Assessment of unintended shifts during frame-based stereotactic radiosurgery using cone beam computed tomography image guidance.

PURPOSE: To investigate the frequency, magnitude and possible causes of frame-shifts that may occur between treatment planning and treatment delivery when performing Gamma Knife radiosurgery with rigid frame-based immobilization. METHODS: Differences between computed tomography (CT) framed fiducial stereotactic coordinate reference and cone beam computed tomography stereotactic coordinates after image registration were recorded for 49 frame-based GK radiosurgery cases performed using the Gamma Knife Icon. Parameters recorded include rotational shifts, translational shifts, and the GK-computed Maximum Shot Displacement (MSD) between the two stereotactic coordinate spaces. Other patient-specific parameters were collected and linear regression analysis was performed to evaluate predictors of increased displacement. RESULTS: The median values of rotational shifts were: pitch 0.14°, yaw 0.17°, and roll 0.13°. The median absolute values of translational shifts were: left-right 0.39 mm, anteroposterior 0.14 mm, and superior-inferior 0. 22 mm. The median value of MSD was 0.71 mm. Twelve cases (24.5%) had a MSD of greater than 1.0 mm. Male gender was associated with increased MSD (p = 0.013) and translational shifts (root-mean-squared value, p = 0.017). Cases with large differences between right and left sided pin lengths were also associated with increased MSD (p = 0.011). CONCLUSIONS: The use of CBCT image guidance in frame-based GK radiosurgery allows unintended frame shifts to be identified and corrected. A significant fraction (24.5%) of patients had large enough shifts to result in a MSD of greater than 1.0 mm. Male gender and eccentrically placed frames were associated with increased MSD, and particular care should be taken in these cases.

In NPH, setting valve opening pressure close to lumbar puncture opening pressure decreases overdrainage.

BACKGROUND: The management of normal pressure hydrocephalus (NPH) can be difficult, partly because there are frequent treatment complications such as overdrainage which, when serious, may require surgical intervention. We previously reported a correlation between the difference of lumbar puncture opening pressure minus the valve opening pressure setting (LPOP-VOP) (which we refer to as the delta) and increased rates of overdrainage. This led to a modification in our practice, whereby we now set the VOP equal to, or close to, the LPOP, resulting in lower deltas. OBJECTIVE: In this new study, our aim was to compare the rate of overdrainage in our patients with higher and lower deltas and assess the significance of setting the VOP equal, or close, to the patient's LPOP. METHODS: 1. We reproduced the association between delta and overdrainage. 2. We compared the incidence of overdrainage in those whose VOP was set close to LPOP (low delta) versus those with VOP setting distant from the LPOP (higher delta). 3. We compared symptom improvement in those with a low versus higher delta. RESULTS: We confirmed the relation between high delta and an increased rate of overdrainage, lower rates of overdrainage in those whose VOP was set close to the LPOP (Delta Adjusted Practice), and better improvement of symptoms when the VOP was set closer to the LPOP. CONCLUSION: We propose that the initial VOP should be set as close as possible to the patient's LPOP to decrease overdrainage without compromising symptom improvement.

Surgical treatment of bilateral glossopharyngeal neuralgia.

Glossopharyngeal neuralgia (GPN) is a condition characterised by sudden, severe pain in the distribution of the glossopharyngeal nerve. It can be triggered by talking, yawning, coughing and swallowing. Classically, patients experience a unilateral lancinating and excruciating pain described as electrical shock-like pain in the areas around the ear, tongue, or the mandibular angle. Uncommon manifestations include cardiac arrhythmias and syncope during pain episodes. Surgery is indicated in refractory cases. Bilateral GPN is rare, and definitive surgical treatment for bilateral GPN has not yet been reported. In this case report, a young woman with bilateral GPN who underwent staged surgery bilaterally is described. She did not develop life-threatening cardiac abnormalities postoperatively.

Spinocerebellar ataxia 15: A phenotypic review and expansion.

Spinocerebellar ataxia 15 (SCA15) is a clinically heterogeneous movement disorder characterized by the adult onset of slowly progressive cerebellar ataxia. ITPR1 is the SCA15 causative gene. However, despite numerous reports of genetically-confirmed SCA15, phenotypic uncertainty persists. We reviewed the phenotypes of 60 patients for whom SCA15 was confirmed by the presence of a genetic deletion involving ITPR1. The most prevalent symptoms were gait ataxia (88.3%), dysarthria (75.0%), nystagmus (73.3%), and limb ataxia (71.7%). We also present a novel SCA15 phenotype in a woman with an ITPR1 variant found to have hydrocephalus that improved with ventriculoperitoneal shunting. This is the first reported case of hydrocephalus associated with SCA15. In this review, we analyzed previously reported SCA15 phenotypes and present a novel SCA15 phenotype. We also address important considerations for evaluating patients with complex hereditary movement disorders.

Laryngeal Mask Airway and Valsalva Maneuver During Ophthalmic Surgery: A Case Report.

