Standard Microsurgical Techniques Research Articles

Arterial Bypass in the Treatment of Complex Middle Cerebral Artery Aneurysms: Lessons Learned from Forty Patients

Complex middle cerebral artery (MCA) aneurysms incorporating parent or branching vessels are often not amenable to standard microsurgical clipping or endovascular embolization treatments. We aim to discuss the treatment of such aneurysms via a combination of surgical revascularization and aneurysm exclusion based on our institutional experience. Thirty-four patients with complex MCA aneurysms were treated with bypass and aneurysm occlusion, 5 with surgical clipping or wrapping only, and 1 with aneurysm excision and primary reanastomosis. Bypasses included superficial temporal artery (STA)-MCA, double-barrel STA-MCA, occipital artery-MCA, and external carotid artery-MCA. After bypass, aneurysms were treated by surgical clipping, Hunterian ligation, trapping, or coil embolization. The average age at diagnosis was 46 years. Of the aneurysms, 67% were large and most involved the MCA bifurcation. Most bypasses performed were STA-MCA bypasses, 12 of which were double-barrel. There were 2wound-healing complications. All but 2 of the aneurysms treated showed complete occlusion at the last follow-up. There were 3 hemorrhagic complications, 3 graft thromboses, and 4 ischemic insults. The mean follow-up was 73months. Of patients, 83% reported stable or improved symptoms from presentation and 73% reported a functional status (Glasgow Outcome Scale score 4 or 5) at the latest available follow-up. Cerebral revascularization by bypass followed by aneurysm or parent artery occlusion is an effective treatment option for complex MCA aneurysms that cannot be safely treated by standard microsurgical or endovascular techniques. Double-barrel bypass consisting of 2 STA branches to 2 MCA branches yields adequate flow replacement in most cases.

Burr Hole Microsurgery for Middle Cerebral Artery Aneurysms: A Clinical Case Series

BACKGROUND: Minimally invasive microsurgery has become popular in neurosurgery. Burr hole microsurgery is another more modern minimally invasive technique that allows surgical treatment of various intracranial pathologies through an extreme small craniotomy. This article presents the first application of the burr hole approach for microsurgical clipping of cerebral aneurysms. OBJECTIVE: To assess the feasibility and outcomes of using the burr hole microsurgical technique in cerebral aneurysm surgery. METHODS: From March 2020 to August 2020, 3 patients with unruptured middle cerebral artery aneurysms underwent burr hole microsurgical clipping. RESULTS: Three patients with middle cerebral bifurcation aneurysms were successfully treated. The duration of surgery was from 62 to 83 min (median 72.5). Postoperatively, no new neurological symptoms, complications, or mortality were observed in all the cases. CONCLUSION: Burr hole microsurgery is an advanced neurosurgical method. Although the surgery is performed through a small burr hole approximately 14 mm in size, safe and successful treatment of normal-sized middle cerebral artery aneurysms using standard microsurgical principles and technique is possible.

Complex Intracranial Aneurysms.

Complex intracranial aneurysms remain challenging to treat using standard microsurgical or endovascular techniques. These aneurysms often require a combination of deconstructive and reconstructive procedures, such as parent artery occlusion, flow alteration, and blind-alley formation with or without bypass surgery, for effective and enduring therapeutic effects. It is important to determine the type of bypass based on the site of occlusion of the patent artery, anatomical features of the distal vessels, and expected adequate blood flow. In this chapter, we describe the "Standards," "Advances," and "Controversies" in the context of a microsurgical treatment strategy for complex intracranial aneurysms. "Standards" include a combination of frequent and commonly used procedures that have been gathering a certain consensus on their effectiveness. "Advances" include infrequent, demanding, and/or uncertain surgical procedures that are currently under debate. Finally, "Controversies" discuss a number of unsolved issues.

