CORRELATION OF CLINICAL FINDINGS WITH THE MECHANICAL AND NEURAL PROPERTIES OF MUSCLE SPASTICITY. Cheng-Ya Huang*1; Chun-Hou Wang3,4; Ing-Shiou Hwang1,2 1. Institute of Allied Health Sciences, College of Medicine, National Cheng Kung University, 701, Tainan, Taiwan; 2. School of Physical Therapy, College of Medicine, National Cheng Kung University, 701, Tainan, Taiwan; 3. School of Physical Therapy, College of Medical Technology, Chung Shan Medical University, 402, Taichung, Taiwan; 4. Department of Physical Therapy, Chung Shan Medical University Rehabilitation Hospital, 406, Taichung, Taiwan PURPOSE: With modified H reflex and mechanomyography (MMG), the objectives of this study were 1) to measure the neural and mechanical aspects of spasticity, and their relationship with the severity of hypertonus and functional impairments for affected individuals. BACKGROUNDS/SIGNIFICANCE: Muscle spasticity involves with different degrees of structural changes in tissue compliance and motoneuronal excitability that have yet been satisfactorily characterized with convenient approach for ease of spasticity control in clinical setting. SUBJECTS: Thirty-four patients with SCI (n=15), unilateral stroke (n=19), and normal control subjects (n=23) were recruited. Inclusion criteria for patient subjects were: (1) clinical signs of spasticity in the lower extremity; (2) the ankle could be maintained in the neutral position; (3) no neuropathy of peripheral nerve system; (4) onset more than 3 months. METHODS AND MATERIALS: Soleus H reflex and maximal M response (Mmax) were measured with electromyography and MMG. The motoneuronal excitability was represented with the adjusted ratio of the H reflex to the Mmax (H/Mmax) and the ratio of the paired H reflexes (H2/H1). Muscle mechanical properties were characterized by the amplitude and median frequency (MDF) of maximal M response recorded with MMG (MMGMmax). Clinical scales including the MAS, Barthel index (BI), Fugl-Meyer motor-assessment scale (FM) were applied for functional evaluation. ANALYSES: The difference in H/Mmax, Mmax, H2/H1, amplitude of MMGMmax and median frequency (MDF) of MMGMmax between the different groups was determined by using Student t test. Spearman rho was used to examine the correlation coefficients among all H reflex related parameters and various clinical assessments. Multiple logistic regression analysis with MAS was used to account for the variance of MAS and H reflex related parameters that were significantly related to the MAS. RESULTS: Patients featuring spastic hypertonia consistently exhibited a larger H/Mmax, H2/H1 and amplitude of MMGMmax than those of healthy controls (p < 0.05). The MAS rating correlated significantly with H/Mmax and amplitude of MMGMmax that accounted jointly for 55.7% of the variance in MAS (p < 0.001). The BI and FM scores related inversely with the amplitude of MMGMmax (p < 0.05). CONCLUSIONS: Spastic hypertonia involved with an atypical increase in motoneuronal excitability and muscle mechanical properties. Both features appeared to be related to the MAS, whilst motor performance was hampered only by spasticity-related changes in muscle mechanical properties. FUNDING SOURCE: none KEYWORDS: spasticity, H reflex, mechanomyography, hemiplegics, spinal-cord injury Copyright 2009 by the American Physical Therapy Association. Requests for reprints should be directed to the corresponding author of the article. Educators, students, and other academic customers may receive permission to reprint copyrighted material from Physical Therapy (ISSN 1538-6724) by contacting the Copyright Clearance Center Inc, 222 Rosewood Dr, Danvers, MA 01923. Other types of customers who want permission to reprint should contact the APTA Editorial Office, Attn: Physical Therapy.