Morphologic Characteristics and Clinical Significance of Computed Tomography and Magnetic Resonance Imaging Findings of Spinal Epidural Gas.

OBJECTIVE: To evaluate the morphologic characteristics and clinical significance of epidural gas based on computed tomography (CT) and magnetic resonance imaging (MRI) findings and to determine their relationship with radiculopathy. MATERIALS AND METHODS: Between March 2009 and November 2018, 110 epidural gas lesions were identified in 103 patients who underwent both CT and MRI for suspected herniated disc in the authors' institution. Patterns of epidural gas were classified as air pseudocyst, air cyst, air-contained disc herniation, and honeycomb-like air cyst. These gas patterns were compared, and possible correlations between these gas patterns and radiculopathy were evaluated. RESULTS: Overall agreement between CT and MRI findings for evaluation of all lesions and for differentiation of epidural gases was good (kappa [κ] = 0.775). Air pseudocysts demonstrated a moderate correlation (κ = 0.496) and air cysts showed a good correlation (κ = 0.661) with radiculopathy on MRI, whereas air-contained disc herniation and honeycomb-like cysts demonstrated a strong correlation (κ = 0.810 and 0.927, respectively) with radiculopathy on MRI. CONCLUSIONS: This study's results help delineate new classifications of epidural gases. In addition, lumbar epidural gas with disc material (e.g., air-contained disc herniation and honeycomb-like cysts) on MRI was associated with radiculopathy.

A novel preoperative trajectory evaluation method for L5-S1 transforaminal percutaneous endoscopic lumbar discectomy.

BACKGROUND CONTEXT: L5-S1 transforaminal percutaneous endoscopic lumbar discectomy (PELD) is a demanding procedure because of structures such as iliac crest, L5 transverse process, hypertrophic L5-S1 facet joint, and sacral ala. There has been no definite preoperative evaluation method to evaluate the surgical validity of L5-S1 transforaminal PELD. PURPOSE: The authors report a new preoperative trajectory evaluation method for L5-S1 transforaminal PELD using magnetic resonance imaging (MRI) or computed tomography (CT) examinations. STUDY DESIGN/SETTING: This is a technical report study. PATIENT SAMPLE: Patients who were diagnosed L5-S1 soft disc herniation were included in the present study. OUTCOME MEASURES: Success rate of transforaminal PELD according to height of iliac crest was measured. METHODS: Twelve patients who were diagnosed L5-S1 disc herniation were preoperatively evaluated with this new method. A skin marker is attached to patient's back as a tentative skin entry point, which was determined by usual preoperative MRI or CT. A new tilted axial and coronal MRI or CT scan is performed according to axis of L5-S1 transforaminal working channel. The images show good relationship between working channel and iliac crest. RESULTS: Six patients underwent a transforaminal PELD, and the results were successful. The other six patients were considered to be "unsuitable" for transforaminal PELD because of the probable blockade by iliac crest. CONCLUSIONS: The tilted MRI or CT provides precise evaluation for L5-S1 transforaminal PELD trajectory and may achieve good outcome.

Epidural Fluid Collection After Percutaneous Endoscopic Lumbar Discectomy.

OBJECTIVE: The frequency and extent of epidural fluid collection after percutaneous endoscopic lumbar discectomy (PELD) have not been previously described. The purpose of this study was to evaluate the significance of epidural fluid collection after PELD. METHODS: From March 2008 to November 2015, immediate postoperative magnetic resonance imaging (MRI) of 464 consecutive patients, comprising 284 men and 180 women, were obtained after PELD. The mean age of the patients at the time of admission was 43.1 years (range, 18-81 years). We also performed 24-hour follow-up MRIs after PELD in 35 patients to evaluate the morphologic changes on epidural fluid collection and to identify whether the collection was due to saline accumulation or cerebrospinal fluid leak. RESULTS: The level of disc herniation was at L4-5, L5-S1, L3-4, and L2-3 in 245 (52.8%), 173 (37.3%), 37 (8.0%), and 9 (1.9%) patients, respectively. Of 464 patients, 418 (90.1%) had abnormal epidural fluid collection, 404 (87.1%) patients had ventral epidural fluid collection, 393 (84.7%) patients had dorsal epidural fluid collection, and 10 patients had epidural hematoma as per immediate postoperative MRI. According to the 24-hour follow-up MRI findings, 30 patients had epidural fluid collection; the epidural fluid collection in 28 patients (93.3%) resolved with time, and a minimal amount of fluid remained in 2 patients, but the lesion size decreased compared with that on the previous day. CONCLUSIONS: Epidural fluid collection usually occurs after percutaneous endoscopic discectomy, which is mainly due to saline accumulation and typically resolves with time, without treatment or complications.

