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We looked for an impaired interaction in the primary motor cortex between intracortical inhibitory circuits and circuits fed by somatosensory inputs in patients with writer's cramp. Short-interval intracortical inhibition (sICI) to wrist extensor carpi radialis muscle (ECR) was conditioned by stimulation of antagonist muscle afferents and sICI to first dorsal interosseus (FDI) muscle by homotopic cutaneous afferents stimulation. sICI was assessed at rest and during a tonic contraction of the target muscle. Eighteen patients with writer's cramp (10 having a wrist dystonic posture in flexion during writing and 8 in extension) were compared to 14 control subjects. Peripheral inputs decreased sICI in control subjects. This decrease was lost in patients in both FDI and ECR, regardless of the wrist dystonic posture. By contrast, contraction-induced depression of sICI appeared dependant on the dystonic status of the muscle: depression of sICI to ECR was abolished in patients with wrist dystonic posture in flexion, but not in patients with dystonic posture in extension, sICI even giving way to motor-evoked potential facilitation. Loss of interaction between interneurons mediating sICI and peripheral inputs probably belongs to the initial abnormalities underlying dystonia. Lack of peripherally induced sICI modulation may oppose wrist and/or hand muscles synergies.

International audience; The present studies are designed to further characterise the interneuronal pathway mediating the disynaptic reciprocal group I inhibition between flexors and extensors at the wrist and the elbow levels in humans. In the first series of experiments, we compared the electrical threshold of the reciprocal group I inhibition at the wrist and the elbow level after a prolonged vibration aimed at raising the electrical threshold of the antagonistic activated Ia afferents. Prolonged vibration to the 'conditioning' tendon, which raised significantly the electrical threshold of the inhibition at the elbow level, did not alter it at the wrist level. These results suggest that the dominant input to the relevant interneurones is Ia in origin at the elbow level but Ib in origin at the wrist level. In the second series of experiments, using the spatial facilitation method, we compared the effects on the post-stimulus time histograms of single voluntarily activated motor units of two volleys delivered both separately and together to group I afferents in the nerves supplying the homonymous and antagonistic muscles. At the wrist, but not at the elbow level, the peak of homonymous monosynaptic group I excitation was reduced on combined stimulation, although the antagonistic IPSP was just at the threshold. Because the suppression did not involve the initial bins of the peak, it is argued that the suppression is not due to presynaptic inhibition of Ia terminals, but probably reflects convergence between the homonymous and antagonistic volleys onto the interneurones mediating the disynaptic inhibition. Taken together with the previously reported effects of recurrent inhibition on reciprocal inhibition, these results suggest that inhibition between flexors and extensors is differently organised at the elbow (reciprocal Ia inhibition) and the wrist (non-reciprocal group I inhibition) levels. It is argued that the particular connectivity at the wrist level might correspond to some functional requirements at this ball joint.

Cold-sensitive C afferents of the urinary bladder were studied in adult cats anaesthetised with alpha-chloralose. The bladder was catheterised for fluid instillations and bladder pressure recordings. Pelvic nerve branches were stimulated electrically close to the bladder. Evoked afferent activity was recorded from dissected filaments of the ipsilateral S1-S2 dorsal roots. Responsive afferents were identified using the 'marking technique', based on activity-dependent decrease in C fibre conduction velocity. Of 108 examined bladder C afferents, 14 were activated by innocuous cooling of the bladder wall. Their conduction velocities ranged from 0.6 to 1.7 ms(-1) and their activity dependent decrease in conduction velocity was10 %. All nine cold-sensitive afferents tested responded to menthol exposure. Cold-sensitive C afferents failed to respond to bladder filling with body-warm saline and to active bladder contractions. These characteristics indicate that the cold-sensitive C afferents of the bladder resemble cutaneous cold receptors rather than cold-sensitive mechanoreceptors or nociceptors. It is concluded that the bladder wall is endowed with cold receptors with unmyelinated C afferents in the pelvic nerves and that these afferents are responsible for the bladder cooling reflex.

The autosomal dominant mutation causing myotonic dystrophy (DM1) is a CTG repeat expansion in the 3'-UTR of the DM protein kinase (DMPK) gene. This multisystemic disorder includes myotonia, progressive weakness and wasting of skeletal muscle and extramuscular symptoms such as cataracts, testicular atrophy, endocrine and cognitive dysfunction. The mechanisms underlying its pathogenesis are complex. Recent reports have revealed that DMPK gene haploinsufficiency may account for cardiac conduction defects whereas cataracts may be due to haploinsufficiency of the neighboring gene, the DM-associated homeobox protein (DMAHP or SIX5) gene. Furthermore, mice expressing the CUG expansion in an unrelated mRNA develop myotonia and myopathy, consistent with an RNA gain of function. We demonstrated that transgenic mice carrying the CTG expansion in its human DM1 context (>45 kb) and producing abnormal DMPK mRNA with at least 300 CUG repeats, displayed clinical, histological, molecular and electrophysiological abnormalities in skeletal muscle consistent with those observed in DM1 patients. Like DM1 patients, these transgenic mice show abnormal tau expression in the brain. These results provide further evidence for the RNA trans-dominant effect of the CUG expansion, not only in muscle, but also in brain.

