Salvage Surgery for Symptomatic Recurrence of Retro-Odontoid Pseudotumor after a C1 Laminectomy.

We provide the first report of successful salvage surgery for a post-C1 laminectomy symptomatic recurrence of a retro-odontoid pseudotumor (ROP) that caused myelopathy. The 72-year-old Japanese woman presented with an ROP causing symptomatic cervical myelopathy. With ultrasonography support, we performed the enucleation of the ROP via a transdural approach and fusion surgery for the recurrence of the mass. At the final observation 2-year post-surgery, MRI demonstrated the mass's regression and spinal cord decompression, and the patient's symptoms had improved. Our strategy is an effective option for a symptomatic recurrence of ROP.

Occipitocervical fusion complicated with cerebellar abscess: a case report.

BACKGROUND: Occipitocervical (OC) fusion is indicated for OC instability and other conditions. Surgical complications include infection, malunion, and instrument failure. CASE PRESENTATION: We described a patient who underwent OC fusion and subsequently developed complication of cerebellar abscess and obstructive hydrocephalus. A 63-year-old male patient had been suffering from long-term neck pain and limb numbness and weakness. Cervical spine examination revealed tight stenosis at C1 level and instability in the C1-C2 joints. A C1 laminectomy with OC fusion was performed, and the patient was discharged. Unfortunately, a few days later, he went to the emergency department and complained of persistent dizziness, vomiting, and unsteady gait. Computed tomography (CT) and magnetic resonance imaging (MRI) images revealed a suspicious cerebellar abscess formation and hydrocephalus. Furthermore, CT images indicated that the left screw was loose, and the diameter of the right screw hole was much larger than the size of the screw. Besides, inappropriate length of the screw penetrated the occipital bone and may cause the disruption of dura mater. The patient underwent external ventricular drainage first, followed by abscess drainage and C1-C2 fixation a few days later. He was discharged without any further neurological deficits or infectious problems. The patient recovered with intact consciousness, full muscle strength, and improved numbness throughout the extremities, with a Nurick grade of 1. A follow-up magnetic resonance imaging at 3 months after surgery revealed near total resolution of the abscess. Inform consent was obtained from this patient. CONCLUSIONS: Carefully conducting the procedure using the most tailored approach is essential to successful surgery, but this rare complication should always be kept in mind.

Dysphagia following C1 laminectomy and posterior atlantoaxial fixation for retro-odontoid pseudotumor: a case report.

Purpose: Although dysphagia is known potential complication of cervical spine surgery, it rarely occurs after a posterior approach. We describe an unusual case of a retro-odontoid pseudotumor that suffered dysphagia following a C1 laminectomy and posterior atlantoaxial fixation.Materials and methods: A 79-year-old man presented with progressive tetraparesis and bladder and bowel dysfunction due to severe compression to cervical cord at C1 from a retro-odontoid pseudotumor. After C1 laminectomy and atlantoaxial fixation, the symptoms improved, but dysphagia and aspiration developed, associated with pharyngeal and esophageal stases on videofluoroscopy.Results and conclusions: Possible explanations for postoperative dysphagia include limitation of cervical spine motion, and cervical cord reperfusion injury in addition to the baseline anterior osteophyte and aging. This is the first case of dysphagia developing after laminectomy and posterior atlantoaxial fixation not involving the occipital bone.

Evaluation of the Bone Union Occurring Subsequent to C1-2 Fusion Combined With C1 Laminectomy for the Surgical Treatment of Retro-Odontoid Pseudotumor.

