The role of SEEG in the presurgical decision-making process in MRI-normal mesial temporal lobe epilepsy.

OBJECTIVES: In patients with mesial temporal lobe epilepsy (mTLE) and normal MRI, anterior temporal lobectomy sparing the hippocampus might be considered because of the risk of post-operative memory deficit. However, it is unclear whether some patients with normal MRI and non-invasive EEG and semiological pattern highly suggestive of mesial temporal seizures demonstrate a seizure onset network sparing the hippocampus, potentially warranting surgery. METHODS: A retrospective study of 17 patients with mTLE epilepsy and normal MRI who underwent SEEG. Only patients whose non-invasive presurgical data suggested an unilateral mesial temporal epileptogenic zone (EZ), as defined by combination of ictal semiology and ictal EEG during scalp video-EEG, were included. SEEG data were analyzed using both visual and quantitative approaches. Two EZ organization were defined: (i) EZ involved the hippocampus at the onset of the ictal discharge (HIP group): (ii) patients in whom a delay>1sec was observed between the seizure onset and the involvement of the hippocampus (nHIP group). Non-invasive clinical and functional imaging data, as well as post-operative outcomes, were compared across groups. RESULTS: Eleven patients were included in HIP group and 6 in the nHIP group. In the nHIP group, the maximal epileptogenicity was in the amygdala in five patients and in the entorhinal cortex in one. The hippocampus normalized interictal spiking activity was not different between groups. None of the patients characteristics collected during the non-invasive presurgical workup was associated with the SEEG-based organization of the EZ. Twelve patients underwent a surgical resection, including temporal cortectomy sparing hippocampus in six. Seizure and neuropsychological post-operative outcomes were similar. CONCLUSION: In patients with MRI-normal mTLE, SEEG should be included in the surgical decision-making process because seizure organization cannot be predicted from non-invasive investigations. When hippocampus is not included in the EZ, temporal resection sparing the hippocampus can be considered.

Seizure recurrences in generalized convulsive status epilepticus under sedation: What are its predictors and its impact on outcome?

BACKGROUND: Management of status epilepticus (SE) is focused on the early seizure termination. Refractory SE is an indication for sedation in patients with SE, but up to 75% of patients may be ventilated due to a neurological or respiratory failure. In patients requiring sedation, the clinical assessment is not sufficient to assess seizure control. Identifying those at risk of recurrent seizures could be useful to adapt their management. On the other hand, patients with low risk could benefit from an early withdrawal of sedation to avoid the impact of inappropriate sedation on outcome. OBJECTIVE: To determine the prevalence and the predictors of uncontrolled SE and its impact on outcome in patients with generalized convulsive SE (GCSE) requiring mechanical ventilation (MV). METHODS: We retrospectively included patients admitted to the intensive care unit with GCSE requiring MV. Uncontrolled SE was defined as persistent or recurrent seizures during sedation or within 24hours following withdrawal. A multivariable logistic regression model was used to assess the associated factors. RESULTS: Uncontrolled SE occurred in 37 out of 220 patients (17%). Persistent seizures at admission, higher SAPS II and central nervous system infection were associated with a higher risk of uncontrolled SE. Acute toxic or metabolic etiologies were associated with a decreased risk of uncontrolled SE. In a supplementary analysis, decrease of albumin blood levels was associated with uncontrolled SE. Uncontrolled SE was associated with a poor functional outcome and mortality at 90 days. CONCLUSIONS: Seventeen percent of patients with a GCSE requiring MV suffered from uncontrolled SE. Etiology and persistent seizures at admission were the main predictors of uncontrolled SE. Patients with uncontrolled SE had a longer duration of sedation and MV, a poor functional outcome and a higher mortality. Further studies are required to determine the impact of continuous electroencephalogram monitoring on the clinical course.

Experiences of self-conscious emotions in temporal lobe epilepsy.

