Guillermo Castro

Electrical stimulation of the hippocampal epileptic foci for seizure control: a double-blind, long-term follow-up study.

Summary:  Purpose: Our aim was to evaluate the safety and efficacy of electrical stimulation of the hippocampus in a long‐term follow‐up study, as well as its impact on memory performance in the treatment of patients with refractory mesial temporal lobe epilepsy.

Neuromodulation of the Centromedian Thalamic Nuclei in the Treatment of Generalized Seizures and the Improvement of the Quality of Life in Patients with Lennox–Gastaut Syndrome

Summary:  Purpose: Our aim was to evaluate the efficacy of ESCM (electrical stimulation of the centromedian thalamic nucleus) in treatment of generalized seizures of the Lennox–Gastaut syndrome (LGS) and improvement of patient disability.

Neuromodulation of the inferior thalamic peduncle for major depression and obsessive compulsive disorder

Neuromodulation of the inferior thalamic peduncle is a new surgical treatment for major depression and obsessive-compulsive disorder. The inferior thalamic peduncle is a bundle of fibers connecting the orbito-frontal cortex with the non-specific thalamic system in a small area behind the fornix and anterior to the polar reticular thalamic nucleus. Electrical stimulation elicits characteristic frontal cortical responses (recruiting responses and direct current (DC)-shift) that confirm correct localization of this anatomical structure. A female with depression for 23 years and a male with obsessive-compulsive disorder for 9 years had stereotactic implantation of electrodes in the inferior thalamic peduncle and were evaluated over a long-term period. Initial OFF stimulation period (1 month) showed no consistent changes in the Hamilton Depression Scale (HAM-D), Yale Brown Obsessive Compulsive Scale (YBOCS), or Global Assessment of Functioning scale (GAF). The ON stimulation period (3-5 V, 130-Hz frequency, 450-msec pulse width in a continuous program) showed significant decrease in depression, obsession, and compulsion symptoms. GAF improved significantly in both cases. The neuropsychological tests battery showed no significant changes except from a reduction in the perseverative response of the obsessive-compulsive patient and better performance in manual praxias of the female depressive patient. Moderate increase in weight (5 kg on average) was observed in both cases.

Deep brain stimulation for treatment of the epilepsies: the centromedian thalamic target

Electrical stimulation (ES) of the thalamic centromedian nucleus (CMN) has been proposed as a minimally invasive alternative for the treatment of difficult-to-control seizures of multifocal origin and seizures that are generalized from the onset. ES intends to interfere with seizure propagation in a non-specific manner through the thalamic system. By adopting a frontal parasagittal approach and based on anterior-posterior (AC-PC) commissure intersection, deep brain stimulation (DBS) electrodes are stereotactically inserted. Electrophysiologic confirmation of electrodes position is accomplished by eliciting cortical recruiting responses and direct current (DC) shifts by low- and high-frequency stimulation through the electrodes. Cycling mode of bipolar stimulation has been used at 60-130 Hz, 0.45 msec, 2.5-3.5 V, 1 min ON in one side 4 min OFF, 1 min ON in the other side and 4 min OFF forward and back for 24h. ES of CMN significantly decreases generalized seizures of cortical origin and focal motor seizures. Best results are obtained in non-focal generalized tonic clonic seizures and atypical absences of the Lennox-Gastaut syndrome. Experience has indicated that the most effective target for seizure control is the thalamic parvocellular centromedian subnucleus.

Motor cortex electrical stimulation applied to patients with complex regional pain syndrome

