Abstract
Commonly used for Parkinson’s disease (PD), deep brain stimulation (DBS) produces marked clinical benefits when optimized. However, assessing the large number of possible stimulation ...settings (i.e., programming) requires numerous clinic visits. Here, we examine whether functional magnetic resonance imaging (fMRI) can be used to predict optimal stimulation settings for individual patients. We analyze 3 T fMRI data prospectively acquired as part of an observational trial in 67 PD patients using optimal and non-optimal stimulation settings. Clinically optimal stimulation produces a characteristic fMRI brain response pattern marked by preferential engagement of the motor circuit. Then, we build a machine learning model predicting optimal vs. non-optimal settings using the fMRI patterns of 39 PD patients with a priori clinically optimized DBS (88% accuracy). The model predicts optimal stimulation settings in unseen datasets: a priori clinically optimized and stimulation-naïve PD patients. We propose that fMRI brain responses to DBS stimulation in PD patients could represent an objective biomarker of clinical response. Upon further validation with additional studies, these findings may open the door to functional imaging-assisted DBS programming.
Outcomes from stereotactic surgery for essential tremor Dallapiazza, Robert Francis; Lee, Darrin J; De Vloo, Philippe ...
Journal of neurology, neurosurgery and psychiatry,
04/2019, Letnik:
90, Številka:
4
Journal Article
Recenzirano
Odprti dostop
There are several different surgical procedures that are used to treat essential tremor (ET), including deep brain stimulation (DBS) and thalamotomy procedures with radiofrequency (RF), radiosurgery ...(RS) and most recently, focused ultrasound (FUS). Choosing a surgical treatment requires a careful presentation and discussion of the benefits and drawbacks of each. We conducted a literature review to compare the attributes and make an appraisal of these various procedures. DBS was the most commonly reported treatment for ET. One-year tremor reductions ranged from 53% to 63% with unilateral Vim DBS. Similar improvements were demonstrated with RF (range, 74%-90%), RS (range, 48%-63%) and FUS thalamotomy (range, 35%-75%). Overall, bilateral Vim DBS demonstrated more improvement in tremor reduction since both upper extremities were treated (range, 66%-78%). Several studies show continued beneficial effects from DBS up to five years. Long-term follow-up data also support RF and gamma knife radiosurgical thalamotomy treatments. Quality of life measures were similarly improved among patients who received all treatments. Paraesthesias, dysarthria and ataxia were commonly reported adverse effects in all treatment modalities and were more common with bilateral DBS surgery. Many of the neurological complications were transient and resolved after surgery. DBS surgery had the added benefit of programming adjustments to minimise stimulation-related complications. Permanent neurological complications were most commonly reported for RF thalamotomy. Thalamic DBS is an effective, safe treatment with a long history. For patients who are medically unfit or reluctant to undergo DBS, several thalamic lesioning methods have parallel benefits to unilateral DBS surgery. Each of these surgical modalities has its own nuance for treatment and patient selection. These factors should be carefully considered by both neurosurgeons and patients when selecting an appropriate treatment for ET.
Trigeminal neuralgia patients have microstructural abnormalities in their trigeminal nerves and brain white matter connecting regions involved in pain perception, attention, and motor functions.
