Pretreatment brain volumes can affect the effectiveness of deep brain stimulation in Parkinson's disease patients.

We aimed to assess whether brain volumes may affect the results of deep brain stimulation (DBS) in patients with Parkinson's disease (PD). Eighty-one consecutive patients with PD (male:female 40:41), treated with DBS between June 2012 and December 2017, were enrolled. Total and regional brain volumes were measured using automated brain volumetry (NeuroQuant). The Unified Parkinson Disease Rating Scale motor score quotient was used to assess changes in clinical outcome and compare the preoperative regional brain volume in patients categorized into the higher motor improvement and lower motor improvement groups based on changes in the postoperative scores. The study groups showed significant volume differences in multiple brain areas. In the higher motor improvement group, the anterior cingulate and right thalamus showed high volumes after false discovery rate (FDR) correction. In the lower motor improvement group, the left caudate, paracentral, right primary sensory and left primary motor cortex showed high volume, but no area showed high volumes after FDR correction. Our data suggest that the effectiveness of DBS in patients with PD may be affected by decreased brain volume in different areas, including the cingulate gyrus and thalamus. Preoperative volumetry could help predict outcomes in patients with PD undergoing DBS.

Deep Learning-Based Deep Brain Stimulation Targeting and Clinical Applications.

BACKGROUND: The purpose of the present study was to evaluate deep learning-based image-guided surgical planning for deep brain stimulation (DBS). We developed deep learning semantic segmentation-based DBS targeting and prospectively applied the method clinically. METHODS: T2∗ fast gradient-echo images from 102 patients were used for training and validation. Manually drawn ground truth information was prepared for the subthalamic and red nuclei with an axial cut ∼4 mm below the anterior-posterior commissure line. A fully convolutional neural network (FCN-VGG-16) was used to ensure margin identification by semantic segmentation. Image contrast augmentation was performed nine times. Up to 102 original images and 918 augmented images were used for training and validation. The accuracy of semantic segmentation was measured in terms of mean accuracy and mean intersection over the union. Targets were calculated based on their relative distance from these segmented anatomical structures considering the Bejjani target. RESULTS: Mean accuracies and mean intersection over the union values were high: 0.904 and 0.813, respectively, for the 62 training images, and 0.911 and 0.821, respectively, for the 558 augmented training images when 360 augmented validation images were used. The Dice coefficient converted from the intersection over the union was 0.902 when 720 training and 198 validation images were used. Semantic segmentation was adaptive to high anatomical variations in size, shape, and asymmetry. For clinical application, two patients were assessed: one with essential tremor and another with bradykinesia and gait disturbance due to Parkinson's disease. Both improved without complications after surgery, and microelectrode recordings showed subthalamic nuclei signals in the latter patient. CONCLUSION: The accuracy of deep learning-based semantic segmentation may surpass that of previous methods. DBS targeting and its clinical application were made possible using accurate deep learning-based semantic segmentation, which is adaptive to anatomical variations.

Magnetic Resonance Imaging Distortion and Targeting Errors from Strong Rare Earth Metal Magnetic Dental Implant Requiring Revision.

Recently, the use of magnetic dental implants has been re-popularized with the introduction of strong rare earth metal, for example, neodymium, magnets. Unrecognized magnetic dental implants can cause critical magnetic resonance image distortions. We report a case involving surgical failure caused by a magnetic dental implant. A 62-year-old man underwent deep brain stimulation for medically insufficiently controlled Parkinson"s disease. Stereotactic magnetic resonance imaging performed for the first deep brain stimulation showed that the overdenture was removed. However, a dental implant remained and contained a neodymium magnet, which was unrecognized at the time of imaging; the magnet caused localized non-linear distortions that were the largest around the dental magnets. In the magnetic field, the subthalamic area was distorted by a 4.6 mm right shift and counter clockwise rotation. However, distortions were visually subtle in the operation field and small for distant stereotactic markers, with approximately 1-2 mm distortions. The surgeon considered the distortion to be normal asymmetry or variation. Stereotactic marker distortion was calculated to be in the acceptable range in the surgical planning software. Targeting errors, approximately 5 mm on the right side and 2 mm on the left side, occurred postoperatively. Both leads were revised after the removal of dental magnets. Dental magnets may cause surgical failures and should be checked and removed before stereotactic surgery. Our findings should be considered when reviewing surgical precautions and making distortion-detection algorithm improvements.

