Objective : Oblique lateral interbody fusion (OLIF) is becoming the preferred treatment for degenerative lumbar diseases. As beginners, we performed 143 surgeries over 19 months. In these consecutive cases, we analyzed the learning curve and reviewed the complications in our experience. Methods : This was a retrospective study; however, complications that were well known in the previous literature were strictly recorded prospectively. We followed up the changes in estimated blood loss (EBL), operation time, and transient psoas paresis according to case accumulation to analyze the learning curve. Results : Complication-free patients accounted for 43.6% (12.9%, early stage 70 patients and 74.3%, late stage 70 patients). The most common complication was transient psoas paresis (n=52). Most of these complications occurred in the early stages of learning. C-reactive protein normalization was delayed in seven patients (4.89%). The operation time showed a decreasing trend with the cases; however, EBL did not show any significant change. Notable operation-induced complications were cage malposition, vertebral body fracture, injury to the ureter, and injury to the lumbar vein. Conclusion :According to the learning curve, the operation time and psoas paresis decreased. It is important to select an appropriately sized cage along with clear dissection of the anterior border of the psoas muscle to prevent OLIF-specific complications.

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The duplicated middle cerebral artery (DMCA) is an anatomic variation that arises from the distal internal carotid artery (ICA) and supplies blood to the middle cerebral artery (MCA) territory. Aneurysms of the DMCA have been reported in 36 cases in 2020. We also report a case of a 3.7 mm saccular aneurysm originating from the DMCA. A 52-year-old woman visited our hospital with worsening headache. She had no neurological abnormalities. Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) revealed a right distal ICA aneurysm at the anterior choroidal artery. Cerebral angiography was performed to confirm the shape and the size of the aneurysm. Cerebral angiography revealed that the vessel that was originally identified as the anterior choroidal artery by the MRA was actually the duplicated MCA that was originating from the aneurysm neck and was supplying the MCA territory. The patient's aneurysm was clipped using a transsylvian approach and she recovered without any neurological symptoms. DMCAs are rare and often associated with aneurysms and require preoperative evaluation to confirm the vascular status, aneurysm characteristics, and the shape of the parent artery.

Meningiomas are primary benign tumors that occur in intracranial and intraspinal regions. Rarely, atypical and anaplastic meningiomas exhibit malignant tendencies and can metastasize. A 56-year-old female patient visited the hospital complaining of a dull headache, mild dysarthria, sudden onset of blurred vision, and mild weakness in the left upper limbs. A homogeneously augmented mass was revealed in the right temporal lobe following magnetic resonance imaging (MRI) and was determined to be an anaplastic meningioma after surgical resection. During follow-up, revision surgery was performed due to the recurrence of the primary tumor. After the revision surgery, the patient complained of new symptoms, which included paresthesia and muscle weakness in the right lower extremity. MRI revealed a mass in the cervical and lumbar vertebrae suspected to have been metastasized. Another revision surgery was conducted on the intracranial primary tumor. The tumor was resected from the cervical and lumbar vertebrae. Histopathology revealed that they were all anaplastic meningiomas. Although anaplastic meningioma is rare, it can cause extracranial metastases. This case shows that multiple spinal metastases of anaplastic meningioma require considerable attention in diagnosis and treatment.