Separate quantification of reflex and nonreflex components of spastic hypertonia in chronic hemiparesis.
OBJECTIVE
To isolate and quantify reflex and nonreflex components of the spastic ankle plantarflexors in hemiplegia poststroke and to correlate them with clinical measures of spasticity, which may involve hyperactive stretch reflex and/or increased joint stiffness.


METHODS
To investigate reflex and nonreflex properties associated with spasticity in a case-control manner.


METHODS
Research laboratory in a rehabilitation hospital.


METHODS
Hemiplegic patients (n=17) and the same number of healthy subjects.


METHODS
Not applicable.


METHODS
Tendon reflexes of spastic muscles were evaluated under an isometric condition, which essentially eliminated passive viscoelastic contributions associated with limb movement. Nonreflex components of spasticity were evaluated by moving the ankle joint slowly, which minimized reflex actions. The reflex and nonreflex measures were investigated and correlated with each other and with clinical measures.


RESULTS
Compared with healthy subjects, patients with stroke showed a lower reflex threshold, higher electromyographic gains, and torque reflex gains, indicating hyperactive reflexes. For nonreflex properties, ankles of stroke patients showed higher stiffness, reduced range of motion (ROM), and larger resistant torque at comparable positions, reflecting peripheral soft-tissue changes at the ankle of the chronic stroke patients. Furthermore, the clinical reflex score correlated with all of the quantitative reflex measures but not with the nonreflex measures, whereas the dorsiflexion ROM showed a significant correlation with a nonreflex measure. The Modified Ashworth Scale was correlated with all of the reflex measures and 1 of the nonreflex measures.


CONCLUSIONS
Comprehensive and convenient evaluation of spasticity should be performed quantitatively with the separate measures of reflex and nonreflex components, especially in chronic conditions. With proper simplifications, the current method of separate quantification can potentially be used for convenient clinical evaluations of spasticity.
Chung
Sun G
SG
Rehabilitation Institute of Chicago, Chicago, IL, USA.
van Rey
Elton
E
Bai
Zhiqiang
Z
Rymer
W Zev
WZ
Roth
Elliot J
EJ
Zhang
Li-Qun
LQ
D000125:Achilles Tendon / Q000503:physiopathology; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D000843:Ankle Joint / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005069:Evaluation Studies as Topic; D005260:Female; D006429:Hemiplegia / Q000209:etiology / Q000534:rehabilitation*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009122:Muscle Hypertonia / Q000175:diagnosis* / Q000534:rehabilitation; D009989:Orthotic Devices; D011336:Probability; D016059:Range of Motion, Articular / Q000502:physiology; D012016:Reference Values; D012021:Reflex, Abnormal; D015203:Reproducibility of Results; D018570:Risk Assessment; D020521:Stroke / Q000150:complications / Q000175:diagnosis; D000071939:Stroke Rehabilitation