Toe walking in children with cerebral palsy: a possible functional role for the plantar flexors.

Equinus and toe walking are common locomotor disorders in children with cerebral palsy (CP) walking barefoot or with normal shoes. We hypothesized that, regardless of the type of footwear, the plantar flexors do not cause early equinus upon initial foot contact but decelerate ankle dorsiflexion during weight acceptance (WA). This latter action promoted by early flat-foot contact is hypothesized to be functional. Hence, we performed an instrumented gait analysis of 12 children with CP (Gross Motor Function Classification System class: I or II; mean age: 7.2 yr) and 11 age-matched typically developing children. The participants walked either barefoot, with unmodified footwear (4° positive-heel shoes), or with 10° negative-heel shoes (NHSs). In both groups, wearing NHSs was associated with greater ankle dorsiflexion upon initial foot contact, and greater tibialis anterior activity (but no difference in soleus activity) during the swing phase. However, the footwear condition did not influence the direction and amplitude of the first ankle movement during WA and the associated peak negative ankle power. Regardless of the footwear condition, the CP group displayed 1) early flattening of the foot and ample dorsiflexion (decelerated by the plantar flexors) during WA and 2) low tibialis anterior and soleus activities during the second half of the swing phase (contributing to passive equinus upon foot strike). In children with CP, the early action of plantar flexors (which typically decelerate the forward progression of the center of mass) may be a compensatory mechanism that contributes to the WA's role in controlling balance during gait.NEW & NOTEWORTHY Adaptation to walking in negative-heel shoes was similar in typically developing children and children with cerebral palsy: it featured ankle dorsiflexion upon initial contact, even though (in the latter group) the soleus was always spastic in a clinical examination. Hence, in children with cerebral palsy, the early deceleration of ankle dorsiflexion by the plantar flexors (promoted by early flattening of the foot, and regardless of the type of footwear) may have a functional role.

Compensatory mechanism involving the hip joint of the intact limb during gait in unilateral trans-tibial amputees.

Hip dynamics in the intact limb during the beginning of stance phase in unilateral trans-tibial amputees (TTA) was studied to evaluate its contribution to compensatory function. We hypothesized (1) an increase in hip total work during H1 power phase (0-30% of gait cycle) including an initial negative phase and (2) an intensification of the hip work in response to uncomfortable gait induced by prosthesis misalignment. Three-dimensional gait analysis was conducted in 17 unilateral TTA and 15 healthy subjects walking at the same self-selected speed in three prosthetic alignments: initial alignment (IA); IA altered either by 6 degrees of internal rotation (IR) or by 6 degrees of external rotation. Patients reported best comfort of gait in IA condition and discomfort mainly in IR condition. During the H1 power phase, in intact limbs a consistent initial flexion movement of the hip (0-8% gait cycle) was associated to negative work and was followed by hip extension and positive work whereas in both prosthetic and control limbs only hip extension and positive work occurred (except in one healthy individual). Absolute value of hip work during H1 phase was significantly higher in intact and prosthetic limbs compared to control limbs in IA condition and was further significantly increased in IR condition only in intact limbs demonstrating a compensatory function of the latter. In intact limbs, early hip negative work contributed to energy absorption in addition to the knee joint probably to compensate the lower energy absorption exerted by the prosthetic limbs.

Compensatory mechanism involving the knee joint of the intact limb during gait in unilateral below-knee amputees.

