Does Head Positioning After Percutaneous Glycerol Rhizotomy for Trigeminal Neuralgia Matter?

BACKGROUND

Percutaneous glycerol rhizotomy (PGR) is a minimally invasive procedure for patients with trigeminal neuralgia who are not candidates for microvascular decompression. PGR has widely varying success rates. It has been postulated that differences in post-injection head positioning might account for the various success rates.

METHODS

By comparing glycerol dispersion after injection at various head positions, we provide the first evidence supporting post-injection head flexion positioning. Furthermore, we study the clival-Meckel cave (CMC) angle as a predictor of beneficial glycerol flow, measured on computed tomography images. Twenty-two dissected cadaveric specimens were injected with dyed glycerol through the Hartel approach. The glycerol dispersion was measured at prespecified intervals for 1 hour. The Mann-Whitney U and χ2 tests were used to determine the most ideal angle of head flexion to avoid posterior glycerol dispersion and ensure V1-V3 branch glycerol submersion.

RESULTS

We found that 30° of anterior head flexion provided optimal trigeminal nerve glycerol submersion (81.82%) in comparison to neutral (27.27%) and 15° (68.18%), P < 0.001. There was minimal unfavorable dispersion beyond 30 minutes at all angles. More obtuse CMC angles were associated with higher rates of unfavorable BC dispersion (U = 6.0; P = 0.001). For specimens with CMC angles >75°, unfavorable BC dispersion was prevented by head flexion (U = 4.5; P = 0.021). We show that 30° of lateral head tilt achieves V1 submersion in all specimens by 30 minutes [X2(1,N = 44) = 22.759; P < 0.001].

CONCLUSIONS

We found that 30° anterior head flexion for >30 minutes provides ideal conditions for PGR to avoid BC dispersion and ensure V1-V3 branches achieve glycerol submersion. For patients with V1 symptoms, contralateral head flexion might help optimize treatment effects.

Deep brain stimulation for substance use disorder: a systematic review and meta-analysis

Objective

Substance use disorder (SUD) is a significant public health issue with a high mortality rate. Deep brain stimulation (DBS) has shown promising results in treating SUD in certain cases. In this study, we conducted a meta-analysis to evaluate the efficacy of DBS in the treatment of SUD and reduction of relapse rates.

Methods

We performed a thorough and methodical search of the existing scientific literature, adhering to the PRISMA guidelines, to identify 16 original studies that fulfilled our inclusion criteria. We used the evidence levels recommended by the Oxford Centre for Evidence-Based Medicine to assess bias. The R version 4.2.3 software was utilized to calculate the mean effect size. We estimated study heterogeneity by employing tau2 and I2 indices and conducting Cochran's Q test.

Results

The results showed that DBS treatment resulted in a significant improvement in the clinical SUD scales of patients, with an average improvement of 59.6%. The observed relapse rate was 8%. The meta-analysis estimated a mean effect size of 55.9 [40.4; 71.4]. Heterogeneity analysis showed a large degree of heterogeneity among the included studies. Subgroup and meta-regression analysis based on age and SUD type suggested that DBS may be more effective for patients above 45 years of age, and for alcohol and opioid addiction compared to nicotine addiction.

Conclusion

The current literature suggests that DBS has a moderate effect on SUD symptoms. However, the limited number of studies and small sample size indicate that more research is needed to better understand the factors that influence its effectiveness.

Effects of Very Low- and High-Frequency Subthalamic Stimulation on Motor Cortical Oscillations During Rhythmic Lower-Limb Movements in Parkinson's Disease Patients

BACKGROUND

Standard high-frequency deep brain stimulation (HF-DBS) at the subthalamic nucleus (STN) is less effective for lower-limb motor dysfunctions in Parkinson's disease (PD) patients. However, the effects of very low frequency (VLF; 4 Hz)-DBS on lower-limb movement and motor cortical oscillations have not been compared.

OBJECTIVE

To compare the effects of VLF-DBS and HF-DBS at the STN on a lower-limb pedaling motor task and motor cortical oscillations in patients with PD and with and without freezing of gait (FOG).

METHODS

Thirteen PD patients with bilateral STN-DBS performed a cue-triggered lower-limb pedaling motor task with electroencephalography (EEG) in OFF-DBS, VLF-DBS (4 Hz), and HF-DBS (120-175 Hz) states. We performed spectral analysis on the preparatory signals and compared GO-cue-triggered theta and movement-related beta oscillations over motor cortical regions across DBS conditions in PD patients and subgroups (PDFOG-and PDFOG+).

RESULTS

Both VLF-DBS and HF-DBS decreased the linear speed of the pedaling task in PD, and HF-DBS decreased speed in both PDFOG-and PDFOG+. Preparatory theta and beta activities were increased with both stimulation frequencies. Both DBS frequencies increased motor cortical theta activity during pedaling movement in PD patients, but this increase was only observed in PDFOG + group. Beta activity was not significantly different from OFF-DBS at either frequency regardless of FOG status.

CONCLUSION

Results suggest that VL and HF DBS may induce similar effects on lower-limb kinematics by impairing movement speed and modulating motor cortical oscillations in the lower frequency band.

