Thalamic deep brain stimulation for the treatment of action myoclonus caused by perinatal anoxia.

BACKGROUND: Perinatal anoxia rarely causes myoclonus as the main neurologic abnormality. The exact neuronal mechanism underlying myoclonus induced by perinatal anoxia remains unknown. Some studies have indicated that the development of involuntary movements may be related to the maturation of the thalamus after birth. OBJECTIVES AND METHODS: Here, we describe the first case of a patient who developed action myoclonus after experiencing perinatal anoxia and was successfully treated by chronic deep brain stimulation (DBS) of the thalamus (thalamic DBS). RESULTS AND CONCLUSION: The effectiveness of chronic thalamic DBS in this patient supports the concept of involvement of the thalamus in post-perinatal anoxic myoclonus.

Development of a new rehabilitation system based on a brain-computer interface using near-infrared spectroscopy.

We describe the set-up for an electrical muscle stimulation device based on near-infrared spectroscopy (NIRS), designed for use as a brain-computer interface (BCI). Employing multi-channel NIRS, we measured evoked cerebral blood oxygenation (CBO) responses during real motor tasks and motor-imagery tasks. When a supra-threshold increase in oxyhemoglobin concentration was detected, electrical stimulation (50 Hz) of the biceps brachii muscle was applied to the side contralateral to the hand grasping task or ipsilateral to the motor-imagery task. We observed relatively stable and reproducible CBO responses during real motor tasks with an average accuracy of 100%, and during motor imagery tasks with an average accuracy of 61.5%. Flexion movement of the arm was evoked in all volunteers in association with electrical muscle stimulation and no adverse effects were noted. These findings suggest that application of the electrical muscle stimulation system based on a NIRS-BCI is non-invasive and safe, and may be useful for the physical training of disabled patients.

Effects of electrode implantation angle on thalamic stimulation for treatment of tremor.

Introduction. Chronic thalamic stimulation has been confirmed as an effective treatment for tremor. The optimal target has been commonly accepted to be situated within the ventral thalamus, but a standard trajectory of the deep brain stimulation (DBS) electrode has not yet been established. Materials and Methods. A 53-year-old man with an 11-year history of essential tremor was treated by DBS of the thalamus. In this patient, we had a chance to compare the effects of different trajectory angles of the DBS electrode on tremor. Results. Intraoperative stimulation with the DBS electrode temporarily inserted at a high angle to the horizontal plane of the anterior commissure-posterior commissure (AC-PC) line to cover only the nucleus ventralis intermedius (Vim) was not effective. In contrast, stimulation with the DBS electrode permanently implanted at a low angle, covering a wide area extending from the nucleus ventralis oralis (Vo) to the Vim, reduced the tremor. Conclusion. We report on the case of a patient who showed different effects on tremor depending on the trajectory angle of the DBS electrode to the AC-PC line. The insertion trajectory of the DBS electrode may be an important factor for the treatment of tremor.

Thalamic deep brain stimulation for writer's cramp.

OBJECT: Writer's cramp is a type of idiopathic focal hand dystonia characterized by muscle cramps that accompany execution of the writing task specifically. In this report, the authors describe the clinical outcome after thalamic deep brain stimulation (DBS) therapy in patients with writer's cramp and present an illustrative case with which they compare the effects of pallidal and thalamic stimulation. In addition to these results for the clinical effectiveness, they also examine the best point and pattern for therapeutic stimulation of the motor thalamus, including the nucleus ventrooralis (VO) and the ventralis intermedius nucleus (VIM), for writer's cramp. METHODS: The authors applied thalamic DBS in five patients with writer's cramp. The inclusion criteria for the DBS trial in this disorder were a diagnosis of idiopathic writer's cramp and the absence of a positive response to medication. The exclusion criteria included significant cognitive dysfunction, active psychiatric symptoms, and evidence of other central nervous system diseases or other medical disorders. In one of the cases, DBS leads were implanted into both the globus pallidus internus and the VO/VIM, and test stimulation was performed for 1 week. The authors thus had an opportunity to compare the effects of pallidal and thalamic stimulation in this patient. RESULTS: Immediately after the initiation of thalamic stimulation, the neurological deficits associated with writer's cramp were improved in all five cases. Postoperatively all preoperative scale scores indicating the seriousness of the writer's cramp were significantly lower (p < 0.001). In the patient in whom two DBS leads were implanted, the clinical effect of thalamic stimulation was better than that of pallidal stimulation. During the thalamic stimulation, the maximum effect was obtained when stimulation was applied to both the VO and the VIM widely, compared with being applied only within the VO. CONCLUSIONS: The authors successfully treated patients with writer's cramp by thalamic DBS. Insofar as they are aware, this is the first series in which writer's cramp has been treated with DBS. Thalamic stimulation appears to be a safe and valuable therapeutic option for writer's cramp.

