Distance to the Adult Cervical Epidural Space:

Cervical Epidural Depth: Correlation Between Cervical MRI Measurements of the Skin-to-Cervical Epidural Space and the Actual Needle Depth During Interlaminar Cervical Epidural Injections

Objective

The purpose of this study was to assess the correlation between skin-to-epidural space depth, as measured on cervical magnetic resonance imaging (MRI), and actual needle depth, as measured by Tuohy needle markings during cervical epidural steroid injections.

Methods

We conducted a retrospective review of cervical MRI images to determine estimated depth from skin to epidural space. Of the 121 reviewed patients who underwent cervical epidural steroid injections, 81 met inclusion criteria and were retained for data analysis.

Results

At the C6-C7 level, the estimated needle depth according to MRI images was 6.03 ± 1.15 cm (mean ± SD) and the actual needle depth was 5.62 ± 0.77 cm. At the C7-T1 level, the estimated needle depth based on MRI images was 5.90 ± 1.05 cm and the actual needle depth was 5.73 ± 0.98 cm. At both C6-C7 and C7-T1, MRI depth (P < 0.009, P < 0.001) and body mass index (P < 0.001, P < 0.002) were significantly associated with actual depth.

Conclusions

Estimates of needle depth made with MRI were consistently slightly deeper than the actual loss-of-resistance needle depth, indicating that the provider should employ caution when using MRI predictive depths. Information garnered from preprocedure MRIs can be used to improve the safety of cervical epidural steroid injection procedures.

Is There a Relationship Between Body Mass Index and Fluoroscopy Time During Cervical Interlaminar Epidural Steroid Injections?

Background

The challenge of obtaining medical imaging in individuals with higher body mass index (BMI) is described, but there is minimal data regarding the relationship between BMI and fluoroscopy time during cervical interlaminar epidural steroid injection (CIESI).

Objective

To determine the relationship between BMI and fluoroscopy time during CIESI.

Methods

Retrospective cohort study of patients who underwent fluoroscopically guided CIESI between January 2014 and February 2015 at an academic pain medicine center. Fluoroscopy time data were collected. Comparisons based on analysis of variance were made between patients with normal (<25.0 kg/m 2 ), overweight (25.0-29.9 kg/m 2 ), and obese (≥30.0 kg/m 2 ) BMI.

Results

Of 399 procedure encounters, 366 had documented BMI and fluoroscopy time data and were included for analysis. Mean age (± SD) in this cohort was 53 ± 13 years, including 189 females (52%) and 205 first-time injections. Mean fluoroscopy time for all injections was 18 ± 10 seconds. Separated by categorical BMI class, the mean fluoroscopy time was 18 ± 9 seconds for normal weight patients, 17 ± 10 seconds for overweight patients, and 20 ± 11 seconds for obese patients, respectively. Post hoc analysis showed that fluoroscopy time was significantly longer only in obese compared with overweight patients ( P  = 0.02). Trainee involvement and first-time vs repeat injection did not significantly alter fluoroscopy time ( P  = 0.17 and P  = 0.12, respectively).

Conclusions

The findings of this study indicate that BMI does not appear to have a clinically significant impact on fluoroscopy time during cervical interlaminar epidural steroid injection procedures. Future study is needed to directly quantify radiation exposure in patients and practitioners, as well as the associated health risk.

Polydimethylsiloxane-based optical waveguides for tetherless powering of floating microstimulators

Neural electrodes and associated electronics are powered either through percutaneous wires or transcutaneous powering schemes with energy harvesting devices implanted underneath the skin. For electrodes implanted in the spinal cord and the brain stem that experience large displacements, wireless powering may be an option to eliminate device failure by the breakage of wires and the tethering of forces on the electrodes. We tested the feasibility of using optically clear polydimethylsiloxane (PDMS) as a waveguide to collect the light in a subcutaneous location and deliver to deeper regions inside the body, thereby replacing brittle metal wires tethered to the electrodes with PDMS-based optical waveguides that can transmit energy without being attached to the targeted electrode. We determined the attenuation of light along the PDMS waveguides as 0.36 ± 0.03 ?? dB / cm and the transcutaneous light collection efficiency of cylindrical waveguides as 44 % ± 11 % by transmitting a laser beam through the thenar skin of human hands. We then implanted the waveguides in rats for a month to demonstrate the feasibility of optical transmission. The collection efficiency and longitudinal attenuation values reported here can help others design their own waveguides and make estimations of the waveguide cross-sectional area required to deliver sufficient power to a certain depth in tissue.

