Timothy P. Maus

Image-guided ablation of painful metastatic bone tumors: a new and effective approach to a difficult problem.

Painful skeletal metastases are a common problem in cancer patients. Although external beam radiation therapy is the current standard of care for cancer patients who present with localized bone pain, 20–30% of patients treated with this modality do not experience pain relief, and few further options exist for these patients. For many patients with painful metastatic skeletal disease, analgesics remain the only alternative treatment option. Recently, image-guided percutaneous methods of tumor destruction have proven effective for treatment of this difficult problem. This review describes the application, limitations, and effectiveness of percutaneous ablative methods including ethanol, methyl methacrylate, laser-induced interstitial thermotherapy (LITT), cryoablation, and percutaneous radiofrequency ablation (RFA) for palliation of painful skeletal metastases.

Popliteal Artery Aneurysms: The Risk of Nonoperative Management

To evaluate the risk of nonoperative management of popliteal artery aneurysms (PAAs), a retrospective cohort study of 106 consecutive patients (103 males and 3 females) with PAAs seen between January 1, 1980, and December 31, 1985, was performed. The mean age was 70.5 years (range 50 to 90 years). The 106 patients with 161 PAAs were followed for a mean of 6.7 years (range 3 days to 12.1 years). Follow-up was complete in 91.5% (97/106) of the patients. PAA was confirmed by ultrasonography in 124 limbs (77%), arteriography only in 7 (4.3%), and physical examination only in 32 (19.9%). Fifteen limbs presented with acute symptoms, 52 with chronic symptoms, and 94 were asymptomatic. Five of the 15 limbs with acute symptoms (33%) underwent amputation (4 primary, 1 secondary). PAAs in 23 of the 52 limbs with chronic symptoms were repaired; 2 limbs required amputation (8.7%). Twenty-seven of the 94 asymptomatic limbs were repaired initially; 1 required amputation (3.7%). The remaining 67 asymptomatic limbs were initially managed nonoperatively. Amputation was required in 3 of 67 limbs (4.4%), 1 with acute symptoms and 2 with chronic symptoms, all of which had undergone attempted repair. Symptoms (3 acute, 9 chronic) eventually developed in 12 (17.9%). At least one of three risk factors (size >2 cm, thrombus, and poor runoff) was initially present in 11 of 12 limbs (91.7%) compared with 9 of 24 control limbs (37.5%) that remained asymptomatic (p<0.05). Amputation rates in symptomatic patients with PAAs continues to be high. In patients with asymptomatic PAAs, aneurysm size >2 cm, thrombus, or poor runoff predicted the development of symptoms. PAA patients with any of these factors should undergo elective repair, even asymptomatic patients who have a reasonable chance for long-term survival.

Anatomic relationship of the internal carotid artery to the C1 vertebra: A case report of cervical reconstruction for chordoma and pilot study to assess the risk of screw fixation of the atlas.

Study Design. A case of internal carotid artery impingement by the tip of a well-positioned C1–C2 transarticular screw is presented along with a pilot study involving radiologic and anatomic evaluation of human cadaveric specimens. Objective. To raise awareness that the internal carotid artery may be in close proximity to the anterior aspect of the atlas and at risk of injury during placement of C1–C2 transarticular screws or C1 lateral mass screws. Summary of Background Data. To our knowledge, no cases of internal carotid artery injury or impingement have been reported with screw fixation of the atlas. Methods. A case of internal carotid artery impingement by a C1–C2 transarticular screw is presented. The C1–C2 rotation appeared to place the internal carotid artery in the path of the screw, prompting a pilot study. Three fresh-frozen human cadaveric head and neck specimens were fixed in different degrees of rotation. Thin-section computed tomography of the specimens was obtained in the plane of the atlas. The frozen specimens were sectioned in the same plane as the computed tomography images. Measurements were taken to assess the location of the internal carotid artery relative to the anterior aspect of the atlas. Results. Cervical rotation does not have a predictable effect on the location of the internal carotid artery. Medial angulation of a screw placed in the lateral mass of C1 appears to increase the margin of safety for the internal carotid artery. The internal carotid artery varies in location and may be within 1 mm of the ideal exit point of a bicortical transarticular screw or a C1 lateral mass screw. Conclusions. The internal carotid artery is at risk during bicortical screw fixation of the atlas. We recommend a contrast-enhanced computed tomography to assess the location of the internal carotid artery before screw fixation of the atlas.