Self-conscious emotions (SCEs) with a negative valence (such as shame and guilt) or a positive valence (such as pride) are moral emotions that emerge from self-reflection and self-evaluation processes in social contexts. In some neurologic and psychiatric disorders, experiences of SCEs are dysregulated. The objectives of the present study were to (i) evaluate whether patients with temporal lobe epilepsy (TLE) experience SCEs in the same way as nonclinical (control) participants and (ii) probe the relationships between experiences of SCEs on the one hand and the psychological symptoms frequently diagnosed in patients with TLE (anxiety and depression), the patients' clinical characteristics, and their functional outcomes in everyday life on the other. Sixty-one patients with TLE and 61 matched controls completed a self-questionnaire (the Positive and Negative Affect Schedule (PANAS)) that enabled us to evaluate the extent to which they experienced shame, guilt, and pride. Demographic data, cognitive data, the severity of anxiety symptoms, and the severity of depressive symptoms were recorded for all participants. In patients with TLE, data of clinical characteristics and quality of life were also evaluated. Relative to controls, patients with TLE were more likely to experience negative-valence SCEs to a higher extent and positive SCEs to a lesser extent. The patients who experienced negative-valence SCEs to a higher extent (rather than to a lesser extent) had a higher frequency of seizures, more severe anxiety and depressive symptoms, and a greater prevalence of anxiety and depressive disorders. Furthermore, patients who experienced positive-valence SCEs to a lesser extent (rather than to a higher extent) displayed a higher level of anxiety. Lastly, differences in experiences of SCEs by patients with TLE were associated with a lower quality of life. In conclusion, experiences of SCEs can be dysregulated in patients with TLE. This dysregulation is linked to the patients' clinical and psychological symptoms and quality of life. In this context, SCEs might be a target of interest in the management of epilepsy.

[A national framework for educational programs in epileptic patients, children and adults]. / Un référentiel national pour l'éducation thérapeutique des patients atteints d'épilepsie(s), enfants et adultes.

Epilepsy is a chronic disease with a wide range of presentations occurring at any age. It affects the patient's quality of life, implying a need for numerous healthcare services. Therapeutic education programs (TEPs) are designed to match patient age, disease course, and individual learning abilities. In France, these programs are proposed by the national health authorities (Superior Health Authority), and authorized by the Regional Health Agencies. Two years ago, a Therapeutic Education Programs Commission (TEPC), supported by the French League against Epilepsy (FLAE), was created. The goal was to bring together representative healthcare professionals in a working group in order to standardize practices. This led to the creation of a national reference of healthcare skills specific for children and adults with epilepsy. Five tables, for five "life periods", outline the framework of this professional reference tool. Program personalization, an essential part of TEPs, is necessary to develop a creative atmosphere. This slow process is specific to the various stages of life and can be influenced by the occurrence of various handicaps. Family and caregivers make key contributions to the process. The national framework for therapeutic education in epilepsy serves as a central crossroad where professions can find essential information to create or adapt their own TEPs. In the near future, regional experiences will be documented and collected for regular updates. This professional therapeutic education network will help promote therapeutic education programs and facilitate standard practices. Finally, several TEP files and tools will be shared on the FLAE website available for professional access. Today, the group's goal is to achieve national deployment of this "referential" framework.

The acute inhibition of rapid eye movement sleep by citalopram may impair spatial learning and passive avoidance in mice.

Rapid eye movement (REM) sleep is known to be essential for memory. Hence, REM sleep deprivation impairs memory processes. The frequently prescribed selective serotonin reuptake inhibitors (SSRIs) are known to cause REM sleep deprivation and to impair cognitive performance in humans and rodents. We suggested that impaired memory processes by citalopram in C57/BL6 mice could be explained by the acute inhibition of REM sleep. We hypothesized that those acute citalopram 5 and 10 mg/kg injections induced REM sleep deprivation, altered cognitive performance in passive avoidance, impaired spatial memory compared to controls. Three experiments have been realized: (1) mice received successively physiological saline, injection of citalopram 5 and 10 mg/kg and were recorded by polysomnographic recording after each injection. (2) Cognitive performance was evaluated in the passive avoidance with two groups of mice. One group received citalopram before training and one, after training. (3) Spatial learning was evaluated with another group of animals in the Y-maze test. At 5 and 10 mg/kg, citalopram delayed REM sleep onset and decreased REM sleep amounts (vs. controls). The same doses were administrated in the passive avoidance test and have significantly shortened latency to enter the dark compartment. In the Y-maze, citalopram-treated mice showed a decreased percentage of time spent in the novel arm in contrast to the two other arms compared with controls. We showed that citalopram impaired cognitive performance in behavioral tasks. Those impairments could be linked to REM sleep deprivation induced by citalopram although causal relationship needs to be investigated in further studies.

Childhood-onset narcolepsy, obesity and puberty in four consecutive children: a close temporal link.

