Nerve conduction study in young children suffering from cerebral palsy

Objectives: Cerebral palsy (CP) is a motor impairment syndrome leading to disorders of movement and posture. Screening of electrophysiological parameters Hoffman reflex (H-reflex and nerve conduction velocities) becomes a necessary for the early detection and management of the disease. The study aimed to assess the various electrophysiological parameters of nerve conduction velocity in CP and age-matched normal children. Matrials and Methods: The present cross-sectional study was performed between children suffering from CP and healthy control. A total of 27 children of 12–24 months of age of either sex were examined. Among them, six children were normal (with age match), seven were diagnosed with spastic CP and remaining 14 children were diagnosed with hypotonic CP The electrophysiological parameters were recorded in the right lower limb (posterior tibial nerve-soleus muscle) of all children. Results: In electrophysiological parameters, H-reflex latency in secs values was significantly decreased in all CP children. The maximum amplitudes of reflexly excitable motor neurons (Hmax) (mV) and Hmax/maximum amplitude of motor response ratio in the gastrocnemius-soleus muscle were significantly increased in spastic CPas compared to control. H-reflex conduction velocity (HRCV) was significantly higher than motor nerve conduction velocity (MNCV) in hypotonic CP children. Conclusion: The electrophysiological parameters were altered in spastic CP children. The electrophysiological parameters in hypotonic CP were within range, indicating they did not suppress the neuronal motor pool. However, HRCV was significantly more than MNCV in hypotonic CP, suggesting some myelination process defect/white matter injury in motor neurons. We concluded that the electrophysiological parameters of the nerve conduction study are a reliable test for the assessment of tone of muscles in children. Thus, it may help in the early initiation of the treatment and therapies in CP children.

In Vitro Evaluation of Carbachol and Endothelin on Contractility of Colonic Smooth Muscle in Hirschsprung’s Disease.

Background: The hypomotility of colon observed in Hirschsprung’s disease (HD) has been attributed to congenital aganglionosis only. So far, it is not clear whether the contractility of colonic smooth muscle in this condition is altered or not. Therefore, the present study attempted to understand the contractile status of colonic segments of HD patients by examining carbachol and endothelin (ET-1) evoked colonic smooth muscle contractions in vitro. Methods: Contractile responses were recorded from strips of colonic segments obtained from HD patients, using organ bath preparations. Cholinergic agonist carbachol and ET-1 along with their antagonists were used to evoke contractile responses. Thereafter, the samples were histopathologically confirmed for HD. Results: Colonic strips of HD did not show any spontaneous contractions but responded to carbachol and ET-1 to a lesser extent. In HD, response of carbachol was blocked by atropine and hexamethonium by nearly 73% and 50% respectively. ET-1 induced contractile responses were blocked by ET-A and ET-B antagonist up to 40%, signifying the possible role of ET-A and ET-B receptors in HD colon contractility. Conclusion: As evidenced by lack of spontaneous contractions and impaired carbachol and ET-1-induced contractile responses, it is concluded that, in addition to aganglionosis, decreased contractility of colonic smooth muscle may contribute to hypomotility observed in patients with HD.

In Vitro Study of Acetylcholine and Histamine Induced Contractions in Colon and Rectum of Adult and Neonate Rats.

Contractile mechanisms of different parts of the gut in adult and neonate may not be identical due to developmental processes. The present study was undertaken to investigate acetylcholine (ACh) and histamine induced contractile responses of colon and rectum in adult and neonatal albino rats. Contractile responses were recorded from isolated in vitro preparations. The dose-response curve for ACh (0.001-100 μM) revealed dose dependent increase in contractile responses. A significantly (P<0.05) greater contractile responses (g/g wet tissue) was observed in rectum as compared to colon. Atropine pretreatment significantly blocked ACh responses in both rectum and colon. The blockade was higher in adult preparations. The dose-response study for histamine (0.001-100 μM) did not show any significant difference between rectum and colon. Histamine (100 μM) induced contractions were significantly (P<0.05) increased after pretreatment with pheniramine (100 μM) in adult rectum. This potentiating response of pheniramine was absent in neonate rectum. Such effect was also not seen in colon of both adult and neonate. The present investigation indicates that the contractile responses induced by ACh are similar in both adult and neonate, excepting that the blocking effect of atropine in colon was more pronounced in adult as compared to neonate. Further, the results also indicated different mechanism of histamine action in adults and neonates as evidenced by the significant enhancement of contractions by pheniramine only in adult rectum. Therefore, the present results indicate the existence of a different cholinergic and histaminergic activity in adult and neonate as well as in rectal and colonic tissue.

In vivo and in vitro bradycardia induced by local anesthetics is potentiated by calcium channel blockers.