Purpose: We assess clinical and urodynamic results of sacral nerve stimulation for patients with neurogenic (spinal cord diseases) urge incontinence and detrusor hyperreflexia resistant to parasympatholytic drugs.Materials and Methods: Since 1992, 9 women with a mean age of 42.6 years (range 26 to 53) were treated for refractory neurogenic urge incontinence with sacral nerve stimulation. Neurological spinal diseases included viral and vascular myelitis in 1 patient each, multiple sclerosis in 5 and traumatic spinal cord injury in 2. Mean time since neurological diagnosis was 12 years. All patients had incontinence with chronic pad use related to detrusor hyperreflexia. Intermittent self-catheterization for external detrusor-sphincter dyssynergia was used by 5 patients. Social life was impaired and these patients were candidates for bladder augmentation. A sacral (S3) lead was surgically implanted and connected to a subcutaneous neurostimulator after a positive test stimulation trial.Results: Mean followup...

Disynaptic Ia reciprocal inhibition acts, at the spinal level, by actively inhibiting antagonist motor neurons and reducing the inhibition of agonist motor neurons. The deactivation of this pathway in Parkinson's disease is still debated. Disynaptic reciprocal inhibition of H reflexes in the forearm flexor muscles was examined in 15 control subjects and 16 treated parkinsonian patients at rest and at the onset of a voluntary wrist flexion. Two patients were reassessed 18 h after withdrawal of antiparkinsonian medication. At rest, the level of Ia reciprocal inhibition between the wrist antagonist muscles was not significantly different between patients and controls. In contrast, clear abnormalities of this inhibition were revealed by voluntary movements in the patients. In normal subjects, at the onset of a wrist flexion, Ia reciprocal inhibition showed a large decrease, and we argue that this decrease is supraspinal in origin. On the less affected sides of the patients the descending modulation was still present but lower than in controls; on the more affected sides this modulation had vanished almost completely. These movement-induced abnormalities of disynaptic Ia reciprocal inhibition were closely associated with Parkinson's disease but were probably not dependent on L-dopa. They could play a role in the disturbances of precise voluntary movements observed in Parkinson's disease.

The possibility was investigated that changes in heteronymous recurrent inhibition (RI) from quadriceps (Q) to soleus (Sol) and tibialis anterior (TA) motoneurons (MNs) occur during postural tasks requiring co-contraction of Q with one of these muscles. Stimulation of the femoral nerve (FN), which elicited a Q H-reflex discharge, was used to activate Renshaw cells. The resulting inhibition of TA and Sol MNs was assessed using three test responses: (1) the rectified and averaged ongoing electromyogram (EMG) activity in TA or Sol; (2) the motor-evoked potential (MEP) elicited by cortical stimulation in these muscles; and (3) the Sol H reflex. The characteristics of the depression (appearance and increase with the conditioning reflex discharge, short central delay and long duration) are consistent with a Renshaw origin. In addition, results obtained in control experiments (no change in the EMG suppression after an ischaemic blockade of group-I afferents from the leg, time course of the FN-induced depression of the MEP similar to that of the ongoing EMG) made a significant contribution from other pathways activated by FN stimulation unlikely. Posture-related heteronymous RI from Q was compared in different postural tasks at matched levels of background EMG activity: voluntary co-contraction of Q and of the relevant ankle muscle while sitting (control situation), postural co-contraction of Q and TA (while leaning backwards during stance), or contraction of Sol with (preparation for hopping) and without (standing on tip of toes and leaning forwards during stance) associated contraction of the Q. During stance, heteronymous RI from Q was reduced to TA (but not to Sol) while leaning backwards and to Sol in preparation for hopping, but not in the other situations. Thus, RI from Q to TA or Sol was specifically decreased when a co-contraction of the Q and of the relevant muscle operating at the ankle was required to maintain bipedal stance. It is argued that this control of Renshaw cells is descending in origin and contributes to selection of the appropriate synergism in various postural tasks.

New methods have been recently developed to explore selectively presynaptic inhibition of Ia afferents in humans. They have allowed us to describe a highly specialized organisation in these pathways. A differential control has been disclosed during voluntary movements among various motoneuronal pools: at the onset of a selective voluntary contraction presynaptic inhibition of Ia afferents projecting to the `contracting' motoneurons is strongly decreased whereas presynaptic inhibition of Ia afferents to antagonistic or synergistic motoneuronal pools, not involved in the contraction, is increased. Indirect arguments suggested that these modulations are centrally patterned. A differential control has been also disclosed between upper and lower limb pathways. Using transcranial magnetic stimulation to induce a descending corticospinal volley, we have shown that a corticospinal volley inhibits preferentially `presynaptic interneurons'at the lumbar spinal level, an effect which is strengthened by a cutaneous input whereas it preferentially activates `presynaptic interneurons' at the cervical spinal level, an effect which is inverted by a cutaneous input.