ABSTRACT Motor cortex stimulation (MCS) is useful to treat patients with neuropathic pain syndromes, unresponsive to medical treatment. Complex regional pain syndrome (CRPS) is a segmentary disease treated successfully by spinal cord stimulation (SCS). However, CRPS often affects large body segments difficult to cover by SCS. This study analyzed the MCS efficacy in patients with CRPS affecting them. Five patients with CRPS of different etiologies underwent a small craniotomy for unilateral 20‐grid‐contact implantation on MC, guided by craniometric landmarks. Neurophysiological and clinical tests were performed to identify the contacts position and the best analgesic responses to MCS. The grid was replaced by a definitive 4‐contacts‐electrode connected to an internalized system. Pain was evaluated by international scales. Changes in sympathetic symptoms, including temperature, perspiration, color and swelling were evaluated. Pre‐operative and post‐operative monthly evaluations were performed during one year. A double‐blind maneuver was introduced assigning two groups. One had stimulators turned OFF from day 30–60 and the other from day 60–90. Four patients showed important decrease in pain, sensory and sympathetic changes during the therapeutic trial, while one patient did not have any improvement and was rejected for implantation. VAS and McGill pain scales diminished significantly (p < 0.01) throughout the follow‐up, accompanied by disappearance of the sensory (allodynea and hyperalgesia) and sympathetic signs. MCS is effective not only to treat pain, but also improve the sympathetic changes in CPRS. Mechanism of action is actually unclear, but seems to involve sensory input at the level of the spinal cord.

Bilateral electrical stimulation of prelemniscal radiations in the treatment of advanced Parkinson's disease.

OBJECTIVE Tremor and rigidity have been efficiently controlled by electrical stimulation of contralateral prelemniscal radiations (Raprl) in patients with unilateral Parkinsons disease. The present study determines the effect of bilateral Raprl electrical stimulation in a group of patients with severe bilateral tremor, rigidity, and bradykinesia. METHODS Five patients with Parkinsons disease (Hoehn and Yahr scale, Stage V) underwent bilateral stereotactic electrode implantation. Postoperative magnetic resonance imaging studies confirmed their position. Bipolar chronic electrical stimulation was performed through contiguous contacts of each electrode, which were selected by means of a screening test that explored multiple combinations. Preoperative and 3-, 6-, 9-, and 12-month postoperative evaluations were performed using international rating scales. Postoperative evaluations were performed with 24 hours off medication-on stimulation. RESULTS Contralateral tremor and rigidity were significantly decreased by simple insertion of electrodes in Raprl and returned hours to days later. Contacts for chronic stimulation were located in the area between the red and subthalamic nuclei, including Raprl, zona incerta, and substantia Q. Efficient stimulation had at least one contact in Raprl and in four cases, both contacts were only in Raprl. Stimulation parameters were 90 to 130 Hz, 90 to 330 mus, and 1.5 to 3.5 V. Unified Parkinsons Disease Rating Scale (motor, Part III) scores decreased 65% (P < 0.001), with improvements of 90% in tremor (P < 0.001), 94% in rigidity (P < 0.001), 75% in bradykinesia (P < 0.001), 40% in gait, and 35% in postural stability (P < 0.05) at 1 year. CONCLUSION Raprl electrical stimulation is safe and efficient to treat patients with the Parkinsons disease symptomatic triad. By use of Raprl stereotactic coordinates, electrodes were placed behind the subthalamic nucleus.

The role of neuromodulation of the hippocampus in the treatment of intractable complex partial seizures of the temporal lobe

We present the results of chronic electrical stimulation of the hippocampus (ESH) in 9 patients with complex partial seizures and at least 18 months follow-up. The magnetic resonance imaging (MRI) scan was normal in 5 while in 4 patients it showed hippocampal sclerosis. The seizure frequency ranged from 10 to 50 seizures per month. All patients were submitted to implantation of diagnostic 8-contact bilateral hippocampal depth electrodes to determine the location of epileptic foci. Once the focus was located, the diagnostic electrodes were replaced by deep brain stimulation (DBS) electrodes. Following DBS, all patients improved. With respect to outcome, patients were divided in two groups, one seizure-free (5 patients) and the other with residual seizures (4 patients). Both groups shared similar clinical features. However, the patients who were seizure free had normal MRI scan while those who had residual seizures were being stimulated on a sclerotic hippocampus. We conclude that electrical stimulation of the epileptic hippocampal formation can control mesial temporal seizures. Best results are obtained if we stimulate a hippocampus which does not show sclerosis in the MRI. In these cases, seizures are stopped and the recent memory tests improve even in patients with bilateral foci. This result is of extreme importance to patients who have either intractable seizures and normal MRI or bilateral epileptogenic foci, are excluded as candidates for temporal lobectomy and are left with no other alternative.

