Predictors of Skip Laminotomy for Placement of Paddle Leads for Spinal Cord Stimulation

OBJECTIVES

Placement of a standard paddle lead for spinal cord stimulation (SCS) requires a laminotomy for positioning of the lead within the epidural space. During initial placement, an additional laminotomy or laminectomy, termed a "skip" laminotomy, may be necessary at a higher level to pass the lead to the appropriate midline position. Patient and radiographic factors that predict the need for a skip laminotomy have yet to be identified.

MATERIALS AND METHODS

Participants who underwent SCS paddle placement at Albany Medical Center between 2016 and 2017 were identified. Operative reports were reviewed to identify the paddle type, level of initial laminotomy, target level, and skip laminotomy level. Preoperative thoracic magnetic resonance images (MRIs) were reviewed, and spinal canal diameter, interpedicular distance, and dorsal cerebral spinal fluid thickness were measured for each participant when available.

RESULTS

A total of 106 participants underwent thoracic SCS placement. Of these, 97 had thoracic MRIs available for review. Thirty-eight participants required a skip laminotomy for placement of the paddle compared with 68 participants who did not. There was no significant difference in demographic features including age, sex, body mass index, and surgical history. Univariate analyses that suggested trends were selected for further analysis using binary logistic regression. Level of initial laminotomy (odds ratio [OR] = 1.51, p = 0.028), spinal canal diameter (OR = 0.71, p = 0.015), and dorsal cerebrospinal fluid thickness (OR = 0.61, p = 0.011) were correlated with skip laminotomy. Target level (OR = 1.27, p = 0.138) and time from trial (1.01, p = 0.117) suggested potential association. The multivariate regression was statistically significant, X2(10) = 28.02, p = 0.002. The model explained 38.3% of the variance (Nagelkerke R2) and predicted skip laminectomy correctly in 73.3% of cases. However, for the multivariate regression, only a decrease in spinal canal diameter (OR = 0.59, p = 0.041) was associated with a greater odds of skip laminotomy.

CONCLUSIONS

This study aims to characterize the patient and radiographic factors that may predict the need to perform a skip laminotomy during the initial placement of SCS paddles. Here, we show that radiographic and anatomic variables, primarily spinal canal diameter, play an important role in predicting the need for a skip laminotomy. Furthermore, we suggest that target level for placement and level of initial laminotomy also may contribute. Further investigation of the predictive factors for performing a skip laminotomy would help optimize surgical planning and preoperative patient selection and counseling.

Interlaminar endoscopic uniportal approach for implantation of a paddle lead larger than 10 mm for spinal cord stimulation: illustrative case

BACKGROUND

The authors aim to describe a new technique for implantation of a spinal cord stimulation paddle lead sized over 10 mm through an endoscopic uniportal approach. A new endoscopic cannula was developed for the passage of a paddle lead width between 10 and 13 mm. The distal portion of the cannula was designed with a larger opening, providing better visibility of the anterior portion of the adjacent structures, thus allowing a panoramic view of the electrode passage. An electrode was implanted in an 11-mm paddle.

OBSERVATIONS

After searching PubMed, Cochrane, and Lilacs databases, the authors found no mention of the implantation of a paddle electrode with a width greater than 10 mm. The implantation of a paddle electrode less than 10 mm wide is possible via endoscopic access using 10-mm working channels. However, for electrodes with a width greater than 10 mm, access via endoscopy is impossible, since the working channel is only 10 mm.

LESSONS

The authors concluded that it is possible to pass electrodes safely and effectively with a paddle width between 10 and 13 mm using spinal endoscopy via uniportal interlaminar access. However, it is necessary to expand studies to elucidate this technique of endoscopic implantation of electrodes for neurostimulation.

Spinal Cord Stimulation for Neuropathic Pain following a Spinal Cord Lesion with Past Spinal Surgical Histories Using a Paddle Lead Placed on the Rostral Side of the Lesion: Report of Three Cases

