Sang Heon Lee

Size and Aggregation of Corticosteroids Used for Epidural Injections

OBJECTIVEnThe purpose of this study was to document particulate size in commonly used corticosteroid preparations. Inadvertent injection of particulate corticosteroids into a vertebral or foraminal artery can cause brain and spinal cord embolic infarcts and the size of the particles could be directly related to the chance that a clinically significant infarct would occur. One might assume that corticosteroids with particles significantly smaller than red blood cells might be safer.nnnDESIGNnThe following four types of corticosteroid preparations were used in various solutions and evaluated under light microscopy: dexamethasone sodium phosphate injection, triamcinolone acetonide injectable suspension, betamethasone sodium phosphate and betamethasone acetate injectable suspension, and methylprednisolone acetate injectable suspension.nnnRESULTSnDexamethasone sodium phosphate particle size was approximately 10 times smaller than red blood cells and the particles did not appear to aggregate; even mixed with 1% lidocaine HCl solution and with contrast dye, the size of the particles were unchanged. Triamcinolone acetonide and betamethasone sodium phosphate showed variable sizes; some particles were larger than red blood cells, and aggregation of particles was evident. Methylprednisolone acetate showed uniformity in size and the majority were smaller than red blood cells which were not aggregated, but the particles were densely packed.nnnCONCLUSIONSnCompared with the particulate steroid solutions, dexamethasone sodium phosphate had particles that were significantly smaller than red blood cells, had the least tendency to aggregation, and had the lowest density. These characteristics should significantly reduce the risk of embolic infarcts or prevent them from occurring after intra-arterial injection. Until shown otherwise in clinical studies, interventionalists might consider using dexamethasone or another corticosteroid preparation with similar high solubility and negligible particle size when performing epidural injections.

Efficacy of a New Navigable Percutaneous Disc Decompression Device (L'DISQ) in Patients with Herniated Nucleus Pulposus Related to Radicular Pain

STUDY DESIGNnAn institutional, prospective clinical data analysis.nnnOBJECTIVEnTo evaluate the safety and efficacy of a new navigable percutaneous disc decompression device (LDISQ) in patients with lumbar disc herniation with radicular pain.nnnMETHODS AND OUTCOME MEASURESnWe performed disc decompressions using LDISQ on 27 patients with persistent disabling back and leg pain for 1 month or longer (average 6.48 months) due to a herniated lumbar intervertebral disc. Baseline data were prospectively gathered before the index procedure and at 1, 4, 12, and 24 weeks post-procedure. Data included pain intensity (visual analog scale [VAS]), measure of disability (Oswestry Disability Index [ODI] and Rolando-Morris Questionnaire [RM]), health-related quality of life (Bodily Pain Scale of Short Form-36 version 2 [SF-36 BP]), and passive straight leg raising test (SLR).nnnRESULTSnThe VAS fell from 7.08±1.22 to 1.84±0.99 scores at 24 weeks post-procedure. At 24 weeks, the ODI had fallen from 41.88±10.61 to 16.66±8.55% and the RM from 11.52±3.91 to 2.68±1.97 points. The SF-36 BP dropped significant improvement from 32.89±5.83 to 49.57±4.96 scales. In the SLR test, the angular change of 24 weeks showed considerable improvement from 60.20±20.02 to 83.00±14.29 degrees. No major complication occurred, although two cases developed a disc reherniation 1 month post-procedure.nnnCONCLUSIONSnThe LDISQ device is specifically designed to remove herniated disc using a wand that can be navigated into a disc protrusion or extrusion. Following decompression, we measured clinically significant pain improvement and decreased disability for patients with both radicular and axial pain caused by protruded and extruded discs.

