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Deep brain stimulation (DBS) of the thalamus (Vo/Vim) has become popular as a means of controlling involuntary movements, including post-stroke movement disorders. We have also found that post-stroke movement disorders and motor weakness can sometimes be controlled by motor cortex stimulation (MCS). In some forms of movement disorders, motor dysfunction becomes evident only when patients intend to move their body. We have developed an on-demand type stimulation system which triggers stimulation by detecting intrinsic signals of intention to move. Such a system represents feed-forward control (FFC) of involuntary movements. We report here our experience of DBS and MCS for controlling post-stroke movement disorders, and discuss the value of FFC. Excellent control of post-stroke movement disorders was achieved by conventional DBS and/or MCS in 20 of 28 patients with hemichoreoathetosis, hemiballism tremor, and motor weakness. FFC was tested in 6 patients who demonstrated excellent control of post-stroke postural tremor or motor weakness by conventional DBS or MCS. The on-demand stimulation provided satisfactory FFC in 4 of 4 patients with postural tremor and 2 of 2 patients with motor weakness, when the activity of muscles involved in posturing or intention to move was fed into the system. These findings justify further clinical studies on DBS and MCS in patients with post-stroke movement disorders. The on-demand type stimulation system may also be useful for overcoming various post-stroke movement disorders.

When microelectrode recording of single cell activity is employed for targeting the subthalamic nucleus (STN), multiple sampling of single cells is needed to determine whether the electrode has passed through the ventral boundaries of the STN. In contrast, stepwise recording of multiple cell activities by a semimicroelectrode reveals robust changes in such activities at the dorsal and ventral boundaries. We attempted to quantify changes in multiple cell activities by computing multiple-cell spike density (MSD). We analyzed MSD in 60 sides of 30 patients with Parkinson’s disease. Neural noise level was defined as the lowest cut-off level at which neural noise is separated from larger amplitude spikes. MSD was analyzed at cut-off levels ranging from 1.2 to 2.0-fold the neural noise level in the white matter in each trajectory. Both the dorsal and ventral boundaries were clearly identified by an increase and a decrease (p < 0.0001) in MSD, respectively, in all the 60 sides. The cut-off level of 1.2-fold showed the clearest change in MSD between the STN and the pars reticulata of substantia nigra. MSD analysis by semimicroelectrode recording represents the most practical means of identifying the boundaries of STN.

Introduction. The term “camptocormia” describes a forward-flexed posture. It is a condition characterized by severe frontal flexion of the trunk. Recently, camptocormia has been regarded as a form of abdominal segmental dystonia. Deep brain stimulation (DBS) is a promising therapeutic approach to various types of movement disorders. The authors report the neurological effects of DBS to the bilateral globus pallidum (GPi) in three cases of disabling camptocormia.

Twenty-one cases of a vegetative state (VS) and 5 cases of a minimally conscious state (MCS) caused by various kinds of brain damage were evaluated neurologically and electrophysiologically at 3 months after brain injury. These cases were treated by deep brain stimulation (DBS) therapy, and followed up for over 10 years. The mesencephalic reticular formation was selected as a target in 2 cases of VS, and the CM-pf complex was selected as a target in the other 19 cases of VS and 5 cases of MCS. Eight of the 21 patients emerged from the VS, and became able to obey verbal commands. However, they remained in a bedridden state except for 1 case. Four of the 5 MCS patients emerged from the bedridden state, and were able to enjoy their life in their own home. DBS therapy may be useful for allowing patients to emerge from the VS, if the candidates are selected according to appropriate neurophysiological criteria. Also, a special neurorehabilitation system may be necessary for emergence from the bedridden state in the treatment of VS patients. Further, DBS therapy is useful in MCS patients to achieve consistent discernible behavioral evidence of consciousness, and emergence from the bedridden state.

Our experience of deep brain stimulation of the globus pallidus internus (GPi-DBS) for dystonia is summarized. A total of 5 patients with primary generalized dystonia underwent GPi-DBS. There were 3 males and 2 females. The age at onset of dystonia ranged from 8 to 45 years and the age at surgery for GPi-DBS ranged from 17 to 59 years. Two of the patients had been treated previously by bilateral thalamotomy or unilateral pallidotomy at other clinics and then developed new symptoms or recurrence. All were stimulated bilaterally. No surgical complications were encountered. The symptoms of dystonia were scored by the Burke-Fahn-Marsden dystonia rating scale (BFMDRS). The scores ranged from 18 to 62 before surgery. An improvement in the symptoms of dystonia was observed soon after the initiation of GPi-DBS, and additional progressive improvement was noted during a period of months or even years after surgery. The score at 6 months after surgery reached a level ranging from 4 to 23. The improvement in score ranged from −51% to −92%. GPi-DBS produced a marked effect even in patients who had previously undergone thalamotomy or pallidotomy. At 6 months after surgery, all patients were receiving bipolar stimulation with a wide interpolar distance, using contact 0 or 1 as the cathode and contact 2 or 3 as the anode. Stimulation was being performed at an intensity of around 2.0 V with a pulse width of 0.21 ms at a high frequency ranging from 120 to 140 Hz. GPi-DBS represents an important therapeutic option in many patients with primary generalized dystonia.