The aim of this study was to analyze the urethral pressure responses to cough in men to better characterize the neurogenic mechanisms of male urethral function. A prospective study was carried out on 41 men referred for urodynamic assessment. Urethral pressure profiles at rest and during coughing, and urethral pressure response to voluntary perineal contraction were recorded and analyzed in relation to the neurological status of the patients. Voluntary perineal contraction resulted in a urethral pressure increase (delta pU) of approximately 150 cm H2O in neurologically normal patients. Delta pU could be reduced to any degree in patients with either central or peripheral neurological lesions. Urethral pressure response to cough could be easily classified into two main patterns. Pattern I was characterized by a marked increase in urethral closure pressure during the cough (ratio of urethral to rectal pressure increase: 248 +/- 106%), occurring at the distal part of the posterior urethra. All the neurologically normal patients and the majority of those with upper motoneuron lesions had a pattern I response. Pattern II was defined by the absence of any significant increase in urethral closure pressure at any site of the posterior urethra and was observed in 80% of the patients with signs of lower motoneuron lesions. The pattern of the response to cough was significantly related to the neurological status of the patients (P < 0.001). It was dissociated from the response to voluntary contraction, as would be expected for a reflex versus a voluntary response in neurological patients.

We conducted a retrospective study of the case files of 64 multiple sclerosis (MS) patients presenting severe spasticity, who had received intrathecal (IT) baclofen test injections between 1992 and 2004 in a rehabilitation unit. In almost all cases of our series, IT baclofen was proposed to patients who were no longer able to walk. IT baclofen is a safe and effective treatment to reduce spasticity in MS patients. Despite an advanced stage of the disease at the time of pump placement, the complication rate was low and the efficacy of this treatment was maintained over time.

International audience; This study addresses whether there is excitation from human hand muscles to flexor carpi radialis (FCR) motoneurones mediated through propriospinal circuits and, if so, whether it is used in specific motor tasks. Electrical stimuli to the ulnar nerve at wrist level produced an excitation in FCR motoneurones with characteristics typical of a propriospinally mediated effect: low threshold (0.6 x motor threshold (MT)), a group I effect that was not reproduced by purely cutaneous stimuli, long central delay (4.1 +/- 0.4 ms in single units), suppression when the stimulus intensity was increased, and facilitation of the corticospinal excitation at the premotoneuronal level. Ulnar-induced propriospinally mediated excitation was compared during selective voluntary contractions of the FCR and, at equivalent level of FCR EMG, during tasks in which the FCR was activated automatically in postural contractions rather than voluntarily (grip, pinching and pointing). The excitation was significantly greater during grip (and pinching) than during voluntary FCR contractions and pointing, whether measured in single motor units or tonic EMG activity, or whether the response to motor cortex stimulation was assessed as the compound motor-evoked potential or the corticospinal peak in single units. The discrepancy between the tasks appeared with ulnar intensities above 0.8 x MT and was then present across a wide range of stimulus intensities. This suggests a reduction in the corticospinal control of 'feedback inhibitory interneurones' mediating peripheral inhibition to propriospinal neurones during grip and pinching. The resulting more effective background excitation of propriospinal neurones by the peripheral input from hand muscles could contribute to stabilizing the wrist during grip.

International audience; Effects of electrical stimulation of ulnar and median nerves at wrist level were investigated in post-stimulus time histograms (PSTHs) of single motor units from both flexors and extensors in human arm and forearm. Stimulation of ulnar nerve produced late (mean extra time-after monosynaptic group Ia excitation-10.7 +/- 0.1 ms) high-threshold (>1.2 x motor threshold, MT) excitation, which was not reproduced by purely cutaneous stimulation, in all the investigated motor nuclei except in Extensor Carpi Radialis. Stimulation of median nerve, and of the skin of fingers II and III (at palmar side level), produced short latency inhibition (mean extra time 3.8 +/- 0.3 ms), which was most often truncated or followed by late excitation (mean extra time 11.8 +/- 0.3 ms); both effects were of low threshold (0.8 x MT). Short latency inhibition was very strong, and late excitation was rare and weak in almost all the investigated motor units except in those supplying flexors in forearm, in which the main effect was the late facilitation (stronger than in other motoneurones). Since extra time was not more than 13 ms, it is suggested that the late effects may be mediated through spinal pathways, at least during their 3-5 first ms. Based on the electrophysiological results and on the anatomical characteristics of ulnar and median nerves, it is assumed that ulnar-induced late high-threshold peak in PSTHs might reflect group II excitation in spinal motoneurones, and median-induced modifications in motor unit discharge, mainly cutaneous control of motoneurone discharge. Since the central delay of median-induced inhibition is longer the more caudal the motoneurone, inhibitory propriospinal-like interneurones are supposed to mediate cutaneous inhibitory control from hand upon muscles in arm and forearm. Potential roles of proprioceptive and cutaneous control from hand to more proximal musculature, provided by ulnar and median nerve, respectively, during precise hand movements are discussed.

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Objective: To prospectively evaluate the effect of pump-infused intrathecal baclofen infusion (ITB) in therapeutic doses on sleep quality and on daytime and nighttime respiratory function in patients with severe spasticity. Methods: We prospectively evaluated 20 consecutive patients (mean ± SD age 45 ± 13 years). We assessed spasticity and obtained polysomnography, pulmonary function tests, and resting energy expenditure measurements 1 week before and at least 8 days after pump implantation. Patients stopped oral baclofen upon pump implantation but continued other medications unchanged. We report descriptive statistics as means ± SD. Results: Most of the patients had multiple sclerosis (n = 9) or spinal cord injury (n = 8); there was one case each of cerebral palsy, hereditary spastic paraplegia, and Friedreich ataxia. Before and after ITB initiation, mean Ashworth scores were 2.75 ± 0.85 and 1.15 ± 0.36, and mean spasm scores were 3.75 ± 0.55 and 1.00 ± 0.56. ITB improved total sleep time ( p = 0.05) and sleep efficiency ( p = 0.01) and reduced periodic leg movements ( p = 0.02). ITB did not modify sleep-related respiratory events, lung function tests, CO 2 rebreathing response, or resting energy expenditure. Conclusion: Compared with oral baclofen, intrathecal baclofen infusion did not affect respiratory function and improved sleep continuity. Intrathecal baclofen infusion in therapeutic doses may act at the spinal level rather than at the supraspinal level.