Intraforaminal Location of the Great Anterior Radiculomedullary Artery (Artery of Adamkiewicz): A Retrospective Review

PURPOSE The purpose of this study was to better characterize the intraforaminal location of the great anterior radiculomedullary artery (artery of Adamkiewicz [AKA]) within the neural foramen that would allow safer targeting of thoracic and lumbar transforaminal epidural steroid injections. MATERIAL AND METHODS A retrospective review of conventional thoracic and lumbar spinal angiograms performed at the Mayo Clinic from 1998-2008 was conducted. Two hundred forty-eight patients were identified and their spinal angiograms reviewed. The cephalo-caudal location of the AKA within the foramen at the mid-pedicular plane was documented along with the side and level of the AKA. RESULTS From the 248 patients, 113 radiculomedullary arteries could be clearly evaluated within a neural foramen. The AKA was located in the superior one-half of the foramen in 97% (110). Eighty-eight percent (100) were located in the upper third; 9% (10) were located in the middle third; and 2% (2) were located in the lower third. The AKA was never seen in the inferior one-fifth of the foramen. Eighty-eight percent (100) of the radiculomedullary arteries were located on the left while 17% (20) were located on the right. The radiculomedullary arteries were identified from T2-L3. 92% (110) were located between T8 and L1. 28% (34) were located at T10, the highest incidence. CONCLUSIONS The AKA was overwhelmingly located in the superior aspect of the neural foramen. Contrary to traditional teaching, the safest needle placement for an epidural steroid injection, particularly at L3 and above, may not be in the superior aspect of the foramen, but rather in an inferior and slightly posterior position within the foramen and relative to the nerve.

The Noninferiority of the Nonparticulate Steroid Dexamethasone vs the Particulate Steroids Betamethasone and Triamcinolone in Lumbar Transforaminal Epidural Steroid Injections

OBJECTIVE To assess whether a nonparticulate steroid (dexamethasone, 10 mg) is less clinically effective than the particulate steroids (triamcinolone, 80 mg; betamethasone, 12 mg) in lumbar transforaminal epidural steroid injections (TFESIs) in subjects with radicular pain with or without radiculopathy. DESIGN Retrospective observational study with noninferiority analysis of dexamethasone relative to particulate steroids. SETTING Single academic radiology pain management practice. SUBJECTS Three thousand six hundred forty-five lumbar TFESIs at the L4-5, L5-S1, or S1 neural foramina, performed on 2,634 subjects. METHODS/OUTCOME MEASURES Subjects were assessed with a pain numerical rating scale (NRS, 0-10) and Roland-Morris disability questionnaire (R-M) prior to TFESI, and at 2 weeks and 2 months follow-up. For categorical outcomes, successful pain relief was defined as either ≥50% reduction in NRS or pain 0/10; functional success was defined as ≥40% reduction in R-M score. Noninferiority analysis was performed with δ = -10% as the limit of noninferiority. Continuous outcomes (mean NRS, R-M scores) were analyzed for noninferiority with difference bounds of 0.3 for NRS scores and 1.0 for R-M scores. RESULTS With categorical outcomes, dexamethasone was demonstrated to be noninferior to the particulate steroids in pain relief and functional improvement at 2 months. Using continuous outcomes, dexamethasone was demonstrated to be superior to the particulate steroids in both pain relief and functional improvement at 2 months. CONCLUSION This retrospective observational study reveals no evidence that dexamethasone is less effective than particulate steroids in lumbar TFESIs performed for radicular pain with or without radiculopathy.

