Radiographic Evaluation of Foot Deformities in Children with Cerebral Palsy

OBJECTIVE: To evaluate whether 7 radiographic angles make a useful method for analysing foot deformities in children with cerebral palsy, and to assess with changes in angles after 2 years with orthoses or operations. METHOD: The talocalcaneal, talus-first metatarsal, and calcaneus-fifth metatarsal angles on the AP radiographs and the talocalcaneal, tibiotalar, talus-first metatarsal, and talohorizontal angles on the lateral radiographs were measured in 183 cerebral palsied. Seven angles were analyzed according to the clinical types, spasticity, ambulation, and age. One hundred three feet were followed up for 2 years with application of orthoses or operations. RESULTS: The frequencies of higher range in AP talocalcaneal angle were 24.4% in spastic diplegia. The increased frequencies for abnormal range increased as the grade of spasticity. Non-ambulator group had many frequencies of lower range in AP talocalcaneal angle. The age of 8~9 years showed high peak in the frequency of abnormal range. After 2 years, the frequencies of normal range were increased in groups with orthoses or operations. CONCLUSION: The radiographic angles were a useful method for observing feet of the children with cerebral palsy. If the appropriate interventions for feet were applied, the normal frequencies of radiographic angles were increased after 2 years.

Usefulness of Current Withdrawal Threshold on Evaluation of the Neuropathic Pain in Animal Model

OBJECTIVE: To evaluate usefulness of the current withdrawal threshold (CWT) on evaluation of the neuropathic pain in animal model. METHOD: Surgical neuropathy was induced in 40 Sprague-Dawley rats. Fourteen days after the surgery, neuropathic rats were evaluated by von Frey hair. The CWT was determined by various stimulus intensities which induce the tail-withdrawal response or vocalization of rats. The experimental group was compared with the control group by CWT. Then the experimental group was subdevided to two groups. The experimental group 1 was injected with beta-methasone 0.1 mg/kg, intra-peritoneally and experimental group 2 was injected with normal saline with the same amount as steroid. The CWT of two experimental subgroups were measured before and 30 minutes after injections. RESULTS: The experimental group showed significant decrease of the CWT compared with the control group after the neuropathic pain was induced. The CWT of experimental group 1 was increased after steroid administration (p<0.01). CONCLUSION: This preliminary study suggests that the measurement of CWT would be an useful tool to study the neuropathic pain in experimental animal model.

Effects of Clonidine and Yohimbine on Neuropathic Pain in a Rat Model

OBJECTIVE: In a rat model of peripheral neuropathy, to determine whether neuropathic pain is related to the alpha-2 adrenergic receptor. METHOD: The neuropathic pain was produced by unilateral transection of the superior caudal trunk between the S3 and S4 spinal nerves. These animals showed the behavioral signs of neuropathic pain in the tail. Two weeks after the neuropathic surgery, tail withdrawal responses to the mechanical stimuli with von Frey hair (2.0 g) were examined 1, 2 and 24 hrs following the administration of clonidine, alpha-2 receptor agonist. One week after the clonidine test, the same behavioral test was done after the administration of clonidine along with yohimbine, alpha-2 receptor antagonist. RESULTS: Clonidine significantly reduced the frequency of tail response and yohimbine reversed the clonidine-induced anti-allodynic effect. CONCLUSION: These results suggest that neuropathic pain is related to the sympathetic nervous system via alpha-2 adrenergic receptor.

Auditory Brainstem Evoked Potentials in Preterm Infants

OBJECTIVE: To investigate the change of peak latency, interpeak latency and amplitude of auditory brainstem evoked potentials (AEPs) in normal preterm infants in accordance with the age, and to find out the correlation between reproducibility of AEPs and high risk of premature infants. METHOD: AEP studies were performed on 266 premature infants (male 143, female 123) within a month of the birth. Acquired potentials were grouped by the reproducibility of waveforms, and latency, interpeak latency and amplitude were measured in each group of potentials to interpret age appropriate changes of AEPs. RESULTS: 1) Peak latency of peak I, III and V were shortened in accordance with the age, especially latency of peak V was significantly decreased from 7.42 msec to 6.84 msec. 2) There was no significant change in interpeak latency or amplitude of AEPs according to the postmenstrual age. 3) Reproducibility of AEPs was worse in premature infants with history of asphyxia. CONCLUSION: Considering the results, the latency of peak V can be used as one of the useful parameter to investigate and follow up the premature infants. Significant negative correlation between low grade reproducibility and history of neonatal asphyxia was found.