Aims The flow of fluid along the urethra is known to facilitate detrusor contraction during micturition. This reflex, previously described in awake ewes, helps to achieve complete bladder emptying. In anesthetized cats, another urethra to bladder reflex involving urethral cold receptors has been described. The aim of this study was to investigate whether the urethral reflex first described in awake ewes could also be temperature-dependent. Methods Experiments were performed on 10 healthy ewes. Urethral flows were performed by injecting 10 ml saline (ranging from 17 to 43°C) at the level of the proximal urethra. Catheterization of the bladder was performed so that detrusor pressure was continually recorded during the experiments. Results Urethral flows using body temperature saline (37–39°C) consistently evoked detrusor contraction. Urethral flows using saline at temperatures between 40 and 43°C induced detrusor contractions that were not significantly different from those observed at 37–39°C. Urethral flows using saline at temperatures below 37–39°C (17–36°C) resulted in a weaker or absent detrusor contraction. Conclusions In ewes, we have shown that urethral to bladder micturition reflex involving mechanoreceptors is decreased at temperatures below the physiological range. It is suggested that transient receptor potential vanilloid cation channels (e.g., TRPV4 which is activated by sheer/stress flows at near-body temperature) could be involved in this urethra to bladder reflex. In humans, this reflex has hardly been described and is still a matter of debate. Our results reinforce that its full investigation may require systematic use of a range of saline flows at different temperatures. Neurourol. Urodynam. 26:290–295, 2007. © 2006 Wiley-Liss, Inc.

International audience; OBJECTIVE: Myotonias are inherited disorders of the skeletal muscle excitability. Nondystrophic forms are caused by mutations in genes coding for the muscle chloride or sodium channel. Myotonia is either relieved or worsened by repeated exercise and can merge into flaccid weakness during exposure to cold, according to causal mutations. We designed an easy electromyography (EMG) protocol combining repeated short exercise and cold as provocative tests to discriminate groups of mutations. METHODS: Surface-recorded compound muscle action potential was used to monitor muscle electrical activity. The protocol was applied on 31 unaffected control subjects and on a large population of 54 patients with chloride or sodium channel mutations known to cause the different forms of myotonia. RESULTS: In patients, repeated short exercise test at room temperature disclosed three distinct abnormal patterns of compound muscle action potential changes (I-III), which matched the clinical symptoms. Combining repeated exercise with cold exposure clarified the EMG patterns in a way that enabled a clear correlation between the electrophysiological and genetic defects. INTERPRETATION: We hypothesize that segregation of mutations into the different EMG patterns depended on the underlying pathophysiological mechanisms. Results allow us to suggest EMG guidelines for the molecular diagnosis, which can be used in clinical practice.

International audience; StUDY DESIGN: Two case reports of aseptic meningitis after intrathecal baclofen injection. OBJECTIVES: To report an unusual complication of intrathecal baclofen injection during test injections. SETTING: Department of Neurological Rehabilitation, R Poincar??al (Paris-Ile de France-Ouest University). CASE REPORTS: We present two cases of chemical meningitis after intrathecal baclofen injections by lumbar puncture. These cases presented with febrile meningeal syndromes during the 24 h following intrathecal baclofen injection. Direct cerebrospinal fluid (CSF) examination and CSF cultures were negative. An intense cellular reaction was observed with a marked predominance of neutrophils. Meningitis resolved spontaneously over 3-4 days. CONCLUSIONS: Chemical meningitis is a rare complication of intrathecal baclofen injections that must be recognized. It is a diagnosis of exclusion and its pathophysiological mechanism remains unclear.

International audience; Cold hyperalgesia is a major clinical phenomenon, but validated experimental models are still lacking for humans. Topical menthol application has recently been proposed as a possible model for the study of cold pain. We characterized the psychophysical effects of 30% l-menthol in ethanol on glabrous skin in 39 healthy subjects, using a double-blind, randomized, crossover design, with ethanol as a control. Psychophysical testing included an assessment of pain thresholds and detection of mechanical, cold, and heat stimuli, and of the sensations induced by suprathreshold stimuli. Most subjects (90%) perceived a cooling sensation with menthol. Menthol decreased cold pain thresholds and enhanced pain responses to suprathreshold noxious cold stimuli, without affecting responses to other stimuli. Menthol therefore has selective effects on noxious cold processing. No subject displayed signs of skin irritation or redness. These data suggest that 30% menthol application may be a useful experimental model for studies of cold hyperalgesia in humans. The absence of local skin reactions also makes this test potentially suitable for use in patients.