Neuromodulation of prelemniscal radiations in the treatment of Parkinson's disease

In patients with Parkinsons disease (PD), tetrapolar electrodes were implanted in the prelemniscal radiations (RAPRL) to treat tremor, rigidity and bradykinesia. Fifteen patients were implanted unilaterally and five patients bilaterally and followed-up for one year. The selection criteria included the presence of unilateral pronounced tremor and rigidity in patients implanted unilaterally or bilateral symptoms including severe bradykinesia in patients implanted bilaterally. In the operating room, the tremor decreased significantly or was abolished following the insertion of the electrode in the RAPRL. This effect was temporary and subsided when the stimulation was off. However, when the stimulator was turned on, the severity of the symptoms and signs decreased significantly. The post-implantation MRI confirmed that the electrode contacts used for stimulation were inserted in RAPRL, a group of fibers located between the red nucleus and subthalamic nucleus, above the substantia nigra, medially to the zona incerta and below the thalamus. The patients were evaluated using the UPDRS part III, before implantation and every 3 months during the first year. Global scores decreased significantly. The pre- and postoperative median values (range in round brackets) were as follows: tremor improved from 3 (2-16) to 1 (2-3) (p<0.001); rigidity was either abolished or decreased markedly from 2 (1-16) to 0 (0-4) (p< 0.001); bradykinesia improved from 2 (0-4) to 1 (0-2) (p<0.001). We conclude that RAPRL, an area anatomically different from STN, is a good target for electrical stimulation in order to treat effectively all the main symptoms of PD.

Optimizing Prelemniscal Radiations as a Target for Motor Symptoms in Parkinson's Disease Treatment

Objective: To better define prelemniscal radiations (Raprl) as a target for the control of tremor and rigidity in Parkinsons disease (PD). Methods: A total of 36 deep brain stimulation (DBS) electrodes were stereotactically implanted in Raprl contralateral to the extremities to be treated. Effects on symptoms were evaluated using UPDRS-III before and after DBS, and significance was determined using the Wilcoxon test. The location of DBS contacts in cases with optimum versus suboptimum results was evaluated using Students t test and percentage improvement correlated through a bivariable Pearson test. The power and percentage of spike components for microelectrode recordings were statistically compared between the target point and structures located above and below. Results: Raprl-DBS improved tremor and rigidity (p < 0.01). The potency of microelectrode recordings indicated that the target was formed by fibers. There was no correlation between demographic characteristics and clinical outcome, and there were no significant differences in stereotactic placement between cases with optimum and suboptimum results. Tremor and rigidity were selectively improved in cases with suboptimum results. Conclusion: Raprl-DBS is an effective treatment for the motor symptoms of PD. Selective improvement of symptoms suggests that the target has different fiber components related to either tremor or rigidity, and variations in improvement between cases may derive from individual variations of the location of these fibers.

Coupled obturator neurotomies and lidocaine intrathecal infusion to treat bilateral adductor spasticity and drug-refractory pain

Spastic diplegia is present in three-fourths of children with cerebral palsy, interfering with gait and frequently accompanied by severe pain. The authors report the case of a 28-year-old woman with history of perinatal hypoxia, who presented with cerebral palsy and severe spastic diplegia (Ashworth Scale Score 4, Tardieu Scale Score 5) and was confined to a wheelchair. She complained of pain in the left hip and knee with mixed neuropathic and somatic components. She consistently rated pain intensity as 10 of 10 on a visual analog scale, and her symptoms were resistant to multiple treatments. The patient underwent selective bilateral adductor myotomies and the implantation of an infusion pump for intrathecal lidocaine application. Postoperative control of pain and spasticity was dramatic (scores of 0 on the Ashworth, Tardieu, and visual analog scales) and persisted throughout a follow-up period of 36 months. This is the first report in the literature of combined selective neurotomies for the treatment of spasticity and chronic lidocaine subarachnoid infusion to treat associated pain. This therapy could represent an alternative to treat spasticity associated with neuropathic and somatic pain.