Position-dependent, hyperexcitable patellar reflex dynamics in chronic stroke.
OBJECTIVE
To quantify tendon tap response (TTR) properties and their position dependence using multiple neuromechanical parameters, and to analyze correlations among neuromechanical and clinical measures.


METHODS
Hyperexcitable dynamics of TTR were investigated in a case-control manner. An instrumented hammer was used to induce the patellar deep tendon reflex (DTR), with reflex-mediated electromyography and torque responses measured across a range of knee flexion.


METHODS
Research laboratory in a rehabilitation hospital.


METHODS
Chronic hemiplegic stroke survivors (n=9) and healthy subjects (n=13).


METHODS
Not applicable.


METHODS
Neuromechanical measures (system gain, contraction rate, half-relaxation rate, reflex loop delay, peak reflex torque, peak reflex electromyography, and reflex threshold in tapping force) were measured to characterize neuromuscular properties of patellar TTR. Clinical measurements were taken using the DTR scale and the Modified Ashworth Scale.


RESULTS
The system gain, contraction rate, half-relaxation rate, and peak reflex-mediated torque in the stroke group were generally higher, whereas the reflex threshold in the stroke group was significantly lower than their counterparts in the control group across 45° to 90° of knee flexion (P<.05). The 4 parameters were significantly higher at 60° and 75° of flexion than at 15°, 30°, 45°, and 90°, and their correlations with the 2 clinical scales at 60°, 75°, and 90° of flexion were also significantly higher than those at 15°, 30°, and 45° (P<.05).


CONCLUSIONS
The results showed hyperexcitability of TTR in stroke, quantified using a number of neuromechanical measures. Those measures peak around 60° to 75° of knee flexion and were correlated with clinical scales.
Rehabilitation Institute of Chicago, Chicago, IL 60611, USA.
Chung-Yong
CY
Yang
Xin
X
Guo
Yupeng
Y
Ren
Sang Hoon
SH
Kang
Li-Qun
LQ
Zhang
D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D004576:Electromyography; D005260:Female; D006429:Hemiplegia / Q000503:physiopathology; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D017847:Patellar Ligament / Q000503:physiopathology*; D016059:Range of Motion, Articular / Q000502:physiology*; D012026:Reflex, Stretch / Q000502:physiology*; D020521:Stroke / Q000503:physiopathology*; D019415:Torque