Chikashi Fukaya

Evoked-cerebral blood oxygenation changes in false-negative activations in BOLD contrast functional MRI of patients with brain tumors.

Blood oxygenation level dependent contrast functional MRI (BOLD-fMRI) has been used to define the functional cortices of the brain in preoperative planning for tumor removal. However, some studies have demonstrated false-negative activations in such patients. We compared the evoked-cerebral blood oxygenation (CBO) changes measured by near-infrared spectroscopy (NIRS) and activation mapping of BOLD-fMRI in 12 patients with brain tumors who had no paresis of the upper extremities. On the nonlesion side, NIRS demonstrated a decrease in deoxyhemoglobin (Deoxy-Hb) with increases in oxyhemoglobin (Oxy-Hb) and total hemoglobin (Total-Hb) during a contralateral hand grasping task in the primary sensorimotor cortex (PSMC) of all patients. On the lesion side, NIRS revealed a decrease in Deoxy-Hb in five patients (Deoxy-decrease group), and an increase in Deoxy-Hb in seven patients (Deoxy-increase group); the Oxy-Hb and Total-Hb were increased during activation in both groups, indicating the occurrence of rCBF increases in response to neuronal activation. BOLD-fMRI demonstrated clear activation areas in the PSMC on the nonlesion side of all patients and on the lesion side of the Deoxy-decrease group. However, in the Deoxy-increase group, BOLD-fMRI revealed only a small activation area or no activation on the lesion side. Intraoperative brain mapping identified the PSMC on the lesion side that was not demonstrated by BOLD-fMRI. The false-negative activations might have been caused by the atypical evoked-CBO changes (i.e. increases in Deoxy-Hb) and the software employed to calculate the activation maps, which does not regard an increase of Deoxy-Hb (i.e., a decrease in BOLD-fMRI signal) as neuronal activation.

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.

Motor Cortex Stimulation for Phantom Limb Pain: Comprehensive Therapy with Spinal Cord and Thalamic Stimulation

The effects of spinal cord stimulation (SCS), deep brain stimulation (DBS) of the thalamic nucleus ventralis caudalis (VC) and motor cortex stimulation (MCS) were analyzed in 19 patients with phantom limb pain. All of the patients underwent SCS and, if the SCS failed to reduce the pain, the patients were considered for DBS and/or MCS. Satisfactory pain control for the long-term was achieved in 6 of 19 (32%) by SCS, 6 of 10 (60%) by DBS and 1 (20%) of 5 by MCS. SCS and DBS of the VC sometimes produced a dramatic effect on the pain, leading to a long pain-free interval and infrequent use of stimulation. The effects of both DBS of the VC and MCS were tested in four. One patient of them reported better pain control by MCS than by DBS, whereas two reported the opposite results. There is no evidence at present for an advantage of MCS over SCS and DBS of the VC in controlling phantom limb pain.

Motor Cortex Stimulation for Post-Stroke Pain: Comparison of Spinal Cord and Thalamic Stimulation

We analyzed the effects of spinal cord stimulation (SCS), deep brain stimulation (DBS) of the thalamic nucleus ventralis caudalis (VC) and motor cortex stimulation (MCS) in 45 patients with post-stroke pain. Satisfactory pain control was obtained more frequently as the stimulation site was moved to higher levels (7% by SCS, 25% by DBS and 48% by MCS). A painful sensation was sometimes produced by stimulation of the VC as well as the post-central, pre-central and pre-frontal cortices. Such a sensation occurred less frequently as the stimulation site was moved to higher levels (50% at the VC, 39% at the post-central cortex, 6% at the pre-central cortex and 3% at the pre-frontal cortex). These findings imply that abnormal processing of nociceptive information develops at the level of deafferentation and spreads to higher levels to a varying extent. This may be one of the reasons why satisfactory pain control was obtained more frequently as the stimulation site was moved to higher levels.

Deep brain stimulation for the treatment of vegetative state

One hundred and seven patients in vegetative state (VS) were evaluated neurologically and electrophysiologically over 3 months (90 days) after the onset of brain injury. Among these patients, 21 were treated with deep brain stimulation (DBS). The stimulation sites were the mesencephalic reticular formation (two patients) and centromedian–parafascicularis nucleus complex (19 cases). Eight of the patients recovered from VS and were able to obey verbal commands at 13 and 10 months in the case of head trauma and at 19, 14, 13, 12, 12 and 8 months in the case of vascular disease after comatose brain injury, and no patients without DBS recovered from VS spontaneously within 24 months after brain injury. The eight patients who recovered from VS showed desynchronization on continuous EEG frequency analysis. The Vth wave of the auditory brainstem response and N20 of the somatosensory evoked potential could be recorded, although with a prolonged latency, and the pain‐related P250 was recorded with an amplitude of > 7 μV. Sixteen (14.9%) of the 107 VS patients satisfied these criteria in our electrophysiological evaluation, 10 of whom were treated with DBS and six of whom were not treated with DBS. In these 16 patients, the recovery rate from VS was different between the DBS therapy group and the no DBS therapy group (P < 0.01, Fisher’s exact probability test) These findings indicate that DBS may be useful for the recovery of patients from VS if the candidates are selected on the basis of electrophysiological criteria.