Systematic Stereotactic Error Reduction Using a Calibration Technique in Single-Brain-Pass and Multitrack Deep Brain Stimulations.

BACKGROUND: A calibration technique that shifts the frame coordinates from the intended coordinates to correct a systematic stereotactic error has been reported for single-brain-pass deep brain stimulation. OBJECTIVE: To analyze the intercenter reproducibility of this method for deep brain stimulation. METHODS: A total of 310 leads from 166 patients undergoing surgery were analyzed, including 220 multitrack (primarily 3-track) subthalamic nucleus leads, 17 single-brain-pass subthalamic nucleus leads, and 73 single-brain-pass globus pallidus interna leads. We adopted the previously reported calibration factors. Calibration shifts the frame coordinates from the target coordinates to the left, anterior, and inferior directions by 0, 0.5, or 1 mm, respectively, according to the arc angles in each axis. We analyzed 9 subgroups of single-brain-pass, multitracks, operated sides, technical, and instrumental variations. RESULTS: In total, the stereotactic error decreased from 1.5 ± 0.8 mm in the distance to the frame coordinates (error calculation before using the calibration technique) to 1.1 ± 0.6 mm in the distance to the intended target coordinates (error after using the calibration technique, 28% reduction, P < .000001). Frame-related errors were 0.1 to 0.3 mm when measured with the stereotactic simulator. The reduction of stereotactic errors by the calibration technique (median 0.4 mm, 0.1-0.7 mm, median 28%, 7%-45% in each subgroup) was significant in 8 of the 9 subgroups (P < .05). CONCLUSION: Calibration is an effective and reproducible method for reducing systematic stereotactic errors both in single-brain-pass and multitrack deep brain stimulations, as well as in both sides using various instrumental and technical conditions.

Comparison of the Stereotactic Accuracies of Function-Guided Deep Brain Stimulation, Calculated Using Multitrack Target Locations Geometrically Inferred from Three-Dimensional Trajectory Rotations, and of Magnetic Resonance Imaging-Guided Deep Brain Stimulation and Outcomes.

OBJECTIVE: In previous studies, multitrack trajectories in deep brain stimulation (DBS) have usually been approximated. Using a geometrically more accurate method, we compared the stereotactic accuracy of DBS with multitrack microelectrode recording and awake stimulation (function group) and MRI-guided DBS (MRI group). METHODS: One hundred and seventy-two leads used in DBS between April 2014 and January 2016 were evaluated for stereotactic errors. Targets were the subthalamic nucleus (STN, 139 leads) or globus pallidus interna (GPi, 33 leads). We geometrically calculated shifted-track targets by considering the three-dimensional stereotactic ring and arc rotations. Stereotactic errors were calculated using Euclidean distances perpendicular to trajectories. Motor outcomes according to the Unified Parkinson's Disease Rating Scale (UPDRS) part III, improvement percentages by stimulations, were analyzed in 24 patients with 1 year follow-ups. RESULTS: Functional evaluation tended to increase stereotactic errors in the STN function group (n = 129; 1.4 ± 0.7 mm) more than in the STN MRI group (n = 10; 1.0 ± 0.6 mm; P = 0.06). Leads with higher stereotactic errors (n = 65; 1.6 ± 0.7 mm; P < 0.001) than the center-track leads (n = 64; 1.2 ± 0.7 mm) were selectively track shifted. Track-shifted leads approached MRI targets in 86% (56/65 leads). Lower stereotactic errors tended to correlate with a better outcome (P = 0.095). Distances to MRI targets >2.5 mm tended to relate to a worse outcome (P = 0.087). Stereotactic errors were lower (n = 33; 0.9 ± 0.5 mm) in the GPi MRI group. CONCLUSIONS: Multitrack DBS using intraoperative functional evaluation resulted in worse stereotactic accuracy than did MRI-guided DBS. However, track shifts in function-guided DBS can approach MRI targets effectively.

Gamma-knife subcaudate tractotomy for treatment-resistant depression and target characteristics: a case report and review.

