Comparison of the Interference Effects on Somatosensory Evoked Potential from Tonic, Burst, and High-dose Spinal Cord Stimulations.

Spinal cord stimulations have been used widely to treat intractable neuropathic pain. The conventional spinal cord stimulation paradigm, the "tonic" type, suppresses excessive activation of wide dynamic range neurons in the dorsal horn via the collateral branch from the dorsal column. Therefore, preserved dorsal column function is an important prerequisite for tonic spinal cord stimulations. A tonic spinal cord stimulation requires eliciting paresthesia in the painful area due to stimulation of the dorsal column and dorsal root. Recent spinal cord stimulation paradigms, including burst and high-dose, are set below the paresthesia threshold and are proposed to have different pain reduction mechanisms. We conducted an interference study of these different stimulation paradigms on the somatosensory evoked potential (SEP) to investigate differences in the sites of action between tonic and new spinal cord stimulations. We recorded posterior tibial nerve-stimulated SEP in seven patients with neuropathic pain during tonic, burst, and high-dose stimulations. The total electrical energy delivered was calculated during SEP-spinal cord stimulation interference studies. High-dose stimulations could not reduce the SEP amplitude despite higher energy delivery than tonic stimulation. Burst stimulation with an energy similar to the tonic stimulation could not reduce SEP amplitude as tonic stimulation. The study results suggested different sites of action and effects on the spinal cord between the conventional tonic and burst or high-dose spinal cord stimulations.

Effects of Medications and Subthalamic Nucleus-Deep Brain Stimulation on the Cutaneous Silent Period in Patients With Parkinson's Disease.

OBJECTIVES: We sought to evaluate whether the cutaneous silent period (CSP) could be an electrophysiological indicator reflective of the effects of therapy for Parkinson's disease (PD), including anti-PD medications or deep brain stimulation (DBS). MATERIAL AND METHODS: We recorded the CSP in 43 patients with PD prior to and following the administration of medication during a pre-DBS evaluation (30 cases) and the "on" and "off" states of subthalamic nucleus DBS (13 cases). The CSP was elicited from the abductor pollicis brevis muscle by an electrical stimulation of the index finger that was 2, 4, and 15 times stronger than the sensory threshold (ST). We measured changes in latencies, including the onset, duration, and end of CSP, and waveform scores from 0 to 3. The correlation between the CSP score and unified PD rating score part III (UPDRS-III) also was assessed. RESULTS: The onset latency and duration of CSP were significantly different between high- (15ST) and low-strength stimulations (2ST and 4ST). However, there were no significant latency changes (onset, duration, end of CSP) before and after receiving medication, or during the on and off state of the DBS. Anti-PD medications substantially increased the CSP waveform score only in the 4ST state. However, the waveform score significantly increased in all stimuli states during the DBS-on state. Both medication and the DBS-on state decreased the UPDRS-III. Nevertheless, there was no statistically significant correlation between the UPDRS-III and CSP waveform scores. CONCLUSION: Different onset latencies and the duration of CSP between low- and high-strength stimuli support the hypotheses proposing two different reflex pathways. Despite being independent from the UPDRS-III, the CSP may be an electrophysiological indicator reflective of the changes in inhibitory activity to the spinal α-motoneuron in response to anti-PD medications and DBS.

Development of Quality of Life Questionnaire for Patients with Parkinson's Disease Undergoing STN-DBS.

In device-aided therapy (DAT) for Parkinson's disease (PD), factors such as device-related adverse effects, psychological and lifestyle changes, and specific disease progression can affect the quality of life (QoL) of patients with advanced PD. However, there is no existing QoL scale that includes the effects of therapeutic devices. From a semi-structured interview with patients with PD undergoing deep brain stimulation (DBS), we extracted the content of utterances that were thought to affect the QoL and created a draft questionnaire consisting of 113 items. This questionnaire was administered to 54 other patients undergoing DBS, whose data were examined for reliability and validity by factor analysis, and finally, a 24-item PD QoL questionnaire for patients on DAT (PDQ-DAT) was developed. Presently, the PDQ-DAT is the only scale that can assess the QoL of patients on DAT, including the influence treatment devices have on them. In the future, it might be used to help in shared decision-making in medicine by incorporating the patient's sense of burden and values in the selection of treatment methods.

