Effects of electrically induced muscle contraction on flexion reflex in human spinal cord injury

Knikou, Maria; Conway, B.A.

doi:10.1038/sj.sc.3101772

Cited by 31 publications

(22 citation statements)

References 40 publications

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“…This is in agreement with previous observations in SCI subjects (Shahani and Young 1971;Roby-Brami and Bussel 1987;Knikou and Conway 2005), and in spinal l-dopa-treated cats (Conway et al 1987;Anden et al 1966a). In the present study, the test reflex stimulus intensity was normalized to the threshold of the first evoked TA EMG activity, whether this corresponded to the early or to the late flexion reflex.…”

Section: Observations On the Two Types Of The Flexion Reflexsupporting

confidence: 79%

“…Because of the strong reciprocal expression of this response between excitatory interneuronal pathways (from ipsi-and contralateral FRA) to flexor and extensor motoneurons, Jankowska et al (1967a, b) suggested that this reflex is also involved in spinal stepping, verified by the alternating bursts of flexor and extensor activity following administration of Nialamide (Jankowska et al 1967a). Excitation of FRAs at a non-nociceptive level induces also a late flexion reflex in individuals with a motor complete SCI (Roby-Brami and Bussel 1987;Knikou and Conway 2005), which displays similar characteristics to that observed in the spinal cat after l-dopa Bussel 1990, 1992).…”

Section: Introductionmentioning

confidence: 49%

“…Previous work has shown that the flexion reflex is influenced by limb posture, site of stimulation, electrically-induced muscle contraction, and by actions of descending pathways (Hagbarth 1952;Andersen et al 1999;Baxendale and Ferrell 1981;Schomburg 1990;Baldissera et al 1981;Knikou and Conway 2005). In the acute spinal cat preparation, late flexion reflexes are generated by spinal interneurons that are strongly modulated by signals transmitting hip position (Grillner and Rossignol 1978).…”

Section: Introductionmentioning

confidence: 99%

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Modulation of flexion reflex induced by hip angle changes in human spinal cord injury

2005

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The flexion reflex can be elicited via stimulation of skin, muscle, and high-threshold afferents inducing a generalized flexion of the limb. In spinalized animal models this reflex is quite prominent and is strongly modulated by actions of hip proprioceptors. However, analogous actions on the flexion reflex in spinal cord injured (SCI) humans have not yet been examined. In this study, we investigated the effects of imposed static hip angle changes on the flexion reflex in ten motor incomplete SCI subjects when input from plantar cutaneous mechanoreceptors was also present. Flexion reflexes were elicited by low-intensity stimulation of the sural nerve at the lateral malleolus, and were recorded from the ipsilateral tibialis anterior (TA) muscle. Plantar skin stimulation was delivered through two surface electrodes placed on the metatarsals, and was initiated at different delays ranging from 3 to 90 ms. We found that non-noxious sural nerve stimulation induced two types of flexion reflexes in the TA muscle, an early, and a late response. The first was observed only in three subjects and even in these subjects, it appeared irregularly. In contrast, the second (late) flexion reflex was present uniformly in all ten subjects and was significantly modulated during hip angle changes. Flexion reflexes recorded with hip positioned at different angles were compared to the associated control reflexes recorded with hip flexed at 10°. Hip flexion (30°, 40°) depressed the late flexion reflex, while no significant effects were observed with the hip set in neutral angle (0°). Strong facilitatory effects on the late flexion reflex were observed with the hip extended to 10°. Moreover, the effects of plantar skin stimulation on the flexion reflex were also found to depend on the hip angle. The results suggest that hip proprioceptors and plantar cutaneous mechanoreceptors strongly modulate flexion reflex pathways in chronic human SCI, verifying that this type of sensory afferent feedback interact with spinal interneuronal circuits that have been considered as forerunners of stepping and locomotion. The sensory consequences of this afferent input should be considered in rehabilitation programs aimed to restore movement and sensorimotor function in these patients.

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Section: Observations On the Two Types Of The Flexion Reflexsupporting

confidence: 79%

Section: Introductionmentioning

confidence: 49%

Section: Introductionmentioning

confidence: 99%

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Modulation of flexion reflex induced by hip angle changes in human spinal cord injury

2005

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“…Further, the SRL TA response was depressed during hip flexion at C-T intervals that varied from 30 to 90 ms (Fig. 2B), supporting further the involvement of different interneuronal circuits in the expression of the flexion reflex components (Knikou and Conway, 2005). Similarly, the soleus H-reflex displayed an early followed by a late conditioning effect during hip extension (Fig.…”

Section: Contribution Of Feedback From the Foot Sole And Hip To Spinasupporting

confidence: 55%

“…The stimulus intensity required to induce the initial EMG activity in the TA was identified as the reflex threshold (RT). Reflex responses were categorized as short reflex loop (SRL) responses when their latency was less than 100 ms or long reflex loop (LRL) responses when their latency was beyond 120 ms (Spaich et al, 2004;Knikou and Conway, 2005). During testing, the sural nerve was stimulated at 1.5 times the RT and ranged from 12 to 45 mA (32 ±13.7) across subjects.…”

Section: Stimulation and Recording Protocols Of The Spinal Reflexesmentioning

confidence: 99%

Parallel facilitatory reflex pathways from the foot and hip to flexors and extensors in the injured human spinal cord

Knikou

Kay

Schmit

2007

Experimental Neurology

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Spinal integration of sensory signals associated with hip position, muscle loading, and cutaneous sensation of the foot contributes to movement regulation. The exact interactive effects of these sensory signals under controlled dynamic conditions are unknown. The purpose of the present study was to establish the effects of combined plantar cutaneous afferent excitation and hip movement on the Hoffmann (H) and flexion reflexes in people with a spinal cord injury (SCI). The flexion and Hreflexes were elicited through stimulation of the right sural (at non-nociceptive levels) and posterior tibial nerves respectively. Reflex responses were recorded from the ipsilateral tibialis anterior (TA) (flexion reflex) and soleus (H-reflex) muscles. The plantar cutaneous afferents were stimulated at three times the perceptual threshold (200 Hz, 24-ms pulse train) at conditioning-test intervals that ranged from 3 to 90 ms. Sinusoidal movements were imposed to the right hip joint at 0.2 Hz with subjects supine. Control and conditioned reflexes were recorded as the hip moved in flexion and extension. Leg muscle activity and sagittal-plane joint torques were recorded. We found that excitation of plantar cutaneous afferents facilitated the soleus H-reflex and the long latency flexion reflex during hip extension. In contrast, the short latency flexion reflex was depressed by plantar cutaneous stimulation during hip flexion. Oscillatory joint forces were present during the transition phase of the hip movement from flexion to extension when stimuli were delivered during hip flexion. Hip-mediated input interacts with feedback from the foot sole to facilitate extensor and flexor reflex activity during the extension phase of movement. The interactive effects of these sensory signals may be a feature of impaired gait, but when they are appropriately excited, they may contribute to locomotion recovery in these patients.

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Injuries of the Middle and Lower Cervical Spine

2016

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Effects of electrically induced muscle contraction on flexion reflex in human spinal cord injury

Cited by 31 publications

References 40 publications

Modulation of flexion reflex induced by hip angle changes in human spinal cord injury

Modulation of flexion reflex induced by hip angle changes in human spinal cord injury

Parallel facilitatory reflex pathways from the foot and hip to flexors and extensors in the injured human spinal cord

Injuries of the Middle and Lower Cervical Spine

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