Zona incerta stimulation

Zona incerta stimulation

Surgical targets for Tourette’s syndrome have included the frontal lobes, the cingulate gyrus, the anterior limb of the internal capsule (ALIC), the limbic system, and the subthalamic zona incerta1) Current targets of interest for DBS include: GPiSTN, ALIC, and thalamus. Early results have been promising. 2).

Posterior subthalamic deep brain stimulation (DBS) targeting the zona incerta (ZI) is an emerging treatment for tremor syndromes, including Parkinson’s disease (PD) and essential tremor (ET).

Evidence from animal studies has indicated that the ZI may play a role in saccadic eye movements via pathways between the ZI and superior colliculus (incerto collicular pathways).


Optics can be used for guidance in deep brain stimulation (DBS) surgery. The aim of Zsigmond and Wårdell was to use laser Doppler flowmetry (LDF) to investigate the intraoperative optical trajectory along the ventral intermediate nucleus (VIM) and zona incerta (Zi) regions in patients with essential tremor during asleep DBS surgery, and whether the Zi region could be identified.

A forward-looking LDF guide was used for the creation of the trajectory for the DBS lead, and the microcirculation and tissue greyness, i.e., total light intensity (TLI) was measured along 13 trajectories. TLI trajectories and the number of high-perfusion spots were investigated at 0.5-mm resolution in the last 25 mm from the targets.

All implantations were done without complications and with significant improvement of tremor (p < 0.01). Out of 798 measurements, 12 tissue spots showed high blood flow. The blood flow was significantly higher in VIM than in Zi (p < 0.001). The normalized mean TLI curve showed a significant (p < 0.001) lower TLI in the VIM region than in the Zi region.

Zi DBS performed asleep appears to be safe and effective. LDF monitoring provides direct in vivo measurement of the microvascular blood flow in front of the probe, which can help reduce the risk of hemorrhage. LDF can differentiate between the grey matter in the thalamus and the transmission border entering the posterior subthalamic area where the tissue consists of more white matter tract3).


Sixteen patients (12 with PD and 4 with ET) underwent DBS using the MRI-directed implantable guide tube technique. Active electrode positions were confirmed at the caudal ZI. Eye movements were tested using direct current electrooculography (EOG) in the medicated state pre- and postoperatively on a horizontal predictive task subtending 30°. Postoperative assessments consisted of stimulation-off, constituting a microlesion (ML) condition, and high-frequency stimulation (HFS; frequency = 130 Hz) up to 3 V.

With PSA HFS, the first saccade amplitude was significantly reduced by 10.4% (95% CI 8.68%-12.2%) and 12.6% (95% CI 10.0%-15.9%) in the PD and ET groups, respectively. With HFS, peak velocity was reduced by 14.7% (95% CI 11.7%-17.6%) in the PD group and 27.7% (95% CI 23.7%-31.7%) in the ET group. HFS led to PD patients performing 21% (95% CI 16%-26%) and ET patients 31% (95% CI 19%-38%) more saccadic steps to reach the target.

PSA DBS in patients with PD and ET leads to hypometric, slowed saccades with an increase in the number of steps taken to reach the target. These effects contrast with the saccadometric findings observed with subthalamic nucleus DBS. Given the location of the active contacts, incerto-collicular pathways are likely responsible. Whether the acute finding of saccadic impairment persists with chronic PSA stimulation is unknown 4).

References

1)

Temel Y, Visser-Vandewalle V. Surgery in Tourette syndrome. Mov Disord. 2004; 19:3–14
2)

Martinez-Fernandez R, Zrinzo L, Aviles-Olmos I, et al. Deep brain stimulation for Gilles de la Tourette syndrome: a case series targeting subre- gions of the globus pallidus internus. Mov Disord. 2011; 26:1922–1930
3)

Zsigmond P, Wårdell K. Optical Measurements during Asleep Deep Brain Stimulation Surgery along Vim-Zi Trajectories. Stereotact Funct Neurosurg. 2020 Feb 20:1-7. doi: 10.1159/000505708. [Epub ahead of print] PubMed PMID: 32079023.
4)

Bangash OK, Dissanayake AS, Knight S, Murray J, Thorburn M, Thani N, Bala A, Stell R, Lind CRP. Modulation of saccades in humans by electrical stimulation of the posterior subthalamic area. J Neurosurg. 2019 Mar 15:1-9. doi: 10.3171/2018.12.JNS18502. [Epub ahead of print] PubMed PMID: 30875687.

Microvascular decompression for trigeminal neuralgia

Microvascular decompression for trigeminal neuralgia

see Microvascular decompression for trigeminal neuralgia and multiple sclerosis

see Awake Microvascular Decompression for Trigeminal Neuralgia

see also Endoscope assisted microvascular decompression for trigeminal neuralgia.

Microvascular decompression is a first-line neurosurgical approach for classical trigeminal neuralgia with neurovascular conflict, but can show clinical relapse despite proper decompression. Second-line destructive techniques like radiofrequency thermocoagulation have become reluctantly used due to their potential for irreversible side effects. Subcutaneous peripheral nerve field stimulation (sPNFS) is a minimally invasive neuromodulatory technique which has been shown to be effective for chronic localised pain conditions.

The most frequently used surgical management of trigeminal neuralgia is Microvascular decompression (MVD), followed closely by stereotactic radiosurgery (SRS). Percutaneous stereotactic rhizotomy (PSR) , despite being the most cost-effective, is by far the least utilized treatment modality 1).

Microvascular decompression (MVD) via lateral suboccipital approach is the standard surgical intervention for trigeminal neuralgia treatment.

