osteopathic-manipulative-treatment-as-useful-adjunctive-tool-for

Osteopathic Manipulative Treatment as a Useful Adjunctive Tool for Pneumonia

Pneumonia, the inflammatory state of lung tissue primarily due to microbial infection, claimed 52,306 lives in the United States in 20071 and resulted in ...

New York Institute of Technology College of Osteopathic Medicine

This work tested the physiological basis underlying the control of a proximo-distal muscle coordination. Using transcranial magnetic stimulation (TMS) of the hand territory within the primary motor cortex (M1), we examined whether the corticospinal excitability of the first dorsal interosseus muscle (FDI, index abductor), engaged in a precision grip, was altered during wrist movements. To this end, 12 seated subjects maintained a pinch between the right index finger and the thumb and FDI motor evoked potentials (MEPs) were elicited under four conditions: (1) during active and (2) passive cyclic wrist flexion/extension, (3) in three positions of static wrist flexion and extension, respectively, and (4) at three levels of isometric force of wrist flexors (FCR) and extensors (ECR) respectively. FDI MEPs were normalized relative to the MEP/EMG linear relationship. They were facilitated during wrist flexion in the active and the passive conditions and this did not depend on FDI background EMG. Interestingly, the occurrence of the most facilitated FDI MEPs was correlated only with the peak of FCR activity. Also, the duration of the post-MEP silent periods normalized to FDI MEP amplitudes was shorter during wrist flexion compared to extension. We discussed the extent to which the dynamic influence of wrist flexion on FDI corticospinal excitability reflects the existence of a proximo-distal synergy between wrist flexion and precision grip and whether this synergy relies on the phase-dependent recruitment of common M1 networks between FCR and FDI muscles and on the salience of proprioceptive afferents from wrist muscles.

Dynamic changes in corticospinal control of precision grip during wrist movements.

This work questioned further the influence of wrist movements on the control of precision grip. Seated subjects wearing a full-arm orthosis with the wrist and hand free were instructed to maintain a thumb/index finger opposition corresponding to 15% of maximal voluntary contraction for the first dorsal interosseus (FDI). Paired-pulse transcranial magnetic stimulation eliciting conditioned MEPs of FDI was used to determine the modulation of short intracortical inhibition (SICI) during cyclic active and passive wrist flexion and extension and during a static condition (no wrist movement, hand in the neutral position). The FDI active motor threshold (AMT) and the conditioning stimulus (0.8 AMT) were assessed in each series of FDI SICI measurements and the test stimulus (TS) was adjusted to match the amplitudes of test FDI MEPs across conditions. An increase of FDI background EMG during active wrist flexion compared to extension in some subjects did not influence FDI SICI as tested at matched EMG levels in the static condition. FDI SICI was reduced during wrist flexion (whether active or passive) compared to wrist extension, the latter being of equivalent FDI SICI as in the static condition. We suggest that wrist flexion and precision grip could be linked in a functional proximo-distal synergy. Indeed, coupling the activity between M1 sites of wrist flexors and FDI muscle via cortico-cortical disinhibition of FDI site may help recruit the interjoint synergy. Also, the salience of afferent information from wrist muscles may contribute to the phase-dependent modulation of SICI in the preactivated FDI muscle.

Dynamic influence of wrist flexion and extension on the intracortical inhibition of the first dorsal interosseus muscle during precision grip.

It is generally considered that hand amputation changes primary motor cortex (M1) stump muscle representations. Transcranial magnetic stimulation (TMS) studies show that the corticospinal excitability of a stump muscle and its homologous muscle on the intact side is not equivalent, and that the resting level of excitability is higher in the stump muscle. Since changes in M1 stump muscle map characteristics (e.g., size and location) are identified by comparing stump and intact muscle maps, such changes might reflect between-side differences in corticospinal excitability rather than a true reorganization of the stump muscle's map. In eight above-elbow amputees we used TMS to map the M1 representation of a stump muscle and its homologous muscle on the intact side during rest and contraction. Importantly, the same relative stimulation intensity was used to construct each map; stimulation was performed at 120% of the motor threshold of each muscle (intact/amputated limb) measured in each condition (rest/active contraction). Resting motor threshold was lower in the stump muscle, but active motor thresholds did not differ. Motor-evoked potential amplitudes increased between the rest and muscle contraction conditions, but this increase was smaller for the stump muscle because its at-rest corticospinal excitability was higher than that of the intact muscle. When the between-side difference in excitability was considered no interhemispheric difference was found for map areas or for their medio-lateral locations. The present results challenge the view that after an upper limb amputation the stump representation moves laterally and occupies a larger M1 territory.

The map is not the territory: motor system reorganization in upper limb amputees.

Patients with chronic pain often show disturbances in their body perception. Understanding the exact role played by pain is however complex, as confounding factors can contribute to the observed deficits in these clinical populations. To address this question, acute experimental pain was used to test the effect of lateralized pain on body perception in healthy subjects. Subjects were asked to indicate the position of their body midline (subjective body midline, SBM) by stopping a moving luminescent dot projected on a screen placed in front of them, in a completely dark environment. The effect of other non-painful sensorimotor manipulations was also tested to assess the potential unspecific attentional effects of stimulating one side of the body. SBM judgment was made in 17 volunteers under control and three experimental conditions: (1) painful (heat) stimulation; (2) non-painful vibrotactile stimulation; and (3) muscle contraction. The effects of the stimulated side and the type of trial (control vs. experimental condition), were tested separately for each condition with a 2 × 2 repeated measures ANOVA. The analyses revealed a significant interaction in both pain (p = 0.05) and vibration conditions (p = 0.04). Post hoc tests showed opposite effects of pain and vibration. Pain applied on the right arm deviated the SBM toward the right (stimulated) side (p = 0.03) while vibration applied on the left arm deviated the SBM toward the right (not stimulated) side (p = 0.01). These opposite patterns suggest that the shift in SBM is likely to be specifically linked to the stimulation modality. It is concluded that acute experimental pain can induce an SBM shift toward the stimulated side, which might be functionally beneficial to protect the painful area of the body. Interestingly, it appears to be easier to bias SBM toward the right side, regardless of the modality and of the stimulated side.

Article	Year
Dynamic changes in corticospinal control of precision grip during wrist movements. Brain research\| PubMed ID: 17632089	2007
Dynamic influence of wrist flexion and extension on the intracortical inhibition of the first dorsal interosseus muscle during precision grip. Brain research\| PubMed ID: 18206858	2008
The map is not the territory: motor system reorganization in upper limb amputees. Human brain mapping\| PubMed ID: 21391244	2011
Effect of painful and non-painful sensorimotor manipulations on subjective body midline. Frontiers in human neuroscience\| PubMed ID: 23504448	2013

Martin Gagne

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