脊髄外科 Vol. 30(2016) No. 2

  Surgical treatment for spinal cord lesions carries a high risk of postoperative neurological deficits. Intraoperative neurophysiological monitoring has been developed to reduce such risks. Initially, somatosensory evoked potential (SEP) monitoring was successfully used in deformity correction surgery. Its major disadvantage was its inability to detect partial spinal cord damage affecting motor pathways. Motor evoked potential (MEP) monitoring was later developed to overcome this deficit of SEP monitoring. Both SEP and MEP monitoring were highly accurate in predicting postoperative neurological deficits in deformity correction surgery and were later introduced into surgery for intramedullary tumors (IMTs). These monitoring techniques provide accurate predictions in patients with intact neurologic function, but are prone to false positives when patients have compromised neurologic function. Some studies overemphasize the usefulness of intraoperative neurophysiological monitoring in surgical treatment for IMTs. We review the current understanding of neuroanatomy and physiology and the realistic utility and limitations of intraoperative neurophysiological monitoring during surgery for IMTs.

  Objective : Surgical site infection (SSI) caused by methicillin-resistant Staphylococcus aureus (MRSA) after spinal instrumentation surgery is often intractable, and removal of the implants is frequently necessary for infection control. Although vancomycin (VCM) has been most frequently used against SSI caused by MRSA, recent literatures questioned its efficacy because of its low tissue penetration. Some experts recommend combination therapy with anti-MRSA agents possessing higher tissue penetration or an anti-biofilm effect. The present report shows outcomes of antibiotic therapy for SSI caused by MRSA after spinal instrumentation surgery.

  Materials and methods : From January 2011 to December 2013, four patients developed SSI caused by MRSA after spinal instrumentation surgery. Posterior lumbar interbody fusion was used in all patients. As initial therapy, VCM was given to one patient, and combined teicoplanin (TEIC) and rifampicin (RFP) were administered to the other three. These patients subsequently received therapy with TEIC, linezolid, or daptomycin combined with RFP, sulfamethoxazole-trimethoprim, or clindamycin. These agents were stopped sequentially if C-reactive protein remained negative for more than a week.

  Results : Infection was uncontrolled in one patient initially treated with VCM, and removal of the posterior instrumentation and interbody cages was required for infection control. Combined therapy was given postoperatively, with complete cure by 13 weeks after removal of the implants. Infection was controlled and the implants could be retained in the other three patients who were initially treated with TEIC and RFP ; cure was achieved with subsequent combined therapy for 3-15 weeks.

  Conclusion : The present study suggests that SSI caused by MRSA is treatable with retention of the implant by using combined therapy with anti-MRSA agents possessing higher tissue penetration than VCM or those with an anti-biofilm effect.

  Object : We experienced 20 cases treated with X-STOP PEEK^® for lumbar spinal canal stenosis, and report their preliminary results.

  Materials and Methods : Twenty patients underwent insertion of an interspinous spacer (X-STOP PEEK^®) for lumbar spinal canal stenosis, and postoperative neurological symptoms, Japanese Orthopedic Association (JOA) score, cross-sectional area of the spinal canal, and the height of the inter-vertebral space were evaluated.

  Results : Of the 20 patients, 15 were males and 5 were female, and their age at operation was 53 to 82 years (mean : 73 years). The follow-up period was 12 to 38 months (mean : 24 months). The pre-operative JOA score was 4 to 15 (mean : 9.9), the 1-month post operative JOA score was 20 to 26 (mean : 24), and the JOA score recovery rate (R. R. %) was 61% to 96% (mean : 75%). The 1-year postoperative JOA score was 9 to 26 (mean : 23), and the R. R. was 13% to 96% (mean : 70%). The preoperative cross-sectional area of the spinal canal was 2.1 mm² to 6.1 mm² (mean : 4.2 mm²) and the inter-vertebral space was 3.2 mm to 5.5 mm (mean : 4.3 mm) ; the 1-year postoperative cross-sectional area of the spinal canal was 4.0 mm² to 9.4 mm² (mean : 6.1 mm²) and the inter-vertebral space was 4.5 mm to 8.7 mm (mean : 7.2 mm). One case (5%) had neurological deterioration due to fracture of a spinous process and dislocation of the X-STOP, and required conventional posterior decompression one year later ; two other cases (10%) had a fractured spinous process, of which one had neurological deterioration. No peri-operative complicationa occurred.