Stereotactic subcaudate tractotomy has previously been suggested to be an effective treatment for depression. This is the first study to report the use of gamma-knife subcaudate tractotomy for treatment-resistant depression. A 49-year-old woman with major depressive disorder had been treated for 30 years, with nine suicide attempts during that time. The right and left target maximum diameter was 11 mm within 50 % isodose lines. The target was located more posteriorly and inferiorly than the subgenual cingulate target typically used for deep-brain stimulation. The maximum radiation dose was 130 Gy. During the 4 months after surgery, the patient improved gradually from 23 to 4 according to the Hamilton Rating Scale for Depression and antidepressant medication was discontinued. Target-sized focal lesions were identified and no edema was seen postoperatively. No aggravation or neurologic deficit occurred during the 2.5 years of follow-up. Gamma-knife subcaudate tractotomy for depression is a minimally invasive technique. Investigations of the effectiveness and safety profile in a larger group are warranted.

Two-Session Tumor and Retrogasserian Trigeminal Nerve-Targeted Gamma Knife Radiosurgery for Secondary Trigeminal Neuralgia Associated with Benign Tumors.

OBJECTIVE: To investigate gamma knife radiosurgery (GKS) for benign tumor-associated secondary trigeminal neuralgia (TN). METHODS: Between 2006 and 2015, 21 patients with secondary TN due to meningioma were treated using GKS. Their mean age was 56.5 ± 12.2 years. The 50% isodose was 12.5 ± 1.1 Gy for the first GKS for the meningioma. Retrogasserian targeting of the trigeminal nerve at 90 Gy with a 4-mm collimator was used for the second GKS. RESULTS: The pain duration until GKS was 1.9 ± 1.9 years. The meningiomas were located in the cisternal space in 13 patients (56.5%) and involved the skull base in 8 patients (43.5%). The mean duration of follow-up was 3.7 ± 2.7 years. The pain control outcome was a Marseilles Pain Scale (MPS) score of I to IV in 15 patients (71%) and a score of V in 6 patients (29%). For these latter patients, we performed a second GKS targeting the trigeminal nerve and resulting in MPS scores of I to IV. The tumor size did not increase in any patient and decreased by >10% in 12 (80%) of the 15 patients who were followed for at least 1 year. Trigeminal nerve visibility may improve after tumor shrinkage. Retrogasserian trigeminal nerve targets may be used even with invisible trigeminal nerves using Meckel's cave as an anatomic marker. CONCLUSIONS: Here we show the reproducible feasibility of a 2-session GKS procedure using higher radiation doses, the first dose to treat the tumor and the second to treat the trigeminal nerves using retrogasserian targeting.

Repeat Gamma-Knife Radiosurgery for Refractory or Recurrent Trigeminal Neuralgia with Consideration About the Optimal Second Dose.

OBJECTIVE: To investigate adequate radiation doses for repeat Gamma Knife radiosurgery (GKS) for trigeminal neuralgia in our series and meta-analysis. METHODS: Fourteen patients treated by ipsilateral repeat GKS for trigeminal neuralgia were included. Median age of patients was 65 years (range, 28-78), the median target dose, 140-180). Patients were followed a median of 10.8 months (range, 1-151) after the second gamma-knife surgery. Brainstem dose analysis and vote-counting meta-analysis of 19 studies were performed. RESULTS: After the second gamma-knife radiosurgeries, pain was relieved effectively in 12 patients (86%; Barrow Neurological Institute Pain Intensity Score I-III). Post-gamma-knife radiosurgery trigeminal nerve deficits were mild in 5 patients. No serious anesthesia dolorosa was occurred. The second GKS radiation dose ≤ 60 Gy was significantly associated with worse pain control outcome (P = 0.018 in our series, permutation analysis of variance, and P = 0.009 in the meta-analysis, 2-tailed Fisher's exact test). Cumulative dose ≤ 140-150 Gy was significantly associated with poor pain control outcome (P = 0.033 in our series and P = 0.013 in the meta-analysis, 2-tailed Fisher's exact test). A cumulative brainstem edge dose >12 Gy tended to be associated with trigeminal nerve deficit (P = 0.077). CONCLUSION: Our study suggests that the second GKS dose is a potentially important factor.