...Idiopathic trigeminal neuralgia (TN) is classically associated with neurovascular compression (NVC) of the trigeminal nerve at the root entry zone (REZ), but NVC-induced structural alterations are not always apparent on conventional imaging. Previous studies report lower fractional anisotropy (FA) in the affected trigeminal nerves of TN patients using diffusion tensor imaging (DTI). However, it is not known if TN patients have trigeminal nerve abnormalities of mean, radial, or axial diffusivity (MD, RD, AD – metrics linked to neuroinflammation and edema) or brain white matter (WM) abnormalities. DTI scans in 18 right-sided TN patients and 18 healthy controls were retrospectively analyzed to extract FA, RD, AD, and MD from the trigeminal nerve REZ, and Tract-Based Spatial Statistics (TBSS) was used to assess brain WM. In patients, the affected trigeminal nerve had lower FA, and higher RD, AD, and MD was found bilaterally compared to controls. Group TBSS (P<0.05, corrected) showed patients had lower FA and increased RD, MD, and AD in brain WM connecting areas involved in the sensory and cognitive-affective dimensions of pain, attention, and motor functions, including the corpus callosum, cingulum, posterior corona radiata, and superior longitudinal fasciculus. These data indicate that TN patients have abnormal tissue microstructure in their affected trigeminal nerves, and as a possible consequence, WM microstructural alterations in the brain. These findings suggest that trigeminal nerve structural abnormalities occur in TN, even if not apparent on gross imaging. Furthermore, MD and RD findings suggest that neuroinflammation and edema may contribute to TN pathophysiology.
Ventral intermediate thalamic stimulation is effective in treating essential tremor and tremor-dominant Parkinson's disease, but its precise mechanism of action is unclear. Milosevic et al. show that ...thalamic inhibition of neuronal firing is necessary for tremor reduction, suggesting that the thalamus acts as a filter for uncoupling central and peripheral tremor networks.
Abstract
Ventral intermediate thalamic deep brain stimulation is a standard therapy for the treatment of medically refractory essential tremor and tremor-dominant Parkinson's disease. Despite the therapeutic benefits, the mechanisms of action are varied and complex, and the pathophysiology and genesis of tremor remain unsubstantiated. This intraoperative study investigated the effects of high frequency microstimulation on both neuronal firing and tremor suppression simultaneously. In each of nine essential tremor and two Parkinson's disease patients who underwent stereotactic neurosurgery, two closely spaced (600 µm) microelectrodes were advanced into the ventral intermediate nucleus. One microelectrode recorded action potential firing while the adjacent electrode delivered stimulation trains at 100 Hz and 200 Hz (2-5 s, 100 µA, 150 µs). A triaxial accelerometer was used to measure postural tremor of the contralateral hand. At 200 Hz, stimulation led to 68 ± 8% (P < 0.001) inhibition of neuronal firing and a 53 ± 5% (P < 0.001) reduction in tremor, while 100 Hz reduced firing by 26 ± 12% (not significant) with a 17 ± 6% (P < 0.05) tremor reduction. The degree of cell inhibition and tremor suppression were significantly correlated (P < 0.001). We also found that the most ventroposterior stimulation sites, closest to the border of the ventral caudal nucleus, had the best effect on tremor. Finally, prior to the inhibition of neuronal firing, microstimulation caused a transient driving of neuronal activity at stimulus onset (61% of sites), which gave rise to a tremor phase reset (73% of these sites). This was likely due to activation of the excitatory glutamatergic cortical and cerebellar afferents to the ventral intermediate nucleus. Temporal characteristics of the driving responses (duration, number of spikes, and onset latency) significantly differed between 100 Hz and 200 Hz stimulation trains. The subsequent inhibition of neuronal activity was likely due to synaptic fatigue. Thalamic neuronal inhibition seems necessary for tremor reduction and may function in effect as a thalamic filter to uncouple thalamo-cortical from cortico-spinal reflex loops. Additionally, our findings shed light on the gating properties of the ventral intermediate nucleus within the cerebello-thalamo-cortical tremor network, provide insight for the optimization of deep brain stimulation technologies, and may inform controlled clinical studies for assessing optimal target locations for the treatment of tremor.
Deep Brain Stimulation (DBS) is an effective treatment extended broadly to many neurological and psychiatric disorders. Nevertheless, complications may arise during DBS procedures or following ...implantation due to implanted hardware. This may result in both minor and major adverse events that may necessitate hardware removal and/or compromise maximal therapeutic benefit for the patient.
To identify relevant literature on hardware-related complications from DBS procedures by performing a systematic review, and propose how to identify at-risk group and possible preventive approaches.