OBJECTIVE: To determine whether a gait-training (GT) machine influenced walking time duration and oxygen consumption in hemiplegic patients. DESIGN: Repeated measures with comparison of 2 groups. SETTING: Physiology laboratories in a rehabilitation hospital. PARTICIPANTS: Seven patients with stroke-related hemiplegia (2 men, 5 women; age, 46+/-11y; time since stroke, 12+/-9wk) and 7 healthy subjects (3 men, 4 women; age, 30+/-7y). INTERVENTIONS: Floor walking (FW) and GT-assisted walking with and without 50% body-weight support (BWS). MAIN OUTCOME MEASURES: Walking time duration, oxygen consumption (Vo(2)), minute ventilation (V(E)), and heart rate. RESULTS: When the condition effect was analyzed independently from the group, mean Vo(2) was higher during FW than during the GT tests (post hoc analysis: FW vs GT, P=.017; FW vs GT+BWS, P

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International audience; OBJECTIVE: To assess the relationships between life satisfaction and disability after a severe traumatic brain injury (TBI). DESIGN: Cross-sectional study, including 75 patients 2 years or more after a severe TBI. METHODS: Life satisfaction was assessed with the Subjective Quality of Life Profile. Impairments, activities and participation were assessed with standardized tests. RESULTS: The satisfaction profile was flat, i.e. the majority of items obtained mean satisfaction scores close to 0, suggesting that participants felt indifferent to these items or in other words that they were neither satisfied nor unsatisfied. Patients were on average slightly dissatisfied with their cognitive functions, physical abilities and self-esteem. A factor analysis revealed three underlying factors. The main finding was that the relationships between life satisfaction and disability were not linear: the lowest satisfaction scores were reported by participants with moderate disability rated by the Glasgow Outcome Scale, while individuals with severe disability did not significantly differ from the good recovery group. CONCLUSION: Life satisfaction is not linearly related to disability after severe TBI.

International audience; In order to assess clock-time estimation (CTE), we asked "what time is it in your opinion?" to 48 recent stroke in-patients, 21 with right (RH), 27 with left hemispheric (LH) lesions, and to 20 control in-patients without brain lesions (C). Errors were measured in terms of the number of minutes by which the estimated clock-time was later (advance errors) or earlier (delay errors) than the real clock-time. CTE was considered pathological when exceeding the mean advance or delay errors observed in control patients plus 2.5 standard deviations. The estimation of the duration of a short psychological interview was also assessed. CTE, and not duration estimation, was disturbed in patients. RH patients made significantly more pathological advance errors than LH patients (43% vs. 12%). This study points out the RH dominance for CTE in stroke patients.

Background The relation between impairment of sensorimotor function and occurrence of phantom limb syndrome (PLS) during regional anesthesia has not been described. This study assessed the temporal relation between PLS and the progression of sensorimotor impairment during placement of a brachial plexus nerve block. Methods Fifty-two patients had their arm randomly placed either alongside their body (group A) or in 90 degrees abduction (group B) immediately after brachial plexus nerve block placement. Responses to pin prick, cold, heat, touch, proprioception, and voluntary movement were assessed every 5 min for 60 min. Meanwhile, patients described their perceptions of the size, shape, and position of their anesthetized limb. Results Phantom limb syndrome occurred 19 +/- 9 min after nerve block placement. Proprioception was impaired and abolished after 22 +/- 9 and 43 +/- 17 min, respectively (P < 0.05 vs. PLS onset). When PLS occurred, responses to pin prick, cold, heat, and proprioception were abolished in 96, 94, 87, and 4% of patients, respectively. Patients were more likely to feel their anesthetized limb in adduction and in abduction in groups A and B (P < 0.05 vs. group A), respectively. After PLS had become motionless, two stereotyped positions were identified: arm adduction, elbow flexion, hand over the abdomen (68% of group A patients) and arm abduction, elbow flexion, hand held close to the homolateral ear (48% of group B patients). Conclusions This study provides a better understanding of the determinants of PLS by showing that the final position of PLS is related both to the abolition of proprioception and the initial position of the anesthetized limb.

International audience; PURPOSE: We assessed the bladder cooling reflex in the awake cat. The bladder cooling reflex is consistently observed in anesthetized adult cats but not in awake, neurologically normal humans. This discrepancy could indicate a state dependant control of the reflex or a species difference. This study was designed to differentiate between these alternatives, MATERIALS AND METHODS: Under ketamine-xylazine 5 animals had an indwelling catheter inserted into the bladder. The cooling reflex was tested by injections of cold saline into the bladder (4C to 8C), lowering its wall temperature to about 30C to 32C. The volume used (5 ml) was subthreshold for the Adelta micturition reflex, as confirmed by control injections of body warm saline. The procedure was repeated with the animals fully awake and it was well tolerated by all of them. Reflex responses were assessed by induced bladder pressures. RESULTS: Typical bladder cooling reflexes with peak pressures greater than 3 kPa were evoked in all cats when in narcotic sleep (group mean +/- CI 7.4 +/- 3.1 kPa). No such reflexes were elicited when the animals were awake (2.0 +/- 1.0 kPa). The difference was significant at the level of individual animals. CONCLUSIONS: The bladder cooling reflex is suppressed in adult cats during wakefulness, as in humans. This state dependent control of the bladder cooling reflex adds to its resemblance to the extensor plantar response (Babinski's sign).