Diplopia associated with loop routing in deep brain stimulation: illustrative case.

BACKGROUND: Deep brain stimulation (DBS) is a powerful surgical option for drug-resistant movement disorders; however, electromagnetic interference (EMI) from external sources poses a potential risk for implanted electronics. OBSERVATIONS: A 61-year-old woman with Parkinson's disease originally had two implantable pulse generators (IPGs) for bilateral subthalamic DBS, which were then replaced with one dual-channel IPG routed in a loop. After the replacement surgery, with the same DBS programming as before the IPG replacement (bipolar setting for right, unipolar setting for left), the patient began to complain of transient paroxysmal diplopia. After multiple attempts to adjust the stimulation parameters, the diplopia was resolved by changing the left unipolar setting to a bipolar setting. At the authors' institution, before the present case, four other patients had undergone IPG replacement with loop routing. None of these previous patients complained of diplopia; however, two of the four presented with diplopia in an experimental unipolar setting. LESSONS: Clinicians should be aware that loop-routed circuits may generate distortion of the stimulus field in DBS, even in the absence of external EMI sources.

Secondary Worsening Following DYT1 Dystonia Deep Brain Stimulation: A Multi-country Cohort.

Objective: To reveal clinical characteristics of suboptimal responses to deep brain stimulation (DBS) in a multi-country DYT1 dystonia cohort. Methods: In this multi-country multi-center retrospective study, we analyzed the clinical data of DYT1 patients who experienced suboptimal responses to DBS defined as <30% improvement in dystonia scales at the last follow-up compared with baseline. We used a literature-driven historical cohort of 112 DYT1 patients for comparison. Results: Approximately 8% of our study cohort (11 out of 132) experienced suboptimal responses to DBS. Compared with the historical cohort, the multi-country cohort with suboptimal responses had a significantly younger age at onset (mean, 7.0 vs. 8.4 years; p = 0.025) and younger age at DBS (mean, 12.0 vs. 18.6 years; p = 0.019). Additionally, cranial involvement was more common in the multi-country cohort (before DBS, 64% vs. 45%, p = 0.074; before or after DBS, 91% vs. 47%, p = 0.001). Mean motor improvement at the last follow-up from baseline were 0% and 66% for the multi-country and historical cohorts, respectively. All 11 patients of the multi-country cohort had generalization of dystonia within 2.5 years after disease onset. All patients experienced dystonia improvement of >30% postoperatively; however, secondary worsening of dystonia commenced between 6 months and 3 years following DBS. The improvement at the last follow-up was less than 30% despite optimally-placed leads, a trial of multiple programming settings, and additional DBS surgeries in all patients. The on-/off-stimulation comparison at the long-term follow-up demonstrated beneficial effects of DBS despite missing the threshold of 30% improvement over baseline. Conclusion: Approximately 8% of patients represent a more aggressive phenotype of DYT1 dystonia characterized by younger age at onset, faster disease progression, and cranial involvement, which seems to be associated with long-term suboptimal responses to DBS (e.g., secondary worsening). This information could be useful for both clinicians and patients in clinical decision making and patient counseling before and following DBS implantations. Patients with this phenotype may have different neuroplasticity, neurogenetics, or possibly distinct neurophysiology.

The effects of chronic subthalamic stimulation on nonmotor symptoms in advanced Parkinson's disease, revealed by an online questionnaire program.

