Hirohiko Inanami

Cervical Microendoscopic Interlaminar Decompression through a Midline Approach in Patients with Cervical Myelopathy: A Technical Note

INTRODUCTION Microendoscopic techniques through a unilateral paramedian approach or muscle-preserving techniques using a microscope have been reported as minimally invasive spinal decompression procedures for the cervical spine. In this study, we developed a novel technique, cervical microendoscopic interlaminar decompression (CMID) through a midline approach, for treating cervical compression myelopathy. METHODS A total of 29 consecutive patients with single- or two-level cervical compression myelopathy were reviewed. For the single-level cases (e.g., C5-C6), a midline skin incision, ∼ 2 cm in length, was made at the spinal level to be decompressed (C5-C6) under fluoroscopic guidance. The nuchal ligament was longitudinally cut, and tips of the spinous processes (C5 and C6) were exposed. A 16-mm tubular retractor was inserted between the tips of the C5 and C6 spinous processes. A dome-like laminectomy of C5, partial laminectomy of the upper part of C6, and flavectomy were performed. For the two-level cases (e.g., C4-C5 and C5-C6), the decompression procedure was completed by splitting the spinous process (C5). Pre- and postoperative neurologic status was evaluated using the Japanese Orthopedic Association (JOA) score. Neck and arm pain was also evaluated using a numerical rating scale (NRS). RESULTS Overall, 10 patients underwent single-level decompression, and 19 patients underwent two-level decompression. The average age was 67 years (range: 40-83 years), and the mean follow-up period was 11 months (range: 4-14 months). The average pre- and postoperative JOA scores were 10.2 and 13.5, with a mean recovery rate of 49%. The mean preoperative and postoperative NRS scores were 3.5 and 1.5 for neck pain and 4.6 and 2.9 for arm pain, respectively. One patient showed transient mild weakness of the leg that recovered neurologically within a few weeks. No other postoperative complications were observed. CONCLUSION This procedure revealed good short-term surgical results. This technique has advantages including (1) a symmetrical orientation of the surgical field, (2) an intermuscular incision that minimizes blood loss and muscle trauma, and (3) the ability to safely complete the decompression procedure without retracting the cervical spinal cord compared with the unilateral approach. Although long-term surgical results are required, this technique is not only safe but also minimally invasive as a treatment for cervical compression myelopathy.

Role of 18F-fluoro-D-deoxyglucose PET/CT in diagnosing surgical site infection after spine surgery with instrumentation.

Study Design. Retrospective case series. Objective. To investigate the effectiveness of positron emission tomography/computed tomography (PET/CT) in diagnosing surgical site infection (SSI) after spinal surgery with instrumentation. Summary of Background Data. Several reports have indicated the usefulness of 18F-fluoro-D-deoxyglucose (F-18 FDG) PET in detecting sites of infection including spinal infection sites. However, no report has documented the efficacy of PET/CT in detecting SSI after spinal surgery with instrumentation. Methods. A total of 811 consecutive case patients who underwent minimally invasive posterior lumbar interbody fusion surgery with instrumentation from December 2008 to February 2012 were enrolled. Of these, for all case patients clinically suspected as having SSI by laboratory data and clinical symptoms, PET/CT was performed. Six patients with no apparent sign of SSI served as a control group. Image data were evaluated by 2 nuclear medicine physicians blinded to the clinical and pathological results. The data were quantitatively analyzed by the maximum standardized uptake value as an index of F-18 FDG uptake. Results. Visual assessment by PET/CT revealed that all 8 patients with suspected SSI were positive for infection whereas all 6 controls without apparent infection were negative for infection. There was a statistically significant difference in the maximum standardized uptake values (mean and range) between the SSI and control groups (9.0 and 5.5–14.7 vs. 3.3 and 2.0–4.3, respectively; P = 0.003). All 8 patients underwent surgical debridement with selective implant removal and achieved a good clinical course. Conclusion. PET/CT was effective in diagnosing SSI and identifying infection sites despite the presence of spinal instruments. Although further studies with a larger number of patients are required, PET/CT presents a good candidate for detecting early-phase SSI after instrumented spinal surgery. Level of Evidence: 4

