Comparative Analysis on Vestibular Schwannoma Surgery with and without Intraoperative Fluorescein Sodium Enhancement.

BACKGROUND: Vestibular schwannoma (VS), also known as acoustic neuroma, is a benign, well-encapsulated, and slow-growing tumor that originates from Schwann cells, which form the myelin sheath around the vestibulocochlear nerve (VIII cranial nerve). The surgical treatment of this condition presents a challenging task for surgeons, as the tumor's location and size make it difficult to remove without causing damage to the surrounding structures. In recent years, fluorescein sodium (FS) has been proposed as a tool to enhance surgical outcomes in VS surgery. This essay will provide an analytical comparison of the use of FS in VS surgery, evaluating its benefits and limitations and comparing surgical outcomes with and without FS-assisted surgery. METHODS: In a retrospective study conducted at San Filippo Neri Hospital, we examined VS cases that were operated on between January 2017 and December 2023. The patients were divided into two groups: group A, which consisted of patients who underwent surgery without the use of FS until January 2020 (102 cases), and group B, which included patients who underwent surgery with FS after January 2020 (55 cases). All operations were performed using the retrosigmoid approach, and tumor size was classified according to the Koos, et al. classification system. The extent of surgical removal was evaluated using both the intraoperative surgeon's opinion and postoperative MRI imaging. Preoperatively and postoperatively, facial nerve function and hearing were assessed. In group B, FS was used to assist the surgical procedures, which were performed using a surgical microscope equipped with an integrated fluorescein filter. Postoperative clinical and MRI controls were performed at six months and annually, with no patients lost to follow-up. RESULTS: This study investigated the impact of intraoperative fluorescein exposure on tumor resection and clinical outcomes in patients with VS. The study found a statistically significant difference in the tumor resection rates between patients who received fluorescein intraoperatively (p = 0.037). Further analyses using the Koos classification system revealed a significant effect of fluorescein exposure, particularly in the Koos 3 subgroup (p = 0.001). Notably, no significant differences were observed in hearing loss or facial nerve function between the two groups. A Spearman correlation analysis revealed a positive correlation between tumor size and Koos, age, and size, but no significant correlation was found between facial nerve function tests. CONCLUSIONS: FS-assisted surgery for VS may potentially enhance tumor resection, allowing for more comprehensive tumor removal.

The "state of the art" of intraoperative neurophysiological monitoring: An Italian neurosurgical survey.

Introduction: Intraoperative Neurophysiological Monitoring (IOM) is widely used in neurosurgery but specific guidelines are lacking. Therefore, we can assume differences in IOM application between Neurosurgical centers. Research question: The section of Functional Neurosurgery of the Italian Society of Neurosurgery realized a survey aiming to obtain general data on the current practice of IOM in Italy. Materials and methods: A 22-item questionnaire was designed focusing on: volume procedures, indications, awake surgery, experience, organization and equipe. The questionnaire has been sent to Italian Neurosurgery centers. Results: A total of 54 centers completed the survey. The annual volume of surgeries range from 300 to 2000, and IOM is used in 10-20% of the procedures. In 46% of the cases is a neurologist or a neurophysiologist who performs IOM. For supra-tentorial pathology, almost all perform MEPs (94%) SSEPs (89%), direct cortical stimulation (85%). All centers perform IOM in spinal surgery and 95% in posterior fossa surgery. Among the 50% that perform peripheral nerve surgery, all use IOM. Awake surgery is performed by 70% of centers. The neurosurgeon is the only responsible for IOM in 35% of centers. In 83% of cases IOM implementation is adequate to the request. Discussion and conclusions: The Italian Neurosurgical centers perform IOM with high level of specialization, but differences exist in organization, techniques, and expertise. Our survey provides a snapshot of the state of the art in Italy and it could be a starting point to implement a consensus on the practice of IOM.

Posterior cranial fossa meningiomas: Comparison of results between patients older and younger than 70 years.