DBS therapy for the vegetative state and minimally conscious state

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.

Control of poststroke involuntary and voluntary movement disorders with deep brain or epidural cortical stimulation.

The effects of deep brain or epidural cortical stimulation on poststroke involuntary and voluntary movement disorders were analyzed in a total of 64 patients. Among them, 22 patients underwent either deep brain or epidural cortical stimulation in order to control their poststroke involuntary movements. The remaining 42 underwent epidural cortical stimulation for the purpose of controlling their poststroke pain. In the latter group of patients, we analyzed the changes in coexistent involuntary or voluntary movement disorders during stimulation for pain control. Stimulation of either the thalamic nucleus ventralis intermedius or the motor cortex proved to be useful in 13 (59%) of the patients who underwent deep brain or epidural cortical stimulation for control of poststroke involuntary movements. Satisfactory control was often achieved in patients with hemiballismus, hemichorea or resting tremor. In 8 (19%) of the patients who underwent epidural cortical stimulation for pain control, stimulation of the motor cortex improved motor performance which had been impaired in association with hemiparesis. Such an effect was independent of pain control and apparently resulted from an inhibition of their rigidity. We believe that these findings justify further clinical studies on deep brain or epidural cortical stimulation for the control of poststroke movement disorders.

Deep brain and motor cortex stimulation for post-stroke movement disorders and post-stroke pain

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 intermedius. 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.

Increase in focal concentration of deoxyhaemoglobin during neuronal activity in cerebral ischaemic patients

Background and Purpose: Blood oxygenation level dependent contrast functional magnetic resonance imaging (BOLD-fMRI) has been applied to functional mapping in brain disorders, based on the assumption that normal adults and patients with brain disorders exhibit similar evoked cerebral blood oxygenation (CBO) changes. This study compared evoked CBO changes measured by near infrared spectroscopy (NIRS) with the activation mapping obtained by BOLD-fMRI in patients with cerebral ischaemia. Methods: The study involved six normal adults and six patients with cerebral ischaemia. Hand grasping was performed as a motor task. All patients could perform the task similarly to the controls at the time of examination, but single photon emission computed tomography demonstrated low baseline cerebral blood flow and a decreased haemodynamic reserve in the primary sensorimotor cortex on the lesion side. Using NIRS, concentration changes of deoxyhaemoglobin (Deoxy-Hb), oxyhaemoglobin (Oxy-Hb), and total haemoglobin (Total-Hb) were measured in the primary sensorimotor cortex contralateral to the task. BOLD-fMRI signals were measured by 1.5 T magnetic resonance imaging using an echo-planar technique. Activation maps were calculated by statistical parametric mapping. Results: In the controls, Deoxy-Hb decreased in association with increases of Oxy-Hb and Total-Hb in the primary sensorimotor cortex during the task. However, in the patients, Deoxy-Hb increased significantly from baseline, while Oxy-Hb and Total-Hb also increased, indicating the presence of rCBF increases in response to neuronal activation. BOLD-fMRI demonstrated only limited activation areas in the primary sensorimotor cortex on the lesion side. Conclusion: The CBO changes in patients with cerebral ischaemia differed from those of normal adults; Deoxy-Hb was increased in activation areas of the patients. This implies that BOLD-fMRI may overlook activation areas in the patients unless both increases and decreases of signal are taken into consideration.

Intraoperative wake-up procedure with propofol and laryngeal mask for optimal excision of brain tumour in eloquent areas.

This is the first thesis describing a new technique for awake craniotomy using a laryngeal mask. Awake craniotomy with propofol infusion has become increasingly popular for the optimal excision of brain tumours located in eloquent areas. During awake craniotomy, tracheal intubation is not performed and propofol infusion is limited to within doses which render the patient just sedated. This asleep-awake procedure is occasionally associated with difficulty in controlling brain volume, especially in patients with a significant mass effect of their brain tumours, since sufficient sedation with propofol tends to cause hypercapnea. We report an intraoperative wake-up procedure employing a laryngeal mask, which enables general anaesthesia to be performed at a sufficient dose of propofol and with control of the brain volume under mechanically assisted ventilation. Before the beginning of cortical mapping, propofol infusion is completely terminated, so allowing the patient to wake up within 5-15 min. Following completion of the tumour excision, general anaesthesia is re-induced at a sufficient dose of propofol. The laryngeal mask can be temporarily removed and repositioned with ease, if necessary. In our experience, this technique is applicable for the optimal excision of brain tumours, especially in patients who are very obese or those who have very large lesions.