Comparison between the accuracy of percutaneous and open pedicle screw fixations in lumbosacral fusion.

BACKGROUND CONTEXT: In pedicle screw fixation, accurate insertion is essential to avoid neurological injury or weak stability. The percutaneous pedicle screw system was developed for minimally invasive spine surgery, and its safety has already been reported. However, the accuracy of percutaneous pedicle screw fixation (PPF) has not been compared with that of the open system to date. PURPOSE: To compare the accuracy of PPF with that of open pedicle screw fixation (open PF) and to investigate the risk factors associated with pedicle wall penetration. STUDY DESIGN/SETTING: A retrospective case series. PATIENT SAMPLE: The study group included 237 patients who underwent posterior pedicle screw fixation between January 2008 and October 2010 at a single institute with a total of 1,056 pedicle screw fixations completed. One hundred and twenty-six patients with 558 screws underwent open PF and 111 patients with 498 screws underwent PPF. OUTCOME MEASURES: Postoperative computerized tomography, including sagittal and coronal reformatted images. METHODS: Consecutive surgeries with either conventional open PF or PPF for anterior lumbar interbody fusion or transforaminal lumbar interbody fusion were performed. The open pedicle screw employed was from the WSH system (Winova, Seoul, Korea), and the two percutaneous pedicle screw systems were the Sextant (Medtronics, Minneapolis, MN, USA) and the Viper systems (DePuy Spine, Raynham, MA, USA). Computed tomography images were evaluated to determine pedicle wall penetration after operation. Severity was classified as mild (<3 mm), moderate (3-6 mm), and severe (≥6 mm), and the direction was assessed as medial, lateral, inferior, and superior. RESULTS: Pedicle wall penetration occurred in 75 patients (13.4%) in the open PF group and 71 patients (14.3%) in the PPF group and was not statistically different between the groups (p=.695). Assessment of the severity of the pedicle wall penetration revealed that minor penetration was the most common (open PF group, 9.7%; PPF group, 10.6%), although the distribution of the degree of severity was not statistically different between the groups (p=.863). A relatively higher incidence of lateral penetration was observed in the open PF group (66.7% vs. 43.7%), whereas medial, superior, and inferior penetrations were higher in the PPF group (p=.033). Other parameters such as age, sex, surgical method, and surgeon factors did not influence the penetration rate, but bone mineral densitometry negatively correlated with the penetration. CONCLUSIONS: Pedicle wall penetration during screw fixation was not different between the open PF and PPF groups. The lateral, paraspinal, muscle-splitting approach seems to lessen medial wall penetration, especially in the S1 vertebra. Distribution of the direction of penetration differs between the groups, with lateral wall penetration being more prominent in the open PF group. Careful placement of pedicle screws is necessary for a stronger construct because of the high incidence of penetration.

MRI versus CT for the diagnosis of lumbar spinal stenosis.

OBJECTIVE: The purpose of the study was to compare the effectiveness of CT and MRI in visualizing soft tissues in lumbar spinal stenosis (LSS), and to correlate the images with preoperative symptoms. MATERIALS AND METHODS: A total of 163 patients who had undergone unilateral laminotomy for bilateral decompression to treat LSS at L4-5 were retrospectively analyzed. The narrowed spinal canal area was measured on axial images with CT and MRI, and compared with the acquired dimensions from preoperative Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) scores. RESULTS: The mean compromised spinal canal areas were 75.08 mm(2) on MRI and 63.13 mm(2) on CT, which were significantly different. Mean VAS for back pain was 5.37, and 7.94 for leg pain. Mean ODI was 55.17%. There was no significant correlation noted between clinical parameters and narrowed spinal canal area. CONCLUSION: Spinal canal area was more narrowed on CT than on MRI in axial cuts. This finding can be explained by the superior ability of multidetector CT to discriminate cortical bone from soft tissue such as the ligamentum flavum. Our study highlights the value of CT examination in combination with MRI prior to LSS surgery.

Spinal meningeal melanocytoma in the S-1 nerve root sheath with paraspinal extension mimicking schwannoma.