International audience; BACKGROUND: To use a computer assisted analysis of urodynamic tracings (VBN method) in order to propose a quantitative description of the relationship between detrusor activity and firing of efferent motor neurons. METHODS: Modeling of the nervous control implies three definitions of the detrusor excitation: (1) related to the contractile force (EF), (2) related to the calcium turnover (ECa) and (3) ratio of firing motor neurons (rr). The associate variables have been computed from each uroflow recording of healthy volunteers (male and female) and patients (107 men with lower urinary tract symptoms due to benign prostatic enlargement and 138 women with stress urinary incontinence). RESULTS: A "standard excitation" governs all the voidings of healthy volunteers. For 47% of male patients and 75% of female patients, a non-standard excitation is observed: beginning as the standard excitation, then sudden break at a time tc (9.7 +/- 2.5 s for male and 4.0 +/- 2.7 s for women). rr has an all-or-none value in case of standard excitation and exhibits a two steps behavior with after tc: = 0.53 +/- 0.21 for men and 0.41 +/- 0.18 for women (non-significant despite the difference in the origin of disease). CONCLUSION: VBN computer analysis of urodynamic tracings allows to propose a description of the detrusor nervous control: (1) an on-off nervous order rules the "standard" detrusor activity, and (2) a feedback, which probably starts at the urethral level, acts to switch an on-off reduction of the detrusor activity in the other cases.

Functional neuroimaging with positron emission tomography, single photon emission computer tomography, magnetic resonance imaging, and magnetoencephalography have provided powerful tools to elucidate anatomo-functional impairment underlying movement disorders such as dystonic movements. They have revealed that presymptomatic cerebral abnormalities may be a common feature in dystonia whatever the clinical status. Techniques using specific markers have recently focused on the type of receptors that may be dysactivated and on the kind of neurotransmitter that may be dysregulated in dystonia.

International audience; The prefrontal cortex is known to be involved in action planning and in controlling behaviour. Neuropsychological evidence also supports the idea that the prefrontal cortex is generally involved in processing complex events, such as action knowledge. Actions are represented in memory as sequences of goal-directed discrete events. Complex events can be divided into discrete smaller units and organised in a hierarchical manner. The aim of the present study was to investigate the ability of 9 patients with prefrontal lesion and 12 healthy controls to parse action sequences into meaningful events. Subjects were requested to detect the transitions between events under three different orientation instructions: (1) spontaneous; (2) small events; and (3) large event. Both normal subjects and patients identified significantly more events under the small-oriented condition. However, contrary to normal controls (NCs), patients with prefrontal damage showed considerable difficulties in detecting large event units than small event units. These results strongly suggest that prefrontal cortex is specifically involved in parsing and recognising clusters of action sequences. These findings also show that the way in which instructions orient subjects' attention, has an effect on how action information is encoded and represented in memory.

The present studies were designed to increase an existing limitation on the size of the H reflex by accentuating an inhibitory effect of group I afferents in the test volley. They were precipitated by the observation that, during strong voluntary contractions of quadriceps (Q), the late deep peroneal (DP) facilitation of the Q H reflex was suppressed but the facilitation of the ongoing EMG was not. The effects of conditioning stimuli to DP, superficial peroneal (SP) and articular afferents on the excitation of Q motoneurones (MNs) produced by femoral nerve (FN) stimulation were assessed in 11 healthy human subjects using the H reflex of vastus intermedius or the peak of group I excitation in post-stimulus time histograms (PSTHs) of single motor units (MUs) in vastus lateralis. The suppression of the late H reflex facilitation was observed during strong contractions after stimulation of DP and articular afferents, and at rest when DP and SP volleys were combined. In all single MUs tested, the FN-induced peak of excitation was suppressed by DP stimulation during strong Q contractions and by a combination of conditioning volleys (SP with DP or articular) during weak contractions. By themselves these conditioning volleys did not inhibit the background MU discharge even when delivered together. The suppression did not involve the initial bins of the peak; it began 0.7 ms later than the probable onset of monosynaptic Ia facilitation. It is argued that the suppression is not due to presynaptic inhibition of Ia terminals or to recurrent inhibition, but probably reflects convergence between the conditioning volleys and group I afferents in the test FN volley onto interneurones of the disynaptic non-reciprocal group I inhibition. It is concluded that the size of the H reflex is limited by disynaptic inhibition, and that changes in the excitability of this inhibitory pathway can produce prominent changes in the H reflex.

OBJECTIVE:To define the management of internal acoustic meatus and cerebellopontine angle (CPA) lipomas according to their clinical, histological, and surgical characteristics.METHODS:We report four new cases of CPA lipomas diagnosed in the Department of Otorhinolaryngology–Head and Neck Surgery of Hôpital Pitié-Salpêtrière and review 94 cases reported previously in the literature.RESULTS:Lipomas represented 0.14% of CPA and internal acoustic meatus tumors. Localization was on the left side in 59.9%, on the right side in 37%, and bilateral in 3.1% of the patients. The diagnosis was confirmed radiologically in 33 of 98 patients, surgically in 60 patients, and by autopsy in 5 patients. The most frequent associated symptoms were of cochleovestibular origin, such as hearing loss (62.2%), dizziness (43.3%), and unilateral tinnitus (42.2%). Other associated symptoms involved the facial nerve (9%) or the trigeminal nerve (14.4%). Complete resection was performed in only 32.8% of the patients with frequent cranial nerve involvement. Frequent cranial nerve involvement was seen in 95.4% of all patients. After surgery, patient symptomatology was unchanged in 9.2% of the patients, and 50% were improved; however, new postoperative deficits occurred in two-thirds of the patients. Overall, 72.2% of the patients experienced new postoperative deficits such as hearing loss (64.8%). Preservation of hearing was possible in only 26% of the patients. Only 18% of patients were improved after surgery without any new postoperative deficits.CONCLUSION:Preoperative diagnosis of internal acoustic meatus/CPA lipomas is based on magnetic resonance imaging. The aim of surgery in these cases is not tumor removal but cranial nerve decompression or vestibular transection, and surgery is performed only in patients with disabling and uncontrolled symptoms.