BACKGROUND: This study was designed to detect and assess the frequency and severity of nonmotor symptoms (NMSs) in advanced Parkinson's disease (PD) and to investigate the effects of subthalamic nucleus deep brain stimulation (STN-DBS) on NMSs. METHODS: We developed an online PC-based questionnaire program to assess NMSs in PD. Twenty-six PD patients who underwent bilateral STN-DBS were assessed. The NMS questionnaire consisted of 54 NMSs in three categories, based on Witjas et al. (2002). For each NMS, the patients were asked whether or not it was present, whether or not the fluctuating manifestations correlated with the timing of levodopa-induced motor fluctuations, and how severe the NMS was. Patients were assessed by this system before surgery and at the follow-up visit, 3 to 6 months after surgery. At the postoperative assessment, patients were also assessed on preoperative NMSs using recall. RESULTS: The most frequent preoperative NMSs were constipation and visual disorders, while the most frequent postoperative NMSs were difficulty in memorizing and pollakiuria. The ranking of most frequent NMSs changed from before to after surgery. NMSs of drenching sweats, dysphagia, and constipation were significantly ameliorated, while NMSs of dyspnea and slowness of thinking were significantly deteriorated after surgery. The preoperative assessment by postoperative recall gave very different results from that of the preoperative assessment. CONCLUSION: An online questionnaire system to assess NMSs in patients with advanced PD suggested that STN-DBS might influence the frequencies of some kinds of NMSs.

Predictive Factors of Antiparkinsonian Drug Reduction after Subthalamic Stimulation for Parkinson's Disease.

Subthalamic nucleus deep brain stimulation (STN-DBS) improves motor symptoms in individuals with advanced Parkinson's disease (PD) and enables physicians to reduce doses of antiparkinsonian drugs. We investigated possible predictive factors for the successful reduction of antiparkinsonian drug dosage after STN-DBS. We evaluated 33 PD patients who underwent bilateral STN-DBS. We assessed rates of reduction of the levodopa-equivalent daily dose (LEDD) and levodopa daily dose (LDD) by comparing drug doses before vs. 6-months post-surgery. We used correlation coefficients to measure the strength of the relationships between LEDD and LDD reduction rates and preoperative factors including age, disease duration, preoperative LEDD and LDD, unified Parkinson's Disease Rating Scale part-II and -III, levodopa response rate, Mini-Mental State Examination score, dyskinesia score, Hamilton Rating Scale for depression, and the number of non-motor symptoms. The average LEDD and LDD reduction rates were 61.0% and 70.4%, respectively. Of the variables assessed, only the number of psychiatric/cognitive symptoms was significantly correlated with the LEDD reduction rate. No other preoperative factors were correlated with the LEDD or LDD reduction rate. A wide range of preoperative psychiatric and cognitive symptoms may predict the successful reduction of antiparkinsonian drugs after STN-DBS.

Fast modified Self-organizing Deformable Model: Geometrical feature-preserving mapping of organ models onto target surfaces with various shapes and topologies.

BACKGROUND AND OBJECTIVE: This paper proposes a new method for mapping surface models of human organs onto target surfaces with the same genus as the organs. METHODS: In the proposed method, called modified Self-organizing Deformable Model (mSDM), the mapping problem is formulated as the minimization of an objective function which is defined as the weighted linear combination of four energy functions: model fitness, foldover-free, landmark mapping accuracy, and geometrical feature preservation. Further, we extend mSDM to speed up its processes, and call it Fast mSDM. RESULTS: From the mapping results of various organ models with different number of holes, it is observed that Fast mSDM can map the organ models onto their target surfaces efficiently and stably without foldovers while preserving geometrical features. CONCLUSIONS: Fast mSDM can map the organ model onto the target surface efficiently and stably, and is applicable to medical applications including Statistical Shape Model.

[Early Experience with the VerciseTM DBS System in the Treatment of Dystonic Tremor].

Six cases of dystonic tremor were treated with the VerciseTM deep brain stimulation(DBS)system, which has the multiple independent current control(MICC)technology. The mean preoperative score of Burke-Fahn-Marsden dystonia rating scale was 16.2±9.4, which was reduced to 6.1±4.6 at 5 months postoperatively. A 65-year-old male presented an intractable dystonic tremor of the jaw, neck, and shoulders due to tardive syndrome. He experienced the successful tremor relief after unipolar DBS in the globus pallidus internus(GPi)with VerciseTM but complained of dysarthria. Steering the current ventrally induced nausea without alleviating dysarthria, while steering the current dorsally alleviated dysarthria but a further dorsal current induced mandibular dyskinesia. The current steering with MICC enabled the simulation field in GPi with successful balance, maximizing tremor suppression, and minimizing the adverse effects. In a second case, 61-year-old male in whom cervical dystonia with rotatory tremor had been successfully treated with interleaving stimulation of GPi-DBS had needed to repeat the replacement of a non-rechargeable pulse generator in only 15-month interval. After the substitution of VerciseTM, the interleaving stimulation of 9.5mA in total was replaced by 8.5mA with the current steering of MICC, while the patient's symptomatic control was unchanged. The microlesion effects after lead implantation are unclear and therapeutic effects are often delayed in cases of dystonia;therefore, the submaximal stimulation intensities must be frequently applied in the early phase following the implantation of DBS. A fine current steering of VerciseTM DBS is very useful in both, the early and late phases of GPi-DBS for dystonic syndrome.