Analysis of Increased Myotatic Reflex in Children with Spastic Cerebral Palsy

OBJECTIVE: The purpose of this study was to analyse the myotatic reflex characteristics of children with spastic cerebral palsy compared with normal infants and children. METHOD: Thirty four children with spastic cerebral palsy and 42 normal children were examined. The tendon taps were applied to the patellar and Achilles' tendons and shin using an electric reflex hammer. Compound muscle action potentials (CMAPs) were recorded from hamstring (HAM), rectus femoris (RF), tibialis anterior (TA), and gastrocnemias (GCL) by surface electrodes. The response ratios of HAMs/RF and TA/GCL were determined from CMAP amplitude. RESULTS: The mean HAM/RF ratios after patellar taps were 0.32+/- 0.33, 0.37 +/-0.33 and 0.32+/- 0.19 in children with cerebral palsy, normal infants, and children over 1 year of age, respectively. The mean TA/GCL ratios following Achilles tap were 0.40 +/- 0.30, 0.93+/- 0.11, and 0.25+/- 0.14 in children with cerebral palsy, normal infants, and children over 1 year of age, respectively. All the spastic cerebral palsy children showed muscle responses in RF, HAM, TA and GCL after shin tap, but normal children did not. CONCLUSION: The results reflect that the reflex responses are exaggerated in children with spastic cerebral palsy, and it can be used in the early diagnosis of cerebral palsy.

Predictive Value of Multi-Sensory Evoked Potentials on Motor Development of Neonates

OBJECTIVE: This study was performed to investigate the prognostic value of multi-sensory evoked potentials (MSEPs) in neonatal period for the early diagnosis of delayed motor development, especially cerebral palsy. METHOD: The MSEPs studies composed of auditory brainstem evoked potentials (AEPs), visual evoked potentials (VEPs) and somatosensory evoked potentials were taken on 237 neonates, 136 boys and 101 girls, using Viking IV machine. Follow up MSEPs were repeated in every 4 or more weeks for those who showed abnormal responses in any of the MSEPs. Each neonate was also evaluated for motor development as an outpatient or by telephone interview. RESULTS: Among 237 neonates, 6.4% showed delayed development, and 4.6% were cerebral palsy: 3.8%, spastic type; 0.8%, athetoid type, and the others revealed normal motor development. AEP was useful method to predict motor development when this was done at 39.7 0.4 weeks of postmenstrual age (PMA). VEPs failed to show the validity, but there was the typical waveform change in accordance with increase of the postmenstrual age. Median nerve SEPs were valuable for prediction of motor development which were taken at PMA 40.7 0.6 weeks. After 45.3 1.5 weeks of PMA, median nerve SEPs did not reflect motor development outcome significantly. However, posterior tibial SEPs significantly reflect motor outcome regardless of the time of examination. CONCLUSION: Median and posterior tibial SEPs done before 40weeks of PMA are useful tool to predict motor development outcome. When any of these tests showed abnormal findings, follow up study is recommended and posterior tibial SEP study is thought to be the most useful for its predictability. It is necessary to correlate the AEPs and VEPs with hearing and vision whenever abnormal findings are found.

Effects of Clonidine and Epinephrine on Neuropathic Pain in an Experimental Animal Model for Peripheral Neuropathy

OBJECTIVE: To evaluate the effect of clonidine on the experimental neuropathic pain model and to observe whether neuropathic pain is related to the sympathetic nervous system in this model by reversal of allodynia with administration of epinephrine. METHOD: The neuropathic pain was produced by unilateral transection of the superior caudal trunk innervating the rat's tail. Tail withdrawal responses based on mechanical (withdrawal frequency to bending force of von Frey hair 2.0 g) and the thermal (withdrawal latency to tail immersion in a 4degrees C or 40degrees C water with a cut-off time of 15 seconds) stimuli were used. Experiments were performed two weeks after surgery when neuropathic pain had fully been developed. Experimental group by administration of clonidine was examined by tail withdrawal responses at Day 1, Day 3 and Day 5. After one week of wash-out period, reversal of allodynia by administration of epinephrine was examined by the same test. RESULTS: Clonidine significantly decreased the frequency of withdrawal with the mechanical stimuli compared with control (P<0.01), but did not significantly decrease with the cold or warm stimuli. Epinephrine tended to aggravate the mechanical allodynia, but it was not significant compared with the control. CONCLUSION: Clonidine may relieve mechanical allodynia in neuropathic pain, but the mechanism of neuropathic pain that is related to the sympathetic nervous system in this experimental model may be unreliable.

Visual Evoked Potentials in Premature Infants

Visual evoked potentials(VEPs) are the cerebral electrical activities recorded from the occipital scalp following a flash or pattern stimulation and can detect the lesions of sensory visual pathways. Although the VEPs change with the maturation of CNS in children, a few studies have documented the maturational changes in premature infants. Using the light- emitting diode goggles, VEPs were studied in 131 neurologically intact infants of 28~41 weeks gestational age or 34~59 weeks postmenstrual age. The VEPs were analysed by three waveforms; normal, abnormal, and flat, and four patterns; N300, P200-N300, P100-N155-P200-N300, and P100 pattern. Normal waveforms were 63 of 131 VEPs(48.1%). Of the normal waveforms, N300 patterns were 38.1%, P200-N300 36.5%, P100-N155-P200-N300 19.0%, and P100 6.4%. Each pattern correlated with the postmenstrual age. These findings support the hypothesis of VEP pattern changes according to the maturation of the visual system with age.