Takafumi Nagaoka

Thalamic deep brain stimulation for writer's cramp

OBJECT Writers 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 writers 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 writers cramp. METHODS The authors applied thalamic DBS in five patients with writers cramp. The inclusion criteria for the DBS trial in this disorder were a diagnosis of idiopathic writers 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 writers cramp were improved in all five cases. Postoperatively all preoperative scale scores indicating the seriousness of the writers 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 writers cramp by thalamic DBS. Insofar as they are aware, this is the first series in which writers cramp has been treated with DBS. Thalamic stimulation appears to be a safe and valuable therapeutic option for writers cramp.

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.

Brain-computer interface using near-infrared spectroscopy for rehabilitation

This study proposes a new method for detecting brain activity level for brain-computer interface (BCI) using a near-infrared spectroscopy (NIRS) which is applicable for rehabilitation. NIRS detects the radiated near-infrared rays, and measures relative variations of oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb) based on those absorbencies. The proposed method detects the brain activity level using oxy-Hb and the differential value of oxy-Hb. Results with grasping task show that the proposed method is effective for the detecting of brain activity level.

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 [18F]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 Parkinsons disease patients (N = 8).

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 andConclusion: The effectiveness of chronic thalamic DBS in this patient supports the concept of involvement of the thalamus in postperinatal anoxic myoclonus.

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.

Impairment of motor function after frontal lobe resection with preservation of the primary motor cortex

Abstract Clinical course and characteristics of the motor deficits were investigated in patients who underwent surgical resection of the frontal lobe for tumorous lesions. The extent of resection was classified into four groups. In Group A, resection was limited within the area above the superior frontal sulcus and posterior to a line vertical to the AC-PC line at the AC (VCA line). Resection was extended anterior to the VCA line in Group B or below the superior frontal sulcus in Group C. In Group D, resection was extended to both of these two boundaries. In results, 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 all together (corresponding roughly to Group D).

S28-3 D-wave monitoring in brain tumor surgery

through: (1) Somatosensory evoked potential phase reversal technique; (2) DCS with a short train of 5 7 monopolar stimuli (0.5ms duration, ISI 4.1, intensity up to 20mA) at 1 2Hz. To monitor motor pathways during tumor removal, MEPs are recorded from controlateral limb muscles after either DCS and/or transcranial electrical stimulation. When approaching tumor borders, MEP monitoring is combined with periodical direct subcortical stimulation (DSS) to localize the corticospinal tract (CT) and guide resection.A more than 75% drop in transcranial MEP amplitude at the end of surgery, and a DSS thresholds lower than 3 4mA are associated to post-operative neurological worsening. However these two neurophysiological warning signs are not significantly related and do not necessarily identify the same patients, suggesting that continuous MEP monitoring and periodical subcortical mapping should be combined to minimize risks. Recently, thanks to the introduction of diffusion tensor imaging and neuronavigation, there has been an increasing interest for the correlation of fiber tractography with subcortical stimulation. This work is providing some degree of reliability in the assessment of subcortical current spreading. Preliminary data suggest that 1mA = 1mm may be an acceptable practical parameter to judge on the distance from the CT, when using subcortical mapping.

72. Neuronal activity of the globus pallidus in dystonia

To test the effect of motor imagery as compared to voluntary muscle contraction on the excitability of the anterior horn cells, we studied F-wave persistence and amplitude, monitoring the force by a transducer. F-waves were recorded from the first dorsal interosseus muscle at rest and under a battery of motor tasks which comprised mental imagery and mild to moderate abduction of the index finger in 10 increments up to 30% of the maximal force. During each step lasting for 20 s, 20 stimuli were applied to the ulnar nerve at the wrist at the rate of one per second. In 12 healthy subjects, F-wave persistence (mean ± SD) significantly (p < 0.05) increased from 32.5 ± 11.9% at rest to 58.3 ± 15.2% during motor imagery and to 87–91% during voluntary contraction. Similarly, F-wave amplitude significantly (p < 0.05) increased from 41.3 ± 77.1 lV at rest to 91.2 ± 142.7 lV during motor imagery and to 183–274 lV during voluntary contraction. In contrast, F-wave latency changed little regardless of motor tasks. Motor imagery, though to a lesser degree than muscle contraction, effectively enhances the excitability of the anterior horn cells, thereby increasing F-wave persistence and amplitude above the baseline.

Intraoperative Monitoring of the Corticospinal MEP (D-wave) in Brain Tumor Surgery

The recently reported procedure of awake surgery [1,2], which employs local anesthesia and intravenous injection of propofol and lenitive drugs, can guarantee a preserved motor function in cases of tumor resection around the motor cortex and subcortical motor tract. It is well known that the disturbed motor function which is caused by injury of the supplementary motor cortex [3] or premotor cortex [4] can undergo complete recovery within several weeks. Awake surgery is a very useful method and can secure a preserved motor function if the motor function is intact during the operation; however, it is unable to achieve maximal tumor resection which involves transient motor disturbance and subsequent functional recovery.