Estimation of brain internal structures by deforming brain atlas using finite element method.

This paper presents a method for estimating the internal structures of a patient brain by deforming a standard brain atlas. Conventional deformation methods need several landmarks from the brain surface contour to fit the atlas to the patient brain shape. However, since the number and shapes of small sulci on the brain surface are different from each other, the determination of the accurate correspondence between small sulcus is difficult for experienced neurosurgeons. Moreover, the relationship between the surface shape and internal structure of the brain is unclear. Therefore, even if the deformed atlas is fitted to the patient brain shape exactly, the use of the deformed atlas does not always guarantee the reliable estimation of the internal structure of the patient brain. To solve these problems, we propose a new method for estimate the internal structure of a patient brain by the finite element method (FEM). In the deformation, our method select the landmarks from the contours of both the brain surface and the detectable internal structures from MR images.

Tolerance of early pallidal stimulation in pediatric generalized dystonia.

The authors report on 2 cases of pediatric generalized dystonia with a DYT1 mutation; the patients, an 11-year-old girl and a 9-year-old boy, underwent chronic, pallidal deep brain stimulation (DBS) of the globus pallidus internus (GPi). The dystonic postures in both cases showed dramatic improvements with pallidal DBS, but each patient's symptoms gradually recurred within a year, irrespective of exhaustive readjustments of the stimulation settings. After the recurrence of the dystonic symptoms, the DBS leads were replaced within the GPi in one patient (Case 1) and additional DBS leads were implanted into the bilateral subthalamic nuclei in the other patient (Case 2). Neither measure produced any further clinical benefit, and the patient in Case 2 died of status dystonicus 2 days after reoperation. These findings suggest that early pallidal DBS for pediatric dystonia is indeed effective, although there are some cases in which its therapeutic effect is lost. One possible reason may be the ability of the preadolescent brain to tolerate chronic electrical stimuli during the active maturation process.

Short circuit in deep brain stimulation.

OBJECT: The authors undertook this study to investigate the incidence, cause, and clinical influence of short circuits in patients treated with deep brain stimulation (DBS). METHODS: After the incidental identification of a short circuit during routine follow-up, the authors initiated a policy at their institution of routinely evaluating both therapeutic impedance and system impendence at every outpatient DBS follow-up visit, irrespective of the presence of symptoms suggesting possible system malfunction. This study represents a report of their findings after 1 year of this policy. RESULTS: Implanted DBS leads exhibiting short circuits were identified in 7 patients (8.9% of the patients seen for outpatient follow-up examinations during the 12-month study period). The mean duration from DBS lead implantation to the discovery of the short circuit was 64.7 months. The symptoms revealing short circuits included the wearing off of therapeutic effect, apraxia of eyelid opening, or dysarthria in 6 patients with Parkinson disease (PD), and dystonia deterioration in 1 patient with generalized dystonia. All DBS leads with short circuits had been anchored to the cranium using titanium miniplates. Altering electrode settings resulted in clinical improvement in the 2 PD cases in which patients had specific symptoms of short circuits (2.5%) but not in the other 4 cases. The patient with dystonia underwent repositioning and replacement of a lead because the previous lead was located too anteriorly, but did not experience symptom improvement. CONCLUSIONS: In contrast to the sudden loss of clinical efficacy of DBS caused by an open circuit, short circuits may arise due to a gradual decrease in impedance, causing the insidious development of neurological symptoms via limited or extended potential fields as well as shortened battery longevity. The incidence of short circuits in DBS may be higher than previously thought, especially in cases in which DBS leads are anchored with miniplates. The circuit impedance of DBS should be routinely checked, even after a long history of DBS therapy, especially in cases of miniplate anchoring.

