Objective : Postoperative epidural drainage is commonly encountered during spinal instrumentation surgery. However, the significance of postoperative drainage remains unclear. Herein, we attempted to clarify the significance of postoperative drainage based on drainage fluid content and volume.

  Materials and Methods : We study including 107 posterior lumbar interbody fusion cases which was conducted from March 2014 to December 2018. Postoperative drainage volumes were measured every 6 h for each patient. Blood analysis of the drainage fluid was performed for 67 patients. Blood cell counts (red blood cells, white blood cells, platelets, and segments of white blood cells), total protein, albumin levels, and albumin-to-globulin ratios were determined in each drainage bag. Bags 1, 2, and 3 represent drainage volumes collected<12, 12-36, and>36 h, respectively. One patient had a subcutaneous effusion, and the aspirate was analyzed like the drainage fluid.

  Results : The drainage volume increased rapidly (40 ml/h) within the first 12 h after surgery, gradually decreased by 15 ml/h between 12 and 36 h, and further decreased by 8 ml/h after 36 h. Blood analysis revealed a significant decrease in all blood cell lineages. Total protein and albumin levels decreased after Bag 3 collection. In the patient with a subcutaneous effusion, the aspirate showed a higher white blood cell count, platelet count, total protein level, and albumin level than the postoperative drainage.

  Conclusion : Based on drainage fluid and volume analyses, the drainage volume gradually decreased with time and the drainage fluid contents converted blood cells into interstitial fluid after 12 h.

  Introduction : We classified Chiari malformation typeⅠ (CM-Ⅰ) according to the pathogenesis of ptosis of the brain stem and cerebellum based on morphometric analyses of the posterior cranial fossa (PCF) and craniovertebral junction. Three independent subtypes were confirmed―CM-ⅠTypes A, B, and C. CM-Ⅰtype B is characterized by a normal PCF volume (PCFV), small volume of the area surrounding the foramen magnum (VAFM), and a small occipital bone size. CM-ⅠType C is characterized by a small PCFV, small VAFM, and occipital bone size. CM-ⅠType A (other pathogenesis) is characterized by conditions such as craniocervical instability and tethered cord syndrome. We examined the pathogenesis of ptosis of the brain stem and cerebellum and reported the preliminary outcomes of each surgical approach.

  Materials and Methods : Foramen magnum decompression (FMD ; 207 cases) was performed for CM-ⅠType B and CM-Ⅰborderline cases. Expansive suboccipital cranioplasty (ESCP ; 128 cases) was performed for CM-ⅠType C cases. We examined neurological symptoms and determined the Japanese Orthopaedic Association (JOA) scores. Cerebrospinal fluid (CSF) flow dynamics were assessed pre- and post-surgery using cine phase-contrast magnetic resonance imaging (MRI). During surgery, CSF flow dynamics were examined using color Doppler ultrasonography (CDU).

  Results : ESCP and FMD showed a high improvement rate for neurological symptoms and a high recovery rate of the JOA score (77.5%). Craniocervical fixation showed a high improvement rate for neurological symptoms (89%) and a high recovery rate of the JOA score (76.9%). Lysis and/or section of the filum terminale (SFT) and ventriculoperitoneal shunt (VPS) placement exhibited a low improvement rate for neurological symptoms (35-40%). The maximum CSF flow velocity (cm/s) was significantly lower preoperatively than in controls and increased postoperatively. There were no significant differences in the percentages of cardiac cycles. During surgery, CDU indicated that the volume of the cisterna magna was 8 ml and the maximum flow velocity was>3 ml/s.

  Conclusions : In the management of CM-Ⅰ, an appropriate surgical method that addresses the ptosis of the brain stem and cerebellum should be chosen. ESCP is appropriate for cases with a small PCFV. FMD is suitable for cases with a normal PCFV and small VAFM. However, other approaches should be considered for CM-ⅠType A (other pathogenesis). For CM-Ⅰ, lysis and/or SFT and VPS are not the only available surgical methods, and FMD or ESCP should be considered.

  Purpose : Anterior cervical disc replacement (ACDR) was included in the medical insurance authorization in our country in December 2017. Prestige LP and Mobi-C implants were accepted in the United States several years ago. We expect a decrease in the risk of developing a disorder in the mid- and long-term fixed adjacent segment disease of ACDR, in addition to being a cost-effective method in this country. The safety and efficacy of ACDR should always be considered.

  Case presentation : We present the case of a patient who underwent ACDR this time in a certain country and reported our experience of dislocation of Mobi-C after 3 months post-surgery.

  Results : The following causes of dislocation of Mobi-C were considered : 1. size incompatibility in ACDR ; 2. narrowing of the intervertebral disc of the patient ; 3. destruction of the osseous end plate ; 4. error of the ACDR insertion method ; and 5. insufficiency of decompression. The causes of dislocation of Mobi-C were always expected ; therefore, close attention must be paid.

  Conclusions : Nerve decompression in the surgical procedure, preservation of the osseous end plate, and the optimal size of the artificial intervertebral disc and setting are important factors for dislocation in ACDR.

  Takotsubo cardiomyopathy is often triggered by an intense physical or emotional event ; it is rarely seen in patients with spinal disease. We experienced a case of takotsubo cardiomyopathy triggered by a vertebral compression fracture. A 75-year-old woman was admitted to our hospital with complaints of low back pain that developed after a fall. X-ray and computed tomography images revealed an L1 vertebral compression fracture. Magnetic resonance imaging demonstrated a fresh fracture on the L1 vertebral body. She was treated conservatively ; however, as her low back pain worsened, balloon kyphoplasty (BKP) was planned. Pre-operative electrocardiography demonstrated ST elevation in multiple leads, and transthoracic echocardiography revealed ventricular asynergy. Acute coronary syndrome was suspected, and an urgent coronary angiography was performed. There was no coronary artery stenosis, but akinesis of apical wall was detected. The patient was diagnosed with takotsubo cardiomyopathy without chest pain or dyspnea. She had an uneventful course without cardiac complications, such as cardiac failure and arrhythmia. BKP was performed safely, after which her low back pain was relieved. She was discharged on the 27^th postoperative day.

