess this, in unpredictable and self-initiated conditions, a weight was dropped into a bucket that was held by the standing subject (n = 7). EMG activity was recorded from the deep (Deep MF), superficial (Sup MF) and lateral (Lat MF) lumbar multifidus, the thoracic erector spinae (ES) and the biceps brachii. With unpredictable perturbations, EMG activity was first noted in the biceps brachii, then the thoracic ES, followed synchronously in the components of the multifidus. During self-initiated perturbations, background EMG in the Deep MF increased two- to threefold, and the latency of the loading response decreased in six out of the seven subjects. In Sup MF and Lat MF, this increase in background EMG was not observed, and the latency of the loading response was increased. Short-latency reflex mechanisms do not cause differential action of the medial back muscles when the trunk is loaded. However, during voluntary tasks the central nervous system exerts a 'tuned response', which involves discrete activity in the deep and superficial components of the medial lumbar muscles in a way that varies according to the biomechanical action of the muscle component.

Experimental muscle pain changes feedforward postural responses of the trunk muscles

Many studies have identified changes in trunk muscle recruitment in clinical low back pain (LBP). However, due to the heterogeneity of the LBP population these changes have been variable and it has been impossible to identify a cause-effect relationship. Several studies have identified a consistent change in the feed-forward postural response of transversus abdominis (TrA), the deepest abdominal muscle, in association with arm movements in chronic LBP. This study aimed to determine whether the feedforward recruitment of the trunk muscles in a postural task could be altered by acute experimentally induced LBP. Electromyographic (EMG) recordings of the abdominal and paraspinal muscles were made during arm movements in a control trial, following the injection of isotonic (non-painful) and hypertonic (painful) saline into the longissimus muscle at L4, and during a 1-h follow-up. Movements included rapid arm flexion in response to a light and repetitive arm flexion-extension. Temporal and spatial EMG parameters were measured. The onset and amplitude of EMG of most muscles was changed in a variable manner during the period of experimentally induced pain. However, across movement trials and subjects the activation of TrA was consistently reduced in amplitude or delayed. Analyses in the time and frequency domain were used to confirm these findings. The results suggest that acute experimentally induced pain may affect feedforward postural activity of the trunk muscles. Although the response was variable, pain produced differential changes in the motor control of the trunk muscles, with consistent impairment of TrA activity.

The independent effects of attention and lead stimulus properties on the acoustic blink reflex

The effects of attention to a lead stimulus and of its sensory properties on modulation of the acoustic blink reflex were investigated. Participants performed a reaction time task cued by an acoustic or a visual lead stimulus. In Experiment 1, half the participants were presented with sustained lead stimuli. For the remainder, the lead stimulus was discrete and consisted of two brief presentations that marked the onset and offset of a stimulus-free interval. In Experiment 2, sustained lead stimuli were presented at a low or high intensity. The attentional demands of the task enhanced blink latency and magnitude modulation during acoustic and visual lead stimuli, with blink modulation being largest at a late point during the lead stimulus. Independent of the attentional effects, blink latency and magnitude modulation were larger during sustained than during discrete acoustic lead stimuli, whereas there was no difference for visual lead stimuli. Increases in the intensity of the lead stimulus enhanced blink modulation regardless of lead stimulus modality. Attention to a lead stimulus and the properties of the lead stimulus appear to have independent effects on blink reflex modulation.

Spatio-temporal evaluation of neck muscle activation during postural perturbations in healthy subjects

The purpose of this study was to examine the spatio-temporal activation of the sternocleidomastoid (SCM) and cervical extensor (CE) muscles with respect to the deltoid muscle onset during rapid voluntary upper limb movement in healthy volunteers. The repeatability and reliability of the spatio-temporal aspects of the myoelectric signals were also examined. Ten subjects performed bilateral and unilateral rapid upper limb flexion, abduction and extension in response to a visual stimulus. EMG onsets and normalised root mean square (nRMS) values were calculated for the SCM and CE muscles. Subjects attended three testing sessions over non-consecutive days allowing the repeatability and reliability of these measures to be assessed. The SCM and CE muscles demonstrated feed-forward activation (activation within 50 ms of deltoid onset) during rapid arm movements in all directions. The sequence and magnitude of neck muscle activation displayed directional specificity, however, the neck flexor and extensor muscles displayed co-activation during all perturbations. EMG onsets demonstrated high repeatability in terms of repeated measure precision (nSEM in the range 1.9-5.7%). This was less evident for the repeatability of nRMS values. The results of this study provide a greater understanding of cervical neuromotor control strategies. During bilateral and unilateral upper limb perturbations, the SCM and CE muscles demonstrate feed-forward co-activation. It seems apparent that feed-forward activation of neck muscles is a mechanism necessary to achieve stability for the visual and vestibular systems, whilst ensuring stabilisation and protection of the cervical spine. (C) 2004 Elsevier Ltd. All rights reserved.

Pain differs from non-painful attention-demanding or stressful tasks in its effect on postural control patterns of trunk muscles

Pain changes postural activation of the trunk muscles. The cause of these changes is not known but one possibility relates to the information processing requirements and the stressful nature of pain. This study investigated this possibility by evaluating electromyographic activity (EMG) of the deep and superficial trunk muscles associated with voluntary rapid arm movement. Data were collected from control trials, trials during low back pain (LBP) elicited by injection of hypertonic saline into the back muscles, trials during a non-painful attention-demanding task, and during the same task that was also stressful. Pain did not change the reaction time (RT) of the movement, had variable effects on RT of the superficial trunk muscles, but consistently increased RT of the deepest abdominal muscle. The effect of the attention-demanding task was opposite: increased RT of the movement and the superficial trunk muscles but no effect on RT of the deep trunk muscles. Thus, activation of the deep trunk muscles occurred earlier relative to the movement. When the attention-demanding task was made stressful, the RT of the movement and superficial trunk muscles was unchanged but the RT of the deep trunk muscles was increased. Thus, the temporal relationship between deep trunk muscle activation and arm movement was restored. This means that although postural activation of the deep trunk muscles is not affected when central nervous system resources are limited, it is delayed when the individual is also under stress. However, a non-painful attention-demanding task does not replicate the effect of pain on postural control of the trunk muscles even when the task is stressful.

Postural and respiratory activation of the trunk muscles changes with mode and speed of locomotion

Despite the importance of the deep intrinsic spinal muscles for trunk control, few studies have investigated their activity during human locomotion or how this may change with speed and mode of locomotion. Furthermore, it has not been determined whether the postural and respiratory functions, of which these muscles take part, can be coordinated when locomotor demands are increased. EMG recordings of abdominal and paraspinal muscles were made in seven healthy subjects using fine-wire and surface electrodes. Measurements were also made of respiration and gait parameters. Recordings were made for 10s as subjects walked on a treadmill at 1 and 2 ms(-1) and ran at 2, 3, 4 and 5 ms(-1). Unlike the superficial muscles, transversus abdominis was active tonically throughout the gait cycle with all tasks, except running at speeds of 3 ms(-1) and greater. All other muscles were recruited in a phasic manner. The relative duration of these bursts of activity was influenced by speed and/or mode of locomotion. Activity of all abdominal muscles, except rectus abdominis (RA), was modulated both for respiration and locomotor-related functions but this activity was affected by the speed and mode of locomotion. This study provides evidence that the deep abdominal muscles are controlled independently of the other trunk muscles. Furthermore, the pattern of recruitment of the trunk muscles and their respiratory and postural coordination is dependent on the speed and mode of locomotion. (C) 2003 Published by Elsevier B.V.