[Astasia-abasia: psychogenic and non-psychogenic causes]. / Astasie-abasie : causes psychogènes et non psychogènes.

Astasia-abasia is defined as the inability to stand and to walk, despite sparing of motor function underlying the required balance and gestures. Initially, astasia-abasia was considered a psychogenic gait disorder, but later on, the description of "high-order" gait disorders mimicking this pure functional deficit led authors to refer to "astasia-abasia" as a pure descriptive term, without a presupposed etiological or anatomical substrate. In this paper, the main clinical characteristics of both psychogenic and non-psychogenic astasia-abasia are presented and discussed.

[Basal ganglia deep-brain stimulation for treatment of drug-resistant epilepsy: review and current data]. / La stimulation cérébrale profonde des ganglions de la base comme traitement des épilepsies pharmacorésistantes: revue et données actuelles.

The surgical treatment of intractable epilepsies involving eloquent areas of the cortex is still challenging. Deep-brain stimulation could be an alternative to resective surgery because it can modulate the remote control systems of epilepsy, such as the thalamus and basal ganglia. The surgical experience acquired in the field of movement disorder surgery and the low morbidity of this technic could allow one to apply DBS to intractable epilepsies, such as generalized, motor and bitemporal epilepsies. Here we discuss the main experimental and clinical data reported so far in the literature and taken from our own experience.

Deep brain stimulation of the corpus luysi (subthalamic nucleus) and other targets in Parkinson's disease. Extension to new indications such as dystonia and epilepsy.

Chronic high frequency (130 Hz) stimulation (HFS) of the thalamic target Vim, first used in our group in 1987 as a treatment of tremor of various origins, has been used over the last ten years in 137 patients. Since 1993, this method has been extended to two other targets (subthalamic nucleus (STN): 137 patients and the medial pallidum (GPi): 12 patients), based on recent experimental data in rats and monkeys. STN appears to be a target of major interest, able to control the three cardinal symptoms and to allow the decrease or suppression of levodopa treatment, which then also suppresses levodopa induced dyskinesias. The stereotactic technique is based on the determination of the target using ventriculography, MRI and electrophysiology, with both microrecording of single neuron activity and microstimulation inducing therapeutic symptom suppression and side effects. Chronic electrodes are then placed bilaterally at the best physiologically defined location and then connected to implantable stimulators (either 2 Itrel II or the new double channel Kinetra), operated at 130-185 Hz, 60 ms pulse width, 2.5 to 3.5 volts. There was no operative mortality and permanent morbidity was observed in 3 patients. The mechanisms of action of HFS are not fully understood, but are definitely related to high frequency and are probably different depending on the target. Inhibition of cellular activity or of neural network functions could be induced, by jamming of a retroactive loop for tremor, or by shutdown of neurotransmitter release in STN. Mechanisms within an individual target are also probably different for tremor or for other symptom alleviation. All cardinal symptoms are alleviated from tremor to akinesia and rigidity. This strong improvement allows the decrease of the drug dosage to approximately 30% of the preoperative level, which suppresses the levodopa-induced dyskinesias. The off period dystonias are also suppressed as well as freezings and falls. The effects remain stable over more than 5 years and in the same period, the off stimulation-off medication UPDRS remains stable and does not increase at the usual rate The low rate of permanent complications, the minor side effects and their immediate reversibility, the possibility of bilateral implantation in one session and the long-term persistence of symptom relief are strong arguments which support chronic HFS of STN as the method of choice when a surgical procedure is indicated for the treatment of Parkinson's disease and even more when a bilateral procedure is necessary. Recent data show that STN stimulation could be useful in the treatment of dystonia as well as some forms of epilepsy. It is therefore possible that DBS in STN as well as in other targets could become a potent therapeutic tool in the near future for neurological disorders.

Deep brain stimulation in the treatment of severe dystonia.