Three-dimensional fluid-attenuated inversion recovery sequence for visualisation of subthalamic nucleus for deep brain stimulation in Parkinson's disease.

INTRODUCTION: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an accepted treatment for advanced Parkinson's disease (PD). However, targeting the STN is difficult due to its relatively small size and variable location. The purpose of this study was to assess which of the following sequences obtained with the 3.0 T MR system can accurately delineate the STN: coronal 3D fluid-attenuated inversion recovery (FLAIR), 2D T2*-weighted fast-field echo (T2*-FFE) and 2D T2-weighted turbo spin-echo (TSE) sequences. METHODS: We included 20 consecutive patients with PD who underwent 3.0 T MR for DBS targeting. 3D FLAIR, 2D T2*-FFE and T2-TSE images were obtained for all study patients. Image quality and demarcation of the STN were analysed using 4-point scales, and contrast ratio (CR) of the STN and normal white matter was calculated. The Friedman test was used to compare the three sequences. RESULTS: In qualitative analysis, the 2D T2*-FFE image showed more artefacts than 3D FLAIR or 2D T2-TSE, but the difference did not reach statistical significance. 3D FLAIR images showed significantly superior demarcation of the STN compared with 2D T2*-FFE and T2-TSE images (P < 0.001, respectively). The CR of 3D FLAIR was significantly higher than that of 2D T2*-FFE or T2-TSE images in multiple comparison correction (P < 0.001), but there was no significant difference in the CR between 2D T2*-FFE and T2-TSE images. CONCLUSION: Coronal 3D FLAIR images showed the most accurate demarcation of the STN for DBS targeting among coronal 3D FLAIR, 2D T2*-FFE and T2-TSE images.

Gamma Knife radiosurgery for recurrent or residual seizures after anterior temporal lobectomy in mesial temporal lobe epilepsy patients with hippocampal sclerosis: long-term follow-up results of more than 4 years.

OBJECT: Gamma Knife radiosurgery (GKRS) has proven efficacy in the treatment of drug-resistant mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) and is comparable to conventional resective surgery. It may be effective as an alternative treatment to reoperation after failed temporal lobe surgery in patients with MTLE-HS. The purpose of this study was to investigate the efficacy of GKRS in patients with unilateral MTLE-HS who did not achieve seizure control or had recurrent seizures after anterior temporal lobectomy (ATL). METHODS: Twelve patients (8 males; mean age 35.50 ± 9.90 years) with MTLE-HS who underwent GKRS after failed ATL (Engel Classes III-IV) were included. GKRS targets included the remnant tissue or adjacent regions of the previously performed ATL with a marginal dose of 24-25 Gy at the 50% isodose line in all patients. Final seizure outcome was assessed using Engel's modified criteria during the final 2 years preceding data analysis. A comparison between signal changes on follow-up MRI and clinical outcome was performed. RESULTS: All patients were followed up for at least 4 years with a mean duration of 6.18 ± 1.77 years (range 4-8.8 years) after GKRS. At the final assessment, 6 of 12 patients were classified as seizure free (Engel Class Ia, n = 3; Ic, n = 2; and Id, n = 1) and 6 patients were classified as not seizure free (Engel Class II, n = 1; III, n = 2; and IV, n = 3). Neither initial nor late MRI signal changes after GKRS statistically correlated with surgical outcome. Clinical seizure outcome did not differ significantly with initial or late MRI changes after GKRS. CONCLUSIONS: GKRS can be considered an alternative option when the patients with MTLE-HS who had recurrent or residual seizures after ATL refuse a second operation.

Long-term outcomes of hemispheric disconnection in pediatric patients with intractable epilepsy.