This study evaluated the asymmetry of knee kinetics during uncomfortable gait induced by prosthesis misalignment to further demonstrate the compensatory function of the knee joint of the intact limb during gait. Three-dimensional gait analysis including knee kinematics and kinetics at the beginning of stance phase was conducted in 15 healthy subjects and 17 unilateral trans-tibial amputees (TTA) walking at self-selected speed in three conditions of prosthetic alignment: initial alignment (IA); initial alignment altered either by 6 degrees of internal rotation (IR) or by 6 degrees of external rotation (ER) applied on the pylon. Patients reported best comfort of gait in IA condition and discomfort mainly in IR condition. Maximum knee flexion and knee total work at power phases K0-K2 were significantly higher in intact limbs compared to prosthetic and control limbs. In intact limbs, these variables had significantly higher values (+10-35%, p<0.05) in IR condition than IA condition whereas these were not altered across conditions in prosthetic limbs. In trans-tibial amputees, inducing uncomfortable gait by internally rotating the prosthetic foot did not alter the knee kinetics of the prosthetic limb, which suggests a protective mechanism. Knee kinetics of the intact limb did alter, which suggests a compensatory mechanism.

[Capacity and performance: ambulatory monitoring under controlled and real-life conditions]. / Evaluation des capacités et des performances: contribution des monitorages de la locomotion en situation d'exercice et de vie réelle.

OBJECTIVES: To determine the value of ambulatory monitoring in assessing human gait. To describe the sensors, the parameters and the ambulatory devices. MATERIALS AND METHODS: Literature review and practical experience about techniques, principles, objectives and limits. RESULTS: Accelerometry is the main technique for ambulatory monitoring because of its reliability, pertinence of signals and software developed for interpretation. Simultaneous monitoring of heart rate response is clinically relevant. Pedometers and actimeters can answer precise clinical questions about amount of walking activity. CONCLUSION: Ambulatory monitoring during long periods (one day or more) is important, especially for rehabilitation medicine because it measures the actual patient activity performed and participation. The simultaneous monitoring of environmental conditions of activity should improve the interpretation of the data collected.

Gait post-stroke: Pathophysiology and rehabilitation strategies.

We reviewed neural control and biomechanical description of gait in both non-disabled and post-stroke subjects. In addition, we reviewed most of the gait rehabilitation strategies currently in use or in development and observed their principles in relation to recent pathophysiology of post-stroke gait. In both non-disabled and post-stroke subjects, motor control is organized on a task-oriented basis using a common set of a few muscle modules to simultaneously achieve body support, balance control, and forward progression during gait. Hemiparesis following stroke is due to disruption of descending neural pathways, usually with no direct lesion of the brainstem and cerebellar structures involved in motor automatic processes. Post-stroke, improvements of motor activities including standing and locomotion are variable but are typically characterized by a common postural behaviour which involves the unaffected side more for body support and balance control, likely in response to initial muscle weakness of the affected side. Various rehabilitation strategies are regularly used or in development, targeting muscle activity, postural and gait tasks, using more or less high-technology equipment. Reduced walking speed often improves with time and with various rehabilitation strategies, but asymmetric postural behaviour during standing and walking is often reinforced, maintained, or only transitorily decreased. This asymmetric compensatory postural behaviour appears to be robust, driven by support and balance tasks maintaining the predominant use of the unaffected side over the initially impaired affected side. Based on these elements, stroke rehabilitation including affected muscle strengthening and often stretching would first need to correct the postural asymmetric pattern by exploiting postural automatic processes in various particular motor tasks secondarily beneficial to gait.

Effect on airway caliber of stimulation of the hypothalamic locomotor region.

Airway dilation is one of the many autonomic responses to exercise. Two neural mechanisms are believed to evoke these responses: central command and the muscle reflex. Previously, we found that activation of central command, evoked by electrical and chemical stimulation of the mesencephalic locomotor region, constricted the airways rather than dilated them. In the present study we examined in decerebrate paralyzed cats the role played by the hypothalamic locomotor region, the activation of which also evokes central command, in causing the airway dilator response to exercise. We found that activation of the hypothalamic locomotor region by electrical and chemical stimuli evoked fictive locomotion and, for the most part, airway constriction. Fictive locomotion also occurred spontaneously, and this too, for the most part, was accompanied by airway constriction. We conclude that central command plays a minor role in the airway dilator response to exercise.

Substance P analogues potentiate the pressor response to microinjection of L-glutamate into laminas I and II of the cat dorsal horn.