Imaging the Back Pain Patient

Imaging is an integral part of the clinical examination of the patient with back pain; it is, however, often used excessively and without consideration of the underlying literature. The primary role of imaging is the identification of systemic disease as a cause of the back or limb pain; magnetic resonance imaging (MRI) excels at this. Systemic disease as a cause of back or limb pain is, however, rare. Most back and radiating limb pain is of benign nature, owing to degenerative phenomena. There is no role for imaging in the initial evaluation of the patient with back pain in the absence of signs or symptoms of systemic disease. When conservative care fails, imaging may be undertaken with due consideration of its risks: labeling the patient as suffering from a degenerative disease, cost, radiation exposure, and provoking unwarranted minimally invasive or surgical intervention. Imaging can well depict disc degeneration and disc herniation. Imaging can suggest the presence of discogenic pain, but the lack of a pathoanatomic gold standard obviates any definitive conclusions. The imaging natural history of disc herniation is resolution. There is very poor correlation between imaging findings of disc herniation and the clinical presentation or course. Psychosocial factors predict functional disability due to disc herniation better than imaging. Imaging with MRI, computed tomography (CT), or CT myelography can readily identify central canal, lateral recess, or foraminal compromise. Only when an imaging finding is concordant with the patients pain pattern or neurologic deficit can causation be considered. The zygapophysial (facet) and sacroiliac joint are thought to be responsible for axial back pain, although with less frequency than the disc. Imaging findings of the structural changes of osteoarthritis do not correlate with pain production. Physiologic imaging, either with single-photon emission CT bone scan, heavily T2-weighted MRI sequences (short-tau inversion recovery), or gadolinium enhancement, can detect inflammation and are more predictive of an axial pain generator.

Relationship of the internal carotid artery to the anterior aspect of the C1 vertebra: Implications for C1-C2 transarticular and C1 lateral mass fixation

Study Design. Anatomic study of the internal carotid artery (ICA) location with respect to C1 based on computed tomography (CT) scans with contrast medium. Objective. To measure the location of the ICA relative to the anterior aspect of C1 to assess the risk of placing C1–C2 transarticular or C1 lateral mass screws. Summary of Background Data. Vertebral artery injury is a known risk from placement of screws in C1. A previous case report revealed an ideally placed C1–C2 transarticular screw abutting and narrowing the ICA. The risk of ICA injury from C1 screws is unknown. Methods. Fifty random head and neck CT scans with contrast medium were retrospectively analyzed. Measurements were taken bilaterally including the closest distance from the ICA lumen to C1 and the distance from the medial edge of the ICA to a line drawn along the medial border of the foramen transversarium. The risk of inserting bicortical C1–C2 transarticular and C1 lateral mass screws was estimated based on these measurements. Results. The mean distance from the ICA to C1 was 2.88 mm on the left and 2.89 mm on the right. The ICA lumen was medial to the foramen transversarium in 42 (84%) of 50 cases (mean: 2.78 mm on the left and 3.00 mm on the right). The proximity of the ICA to C1 posed moderate risk in 46% of cases and high risk in 12% (on at least one side). Conclusion. Because of the risk of ICA injury from a drill bit or the tip of a bicortical screw, we recommend preoperative CT scan with contrast medium in all cases in which a screw is to be placed into C1. If the ICA is in close proximity to the anterior border of C1, unicortical fixation or a different fusion technique should be considered.

Clinical effectiveness of single lumbar transforaminal epidural steroid injections