Influence of neodymium laser radiation on the frequency of recurrence and continued growth of extramedullary tumors

Objective. To assess the effect of neodymium laser radiation on the recurrence rate and continued growth of primary extramedullary tumors on the basis of clinical data obtained in the long-term follow-up period in operated patients with extramedullary tumors.Material and Methods. The long-term results of surgical treatment of two groups of patients (n = 412) with primary extramedullary tumors operated on from 1998 to 2014 were studied and systematized. Patients of comparison group (n = 277; 67.2 %) underwent removal of tumors using standard microsurgical techniques, and the neoplasms in patients of the study group (n = 135; 32.8 %) were removed with additionally used neodymium (Nd:YAG) laser.Results. The use of the developed laser technologies for the resection of extramedullary intracanal primary tumors made it possible to reliably reduce the relative number of recurrence and continued growth from 11.1 % to 1.2% compared with patients treated with standard surgery methods. The proportion of recurrences was 3.5 %, all of them were detected only in the group with the classical technique of tumor resection (p <0.01).Conclusion. The use of a neodymium laser as an additional technology to the classical microsurgical resection of extramedullary tumors is effective for the prevention of their recurrence and continued growth.

Preparation of three-notochord explants for imaging analysis of the cell movements of convergent extension during early Xenopus morphogenesis.

We describe a method of generating three-notochord explants to analyze the cell movements of convergent extension (CE) during Xenopus laevis gastrulation and neurulation. This method uses standard microsurgical techniques under a fluorescence stereomicroscope to combine notochordal sectors of gastrulae, side by side (lateral surfaces apposed) into a single explant. Three-notochord explants cultured on bovine serum albumin (BSA)-coated glass converged mediolaterally and extended in the anterior-posterior direction. The individual notochordal cells showed the mediolaterally oriented, bipolar tractional motility and the resulting mediolaterally oriented cell intercalation characteristic of CE, thereby reproducing both the in vivo tissue and the cell movements in an explant. Image analysis of three-notochord explants reveals the effects of overexpressions or knockdowns of genes, of manipulation of the extracellular matrix, and of exposure to chemical reagents on morphogenesis during gastrulation and neurulation, compared with control explants. Moreover, since three-notochord explants provide two zones of cell intercalation between notochords, individual cell behaviors between notochords of different characteristics and experimental treatments can be observed at the same time.

Navigated Endoport in the Purely Endoscopic Microsurgery of Intraventricular and Other Deep-Seated Brain Lesions: A Case Report

<p><strong>Objective. </strong>Brain parenchyma retraction is often necessary to reach various deep brain lesions during surgery. In order to minimise the incidence of the brain retraction injury, an endoport system may be employed. We present a report of a navigated endoport system in conjunction with an purely endoscopic microsurgery that was used in a patient with a deep-seated subependymoma.</p><p><strong>Case Report. </strong>A navigated endoport with purely endoscopic microsurgery were used in a patient with a tumour</p><p>located in the frontal horn of the left lateral ventricle. The endoport channel was made of a polyvinyl sheet that was cut into a 7 cm square, rolled into a tubular structure that was wrapped around the neuronavigational probe, and inserted in the access trajectory to the tumour. The endoport tube was then expanded with a balloon to a diameter of 7 mm and a surgical corridor was thus formed. During the purely endoscopic microsurgical lesionectomy, the tumour was completely removed from the frontal horn. The foramen of Monro was released and the septum pellucidum was perforated for better cerebrospinal fluid circulation. Histopathological examination confirmed the tumour as subependymoma. The recovery of the patient was unremarkable.</p><p><strong>Conclusion. </strong>The expandable endoport system supplemented with neuronavigation is a safe and efficient option for deep-seated tumour removal. The tubular shape of the retractor enables standard microsurgical techniques through minimally invasive approaches and offers an excellent visualization of the underlying lesion.</p>