[A case of cerebral arteriovenous malformation revealing repeated intranidal hemorrhage accompanying neovascularization after stereotactic radiosurgery].

We report a patient with cerebral arteriovenous malformation (AVM) revealing growing mass lesion after stereotactic radiosurgery. This 12-year-old female presented headache. CT scan showed hematoma at the head of the right caudate nucleus and angiography showed AVM at the site. LINAC-based stereotactic radiosurgery was performed with the patient. Twenty-three months after the radiosurgery the patient complained headache and CT scan showed hematoma again at the same site, although angiography did not show AVM. Thirty-five months after the radiosurgery mass lesion with enhancement effect was observed at the site and the mass lesion grew gradually thereafter. Thirty-nine months after the radiosurgery the mass lesion was evacuated. Histological examination revealed fibrotic core and surrounding neovascularized area with hemorrhage. The histology shows a new etiology of growing mass lesion after radiosurgery for AVM.

Intraoperative monitoring of the corticospinal motor evoked potential (D-wave): clinical index for postoperative motor function and functional recovery.

The corticospinal motor evoked potential was investigated as a monitoring index of motor function to perform maximal resection of brain tumors located around the motor cortex in 37 patients with glioma. Tumor resections were performed under general anesthesia with muscle relaxant and completely controlled ventilation. No special arrangements for anesthesia were required. Direct cortical stimulation revealed that if one electrode was placed on the posterior half of the precentral gyrus, the D-wave could be recorded even when using an electrode separation of 10 mm, and the amplitude was larger with anodic rather than cathodic stimulation. Monitoring of the D-wave enabled the function of the corticospinal tract to be evaluated selectively. Postoperative persistent motor disturbance remained in six patients who had a decrease of over 30% in amplitude of the D-wave during tumor resection. A decrease of less than 30% may indicate postoperative preservation of motor function, including transient motor disturbance with subsequent complete recovery. Intraoperative monitoring of the D-wave is suitable for open cranial surgery with general anesthesia, can detect the primary motor cortex, and allow maximal resection of brain tumors located around the motor cortex.

Changes in glucose metabolism in cerebral cortex and cerebellum correlate with tremor and rigidity control by subthalamic nucleus stimulation in Parkinson's disease: a positron emission tomography study.

Objective. Employing [(18) F]fluorodeoxyglucose (FDG) positron emission tomography (PET) to assess the correlation between the effect of deep brain stimulation (DBS) on the subthalamic nucleus (STN) and the regional cerebral metabolic rate of glucose (rCMRGlc) in advanced Parkinson's disease patients (N = 8). Materials and Methods. On the basis of patients' diary records, we performed FDG-PET during the off-period of motor activity with on- or off-stimulation by STN-DBS on separate days and analyzed the correlation between changes in motor symptoms and alterations in the rCMRGlc. Result. When FDG-PET was performed, the motor score on the unified Parkinson's disease rating scale (UPDRS) was 64% lower with on-stimulation than with off-stimulation (p < 0.001, Wilcoxon single-rank test). STN-DBS increased the rCMRGlc in the posterior part of the right middle frontal gyrus, which corresponded to the premotor area, and the right anterior lobe of the cerebellum (p < 0.005, paired t-test). No region exhibited a decrease in rCMRGlc. Among the items of the UPDRS motor score, the changes in resting tremor and rigidity of the left extremities showed a significant correlation with the changes in rCMRGlc observed in the right premotor area (p < 0.02 and p < 0.05, respectively, Spearman's rank correlation). Conclusions. STN-DBS either activates the premotor area or normalizes the deactivation of the premotor area. These FDG-PET findings obtained are consistent with the idea that STN-DBS modifies the activities of neural circuits involved in motor control.