Toward More Useful Pressure-Controlled Discography: In Vitro Evaluation of Injection Speed, Sensor Location, and Tube Length

OBJECTIVEnPressure-controlled manometric discography is used by clinicians to evaluate discogenic pain. However, some would improve diagnostic accuracy. The goal of this study was to investigate potential confounding factors that might affect discographic results. Pressure differences depending on different speed of injection, lengths of connecting tubing and locations of sensors were evaluated using an in vitro model system.nnnMETHODSnTwo sets of automated discography devices were arranged to record post-syringeal pressure pressures (PSPs) and intradiscal pressures (IDPs) in an air chamber disk model representing intradiscal pressure. PSPs and IDPs were measured simultaneously while varying injection speeds, and using intrasyringeal and extrasyringeal pressure sensors and contrast medium-filled tubing of different lengths. All pressure/volume curves were collected and viewed dynamically, and stored for further analysis.nnnRESULTSnAt injection speed of 0.1 cc/second, the mean pressure difference (mean ΔP) between PSP and IDP was 38.1 psi. As injection speed was reduced, mean ΔP was proportionally decreased. Mean ΔP was 5.3 psi at injection speed of 0.01 cc/second and 0.7 psi at 0.005 cc/second. Mean ΔP values were significantly higher when pressures were recorded using intrasyringeal sensor: at injection speed of 0.1 cc/second, PSP and IDP values were 82.9 and 30.1 psi, respectively, compared with 50.6 and 12.5 psi measured by extrasyringeal sensor. Mean ΔP due to increased length of tubing was not significant.nnnCONCLUSIONnDiscography can be better performed with low speed injection (≤0.01 cc/second), using an extrasyringeal sensor. Difference of length of connecting tubings did not cause significant pressure differences. These data suggest that automated discography is a helpful adjunct to improve diagnostic accuracy, due to extrasyringeal location of pressure sensor and greater control of injection speed.

Echotexture and correlated histologic analysis of peripheral nerves important in regional anesthesia.

Background and Objectives: Peripheral nerves in different body locations display different echotextures on ultrasound imaging, and knowledge of peripheral nerve echotexture is helpful for locating target nerves. However, the degree of echogenicity is often difficult to characterize. We aimed to define objectively the degree of echogenicity of peripheral nerves using grayscale measurements and compare nerve echotexture with matched histologic samples. Methods: Ultrasound images of peripheral nerves in 12 body locations were obtained in 20 healthy subjects using linear 8- to 12-MHz and curved 3- to 5-MHZ transducers. Corresponding nerve segments from 2 cadavers were imaged in vitro before they were sectioned for histologic examination. Nerve echogenicity was assessed by an objective grayscale (G) and a subjective echogenicity index (SEI) determined by experienced evaluators. The results of G and SEI in selected peripheral nerves were compared and correlated with histologic morphometry. Results: There is a close correlation between SEI and G (P < 0.05). Mixed echogenicity was seen in 30% of the peripheral nerves; 25.4% were predominantly hypoechogenic, and 44.5% hyperechogenic. Nerves in the neck and upper arm are more frequently hypoechoic, whereas those in the leg are more frequently hyperechoic. Histologically, differences in echogenicity are dependent on fascicle diameter and on nerve fascicular pattern, that is, differing ratios of fascicle number to total nerve area. Conclusions: This study suggests that grayscales can be used to objectively determine echogenicity and shows that grayscale measurements match well with subjective visual grading. Histologic analysis showed that both ratio of total fascicular area to whole nerve area and fascicular pattern are important determinants of echogenicity.

An Assessment of a New Navigatable Percutaneous Disc Decompression Device (L'DISQ) Through Histologic Evaluation and Thermo-Mapping in Human Cadaveric Discs

STUDY DESIGNnThis is an in vitro experimental study of the technical capability and safety study of a navigable percutaneous disc decompression device named LDISQ.nnnOBJECTIVESnThe objectives of this study were to determine if LDISQ could adequately reach certain target zones in the disc and to measure the distribution of rises in temperature in the surrounding tissue when the device was used to ablate the disc.nnnMETHODSnPlacement of the wand of LDISQ was attempted into the posterior annulus of the discs of four fresh human cadavers. During disc ablation, thermocouple probes were used to measure the temperature within the nucleus pulposus and annulus fibrosus, on the surface of the annulus, and on the posterior longitudinal ligament. Tissues harvested from around the disc were examined histologically.nnnRESULTSnThe tip of the wand could be successfully navigated to the posterolateral or posterocentral annulus at all levels above L5-S1 using a lateral approach. Rises in temperature did not exceed 13.25 ± 0.84°C within the disc, and did not exceed 1°C on the surface of the disc. Histology demonstrated no thermal damage to the surrounding neural tissues.nnnCONCLUSIONnLDISQ can be successfully navigated to the target zones, and disc tissue ablated without thermal or structural damage to the adjacent neural tissues.