Introduction Surgical treatments for retro-odontoid pseudotumors (ROPs) include C1 laminectomies and C1-2 and occipitocervical (OC) fusions. When a C1 laminectomy is combined with a C1-2 fusion, concerns arise regarding an increased risk of pseudarthrosis due to decreased bone grafting space. Extension of the fusion area to the OC region may be considered to ensure an adequate bone graft bed. However, this procedure is associated with a risk of complications. Thus, in this study, we investigated the bone fusion and clinical outcomes of C1-2 fusion combined with a C1 laminectomy. Methods Between January 2017 and December 2022, seven patients with ROPs who had undergone C1-2 fusion combined with a C1 laminectomy were included in the study. All patients were followed up for >1 year. Bone fusion was evaluated by computed tomography (CT) at one year postoperatively, while implant failure was assessed by radiography at the final follow-up. Clinical evaluations included preoperative and one-year postoperative Japanese Orthopaedic Association (JOA) scores and recovery rates. Results This study included five male and two female patients, with an average age of 71.9 years. The average follow-up duration was 3.3 years. The primary anchor choices included the C1 lateral mass screw and the C2 pedicle screw. In one case, the transarticular screw was utilized unilaterally, and in another case, a lamina screw was utilized unilaterally. One year postoperatively, CT revealed bone fusion in three of the seven patients. Fusion occurred at the lateral and median atlantoaxial joints in two cases and one case, respectively. Screw loosening was observed in one case. None of the patients required reoperations. The average JOA recovery rate was 34.6%. Conclusion This surgical technique is useful for stabilizing and decompressing the C1-2 region while preserving mobility at the OC joint. However, further long-term follow-up studies are required.

Modified Atlantoaxial Arthrodesis Technique for Atlantoaxial Instability via Intraarticular Autografting Using Structural Iliac Bone: Technical Nuances and Case Series.

OBJECTIVE: The present study described a modified technique of atlantoaxial arthrodesis in patients with atlantoaxial instability (AAI) along with the postoperative clinical and radiological results. METHODS: Five patients underwent this method for their AAI concurrent with C1 arch hypoplasia and/or the development of odontoid pannus causing myelopathy. After thorough exposure of the posterior surface of the C1-2 complex, the bilateral C2 nerve roots were sectioned to allow for easier access to the C1/2 facet joints. To prepare a suitable grafting bed, the C1/2 facet capsule was opened, and then the articular cartilaginous and synovial tissues were thoroughly removed. After being properly fashioned to match the gap between the C1/2 facet joint spaces, the structural bone grafts from the iliac crest were directly inserted into the facet joint spaces. To alleviate cord compression caused by concomitant odontoid pannus and/or hypoplastic C1 arch, C1 laminectomy was necessitated in all cases. Subsequently, posterior screw-rod instrumental fixation was conducted. RESULTS: All 5 patients underwent this procedure successfully. Clinical and radiological follow-up data of all patients indicated favorable relief of clinical symptoms and early rigid C1-2 stability. The sequelae of C2 nerve resection were not remarkable. No other neural or vascular damage associated with this technique was observed. CONCLUSIONS: Modified atlantoaxial arthrodesis via intraarticular autografting using the structural iliac bone combined with posterior instrumentation appears to be an efficient alternative treatment method for AAI patients with concurrent pathologies, even when the C1-2 posterior arches are unavailable for the grafting bed.

Chiari malformation presenting with subarachnoid hemorrhage: a case report.

Chiari malformations (CM) are often diagnosed in childhood and younger adults, with an incidence of only 0.77% in adult populations. Patients with CM may develop syringomyelia and increased intracranial pressure (ICP) due to cerebrospinal fluid (CSF) obstruction and altered fluid dynamics at the cervicomedullary junction. We describe the case of a 65-year-old female presenting with an angionegative subarachnoid hemorrhage (SAH) with concomitant new diagnosis of CM type I with syringomyelia. After ruling out any aneurysm or vascular malformations, she underwent a suboccipital craniectomy for a Chiari decompression with a C1 laminectomy. There were no complications with the surgery and her symptoms improved. This case report highlights the unusual presentation of a CM.

Far-lateral approach without C1 laminectomy for microsurgical treatment of vertebral artery and proximal posterior inferior cerebellar artery aneurysms: Experience from 48 patients.