Introduction: Surgical strategy for meningioma resection in the elderly is controversial: diverse studies in the literature have pointed at the age as a negative prognostic factor in terms of postoperative results. Research question: The aim of this study is to compare surgical outcomes after resection of posterior fossa meningiomas in <70 and ≥ 70 years-old age groups. Material and methods: We reviewed 72 patients affected by posterior fossa meningiomas who underwent surgical treatment at San Filippo Neri Hospital, Rome, Italy between September 2010 and December 2022. We analyzed data regarding tumor size, clinical presentation, extent of resection and complication/mortality. Results: The groups consisted of 52 (72,2%) young and 20 (27,8%) elderly patients. Gross total resection rate was significantly higher among youngsters (p = 0,013), mainly for planned subtotal removal in older patients. At 3-month follow-up, clinical improvement was seen in 19 (36,5%) young and 7 (35,0%) elderly patients, which raised at last follow-up, being 84,6% (44) and 80,0% (16), respectively (p = 0,406). Two cases of progression/recurrence among the elderly and 1 among youngsters were observed; one case of mortality among the elderly was reported. Discussion and conclusions: Safety data regarding postoperative complications and mortality in our series seem to confirm that there is no significant difference between older and younger patients, as long as older patients are carefully selected. Therefore, if surgery is proposed, it should be radical if gross total resection could be safely attempted.

Utility of sodium fluorescein in recurrent cervical vagus schwannoma surgery.

Background: Cervical schwannoma is a rare neoplasm that usually occurs like a nondolent lateral neck mass but when growing and symptomatic requires radical excision. Sodium fluorescein (SF) is a dye that is uptake by schwannomas, which makes it amenable for its use in the resection of difficult or recurrent cases. Methods: We describe the case of a patient presenting with a recurrence of a vagus nerve schwannoma in the cervical region and the step-by-step technique for its complete microsurgical exeresis helped by the use of SF dye. Results: We achieved a complete microsurgical exeresis, despite the presence of exuberant perilesional fibrosis, by exploiting the ability of SF to stain the schwannoma and nearby tissues. That happens due to altered vascular permeability, allowing us to better differentiate the lesion boundaries and reactive scar tissue under microscope visualization (YELLOW 560 nm filter). Conclusion: Recurrent cervical schwannoma might represent a surgical challenge due to its relation to the nerve, main cervical vessels, and the scar tissue encompassing the lesion. Although SF can cross both blood-brain and blood-tumor barriers, the impregnation of neoplastic tissue is still greater than that of nonneoplastic peripheric tissues. Such behavior may facilitate a safer removal of this kind of lesion while respecting contiguous anatomical structures.

Clinical and anatomical analysis of the epileptogenic spread patterns in focal cortical dysplasia patients.

Background: Focal cortical dysplasia (FCD) is one of the main causes of intractable epilepsy, which is amendable by surgery. During the surgical management of FCD, the understanding of its epileptogenic foci, interconnections, and spreading pathways is crucial for attaining a good postoperative seizure free outcome. Methods: We retrospectively evaluated 54 FCD patients operated in Federal Center of Neurosurgery, Tyumen, Russia. The electroencephalogram findings were correlated to the involved brain anatomical areas. Subsequently, we analyzed the main white matter tracts implicated during the epileptogenic spreading in some representative cases. We prepared 10 human hemispheres using Klinger's method and dissected them through the fiber dissection technique. Results: The clinical results were displayed and the main white matter tracts implicated in the seizure spread were described in 10 patients. Respective FCD foci, interconnections, and ectopic epileptogenic areas in each patient were discussed. Conclusion: A strong understanding of the main implicated tracts in epileptogenic spread in FCD patient remains cardinal for neurosurgeons dealing with epilepsy. To achieve meaningful seizure freedom, despite the focal lesion resection, the interconnections and tracts should be understood and somehow disconnected to stop the spreading.

Removal of grade IV vestibular schwannomas by retrosigmoid approach: results of a cumulative series of two European centers.

INTRODUCTION: The aim of our study was to study the association between end-of-surgery facial nerve stimulation threshold and extent of tumor resection in case of grade IV vestibular schwannomas. MATERIALS AND METHODS: Grade IV VSs represent a surgical challenge as a risk/benefit ratio must be considered in balancing a satisfactory extent of resection against a good postoperative functional outcome. We reviewed a cumulative series of 57 patients with large/giant VSs who were operated on by retrosigmoid approach in the period from 2008 to 2018 in two European centers, namely San Filippo Neri Hospital, Rome, Italy and Masaryk Hospital, Usti nad Labem, Czech Republic. Extent of resection, intraoperative direct electrical stimulation threshold of facial nerve and postoperative facial outcome were examined. RESULTS: Total or near-total resection was accomplished in 40 (75.5%) cases. Two groups were compared: total or near-total resection (T + NT) and subtotal resection (ST); the end-of-surgery facial nerve stimulation threshold significantly differed (T + NT: 0.24 mA, ST: 0.44 mA, p = 0.036). A critical cutoff was found at 0.2mA; values similar or inferior to this correctly predicted total or near-total resection in 86.7% of cases. Thirty (56.6%) patients had a normal postoperative facial outcome (HB1). Among the 40 patients in T + NT group, 32 (80%) retained an acceptable facial function (HB1-2). CONCLUSIONS: Lower facial nerve stimulation thresholds positively predict a broader extent of resection and total or -near total resection should be accomplished in such cases. Judicious (subtotal) resection is preferred if threshold values increase while dissecting firmly adherent tumors.