Cervical epidural analgesia in current anaesthesia practice: systematic review of its clinical utility and rationale, and technical considerations

Cervical epidural analgesia (CEA) is an analgesic technique, potentially useful for surgeries involving the upper body. Despite the inherent technical risks and systemic changes, it has been used for various surgeries. There have been no previously published systematic reviews aimed at assessing its clinical utility. This systematic review was performed to explore the perioperative benefits of CEA. The review was also aimed at identifying the rationale of its use, reported surgical indications and the method of use. We performed a literature search involving PubMed and Embase databases, to identify studies using CEA for surgical indications. Out of 467 potentially relevant articles, 73 articles were selected. Two independent investigators extracted data involving 5 randomized controlled trials, 17 observational comparative trials, and 51 case reports (series). The outcomes studied in most comparative studies were on effects of local anaesthetics and other agents, systemic effects, and feasibility of CEA. In one randomized controlled study, CEA was observed to decrease the resting pain scores after pharyngo-laryngeal surgeries. In a retrospective study, CEA was shown to decrease the cancer recurrence after pharyngeal-hypopharyngeal surgeries. The limited evidence, small studies, and the chosen outcomes do not allow for any specific recommendations based on the relative benefit or harm of CEA. Considering the potential for significant harm, in the face of better alternatives, its use must have a strong rationale mostly supported by unique patient and surgical demands. Future studies must aim to assess analgesic comparator effectiveness for clinically relevant outcomes.

Cervical epidural steroid injections for the treatment of cervical spinal (neck) pain

Cervical epidural steroid injections (CESI) are an accepted treatment for neck pain with a radicular component, and may be accomplished by using either transforaminal (CTFESI) or interlaminar (CILESI) approaches. CESIs are routinely performed using real-time fluoroscopic-guidance in conjunction with the injection of water soluble, iodine-based contrast media to enhance visualization of intravascular injections. Digital subtraction angiography (DSA) imaging is an adjuvant to fluoroscopic methods for visualizing blood vessels while performing spinal injections. However, as with any neuraxial procedure, various complications associated with CESIs have been reported. Complications are directly associated with the technical procedures of CESIs. Particulate steroids may have a prolonged duration of action but non-particulate steroids are safer for CESIs. Blunt-beveled needles are less likely than sharp-beveled needles to penetrate blood vessels to cause bleeding complications during CTFESI procedures. Small doses of local anesthetics appear to be safe and assist in identifying intravascular injections previously overlooked by conventional techniques.

An alternative approach to needle placement in cervicothoracic epidural injections

The use of fluoroscopy guidance together with the loss of resistance technique during epidural injections has been advocated lately; moreover, epidural injections in the absence of fluoroscopic guidance have a high rate of inaccurate needle-tip placement during the injections. However, the approach to the lower cervical and upper thoracic epidural space may be challenging due to its obscure lateral fluoroscopic views from overlying normal tissue structures. In this case, we report an alternative oblique C-arm fluoroscopy guided view approach to supplement the standard anterior-posterior and lateral fluoroscopic views to facilitate successful needle placement and precise anatomical localization of the epidural space.

Cervical epidural depth: correlation between needle angle, cervical anatomy, and body surface area

OBJECTIVES

Prior to performing a cervical interlaminar epidural steroid injection (CIESI), knowledge of the depth from lamina to epidural space may assist in preventing cord injury.

METHODS

This is a prospective analysis of data including gender, age, weight, height, previous surgery, neck circumference, distances from tip of chin to sternal notch, occiput to C7 vertebral prominence, and ear lobe to tip of shoulder, pain score, angle from C7 vertebral prominence to the back, depth at which the Tuohy needle contacted T1 vertebral lamina and depth at which the epidural space was entered was conducted with 92 subjects, average age (± standard deviation [SD]) 41.3 ± 13.2 years underwent fluoroscopically guided C7-T1 intralaminar epidural steroid injections.

RESULTS

Depth to lamina was the best individual predictor with an r value of 0.86. Weight, neck circumference, and body mass index (BMI) positively correlated with depth to epidural space with r values of 0.66, 0.62, and 0.61, respectively. A linear regression model of depth to lamina for predicting depth to epidural space was accurate to within ± 0.5 cm of the actual depth in 69% of subjects. However, when comparing predicted with actual depth to epidural space for individual subjects, the prediction was inaccurate by as much as 1.6 cm deep or 1.7 cm shallow.

CONCLUSIONS

While statistically significant correlations do exist between both quantitative external body characteristics and depth to cervical epidural space and T1vertebral lamina to depth of cervical epidural space for fluoroscopically guided interlaminar epidural steroid injections at C7-T1, even the most optimal regression models do not permit clinical confidence in predicted depth to epidural space.