BACKGROUND: Spinal melanocytomas are variants that can be extradural or intradural and are most often located in the intradural extramedullary compartment of the main thecal sac as in schwannomas. However, origin of this variant from the pure peripheral compartment of rootlets is exceedingly rare. CASE DESCRIPTION: The authors present a case of spinal melanocytoma with confusing pathologic and radiologic features. This patient presented clinically with severe radiating pain on the right lower extremity. Before surgery, clinical and radiologic findings were consistent with a schwannoma. However, on operation, a coal-black pigmented lesion mimicking old blood clot was found inside the right S-1 root sheath, attached to the dura. The mass was completely removed and consequently the patient's symptoms improved. CONCLUSIONS: The spinal melanocytoma should be included as a differential diagnosis before giving a presumptive diagnosis of schwannoma or hemorrhage for the patient with a space-occupying lesion at a peripheral rootlet. Intraoperative gross morphology and histopathologic findings facilitate differential diagnosis.

Radiological findings of spinal schwannomas and meningiomas: focus on discrimination of two disease entities.

This study evaluates the effectiveness of CT and MR imaging in differentiating intradural extramedullary spinal schwannomas and meningiomas in a large group of patients. In addition, the study correlates tumour location, morphologic characteristics and enhancement pattern. From January 2000 to June 2007, we retrospectively reviewed 128 consecutive patients (51 male, 77 female; mean age at admission 53.8 years; range 17-83 years) with spinal intradural extramedullary tumours (92 schwannomas, 36 meningiomas) at our institution. Fifty-one of ninety-two schwannomas (55.4%) showed fluid signal intensity on T2-weighted MR images. Twenty-two of thirty-six meningiomas (61.1%) showed hyperintense signal intensity and thirteen of thirty-six meningiomas (36.1%) showed isointense signal on T2-weighted MR images. Fifty-four schwannomas (58.7%) showed rim enhancement and thirty-three meningiomas (91.7%) showed diffuse enhancement on contrast-enhanced T1-weighted MR imaging. Twenty-one meningiomas (58.3%) showed dural tail sign in contrast-enhanced T1-weighted MR imaging. Twenty-one meningiomas (58.3%) showed calcification on CT images. MR and CT imaging results are therefore useful for the differentiation of schwannomas from meningiomas of the spine.

Effect of intervertebral disk degeneration on spinal stenosis during magnetic resonance imaging with axial loading.

Magnetic resonance (MR) imaging with axial loading can simulate the physiological standing state and disclose spinal stenosis undetected or underestimated in the conventional position. Intervertebral disk degeneration may be an important factor in spinal stenosis. This study investigated whether intervertebral disk degeneration increases spinal stenosis during axial loading. MR imaging with and without axial loading was obtained in 51 patients with neurogenic intermittent claudication and/or sciatica and reviewed retrospectively. The grade of disk degeneration was rated in four disk spaces from L2-3 to L5-S1. The dural sac cross-sectional area (DCSA) was measured on MR images taken in both conventional and axial loading positions, and the change in the DCSA was calculated. The effect of disk degeneration on the DCSA was statistically analyzed. Significant decreases in the DCSA occurred with grade 4 disk degeneration (mean +/- standard deviation, 20.1 +/- 14.1 mm(2)), followed by grade 3 (18.3 +/- 15.1 mm(2)) and grade 2 (8.9 +/- 13.1 mm(2)). DCSA decreased considerably with increased severity of disk degeneration with axial loading, except for grade 5 disk degeneration. More accurate diagnosis of stenosis can be achieved using MR imaging with axial loading, especially if grade 2 to 4 disk degeneration is present.

Transforaminal percutaneous endoscopic lumbar discectomy for upper lumbar disc herniation: clinical outcome, prognostic factors, and technical consideration.

BACKGROUND: Compared with lower lumbar disc herniations, upper lumbar disc herniations at L1-L2 and L2-L3 have specific characteristics that result in different surgical outcomes after conventional open discectomy. There are no published studies on the feasibility of percutaneous endoscopic lumbar discectomy for upper lumbar disc herniation. The purpose of this study was to assess the clinical outcome, prognostic factors and the technical pitfalls of PELD for upper lumbar disc herniation. METHOD: Forty-five patients with a soft disc herniation at L1-L2 or L2-L3 underwent percutaneous endoscopic discectomy. Posterolateral transforaminal endoscopic laser-assisted disc removal was performed under local anesthesia. Clinical outcomes was assessed using the Prolo scale. The prognostic factors associated with outcome were then analyzed. FINDINGS: The mean follow-up was 38.8 months (range, 25-52 months). The outcome of the 45 patients was excellent in 21 (46.7%), good in 14 patients (31.1%), fair in six patients (13.3%), and poor in four patients (8.9%). Four patients with a poor outcome underwent further open surgery. Mean scores on a visual analog scale decreased from 8.38 to 2.36 (P < 0.0001). Age less than 45 years and a lateral disc herniation were independently associated with an excellent outcome (P < 0.05). CONCLUSIONS: Patient selection and an anatomically modified surgical technique promote a more successful outcome after percutaneous endoscopic discectomy for upper lumbar disc herniation.

