A prospective, randomized, multicenter study of intraosseous basivertebral nerve ablation for the treatment of chronic low back pain.

BACKGROUND CONTEXT: Current literature suggests that degenerated or damaged vertebral endplates are a significant cause of chronic low back pain (LBP) that is not adequately addressed by standard care. Prior 2-year data from the treatment arm of a sham-controlled randomized controlled trial (RCT) showed maintenance of clinical improvements at 2 years following radiofrequency (RF) ablation of the basivertebral nerve (BVN). PURPOSE: The purpose of this RCT was to compare the effectiveness of intraosseous RF ablation of the BVN to standard care for the treatment of chronic LBP in a specific subgroup of patients suspected to have vertebrogenic related symptomatology. STUDY DESIGN/SETTING: A prospective, parallel, open label RCT was conducted at 20 U.S. sites. PATIENT SAMPLE: A total of 140 patients with chronic LBP of at least 6 months duration, with Modic Type 1 or 2 vertebral endplate changes between L3 and S1, were randomized 1:1 to undergo either RF ablation of the BVN or continue standard care. OUTCOME MEASURES: Oswestry Disability Index (ODI) was collected at baseline, 3, 6, 9, and 12-months postprocedure. Secondary outcome measures included a 10-point Visual Analog Scale (VAS) for LBP, ODI and VAS responder rates, SF-36, and EQ-5D-5L. The primary endpoint was a between-arm comparison of the mean change in ODI from baseline to 3 months post-treatment. METHODS: Patients were randomized 1:1 to receive RF ablation or to continue standard care. Self-reported patient outcomes were collected using validated questionnaires at each study visit. An interim analysis to assess for superiority was prespecified and overseen by an independent data management committee when a minimum of 60% of patients had completed their 3-month primary endpoint visit. RESULTS: The interim analysis showed clear statistical superiority (p<.001) for all primary and secondary patient-reported outcome measures in the RF ablation arm compared with the standard care arm. This resulted in a data management committee recommendation to halt enrollment in the study and offer early cross-over to the control arm. These results are comprised of the outcomes of the 104 patients included in the intent-to-treat analysis of the 3-month primary endpoint, which included 51 patients in the RF ablation arm and 53 patients in the standard care arm. Baseline ODI was 46.1, VAS was 6.67, and mean age was 50 years. The percentage of patients with LBP symptoms ≥5 years was 67.3%. Comparing the RF ablation arm to the standard care arm, the mean changes in ODI at 3 months were -25.3 points versus -4.4 points, respectively, resulting in an adjusted difference of 20.9 points (p<.001). Mean changes in VAS were -3.46 versus -1.02, respectively, an adjusted difference of 2.44 cm (p<.001). In the RF ablation arm, 74.5% of patients achieved a ≥10-point improvement in ODI, compared with 32.7% in the standard care arm (p<0.001). CONCLUSIONS: Minimally invasive RF ablation of the BVN led to significant improvement of pain and function at 3-months in patients with chronic vertebrogenic related LBP.

Electrical Impedance Myography for Assessing Paraspinal Muscles of Patients with Low Back Pain.

The objective of this study was to determine the potential value of electrical impedance myography (EIM) for assessing lumbosacral paraspinal muscle (LPM) condition in lower back pain (LBP) patients. Standard methods for assessing the condition of LPMs, such as magnetic resonance imaging, are inconvenient and expensive. One tool that could be useful for this purpose is electrical impedance myography (EIM) a technique that can be performed rapidly at the bedside. After undergoing a screening history and examination, subjects were studied with the mView EIM device (Myolex, Inc, Boston). Bilateral LPMs were measured three times each and the two closest sets of measurements averaged on each side. Data analysis included non-parametric two-group comparisons between healthy subjects and back pain patients, receiver-operating curve analyses, and correlation analyses to age and body mass index. A total of 86 healthy individuals (median age (interquartile range) (IQR), 45.5 years (30.3-56.0 years), 42 men, 44 women) and 47 LBP (median age 51.0 year (39.5-57.5) years, 21 men, 26 women) were enrolled. Median EIM 100kHz phase was lower in the LBP patients (9.3°(IQR 8.4°-10.6°) versus 11.4°(IQR 9.4°-13.0°), p = 0.0007). Significantly increased normalized side-to-side differences were present for all three EIM variables (e.g., median 100 kHz phase 0.15 (IQR 0.07-0.31 in LBP patients versus 0.09 (IQR 0.04-0.17) in healthy individuals). A significant correlation between 100 kHz EIM phase and reactance was found with age (Rspearman=-0.46, P=0.0002 and Rspearman=-0.440, P=0.0003) but not for resistance. This study provides early evidence supporting that EIM has the potential to serve as a useful tool for evaluating the condition of LPMs.