Microinjection of a substance P analogue (1 mM; 7 or 10 nl) into laminae I and II of the L7 dorsal horn of decerebrate cats significantly potentiated (P < 0.05) the increase in arterial pressure evoked by microinjection of L-glutamate (109 mM; 7 or 10 nl) into these spinal sites. Microinjection of the substance P analogues (i.e., GR73638 and [Sar9,Met(O2)11]-substance P) which were selective NK-1 receptor agonists, had no impact on the cardioacceleration evoked by microinjection of L-glutamate (P > 0.05). In addition, microinjection of these analogues had no effect on the modest and non-significant increase in phrenic nerve discharge evoked by L-glutamate. We conclude that stimulation of NK-1 receptors in the superficial laminae of the dorsal horn potentiates the pressor responses to microinjection of L-glutamate.

Respiratory system reactance as an indicator of the intrathoracic airway response to methacholine in children.

The upper airways may contribute to increases in airway resistance in response to a bronchial challenge, and thus decrease the specificity of such challenge tests to diagnose airway hyperresponsiveness when forced oscillation techniques are used to evaluate changes in respiratory system resistance (Rrs). A concomitent decrease in respiratory system reactance (Xrs) may indicate a change in the intrathoracic airways and/or lung parenchyma, provided that extrathoracic airway wall motion is prevented. To test the value of Xrs in the evaluation of bronchial hyperresponsiveness, we studied the respiratory impedance response to methacholine in 38 children with a history of asthma (aged 6-14.5 years), and compared the results to changes in the forced expiratory volume in one second (FEV1). Rrs and Xrs were measured by the forced oscillation technique with pseudorandom (11 subjects) or sinusoidal (27 subjects) pressure variations applied around the child's head to minimize upper airway wall motion. Changes in Rrs and in Xrs at 12 Hz (Rrs12, Xrs 12) correlated significantly with changes in FEV1 (P < 0.005). A decrease in FEV1 > or = 20% was observed in 23 subjects. When these 23 subjects were compared with the 15 children who did not show significant changes in FEV1, the responding group had larger mean +/- SEM changes in Rrs (116.0 +/- 13.2% vs 60.4 +/- 11.4%, P < 0.006) and in Xrs (-2.1 +/- 0.4 hPa.s/L vs -0.9 +/- 0.3 hPa.s/L, P < 0.03) than the nonresponders. The receiver operating characteristics (ROC) curve analysis was used to assess the diagnostic value, i.e., specificity and sensitivity, of different levels of change in Rrs and Xrs, with reference to FEV1. The overall incidence of false results was similar for Rrs and Xrs. The optimum diagnostic value for Rrs was a 70% increase, which corresponded to a sensitivity of 87% and a specificity of 67%. For Xrs the optimum decision level was -1 hPa.s/L, corresponding to a sensitivity of 70% and a specificity of 80%. It is concluded that Xrs may improve the specificity of the forced oscillation technique in interpreting the airway response to methacholine. This may be of particular interest in young children unable to perform forced expirations.

Respiratory oscillation mechanics in infants with bronchiolitis during mechanical ventilation.