Spinal cord parenchymal lesions may induce intractable neuropathic pain. However, the efficacy of conventional spinal cord stimulation for the neuropathic pain following spinal cord lesions remains to be controversial. In this study, we present three cases of spinal cord stimulation using a paddle lead at the rostral side of the spinal lesion causing pain symptoms. Good pain reductions were achieved using conventional stimulation in one case and using differential target multiplexed stimulation in two cases. Case 1: A 55-year-old man presented with neuropathic pain affecting his bilateral upper extremities due to a traumatic cervical spinal cord injury. Conventional stimulation via a paddle-type electrode was able to reduce the pain from 8 to 4 via a visual analog scale. Case 2: A 67-year-old man had undergone three spinal surgeries. He presented with pain and numbness of bilateral lower extremities due to a spinal cord lesion by thoracic disc herniation. Differential target multiplexed stimulation via a paddle-type electrode achieved excellent pain reduction, that is, from 9 to 2 on the visual analog scale. Case 3: An 80-year-old man presented with pain in his bilateral upper extremities due to a cervical spinal cord lesion caused by compression and spinal canal stenosis. Posterior cervical decompression and paddle-type electrode placement were performed simultaneously. Differential target multiplexed stimulation was able to achieve excellent pain reduction, from 7 to 2 on the visual analog scale. Spinal cord stimulation using a paddle lead at the rostral side of the spinal lesion and differential target multiplexed stimulation may provide significant opportunities for patients with intractable neuropathic pain following spinal cord lesions.

Porous extraction paddle: a solid-phase extraction technique for studying the urine metabolome

RATIONALE

A method was needed to accomplish solid-phase extraction of a large urine volume in a convenient way where resources are limited, towards a goal of metabolome and xenobiotic exposome analysis at another, distant location.

METHODS

A porous extraction paddle (PEP) was set up, comprising a porous nylon bag containing extraction particles that is flattened and immobilized between two stainless steel meshes. Stirring the PEP after attachment to a shaft of a motor mounted on the lid of the jar containing the urine accomplishes extraction. The bag contained a mixture of nonpolar and partly nonpolar particles to extract a diversity of corresponding compounds.

RESULTS

Elution of a urine-exposed, water-washed PEP with aqueous methanol containing triethylammonium acetate (conditions intended to give a complete elution), followed by MALDI-TOF/TOF-MS, demonstrated that a diversity of compounds had been extracted ranging from uric acid to peptides.

CONCLUSIONS

The PEP allows the user to extract a large liquid sample in a jar simply by turning on a motor. The technique will be helpful in conducting metabolomics and xenobiotic exposome studies of urine, encouraging the extraction of large volumes to set up a convenient repository sample (e.g. 2 g of exposed adsorbent in a cryovial) for shipment and re-analysis in various ways in the future, including scaled-up isolation of unknown chemicals for identification. Copyright © 2016 John Wiley & Sons, Ltd.

Choreographed swimming of copepod nauplii

Small metazoan paddlers, such as crustacean larvae (nauplii), are abundant, ecologically important and active swimmers, which depend on exploiting viscous forces for locomotion. The physics of micropaddling at low Reynolds number was investigated using a model of swimming based on slender-body theory for Stokes flow. Locomotion of nauplii of the copepod Bestiolina similis was quantified from high-speed video images to obtain precise measurements of appendage movements and the resulting displacement of the body. The kinematic and morphological data served as inputs to the model, which predicted the displacement in good agreement with observations. The results of interest did not depend sensitively on the parameters within the error of measurement. Model tests revealed that the commonly attributed mechanism of 'feathering' appendages during return strokes accounts for only part of the displacement. As important for effective paddling at low Reynolds number is the ability to generate a metachronal sequence of power strokes in combination with synchronous return strokes of appendages. The effect of feathering together with a synchronous return stroke is greater than the sum of each factor individually. The model serves as a foundation for future exploration of micropaddlers swimming at intermediate Reynolds number where both viscous and inertial forces are important.

Electrostatic interaction between dipoles and side chains in the voltage sensor domain of K(+) channel

Background:

It is well known that α-helices of protein, possessing equal and opposite charged ends, behaves like a macrodipole, but the relative importance of such macrodipoles to the aggregation of a pair of helix in the voltage sensor domain (VSD) of K+ ion channel, has not been assessed. In the VSD, importance has been given primarily to the helically arranged Arginine residues of helix, but the role of the charged residues of S3b is less focused.

Method and Objective:

Applying electrostatic theory, we have studied the interaction between the charges of S3b-S4 α-helix pair of KvAP through virtual mutagenesis.

Result and Conclusion:

We have shown that the terminal charges arising from the inherent dipolar property of α-helices play an important role in affecting the stability of the S3b-S4 pair, and in determining its spatial position at zero transmembrane potential. Moreover, the negatively charged side chain of S3b was found to be the primary stabilizing factor in holding S3b-S4 pair together as a “paddle”. Comparison of sequences of S3b helix of K+ channels from different species showed a previously unreported positional conservation of negative residues, highlighting their functional importance. These charges may contribute to the energetic of α-helix movements in an electric field.