Contralateral Oblique View Is Superior to the Lateral View for Lumbar Epidural Access.

OBJECTIVE: The purpose of this study was to perform a comparative analysis of the contralateral oblique (CLO) view and the lateral view for lumbar interlaminar epidural access. DESIGN: After the epidural space was accessed, fluoroscopic images at eight different angles (antero-posterior view, multiple CLO, and lateral view) were prospectively obtained. Visualization and location of needle tip relative to bony landmarks were analyzed. The epidural location of the needle was subsequently confirmed by contrast injection and analysis in multiple views. RESULTS: Visualization of the needle tip and the relevant radiologic landmarks was superior in the CLO view. The needle tip location in the epidural space was most consistent at a CLO angle of 45°. CONCLUSION: This study shows that the CLO view for lumbar interlaminar epidural access offers clear advantages over the lateral view on many clinically important grounds: the needle tip visualization is better, the important radiological landmarks are better visualized, and the needle tip when placed in the epidural space presents a more precise relationship to these landmarks. All of these differences were highly significant. Thus, when using this view, the needle may be directly placed in very close vicinity to the epidural space and true loss of resistance expected soon thereafter. In addition, this view provides the ability to plot the cranio-caudad needle trajectory. The combination of these factors is likely to improve the ease and efficiency of epidural access. The crisp visualization of the final moments of epidural access could also translate to improved safety and accuracy. In light of this, it is suggested that a CLO view at 45° be considered the preferred view for gauging needle depth during interlaminar lumbar epidural access.

Exploration of sensory impairments associated with C6 and C7 radiculopathies.

BACKGROUND CONTEXT: Cervical radiculopathy is a common disorder caused by compression of the cervical nerve roots and is characterized by arm pain and altered sensory-motor function. Incongruity in the locations of C6 and C7 dermatomes in competing versions of historical dermatome maps has plagued interpretation of impaired sensation associated with C6 and C7 radiculopathies. Magnetic resonance imaging (MRI) allows accurate identification of the C6 or C7 nerve root compression and therefore makes it possible to explore sensory findings that are associated with compression of specific nerve root. PURPOSE: This study compared the locations of impaired sensation in subjects with cervical radiculopathy from MRI-confirmed C6 and C7 nerve root compression. STUDY DESIGN: Case series was used for this study. PATIENT SAMPLE: A total of 122 subjects with symptoms suggestive of cervical radiculopathy were recruited by 11 spine specialist from 5 practice locations. Of these, 30 subjects had MRI-confirmed C6 and 40 subjects C7 radiculopathy. OUTCOME MEASURES: Standardized pinprick sensory examination of the forearm and hand of every subject was performed, and the locations of sensory impairments were recorded. METHODS: Sensory examination was performed before reviewing MRI results or performing motor or reflex examination. Areas of impaired sensation were recorded on drawings of the palmar and dorsal forearm and hand, and translated using a grid into 36 specific areas for analysis. Chi-square was used to compare frequencies of findings for each grid area for C6 and C7 radiculopathies. Power analysis suggested that a minimum of 27 subjects in each group were needed to detect a 30 percentage point difference in frequency of sensory impairments. Significance was set at ≤.05. RESULTS: Approximately 80% of subjects had impaired sensation in at least 1 grid area, most often in the distal forearm and hand, and many had findings in multiple areas. There was nearly complete overlap for locations of impaired sensation for C6 and C7 radiculopathy, and the frequencies of impaired sensation differed only in the dorsal aspect of the distal radial forearm where it was twice as common in C6 radiculopathy (p=.02). CONCLUSIONS: The location of sensory impairments associated with symptomatic C6 and C7 nerve root compression overlap to the extent that caution should be exercised when predicting compression of either the C6 or C7 nerve roots based on locations of impaired sensation. Impaired sensation in the radial aspect of the distal forearm is more common in C6 radiculopathies.

Contralateral oblique view is superior to lateral view for interlaminar cervical and cervicothoracic epidural access.