Microsurgery of Koos I-II vestibular schwannomas: a case series of 100 consecutive patients.

BACKGROUND: Treatment of small vestibular schwannomas (VS) depends on size, growth pattern, age, symptoms, co-morbidities. Watchful waiting, stereotactic radiosurgery and microsurgery are three valid options of treatment. METHODS: We reviewed clinical sheets, surgical data and results of 100 consecutive patients with Koos Grade I-II VS, operated at our department via a retrosigmoid microsurgical approach between September 2010 and July 2021. Extent of resection was assessed as total, near-total or subtotal. The course of facial nerve (FN) around the tumor was classified as anterior (A), anterior-inferior (AI), anterior-superior (AS) and dorsal (D). FN function was assessed according to House-Brackmann (HB) Scale and hearing level according to AAO-HNS Classification. RESULTS: Mean tumor size was 1.52 cm. FN course was mainly AS (46.0%) in the overall cohort; in Koos I VS, FN was AS in 83.3%. Postoperative FN function was HB I in 97% and HB II in 3% of cases. Hearing preservation (AAO-HNS class A-B) was possible in 63.2% of procedures. Total/near-total removal was achieved in 98%. Postoperative mortality was zero. Transient complications were observed in 8% of patients; permanent complications never occurred. Tumor remnant progression was observed in one case, 5 years after subtotal removal. CONCLUSIONS: Microsurgery represents a valid option for management of VS, including Koos I-II grades, with an acceptable complication rate. In particular, in small VS long-term FN facial outcome, HP and total/near-total removal rate are favorable.

Diluted intracisternal papaverine for microvascular protection of cranial nerves during vestibular schwannoma and cerebello-pontine angle surgery. Commentary and review of the literature.

Vasospasm after resection of skull base tumors is a rare complication that often produces relevant ischemic sequelae. This review of the literature reports a number of published experiences that can help determine the potential causes of vasospasm after cerebello-pontine angle (CPA) tumor and -in particular-vestibular schwannoma (VS) resection, the ways to prevent it, and the methods to obtain the correct diagnosis. The cause appears to be multifactorial and the surgical approach may contribute to the pathogenesis of vasospasm. Neurosurgeons must pay attention to detect possible vasospasm at an early stage of cerebello-pontine. Cerebral blood flow measurement and transcranial Doppler are useful monitoring tools. Intra-operative prevention of vasospasm during CPA tumor resection with papaverine hydrochloride (PPV) seems to play a relevant role. In particular, PPV is a direct-acting vasodilator used to manage vasospasm during various neurosurgical operations. There is large uncertainty about intracisternal PPV dose-related efficacy and side effects. Dilution of PPV in saline prior to application is recommended to avoid complications. In our experience, in line with the literature, we use a pure PPV without excipients 60 mg/2 ml diluted in 20 cc of 0,9% saline solution (0,3%) to prevent Hearing Loss during Posterior Fossa Microvascular Decompression for Typical Trigeminal Neuralgia and other cranial nerves potentially involved during VS and other CPA tumor resection. The aim of this commentary is to analyze and discuss the role of diluted intracisternal PPV for microvascular protection of cranial nerves during CPA tumor surgery.

Usefulness of Intraoperative ultrasound for cortical dysplasia type I treatment - A single-center experience.