The aim of the study was to describe the pattern of respiratory oscillation mechanics and responses to positive end-expiratory pressure (PEEP) in bronchiolitis. Six infants were studied during the course of mechanical ventilation. A 20 Hz sinusoidal pressure variation was applied at the endotracheal tube where flow was measured with a pneumotachograph. Resistance and reactance obtained from the complex pressure-flow ratio were separated during inspiration (R(rs,i); X(rs,i)) and expiration (R(rs,e); X(rs,e)), and the differences between R(rs,i) and R(rs,e) (deltaR(rs)) and X(rs,i) and X(rs,e) (deltaX(rs)) were calculated. The data were corrected for the mechanical characteristics of the endotracheal tube. The measurements were repeated while PEEP was varied between 0 and 8 hPa. Two infants were found to have normal R(rs) and near-zero X(rs) and both parameters exhibited little change within the respiratory cycle or with varying PEEP. Four infants had high R(rs) at zero PEEP. In two, R(rs,i) was markedly elevated (108.5 and 85.2 hPa.s/L, respectively), and X(rs,i) was markedly negative (-25.0 and -22.5 hPa.s/L, respectively) at zero PEEP, while deltaR(rs) and deltaX(rs) were small. R(rs,i) and the absolute value of X(rs,i) decreased with increasing PEEP. This pattern of oscillation mechanics was consistent with low lung volumes and atelectasis, being reversed by increasing PEEP. In the remaining two subjects, R(rs,i) was moderately elevated (57.8 and 53.6 hPa.s/L, respectively) and X(rs,i) moderately negative (-12.5 and -7.7 hPa.s/L, respectively) at zero PEEP. DeltaR(rs) (-59.8 and -56.5 hPa.s/L, respectively) and delta(rs) (28.1 and 48.7 hPa.s/L, respectively) were large, but were dramatically reduced by increasing PEEP. These patterns were consistent with expiratory airflow limitation. Measurements of respiratory impedance are, therefore, informative in regard to the pathophysiological mechanisms occurring in bronchiolitis during mechanical ventilation, and they may be helpful in setting the level and assessing the effect of PEEP.

The effect of tibio-talar arthrodesis on foot kinematics and ground reaction force progression during walking.

Degenerative osteoarthritis in the subtalar and mid-tarsal joints occurring after tibio-talar arthrodesis is thought to be a consequence of abnormal foot dynamics. We hypothesized that the forward tilt of the tibia during stance induces early heel-off and alteration of the progression of ground reaction force (GRF) after ankle arthrodesis. Three-dimensional gait analysis was performed on nine patients who had an ankle arthrodesis fused in a neutral position and on ten control subjects. Patients walking barefoot were compared to controls. The GRF progression was shifted forward during mid-stance, heel-off occurred earlier and was associated with less anterior tilt of the tibia and a more posterior position of the GRF with reference to the metatarsal heads. The GRF progression, heel-off and tibial tilt were not significantly different between patients and controls when walking in shoes but the GRF was still more posterior at heel-off. Increasing the walking speed worsened the anomalies of foot dynamics. These alterations of foot dynamics are thought to be associated with pathogenic stresses applied to the mid-foot.

The effect of inturning of the foot on knee kinematics and kinetics in children with treated idiopathic clubfoot.

OBJECTIVE: To assess the effect of internal foot progression angle (inturning) on knee dynamics in children with treated clubfeet. DESIGN: Prospective study dividing a population of clubfeet according to the factor inturning. BACKGROUND: Excessive internal or external foot progression angle increases knee flexion by a backward shift of the ground reaction force to the knee joint in children with cerebral palsy. Similarly, inturning in clubfeet was hypothesized to shift the ground reaction force backwards with reference to the knee joint, increasing the external knee flexion moment and the maximal knee flexion at stance. METHODS: Three-dimensional gait analysis was performed on 20 children with surgically treated clubfeet (n=28) to assess alterations of knee dynamics related to inturning (>7 degrees ) and on 13 normal children. RESULTS: Inturning occurred in 46% of the clubfeet and was associated during stance, at maximal knee flexion, to an increase in maximal knee flexion (+7 degrees ), external knee flexion moment (+60%) and related lever arm to the knee (+100%) and at minimal knee flexion, to a reduction in external knee extension moment (-62%) and related lever arm (-58%). Inturning was associated with a more frequent prolongation of internal knee extension moment and of rectus femoris activity exceeding 50% of stance. CONCLUSION: Inturning in clubfeet is associated with knee dynamics alteration, which might contribute to the long-term development of knee osteoarthritis. RELEVANCE: The therapeutic correction of inturning in clubfeet would be of importance if the consecutive knee dynamics alteration is shown by further studies to contribute to long-term degenerative knee pathology.