A retrospective comparison of cognitive performance in individuals with advanced Parkinson's Disease in Hong Kong and Canada

A deeper understanding of the cross-cultural applicability of cognitive tests across countries and cultures is needed to better equip neuropsychologists for the assessment of patients from diverse backgrounds. Our study compared cognitive test scores in patients with advanced Parkinson's disease (PD) at the Prince of Wales Hospital (n = 63; Hong Kong) and the Foothills Medical Center (n = 20; Calgary, Canada). The groups did not differ in age or sex (p > .05), but Western patients had significantly more years of education (M = 14.2, SD = 2.7) than Asian patients (M = 10.33, SD = 4.4). Cognitive tests administered to both groups included: digit span, verbal fluency (animals), the Boston Naming Test, and verbal memory (California Verbal Learning Test or Chinese Auditory Verbal Learning Test). Testing was completed before and 12 months after deep brain stimulation surgery. Results showed cognitive performance was similar across time, but significant group differences were found on digit span forward (longer among patients from Hong Kong; F(1, 75) = 44.155, p < .001) and the Boston Naming Test (higher percent spontaneous correct among patients from Canada; F(1, 62) = 7.218, p = .009, η² = 0.104), after controlling for age, sex, and years of education. In conclusion, our findings provide preliminary support for the similarity of Chinese versions of tests originally developed for Western populations. Also, we caution that some aspects of testing may be susceptible to cultural bias and therefore warrant attention in clinical practice and refinement in future test development for Asian patients.

Computer-assisted planning for minimally invasive anterior two-thirds laser corpus callosotomy: A feasibility study with probabilistic tractography validation

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Laser interstitial thermal therapy (LITT) is a novel minimally invasive technique for the treatment of epilepsy.

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We test computer assisted planning with LITT to disrupt seizure spread.

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Trajectory parameters and models were automatically generated from a single T1 image.

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Probabilistic tractography revealed comparable interhemispheric disconnection to blinded expert surgeons.

Background

Anterior two-thirds corpus callosotomy is an effective palliative neurosurgical procedure for drug-refractory epilepsy that is most commonly used to treat drop-attacks. Laser interstitial thermal therapy is a novel stereotactic ablative technique that has been utilised as a minimally invasive alternative to resective and disconnective open neurosurgery. Case series have reported success in performing laser anterior two-thirds corpus callosotomy. Computer-assisted planning algorithms may help to automate and optimise multi-trajectory planning for this procedure.

Objective

To undertake a simulation-based feasibility study of computer-assisted corpus callostomy planning in comparison with expert manual plans in the same patients.

Methods

Ten patients were selected from a prospectively maintained database. Patients had previously undergone diffusion-weighted imaging and digital subtraction angiography as part of routine SEEG care. Computer-assisted planning was performed using the EpiNav™ platform and compared to manually planned trajectories from two independent blinded experts. Estimated ablation cavities were used in conjunction with probabilistic tractography to simulate the expected extent of interhemispheric disconnection.

Results

Computer-assisted planning resulted in significantly improved trajectory safety metrics (risk score and minimum distance to vasculature) compared to blinded external expert manual plans. Probabilistic tractography revealed residual interhemispheric connectivity in 1/10 cases following computer-assisted planning compared to 4/10 and 2/10 cases with manual planning.

Conclusion

Computer-assisted planning successfully generates multi-trajectory plans capable of LITT anterior two-thirds corpus callosotomy. Computer-assisted planning may provide a means of standardising trajectory planning and serves as a potential new tool for optimising trajectories. A prospective validation study is now required to determine if this translates into improved patient outcomes.

Management of Early Parkinson Disease

Early Parkinson disease is the approximate time period between initial diagnosis and the onset of motor fluctuations. Treatment requires an integrative approach, including identification of motor and nonmotor symptoms, choice of pharmacologic treatment, and emphasis on exercise. Patients should be treated for motor symptoms, whereas medications may be delayed for milder symptoms. The choice of treatment in patients with early Parkinson disease must be weighed against financial considerations, ease of administration, and potential long-term adverse events. Nonmotor symptoms should also be identified and treated. Exercise is an important component for treatment of Parkinson disease at any stage.

The neurobiology of bipolar disorder: focus on signal transduction pathways and the regulation of gene expression

OBJECTIVE

This article presents an overview of signal transduction pathways and reviews the research undertaken to study these systems in clinically relevant samples from patients with bipolar disorder (BD).

METHOD

We reviewed the published findings from studies of postmortem brain tissue and blood samples from patients with BD.

RESULTS

Although the exact biochemical abnormalities have yet to be identified, the presented findings strongly suggest that BD may be due, at least in part, to abnormalities in signal transduction mechanisms. In particular, altered levels or function, or both, of G-protein alpha subunits and effector molecules such as protein kinase A (PKA) and protein kinase C (PKC) have consistently been associated with BD both in peripheral cells and in postmortem brain tissue, while more recent studies implicate disruption in novel second-messenger cascades, such as the ERK/MAPK pathway.

CONCLUSIONS

Despite the difficulties inherent in biochemical studies of clinically relevant tissue samples, numerous investigations have illuminated the signal transduction mechanisms in patients with BD. These studies also suggest that BD may be due to the interaction of many abnormalities. In this context, novel techniques enabling the study of gene expression promise to assist in untangling these complex interactions, through visualizing the end result of these changes at the level of gene transcription.