Midterm results of percutaneous CT-guided aspiration of symptomatic lumbar discal cysts.

OBJECTIVE: Lumbar intervertebral discal cysts are rarely reported. To our knowledge, only 12 cases have been reported in the literature. The symptoms are indistinguishable from those of typical discal herniation. Our aim is to report the imaging characteristics, method of percutaneous CT-guided aspiration, and clinical outcome after management of lumbar intervertebral discal cysts. CONCLUSION: Percutaneous CT-guided aspiration is an effective method for the management of lumbar intervertebral discal cysts.

The balloon dilatation and large profile catheter maintenance method for the management of the bile duct stricture following liver transplantation.

OBJECTIVE: We wanted to evaluate the therapeutic efficacy of the percutaneous balloon dilatation and large profile catheter maintenance method for the management of patients with anastomotic biliary strictures following liver transplant. MATERIALS AND METHODS: From May 1999 to June 2003, 12 patients with symptomatic benign biliary stricture complicated by liver transplantation were treated with the percutaneous balloon dilatation and large profile catheter maintenance method (1-6 months). The patients were eight males and four females, and their ages ranged from 20 to 62 years (mean age: 44 years). Ten patients underwent living donor liver transplantation and two underwent cadaveric liver transplantation. Postoperative biliary strictures occurred from two to 21 months (mean age: 18 months) after liver transplantation. RESULTS: The initial technical success rate was 92%. Patency of the bile duct was preserved for eight to 40 months (mean period: 19 months) in 10 of 12 (84%) patients. When reviewing two patients (17%), secondary balloon dilatations were needed for treating the delayed recurrence of biliary stricture. In one patient, no recurrent stenosis was seen during the further 10 months follow-up after secondary balloon dilatation. Another patient did not response to secondary balloon dilatation, and he was treated by surgery. Eleven of 12 patients (92%) showed good biliary patency for 8-40 months (mean period: 19 months) of follow-up. CONCLUSION: The percutaneous balloon dilatation and large profile catheter maintenance method is an effective therapeutic alternative for the treatment of most biliary strictures that complicate liver transplantation. It has a high success rate and it should be considered before surgery.

The mid-term efficacy and safety of a permanent nitinol IVC filter(TrapEase).

OBJECTIVE: 1) To evaluate the mid-term efficacy and safety of a permanent nitinol inferior vena cava (IVC) filter; 2) to evaluate filter effectiveness, filter stability and caval occlusion. MATERIALS AND METHODS: A prospective evaluation of the TrapEase IVC filter was performed on 42 patients (eight men, 34 women) ranging in age from 22 to 78 years (mean age 66 years). All patients were ill with a high risk of pulmonary embolism (PE). Indications for filter placement were: 1) deep vein thrombosis with recurrent thromboembolism; 2) and/or free-floating thrombus with contraindication to anticoagulation; and 3) complications in achieving adequate anticoagulation. Follow-up evaluations (mean: 15.4 months, range: 2 to 28 months) were performed at 6- and 12-month intervals after the procedure and included clinical histories, chart reviews, plain film, Doppler ultrasounds, and contrasted abdominal CT scans. RESULTS: In follow-up evaluations, the data analysis revealed no cases of symptomatic PE. There were no cases of filter migration, insertion site thrombosis, filter fracture, or vessel wall perforation. During the study, there was one case of filter thrombosis; early symptomatic thrombosis that was successfully treated in the hospital. Of the 42 subjects, eight died. These deaths were not related to the filter device or the implantation procedure, but to the underlying disease. CONCLUSION: This study demonstrates that the TrapEase permanent IVC filter is a safe and an effective device with low complication rates and is best used in patients with thromboembolic disease with a high risk of PE.

Ethanol embolization of arteriovenous malformations: interim results.