Background: Focal cortical dysplasias (FCD) cause a subgroup of malformations of cortical development that has been closely linked to cause drug intractable epilepsy. Attaining adequate and safe resection of the dysplastic lesion has proved to be a viable option to archive meaningful seizure control. Of the three types of FCD (types I, II, and III), type I has the least detectable architectural and radiological abnormalities. This makes it challenging (preoperatively and intraoperatively) to achieve adequate resection. Intraoperatively, ultrasound navigation has proven an effective tool during the resection of these lesions. We evaluate our institutional experience in surgical management of FCD type I using intraoperative ultrasound (IoUS). Methods: Our work is a retrospective and descriptive study, where we analyzed patients diagnosed with refractory epilepsy who underwent IoUS-guided epileptogenic tissue resection. The surgical cases analyzed were from January 2015 to June 2020 at the Federal Center of Neurosurgery, Tyumen, only patients with histological confirmation of postoperative CDF type I were included in the study. Results: Of the 11 patients with histologically diagnosed FCD type I, 81.8% of the patients postoperatively had a significant reduction in seizure frequency (Engel outcome I-II). Conclusion: IoUS is a critical tool for detecting and delineating FCD type I lesions, which is necessary for effective post-epilepsy surgery results.

Hypervascularized Large Vestibular Schwannomas: Single-Center Experience in a Series of Forty Cases.

Background: Vestibular schwannomas (VS) are usually hypovascularized benign tumors. Large VS (Koos grade IV) with unusual vascular architecture are defined as hypervascular (HVVS); the excessive bleeding during microsurgery has a negative impact on results. Methods: Forty consecutive patients were operated on for HVVS (group A). A tendency to bleed and adherence of capsule to nervous structures were evaluated by reviewing intraoperative video records. The cisternal facial nerve (FN) position was reported. Microsurgical removal was classified as total, near-total, subtotal, or partial and the MIB-1 index was evaluated in all. FN results were classified according to the House-Brackmann scale. Results: Results of Group A were compared with those of 45 patients operated on for large low-bleeding VS (group B). Mean tumor diameter was 3.81 cm in group A and 3.58 cm in group B; the mean age was 42.4 and 56.3 years, respectively. The mean American Society of Anesthesiologists Physical Status Scale class of group A was 1.67 versus 2.31 of group B (P < 0.01). Total or near-total resection was accomplished in 76.5% of group A versus 73.3% of group B. Tight capsule adhesion was observed in 67.5% of group A versus 57.8% of group B. Mean MIB-1 was 1.25% and 1.08%, respectively.FN anatomic preservation was possible in 84.6% of group A versus 95.5% of group B; 67.5% of group A had HB grade I or II FN outcome versus 93.3% of group B (P < 0.001). In group A, 8 patients (20.0%) experienced transient postoperative complications versus 4.4% of group B. Recurrence/regrowth was observed in 4 patients in group A versus 1 in group B. Conclusions: Intraoperative video for classification of HVVS was used. Microsurgery of large HVVS was associated with higher (usually transient) complications and recurrence/regrowth rates and poorer FN outcome, especially in patients with tight capsule adhesion.

Surgical management of spinal schwannomas arising from the first and second cervical roots: Results of a cumulative case series.

Objective: Schwannomas of the first and second nerve roots are rare neurosurgical entities, harboring specific surgical features that make surgical resection particularly challenging and deserve specifics dissertations. This study is a retrospectively analysis of 14 patients operated in two different neurosurgical centers: the San Filippo Neri Hospital of Rome and the Federal Centre of Neurosurgery of Tjumen. Materials and Methods: In the last 6 years, 14 patients underwent neurosurgical resection of high cervical (C1-C2) schwannomas, in two different neurosurgical centers. Patients data regarding clinical presentation, radiological findings, and surgical results were retrospectively analyzed. Results: The mean age was 50 years (range 13-74), the follow-up mean duration was 30 ± 8.5 (range 24-72 months), and there was no significant differences among different tumor locations (intradural, extradural, and dumbbell). Surgical results were excellent: gross total resection was achieved in all cases and there were no intraoperative complications or postoperative mortality. All patients presented postoperative clinical improvement except one who remained stable. Karnofsky performance status, at the last follow-up, confirmed a global clinical improvement. No vertebral artery (VA) injury neither spinal instability occurred; nerve root sacrifice was reported in one case. Conclusions: Neurosurgical treatment of C1-C2 schwannomas is associated with good outcomes in terms of extent of resection and neurological function. In particular, dumbbell shape and VA involvement do not represent limitations to achieve complete tumor resection and good clinical outcome. In conclusion, microsurgery represents the treatment of choice for C1-C2 schwannomas.

Preoperative vestibular evoked myogenic potentials (VEMPs), caloric test, and pure tone audiometry to identify the vestibular nerve branch of schwannoma origin: preliminary results in a series of 26 cases.