Microscopic Antegrade Parotidectomy for Different Types of Parotid Tumor

Introduction: Salivary gland tumor accounts for about 5% of all the neoplasms of the head and neck. 75% of such tumors occur in the parotid glands. Pleomorphic adenoma is the most common type of benign salivary gland tumor. It tends to recur after inappropriate treatment. Surgery of parotid tumor includes enucleation, superficial parotidectomy and total parotidectomy. Identification and preservation of facial nerve trunk and its branches are very important in parotid surgery. Advancement of microsurgical technique has helped in better visualization, identification and preservation of the facial nerve. Methods: This prospective study included twenty-seven patients. Preoperative ultrasonography and fine needle aspiration cytology were done for all cases. Computed tomography/magnetic resonance imaging were performed in some cases when needed. Standard microsurgical technique with the help of microscope was performed for antegrade parotidectomy. Data analysis was done using SPSS version 26.0. Results: The patients' age ranged from 12 to 78 years. Fifteen (55.6%) patients were female and 12 (44. 4%) were males. Sixteen (59.3%) tumors were located on the right side whereas 11 (40.7%) were on the left side. Most of the tumors (n=18, 66.7%) were pleomorphic adenoma. Two (7.4%) of the patients had temporary facial paralysis which improved with time. Two (7.4%) patients had developed hematoma. Frey’s syndrome was not found in follow-up. Conclusion: This study showed low morbidity in parotidectomy using microsurgical techniques. No permanent injury to the facial nerve was found.

Paraplegia as a Severe Presentation of an Unusual Form of Ossified Intradural Meningioma: Case Report

Ossified meningioma is a rare type of intradural, extramedullary spinal meningioma which may give a bone density in the spinal canal and complicate surgical removal of the meningioma. This report discusses a case of ossified meningioma in a 60-year-old female patient who presented with paraplegia and uncontrolled urination and defecation. The condition had first appeared 2 years before as insidious thoracic spine pain with a progressive course; at that point, the patient was treated using traditional medicine. Thoracic computed tomography (CT) was conducted, and the results showed an intradural extramedullary calcified spinal tumour causing severe compression of the spinal cord at the level of thoracic vertebrae 8 (T8) and 9 (T9). Spinal magnetic resonance imaging (MRI) confirmed an intradural tumour at the T8 and T9 levels that was causing severe compression of the spinal cord. Total tumour resection was done using standard microsurgical techniques, and histopathological examination results confirmed the final diagnosis of meningioma. In conclusion, in cases like this, correct preoperative diagnosis and planning makes surgery easier and prevents neurological injury. Medical imaging using CT and MRI plays an essential role in this diagnosis and planning the management of ossified meningioma.

Sphenoid Ridge Keyhole Approach Using the Lone Star Retractor System in Clipping of Unruptured Middle Cerebral Artery Aneurysms: Technical Note

We report a technique for the sphenoid ridge keyhole approach using the Lone Star (LS) retractor system as an extracranial tissue retractor in microsurgical clipping of unruptured middle cerebral artery aneurysms. The LS retractor system is used as the extracranial tissue retractor. A skin incision (50-60 mm) without shaving is made. The temporal fascia is cut, and skin and fascia flap are reflected anteriorly. On the temporal muscle, keyhole craniotomy is registered using the navigation system such that the lateral edge of the sphenoid ridge is the center of the craniotomy. After the temporal muscle is split in the direction of the muscle fiber, keyhole craniotomy of approximately 30 mm in diameter is created. After dural incision, the Sylvian fissure is dissected by a standard microsurgical technique using brain retractors, and the target aneurysm is clipped. By precise registration of the sphenoid ridge keyhole craniotomy, the Sylvian fissure emerged in the center of the keyhole. Using the LS retractor system, a flat and shallow operative field was obtained. There were no complications using this method. We optimized the craniotomy, manipulating the target aneurysm in the center of the keyhole. It did not interfere with conventional microsurgical techniques.