Narcolepsy is a rare but disabling condition that causes excessive daytime sleepiness. Interestingly, weight gain is frequent in patients with narcolepsy and it has sometimes been described very early in the course of the disease. Here, we report four consecutive obese children who were referred to our sleep laboratory for excessive daytime sleepiness and suspected sleep apnoea syndrome. They underwent nocturnal polysomnography associated with multiple sleep latency tests. Narcolepsy was diagnosed in all children with a close temporal link between the onset of narcolepsy, obesity and puberty. Scientifically, the relationship between sleep, weight, growth rate and puberty onset is striking and merits further investigation. From the clinical point of view, narcolepsy must be investigated in obese sleepy children along with obstructive sleep apnoea. Indeed, it can be controlled with appropriate treatment but the proper diagnosis relies not only upon nocturnal polysomnography but involves the systematic use of multiple sleep latency tests.

Afferent-induced facilitation of primary motor cortex excitability in the region controlling hand muscles in humans.

Sensory inputs from cutaneous and limb receptors are known to influence motor cortex network excitability. Although most recent studies have focused on the inhibitory influences of afferent inputs on arm motor responses evoked by transcranial magnetic stimulation (TMS), facilitatory effects are rarely considered. In the present work, we sought to establish how proprioceptive sensory inputs modulate the excitability of the primary motor cortex region controlling certain hand and wrist muscles. Suprathreshold TMS pulses were preceded either by median nerve stimulation (MNS) or index finger stimulation with interstimulus intervals (ISIs) ranging from 20 to 200 ms (with particular focus on 40-80 ms). Motor-evoked potentials recorded in the abductor pollicis brevis (APB), first dorsalis interosseus and extensor carpi radialis muscles were strongly facilitated (by up to 150%) by MNS with ISIs of around 60 ms, whereas digit stimulation had only a weak effect. When MNS was delivered at the interval that evoked the optimal facilitatory effect, the H-reflex amplitude remained unchanged and APB motor responses evoked with transcranial electric stimulation were not increased as compared with TMS. Afferent-induced facilitation and short-latency intracortical inhibition (SICI) and intracortical facilitation (ICF) mechanisms are likely to interact in cortical circuits, as suggested by the strong facilitation observed when MNS was delivered concurrently with ICF and the reduction of SICI following MNS. We conclude that afferent-induced facilitation is a mechanism which probably involves muscle spindle afferents and should be considered when studying sensorimotor integration mechanisms in healthy and disease situations.

[Specificity of epileptic seizures in the elderly: A proposed electro-clinical scale]. / Spécificités des crises d'épilepsie chez le sujet âgé : proposition d'un score électro-radioclinique d'orientation.

Diagnosis of epileptic seizure may be difficult in older patients because seizure manifestations are often unusual: confusion, paresis... and because there are multiple differential diagnoses (syncope, transient ischemic attack, transient global amnesia...). To promote and facilitate the diagnosis of seizures in the elderly, neurologists and gerontologists must work together and focus their strategy on two points: firstly, the knowledge of the specific presentation of seizures in elderly patients, and secondly, the adoption of a reasoning based on seizures and not epileptic syndromes. A multidisciplinary group worked on epilepsy of the elderly to elaborate an electro-clinical score which aims to help establish the diagnosis of epilepsy in elderly patients in different clinical settings. This electro-clinical score is based on a systematic review of scientific literature and the recommendations are explicitly linked to supporting evidence. Further, clinical validation of the electro-clinical score is required.

Anticipatory postural adjustments associated with arm movement in Parkinson's disease: a biomechanical analysis.

OBJECTIVE: To study anticipatory postural adjustments (APAs) in Parkinson's disease (PD) via a biomechanical analysis, including vertical torque (Tz). METHODS: Ten patients with PD (in the "off-drug" condition) and 10 age matched controls were included. While standing on a force platform, the subject performed a right shoulder flexion in order to grasp a handle in front of him/her, under three conditions (all at maximal velocity): movement triggered by a sound signal and loaded/non-loaded, self-paced movement. The anteroposterior coordinates of the centre of pressure (COP) and Tz were calculated. RESULTS: A group effect was observed for Tz and COP in patients with PD (compared with controls): the maximal velocity peak appeared later and the amplitude of the COP backward displacement and the area of the positive phase of Tz were lower, whereas the duration of the positive phase of Tz was greater. Interaction analysis showed that the area of Tz was especially affected in the triggered condition and the loaded, self-paced condition. The onset of the COP backward displacement was delayed in the triggered condition. CONCLUSION: Our biomechanical analysis revealed that patients with PD do indeed perform APAs prior to unilateral arm movement, although there were some abnormalities. The reduced APA magnitude appears to correspond to a strategy for not endangering postural balance.