[Evaluation of per-endoscopic cytology in the identification of Campylobacter pylori on gastric mucosa]. / Evaluation de la valeur de la cytologie perendoscopique dans l'identification du "Campylobacter pylori" sur la muqueuse gastrique.

The presence of Campylobacter pylori on gastric mucosa was evaluated by touch cytology of gastric biopsies in a series of 100 patients. Results were compared to biopsy cultures. Of 43 culture-positive patients, cytology was positive in 37 (86 p. 100). Cytology was positive in 16 of 57 culture-negative patients, who had peptic ulcer and/or gastritis on biopsy, conditions widely associated with the presence of Campylobacter pylori. Cytologic examination, yielding quick results, is thus a sensitive diagnostic method for Campylobacter pylori. In addition, retrospective studies of previous specimens are possible: among 11 patients with a follow up of more than one year, three of the four Campylobacter pylori carriers subsequently developed an ulcer.

[Georges Gilles of Tourette, pioneer of gait analysis in the nervous system diseases]. / Georges Gilles de la Tourette, initiateur de l'enregistrement de la marche dans les maladies du système nerveux.

Georges Gilles de la Tourette's contribution to neurology goes beyond the description of the neurological disorder named after him. On December 28, 1885, he defended his doctoral thesis devoted to "gait in the diseases of the nervous system, studied by the method of imprints". In collaboration with Albert Londe, he worked for two years in Charcot's department on "a simple method applicable to both healthy and unhealthy patients", establishing the scientific and modern basis of functional exploration of human gait. The purpose was to "record the modifications of the gait and to fix them permanently, using suitable devises to guarantee not only rigorous comparison, but also to prevent observers, making use of the same method, from disputing or canceling the results completely independent of the experimenter himself". Georges Gilles de la Tourette defined the various characteristic parameters and provided the normal reference values in males and females, determining the physiological asymmetry of steps. He described spastic gait, shaking palsy, and locomotor ataxia. He distinguished between disorders of nervous control and related joint diseases. He also classified gait disorders occurring during hemiplegia. Modern development of kinetic, kinematic and biomechanical studies is a good illustration of the current relevancy of Gilles de la Tourette's contribution.

[Modality and causes of 259 deaths in a pediatric intensive care unit]. / Modalités et causes de 259 décès dans un service de réanimation pédiatrique.

BACKGROUND: There are few data available from European pediatric intensive care units (PICU) regarding the modes of death and their causes. POPULATION AND METHODS: Two hundred and fifty nine children, not including neonates, died in the PICU over a 7-year period (1987-1993). Data were obtained from a computerized data base and the retrospective review of medical records by two intensivists. Deaths were classified into three groups according to the terminal event: brain death (BD), unsuccessful resuscitation (UR), do-not-resuscitate order and limitation and/or withdrawal of therapy (LWT). RESULTS: BD was the most common mode of death (38%); UR accounted for 34% and LWT for 28% of deaths. There was no significant annual variation in the proportion of BD, UR and LWT. Age and sex were similar in the three groups. The predominant organ system failure involved upon admission was the central nervous system (52%) in the LWT group, and the cardiovascular system (54%) in the UR group. Severe chronic disease (37%) and immunosuppression (19%) were more prevalent in the LWT group than in the BD group. Time from admission to death was longer in the LWT group (median = 119 hours) as compared to the UR group (10 hours) and the BD group (54 hours). Ten percent of the BD patients became organ transplant donors. Sixty-seven per cent of BD patients had medical contraindication for organ donation: parents did not accept organ donation in 61% of potential cases. Thirty deaths (12%) seemed to be avoidable; dehydration from acute infectious gastroenteritis (n = 7) was the most common cause of avoidable death. CONCLUSIONS: The modes of death in our PICU were statistically not different from those seen in two of four North-American PICUs; LWT was less prevalent than in the two other PICUs, but the patient populations were very different (presence of neonates and many cardiovascular surgery patients). Assessment of the severity of illness at admission and of functional outcome in the survivors are mandatory in future studies.