Consideration of proper operative route for interlaminar approach for percutaneous endoscopic lumbar discectomy

BACKGROUND Percutaneous endoscopic lumbar discectomy (PELD) is one of the less invasive treatments of lumbar disc herniation (LDH), and has three different operative approaches. This study focused on the interlaminar approach (ILA) and investigated the appropriate operative route for this approach. METHODS ILA was performed in 41 patients with LDH. The width of the interlaminar space, LDH size, and positional relation between LDH and the corresponding nerve root were radiologically evaluated. Thirty-three LDHs were removed via the shoulder of the corresponding nerve root and eight were removed via the axilla of the corresponding nerve root and dural sac. Pre- and postoperative status were evaluated using the modified Japanese Orthopedic Association (mJOA) and numerical rating scale (NRS) scores. RESULTS The mean age was 41.5 years; there was single-level involvement, mostly at L5/S1 (33 cases). The mean recovery rate of mJOA score was 59.8% and mean pre- and postoperative NRS scores were 5.8 and 0.98, respectively. Relatively severe complications developed in three patients treated by ILA via the shoulder. There was persistent numbness in the corresponding nerve area, transient muscular weakness, and transient bladder and rectal disturbance, may be due to excessive compression of the nerve root and/or dural sac by the endoscopic sheath. CONCLUSIONS ILA can be used to treat LDH revealing an interlaminar space of ≥20 mm. The procedure is minimally invasive and effective; however, appropriate selection of an operative route is important to avoid operative complications. Particularly for large LDH, the operative route via the axilla should be considered.

Microendoscopic Posterior Decompression for the Treatment of Lumbar Lateral Recess Stenosis

Lateral recess stenosis (LRS) is a characteristic type of lumbar spinal canal stenosis, with symptoms of nerve root compression. The most common etiology is hypertrophy of the superior articular process. Conventional laminectomy and medial facetectomy are commonly used to treat LRS. This study investigated microendoscopic posterior decompression for the treatment of LRS. Microendoscopic decompression was performed on 28 patients. Computed tomography and magnetic resonance imaging were used to calculate the lateral recess angle and depth. A 16 mm diameter tubular retractor and endoscopic system were used. Unilateral paramedian approaches were performed in all patients. Even using a unilateral paramedian approach, both sides of the nerve roots were decompressed in patients with bilateral radiculopathy. Preand postoperative status was evaluated using the visual analogue scale (VAS). Patient’s mean age was 62.9 years; there was single-level involvement, mostly at L4-5 (85.7%). Intraoperative findings revealed that the most common cause of nerve root compression was hypertrophy of the superior articular process and ligamentum flavum. VAS score improved in all patients following posterior decompression. Pre- and postoperative mean VAS scores were 6.5 and 1.1, respectively (P value < 0.01). No intra- or postoperative complications were observed during a mean follow-up of 10.5 months.

Diagnosing Discogenic Low Back Pain Associated with Degenerative Disc Disease Using a Medical Interview

Purposes To evaluate the usefulness of our original five questions in a medical interview for diagnosing discogenic low back pain (LBP), and to establish a support tool for diagnosing discogenic LBP. Materials and Methods The degenerative disc disease (DDD) group (n = 42) comprised patients diagnosed with discogenic LBP associated with DDD, on the basis of magnetic resonance imaging findings and response to analgesic discography (discoblock). The control group (n = 30) comprised patients with LBP due to a reason other than DDD. We selected patients from those who had been diagnosed with lumbar spinal stenosis and had undergone decompression surgery without fusion. Of them, those whose postoperative LBP was significantly decreased were included in the control group. We asked patients in both groups whether they experienced LBP after sitting too long, while standing after sitting too long, squirming in a chair after sitting too long, while washing one’s face, and in the standing position with flexion. We analyzed the usefulness of our five questions for diagnosing discogenic LBP, and performed receiver operating characteristic (ROC) curve analysis to develop a diagnostic support tool. Results There were no significant differences in baseline characteristics, except age, between the groups. There were significant differences between the groups for all five questions. In the age-adjusted analyses, the odds ratios of LBP after sitting too long, while standing after sitting too long, squirming in a chair after sitting too long, while washing one’s face, and in standing position with flexion were 10.5, 8.5, 4.0, 10.8, and 11.8, respectively. The integer scores were 11, 9, 4, 11, and 12, respectively, and the sum of the points of the five scores ranged from 0 to 47. Results of the ROC analysis were as follows: cut-off value, 31 points; area under the curve, 0.92302; sensitivity, 100%; and specificity, 71.4%. Conclusions All five questions were useful for diagnosing discogenic LBP. We established the scoring system as a support tool for diagnosing discogenic LBP.