The "swimmer's view" as alternative when lateral view is inadequate during interlaminar cervical epidural steroid injections

OBJECTIVE

To present a technique that better visualizes the needle during interlaminar cervical epidural steroid injection (ICESI) in patients where the lateral view is inadequate.

DESIGN

Case report.

SETTING

Private group practice.

SUBJECT

A 57-year-old morbidly obese male presenting for ICESI for left neck and upper limb pain after a motor vehicle accident. Magnetic resonance imaging revealed left C6-7 herniated nucleus pulposis and C4-5 osteophytic disc-ridge complex. Electrodiagnostic evaluation revealed activity consistent with a left C7 radiculopathy.

INTERVENTION

Left C7-T1 ICESI. Needle was obscured in the lateral view by the patient's shoulders. Needle was made visible by positioning the patient for Swimmer's view.

RESULTS

Full resolution of symptoms without associated complications.

CONCLUSIONS

Grave complications have been associated with ICESI necessitating impeccable and systematic technique with substantial knowledge of anatomy. Although injection at lower levels is advocated for safety concerns, the needle during lateral view may be obscured by the shoulders in some patients. The "Swimmer's View" position may be attempted when lateral view is insufficient to visualize needle during ICESI.

A prospective, observational study of the relationship between body mass index and depth of the epidural space during lumbar transforaminal epidural steroid injection

BACKGROUND AND OBJECTIVES

Previous studies have concluded that transforaminal epidural steroid injections (ESIs) are more effective than interlaminar injections in the treatment of radiculopathies due to lumbar intervertebral disk herniation. There are no published studies examining the depth of epidural space using a transforaminal approach. We investigated the relationship between body mass index (BMI) and the depth of the epidural space during lumbar transforaminal ESIs.

METHODS

Eighty-six consecutive patients undergoing lumbar transforaminal ESI at the L3-L4, L4-L5, and L5-S1 levels were studied. Using standard protocol, the foraminal epidural space was attained using fluoroscopic guidance. The measured distance from needle tip to skin was recorded (depth to foraminal epidural space). The differences in the needle depth and BMI were analyzed using regression analysis.

RESULTS

Needle depth was positively associated with BMI (regression coefficient [RC], 1.13; P < 0.001). The median depths (in centimeters) to the epidural space were 6.3, 7.5, 8.4, 10.0, 10.4, and 12.2 for underweight, normal, preobese, obese I, obese II, and obese III classifications, respectively. Sex (RC, 1.3; P = 0.02) and race (RC, 0.8; P = 0.04) were also significantly associated with needle depth; however, neither factor remained significant when BMI was accounted as a covariate in the regression model. Age, intervertebral level treated, and oblique angle had no predictive value on foraminal depth (P > 0.2).

CONCLUSION

There is a positive association between BMI and transforaminal epidural depth, but not with age, sex, race, oblique angle, or intervertebral level.

Complications of interlaminar cervical epidural steroid injections: a review of the literature

STUDY DESIGN

A comprehensive literature review.

OBJECTIVES

To review and critically evaluate the past literature focusing on incidence and clinical presentation of complications associated with interlaminar cervical epidural steroid injection (ICESI). The overall goal is to guide the direction of future research and improve clinical care by increasing awareness of complications, their presentations, and management.

SUMMARY OF BACKGROUND DATA

Although ICESI is considered a relatively safe procedure, a number of minor and major complications have been reported across the literature. Thus far, reports of complications are limited to retrospective studies, case reports, and data extrapolated from lumbar and thoracic procedures. As a result, the past literature has been of limited value with regard to facilitating both clinical care and future research efforts.

METHODS

Medical databases were searched for studies of ICESI. The bibliographies of these papers were then searched as well. Papers focusing on cervical techniques that did not involve injection into the epidural space were discarded, as were studies of thoracic and lumbar spine injections. Reports of complications associated with ICESI were further subdivided into major and minor categories.

RESULTS

The reported rate of complications associated with ICESI varied between 0 and 16.8%.

CONCLUSION

There are significant limitations in the available literature discussing the complications associated with ICESI, but they strongly suggest that ICESI is a relatively safe procedure. Numerous potential adverse reactions have been associated with ICESI, with the vast majority being minor and transient in nature. However, serious complications may also result and may be technique related. Injectionists should be aware of the clinical presentations, rates, potential consequences, and appropriate techniques to avoid these complications. More studies are needed with specific focus on cervical complication rates, standardization of injection techniques, and differentiation between complications and poor efficacy. In addition, the use of a prospective randomized blinded controlled design would be beneficial.