[Clinical and three-dimensional kinematic features of the upper limb after replantation of the hand]. / Evaluation clinique et cinématique 3D du membre supérieur après réimplantation de la main.

INTRODUCTION: Functional assessments of hand replantation after traumatic amputation are considered as good although frequent deficits of long fingers mobility and hand sensitiveness occur. AIMS: To evaluate the capability of handling and the compensatory mechanisms involved in handling. METHODS: Prospective study in eight right-handed males who had distal amputation of the left upper limb with hand replantation for more than two years. Eight males with paired age and handedness served as control. Skin sensitiveness (thread test), mobility (TAM), functional capability (Box and Blocks test, 400 points test) and occupational outcome were assessed. Three-dimensional analysis (opto-electronic device) of the motion of the trunk and the upper limbs (arm, forearm, hand) was made during a pointing and gripping-shifting maneuver and the time of the related phases was measured (dynamometric cube device). Correlation between clinical assessments and three-dimensional analysis were tested. RESULTS: Patients with replantation had a remarkable recovery of the absolute and relative times of the various phases of the handling maneuver. Only the gripping phase was significantly prolonged in patients, this result was correlated with the deficit in motor function and sensitiveness of the replanted hand. The visual control was higher because of the lack of superficial and deep sensitiveness. Compensatory mechanisms involved a lateral shift of the replanted limb segments, probably attributed to the lateral shift of the trunk. CONCLUSION: Patient with a replanted hand develops a homogenesis displacement of the trunk and the pectoral girdle to compensate the shortening and the reduction in active mobility of the hand. This compensatory mechanism, observed in a small scale in healthy too, is efficient with respect to the handling phases.

Knee kinetic pattern during gait and anterior knee pain before and after rehabilitation in patients with patellofemoral pain syndrome.

Patellofemoral pain is likely due to compressive force acting on the patella related in turn to knee extension moment. The latter variable was assumed to be (i) reduced during short-distance free walking in case of patellofemoral pain syndrome and (ii) increased after therapeutic pain reduction. Peak knee extension moment at beginning of stance phase was recorded by three-dimensional gait analysis in 22 controls and in 23 patients with patellofemoral pain syndrome before and after rehabilitation of knee extensors and flexors to reduce the pain. Pain would occur mainly in stressful activities such as stair negotiation or squatting and was quantified by the anterior knee pain scale. Peak knee extension moment was significantly reduced in all the patients before treatment (n=23) compared to controls, although no one had pain during free walking. In the 17 patients who experienced significant post-rehabilitation pain reduction in their stressful activities, the peak knee extension moment was significantly reduced before treatment compared to controls and significantly increased after treatment, reaching values similar to control values. The peak knee extension moment during free walking appears to be a good kinetic variable related to a compensatory mechanism limiting or avoiding anterior knee pain and may be of interest in assessing knee dynamics alteration in patients with PFPS.

Increasing shoe instep improves gait dynamics in patients with a tibiotalar arthrodesis.

Degenerative osteoarthritis in subtalar and midtarsal joints occurring after tibiotalar arthrodesis may be related to biomechanical factors. For patients with tibiotalar arthrodesis walking with their everyday shoes, the ground reaction force is posterior at heel-off and the maximal foot-tibia dorsiflexion is at its upper limit. We hypothesized that increasing the instep of the shoes would improve these abnormalities. Three-dimensional gait analysis was done in nine patients with ankle arthrodesis fused in the neutral position and for 10 control subjects. Four conditions of walking were tested: barefoot, wearing everyday shoes, wearing everyday shoes with the instep increased by 1 cm, and wearing everyday shoes with the instep increased by 2 cm. In the arthrodesis group, the two modified delayed heel-off shoe conditions shifted the ground reaction force closer to the metatarsal heads at heel-off to a normal range, and reduced the maximal foot and tibia dorsiflexion angle. Based on these results, patients with a tibiotalar arthrodesis in the neutral sagittal position may be advised to choose shoes with an instep of approximately 25 mm.