Background: In the endovascular era, most of vertebral artery (VA) and posterior inferior cerebellar artery (PICA) aneurysms were mainly treated with endovascular procedures. This study aimed to demonstrate the microsurgical treatment via the far-lateral approach without C1 laminectomy and its clinical outcomes. Methods: Forty-eight patients with VA and proximal PICA aneurysms treated by microsurgery through the far-lateral approach without C1 laminectomy, between January 2016 and June 2021, were retrospectively evaluated. Results: Most patients (87.5%) presented with subarachnoid hemorrhage. Grading at presentation was poor in 41.7%. The rates of VA dissecting aneurysms, saccular aneurysms of the VA-PICA junction, and true PICA saccular aneurysms were 54.2, 18.7, and 14.6%, respectively. All aneurysms were located above the lower margin of the foramen magnum. The far-lateral approach without C1 laminectomy was successfully used in all patients without residual aneurysms. Various surgical strategies were applied depending on the characteristics of the aneurysm. Good outcomes 3 months postoperatively were achieved in 77.1% and 89.3% for the overall and good-grade groups, respectively. Conclusions: Microsurgery is a safe and effective treatment of VA and proximal PICA aneurysms. Moreover, the far-lateral approach without C1 laminectomy was adequate and effective for aneurysms located above the lower border of the foramen magnum.

Resolution of a Focal Pruritic Rash Following Neurosurgical Decompression in an Adolescent With Chiari I and Syringomyelia.

BACKGROUND: Chiari I malformation (Chiari I) is defined by the downward displacement of one or both cerebellar tonsils below the foramen magnum of the skull with crowding altering cerebrospinal fluid flow. It can be associated with the development of a fluid-filled cavity within the spinal cord, syringomyelia. Neurological deficits or symptoms can occur at the level of anatomic involvement of syringomyelia. CASE PRESENTATION: A young man presented to dermatology clinic for evaluation of a pruritic rash. Recognizing a unique left "cape-like" distribution of neuropathic itch leading to prurigo nodularis, he was referred for further evaluation by neurology in the local emergency department. After additional history and neurological exam, a magnetic resonance imaging confirmed Chiari I with an associated syringobulbia and a syrinx extending to T10/11 of the spinal cord. Anteriorly the syrinx extended into the left parenchyma of his spinal cord involving the dorsal horn, a lesion explaining his neuropathic itch. The sensation of itch and rash resolved after posterior fossa craniectomy and C1 laminectomy with duraplasty. CONCLUSION: Neuropathic itch, in addition to pain, can be a symptom of Chiari I with syringomyelia. Focal pruritus without an obvious cutaneous trigger should prompt providers to consider a central neurological pathology. While many patients with Chiari I are asymptomatic, the presence of neurological deficits and syringomyelia, are indications for neurosurgical evaluation.

Cervical Myelopathy Caused by Non-Rheumatic Retro-Odontoid Pseudotumor: An Investigation of Underlying Mechanisms and Optimal Surgical Strategy.

STUDY DESIGN: Retrospective case-control study. OBJECTIVE: This study aimed to identify the underlying pathologies of non-rheumatic retro-odontoid pseudotumors (NRPs), which would help establish an appropriate surgical strategy for myelopathy caused by NRP. METHODS: We identified 35 patients with myelopathy caused by NRP who underwent surgery between 2006 and 2017. An age- and sex-matched control group of 70 subjects was selected from patients with degenerative cervical myelopathy. Radiographic risk factors for NRP were compared between cases and controls. We also assessed surgical outcomes following occipital-cervical (O-C) fusion, atlantoaxial (C1-2) fusion, or C1 laminectomy. RESULTS: Patients with NRP had significantly lower C1 sagittal inner diameter, C2-7 range of motion (ROM), C2-7 Cobb angle, and C7 tilt, as well as significantly higher C1-2 ROM, atlantodental interval (ADI), and C1-2 to O-C7 ROM ratio. Multivariate regression analysis revealed that ADI, C2-7 ROM, and C7 tilt were independent risk factors for NRP. Neurological recovery and pseudotumor size reduction were comparable among surgical procedures, whereas post-operative cervical spine function was significantly lower in the O-C fusion group than in the other groups. CONCLUSION: Non-rheumatic retro-odontoid pseudotumor was associated with an increase in ADI, suggesting that spinal arthrodesis surgery is a reasonable strategy for NRP. C1-2 fusion is preferable over O-C fusion because of the high prevalence of ankylosis in the subaxial cervical spine. Given that 29% of patients with NRP have C1 hypoplasia, such cases can be treated by posterior decompression alone. Our study highlights the need to select appropriate surgical procedures based on the underlying pathology in each case.