OBJECTIVES To assess the clinical effectiveness of single lumbar transforaminal epidural steroid injections (TFESIs) in subjects with radicular pain with or without radiculopathy. DESIGN Retrospective observational series. SETTING Single academic radiology pain management practice. SUBJECTS Two thousand twenty-four subjects undergoing single lumbar TFESIs at the L4-5, L5-S1, or S1 neural foramina. METHODS / OUTCOME MEASURES Subjects were assessed with a pain numerical rating scale (NRS, 0-10) and Roland-Morris disability questionnaire (R-M, 23-point Deyo modification) prior to TFESI and at 2 weeks and 2 months follow-up. Successful pain relief (responders) was defined as either ≥50% reduction in NRS or pain 0/10; functional success was defined as ≥40% reduction in R-M score. RESULTS There were statistically significant (P < 0.0001) reductions in mean NRS and R-M scores at 2 weeks and 2 months postinjection. For NRS, 40.9% were responders at 2 weeks and 45.6% at 2 months. For R-M, 31.9% were responders at 2 weeks and 41.3% at 2 months. The proportion of responders for NRS and R-M was higher when there was <3 months of pain (odds ratio 2-month NRS = 2.42 [95% confidence interval: 1.82, 3.24], odds ratio 2-month R-M = 2.61 [1.96, 3.48]). For subjects with <3 months of pain, the proportion of responders was 62.4% (56.5, 68.3%) for NRS and 59.3% (53.3, 65.3%) for R-M scores. CONCLUSIONS This retrospective observational study suggests TFESIs are clinically effective in the treatment of lumbar radicular pain. Subjects with a shorter duration of pain are more likely to achieve a successful outcome.

Lumbar spine stabilization with a thoracolumbosacral orthosis: evaluation with video fluoroscopy.

Study Design. L3–L5 vertebral body motion was tracked fluoroscopically as individuals performed flexion–extension movements wearing different thoracolumbosacral orthoses (TLSOs). Objective. To assess the effect of custom fitted TLSOs on lumbar vertebral body motion. Summary of Background Data. Several methods have been used to evaluate dynamic vertebral motion in vivo. Controversy remains regarding the utility of a TLSO in decreasing intervertebral motion in the lumbar spine. Methods. Dynamic motion of the vertebral bodies was assessed fluoroscopically under four conditions: without a brace, with a custom fitted TLSO, with the TLSO and thigh extender at 0° or 15°. Intervertebral motion, i.e., the rotation of one vertebral body with respect to the adjacent body in the sagittal plane, throughout the flexion–extension cycle was used to assess the effect of each condition. Results. The TSLO reduced both the total L3–L5 range of motion and the intervertebral motion at each individual level. Total rotation at L3 with respect to horizontal was reduced from 70° without a brace to 50° with a TLSO. Use of the thigh extender provided an additional reduction to 10°. There was no difference between the 0° and 15° settings. Intervertebral motion was reduced by 40% at both L3–L4 and L4–L5 when comparing no brace to TLSO and an additional 15% when a thigh extender was added. Conclusions. A custom molded TLSO reduces both total L3–L5 motion and intervertebral motion in the lower lumbar spine. These effects are enhanced if a thigh extender is used.

Safety and Efficacy of CT-Guided Transforaminal Cervical Epidural Steroid Injections Using a Posterior Approach

BACKGROUND AND PURPOSE: Image-guided cervical transforaminal epidural injections play an important role in the management of cervical radicular pain syndromes. The safety and efficacy of these injections via an anterolateral approach has been well-studied. The goal of this retrospective review was to determine the safety and efficacy of CT-guided transforaminal epidural injections by using a posterior approach. MATERIALS AND METHODS: Retrospective review of patient records was used to define VNPS and RMDI of patients undergoing CT-guided transforaminal cervical epidural injections between 2006 and 2010. Pain scores were recorded preprocedure, immediately postprocedure, at 2 weeks, and at 2 months. The RMDI was recorded preprocedure, at 2 weeks, and at 2 months. Data analysis of 247 patients was completed. Differences in VNPS scores and the RMDI were then compared on the basis of a CT-guided approach (anterolateral versus posterior). RESULTS: There was no statistical difference in the degree of pain relief and improvement in the RMDI between the CT-guided transforaminal anterolateral approach and the posterior approach at 2 weeks and at 2 months. Both groups demonstrated a statistically significant improvement in pain scores and the RMDI. Approximately 35% of patients in both groups demonstrated >50% pain relief at 2 months. There were no serious complications in either group. CONCLUSIONS: CT-guided transforaminal cervical epidural injections by using a posterior approach are safe and effective.