OBJECTIVE: The purpose of this study was to compare the reliability of the lateral fluoroscopic view and several contralateral oblique (CLO) views at different angles in visualizing and accurately predicting the position of the needle tip at the point of access in the posterior cervical and cervicothoracic epidural space. DESIGN: After the epidural space was accessed but before confirmation with contrast fluoroscopy, we prospectively obtained fluoroscopic images at eight different angles. Subsequent contrast injection confirmed epidural spread. Needle tip visualization and location of needle relative to bony landmarks were analyzed. RESULTS: The needle tip was clearly visualized in all CLO projections in all 24 subjects. CLO view at 50 degrees and at obliquity measured on magnetic resonance imaging (MRI) images provided the most consistent needle tip location. In these views, the epidural space was accessed at or just beyond the ventral laminar margin at the ventral interlaminar line or within the proximal half of the predefined CLO area in all patients. The needle tip was poorly visualized in the lateral view and the location of the needle tip was less well defined and independent of the needle location in the anteroposterior (AP) view. CONCLUSIONS: This study provides evidence that during cervical and cervicothoracic epidural access, the CLO view at 50 degrees and at MRI-measured obliquity is superior to the lateral view for the purpose of needle tip visualization and in providing a consistent landmark for accessing the epidural space. This article also introduces the concept of zones to describe needle position in the cervical and cervicothoracic spine in AP, lateral, and oblique views.

Computed tomography-based muscle attenuation and electrical impedance myography as indicators of trunk muscle strength independent of muscle size in older adults.

OBJECTIVE: The aim of this study was to examine the associations of computed tomography-based x-ray attenuation and paraspinal electrical impedance myography measures of trunk muscles with absolute and relative (normalized by body weight) trunk extension strength, independent of muscle cross-sectional area. DESIGN: This is a cross-sectional study of mobility-limited community-dwelling older adults (34 women, 15 men; mean [SD] age, 78.2 [7.2] yrs) recruited from within an existing prospective research cohort. Trunk extension strength, computed tomography-based trunk muscle cross-sectional area and attenuation at L4 level, and paraspinal electrical impedance myography measures were collected. RESULTS: Attenuation was positively correlated with absolute and relative strength for multiple muscle groups (r = 0.32-0.61, P < 0.05). Paraspinal electrical impedance myography phase was positively correlated with paraspinal attenuation (r = 0.30, P = 0.039) and with relative strength (r = 0.30, P = 0.042). In multivariable linear regressions adjusting for sex and cross-sectional area, attenuations of the anterior abdominal muscles (semipartial r = 0.11, P = 0.013) and combined muscles (semipartial r = 0.07, P = 0.046) were associated with relative strength. CONCLUSIONS: Although attenuation was associated with relative strength, small effect sizes indicate limited usefulness as clinical measures of muscle strength independent of muscle size. However, there remains a need for additional studies in larger and more diverse groups of subjects.

Electrical impedance myography in the diagnosis of radiculopathy.

INTRODUCTION: We sought to determine whether electrical impedance myography (EIM) could serve as a diagnostic procedure for evaluation of radiculopathy. METHODS: Twenty-seven patients with clinically and radiologically diagnosed cervical or lumbosacral radiculopathy who met a "gold standard" definition underwent EIM and standard needle electromyography (EMG) of multiple upper or lower extremity muscles. RESULTS: EIM reactance values revealed consistent reductions in the radiculopathy-affected myotomal muscles as compared with those on the unaffected side; the degree of asymmetry was associated strongly with the degree of EMG abnormality (P < 0.001). EIM had a sensitivity of 64.5% and a specificity of 77.0%; in comparison, EMG had a sensitivity of 79.7% but a specificity of 69.7%. CONCLUSIONS: These findings support the potential for EIM to serve as a new non-invasive tool to assist in diagnosis of radiculopathy; however, further refinement of the technique is needed for this specific application.

Spinal cord stimulation for radicular pain following retained bullet in the spinal canal.

We are reporting on the implantation of a spinal cord stimulator to treat intractable radicular pain following a retained bullet fragment in the spinal canal. Such retained fragments are associated with risks including pain, neurological deficit, infection, toxic effects, and migration. Our patient was a young man with radicular pain and history of a gunshot entering the abdomen. Computed tomography of the spine had revealed a nearly complete bullet in the right paracentral canal at L4, partially extending into the lateral recess. He presented 17 months after his injury with gradually worsening pain and parasthesias radiating from the back to the whole right leg and foot. There was no weakness. As the patient had failed conservative therapy, procedural options were considered. In this case, the potential benefits of epidural steroid injection by any approach might not have outweighed risks of infection, related to foreign body and local steroid, or possible migration due to mechanical forces during injection. As he may well need repeated epidural steroid injections to manage his pain, this increases his risk for infection. A percutaneous trial spinal cord stimulation lead was placed, with epidural entry well away from the bullet. After good results, a permanent system was implanted. There was no evidence of infection or migration, and excellent pain relief was achieved. Bullets and other foreign bodies retained in the spinal canal can cause progressive neurologic symptoms through reactive tissue formation and compression. Spinal cord stimulation can relieve radicular pain while avoiding risks associated with altering the location of the offending foreign body.