  Conclusion : Insertion of an interspinous spacer (X-STOP PEEK^®) for lumbar spinal canal stenosis improved the JOA score by increasing the cross-sectional area of the spinal canal and the inter-vertebral space at the 1-year follow-up. However, the effectiveness was slightly decreased on long-term follow-up. Fracture of the spinous process between the levels at which X-STOP was inserted induced neurological deterioration. Case selection should include those without an indication for conventional decompression surgery, to ensure cost-effective management.

  Objective : Lumbar foraminal or extraforaminal lesions account for 8-11% of all cases of lumbar canal stenosis. There is no consensus on the preferred surgical procedure for these lesions. To obtain adequate decompression of the nerve root, the partial or total removal of the facet joint is necessary. Some surgeons use decompression surgery alone, while others advocate the decompression procedure combined with spinal fixation.

  The authors retrospectively investigated the results of surgery for lumbar foraminal or extraforaminal lesions at our institute.

  Methods : Between January 2006 and December 2013, 86 patients with lumbar foraminal or extraforaminal lesions underwent surgery in our institute. Patients with reoperation, multiple level lesions, and spondylolysis were excluded from this study. The minimum postoperative follow-up time was 1 year. The Japanese Orthopedic Association (JOA) score and visual analogue scale (VAS) for back and leg pain were evaluated pre- and postoperatively. Dynamic slip angle, dynamic slip distance, and Cobb angle were measured by using standing X-ray films pre- and postoperatively. Patients with≧10° preoperative Cobb angle were defined as the “DLS group” and those with<10° were defined as the “non-DLS group” .

  Results : The preoperative JOA score (14.2) and VAS for back (5.4) and leg pain (6.9) were significantly improved to 20.7, 3.0, and 2.5, respectively, at 1 year after surgery. Postoperative progression of scoliosis (≧5°) occurred in 27.3% of the DLS group, which was higher than that in the non-DLS group (p=0.028). In the non-DLS group, no significant difference in the JOA score or VAS improvement rate was noted between the various operative procedures. On the contrary, in the DLS group, the JOA score improvement ratio was worse in patients who underwent decompression surgery alone than in patients who underwent spinal fixation. The Cobb angle increased significantly in patients who underwent decompression surgery alone and in those with unilateral pedicle screw fixation, compared with those who underwent interbody fusion and bilateral pedicle screw fixation.

  Conclusion : Microscopic decompression surgery alone can achieve satisfactory results for patients with foraminal or extraforaminal lesions when spinal instability or scoliosis (Cobb angle≧10°) is not apparent. On the other hand, patients with scoliosis have the potential risk of postoperative progression of scoliosis with a poor outcome. The authors recommend adequate decompression combined with interbody fixation and bilateral pedicle screw fixation for patients with DLS (Cobb angle≧10°).

  Ankylosing spinal hyperostosis (ASH) is characterized by the presence of anterior cervical osteophytes. Although osteophytes in ASH are generally asymptomatic, large osteophytes sometimes can cause dysphagia. We report a case of ASH with dysphagia that rapidly became exacerbated after a seizure.

  A 65-year-old man was brought to the emergency department with traumatic brain injury. After conservative treatment, he was discharged home. Six months later, he was again brought to the emergency department with a convulsive seizure. He was diagnosed with symptomatic epilepsy and was hospitalized. After admission, he was seizure-free. Although he regained consciousness after admission, he experienced severe dysphagia and developed aspiration pneumonia. Computed tomography demonstrated anterior cervical osteophytes from the C2 to the C7 levels. Further examination did not reveal any other coexisting diseases that could affect the swallowing function. These osteophytes were diagnosed as the cause of dysphagia and he underwent rehabilitation. However, his swallowing function did not improve and surgical resection of the osteophytes was performed. After the procedure, his swallowing function improved and he was transferred to another hospital for rehabilitation.

  Dysphagia caused by ASH progresses slowly in most cases. In this case, dysphagia rapidly became exacerbated after a seizure. Subclinical dysphagia caused by ASH had led to chronic undernourishment. Following the seizure, the patient was bedridden for several days. This caused severe muscle atrophy and resulted in rapid exacerbation of dysphagia.

  This is the first report of ASH with dysphagia that rapidly became exacerbated after a seizure. It is important to recognize that subclinical dysphagia caused by ASH can become worse after a short period of being bedridden, as it is often associated with chronic undernourishment.