Objective : The purpose of this study was to compare clinical and radiological outcomes of percutaneous endoscopic lumbar discectomy (PELD) and open lumbar microdiscectomy (OLM) for recurrent disc herniation. Methods : Fifty-four patients, who underwent surgery, either PELD (25 patients) or repeated OLM (29 patients), due to recurrent disc herniation at L4-5 level, were divided into two groups according to the surgical methods. Excluded were patients with sequestrated disc, calcified disc, severe neurological deficit, or instability. Clinical outcomes were assessed using Visual Analogue Scale (VAS) score and Oswestry Disability Index (ODI). Radiological variables were assessed using plain radiography and/or magnetic resonance imaging. Results : Mean operating time and hospital stay were significantly shorter in PELD group (45.8 minutes and 0.9 day, respectively) than OLM group (73.8 minutes and 3.8 days, respectively) (p < 0.001). Complications occurred in 4% in PELD group and 10.3% in OLM group in the perioperative period. At a mean follow-up duration of 34.2 months, the mean improvements of back pain, leg pain, and functional improvement were 4.0, 5.5, and 40.9% for PELD group and 2.3, 5.1, and 45.0% for OLM group, respectively. Second recurrence occurred in 4% after PELD and 10.3% after OLM. Disc height did not change after PELD, but significantly decreased after OLM (p = 0.0001). Neither sagittal rotation angle nor volume of multifidus muscle changed significantly in both groups. Conclusion : Both PELD and repeated OLM showed favorable outcomes for recurrent disc herniation, but PELD had advantages in terms of shorter operating time, hospital stay, and disc height preservation.

Percutaneous endoscopic lumbar discectomy (PELD) is one of the surgical options for soft lumbar disk herniation, but the learning curve is perceived to be steep. The first 51 PELD cases performed for singlelevel intracanalicular lumbar disk herniation causing radiculopathy by the same surgeon were prospectively studied. The patients were divided into 3 groups of 17 patients, and the PELD learning curve was assessed by evaluating operating time, failure rate, complication rate, and 1-year reherniation rate. One-year clinical success rate was assessed by telephone interviews. The herniated disk was successfully removed by PELD in 47 patients. Four patients required subsequent open discectomy due to PELD failure. There were 2 minor complications. One year after surgery, clinical success was achieved in 42 of the 47 patients in whom PELD was initially successful, and reherniation developed in 5 patients. A significant reduction in operating time was observed after 17 patients had been treated (p ＝ 0.0004). No significant differences were observed in terms of either failure rate or complication rate between the 3 groups. No significant differences were observed in terms of either the clinical success rate or the reherniation rate at 1 year after surgery. The PELD learning curve seems to be stable and acceptable with proper pre-PELD training.

201by lumbar disc herniation. For this purpose, we assessed the CSAs of these muscles using magnetic resonance imaging (MRI). Based on the results, we suggest possible remedies to hasten the recovery after lumbar disc surgery. MATERIALS AND METHODS Patient populationWe retrospectively analyzed data obtained from 76 consecutive patients who underwent conventional open microdiscectomy for severe leg pain caused by lumbar disc herniation in 2005, of which 39 patients (51.3%) had a symptom duration of 1 month or less (group A), and 37 (48.7%) had a symptom duration of 3 months or more (group B). The inclusion criteria of group A were as follows : 1) single-level lumbar disc herniation at L4-5 level on computed tomography and/or MRI; 2) severe leg pain that was consistent with the radiologic findings; 3) leg pain that did not respond to conservative treatment; and 4) interval from symptom onset to surgery of 1 month or less. Patients with chronic low back pain, motor weakness, and/or previous history of lumbosacral spinal surgery were excluded. Group A comprised 27 men and 12 women with a mean age of 42.2±7.9 years (range, 25-58 years). The mean symptom duration INTRODUCTIONSciatica is characterized by radiating pain in an area of the leg typically served by one nerve root in the lumbar or sacral spine. The most common cause of sciatica is lumbar disc herniation. The clinical course of sciatica is considered favorable, with resolution of leg pain via conservative treatment in a majority of the patients 15) . However, atrophy of the ipsilateral multifidus or psoas muscles has been reported in cases of sciatica caused by lumbar disc herniation 2,3,10) . Dangaria and Naesh 3) noted a significant reduction in the cross sectional area (CSA) of the ipsilateral psoas in patients with unilateral lumbar disc herniation. Hyun et al. 10) reported a significant decrease in the CSA of the ipsilateral multifidus in patients with unilateral lumbosacral radiculopathy.The aim of the current study was to investigate whether asymmetry of the multifidus and psoas muscle occurred and whether it was related to the duration of the unilateral sciatica caused Department of Neurosurgery, Wooridul Spine Hospital, Seoul, KoreaObjective : To quantitatively evaluate the asymmetry of the multifidus and psoas muscles in unilateral sciatica caused by lumbar disc herniation using magnetic resonance imaging (MRI). Methods : Seventy-six patients who underwent open microdiscectomy for unilateral L5 radiculopathy caused by disc herniation at the L4-5 level were enrolled, of which 39 patients (51.3%) had a symptom duration of 1 month or less (group A), and 37 (48.7%) had a symptom duration of 3 months or more (group B). The cross-sectional areas (CSAs) of the multifidus and psoas muscles were measured at the mid-portion of the L4-5 disc level on axial MRI, and compared between the diseased and normal sides in each group. Results : The mean symptom duration was 0.6±0.4 months and 5.4±2.7 months for groups A and B, respectively (p<0.001). There were no dif...

Good results were achieved with surgery for Types IVa and IVb PMAVF located at the level of the conus medullaris. For Type IVc PMAVF, a fistula located on the ventral side of the spinal cord or above the conus medullaris, endovascular treatment might be considered. Because of rapidly evolving endovascular techniques, however, further studies are warranted.

Object The purpose of this study was to analyze the surgical outcomes in cases involving elderly patients who underwent single-level instrumented mini-open transforaminal lumbar interbody fusion (TLIF). Methods The authors performed a retrospective review of 27 consecutive cases involving elderly patients (≥ 65 years of age) who underwent single-level instrumented mini-open TLIF and were followed up for at least 3 years. Degenerative spondylolisthesis was diagnosed in 16 patients, stenosis with instability in 8, and lytic spondylolisthesis in 3. All cases were Grade I or II based on the American Society of Anesthesiologists' classification system. Clinical outcomes were assessed using a visual analog scale, the Oswestry Disability Index, and patients' subjective satisfaction. Sagittal balance, bone union, and adjacent segment degeneration (ASD) were assessed using plain radiography and 3D CT. Results The mean age of patients at the time of surgery was 69.3 years (range 65–80 years). Minor complications occurred in 2 patients (7.4%) in the perioperative period. At a mean follow-up duration of 38.6 months (range 36–42 months), clinical success was achieved in 88.9% of cases. The mean segmental lordosis and sacral tilt significantly increased after surgery (from 11.9 and 33.5° to 13.9 and 37.2°, p = 0.024 and p = 0.001, respectively). Solid fusion was achieved in 77.8% of the patients. Adjacent segment deterioration was found in 44.4% of the patients. No patients underwent revision surgery due to nonunion or ASD. The development of ASD was significantly related to postoperative sacral tilt (p = 0.006). Conclusions Single-level instrumented mini-open TLIF yielded good clinical and radiological outcomes with a low complication rate in elderly patients.