  To the best of our knowledge, this is the first report of a patient with a vertebral compression fracture accompanied by takotsubo cardiomyopathy. Takotsubo cardiomyopathy is a rare and transient cardiomyopathy. However, once cardiac complications occur, it occasionally leads to a fatal condition. In fact, the mortality rate of takotsubo cardiomyopathy is comparable to that of acute coronary syndrome. Prevention and early detection of takotsubo cardiomyopathy are important. Cardiac examination is recommended even in cases of compression fracture or physical or emotional stress.

  Calcification of ligamentum flavum (CLF) is a degenerative spinal disease in which calcium crystals deposit in the ligamentum flavum. The CLF may cause spinal cord compression, and the patient may need decompressive surgery. However, CLF can spontaneously regress with some medications as well as no treatment. Here, the authors reported a case in which small CLF remaining after cervical decompression surgery markedly enlarged during the follow-up period and spontaneously regressed after pregabalin administration. Therefore, pregabalin might be involved in the spontaneous regression of CLF.

  A 66-year-old female complaining of right upper limb pain and numbness was diagnosed with CLF at C5/6 and C6/7 by computed tomography (CT) and magnetic resonance imaging (MRI). The symptoms improved after removal of the CLF at C5/6 with C5 laminectomy and C4, C6 laminoplasty. Postoperative CT showed small residual CLF at C6/7. Six years after surgery, she suffered pain and numbness in her right arm. Her cervical MRI showed a marked increase of CLF at C6/7. The pain disappeared after the administration of pregabalin. Six months later, a marked reduction of CLF was observed on MRI.

  It has been reported that the administration of cimetidine or etidronate resulted in the regression of CLF. Cimetidine affects calcium metabolism via parathyroid hormone (PTH), and etidronate has an inhibitory effect on calcification. It was reported that the serum PTH was markedly reduced in a uremic patient after the administration of pregabalin. The efficacy of pregabalin was also reported for a case with refractory paroxysmal kinesigenic choreoathetosis whose parathyroid glands were removed. It is presumed that pregabalin was involved in calcification regression via PTH metabolism in this case.

  A 64-year-old man presented with a two-month history of slowly progressive pain in the right lower extremity. T2-weighted magnetic resonance imaging showed a high-intensity lesion in the conus medullaris, multiple subarachnoid signal voids surrounding the conus medullaris and cauda equina, and lumbar canal stenosis at L3/4 and L4/5 levels. Selective spinal angiography of the left eleventh segmental artery showed the anterior spinal artery (ASA), which was connected to the feeding artery and draining into the enlarged tortuous vein. The feeding artery was connected to the fistula at the L5/S1 level. We regarded the feeding artery as the artery of the filum terminale, and a tentative diagnosis of arteriovenous fistula (AVF) of the filum terminale was made. Surgery with laminoplasty was performed from L4-L5 to open the dura mater. The cauda equina, including abnormal vessels, was exposed immediately on placing the dural incision. It was noted that the feeding artery was not the artery of the filum terminale. It was confirmed to be the proximal radicular artery, the fistula, and the draining vein on the cauda equina nerve root, which were resected. The AVF completely disappeared. After surgery, he demonstrated improvement in symptoms. MRI recorded six months postoperatively revealed marked improvement of the high intensity intramedullary signal and complete disappearance of the abnormal flow void.

  Identification of the AVF of the cauda equina fed by the proximal radicular artery is essential for the successful obliteration of the fistula. The AVF with a single shunt point of the cauda equina could be completely occluded through direct surgery, without major complications.

  Myelopathy caused by ossification of the posterior longitudinal ligament (OPLL) combined with ossification of the yellow ligament (OYL) at the same level is not rare, but surgical management of this lesion is controversial. We reported four cases and reviewed the literature on surgical therapy.

  Case 1 : A 42-year-old man developed severe transverse cord syndrome up to T3, with a Japanese Orthopaedic Association (JOA) score of 3. Computed tomography (CT) and magnetic resonance imaging (MRI) demonstrated OPLL and OYL in the upper and middle thoracic spine. Laminectomy of T2, 3, and 4 were performed. Post-op 6 month JOA score recovery rate (RR) was 25.0%.

  Case 2 : A 48-year-old man developed severe transverse cord syndrome up to T5 with a JOA score of 6. CT and MRI demonstrated OPLL and OYL in the middle thoracic spine. Laminectomy of T4-5 was performed. Post-op 6 months RR was 44.4%.

  Case 3 : A 67-year-old woman developed severe transverse and Brown-Séquard type myelopathy up to T5, JOA score of 6. CT and MRI demonstrated OPLL and OYL in the middle thoracic spine. Laminectomy of T3-4 and laminoplasty for T5, 6, and 7 were performed. Post-op 6 months RR was 60.0%. Kyphosis deteriorated.

  Case 4 : A 45-year-old woman developed severe transverse and Brown-Séquard type myelopathy up to T3, JOA score of 5. CT and MRI demonstrated OPLL and OYL in the upper and middle thoracic spine, respectively. Laminoplasty for T3, 4, 5 and posterior lateral fixation (PLF) for T5/6/7 were performed. Post-op 6 months RR was 85.7%.

  The ossificaion-kyphosis angle was useful in deciding the operative indication. One-staged posterior decompression and fixation should be considered in patients with long lesions and kyphosis. Careful long-term follow-ups are necessary.