Iatrogenic hypercortisolism complicating triamcinolone acetonide injections in patients with HIV on ritonavir-boosted protease inhibitors.

Epidural corticosteroid injection is a commonly used approach for managing back pain of several etiologies. The risk of clinical complications from systemic absorption is felt to be rare. Ritonavir is a protease inhibitor whose potent cytochrome P450 3A4 inhibition is exploited for pharmacologic boosting in human immunodeficiency virus (HIV) infection. It has been associated with systemic hypercortisolism when used in combination with nasal and inhaled corticosteroids. This is a case series describing 2 patients with HIV on ritonavir-containing regimens who developed iatrogenic hypercortisolism following epidural injection of triamcinolone acetonide. The 2 patients developed cushingoid symptoms, with detectable serum triamcinolone acetonide levels weeks after their epidural injections. Their symptoms took several weeks to resolve, in one case necessitating a change to an HIV regimen that did not contain ritonavir. Iatrogenic hypercortisolism is a rarely reported, but potentially devastating complication of injectable corticosteroids. Individuals receiving ritonavir-based therapy appear to be at increased risk for this process due to pharmacologic boosting of the corticosteroid. The preponderance of reported cases of iatrogenic hypercortisolism following injectable corticosteroids has involved triamcinolone acetonide, which may be due to the relatively rapid absorption characteristics and high serum levels of this compound compared with other preparations. For individuals on ritonavir-containing HIV therapy, we recommend close coordination with the involved HIV clinicians prior to use of injectable corticosteroids, and avoidance of injections with triamcinolone acetonide whenever possible. Choosing an alternative corticosteroid preparation to triamcinolone acetonide may reduce the risk of systemic absorption, though more research is needed to confirm this hypothesis.

Utilizing a handheld electrode array for localized muscle impedance measurements.

INTRODUCTION: Electrical impedance myography (EIM) is a noninvasive technique used for assessment of muscle health in which a high-frequency, low-amplitude electric current is applied to the skin overlying a muscle, and the resulting surface voltage is measured. We have previously used adhesive electrodes, application of which is inconvenient. We present data using a handheld electrode array (HEA) that we devised to expedite the EIM procedure in a clinical setting. METHODS: Thirty-four healthy volunteers and 24 radiculopathy subjects underwent EIM testing using the HEA and adhesive electrodes. RESULTS: The HEA was shown to have good test-retest reproducibility, with intraclass correlation coefficients as high as 0.99. HEA data correlated strongly with data from adhesive electrodes, ρ = 0.85 in healthy volunteers (P < 0.001) and ρ = 0.75 in radiculopathy subjects (P < 0.001). CONCLUSIONS: These data support the potential use of a handheld array for performing rapid localized surface impedance measurements.

Musculocutaneous nerve injury after simulated freefall in a vertical wind-tunnel: a case report.

We report a case of a skydiver with isolated musculocutaneous nerve injury, which occurred after prolonged positioning of the arm during simulated freefall in a vertical wind-tunnel. Musculocutaneous nerve injury is rare, and the mechanism of isolated injury to this nerve is not entirely understood. Isolated peripheral nerve injuries such as this easily mimic other injuries and can be difficult to diagnose. The skydiver complained of right arm weakness and numbness that began after training in a vertical wind-tunnel. Exam revealed weakness in right elbow flexion and forearm supination, and diminished sensation in the right lateral forearm. Electrodiagnostic testing revealed a decreased amplitude in the right lateral antebrachial cutaneous nerve sensory nerve action potential, and fibrillations and positive sharp waves in the biceps and brachialis muscles. By 5 months, the subject reported complete sensory and motor recovery. Physical and electrodiagnostic findings corresponded to the distribution of the musculocutaneous nerve. The mechanism of injury was likely the prolonged abducted, extended, and externally rotated position of the shoulder during simulated freefall. Although isolated nerve injuries are uncommon, unusual activities and physiologic demands of athletes can result in such injuries. It is important to be aware of peripheral nerve injuries to facilitate proper diagnosis and management.