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Modulation of non-monosynaptic excitation from ankle dorsiflexors to quadriceps (Q) motoneurones during human treadmill walking was investigated in 25 healthy human subjects. Stimulation of the common peroneal nerve (CPN) evoked a biphasic facilitation in the rectified and averaged (n = 50) Q electromyographic (EMG) activity between 0 and 100 ms after heel strike. Prior to heel strike, the stimulation had no effect on the Q EMG. The latency of both peaks in the response was too long to be explained by a monosynaptic pathway to Q motoneurones. During voluntary tonic co-contraction of Q and tibialis anterior (TA) while standing, only the first of the two peaks was evoked by the CPN stimulation despite a background EMG activity level in the Q and TA muscles corresponding to that observed 30-60 ms after heel strike during walking. Stimulation of cutaneous nerves did not evoke a similar biphasic facilitation in the Q motoneurones, which suggests that muscular afferents mediate the response. The second peak had a higher threshold than the earlier peak. During cooling of the CPN, the latency of the second peak was more prolonged than the latency of the earlier peak. This suggests that afferents of different diameters contributed to the two peaks. It is proposed that afferents from TA assist the contraction of Q during walking via spinal interneurones to stabilize the knee joint and maintain upright posture during walking.

Study of activity in segmental pathways can help in understanding the pathophysiology of clinical disorders due to basal ganglia damage. Disynaptic Ia reciprocal inhibition (DI) acts by actively inhibiting antagonistic motoneurones and reducing the inhibition of agonist ones. During movement, activity of interneurones mediating DI is significantly modulated by descending inputs. In Parkinsonian patients, this descending modulation almost completely vanished. Lack of modulation was not dependent on L-DOPA as it occurred in treated patients and was not modified when patients were off medication. A potent heteronymous group II excitation of quadriceps MNs has been recently demonstrated in normal subjects after stimulation of the common peroneal nerve. This group II excitation was significantly enhanced in the rigid lower limb of Parkinsonian patients. We propose that enhanced group II excitation could contribute to rigidity in PD and result from a change in a tonic noradrenergic descending inhibitory control from locus coeruleus.

Our objective was to describe pelvic floor responses with measurement of reflex latency after suprapubic mechanical stimulation. Twenty-one patients without neurological disease were studied. They were 14 women and seven men. The mean age was 51 (SD = 14.2). Motor responses were recorded with a needle electrode inserted in the left bulbocavernosus muscle. Stimulation was delivered with an electromechanical hammer, tapping directly on the suprapubic area. A polyphasic muscular response was always easily elicited in all patients. The man latency was 67.5 milliseconds (SD = 14.7). The reproducibility between the first and second mechanical responses was good with no statistical difference (r=0.966;P = 0.0001). In three patients who underwent cystometry, no rise in detrusor pressure was observed during mechanical stimulation of the suprapubic area. Our study clearly demonstrates a suprapubic bulbocavernosus reflex (SBR). Tapping the suprapubic area is a strong stimulus, reflexively mediated, used in the management of neurogenic bladder to determine a bladder contraction. However, the reflex consisting of pelvic floor muscle contraction after suprapubic stimulation was not specifically studied in humans. Many arguments can be put forth for a polysynaptic reflex (polyphasic response, habituation and short latency of the reflex, mean latency in the habitual values of R2 responses after electrical stimulation of the dorsal nerve of the penis). We hypothesize that the true stimulus is the stimulation of the bladder wall tensoreceptors, the integration level of the SBR is the sacral segments and the efferent limb the pudendal nerve, and afferent pathways could be conducted by pelvic nerve fibers. Competition between a preponderant (or exaggerated) SBR and a bladder contraction after suprapubic tapping may constitute an equivalent of detrusor-sphincter dyssynergia in some suprasacral bladders. Neurourol. Urodynam. 21:210–213, 2002. © 2002 Wiley-Liss, Inc.

Peripheral stimuli facilitate, at a pre-motoneuronal level, the responses elicited in human upper limb motoneurons (MNs) by transcranial magnetic stimulation over the motor cortex (TMS). Several features indicate that the relevant premotoneurones are distinct from segmental interneurones and located rostral to MNs. Thus, corticospinal volleys would have an indirect (propriospinal) pathway to upper limb MNs, in addition to the direct cortico-motoneuronal pathway. Slightly increasing the corticospinal input causes the facilitation to be reversed to inhibition. This is consistent with a well-developed system of inhibitory intemeurones activated by corticospinal and afferent inputs inhibiting propriospinal neurones (PNs). Corticospinal activation of these inhibitory interneurones would explain why propriospinally-mediated corticospinal EPSPs are weak in primate MNs after artificial (electrical or magnetic) activation of the corticospinal system by itself. However, indirect evidence for descending facilitation of PNs can be provided during normal voluntary contractions, while using the modulation of the ongoing EMG or of the H reflex.