Post-movement beta synchronization in subjects presenting with sensory deafferentation.

OBJECTIVE: We studied the time course and location of post-movement beta synchronization (PMBS) in patients presenting with sensory deafferentation, in order to assess the hypothetical relationship between the PMBS and the cortical processing of movement-related somatosensory afferent inputs. METHODS: We used the event-related synchronization (ERS) method. EEG activity was recorded (via a 128-electrode system) during brisk, unilateral right and left index finger extension by 10 patients presenting with neuropathic pain related to sensory deafferentation. Intra- and post-movement changes in beta source power were calculated relative to pre-movement baseline activity. We compared the PMBS results for the painful and non-painful body sides. Furthermore, PMBS patterns in patients were compared with those in nine healthy volunteers. RESULTS: PMBS pattern related to the painful side had a spatial distribution, with an ipsilateral preponderance, significantly more restricted than PMBS pattern on the non-painful side and in the control group. There were no significant differences between patient PMBS patterns on the non-painful side and those in the control group. CONCLUSIONS: Sensory deafferentation disrupts normal PMBS patterns. SIGNIFICANCE: This work provides additional arguments to the hypothesis supporting that the PMBS is influenced by movement-related somatosensory input processing.

The effects of low- and high-frequency repetitive TMS on the input/output properties of the human corticospinal pathway.

The objective of this study was to characterize the effects of various parameters (notably the frequency and intensity) of repetitive transcranial magnetic stimulation (rTMS) applied over the primary motor (M1) and premotor (PMC) cortices on the excitability of the first dorsalis interosseus (FDI) corticospinal pathway. To this end, we applied a comprehensive input-output analysis after fitting the experimental results to a sigmoidal function. Twenty-six healthy subjects participated in the experiments. Repetitive TMS was applied either over M1 or PMC at 1 Hz (LF) for 30 min (1,800 pulses) or at 20 Hz (HF) for 20 min (1,600 pulses). In the HF condition, the TMS intensity was set to 90% (HF(90)) of the FDI's resting motor threshold (RMT). In the LF condition, the TMS intensity was set to either 90% (LF(90)) or 115% (LF(115)) of the RMT. The FDI input/output (I/O) curve was measured on both sides of the body before rTMS (the Pre session) and then during two Post sessions. For each subject, the I/O curves (i.e., the integral of the FDI motor-evoked potential (MEP) vs. stimulus intensity) were fitted using a Boltzmann sigmoidal function. The graph's maximum slope, S (50) and plateau value were then compared between Pre and Post sessions. LF(115) over M1 increased the slope of the FDI I/O curve but did not change the S (50) and plateau value. This also suggested an increase in the RMT. HF(90) led to a more complex effect, with an increase in the slope and a decrease in the S (50) and plateau value. We did not see a cross effect on the homologous FDI corticospinal pathway, and only PMC LF(90) had an effect on ipsilateral corticospinal excitability. Our results suggest that rTMS may exert a more complex influence on cortical network excitability than is usually reported (i.e. simple inhibitory or facilitatory effects). Analysis of the fitted stimulus response curve indicates a dichotomous influence of both low- and high-frequency rTMS on M1 cortical excitability; this may reflect intermingled effects on excitatory and inhibitory cortical networks.

[Evolution of locomotion disorders in Huntington's disease]. / Caractéristiques évolutives des troubles de locomotion dans la maladie de Huntington.

INTRODUCTION: Locomotion disorders are important in Huntington's disease (HD). Although the rates of evolution of motor, functional or cognitive aspects of HD have been studied, the evolution of locomotion disorders in early stages of the disease remains unknown. OBJECTIVES: To determine the rate of evolution of the HD-associated gait and gait initiation disorders and their correlates. PATIENTS AND METHODS: Eighteen HD patients were recorded with a minimum interevaluation interval of one year. Akinesia was studied by evaluating the anticipatory postural adjustment (APA) phase preceding the first step. We also evaluated gait speed, stride time and stride length. RESULTS: We observed an alteration in the APA phase, whose evolution was correlated with that of akinesia. We also observed a decrease in gait speed, which was due both to an increase in stride time and a decrease in stride length. Stride-to-stride variability did not worsen between both evaluations. CONCLUSIONS: A worsening in both gait initiation and gait performance was observed in HD. Initial weak functional capacity and more severe motor impairment seem to be associated with a faster progression of locomotion parameters in these mildly impaired HD patients.

[Myoclonus and epilepsy: diagnosis and pathophysiology]. / Myoclonies et myoclonies épileptiques: orientation diagnostique et connaissances physiopathologiques.

