Influence of spinal cord lesion level and severity on H‐reflex excitability and recovery curve

Abstract

The changes in spinal reflexes as measured by the H-reflex and its recovery curve after SCI depend on the severity, but not on the level of the lesion.

Common neural structures activated by epidural and transcutaneous lumbar spinal cord stimulation: Elicitation of posterior root-muscle reflexes

“…Table 1 ), whereas nine of the patients in the transcutaneous SCS group had motor-incomplete lesions (4 AIS C, 5 AIS D). Previous studies of the soleus H reflex revealed significantly smaller M max amplitudes in individuals with complete compared to incomplete SCI [ 87 ]. As there was no correlation of the H max -to-M max ratio with the severity of SCI [ 87 , 88 ], also the sizes of H max must have been smaller in case of motor-complete lesions.…”

“…Previous studies of the soleus H reflex revealed significantly smaller M max amplitudes in individuals with complete compared to incomplete SCI [ 87 ]. As there was no correlation of the H max -to-M max ratio with the severity of SCI [ 87 , 88 ], also the sizes of H max must have been smaller in case of motor-complete lesions. Along this line, earlier studies showed greater soleus stretch reflexes [ 88 ] as well as responses to Achilles’ tendon taps [ 89 ] in motor-incomplete vs. complete SCI that were attributed to differences in long-tract sparing and secondary mechanical adaptations in the muscle and tendon complex associated with different SCI severities [ 87 – 89 ].…”

“…As there was no correlation of the H max -to-M max ratio with the severity of SCI [ 87 , 88 ], also the sizes of H max must have been smaller in case of motor-complete lesions. Along this line, earlier studies showed greater soleus stretch reflexes [ 88 ] as well as responses to Achilles’ tendon taps [ 89 ] in motor-incomplete vs. complete SCI that were attributed to differences in long-tract sparing and secondary mechanical adaptations in the muscle and tendon complex associated with different SCI severities [ 87 – 89 ]. The differences in lesion severity between the transcutaneous and the epidural SCS group may have also contributed to the differences in post-activation depression found in BF [ 87 ].…”

Effects of repetitive transcranial magnetic stimulation and trans-spinal direct current stimulation associated with treadmill exercise in spinal cord and cortical excitability of healthy subjects: A triple-blind, randomized and sham-controlled study

“…Homosynaptic depression was assessed by H-reflex recovery curve [ 40 – 42 ]. We plotted the Hr recovery curve by delivering pairs of stimuli following the same setting described above with equal Hr (max) intensity and duration.…”

Striatal cholinergic interneuron numbers are increased in a rodent model of dystonic cerebral palsy

“…The Hoffman reflex (H-reflex), the electrophysiological equivalent of the spinal stretch reflex, was measured as an analogue of spasticity. Spasticity is associated with hyperreflexia and spasticity severity is known to correlate with higher H-reflex amplitudes particularly with high frequency stimulation (Chen et al, 2001;Garrison et al, 2011;Hoving et al, 2006;Kumru et al, 2015;Pizzi et al, 2005;Ryu et al, 2017;Tekgül et al, 2013;Yates et al, 2008). H-reflexes were elicited in rats lightly sedated with isoflurane (0.5 to 1% v/v in oxygen) such that vibrissae and whisking reflexes were absent.…”