Risk factors for incidental durotomy during posterior open spine surgery for degenerative diseases in adults: A multicenter observational study

Incidental durotomy (ID) is a common intraoperative complication of spine surgery. It can lead to persistent cerebrospinal fluid leakage, which may cause serious complications, including severe headache, pseudomeningocele formation, nerve root entrapment, and intracranial hemorrhage. As a result, it contributes to higher healthcare costs and poor patient outcomes. The purpose of this study was to clarify the independent risk factors that can cause ID during posterior open spine surgery for degenerative diseases in adults. We conducted a prospective multicenter study of adult patients who underwent posterior open spine surgery for degenerative diseases at 10 participating hospitals from July 2010 to June 2013. A total of 4,652 consecutive patients were enrolled. We evaluated potential risk factors, including age, sex, body mass index, American Society of Anesthesiologists physical status classification, the presence of diabetes mellitus, the use of hemodialysis, smoking status, steroid intake, location of the surgery, type of operative procedure, and past surgical history in the operated area. A multivariate logistic regression analysis was performed to identify the risk factors associated with ID. The incidence of ID was 8.2% (380/4,652). Corrective vertebral osteotomy and revision surgery were identified as independent risk factors for ID, while cervical surgery and discectomy were identified as factors that independently protected against ID during posterior open spine surgery for degenerative diseases in adults. Therefore, we identified 2 independent risk factors for and 2 protective factors against ID. These results may contribute to making surgeons aware of the risk factors for ID and can be used to counsel patients on the risks and complications associated with open spine surgery.

Percutaneous endoscopic lumbar discectomy via adjacent interlaminar space for highly down-migrated lumbar disc herniation: a technical report

The treatment of highly migrated lumbar disc herniation (LDH) is a challenge for percutaneous endoscopic lumbar discectomy (PELD). The purpose of this study was to determine the feasibility and efficacy of PELD for highly migrated LDH via the adjacent interlaminar space. We performed PELD via the adjacent interlaminar space in three patients with radiculopathy caused by highly migrated LDH using a full-endoscopic system (diameter of working channel: 4.1 mm, outer diameter: 6.9 mm). One case had a large interlaminar bone window that did not require enlargement. Enlargement of the bone window in other cases was performed with a 3.5-mm diameter high-speed drill. After the operation, we confirmed pain relief and evacuation of migrated LDH on magnetic resonance imaging in all patients. The mean operative time was 75.3 min, and no complication was observed. PELD via the adjacent interlaminar space is an appropriate operative approach for highly down-migrated LDH. Minimal laminectomy using a high-speed drill is conductive to this approach.