The present study examined the interactions of local anesthetics (LA) and calcium channel blockers (CCBs) on rhythmicity of heart using in vivo and in vitro experiments. ECG recordings were made from the anesthetized rats for in vivo preparations and spontaneously beating isolated rat right atrial potential for the in vitro experiments. The in vivo experiments with LA showed dose-dependent bradycardia with lignocaine (LIG, 100-500 μg/kg) and bupivacaine (BUP, 10-100 μg/kg). BUP was 4-5 times more potent than LIG. Verapamil (VML) and diltiazem (DTZ), CCBs also produced dose (10-100 μg/kg) -dependent bradycardia. However, none of them affected the PR/QT interval or QRS complex. Further, LA-induced bradycardia was potentiated by CCBs. In addition, flattening of P-wave in ECG was observed with doses (10-25 μg/kg) of LA in the presence of CCBs. Similarly, the in vitro experiments demonstrated a concentration-dependent decrease in atrial rate by BUP or VML. The BUP-induced decrease was potentiated in the presence of VML. Thus, the results suggest that CCBs potentiate the LA-induced bradycardia by involving pacemaker activity. Further, the flattening of P-wave in ECG serves as an early indicator of the cardiotoxicity produced by these drugs.

Ptychodiscus brevis toxin decreases the spontaneous activity of rat right atria involving muscarinic receptors and potassium channels.

Marine dinoflagellate Ptychodiscus brevis toxin (PbTx), is known to produce toxic effects on cardiovascular system. The present experiments were conducted to evaluate the effect of synthetic phosphorus containing Ptychodiscus brevis toxin on spontaneously beating right atrium in vitro. The PbTx (0.84-84 microM) decreased the rate and force of right atrial contractions in a concentration-dependent manner. Ethanol, a vehicle present in highest concentration of PbTx, had no effect on atrial rate or force of contraction. Pretreatment with atropine blocked the PbTx-induced decrease in atrial rate and force of contraction. The tetraethylammonium, a potassium channel blocker, blocked the PbTx-induced decrease in atrial rate and force, where as, L-type of calcium channel blocker, nifedipine blocked the PbTx-induced force of contraction but not the rate changes. The results indicate that the PbTx decreased the atrial rate and force of contraction via cholinergic receptors involving K+ channel.

Sleep duration of an individual has adverse influence on auditory episodic memory.

The present study evaluated the influence of habitual sleep duration on episodic memory in a wakeful state. Episodic memory was assessed for auditory and visual processing pathways. A total of 96 medical students (53 male and 43 female, between the age group 18-23 years) accustomed to different sleep durations volunteered in the tests. The tests included auditory free recall of 10 common words, pictorial free recall of 10 pictures and recognition of 10 miniature animal replicas with 10 distracters. There was no gender-related difference in the visual and the auditory memory scores. The visual episodic memory scores were similar in persons sleeping longer or shorter duration. On the other hand auditory memory scores were significantly lower in persons accustomed to >10 h sleep. The results indicate the importance of sleep duration on episodic memory processing of learned material even during wakeful state specially which involves auditory system.

Ca2+ -free medium enhances the magnitude of slow peak in compound action potential of frog sciatic nerve in vitro.

The present investigation was carried out to know the effect of Ca2+ on different peaks of compound action potential (CAP) representing the fibers having different conduction velocity. CAP was recorded from a thin bundle of nerve fibers obtained from desheathed frog sciatic nerve. Suction electrodes were used for stimulating and recording purposes. In Ca2+ -free amphibian Ringer, two distinct peaks (Peak-I and Peak-II) were observed. The threshold, conduction velocity (CV), amplitude and duration of Peak-I were 0.32 +/- 0.02 V, 56 +/- 3.0 m/sec, 2.1 +/- 0.2 mV and 0.75 +/- 0.1 ms, respectively. The Peak-II exhibited ten times greater threshold, eight times slower CV, three times lower amplitude and four times greater duration as compared to Peak-I. Addition of 2 mM Ca2+ in the bathing medium did not alter CAP parameters of Peak-I excepting 25% reduction in CV. But, in Peak-II there was 70-75% reduction in area and amplitude. The concentration-attenuation relation of Peak-II to various concentrations of Ca2+ was nonlinear and 50% depression occurred at 0.35 mM of Ca2+. Washing with Ca2+ -free solution with or without Mg2+ (2 mM)/verapamil (10 microM) could not reverse the Ca2+ -induced changes in Peak-II. Washing with Ca2+ -free solution containing EDTA restored 70% of the response. The results indicate that Ca2+ differentially influence fast and slow conducting fibers as the activity of slow conducting fibers is greatly suppressed by external calcium.