Teflon™ and Ivalon® are two materials used in MVD for TN. It is an effective treatment with long-term symptom relief and recurrence rates of 1-5% each year. Ivalon® has been used less than Teflon™ though is associated with similar success rates and similar complication rates 2)

Although microvascular decompression (MVD) is the most effective long-term operative treatment for TN, its use in older patient populations has been debated due to its invasive nature.


Compared with the standard microscope-assisted techniques, the 3D exoscopic endoscope-assisted MVD offers an improved visualisation without compromising the field of view within and outside the surgical field 3).

Systematic Review and Meta-Analysis

Using preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, PubMedCochrane Library, and Scopus were queried for primary studies examining pain outcomes after MVD for TN published between 1988 and March 2018. Potential biases were assessed for included studies. Pain freedom (ie, Barrow Neurological Institute score of 1) at last follow-up was the primary outcome measure. Variables associated with pain freedom on preliminary analysis underwent formal meta-analysis. Odds ratios (OR) and 95% confidence intervals (CI) were calculated for possible predictors.

Outcome data were analyzed for 3897 patients from 46 studies (7 prospective, 39 retrospective). Overall, 76.0% of patients achieved pain freedom after MVD with a mean follow-up of 1.7 ± 1.3 (standard deviation) yr. Predictors of pain freedom on meta-analysis using random effects models included (1) disease duration ≤5 yr (OR = 2.06, 95% CI = 1.08-3.95); (2) arterial compression over venous or other (OR = 3.35, 95% CI = 1.91-5.88); (3) superior cerebellar artery involvement (OR = 2.02, 95% CI = 1.02-4.03), and (4) type 1 Burchiel classification (OR = 2.49, 95% CI = 1.32-4.67).

Approximately three-quarters of patients with drug-resistant TN achieve pain freedom after MVD. Shorter disease duration, arterial compression, and type 1 Burchiel classification may predict a more favorable outcome. These results may improve patient selection and provider expectations 4).

Technique

Outcome

Complications

Case series

References

1)

Sivakanthan S, Van Gompel JJ, Alikhani P, van Loveren H, Chen R, Agazzi S. Surgical management of trigeminal neuralgia: use and cost-effectiveness from an analysis of the medicare claims database. Neurosurgery. 2014 Sep;75(3):220-6. doi: 10.1227/NEU.0000000000000430. PubMed PMID: 24871139.
2)

Pressman E, Jha RT, Zavadskiy G, Kumar JI, van Loveren H, van Gompel JJ, Agazzi S. Teflon™ or Ivalon®: a scoping review of implants used in microvascular decompression for trigeminal neuralgia. Neurosurg Rev. 2019 Nov 30. doi: 10.1007/s10143-019-01187-0. [Epub ahead of print] Review. PubMed PMID: 31786660.
3)

Li Ching Ng A, Di Ieva A. How I do it: 3D exoscopic endoscope-assisted microvascular decompression. Acta Neurochir (Wien). 2019 May 29. doi: 10.1007/s00701-019-03954-w. [Epub ahead of print] PubMed PMID: 31144166.
4)

Holste K, Chan AY, Rolston JD, Englot DJ. Pain Outcomes Following Microvascular Decompression for Drug-Resistant Trigeminal Neuralgia: A Systematic Review and Meta-Analysis. Neurosurgery. 2020 Feb 1;86(2):182-190. doi: 10.1093/neuros/nyz075. PubMed PMID: 30892607.

The Neuromodulation Casebook

The Neuromodulation Casebook

by Jeffrey Arle (Editor)

List Price:$99.95

Buy

The Neuromodulation Casebook is a case-based volume for practical, hands-on decision-making using realistic case examples from the field of neuromodulation. It encompasses a variety of techniques and therapies, ranging from deep brain stimulation for a multitude of disorders to spinal cord stimulation, peripheral nerve stimulation, cortical stimulation, and cranial nerve stimulation, as well as non-invasive therapies and other implanted types of devices that interface with the nervous system. Allowing readers to better learn via case-based examples, this practical volume depicts real examples of decisions neuroscientists and neurosurgeons need to make every day from leaders in the field.

This book serves as a companion text to the editor’s previous titles Essential Neuromodulation and Innovative Neuromodulation for neuroscience, neural engineering, and biomedical engineering courses.


About the Author

Jeff Arle, MD, PhD, FAANS

Dr. Arle is currently the Associate Chief of Neurosurgery at Beth Israel Deaconess Medical Center in Boston, the Chief of Neurosurgery at Mt. Auburn Hospital in Cambridge, and an Associate Professor of Neurosurgery at Harvard Medical School. He received his BA in Biopsychology from Columbia University in 1986 and his MD and PhD from the University of Connecticut in 1992. His dissertation work for his doctorate in Biomedical Sciences was in computational modeling in the Cochlear Nucleus. He then went on to do a residency in neurosurgery at the University of Pennsylvania, incorporating a double fellowship in movement disorder surgery and epilepsy surgery under Drs. Patrick Kelly, Ron Alterman, and Werner Doyle, finishing in 1999.

He edited the companion text Essential Neuromodulation with Dr. Shils, the first edition published by Elsevier in 2011. He has now practiced in the field of functional neurosurgery for 17 years and is experienced in all areas of neuromodulation from deep brain stimulators to vagus nerve, spinal cord, peripheral nerve, and motor cortex stimulators, contributing frequent peer-reviewed publications and numerous chapters to the literature on many aspects of the neuromodulation field. He currently serves as an associate editor at the journals Neuromodulation and Neurosurgery, is the co-chair of the Research and Scientific Policy Committee for the International Neuromodulation Society, and is on the Board of Directors for the International Society for Intraoperative Neurophysiology. His long-standing research interests are in the area of computational modeling in the understanding and improved design of devices used in neuromodulation treatments.

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