Improved recovery from laryngeal-stimulation-induced apnea by alpha-adrenergic blockade in adult rabbits.

The apnea triggered by laryngeal stimulation (LS) is associated with a redistribution of blood flow towards the heart and the brain that depends upon peripheral vasoconstriction. The circulatory component of the response to LS has been shown to be reduced following injection of large dose of beta-adrenergic agonist that more intriguingly blunted the ventilatory response as well. To test whether the reduction of LS-induced apnea could be related to the decreased magnitude of the peripheral vasoconstruction, the effects of the alpha-adrenergic antagonist urapidil on the ventilatory and blood pressure responses to LS were studied in 6 adult rabbits. alpha-Adrenergic blockade reduced both the rise in blood pressure and the magnitude of hypopnea induced by LS. These results suggest that the circulatory component of the laryngeal chemoreflex, i.e. the peripheral vasoconstruction, contributes to the magnitude of the ventilatory depression.

Touch cytology, a useful diagnostic method for diagnosis of upper gastrointestinal tract infections.

Candida albicans, Campylobacter pylori, and Giardia lamblia are microorganisms that are frequently found in the upper gastrointestinal tract. A cytological smear of biopsies obtained at endoscopy was compared with the pathologic examination of biopsies. Candida albicans was found in 55 patients, Campylobacter pylori in 54, Giardia lamblia in 31; cytology was positive in 43, 46, and 22 cases, respectively, and biopsy in 29, 43, and 22 cases. Cytology was thus the only positive test in 26 cases with Candida albicans (47% of the 55 cases), in 11 cases of Campylobacter pylori (20%), and in nine cases of Giardia lamblia (29%). We believe that the cytological smear of biopsies (touch cytology) is a quick and sensitive method for diagnosing infections of the upper gastrointestinal tract, increasing the diagnostic yield obtained by biopsy alone.

Inhibition of midbrain-evoked tonic and rhythmic motor activity by cutaneous stimulation in decerebrate cats.

The effect of mechanical and electrical stimulation of cervical cutaneous afferents was analysed on both the centrally induced tonic and rhythmic activities in hindlimb antagonist muscle nerves of 16 decerebrate paralysed cats. Electrical stimulation of dorsal midbrain evoked in the nerve to the tibialis anterior muscle (TAn) either rhythmic discharges (n=14), associated with tonic discharges in ten cats, or only tonic discharges (n=4). Centrally induced activity in the ipsilateral nerve to gastrocnemius medialis (GMn) occurred in fewer cats (n=12) and displayed similar patterns as in TAn. Manual traction of the scruff of the neck reduced the TAn tonic and rhythmic discharges (n=6) by 73% (P<0.05) and 71% (P<0.05), respectively, and reduced only the tonic component of GMn discharges (by 41%, n=3). Electrical stimulation (impulses 0.1-0.5 ms, 50 Hz) of cervical nerves belonging to C5 or C6 dermatomes, the intensity (0.4-4 mA) of which induced minimal inhibition of both TAn and GMn discharges, reduced significantly the tonic component of TAn discharges (by 39%, n=4). At higher intensities of electrical cervical nerve stimulation (2-6 mA) inducing maximal inhibitory effect, both tonic and rhythmic activities in TAn and GMn were both significantly reduced by, respectively, 81% and 94% in TAn (n=7), and by 49% and 43% in GMn (n=7). Electrical cervical nerve stimulation consistently reduced the isolated tonic discharge in TAn by 66% (n=4, P<0.05) and in GMn by 23% (n=3) when present. Thus the tonic component was more sensitive to inhibition than the rhythmic component of hindlimb muscle nerve activity.