BACKGROUND AND PURPOSE: Hemispherectomy reportedly produces remarkable results in terms of seizure outcome and quality of life for medically intractable hemispheric epilepsy in children. We reviewed the neuroradiologic findings, pathologic findings, epilepsy characteristics, and clinical long-term outcomes in pediatric patients following a hemispheric disconnection. METHODS: We retrospectively studied 12 children (8 males) who underwent a hemispherectomy at Asan Medical Center between 1997 and 2005. Clinical, EEG, neuroradiological, and surgical data were collected. Long-term outcomes for seizure, motor functions, and cognitive functions were evaluated at a mean follow-up of 12.7 years (range, 7.6-16.2 years) after surgery. RESULTS: The mean age at epilepsy onset was 3.0 years (range, 0-7.6 years). The following epilepsy syndromes were identified in our cohort: focal symptomatic epilepsy (n=8), West syndrome (n=3), and Rasmussen's syndrome (n=1). Postoperative histopathology of our study patients revealed malformation of cortical development (n=7), encephalomalacia as a sequela of infarction or trauma (n=3), Sturge-Weber syndrome (n=1), and Rasmussen's encephalitis (n=1). The mean age at surgery was 6.5 years (range, 0.8-12.3 years). Anatomical or functional hemispherectomy was performed in 8 patients, and hemispherotomy was performed in 4 patients. Eight of our 12 children (66.7%) were seizure-free, but 3 patients with perioperative complications showed persistent seizure. Although all patients had preoperative hemiparesis and developmental delay, none had additional motor or cognitive deficits after surgery, and most achieved independent walking and improvement in daily activities. CONCLUSIONS: The long-term clinical outcomes of hemispherectomy in children with intractable hemispheric epilepsy are good when careful patient selection and skilled surgical approaches are applied.

Long-term outcome of gamma knife surgery using a retrogasserian petrous bone target for classic trigeminal neuralgia.

BACKGROUND: Gamma knife surgery (GKS) is the prevailing method for treatment of medically intractable trigeminal neuralgia (TN), although there are some technical differences among radiosurgical centers. We assessed the long-term outcomes of GKS using retrogasserian petrous bone targeting and evaluated factors associated with the clinical outcomes. METHODS: Between December 2003 and June 2009, a total of 91 GKS treatments were performed in 90 patients with classic TN. The surgical target was defined at the anterior portion of the trigeminal nerve, just above the retrogasserian petrous bone. A single 4-mm collimator was used to deliver a median 88.0 Gy (range 75-90 Gy) dose of radiation. FINDINGS: During follow-up, which ranged from 24 to 90 months, 89 patients (97.8 %) reported initial pain relief, 75 (82.4 %) experienced pain control, and 47 (51.6 %) achieved a pain-free state without medications at the last follow-up. Barrow Neurological Institute (BNI) scores of I-III at 2, 3, 4, 5, and 7 years were observed in 84 of 91, 68 of 77, 46 of 53, 33 of 36, 17 of 19, and 7 of 7 patients, respectively. Trigeminal nerve dysfunction was experienced by 34 patients, with 12 having BNI facial numbness scores of III-IV (13.2 %). In all, 14 patients (15.4 %) experienced pain recurrence at a mean 32 months (range 10-62 months) after treatment. The actuarial rates of pain control at 2, 4, and 6 years were 93 %, 88 %, and 79 %, respectively. CONCLUSIONS: Gamma Knife radiosurgery is an efficient option for intractable TN. Our results can help medical practitioners to counsel their patients on the likelihood of achieving successful pain control.

Surgical treatment for localization-related infantile spasms: excellent long-term outcomes.

OBJECTIVE: Focal epileptogenic lesions can manifest as infantile spasms, a catastrophic type of epilepsy. Although early surgery for catastrophic epilepsies has shown positive effects, little is known regarding long-term outcomes. The present study examined long-term outcomes in patients with localization-related infantile spasms treated surgically. METHODS: Data from localization-related infantile spasm cases treated surgically between 1998 and 2002 at the Asan Medical Center were retrospectively reviewed. Presurgical evaluation, surgery, postoperative seizure frequency and developmental outcome data were analyzed. RESULTS: Five patients met the inclusion criteria, and had etiologies of tuberous sclerosis, fetal infection, encephalomalacia, malformation of cortical development and low-grade astrocytoma, respectively. The mean seizure onset age was 5.4 months (range, 3 days to 11 months), and the mean age at surgery was 19 months (range, 9-29 months). Two patients underwent a functional hemispherectomy, and the remaining three underwent lesionectomy or temporal lobectomy. The follow-up duration was 6-9 years. We found that following surgery, 4 of the 5 patients were seizure-free at the final follow-up. The 2 patients with low grade astrocytoma and cortical dysplasia, respectively showed relatively good developmental outcomes. CONCLUSION: Surgery may be an excellent option for treating selected patients with infantile spasms due to unilateral or focal congenital or early-acquired cortical lesions. However, developmental outcomes appear to be strongly linked to etiology and the pre-operative developmental level.