Schwannomas of the sciatic nerve: A rare and neglected diagnosis. A review of the literature with two illustrative cases

ObjectiveSchwannomas of the sciatic nerve, which is the largest nerve of the human body, are very rare accounting for ≤ 1% of all schwannomas. They often may raise confusion with other more common causes of sciatica, such as lumbar degenerative and inflammatory diseases or spinal tumors, which may often lead to a late correct diagnosis. Patients and methodsWe present two cases of sciatic nerve schwannomas that were recently treated at our Institution, and we review the pertinent English literature on this topic over the last 15 years, yielding twenty three cases to analyze. ResultsEven if sciatic nerve schwannomas are a rare occurrence, a thorough clinical and radiological evaluation of the sciatic nerve should be considered whenever a sciatic pain is not otherwise explained. A positive Tinel sign and a palpable mass along the course of the sciatic nerve may be strong clues to achieve the diagnosis. Combined morphological and advanced functional MRI imaging may help to differentiate benign from malignant peripheral nerve sheath tumors, avoiding unnecessary preoperative biopsy. ConclusionsA standard microsurgical technique guided by ultrasound and neurophysiologic monitoring, allows in most of the cases a safe removal of the tumor and very satisfactory post-operative results for the patients.

Endoscopic Transforaminal Discectomy Vs. Far Lateral Discectomy for Extraforaminal Disc Protrusions: Our Experience

Background: Extraforaminal disc herniations are challenging occurrences, requiring a more disruptive approach in terms of bony removal and muscles dissection. We compared outcomes and intraoperative findings between endoscopic transforaminal and far lateral discectomy in the treatment of extraforaminal disc protrusions Methods: We prospectively collected 38 patients who underwent surgery for lumbar extraforaminal disc prolapse, from January 2014 to December 2018. Twenty patients underwent far lateral microsurgical discectomy, whereas eighteen a percutaneous transforaminal endoscopic discectomy. Patients were randomly assigned to a treatment group and were followed-up at intervals of 3, 6, and 16 months. No patients were lost at follow-up. Data were collected on leg pain and disability degree, preoperatively and at follow-up visits, along with demographic data, operative time, amount of intraoperative blood loss, and any postoperative surgical adverse events. Eventually, data analyzed and compared between the two groups. Results: Mean operative time was significantly shorter for endoscopically treated patients compared to patients who underwent microdiscectomy (59.4 vs. 98 minutes, p-value < 0.001). Also, intraoperative blood loss was almost negligible (< 50 ml) for all endoscopically treated patients. There were no differences in terms of postoperative outcomes between patients treated with standard microsurgical techniques and patient who underwent endoscopic transforaminal discectomy at 3, 6, and 16 months of follow-up. Conclusions: transforaminal endoscopic discectomy is a feasible and safe procedure for the treatment of extraforaminal lumbar disc herniation. Our series highlighted the utility and feasibility of the technique, showing similar results to far lateral microsurgical technique.

Comparative evaluation of percutaneous endoscopic and microsurgical lumbar discectomy

The results of percutaneous endoscopic and microsurgical discectomy have been compared. It was established that the operative intervention time, bed-day medians and disability period were significantly shorter (p0,001) in the percutaneous endoscopy group. The average effective dose of radiation exposure for a patient during transforaminal endoscopy was 4,4 mSv, for interlaminar endoscopic techniques and microsurgery - 0,8 mSv. The proportions of complications and repeated operations in both groups were comparable. The risk of recurrence was 10% for the endoscopic group, 4,8% for the microsurgical group. Significant differences in terms of local and radicular pain, quality of life and the physical component of health have not been established. The mental component of health was the best in the endoscopic group. Good and excellent results on the MacNab treatment satisfaction scale in the endoscopy group were observed in 78,2% of cases, after microdiscectomy - in84,9%. Lower invasiveness of percutaneous endoscopy affected the reduction in the period of hospitalization and disability. The effectiveness of percutaneous endoscopic discectomy methods was comparable to standard microsurgical techniques. A statistically insignificant increase in the risk of hernia recurrence after percutaneous endoscopic discectomy was noted. Infectious complications were not typical for percutaneous endoscopic discectomy. Differences in the frequency of complications and reoperations between percutaneous endoscopic and microsurgical lumbar discectomy are also not confirmed.

Efficacy and Outcomes of Posterior Inferior Cerebellar Artery (PICA) Bypass for Proximal PICA and Vertebral Artery-PICA Aneurysms: A Case Series.