It has been reported that parkinsonian and essential tremor can be controlled by deep brain stimulation or radiofrequency lesion within the cluster of cells with a tremor-frequency activity in the ventral thalamic nuclei. However, there have been very few reports about the exact localization of cells with tremor-frequency activity in the ventral thalamic nuclei. In the present study, we investigated the localization of cells with tremor-frequency activity in the ventral thalamic nuclei employing autopower spectrum and coherence analysis. Activity of a total of 130 cells, 63 in patients with parkinsonian tremor and 67 in patients with essential tremor, were recorded from the area anterior to the nucleus ventralis caudalis. Among these cells, 31 cells showed a coherence of greater than 0.4 to the electromyographic activity of both agonist and antagonist muscles. The proportion of cells exhibiting tremor-frequency activity were 26.8% in the nucleus ventralis intermedius (Vim) and 25.0% in the nuclei ventralis oralis posterior et anterior (Vop + Voa). There were no significant differences in proportion by nuclear location or disease. The present study demonstrated that cells with tremor-frequency activity are widely distributed over the area extending from the Vim to the Vop + Voa. This indicates that the best location for placing electrodes for deep brain stimulation or a radiofrequency lesion cannot be defined by identification of cells with tremor-frequency activity alone.

Our experience of deep brain stimulation (DBS) and motor cortex stimulation (MCS) in patients with post-stroke movement disorders and post-stroke pain is reviewed. DBS of the thalamic nuclei ventralis oralis posterior et intermedius proved to be useful in more than 70% of patients with post-stroke involuntary movements (hemiballismus, hemichoreo-athetosis, distal resting and/or action tremor, and proximal postural tremor). The effect of DBS of the thalamic nucleus ventralis caudalis or internal capsule on post-stroke pain was usually disappointing. Excellent pain control can be achieved by MCS in approximately 50% of patients with post-stroke pain. In the course of clinical trials on MCS for the control of post-stroke pain, it was found that co-existent post-stroke involuntary movements (hemichoreo-athetosis and resting tremor) could also be controlled by MCS. Post-stroke involuntary movements, especially those in thalamic syndrome, are sometimes associated with post-stroke pain. In such disorders, involuntary movements are attenuated, but the pain in the same patients is often exacerbated by DBS of the thalamic nuclei ventralis oralis posterior et intermedins. MCS could be the therapy of choice under such circumstances. Subjective improvement of voluntary motor performance, which had been impaired in association with mild or moderate hemiparesis, was reported during MCS by approximately 20% of patients with post-stroke pain. Such an effect on voluntary motor performance appears to be caused by an inhibition of their rigidity. The reversibility of DBS and MCS makes them an important option for the control of post-stroke movement disorders and post-stroke pain.

Twenty-one cases of a persistent vegetative state (PVS) caused by various kinds of brain damage were evaluated neurologically and electrophysiologically at 3 months after the brain injury. The 21 cases were treated by deep brain stimulation (DBS) therapy, and followed up for over 10 years. The stimulation sites were the mesencephalic reticular formation (2 cases) and CM-pf complex (19 cases). Eight of the patients emerged from the PVS, and became able to obey verbal commands. However, they remained in a bedridden state. These 8 cases revealed a desynchronization on continuous EEG frequency analysis. The Vth wave of the ABR and N20 of the SEP could be recorded even with a prolonged latency, and the painrelated P250 was recorded with an amplitude of over 7 µV. The mean survival time of these 8 cases was 6.1 years, as compared to 3.1 years for the other 13 cases. Overall, 4 cases are alive after more than 10 years. DBS therapy may be useful for allowing patients to emerge from a PVS, if the candidates are selected according to neurophysiological criteria. The fact that 19% (4/21) of the PVS cases treated with DBS survived for over 10 years should be stressed in comparison with the usual survival period for the untreated PVS.

We investigated the clinical course and characteristics of the motor deficits in patients who underwent surgical resection of the frontal lobe for tumorous lesions. Only patients who met the following criteria were included in the present study: 1) postoperative MRI revealed that resection of the frontal lobe involved the area closely adjacent to the primary motor cortex, but 2) the D wave of the corticospinal MEP did not decrease in amplitude below 50% of the original level during surgery. The extent of resection was classified into 4 groups. In Group A (6 cases), resection was limited within the area above the superior frontal sulcus and posterior to a line vertical to the line connecting the anterior and posterior commissures at the anterior commissure (AC vertical line). Resection was extended anterior to the AC vertical line in Group B (4 cases) or below the superior frontal sulcus in Group C (5 cases). In Group D (3 cases), resection was extended to both of these two boundaries. Severe motor paresis and/or apraxia of the upper and lower extremities were noted in all patients of Group D immediately after surgery. A complete recovery in the lower extremity was observed in these patients, while disturbance in the fine movements of the upper extremity remained for more than 1 year after the surgery. Disturbance in the fine movements and/or apraxia of the upper extremity were observed immediately after surgery in 2 of the Group A patients (33%), 2 of the Group B patients (50%) and 3 of the Group C patients (60%). However, a rapid recovery occurred in these patients, and only a subtle or mild disturbance remained for more than 1 year after the surgery in one of the Group B and one of the Group C patients. Permanent and severe motor deficit is rarely induced when resection of the frontal lobe is limited to only the SMA proper (corresponding roughly to Group A), the SMA proper and pre-SMA (corresponding roughly to Group B), or the SMA proper and premotor cortex (corresponding roughly to Group C), insofar as the primary motor cortex is preserved. Disturbance in fine movements of the upper extremity is frequently induced for the long term when wide areas of the SMA proper, pre-SMA as well as premotor cortex are resected altogether (corresponding roughly to Group D).