Antinociceptive Effect of Botulinum Toxin A in Persistent Muscle Pain Rat Model

OBJECTIVE: To investigate the effects of botulinum toxin on the mechanical hyperalgesia, electrophysiology and motor functions in the persistent muscle pain rat model. METHOD: A secondary mechanical hyperalgesia in the bilateral hindpaws of Sprague-Dawley rats was produced by the repeated injections of acidic saline into gastrocnemius. Botulinum toxin A (BTX-A(4): 4 U/kg, BTX-A(7): 7 U/kg) was administrated into same muscle 24 hours after a second injection of saline. The mechanical hyperalgesia was measured with withdrawal threshold to von Frey filament. The grade of muscle paralysis was evaluated with electrophysiology and the locomotor performance using inclined plane board. RESULTS: The mechanical hyperalgesia was significantly decreased from 5 days to 2 weeks in BTX-A(7) group in the injected side. The dose-dependent decreased amplitude of compound muscle action potential and reduced prevalence of endplate noise from the first day of botulinum toxin injection lasted for 4 weeks in both gastrocnemius. The maximum angle maintained at initial position on the inclined plane board did not change. CONCLUSION: Local muscular injection of botulinum toxin A reduced ipsilateral hyperalgesia dose-dependently in persistent muscle pain rat model without motor deficit. The antinociceptive mechanism of botulinum toxin might act at a local or peripheral rather than a systemic or central effect due to ineffectiveness of contralateral hyperalgesia. Clinically, botulinum toxin A might be useful for the treatment of local and referred pain of muscle origins.

Kinetic Characteristics during Initiation of Gait in Stroke Patients

OBJECTIVE: The aim of the present study was to understand biomechanical characteristics during the process of initiation of gait (IOG) from the standing position in hemiplegic patients. METHOD: We recorded the ratio of the vertical forces of both limbs to body weight and the movement of net center of pressure (COP) on two force platforms during the process of initiation of gait (IOG) from standing in 10 normal control and 10 hemiplegic patients and processed these data using ELITE DMA acquisition program. All data were collected with uninvolved limb and involved limb and compared each other by independent samples t-test. RESULTS: 1) In 10 hemiplegic patients, nine patients began taking a step with an uninvolved limb in the first, followed by an involved limb. 2) The period of IOG of the swing limb was 0.80 sec when patients walked with an uninvolved side and those of the stance limb was 1.60 sec with involved side. When the control group walked, the period of IOG of the swing limb was 0.70 sec and those of stance limb was 1.50 sec. The period of IOG of the swing limb in uninvolved side and those of the stance limb in involved side showed significant longer than control group. 3) The latency of IOG of swing and stance limb was significantly more prolonged than control groups. 4) Anteroposterior (AP) and mediolateral (ML) distance of net COP from release to unloading with uninvolved limb showed significant longer than control groups. 5) The velocity of net COP displacement from start to release with involved limb was significantly slower than control groups. CONCLUSION: This pattern of IOG could be used as one of the tools to evaluate postural control during gait training in the hemiplegic patients with gait disabilities, and it can be used as a basis for specific therapeutic intervention, and it allows evaluation of the effectiveness of treatment.

The Quantitative Measurement of Spasticity Using Change of Muscle Length during Pendulum Test

OBJECTIVE: The aim of this study was to develop objective evaluation method of spasticity which reflects the characteristics of lengthening velocity-dependent stretch reflex of spasticity. METHOD: Kinematic analysis for knee angle and rectus femoris muscle lengthening parameters, and dynamic EMG were performed simultaneously during pendular movement of spastic lower leg for thirty two patients with spasticity and ten normal control subjects. Angular parameters consist of angular relaxation index (ARI), maximal angular velocity (MAV), angular threshold (AT) and angular velocity threshold (AVT). And lengthening parameters consist of lengthening relaxation index (LRI), maximal lengthening velocity (MLV), lengthening threshold (LT) and lengthening velocity threshold (LVT). RESULTS: 1) ARI, MAV, AT, and AVT according to Modified Ashworth scale (MAS) were 1.32+/-0.11, 303.84+/-45.11 deg/sec, 44.19+/-13.81 deg, 262.15+/-33.54 deg/sec in MAS I, 1.16+/-0.16, 279.92+/-42.94 deg/sec, 30.33+/-6.02 deg, 247.65+/-35.92 deg/sec in MAS II, and 0.95+/-0.14, 241.31+/-19.98 deg/sec, 20.55+/-2.68 deg, 209.11+/-48.11 deg/sec in MAS III (P<0.05). 2) LRI, MLV, LT, and LVT according to MAS were 1.27+/-0.11, 0.58+/-0.07, 1.164+/-0.14, 0.53+/-0.05 in MAS I, 1.12+/-0.09, 0.53+/-0.05, 1.150+/-0.08, 0.42+/-0.04 in MAS II, and 0.99+/-0.10, 0.44+/-0.01, 1.137+/-0.15, 0.36+/-0.02 in MAS III (P<0.05). 3) There were significant correlation between various pendulum test parameters and MAS. CONCLUSION: Muscle lengthening parameters as well as knee angular parameters were sensitive parameters reflecting the degree of spasticity. LVT is the most sensitive parameter among all parameters (p<0.01).

Comparative Analysis of Developmental Assessment, Evoked Potentials, Electroencephalography, and Brain MRI in Children with Cerebral Palsy

OBJECTIVE: The present study was undertaken to determine the value of developmental assessment, multimodality evoked potentials, brain magnetic resonance image (MRI) and electroencephalography (EEG) and to identify correlations between each evaluation. METHOD: Developmental assessments such as Bayley scales of infant development and Vineland social maturity scale, brain MRI, EEG and evoked potentials findings were evaluated in 45 children with spastic cerebral palsy to assess the developmental level and abnormalities of the anatomical structure of the brain and to elucidate the relationship between the test methods. RESULTS: 1) Mean mental developmental index (MDI) and psychomotor developmental index (PDI) were 69.6 and 68.6, respectively and mean Vineland social maturity quotient (SQ) was 76.1 and there was a significant correlation between the MDI, PDI, and SQ in cerebral palsied children. 2) Abnormal findings of brain MRI and EEG were found in 73.3% and 44.4% of the cases, respectively. 3) There was significant correlation between findings of brain MRI, auditory evoked potentials, visual evoked potentials, median somatosensory evoked potentials and social quotient. CONCLUSION: Developmental assessment, multimodality evoked potentials, EEG, and brain MRI would be a useful method to evaluate the maturity of brain and estimate the level of development.

Pain and Psychometric Characteristics Related to Disability Evaluation in Patients with Chronic Low Back Pain

OBJECTIVE: To evaluate the effect of compensation or secondary gain on the pain behavior and psychometric characteristics. METHOD: We examined 88 patients who complained of chronic low back pain by the various pain questionnaires, electrodiagnostic study and magnetic resonance imaging (MRI). Total patients were classified into two groups (46 patients who wanted disability evaluation and 42 patients who did not). RESULTS: Mean score of visual analogue scale, total sum of McGill pain questionnaire and pain rating index on sensory, affective and miscellaneous dimensions were significantly higher in patients related to disability compensation than those in patients without compensation. Mean scores of pain disability index and symptom checklist-90-revision were significantly higher on various subclass in patients with compensation. Various pain scales were significantly correlated to each other in both group but the severity of electrodiagnostic study and MRI findings were not related with the degree of pain index score in both group. CONCLUSION: Compensation or secondary gain affect pain behavior and psychometric characteristics in chronic low back patients. So when we evaluate or treat the patients with chronic low back pain, we should consider above results.