Percutaneous full endoscopic C1 laminectomy for developmental atlantal stenosis with myelopathy: a case report of three cases and review of the literature.

Background: Developmental atlantal stenosis with myelopathy (DASM) in adults is a rare disease that only sporadic cases have been reported over the years. C1 laminectomy (C1L) is one of the most common operations for its treatment. However, as an open surgery, it has shortcomings such as large trauma and slow postoperative rehabilitation, and minimally invasive spine surgery (MISS) offers alternative treatment options with advantages. MISS instruments expand the technical capabilities of surgeons, which allows safer and more effective therapeutics for difficult and complicated diseases. This case report presents a new minimally invasive approach; percutaneous full endoscopic C1 laminectomy (PFEC1L), for the treatment of DASM, and to consolidate the current literature on the condition to summarize its etiologies, clinical manifestations, diagnostic criteria, surgical management, and prognoses. Case Description: The patient in Case 1 presented with neck pain and numbness and weakness in the limbs. The patient in Case 2 presented with numbness in the extremities and the patient in Case 3 presented with bilateral hand numbness and left lower limb weakness. They were all diagnosed with DASM and underwent PFEC1L treatment to maintain the enlargement and decompression of the atlantal canal, which achieved favorable outcomes without complications during the postoperative follow-up visit. Conclusions: DASM is rare but potentially dangerous. Its diagnosis is made based on clinical manifestations combined with radiological imaging examinations, especially computed tomography (CT) scan and magnetic resonance imaging (MRI). While C1L is the most common surgical method, PFEC1L is a new feasible and safe therapeutic option with comparable good outcomes and the advantage of being minimally-invasive. To our knowledge this is the first report that PFEC1L was applied for DASM treatment.

Evaluation of Dural Parameters at C1 Level in Patients with Chiari 1 Malformation Following Foramen Magnum and C1 Posterior Arch Removal: Introduction of a Novel Concept to Decompress without Affecting Stability.

Background: Chiari 1 malformation has crowding at craniovertebral junction (CVJ), treated by Foramen magnum decompression (FMD) but is associated with high failure rates, which is explained by recently introduced concept of central instability. So, we propose a new concept of relieving this crowding without affecting stability. Objective: To derive a threshold for coring out of internal surface of C1 posterior arch instead of complete laminectomy accompanying FMD. Methods and Material: We prospectively included nine patients with a mean age of 25.33 ± 7.97 years, diagnosed with ACM-1 without AAD, who were operated with FMD and lax duraplasty and C1 laminectomy. The preoperative dural diameter and area covered under the dura at the level of C1 were measured and compared with the postoperative state. Results were analyzed to derive a cut-off threshold which could be drilled from the inner aspect of C1 arch. Results: The postoperative AP diameter of the dura increased statistically significantly from pre-op; however, the AP extension was less than the preoperative diameter with posterior arch included. Likewise, the area spanned by the dura increased statistically significantly from pre-op but was less than the cumulative area of dura with C1 arch included in pre-op. Analyzing all, a mean cut-off of 50.58% was achieved. Conclusion: The authors suggest FMD with partial coring (~50%) of the inner part of arch of C1, instead of full-thickness laminectomy with a wider length of coring as the target, and this will serve the purpose intended, without increasing mobility.

Midline Suboccipital Subtonsillar Approach with C1 Laminectomy for Resection of Foramen Magnum Meningioma: 2-Dimensional Operative Video.