Nonsaccular vertebral artery (VA) and posterior inferior cerebellar artery (PICA) aneurysms have high morbidity and mortality rates and are difficult to treat using standard microsurgical or endovascular techniques. Definitive revascularization can require clip trapping and/or vessel sacrifice, with PICA bypass. The published surgical experience with these approaches is limited. We herein review our recent surgical experience with PICA revascularization for complex PICA and VA/PICA aneurysms. To determine the efficacy and outcomes of PICA bypass for revascularization of nonsaccular PICA and VA/PICA aneurysms. Retrospective analysis of an institutional review board-approved, prospective database was performed to identify patients with PICA and VA/PICA aneurysms treated with PICA bypass at a single institution. Demographic information, aneurysm characteristics, temporary clip time, and neurological outcomes were recorded. Ten cases of PICA revascularization were performed for both ruptured (n=8) and unruptured (n=2) nonsaccular proximal PICA or VA/PICA aneurysms. Seven cases were performed without vessel grafts; 3 cases required harvest of the descending branch of the lateral femoral circumflex artery. Mean temporary clip time was 38 min (range 27-50 min). Good outcomes (Glasgow Outcomes Scale score of 5) were achieved in 70% (n=7) of patients at time of discharge; the remaining patients had a Glasgow Outcomes Scale of 3. Two bypass-related complications occurred in this series; a hematoma at the graft harvest site requiring evacuation, and severe bypass graft spasm requiring multiple endovascular treatments. PICA bypass can be a safe, effective, and highly customizable tool for the revascularization of patients with nonsaccular proximal PICA and VA/PICA aneurysms.

Endoscopically Assisted Targeted Keyhole Retrosigmoid Approaches for Microvascular Decompression: Quantitative Anatomic Study

We describe and quantitatively assess minimally invasive keyhole retrosigmoid approaches targeted to the upper, middle, and lower cranial nerve (CN) complexes of the cerebellopontine angle (CPA). Anatomic dissections were performed on 10 sides of 5 fixed, silicone-injected cadaver heads. Surgical views through various trajectories were assessed in endoscopic videos and 3-dimensional (3D) interactive virtual reality microscope views. Surgical freedom and angles of attack to the proximal and distal areas of CN complexes of the CPA were compared among upper and lower keyholes and conventional retrosigmoid craniotomy using neuronavigation. Compared with keyholes, the conventional approach had superior surgical freedom to most areas except for the distal CN V, the root of CN VII, and the root of CN IX, where differences were not significant. The conventional retrosigmoid approach provided a larger horizontal angle of attack than either the upper or lower keyholes for all selected areas; however, the vertical angles of attack were not different. Splitting the petrosal fissure resulted in a significant increase in the vertical angle of attack to the root zones of CNs V and VII but not to the distal areas of these nerves or CN IX. Illustrative cases of endoscope-assisted keyhole retrosigmoid approaches for the treatment of trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia are presented. Targeted keyhole retrosigmoid approaches require detailed understanding of the 3D anatomy of the CPA to create appropriate locations of corridors, including skin incisions and keyholes. Endoscope assistance complements the standard microsurgical technique by maximizing the visualization and identification of the delicate neurovascular structures.

Endoscopy in Temporal Lobe Glioma and Metastasis Resection: Is There a Role?