A simple but accurate method for histological reconstruction of the large-sized brain tissue of the human that is applicable to construction of digitized brain database.

Research on the human brain has undoubted significance, but our knowledge on its detailed morphology is still limited. We have developed a simple method for reconstruction of large-sized brain tissues of the human. Fixed brains were cut into blocks (maximum size 7 cm x 7 cm x 1 cm), embedded and postfixed in gelatin just one overnight before obtaining complete serial sections with a vibrating microtome. Quality of stained materials was sufficient to create three-dimensional histological maps, where digital reconstructions from adjoining blocks could be accurately combined. The present method will facilitate both direct examination of the human brain and construction of its histological database.

Double lumbosacral lipomas of the dorsal and filar types associated with OEIS complex: case report.

A female baby was born at 37 weeks and 6 days gestation by vaginal delivery with omphalocele, exstrophy of the cloaca, and imperforate anus, indicating the presence of OEIS complex, a rare combination of defects consisting of omphalocele (O), exstrophy of the cloaca (E), imperforate anus (I), and spinal deformity (S), associated with lumbosacral lipoma. The most common associated spinal deformity is terminal myelocystocele, and spinal lipoma is rare. Constructive interference in steady-state magnetic resonance imaging clearly revealed double lipomas, a dorsal-type lipoma, located dorsal to the low-lying conus medullaris, and a filar-type lipoma, revealed by a thickened and fatty filum terminale. After recovery from abdominogenital repairs, debulking of the dorsal-type lipoma and untethering of the spinal cord by sectioning of the filar-type lipoma were performed at the age of 14 months. Neurosurgical treatment for occult spinal dysraphism should be undertaken after recovery from the initial series of major abdominogenital procedures.

Spectral analysis of field potential recordings by deep brain stimulation electrode for localization of subthalamic nucleus in patients with Parkinson's disease.

AIMS: Spectral analysis of local field potential (LFP) recorded by deep brain stimulation (DBS) electrode around the subthalamic nucleus (STN) in patients with Parkinson's disease was performed. METHODS: The borders of the STN were determined by microelectrode recording. The most eligible trajectory for the sensorimotor area of the STN was used for LFP recording while advancing the DBS electrode. RESULTS: The low-frequency LFP power (theta- to beta-band) increased from a few millimeters above the dorsal border of the STN defined by microelectrode recording; however, the low-frequency power kept the same level beyond the ventral border of the STN. Only high beta-power showed close correlation to the dorsal and ventral borders of the STN. CONCLUSIONS: A spectral power analysis of LFP recording by DBS electrode helps with the final confirmation of the dorsal and ventral borders of the STN of Parkinson's disease in DBS implantation surgery.

[Intracerebral hemorrhage during multi-track microrecording of deep brain stimulation surgery: a report of three cases].

We described three cases with hemorrhagic complication during simultaneous multi-track microelectrode recording (MER) for stereotactic implantation of a subthalamic nucleus electrode. Although preoperative planning with gadolinium-enhanced T1-weighted MR images is recommended to prevent the occurrence of intracerebral hemorrhage, it should be noted that the danger from cerebral vasculatures is still underestimated. Multiple nonspecific white matter hyperintensities and asymptomatic lacunar infarcts may be suspected as potential risk factors, so, it is suggested that the number of MER penetrations should be restricted in such cases.

Subthalamic nucleus stimulation does not cause deterioration of preexisting hallucinations in Parkinson's disease patients.

