Papers by Soledad Navarro
Archives of Neurology, 2008
Tourette syndrome (TS) is thought to result from dysfunction of the associative-limbic territorie... more Tourette syndrome (TS) is thought to result from dysfunction of the associative-limbic territories of the basal ganglia, and patients with severe symptoms of TS respond poorly to medication. High-frequency stimulation has recently been applied to patients with TS in open studies using the centromedian-parafascicular complex (CM-Pf) of the thalamus, the internal globus pallidus (GPi), or the anterior limb of the internal capsule as the principal target. To report the effect of high-frequency stimulation of the CM-Pf and/or the GPi, 2 associative-limbic relays of the basal ganglia, in patients with TS. Controlled, double-blind, randomized crossover study. Medical research. Three patients with severe and medically refractory TS. Bilateral placement of stimulating electrodes in the CM-Pf (associative-limbic part of the thalamus) and the GPi (ventromedial part). Effects of thalamic, pallidal, simultaneous thalamic and pallidal, and sham stimulation on neurologic, neuropsychological, and psychiatric symptoms. A dramatic improvement on the Yale Global Tic Severity Scale was obtained with bilateral stimulation of the GPi (reduction in tic severity of 65%, 96%, and 74% in patients 1, 2, and 3, respectively). Bilateral stimulation of the CM-Pf produced a 64%, 30%, and 40% reduction in tic severity, respectively. The association of thalamic and pallidal stimulation showed no further reduction in tic severity (60%, 43%, and 76%), whereas motor symptoms recurred during the sham condition. No neuropsychological, psychiatric, or other long-term adverse effect was observed. High-frequency stimulation of the associative-limbic relay within the basal ganglia circuitry may be an effective treatment of patients with TS, thus heightening the hypothesis of a dysfunction in these structures in the pathophysiologic mechanism of the disorder.
Although the subthalamic nucleus is the most frequently used target for surgical treatment of Par... more Although the subthalamic nucleus is the most frequently used target for surgical treatment of Parkinson's disease, the criteria on which it can be identified on T2-weighted images have never been clearly defined. This study was conducted to characterize the precise anatomic distribution of T2-weighted hyposignal in the subthalamic region and to correlate this hyposignal with iron content in the subthalamic nucleus.
Journal of Neurology Neurosurgery and Psychiatry, 2005
Archives of Neurology, 2004
Background: Bilateral subthalamic high-frequency stimulation significantly improves motor functio... more Background: Bilateral subthalamic high-frequency stimulation significantly improves motor functions in patients with advanced forms of Parkinson disease (PD). This favorable effect contrasts with a growing number of reports that the treatment may result in psychiatric complications.
Revue Neurologique, 2009
Rest tremor, one of the main symptoms in Parkinson's disease (PD), is dra... more Rest tremor, one of the main symptoms in Parkinson's disease (PD), is dramatically improved following subthalamic nucleus stimulation (STN). Results are often better than after l-dopa treatment. The occurrence of rest tremor after neurosurgery in patients without preoperative tremor is uncommon. The aim of this work was to investigate the role of subthalamic nucleus stimulation in the appearance of parkinsonian rest tremor. PATIENTS-RESULTS: Thirty PD patients (14%) out of 215 undergoing STN deep brain stimulation had an akinetorigid form of the disease, without preoperative tremor 11 years after onset of the disease. Six of them experienced the appearance of tremor six months after bilateral STN stimulation when the stimulator was switched off in the Off medication state. This de novo parkinsonian tremor was improved by l-dopa treatment and disappeared when the stimulator was turned on. This finding suggests that infraclinical parkinsonian tremor is probably present in all PD patients.
Lumbosacral radiculopathy is a rare complication of radiotherapy and may be challenging to differ... more Lumbosacral radiculopathy is a rare complication of radiotherapy and may be challenging to differentiate from diagnosis of a tumor recurrence. We reviewed the records of three patients with a past history of cancer and radiotherapy who were referred for suspicion of carcinomatous meningitis on lumbar MRI, but whose final diagnosis was radiation-induced lumbosacral radiculopathy. The three patients developed a progressive lumbosacral radiculopathy at 20, 13, and 47 years after lumbar radiotherapy delivered for renal cancer, Hodgkin's disease, and a seminoma, respectively. MRI showed a diffuse, nodular enhancement of the cauda equina nerve roots on T1 sequences, suggestive of leptomeningeal metastasis. A slowly progressive clinical course over several years and negative cerebrospinal fluid cytologic analysis ruled out the diagnosis of carcinomatous meningitis. Because of the radiologic findings, a biopsy was performed in two patients. In the first, a biopsy limited to the arachnoid excluded a malignant infiltration. In the second, a biopsy of the enhancing
Lancet Neurology, 2007
Background We have previously reported the effi cacy and safety of bilateral pallidal stimulation... more Background We have previously reported the effi cacy and safety of bilateral pallidal stimulation for primary generalised dystonia in a prospective, controlled, multicentre study with 1 year of follow-up. Although long-term results have been reported by other groups, no controlled assessment of motor and non-motor results is available. In this prospective multicentre 3 year follow-up study, involving the same patients as those enrolled in the 1 year follow-up study, we assessed the eff ect of bilateral pallidal stimulation on motor impairment, disability, quality of life, cognitive performance, and mood.