Surgical access to the temporal lobe is complex with many eloquent white fiber tracts, requiring careful preoperative surgical planning. Many microsurgical approaches to the temporal lobes are described, each with their own disadvantages. The adoption of the endoscope in neurosurgery has increased the options available when treating these difficult access tumors. We present our experience of a novel, minimally invasive, endoscopic approach to resect temporal lobe tumors. All patients undergoing endoscopic temporal lobe tumor resection between December 1, 2011 and December 1, 2017, with a single surgeon, were included. Tumors were resected through a minicraniotomy using a high-definition rigid endoscope with a 0- and 30-degree viewing angle. Bimanual resection was performed using standard microsurgical technique. There were 45 patients (22 men and 23 women) with a mean age of 53 years. There were 23 (51%) glioblastoma multiforme, 11 (24%) metastases, 7 (16%) astrocytoma, 3 (7%) anaplastic astrocytoma, and 1 (2%) World Health Organization grade I glioneuronal tumor. In 82.2% of cases (37/45), >95% resection was achieved and 42.2% (19/45) of patients achieving gross total resection. The endoscope has a role in temporallobe intraparenchymal tumor surgery, especiallyin3illustrative scenarios: 1) medial temporal, parahippocampal-gyruslow-grade nonenhancing gliomas, 2) subcortical high-gradeglioma and metastases medial to the sagittal stratum, and 3) recurrent gliomas with cystic resection cavity. The endoscope offers a safe and useful adjunct to the surgeons' armamentarium in brain tumor surgery. A minimally invasive approach also reduces surgical morbidity and length of stay.

Walk the Line. The Surgical Highways to the Craniovertebral Junction in Endoscopic Approaches: A Historical Perspective.

We compiled a comprehensive literature review on the anatomic and clinical results of endoscopic approaches to the craniocervical junction (CVJ) to better contribute to identify the best strategy. An updated literature review was performed in the PubMed, OVID, and Google Scholar medical databases, using the terms "Craniovertebral junction," "Transoral approach," "Transnasal approach," "Transcervical approach," "Endoscopic endonasal approach," "Endoscopic transoral approach," "Endoscopic transcervical approach." Clinical series, anatomic studies, and comparative studies were reviewed. Pure endonasal and cervical endoscopic approaches still have some disadvantages, including the learning curve and the deeper surgical field. Endoscopically assisted transoral surgery with 30° endoscopes represents an emerging option to standard microsurgical techniques for transoral approaches to the anterior CVJ. This approach should be considered as complementary rather than an alternative to the traditional microsurgical transoral-transpharyngeal approach. The transoral approach with sparing of the soft palate still remains the gold standard compared with the pure transnasal and transcervical approaches because of the wider working channel provided by theformer technique. The transnasal endoscopic approach alone appears to be superior when the CVJlesion exceeds the upper limit of the inferior third of the clivus.

Cystic Cervical Dysraphism: Experience of 12 Cases.

Introduction:Cystic spinal dysraphism of the cervical region is a relatively rare entity, which is more frequently associated with congenital anomalies such as split cord malformation, Chiari malformation, and corpus callosum agenesis, when compared to their lumbosacral counterpart. In our study, we have highlighted the clinical spectrum, associated anomalies (both neural and extra-neural), and surgical nuances of these.Materials and Methods:This study is a retrospective analysis of 225 patients from June 2010 to April 2017. Twelve patients who were between the age of 1 month and 16 years were included in our study. Average age was 32.6 months, and there were five female patients and seven male patients. All patients underwent neurological and radiological examinations followed by surgical excision of the sac and exploration of the intradural sac using the standard microsurgical technique. Neurological, Orthopedic and urological outcomes were studied in our description.Results:Of the 12 cases, 9 patients (75%) had some associated anomaly. Four of the 12 patients (25%) had split cord malformation, 3 had corpus callosum agenesis, and 5 had Chiari malformation. Patients with cervical spina bifida cystica (SBC) present with less neurologic deficits and greater association with CCA.Conclusion:The management strategy and association with other congenital anomalies separates cervical dysraphism as a different clinical entity rather than just group. These patients rather show favorable outcome with regard to neurologic, orthopedic, and urologic problems as compared to their caudal counterpart. Early surgical intervention even before the onset of symptoms is recommended. A proper radiological and urological evaluation is warranted.

Evaluation of a Nerve Fusion Technique With Polyethylene Glycol in a Delayed Setting After Nerve Injury.