BACKGROUND: Among the neuropsychiatric symptoms in Parkinson's disease (PD) patients, hallucination can result from the disease itself or medical treatment. Hallucination associated with subthalamic nucleus stimulation (STN-DBS) has been reported; however, it is still unclear whether PD patients with a history of hallucination are appropriate candidates for STN-DBS or not. AIMS: We investigated the effect of STN-DBS on preexisting hallucination associated with advanced PD. METHODS: Eighteen STN-DBS patients were investigated retrospectively. The severity of hallucination was assessed by the thought disorder score on the Unified Parkinson's Disease Rating Scale (UPDRS, part 1-item 2) in the patients' interviews; the score 6 months after the initiation of STN-DBS was compared with the highest score throughout the preoperative history and the score 2 weeks before surgery. RESULTS: Hoehn-Yahr stage and motor score (UPDRS part 3) were significantly improved following STN-DBS. Six months after the initiation of STN-DBS, the severity of hallucination, assessed by thought disorder score, did not increase, but rather decreased compared with the preoperative level (p < 0.05 by McNemar's test). The daily levodopa equivalent dose was increased in 2 patients without the development of hallucination. On the other hand, anti-parkinsonian drugs were totally withdrawn in 1 patient, but without improvement of hallucination. CONCLUSIONS: Our findings indicate that STN-DBS surgery does not always lead to deterioration of preexisting hallucination in PD. In advanced PD, hallucination involves a multifactorial pathogenesis and a history of hallucination is not a contraindication to STN-DBS surgery.

Detailed anatomy of intracranial venous anomalies associated with atretic parietal cephaloceles revealed by high-resolution 3D-CISS and high-field T2-weighted reversed MR images.

PURPOSE: The advancement of magnetic resonance (MR) imaging technology has revealed that intracranial venous anomalies, such as vertical embryonic positioning of the straight sinus (VEP of SS), are associated with atretic parietal cephaloceles. However, the precise anatomical relationships among the venous anomalies, superior sagittal sinus (SSS), cistern, and cephalocele have not been demonstrated. We compared the imaging features of conventional MR images and high-resolution 3-dimensional (3-D) MR images, such as Fourier-transformation-constructive interference in steady-state (CISS) images and T2-weighted reversed (T2R) images obtained on a 3-T MR machine. METHODS: Three patients ranging in age from 1 to 18 years, with midline subscalp lesions, participated in this study. In two cases, the lesions were surgically excised and subjected to pathological examination. RESULTS: In two children, 3-D MR images more clearly demonstrated anomalous veins, including bilateral internal cerebral veins, the great vein of Galen and the vertical position of the straight sinus in the falx, extending superiorly within the CSF tract in the posterior interhemispheric fissure. While the vertical straight sinus drained into the SSS, the CSF tract maintained a position posterior to the anomalous veins, ran through the SSS and extended to the skull defect. In one patient, ascending positioning of the anomalous vein from the inferior sagittal sinus to the SSS in the CSF space was observed; this could not be depicted on conventional MR images. CONCLUSION: Detailed findings of the venous anomalies on 3-D MR images provide clues to the diagnosis of atretic cephalocele.

Coexistence of a human tail and congenital dermal sinus associated with lumbosacral lipoma.

CASE REPORT: We present a female baby with a human tail associated with congenital dermal sinus (CDS) at the caudal site of the tail. Magnetic resonance (MR) images with constructive interference in steady-state (CISS) sequencing clearly demonstrated a lumbosacral lipoma of caudal type, contiguous with the dermal sinus tract and not with the human tail. At 3 months old, the tail was surgically removed. The dermal sinus tract and contiguous lipoma were also resected, and untethering of the spinal cord was performed. Although both the human tail and CDS are frequently associated with spina bifida occulta, coexistence of the tail and CDS is exceedingly rare. CISS-MRI is useful for demonstrating the precise anatomical relationship between these complicated pathologies.

Medial temporal lobe epilepsy associated with misplacement of a ventricular shunting catheter.

We report the case of a 35-year-old woman who developed right medial temporal lobe epilepsy associated with misplacement of a ventricular shunting catheter in the apex of the right temporal lobe. At 8 years of age, the patient had undergone total removal of a cerebellar astrocytoma and placement of a Torkildsen's ventriculo-cisternal shunt for obstructive hydrocephalus. Although the postoperative course was uneventful, she developed medically intractable psychomotor seizures with secondary generalization at 24 years of age. CT revealed that the tip of the shunting catheter was misplaced in the apex of the right temporal lobe, through the posterior and inferior horn of the right lateral ventricle. Intraoperative electrocorticography revealed frequent paroxysmal activity in the hippocampus, so hippocampectomy as well as removal of the shunting catheter was performed. Postoperatively, the patient became seizure-free, and pathological examination revealed hippocampal sclerosis.