Vestibular schwannoma (VS) is a benign tumor which develops in the internal auditory canal and the cerebellopontine angle, potentially diminishing hearing or balance. Most VS tumors arise from one of two vestibular branches: the superior or inferior vestibular nerve. Determining the specific nerve of origin could improve patient management in terms of preoperative counseling, treatment selection, and surgical decision-making and planning. The aim of this study was to introduce a preoperative testing protocol with high accuracy to determine the nerve branch of origin. The nerve of origin was predicted on the basis of preoperative vestibular evoked myogenic potentials (VEMPs), caloric stimulation test, and pure tone audiometry on 26 recipients. The acquired data were entered into a statistic scoring system developed to allocate the tumor origin. Finally, the nerve of origin was definitively determined intraoperatively. Receiver operating characteristic (ROC) curves analysis of preoperative testing data showed the possibility of predicting the branch of origin. In particular, ROC curve of combined VEMPs absence, nystagmus detectable at caloric stimulation, and PTA < 75 dB HL allowed to obtain high accuracy for inferior vestibular nerve implant of the tumor (area under the curve-AUC = 0.8788, p = 0.012). In 24 of 26 cases, the preoperatively predicted tumor origin was the same as the origin determined during surgery. Preoperative audiological and vestibular evaluation can predict the vestibular tumor branch of origin with high accuracy. Despite the necessity of larger prospective cohort studies, these findings may change preoperative approach, possible functional aspects, and counseling with the patients.

Endoscopic Transnasal Approaches to Petrous Apex.

Endoscopic extended transnasal approaches to the apex of the temporal bone pyramid are rapidly developing and are widely used in our time around the world. Despite this, the problem of choosing an approach remains relevant and open not only between the "open" and "endoscopic transnasal" access groups but also within the latter. In the article, we systematized all endoscopic approaches to the pyramid of the temporal bone and divided them into three large groups: medial, inferior, and superior-in accordance with the anatomical relationship with the internal carotid artery-and also presented their various, modern (later described), modifications that allow you to work more targeted, depending on the nature of the neoplasm and the goals of surgical intervention, which in turn allows you to complete the operation with minimal losses, and improve the quality of life of the patient in the early and late postoperative period. We described the indications and limitations for these accesses and the problems that arise in the way of their implementation, which in turn can theoretically allow us to obtain an algorithm for choosing access, as well as identify growth points.

Application of Intraoperative Ultrasound Navigation in Neurosurgery.

Effective intraoperative image navigation techniques are necessary in modern neurosurgery. In the last decade, intraoperative ultrasonography (iUS), a relatively inexpensive procedure, has gained widespread acceptance. Aim: To document and describe the neurosurgery cases, in which iUS has been employed as the primary navigational tool. This includes a discussion of the advantages that iUS may possess relative to other forms of neuronavigation. Conclusion: The application of iUS as an intraoperative navigation tool during neurosurgery holds great potential as it has been shown, relative to other neuronavigation techniques, to be quick, repeatable, and able to provide real-time results.

Inflammatory Pseudotumor Simulating a Jugular Foramen Meningioma: Case Report, Technical Video, and Literature Review.

Inflammatory pseudotumor (IP) is a nonneoplastic, reactive inflammatory process, of unknown etiology, characterized by a proliferation of connective tissue with an inflammatory infiltrate, most commonly involving the lungs and orbits. Primary intracranial IP is an extremely rare entity often arising from the meningeal structures of the skull base. We reported an extremely rare case of a primary intracranial IP located in the cerebellopontine angle, mimicking a jugular foramen meningioma. We further illustrated our microsurgical technique through a surgical video and performed a review of the pertinent scientific literature. The patient underwent gross total microsurgical resection of the tumor mass through a left retrosigmoid approach. Intraoperative neuromonitoring of the VII-VIII cranial nerve complex and lower cranial nerve was performed, and thulium laser fibers were used as a tool for tumor debulking. Postoperatively, the patient's neurologic symptoms recovered. Histopathologic studies showed dense infiltrate of T- and B-cell lymphocytes and epithelioid granulomas, compatible with the diagnosis of IP. Postoperatively, magnetic resonance imaging scans showed complete tumor resection. The patient underwent a 3-month oral corticosteroid therapy showing no signs of recurrence at the radiologic follow-up. Primary intracranial IPs are rare pathologic entities that can mimic extraaxial tumors and should be taken into consideration as a potential differential diagnosis. Complete microsurgical resection in combination with other treatments (steroids therapy, radiotherapy) is the most common treatment of choice and is associated with good outcomes and low rates of recurrence.

