Reflexes From the Superficial Peroneal Nerve During Walking in Stroke Subjects

Abstract

The function of ipsilateral cutaneous reflexes was studied with short trains of stimuli presented pseudorandomly to the superficial peroneal nerve (SP; innervates the top of the foot) during treadmill walking in neurologically intact (NI) subjects and subjects who had had a stroke. Ankle and knee joint angles together with electromyograms (EMG) of tibialis anterior (TA), soleus (SOL), medial gastrocnemius (MG), vastus lateralis (VL), and biceps femoris (BF) muscles were recorded. Net reflex EMG and kinematic responses to stimulation were quantified in each of the 16 parts of the step cycle and responses compared between the stroke and NI subjects. Stimulation strongly suppressed extensor muscles throughout stance in the stroke subjects. TA muscle showed a significant suppression during swing phase that was correlated with reduced ankle dorsiflexion in both stroke and NI subjects. BF reflexes were facilitatory during parts of swing and VL reflexes were suppressive throughout stance in the stroke subjects. There was a significant correlation between BF facilitation and knee flexion during swing, which was stronger in NI subjects. We conclude that only part of the stumble correction to foot dorsum electrical stimulation observed in NI subjects is maintained after stroke, and that new, suppressive responses are seen.

Involvement of the corticospinal tract in the control of human gait

“…This makes it likely that a transcortical reflex pathway is responsible for the cutaneous reflex. Further evidence in support of this notion comes from the observation that the cutaneous reflex is absent or small during walking in stroke patients (Zehr et al, 1998). Similar observations have also been reported for stretch reflexes mediated by muscle spindle afferents Petersen et al, 1998).…”

Neuromechanical Interlimb Interactions and Rehabilitation of Walking after Stroke

“…Interlimb cutaneous reflex pathways from the LA hand (SR n.) and foot (superficial peroneal n.) remain viable and modulated during walking after stroke [21], a result complimentary to observations within the MA leg [22]. Interestingly, there is a potential enhancement in transmission from LA arm to MA leg as compared to control participants.…”

Gait acts as a gate for reflexes from the foot

“…Vol. 82, 2004 (Zehr et al 1997(Zehr et al , 1998Haridas and Zehr 2003;Duysens et al 1992). PF, plantarflexion, DF, dorsiflexion.…”

“…Several studies with patients with defective cortico-spinal pathways have confirmed this. In stroke patients, Zehr et al (1998) observed that P2 responses were small or absent during walking. Patients with hereditary spastic paraparesis (HSP) have a lesion in the corticospinal tract, and they also show decreased P2 reflexes .…”

“…However, in that case one would expect that there would only be a block of facilitatory input to TA and one would not observe suppression. The suppressive response leads to a plantar flexion of the ankle (Duysens et al 1992;Zehr et al 1997Zehr et al , 1998Van Wezel et al 1997), which could lead to a faster contact of the whole foot with the ground. Hence, this explanation gives a more positive role to the observed suppression, namely, to enhanced limb loading (increased foot contact).…”