Effectiveness of a New Navigable Percutaneous Disc Decompression Device (L'DISQ) in Patients with Lumbar Discogenic Pain

OBJECTIVEnThis study is a pilot study to assess the clinical outcomes of percutaneous disc decompression using the LDISQ in patients with lumbar discogenic pain.nnnSTUDY DESIGNnAn institutional, prospective clinical data analysis.nnnMETHODSnWe ablated the torn annulus using LDISQ on 20 patients with axial low back pain for at least 3 months (average 29 months) unresponsive to conservative management. Before the therapeutic procedure, all the patients had been diagnosed with lumbar discogenic pain through provocation discography, which had confirmed the level of painful discs. The torn annulus was identified through lumbosacral magnetic resonance image and computed tomographic discogram. Baseline data were prospectively gathered before the procedure and at 1, 4, 12, 24, and 48 weeks post-procedure. Data included pain intensity (visual analog scale [VAS]), measure of disability (Oswestry Disability Index [ODI] and Rolando-Morris Disability Questionnaire [RM]), and health-related quality of life (Bodily Pain Scale of Short Form-36 version 2 [SF-36 BP]).nnnRESULTSnAt 48 weeks, the VAS fell from 7.55u2009±u20091.28 to 3.60u2009±u20092.28 scores, the ODI and RM had decreased significantly, and the SF-36 BP showed significant improvement (Pu2009<u20090.05). The success rates of procedure were 55.0% at 48 weeks. There were no complications with the exception of a minor venous bleeding at the site of needle puncture.nnnCONCLUSIONSnThe LDISQ device is specifically designed to ablate adjacent disc tissue using a wand that can be navigated into a torn annulus. Following ablation, we measured clinically significant pain improvement and decreased disability for patients with axial low back pain.

Feasibility of Navigable Percutaneous Disk Decompressor (L'DISQ-C) for Cervical Disk Herniation

Objective To assess the procedural efficacy and safety of a Navigable Percutaneous Disk Decompressor (LDISQ‐C) for cervical disk herniation. Methods We performed intradiskal decompression on cervical spine specimens from five human cadavers using the LDISQ‐C under C‐arm fluoroscopic guidance. We evaluated our success for positioning the navigable wand tip into the target region and recorded temperature variation at various distances from the wand tip in the cervical nucleus pulposus. The histologic effect of plasma decompression was examined microscopically using harvested tissues adjacent to the procedure site. Results We successfully navigated the tip of the LDISQ‐C into the target region of the posterior cervical disks on the first insertion attempt in all C3‐C4 to C6‐C7 disks and in 50% of the C2‐C3 and C7‐T1 disks. The average temperature elevations within the nucleus pulposus ranged from 4.14 ± 0.08°C to 12.17 ± 0.76°C at various distances from the wand tip with or without saline infusion. A histologic examination showed only minor denaturation at the marginal border of the procedure tract. Conclusion We effectively navigated the LDISQ‐C wand tip into the posterior target region of six cadaveric cervical disks and performed percutaneous resection of the target disk tissues without significant thermal or structural damage to adjacent tissues.

Optimal Parameters for Intervertebral Disk Resection Using Aqua-Plasma Beams

Objective A minimally invasive procedure for intervertebral disk resection using plasma beams has been developed. Conventional parameters for the plasma procedure such as voltage and tip speed mainly rely on the surgeons personal experience, without adequate evidence from experiments. Our objective was to determine the optimal parameters for plasma disk resection. Methods Rate of ablation was measured at different procedural tip speeds and voltages using porcine nucleus pulposi. The amount of heat formation during experimental conditions was also measured to evaluate the thermal safety of the plasma procedure. Results The ablation rate increased at slower procedural speeds and higher voltages. However, for thermal safety, the optimal parameters for plasma procedures with minimal tissue damage were an electrical output of 280 volts root‐mean‐square (Vrms) and a procedural tip speed of 2.5 mm/s. Conclusion Our findings provide useful information for an effective and safe plasma procedure for disk resection in a clinical setting.