The authors report two cases of patients with word deafness. The word deafness occurred after a head injury for the first patient and after an arterio venous malformation embolization for the second patient. MRI demonstrated bilateral lesions of the inferior colliculi but brainstem auditory-evoked potentials (BAEP) were within normal limits. These cases demonstrated that lesions involving the two inferior colliculi induced pure word deafness but do not affect BAEP.

Dystonia has a wide clinical spectrum from early-onset generalized to late-onset sporadic, task-specific forms. The genetic origin of the former has been clearly established. A critical role of repetitive skilled motor tasks has been put forward for the latter, while underlying vulnerability traits are still being searched for. Using magnetoencephalography, we looked for structural abnormalities reflecting a preexisting dysfunction. We studied finger representations of both hands in the primary sensory cortex, as compared in 23 patients with unilateral task-specific dystonia and 20 control subjects. A dramatic disorganization of the nondystonic hand representation was found in all patients, and its amount paralleled the severity of the dystonic limb motor impairment. Abnormalities were also observed in the cortex coding the dystonic limb representation, but they were important only in the most severely affected patients. The abnormal cortical finger representations from the nondystonic limb appear to be endophenotypic traits of dystonia. That finger representations from the dystonic limb were almost normal for the less severely affected patients may be due to intrinsic beneficial remapping in reaction against the primary disorder.

1. Group I projections from intrinsic plantar muscles to motoneurones (MNs) of human leg and thigh muscles were investigated. Changes in firing probability of single motor units (MUs) in the tibialis anterior (TA), peroneus brevis (Per brev), soleus (Sol), gastrocnemius medialis (GM), vastus lateralis (VL), semitendinosus (ST) and biceps (Bi) were studied after electrical stimuli applied to: (i) the tibial nerve (TN) at ankle level, (ii) the corresponding homonymous nerve, and (iii) the skin of the heel, to mimic the TN-induced cutaneous sensation. 2. Homonymous facilitation, attributable to monosynaptic Ia excitation, was found in all the sampled units. Early heteronymous excitation elicited by TN stimulation was found in many MUs. Later effects (3-5 ms central delay) were bigger and more frequently observed: excitation in most TA and Per brev MUs, and inhibition in most Sol, GM and Bi MUs and in many ST and VL MUs. The low threshold (approximately 0.5-0.6 x motor threshold) and the inability of a pure cutaneous stimulation to reproduce these effects (except the late excitation in TA MUs) indicate that they were due to stimulation of group I muscle afferents. 3. The early excitation was accepted to be monosynaptic when its central delay differed from that of the homonymous Ia excitation by less than 0.5 ms. Such a significant TN-induced monosynaptic Ia excitation was found in MUs belonging to all leg and thigh motor nuclei tested. Although its mean strength was relatively weak, it is argued that these monosynaptic connections might affect already depolarized MNs. 4. The late excitation found in TA and Per brev MUs is argued to be mediated through interneurones located rostral to MNs. 5. The late suppression, found in most Sol, GM and Bi MUs, and in many ST and VL MUs, was the dominant effect. It was accompanied by an inhibition of the Sol and quadriceps H reflexes at rest, and therefore reflects an inhibition directed to MNs. Its long latency is argued to reflect transmission by interneurones located rostral to MNs (the inhibitory counterpart of non-monosynaptic excitation). 6. The functional implications of these connections are discussed with respect to the requirements of the stance phase of human walking and running.

Changes in presynaptic inhibition of Ia terminals directed to flexor carpi radialis (FCR) motoneurones (MNs) were investigated in normal human subjects at rest and during voluntary wrist flexion and extension. To that end, two independent methods were used: (1) the radial-induced D1 inhibition of the FCR H reflex, which assesses the excitability of PAD (primary afferent depolarisation) interneurones controlling presynaptic inhibition of Ia terminals mediating the afferent volley of the FCR H reflex; and (2) the heteronymous monosynaptic Ia facilitation induced in the FCR H reflex by intrinsic muscle Ia afferent stimulation, which assesses the ongoing presynaptic inhibition of Ia terminals. With respect to results at rest, it was found that at the onset of (and during tonic) voluntary wrist flexion, D1 inhibition was reduced and heteronymous monosynaptic Ia facilitation was increased. This suggests that, as in the lower limb, presynaptic inhibition is decreased on Ia terminals projecting to MNs involved in the voluntary contraction. In contrast with results observed in the lower limb, presynaptic inhibition of Ia terminals to FCR MNs was also found to be reduced at the onset of a voluntary contraction involving the antagonistic wrist extensors, suggesting that presynaptic inhibition of Ia terminals projecting to wrist flexors and extensors might be mediated through the same subsets of PAD interneurones. This is in keeping with other features showing that the organisation of reflex pathways between wrist flexors and extensors differs from that observed at other (elbow, ankle) joints.

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In a patient with a limited lesion of the spinal cord at the C6-C7 junction, ulnar and superficial radial-induced modulations of the motor evoked potentials (MEP) and of ongoing electromyographic (EMG) activity were observed in the biceps (above the lesion) but not in the triceps (below the lesion). This suggests an interruption of the axons of cervical propriospinal neurons. This relay transmits an indirect (disynaptic) component of corticospinal excitation to human upper limb motoneurons. Changes in it might be involved in compensatory mechanisms following central motor disorders.