Microsurgical treatment of symptomatic vestibular schwannomas in patients under 40: different results before and after age of 30.

In 10-15% of cases of vestibular schwannoma (VS), age at diagnosis is 40 years or less. Little is known about the differences in natural history, surgical findings, and postoperative outcomes of such younger patients as compared to those of greater age. To analyze clinical and surgical and imaging data of a consecutive series of n = 50 patients with unilateral sporadic VS, aged 40 years or younger - separated in a very young group (15-30 years) and a moderately young group (31-40 years). Retrospective case series. Fifty consecutive patients under 40 years of age underwent microsurgical resection of unilateral sporadic VS via the retrosigmoid approach. The study cohort was subdivided into two groups according to the age range: group A, age range 15-30 years (n = 23 patients), and group B, age range 31-40 years (n = 27 patients). The adherence of VS capsule to surrounding nervous structures and the tendency of the tumors to bleed were evaluated by reviewing video records; the course of the FN in relation to the tumor's surface was assessed in each case. Microsurgical removal of tumor was classified as total (T), near total (residual tumor volume < 5%), subtotal (residual tumor volume 5-10%), or partial (residual tumor volume > 10%). Mean tumor size of entire cohort was 2.53 (range: 0.6-5.8) cm: 2.84 cm in group A and 2.36 cm in group B (p = NS). Facial nerve course and position within the cerebellopontine angle did not differ significantly between the two groups. At 6-month follow-up, FN functional outcome was HBI-II in 69.5% in group A, versus 96.3% in group B (p < .001). Hearing preservation was achieved in 60.0% of patients of group A and in 58.3% of group B (p = NS). Total and near-total resection was feasible in 95.6% of cases of group A and in 88.9% of group B (p = NS). Tumor capsule was tightly adherent to nervous structures in 69.6% patients of group A and in 22.2% of group B (p < .05). Significant bleeding was encountered in 56.5% of group A tumors, and in 29.6% of group B tumors (p < .01). Microsurgery of VS in patients aged 40 or less is associated with good functional results, and with high rates of total and near total tumor removal. Patients < 30 years of age have more adherent tumor capsules. Furthermore, their tumors exhibit a tendency to larger sizes, to hypervascularization, to profuse intraoperative bleeding and they present worse long-term functional FN results when compared to patients in their fourth decade of life. Our limited experience seems to suggest that a near total resection in very young VS patients with large tumors should be preferred in adherent and hypervascularized cases, in order to maximize resection and preserve function.

Single-Level Cervical Arthroplasty with a Keel-less Prosthesis: Results in a Series of 35 Patients Operated on for Soft Disk Herniation with a Minimum of 3 Years of Follow-Up.

BACKGROUND: Cervical arthroplasty with artificial cervical disks has gained popularity as an alternative to anterior discectomy and fusion. The main advantages of disk arthroplasty include maintenance of the range of movement, restitution of disk height and spinal alignment, and reduction of adjacent segment degeneration (ASD). In this article, we aimed to assess the outcomes of the use of a keel-less prosthesis. MATERIAL AND METHODS: We included all the patients who underwent single-level cervical arthroplasties with the Discocerv Cervidisc Evolution for "soft" disk herniation. Clinical assessment included Neck Disability Index (NDI) and visual analog scale (VAS) for neck and arm pain. Radiologic studies investigated the occurrence of ASD and system failure or subsidence. The reoperation rate was also recorded. RESULTS: The study included 35 patients (14 men and 21 women; mean age: 42.5 years; mean follow-up: 57.8 months). There was a significant decrease in VAS neck and VAS arm scores, which went from 7.2 and 6.9 preoperatively to 2.2 and 1.7 postoperatively, 2.2 and 1.6 at 6 months, 2.0 and 1.8 at 1 year, and 2.1 and 1.3 at the last follow-up, respectively. The mean NDI score was 58.0 preoperatively, 19.4 postoperatively, 17.0 at 6 months, 16.1 at 1 year, and 16.2 at the last follow-up. Radiologic studies revealed a preserved range of motion in 33 of 35 patients. No ASD occurred and no reoperation was required. CONCLUSIONS: Cervical disk arthroplasty with a keel-less prosthesis can be a safe and effective alternative to fusion for degenerative disk disease in selected patients, with a possible reduction of ASD.