Myoclonus presents as a sudden brief involuntary jerk triggered by the central nervous system. Electromyographic studies enable determining whether the jerk is caused by a muscular contraction, i.e. positive myoclonus, or by an interruption of muscular activity, i.e. negative myoclonus. Many classifications have been proposed, reflecting our lack of understanding about myoclonus. Myoclonus is a symptom and should never be considered as a diagnosis. Clinical history and physical examination are the basis to diagnosis. Clinical neurophysiology testing can reveal a neuroanatomical localization and certain patterns have some etiological specificity. Etiological hypotheses can be put forward on the basis of clinical and neurophysiological data. The cortex is the most commonly identified source of myoclonus, but the subcortical area and spinal area can also be involved. Myoclonus is considered epileptic when it is combined with an epileptiform discharge on the EEG. The International Classification of Epileptic Syndromes should be applied in this situation. Myoclonic epilepsies are a collection of syndromes in which myoclonic seizures are a prominent feature. Myoclonus can occur as one among several seizure components, as the only manifestation of seizure, or as one of multiple seizure types within an epileptic syndrome. Neurophysiological studies are needed to investigate the pathophysiological mechanisms of the myoclonus. Electrophysiological studies report that myoclonic seizures are produced through a cortical generator via a polysynaptic mechanism acting on muscles. Apparently, the epileptiform discharges stimulate the motor cortex resulting in myoclonus jerk. Despite recent progress, advances are still needed to achieve a better understanding of the pathophysiological mechanisms involved in myoclonus. In myoclonic epileptic syndromes, more useful information can probably be obtained from studies grouping several patients with a same epileptic syndrome than from single case reports.

[Interest of the ketogenic diet in a refractory status epilepticus in adults]. / Intérêt du régime cétogène dans le traitement d'un état de mal épileptique résistant de l'adulte.

INTRODUCTION: Ketogenic diets have been employed for the treatment of intractable epilepsy in children since 1921, although underlying mechanism remains unknown. OBSERVATION: We report the case of a 54-year-old man with partial refractory status epilepticus who exhibited a favourable outcome about seven days after introduction of a ketogenic diet in association with antiepileptic drugs. DISCUSSION: Although its efficiency was largely demonstrated in children, little is known about the impact of a ketogenic diet in adults with refractory epilepsy. CONCLUSION: Introduction of a ketogenic diet requires a multidisciplinary approach. Its usefulness in adult intractable epilepsy and/or refractory status epilepticus merits further study into its efficacy in reducing the frequency of seizures and a possible prolonged effect.

[Medicoeconomic assessment of epilepsy surgery in adults with medically intractable partial epilepsy. Three-year outcomes from a multicenter French cohort]. / Evaluation médicoéconomique de la chirurgie des épilepsies partielles pharmacorésistantes de l'adulte. Résultats à trois ans d'une étude prospective multicentrique française.

PURPOSE: To compare resective surgery and medical therapy in a cost-effectiveness analysis in a multicenter cohort of adult patients with partial intractable epilepsy. POPULATION AND METHODS: Adult patients with partial, medically intractable, potentially operable epilepsy were eligible and followed every year over five years. Effectiveness was defined as one year without seizure. The long-term costs and effectiveness were extrapolated over the patients' lifetime with a Markov model. Productivity (indirect costs) and quality of life (QOLIE-31, SEALS) were also assessed. Changes before and after surgery were compared between the two groups. RESULTS: Two hundred and eighty-nine patients were included (119 with surgery, 161 medically treated, six not eligible, three lost to follow-up). One year after surgery, 81% of the patients were seizure-free; at two and three years, this rate was 78%. In the medical group, these rates were 10, 18, and 15%, respectively. The cost of the explorations was euro 8464; including surgery, it was euro 19,700. In the medical group, the average annual direct costs were between 3500 and euro 6000. At two years after surgery, the annual direct cost decreased to euro 2768, at three years, it was euro 1233, predominately antiepileptic drug costs. Surgery became cost-effective between seven and eight years. In the surgical group, all the quality-of-life scores improved at one year after surgery and were stable during the second and third years. CONCLUSION: Surgical therapy was cost-effective at the middle term even though indirect costs were not considered.

Low frequency repetitive transcranial magnetic stimulation over premotor cortex can improve cortical tremor.