PURPOSE: To assess retrospectively the interim results and the complications of ethanol embolization treatment of arteriovenous malformations (AVMs). MATERIALS AND METHODS: Institutional review board approval was obtained for a retrospective review of patient medical and imaging records. Informed consent was not required by the institutional review board. Written consent for the procedure was obtained from all patients after a discussion about the advantages and risks of the procedure. After a general anesthetic was administered, 40 patients (16 male, 24 female; age range, 9-53 years) with inoperable AVMs in the body and extremities underwent staged ethanol embolizations (range, 1-24; median, 3). Pulmonary artery pressure and arterial blood pressure were monitored as ethanol was injected. Ethanol embolizations (50%-100% ethanol mixed with nonionic contrast material) were performed by using transcatheter and/or direct puncture techniques. Ten patients underwent additional coil deployment during ethanol embolization. Clinical follow-up (range, 2-48 months; mean, 14.6 months; median, 12 months) was performed in all patients, and results from imaging follow-up (range, 0-48 months; mean, 8.4 months; median, 6 months) were available from the last treatment session in 28 patients. Therapeutic outcomes were established by evaluating the clinical outcome of symptoms and signs, as well as the degree of devascularization at follow-up angiography. RESULTS: One hundred seventy-five ethanol embolizations were performed in 40 patients. Sixteen (40%) of 40 patients were cured, 11 (28%) had partial remission, seven (18%) had no remission, and one (2%) experienced aggravation. Treatment failed in five patients (12%). Ethanol embolization was considered effective (cure, 16 patients; partial remission, 11 patients) in 27 patients (68%). Eleven patients will need further treatment sessions for residual AVMs. Twenty-one patients (52%) experienced complications. Twenty-seven minor complications (skin and transient peripheral nerve injuries) (27 [15%] of 175 procedures) occurred in 18 (45%) of 40 patients. All minor complications were healed with wound dressing and observation. Five major complications (five [3%] of 175 procedures) occurred in five (12%) of 40 patients, and four patients recovered completely. CONCLUSION: Ethanol embolization has the potential for cure in the management of AVMs of the body and extremities but with acceptable risk of minor and major complications.

Poor sensitivity of sonography in detection of hepatocellular carcinoma in advanced liver cirrhosis: accuracy of pretransplantation sonography in 118 patients.

The objective of this study was to assess the detectability of hepatocellular carcinoma by sonography in advanced cirrhotic patients undergoing liver transplantation. We retrospectively reviewed pretransplantation sonography in 118 consecutive patients with advanced liver cirrhosis. We assessed the detectability of hepatocellular carcinoma in relation to tumor size, location, total liver volume, and degree of sonographic heterogeneity of the liver parenchyma. On pathologic examination, 51 hepatocellular carcinomas were identified in 31 patients. Pretransplantation sonography depicted 14 of 51 (27%) hepatocellular carcinomas. Detectability was significantly affected according to tumor size ( p=0.0099), but there was no significant difference according to tumor location, liver volume, or degree of sonographic heterogeneity of the liver parenchyma. Our study suggests that sonography is not sufficiently sensitive to detect hepatocellular carcinoma in patients with advanced liver cirrhosis. Tumor size is the only factor influencing the detectability of hepatocellular carcinoma.

Selective intra-arterial calcium stimulation with hepatic venous sampling for preoperative localization of insulinomas.

OBJECTIVE: To determine the value of selective intra-arterial calcium stimulation with hepatic venous sampling using serum insulin and C-peptide gradients for the preoperative localization of insulinomas. MATERIALS AND METHODS: Seven consecutive patients (three men and four women aged 15-77 (mean, 42.7) years) with hypoglycemia underwent selective intra-arterial calcium stimulation in conjunction with hepatic venous sampling. Insulin gradients were calculated by an individual blinded to all other preoperative imaging studies and operative findings. In all patients except one, C-peptide gradients were also analyzed. The results were compared with the preoperative findings of ultrasonography, computed tomography, arteriography and endoscopic ultrasonography, as well as with the intraoperative findings of ultrasonography and palpation at surgery. RESULTS: Eight insulinomas (mean diameter, 12.5 mm) were diagnosed after surgery. In six patients, the calcium stimulation test with insulin gradients allowed accurate localization of the pathologic source of insulin secretion. Both C-peptide and insulin gradients substantially increased diagnostic accuracy. In one patient, C-peptide gradients were more helpful than insulin gradients for tumor localization. CONCLUSION: Selective intra-arterial calcium stimulation with hepatic venous sampling is a highly accurate and safe method for the preoperative localization of insulinomas. Additional C-peptide gradients seem to be helpful in assessing tumor location, but further study is needed.