Polyethylene glycol (PEG) has been hypothesized to restore axonal continuity using an invivo rat sciatic nerve injury model when nerve repair occurs within minutes after nerve injury. We hypothesized that PEG could restore axonal continuity when nerve repair was delayed. The left sciatic nerves of female Sprague-Dawley rats were transected and repaired in an end-to-end fashion using standard microsurgical techniques at 3 time points (1, 8, and 24 hours) after injury. Polyethylene glycol was delivered to the neurorrhaphy in the experimental group. Post-repair compound action potentials were immediately recorded after repair. Animals underwent behavioral assessments at 3 days and 1 week after surgery using the sciatic functional index test. The animals were sacrificed at 1 week to obtain axon counts. The PEG-treated nerves had improved compound action potential conduction and animals treated with PEG had improved sciatic function index. Compound action potential conduction was restored in PEG-fused rats when nerves were repaired at 1, 8, and 24 hours. In the control groups, no compound action potential conduction was restored when nerves were repaired. Sciatic functional index was superior in PEG-fused rats at 3 and 7 days after surgery compared with control groups at all 3 time points of nerve repair. Distal motor and sensory axon counts were higher in the PEG-treated rats. Polyethylene glycol fusion is a new adjunct for nerve repair that allows rapid restoration of axonal continuity. It effective when delayed nerve repair is performed. Nerve repair with application of PEG is a potential therapy that may have efficacy in a clinical setting. It is an experimental therapy that needs more investigation as well as clinical trials.

Tubular microdiscectomy: techniques, complication avoidance, and review of the literature.

OBJECTIVE Microendoscopic discectomy is a minimally invasive surgery technique that was initially described in 1997. It allows surgeons to work with 2 hands through a small-diameter, operating table-mounted tubular retractor, and to apply standard microsurgical techniques in which a small skin incision and minimal muscle dissection are used. Whether the surgeon chooses to use an endoscope or a microscope for visualization, the technique uses the same type of retractor and is thus called tubular microdiscectomy. The goal in this study was to review the current literature, examine the level of evidence supporting tubular microdiscectomy, and describe surgical techniques for complication avoidance. METHODS The authors performed a systematic PubMed review using the terms "microdiscectomy trial," "tubular and open microdiscectomy," "microendoscopic open discectomy," and "minimally invasive open microdiscectomy OR microdiskectomy." Of 317 references, 10 manuscripts were included for analysis based on study design, relevance, and appropriate comparison of open to tubular discectomy. RESULTS Similar and very favorable clinical outcomes can be expected from tubular and standard microdiscectomy. Studies have demonstrated equivalent operating times for both procedures, with lower blood loss and shorter hospital stays associated with tubular microdiscectomy. Furthermore, postoperative analgesic usage has been shown to be significantly lower after tubular microdiscectomy. Overall rates of complications are no different for tubular and standard microdiscectomy. CONCLUSIONS Prospective randomized trials have been used to evaluate outcomes of common minimally invasive lumbar spine procedures. For lumbar discectomy, Level I evidence supports equivalently good outcomes for tubular microdiscectomy compared with standard microdiscectomy. Likewise, Level I data indicate similar safety profiles and may indicate lower blood loss for tubular microdiscectomy. Future studies should examine the comparative value of these procedures.

Carotid-Falciform Optic Neuropathy: Microsurgical Treatment.

Several recent reports have implicated vascular ectasia and vessel contact in dysfunction of the visual apparatus. A subset of patients with prechiasmatic visual deterioration have an ectatic internal carotid artery (ICA) that displaces and flattens the optic nerve (ON) rostrally as the ON exits the skull base. We describe a proposed pathophysiologic mechanism and a straightforward surgical technique for dealing with this problem. Via an ipsilateral pterional craniotomy, the bony roof of the optic canal is removed. The falciform ligament is opened in parallel to the ON. Adhesions between the ICA and ON are then dissected, and a Teflon pledget is placed between the ICA and ON to complete the decompression. Patients both in the literature and in this series experienced an improvement in their vision postoperatively. We propose that 3 mechanisms contribute to this caroticofalciform optic neuropathy: 1)mass effect from ICA ectasia, 2) ON irritation from vessel pulsatility, and 3) indirect compression by the falciform ligament from above. This disease process can be treated safely using standard microsurgical techniques with excellent outcomes.