MR spectroscopy and perfusion MR imaging findings of intracranial foreign body granuloma: a case report.

We report a case of intracranial foreign body granuloma that showed features of a high grade tumor on magnetic resonance (MR) imaging. However, the relative cerebral blood volume was not increased in the enhancing mass on perfusion MRI and the choline/creatine ratio only slightly increased on MR spectroscopy. The results suggest that the lesion is benign in nature. Perfusion MRI and MR spectroscopy may be helpful to differentiate a foreign body granuloma from a neoplastic condition.

Malignant transformation of monostotic fibrous dysplasia in the mandible.

Malignant transformation of fibrous dysplasia (FD), which was first introduced by Coley and Steward is very rare. We present a case of malignant transformation of monostotic mandibular FD after 2 surgical excisions, 20 and 15 years ago, respectively. The treatment choice of FD is usually conservative. With the advanced surgical techniques, radical excisions followed by immediate reconstruction have been reported. However, the decision criteria are still controversial and we might think that radical treatment is a good method for recurrent lesions based on the recent literatures. The case discussed here is of sarcomatous transformation of a recurrent FD.

High-level cervical spinal cord stimulation used to treat intractable pain arising from transverse myelitis caused by schistosomiasis.

The efficacy of spinal cord stimulation (SCS) for treatment of various chronic painful conditions is well established. Very few reports have documented the use of SCS for treatment of chronic pain after spinal cord injury. We present a case showing a good outcome after such treatment, and suggest that high cervical stimulation may be efficacious. A 53-year-old male underwent SCS on the C1-3 level for treatment of intractable neuropathic pain below the T3 level, and in the upper extremities, arising from spinal cord injury resulting from transverse myelitis caused by schistosomiasis. High cervical SCS significantly improved the pain in the upper extremities and at the T3-T10 dermatome level. The patient continues to report excellent pain relief 9 months later. The present case suggests that high cervical stimulation may improve chronic pain in the upper extremities and the T3-T10 dermatome level arising from spinal cord injury.

Salvage techniques for STA-MCA bypass.

Superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass is a well-established, indispensable neurosurgical procedure. It is technically challenging, and surgeons must be prepared for unexpected problems. The present report describes four cases where problems arose that resulted in graft occlusion. None of these problems was directly related to the anastomosis procedure, and they occurred from early in the operation (e.g., STA preparation) to late (e.g., skin closure). In all cases, the salvage procedures used were successful, and postoperative angiography demonstrated good bypass patency.

Vagus nerve stimulation for intractable epilepsy: outcomes in children and adults.

Objectives. Vagus nerve stimulation (VNS) is an accepted treatment for medically intractable epilepsy. However, predictive factors associated with responsiveness to VNS remained unclear. We therefore sought to identify predictive factors that influence responsiveness to VNS in both children and adults. Materials and Methods. We evaluated a retrospective series of 31 patients who underwent VNS for intractable epilepsy at Asan Medical Center from 1998 to 2006. Eighteen patients were younger than 18 years, while 13 patients were aged 18 years or older. We assessed mean seizure frequency, the number of antiepileptic drugs each patient was taking, seizure type, etiology, age at seizure onset, age at implantation, and duration of epilepsy. Results. Forty-three percent of all patients had a seizure reduction of more than 50%. Ten (59%) children had a 50% reduction in their seizures, while three adults (23%) had such a response. Two factors were significantly different between responders and non-responders: age at implantation and age of seizure onset. In a logistic regression analysis, however, no factors were independently associated with the response to VNS. Transient hoarseness and cough were observed in eight of all patients and wound infection and generator failure in one patient each. Conclusions. These results suggest that VNS may be a more effective treatment in children with intractable epilepsy than in adults. It remains difficult to predict which patients will respond to VNS therapy.