A retrospective study of a consecutive series of 19 patients with medically intractable dystonia treated with uni- or bilateral deep brain stimulation (DBS) is reported. A minimal follow-up of 6 months was available, up to eleven years in one patient. The first twelve consecutive patients (4 with primary and 8 with secondary dystonia) were treated with chronic stimulation of the posterior part of the ventrolateral thalamic nucleus (VLp). In this group global functional outcome was improved in 8 patients, although dystonia movement and disability scale scores did not show significant improvement. Of the 12 patients treated first by VLp DBS, three (1 primary and 2 secondary dystonia) underwent pallidal (GPi) DBS after the VLp DBS failed to improve their symptoms. The last seven consecutive patients (5 primary and 2 secondary dystonia) were treated directly with GPi DBS. Extracranial infection prevented chronic GPi DBS in one patient. In another GPi patient, preliminary negative tests with the electrodes discouraged implantation of the stimulators, and the patient was not treated with chronic DBS. In the remaining group of eight patients including those previously treated with VLp DBS, chronic GPi DBS resulted in a significant improvement in the dystonia movement scale and disability scores. Although this is a retrospective study dealing with dystonia of heterogeneous etiology, the results strongly suggest that GPi DBS has a better outcome than VLp DBS.

Review of the functional surgical treatment of dystonia.

A review of functional surgery for dystonia is presented. Recently renewed interest in stereotaxy for dystonia has followed the resurgence of pallidotomy and the introduction of deep brain stimulation (DBS) in Parkinson's disease (PD) in the early 1990s. However, even since the 1950s, small series of patients treated with ablative surgery have been carefully studied, providing useful information, notably regarding the tolerability of surgery. In the setting of dystonia, thalamotomy was first performed with substantial benefits, but some authors outlined the great variability in outcome, and the high incidence of operative side-effects. In the 'modern' era of functional surgery for movement disorders, the globus pallidus internus (GPi) has emerged to be currently the best target for dystonia, based on small series of patients published in the last few years. Both bilateral posteroventral pallidotomy (PVP) and bilateral pallidal stimulation, performed by several teams, have benefited a variety of patients with severe dystonia, the most dramatic improvements being seen in primary dystonia with a mutation in the DYT1 gene. Whereas patients with secondary dystonia have often shown a lesser degree of improvement, some publications have nevertheless reported major benefit. There is today a strong need for carefully controlled studies comparing secondary and primary dystonia, DYT1 and non-DYT1 dystonia, ablative surgery and DBS, with additional assessment of neuropsychological changes, especially in children treated with bilateral pallidal procedures.

Pallido-Luysio-Nigral atrophy revealed by rapidly progressive hemidystonia: a clinical, radiologic, functional, and neuropathologic study.

Pallido-luysio-nigral atrophy (PLNA) is a rare neurodegenerative disease in which the clinical and radiologic correlates have not yet been clearly established. A 62-year-old man insidiously developed dystonic postures, choreoathetoid movements, slowness, and stiffness, which initially affected the right hand and foot and progressively spread to the entire right side. T2-weighted magnetic resonance imaging showed increased signal intensity in both left and right medial pallida and in the left substantia nigra. Tests using HMPAO-SPECT and FDG-PET demonstrated left cortical hyperperfusion and hypermetabolism, whereas the left lenticular nucleus was slightly hypometabolic. At age 65, abnormal movements and postures involved all four limbs and the axis causing major gait disturbances, and facial and bulbar muscles atrophied resulting in dysarthria, dysphagia, and impaired breathing. Diffuse amyotrophy and fasciculations also appeared. Death occurred at age 66, 4 years after onset. At autopsy, severe bilateral neuronal loss and gliosis restricted to the pallidum, the subthalamic nucleus, the substantia nigra, and the hypoglossal nucleus were noted, accounting for the diagnosis of PLNA with lower motor neuron involvement. Progressive hemidystonia with adult onset represents an unusual clinical presentation for this disorder. Moreover, this observation indicates that a diagnosis of PLNA should be considered for specific magnetic resonance imaging, SPECT, and/or PET data, and suggests that in PLNA, pallidal dysfunction might play a key role in the dystonic presentation.