Archives of Neurology, 2004
High-frequency stimulation of the subthalamic nucleus (STN) is a neurosurgical alternative to med... more High-frequency stimulation of the subthalamic nucleus (STN) is a neurosurgical alternative to medical treatment in levodopa-responsive forms of Parkinson disease. The mechanism of action of STN stimulation remains controversial, although an inhibition of overactive STN neurons has been postulated. To determine the effects of high-frequency STN stimulation on the neuronal activity of STN neurons in Parkinson disease patients. Single-unit recordings of the neuronal activity of the STN were obtained before, during, and after the application of intra-STN electrical stimulation in 15 Parkinson disease patients. Changes in firing frequency and pattern were analyzed using various combinations of stimulus frequency (range, 14-140 Hz). Stimulation at a frequency greater than 40 Hz applied within the STN significantly decreased the firing frequency and increased the burst-like activity in the firing pattern of STN neurons. An aftereffect was observed in cells that had been totally inhibited during high-frequency stimulation. The beneficial effects of high-frequency stimulation result from a change in the firing pattern of cellular discharge and a blockade of the spontaneous overactivity of STN neurons.
Neurology, 2007
http://www.neurology.org/content/68/4/267.full.html located on the World Wide Web at:
Neurosurgery, 2006
GM1 Type 3 gangliosidosis is a lysosomal storage disorder for which no specific treatment is avai... more GM1 Type 3 gangliosidosis is a lysosomal storage disorder for which no specific treatment is available. It is characterized by progressive generalized dystonia, which is refractory to pharmacological treatment and results in severe disability and life-threatening complications. We performed bilateral pallidal stimulation in a patient with GM1 gangliosidosis and report the 12-month postoperative course. A 24-year old woman presented with genetically confirmed GM1 gangliosidosis, resulting in severe progressive generalized dystonia. Leads were implanted bilaterally into the internal part of the globus pallidus under stereotactic guidance. At follow-up visits, both the patient and the neurologists who performed the assessment were unaware of whether the neurostimulator was on or off. The patient was videotaped with a standardized protocol and scored by an independent expert. After 1 year of follow-up, double-blind comparison of the patient's status with and without neurostimulation showed a 20% improvement, with a significant functional benefit, but no change in disease progression. Although further studies are needed to evaluate this therapeutic approach, this report suggests that pallidal stimulation might be a promising treatment for dystonia caused by GM1 Type 3 gangliosidosis.
Journal of Neurophysiology, 2007
High frequency stimulation of the subthalamic (STN) nucleus is an effective treatment for severe ... more High frequency stimulation of the subthalamic (STN) nucleus is an effective treatment for severe forms of Parkinson's disease (PD). To study the effects of high-frequency STN stimulation on one of the main output pathways of the basal ganglia, single-unit recordings of the neuronal activity of the substantia nigra pars reticulata (SNr) were performed before, during and after the application of STN electrical stimulation in 8 PD patients. During STN stimulation at 14-Hz, no change in either the mean firing rate or the discharge pattern of SNr neurons was observed. STN stimulation at 140-Hz decreased the mean firing rate by 64% and the mean duration of bursting mode activity of SNr neurons by 70% . The SNr residual neuronal activity during 140-Hz STN stimulation was driven by the STN stimulation. How the decrease in rate, and modification of firing pattern of SNr evoked neural activity, during high frequency STN stimulation contribute to the improvement of parkinsonian motor disability remains to be elucidated. Page 2 of 25 Alexander GE. Basal ganglia-thalamocortical circuits: their role in control of movements. J Clin Neurophysiol 11: 420-431, 1994) Bejjani BP, Dormont D, Pidoux B, Yelnik J, Damier P, Arnulf I, Bonnet AM, Marsault C, Agid Y, Philippon J, Cornu P. Bilateral subthalamic stimulation for Parkinson's disease by using three-dimensional stereotactic magnetic resonance imaging and electrophysiological guidance. J Neurosurg 92:615-625, 2000. Benazzouz A, Gao DM, Ni ZG, Piallat B, Bouali-Benazzouz R, Benabid AL. Effect of highfrequency stimulation of the subthalamic nucleus on the neuronal activities of the substantia nigra pars reticulata and ventrolateral nucleus of the thalamus in the rat. Neuroscience 99:289-295, 2000. Boulet S, Lacombe E, Carcenac C, Feuerstein C, Sgambato-Faure V, Poupard A, Savasta M. Subthalamic stimulation-induced forelimb dyskinesias are linked to an increase in glutamate levels in the substantia nigra pars reticulata. J Neurosci 26: 10768-76, 2006. Degos B, Deniau JM, Thierry AM, Glowinski J, Pezard L, Maurice N. Neuroleptic-induced catalepsy: electrophysiological mechanisms of functional recovery induced by high-frequency stimulation of the subthalamic nucleus. J Neurosci 25:7687-7696, 2005. Filali M, Hutchison WD, Palter VN, Lozano AM, Dostrovsky JO. Stimulation-induced inhibition of neuronal firing in human subthalamic nucleus. Exp Brain Res 156: 274-81, 2004. electrophysiological changes of substantia nigra pars reticulata driven by subthalamic stimulation in patients with Parkinson's disease.
Uploads
Papers by Soledad Navarro