OBJECTIVE: To examine the effects of a 30 min, 1 Hz subthreshold rTMS in a case of cortical tremor which is caused by hyperexcitability of sensorimotor cortex. METHODS: Stimulation was applied over primary and, in a second time, over premotor cortex (M1 and PMC, respectively). Tremor was monitored by accelerometers placed on the index fingers of hands outstretched, before and several times after rTMS. Each rTMS session consisted of 1800 pulses delivered at 1 Hz with an intensity of 90% of resting motor threshold. RESULTS: PMC but not M1 stimulation led to a decrease of the postural tremor (90% decrease of acceleration total spectral power). This functional benefit was associated to normalization of electrophysiologic parameters (short-interval intracortical inhibition and cortical silent period duration). Moreover, when stimulating PMC during two daily sessions, improvement of the tremor was longer than one day stimulation and this benefit was associated with functional improvement. CONCLUSIONS: This study shows that 1 Hz rTMS over premotor cortex can improve cortical tremor. SIGNIFICANCE: These results raise the interest of the motor cortical stimulation as a possible therapeutic target for treatment of action tremor.

Motor representation areas in epileptic patients with focal motor seizures: a TMS study.

PURPOSE: This study used TMS mapping to investigate the motor representation of the abductor pollicis brevis (APB) muscles in a group of patients with focal epilepsy originating in central or pre-central region. METHODS: Eight epileptic patients and eight control subjects participated in the study. The coil was moved in 1.5-cm steps along a grid drawn on the subject's skull over the motor cortex of both hemispheres. At each site, six APB motor responses (evoked by TMS at 1.2 times the resting motor threshold) were recorded and averaged. The peak-to-peak amplitude was measured and plotted against the mediolateral and anteroposterior coil positions. The area of each APB muscle representation was measured and the position of the optimal point was calculated. RESULTS: The resting motor threshold was increased bilaterally in epileptic patients. The maps were distorted in most patients (but not in control subjects), as evidenced by an off-centre optimal point. Interhemispheric differences in APB map areas were greater in patients than in control subjects. However, whether these increases in map area were on the epileptic side or on healthy side depended on the given subject. CONCLUSIONS: The changes in APB representation observed in epileptic patients demonstrate that reorganization occurs within the motor cortex. The heterogeneity of the present results is probably related to different locations of the epileptogenic and/or lesional areas and to a variety of compensatory phenomena that may occur, notably with respect to the disease duration.

Sleep and vigilance in corticobasal degeneration: a descriptive study.

INTRODUCTION: Sleep disorders are common in extrapyramidal diseases, but have rarely been demonstrated in corticobasal degeneration (CBD). METHODS: Here, we describe sleep and vigilance in five consecutive patients with CBD. RESULTS: All five patients had insomnia, four displayed periodic limb movements during sleep (PLMS) and/or restless leg syndrome (RLS), and two had sleep respiratory disorders. None had REM sleep behaviour disorders or excessive daytime sleepiness. CONCLUSIONS: Polysomnography is useful for diagnosing treatable sleep disorders in CBD.

A biomechanical study of gait initiation in Huntington's disease.

BACKGROUND: Akinesia in basal ganglia disorders is essentially defined by delayed movement initiation; the reaction time increases and it becomes difficult (or even impossible) for the subject to initiate movement. A biomechanical study of gait initiation would help evaluate the role of akinesia in early stage Huntington's disease (HD) patients. METHODS: We recorded kinematic, spatiotemporal and angular parameters (using video motion analysis, a force platform and an optoelectronic system) for the first two steps taken by 15 HD patients and 15 gender- and age-matched controls. In order to evaluate the influence of an external cue on gait initiation parameters, we studied two movement paradigms: self-triggered initiation and initiation triggered (cued) by a "beep" sound. We analyzed kinematic, spatiotemporal (the speed, length and duration of the two first steps) and angular parameters (range of joint angles) as well as kinetic data (the trajectory of the centre of pressure (COP); the speed and trajectory of the centre of mass (COM)). RESULTS: HD patients presented akinesia in both externally triggered and self-triggered conditions. Patients had more difficulties with self-triggered gait than with triggered gait. In HD, anticipatory postural adjustments (APAs) were more impaired in self-triggered gait initiation than in cued initiation. Indeed, an alteration in the kinetic parameters revealed a reduction in first step speed in both conditions. Hypokinesia (as assessed by a reduction in the range of angle joints) played an important role in this reduction. CONCLUSION: Akinesia is a major feature of impaired gait initiation in HD. The deficiencies in self-triggered initiation in HD seen here fit with a hypothesis whereby deficient internal cueing can be replaced by an external trigger.