Introduction : Spinal arteriovenous fistula (AVF) is a relatively rare spinal disorder that requires surgical interruption. However, there is a high risk of spinal cord damage during the surgery, especially in the ventral lesions. The purpose of this study was to evaluate the efficacy of intraoperative motor evoked potential (MEP) monitoring for spinal AVF.
  Methods : We analyzed data of 22 patients with perimedullary AVF and 14 patients with dural AVF retrospectively. MEPs were recorded by transcranial electrical stimulation and compound muscle action potentials. General anesthesia was maintained using propofol and remifentanil.
  Results : MEPs deteriorated during the surgery in 6 of 42 operations for perimedullary AVF ; 3 were transient, but 3 were not recovered during the surgery. These latter cases showed postoperative motor deterioration. However, there was no deterioration of MEPs and postoperative course in dural AVF patients.
  Conclusions : Intraoperative MEP monitoring is an effective and reliable method in spinal AVF surgery.

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  Objective : In order to decompress the spinal canal in lumbar spinal canal stenosis, we have used reposition type of spinous process splitting posterior decompression using a tubular retractor (METRx^® quadrant system). Conventional surgery may cause abnormality of the lumbar sagittal alignment which may result in postoperative lumbago, and its treatment is difficult. The aim of this study was to compare lumbar spinal sagittal alignment and clinical results between our surgical method and conventional laminectomy for lumbar spinal canal stenosis.
  Methods : Surgical technique : After making a 2.5-cm skin incision, the spinous process was split and a tubular retractor (METRx^® quadrant system) was inserted. Following a neurodecompression, the separated spinous processes was reconstructed at their base in the laminae.
  We observed postoperatively 100 patients (women, 54 ; men, 46 ; average age, 69.2 years) who underwent our surgical method between January 2009 and March 2012. Patients were followed up for more than one year after surgery.
  The clinical evaluation was determined by the Japanese Orthopaedic Association (JOA) score (15 points) and the presence of lumbar spinal lordosis and instability in radiography images.
  Results : The improvement rate of the JOA score and lumbago was 82% and 84.0%, respectively. The postoperative radiography findings revealed that the union rate of the reconstructed spinous process and the bases was 87% at 12 months.
  Conclusion : The surgical results of this procedure were satisfactory with only minor postoperative lumbago. In decompression of the spinal canal in lumbar spinal canal stenosis, preservation of the back muscles, and reconstruction of the spinous process are crucial for satisfactory postoperative lumbar spinal lordosis. Our surgical method is effective in the reduction of postoperative lumbago.

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  Spinal hemangioblastomas are benign, and total surgical resection is the standard treatment method used. However, hypervascular tumors may have excessive operative blood loss if the tumors are divided. We encountered a case of cauda equina hemangioblastoma with extraordinary blood supply, which was treated with preoperative embolization. A 49-year-old woman with von Hippel-Lindau disease who had undergone multiple surgeries for intracranial/extracranial hemangioblastomas had lumbago and leg pain. Magnetic resonance images revealed intradural spinal tumors at the L4-S1 vertebral level, with remarkable gadolinium enhancement. The patient was referred to our hospital, after a plan of total resection had been abandoned elsewhere because of the high flow feeders and high pressure of the tumors. Preoperative embolization was performed with consequent disappearance of the arterial blood supply to the tumor. Two days later, the tumor was resected subtotally with reduced tension and a little blood loss. The patient’s symptoms resolved soon after surgery. Selective preoperative embolization for a spinal hemangioblastoma with a rich blood supply is a valid option as an adjuvant to the complete surgical resection of a tumor.

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  A 39-year-old man presented with severe pain in the buttocks and increased difficulty in walking. Magnetic resonance (MR) images revealed a cystic lesion at the S1-2 vertebral level, which was diagnosed as a sacral perineural cyst. A fistula was noted between the thecal sac and the cyst by contrast filling of the cyst at an early phase on myelography and post-myelographic computed tomography (CT). Based on these findings, the patient underwent surgical closure of sacral perineural cyst fistula. Following the surgery, the patient’s symptoms disappeared.
  Symptomatic sacral perineural cysts are uncommon, but sometimes require surgical treatment. In this patient, closing the fistula between the cyst and the thecal sac was effective in resolving the cyst and obtaining a clinical cure.

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  Objective : Technical modifications may be mandatory to safely remove high cervical tumors with ventral or lateral extension. We present our surgical experience with a lateral approach to these tumors and discuss the surgical indications and avoidance of complications.
  Methods : Six patients with spinal tumors in a ventral or lateral location of the high cervical spine were included. Three of the 6 cases had intradural tumors including meningiomas and synovial cysts, and 3 cases had extradural tumors including a schwannoma, clear cell carcinoma, and plasmacytoma. The patients were placed in the lateral park-bench position. A retroauricular incision exposed the transverse process of C1.
  Subperiosteal muscle dissection exposed the lateral parts of C1 and C2 and the suboccipital condylar fossa. The vertebral artery running in the vascular groove of C1 was well recognized. The horizontal segment of the vertebral artery can be transposed by opening the C1 transverse foramen, if necessary.
  Results : A high cervical lateral approach allowed access to the ventral aspect of the spinal cord with little or no retraction. The exposure was straightforward and provided a relatively narrow but shallow operative field. The vertebral artery could be identified early in the exposure. No case experienced major postoperative surgery-related complications.
  Conclusion : A high cervical lateral approach can be applied successfully in selected cases, such as those with a tumor with ventral or lateral extension. Safe management of the vertebral artery is one of the key considerations.

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