Microendoscope-assisted posterior lumbar interbody fusion: a technical note

Background Various surgical options for lumbar interbody fusion have been reported. Minimally invasive techniques are widely used to reduce soft tissue damage. Here, we report our novel technique of microendoscope-assisted posterior lumbar interbody fusion (ME-PLIF) using an 18-mm tubular retractor system (METRx, Medtronic Sofamor Danek, Memphis, TN, USA) for lumbar spine degeneration treatment. Methods Between January 2011 and December 2011, 48 patients underwent one level ME-PLIF by a surgeon in our hospital. We followed up 46 patients (95.8%). A 20-mm skin incision was made in the craniocaudal direction at the level of the intervertebral disc, 15 mm outside the midline (symptomatic side). The surgeon placed the tubular retractor and performed decompression, thoroughly discarded the intervertebral disc, and then inserted the autologous crushed bone on the opposite side. Subsequently, a cage was inserted using fluoroscopic guidance. Following the end of the microendoscopic operation, pedicle screws (PS) were inserted percutaneously using fluoroscopic guidance. Clinical outcomes were evaluated using the Oswestry Disability Index (ODI) and the Japanese Orthopedic Association (JOA) scores. For radiological outcomes, fusion rates based on the Bridwell fusion grading system were evaluated using plain radiography or a computed tomography scan at the most recent follow-up timepoint. Results The mean age was 61.4 (range, 36.0-86.0) years, the mean operation time was 102 (range, 59-162) min, and the mean blood loss was 86 (range, small amounts-315) mL. The average pre- and post-operative ODI scores were 22.1 and 9.7, respectively, with an improvement rate of 56.1%, and the pre- and post-operative JOA scores were 9.8 and 16.4, respectively, with an improvement rate of 50%. There were no cases of pseudarthrosis. One case (2.2%) had a deep wound infection that required total removal of the implants. Four (8.7%) cases had a dural tear and required dural sutures under microendoscopy, though they had good recovery. Conclusions This technique yielded good results. The advantages of using only the microendoscope were: (I) better visual field and (II) higher operability (it was possible to change the tubular retractor to various angles; this was difficult under direct viewing or under a microscope). These features are considered to lead to reduce soft tissue damage. Although long-term follow-up results are needed, this appears to be a safe and minimally invasive treatment option for lumbar spine degeneration.

Risk factors for surgical site infection after lumbar laminectomy and/or discectomy for degenerative diseases in adults: A prospective multicenter surveillance study with registry of 4027 cases

Surgical site infection (SSI) is a significant complication after spinal surgery and is associated with increased hospital length of stay, high healthcare costs, and poor patient outcomes. Accurate identification of risk factors is essential to develop strategies to prevent wound infections. The aim of this prospective multicenter study was to determine the independent factors associated with SSI in posterior lumbar surgeries without fusion (laminectomy and/or herniotomy) for degenerative diseases in adult patients. From July 2010 to June 2014, we conducted a prospective multicenter surveillance study in adult patients who developed SSI after undergoing lumbar laminectomy and/or discectomy in ten participating hospitals. Detailed patient and operative characteristics were prospectively recorded using a standardized data collection format. SSI was based on the Centers for Disease Control and Prevention definition. A total of 4027 consecutive adult patients were enrolled, of which 26 (0.65%) developed postoperative SSI. Multivariate regression analysis indicated two independent factors. An operating time >2 h (P = 0.0095) was a statistically significant independent risk factor, whereas endoscopic tubular surgery (P = 0.040) was a significant independent protective factor. Identification of these associated factors may contribute to surgeons’ awareness of the risk factors for SSI and could help counsel the patients on the risks associated with lumbar laminectomy and/or discectomy. Furthermore, this study’s findings could be used to develop protocols to decrease SSI risk. To the best of our knowledge, this is the first prospective multicenter study that identified endoscopic tubular surgery as an independent protective factor against SSI after lumbar posterior surgery without fusion.

Different operative findings of cases predicted to be symptomatic discal pseudocysts after percutaneous endoscopic lumbar discectomy

Percutaneous endoscopic lumbar discectomy (PELD) is a minimally invasive treatment for lumbar disc herniation (LDH). This report focused on one of the rare complications of PELD: symptomatic postoperative discal pseudocyst (PDP). A 27-year-old male patient (case 1) presented with recurrent radiculopathy in his left leg. Twenty days previously, he had undergone PELD for left L4/5 LDH and his symptoms temporarily improved. A 14-year-old female patient (case 2) also developed recurrent pain in her left leg. Thirty days previously, she had undergone PELD for left L4/5 LDH and her symptoms disappeared. On the basis of the finding of an expandable round lesion at the evacuated sites of LDH on magnetic resonance imaging (MRI), with low intensity of T1-weighted imaging and high intensity on T2-weighted imaging, we predicted symptomatic PDP in both cases. Given the progressive leg pain in both cases, surgical treatments were adopted (case 1: microendoscopic discectomy, case 2: PELD). During the operation, we confirmed that case 1 was a simple recurrence of LDH and case 2 was symptomatic PDP. Previous studies on symptomatic PDP included cases diagnosed without operative findings. Therefore, it should be carefully considered that such cases might be a simple recurrence of LDH.