We present a case of a medium-sized foramen magnum meningioma that was resected through a midline suboccipital subtonsillar approach with C1 laminectomy in prone (Concorde) position. The patient is a 77-year-old woman with a 6-month history of intermittent vertigo, moderate gait instability, and slight decline of memory. On magnetic resonance imaging (MRI) an extra-axial intradural lesion was discovered that originated from the right epicondylar region just inferior to the jugular tubercle and occupied the anterolateral aspect of the foramen magnum. There was moderate transposition and compression of the medulla at the level of the cerebellar tonsils. On physical examination the patient was ambulatory independently without motor weakness but exhibited some gait instability. The function of the lower cranial nerves was preserved. A gross-total resection was achieved, histopathology confirmed a WHO grade-I meningothelial meningioma with a low-proliferation index. The patient was discharged home 5 days after surgery, her gait instability improved significantly immediately after surgery and had resolved completely after 2 weeks of inpatient rehabilitation. There was no other neurological deficit. At 3-month follow-up MRI, there was no indication of meningioma residual or recurrence. In summary, the midline suboccipital subtonsillar approach is a powerful tool with limited morbidity in the armamentarium for the microsurgical management of a variety of pathologies residing in the posterior cranial fossa and the craniocervical junction. Oftentimes the space created by the pathology opens up corridors that can be exploited for microsurgical access to avoid more extensive surgical approaches. The link to the video can be found at: https://youtu.be/0uUxs13ze7w .

Biomechanical evaluation of the craniovertebral junction after unilateral joint-sparing condylectomy: implications for the far lateral approach revisited.

OBJECTIVE The far lateral transcondylar approach to the ventral foramen magnum requires partial resection of the occipital condyle. Early biomechanical studies suggest that occipitocervical (OC) fusion should be considered if 50% of the condyle is resected. In clinical practice, however, a joint-sparing condylectomy has often been employed without the need for OC fusion. The biomechanics of the joint-sparing technique have not been reported. Authors of the present study hypothesized that the clinically relevant joint-sparing condylectomy would result in added stability of the craniovertebral junction as compared with earlier reports. METHODS Multidirectional in vitro flexibility tests were performed using a robotic spine-testing system on 7 fresh cadaveric spines to assess the effect of sequential unilateral joint-sparing condylectomy (25%, 50%, 75%, 100%) in comparison with the intact state by using cardinal direction and coupled moments combined with a simulated head weight "follower load." RESULTS The percent change in range of motion following sequential condylectomy as compared with the intact state was 5.2%, 8.1%, 12.0%, and 27.5% in flexion-extension (FE); 8.4%, 14.7%, 39.1%, and 80.2% in lateral bending (LB); and 24.4%, 31.5%, 49.9%, and 141.1% in axial rotation (AR). Only values at 100% condylectomy were statistically significant (p < 0.05). With coupled motions, however, -3.9%, 6.6%, 35.8%, and 142.4% increases in AR+F and 27.3%, 32.7%, 77.5%, and 175.5% increases in AR+E were found. Values for 75% and 100% condyle resection were statistically significant in AR+E. CONCLUSIONS When tested in the traditional cardinal directions, a 50% joint-sparing condylectomy did not significantly increase motion. However, removing 75% of the condyle may necessitate fusion, as a statistically significant increase in motion was found when E was coupled with AR. Clinical correlation is ultimately needed to determine the need for OC fusion.

Spontaneous C1 anterior arch fracture as a postoperative complication of foramen magnum decompression for Chiari malformation type 1.

BACKGROUND: C1 fracture accounts for 2% of all spinal column injuries and 10% of cervical spine fractures, and is most frequently caused by motor vehicle accidents and falls. We present a rare case of C1 anterior arch fracture following standard foramen magnum decompression for Chiari malformation type 1. CASE DESCRIPTION: A 63-year-old man underwent standard foramen magnum decompression (suboccipital craniectomy and C1 laminectomy) under a diagnosis of Chiari malformation type 1 with syringomyelia in June 2009. The postoperative course was uneventful until the patient noticed progressive posterior cervical pain 5 months after the operation. Computed tomography of the upper cervical spine obtained 7 months after the operation revealed left C1 anterior arch fracture. The patient was referred to our hospital at the end of January 2010 and C1-C2 posterior fusion with C1 lateral mass screws and C2 laminar screws was carried out in March 2010. Complete pain relief was achieved immediately after the second operation, and the patient resumed his daily activities. CONCLUSION: Anterior atlas fracture following foramen magnum decompression for Chiari malformation type 1 is very rare, but C1 laminectomy carries the risk of anterior arch fracture. Neurosurgeons should recognize that fracture of the atlas, which commonly results from an axial loading force, can occur in the postoperative period in patients with Chiari malformation.