Of 4592 abstract screened, 96 articles fulfilled the selection criteria and were reviewed. Overall, the most common hardware-related complications were infections (5.12% of patients), followed by lead migration (1.60%), fracture or failure of the lead or other parts of the implant (1.46% and 0.73%, respectively), IPG malfunctions (1.06% of patients), and skin erosions without infections (0.48% of patients). New indications for DBS, including Tourette's syndrome, cluster headache, and refractory partial epilepsy, were found to bear a higher incidence of hardware-related infections than established indications such as Parkinson's disease. The highest rate of lead fracture or failure was found in dystonia patients (4.22%). Ultimately, the highest rate of pain at the implantation sites was found in refractory partial epilepsy patients (16.55%).
Our analysis identified a variety of potential hardware-related complications among patients who underwent DBS procedures. Patients who were at risk of complications, such as patients with dystonia and off-label indications (e.g. Tourette's syndrome) should be informed prior to surgery and closely followed thereafter.
•This review identified the potential hardware-related complications from DBS procedures.•New indications for DBS were found a higher incidence of infections than established indications.•Patients who are at risk of complications should be informed prior and closely followed thereafter.
Chronic pain has widespread, detrimental effects on the human nervous system and its prevalence and burden increase with age. Machine learning techniques have been applied on brain images to produce ...statistical models of brain aging. Specifically, the Gaussian process regression is particularly effective at predicting chronological age from neuroimaging data which permits the calculation of a brain age gap estimate (brain-AGE). Pathological biological processes such as chronic pain can influence brain-AGE. Because chronic pain disorders can differ in etiology, severity, pain frequency, and sex-linked prevalence, we hypothesize that the expression of brain-AGE may be pain specific and differ between discrete chronic pain disorders. We built a machine learning model using T1-weighted anatomical MRI from 812 healthy controls to extract brain-AGE for 45 trigeminal neuralgia (TN), 52 osteoarthritis (OA), and 50 chronic low back pain (BP) subjects. False discovery rate corrected Welch t tests were conducted to detect significant differences in brain-AGE between each discrete pain cohort and age-matched and sex-matched controls. Trigeminal neuralgia and OA, but not BP subjects, have significantly larger brain-AGE. Across all 3 pain groups, we observed female-driven elevation in brain-AGE. Furthermore, in TN, a significantly larger brain-AGE is associated with response to Gamma Knife radiosurgery for TN pain and is inversely correlated with the age at diagnosis. As brain-AGE expression differs across distinct pain disorders with a pronounced sex effect for female subjects. Younger women with TN may therefore represent a vulnerable subpopulation requiring expedited chronic pain intervention. To this end, brain-AGE holds promise as an effective biomarker of pain treatment response.
Abstract Background Neurosurgery in low-income countries is faced with multiple challenges. While the most common challenges include infrastructure and physical resource deficits, an underemphasized ...barrier relates to the methods and components of surgical training. The role of important aspects including didactic surgical training, surgical decision-making, workshops, conferences, and assessment methods have not been duly studied. Knowledge of these issues is a crucial step to move closer to strengthening surgical capacity in low income countries. Methods We designed an online survey to assess self-perceived as well as objectively-measured barriers to neurosurgical training in various sub-Saharan African countries. Key outcomes included perception toward adequacy of neurosurgery training, as well as barriers to neurosurgical training at each individual site. Results Only 37% of responders felt that their training program adequately prepared them for handling the incoming neurosurgical cases. Top perceived limitations of neurosurgery training included lack of physical resources (25% of all responses), lack of practical workshops (22%), lack of program structure (18%), and lack of topic-specific lectures (10%). Conclusions Our results show that the majority of responders believe their training program is inadequate and are interested in improving it through international collaborations. This implies that activities directed at strengthening surgical capacity must address this important necessity. One important strategy is the use of online educational tools. In consideration of the observed limitations in care, resources, and training, we recommend a phased approach to neurosurgical growth in low income settings.
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