The use of a supraglottic airway, also called laryngeal mask airway (LMA), is gaining in popularity for delivery of general anesthesia in certain situations and is shown to be safe. Use of infraglottic airways (tracheal tubes) allows for positive pressure ventilation and maneuvers, such as holding continuous positive pressure in the airway to check for pleural and dural leaks. We describe the successful use of the LMA (Teleflex Inc) for general anesthesia, in which continuous positive airway pressure of 15 cm H2O held for 20 seconds allowed the neurosurgeon to identify the site of a cerebrospinal fluid (CSF) leak and successfully repair the leak. A well-seated LMA can be successfully used to produce continuous positive pressure in the airway not exceeding 20 cm H2O for 20 seconds to facilitate surgical identification of CSF leaks.

Mask-based immobilization in Gamma Knife stereotactic radiosurgery.

The Gamma Knife Icon (Elekta AB, Stockholm) is a cobalt-based stereotactic radiosurgery (SRS) unit to support the use of a thermoplastic mask in lieu of a rigid frame, using an onboard cone-beam CT (CBCT) and an intrafraction motion management system (IFMM). We retrospectively reviewed 124 patients treated with Gamma Knife SRS from January 2018 to December 2019 at our institution using a mask-based immobilization system. Patient and treatment characteristics were collected and summarized as well as interfraction shifts and treatment-related outcomes. This dataset includes 124 patients with an associated 358 intracranial tumors. Twenty-four patients presented with primary brain tumors, which included 14 meningiomas and 10 other histologies, with 100 patients having brain metastases. Sixty tumors were post-operative, while 298 were intact. The median dose for primary tumors was 25 Gy in 5 fractions. Median doses to metastases were 20 Gy in 1 fraction, 27 Gy in 3 fractions, and 25 Gy in 5 fractions. Median interfraction CBCT shifts were submillimeter. Median patient follow-up was 6.28 months. 91% of patients with metastases maintained local control. Our early clinical experience has demonstrated limited toxicity profiles and high patient tolerance, which suggests that mask-based Gamma Knife SRS provides a safe alternative option for frameless SRS. Patients with large target volumes where fractionation is preferred or with small target volumes in non-eloquent areas can be considered for this approach. Response rates are encouraging, and continued follow-up is necessary to investigate long-term control and survival.

Results of surgical resection of carotid body tumors: A twenty-year experience.

This study examines whether surgical resection of carotid body tumors (CBTs) is acceptable in light of potential significant neurologic complications. This IRB-approved retrospective study analyzed data from 24 patients undergoing surgical treatment for CBTs between April 1998 and April 2017 at Mayo Clinic (Florida campus only). For patients who underwent multiple CBT resections, only data from the first surgery was used in this analysis. CBT resection occurred in 24 patients with the following demographics: fourteen patients (58.3%) were female, median age was 56.5 years, median BMI was 29. A prior history of neoplasm was found in ten patients (41.7%). A known family history of paraganglioma was present in five patients (20.8%). Two patients were positive for succinate dehydrogenase mutation (8.3%). Multiple paragangliomas were present in seven patients (29.2%). There was nerve sacrifice in three patients (12.5%) during resection. Carotid artery reconstruction and patch angioplasty occurred in one patient (4.2%). Complete resection occurred in 24 patients (100.0%). Postoperatively, one patient (4.2%) suffered stroke. No mortalities occurred within or beyond 30 days of surgery. Persistent cranial nerve injury occurred in two patients (8.3%) with vocal cord paralysis. There was no recurrence of CBT through last follow-up. Five patients (20.8%) were diagnosed with other neoplasms after resection, including basal cell carcinoma, contralateral carotid body tumor, glomus vagale, and glomus jugulare. There was 100% survival at 1 year in patients followed for that time (n = 17). Surgical treatment remains the first-line curative treatment to relieve symptoms and ensure non-recurrence. While acceptable, neurologic complications are significant and therefore detailed preoperative informed consent is mandatory.

Endocrine and Visual Outcomes Following Gross Total Resection and Subtotal Resection of Adult Craniopharyngioma: Systematic Review and Meta-Analysis.

OBJECTIVE: The optimal surgical strategy for management of adult patients with craniopharyngioma remains controversial. To analyze the functional outcomes ofadult patients with gross total resection (GTR) and subtotal resection (STR) of craniopharyngioma. METHODS: MEDLINE, EMBASE, Scopus, and Cochrane databases were searched from inception to July 19, 2018, for articles comparing postoperative endocrine function, vision, complications, and recurrence rates for adult patients with GTR and STR of craniopharyngioma. The articles were analyzed by meta-analysis of proportions using a random-effects model to calculate summary odds ratios (ORs). RESULTS: The initial search resulted in 2468 studies and 540 studies selected for full text review. Seventeen studies were included in the final analyses with 748 patients in the GTR cohort and 559 patients in the STR cohort. GTR resulted in a significantly lower likelihood of recurrence when compared with STR (OR, 0.106; 95% confidence interval [CI], 0.067-0.168; P < 0.001), but a significantly greater likelihood of panhypopituitarism (OR, 2.063; 95% CI, 1.058-4.024; P = 0.034) and permanent diabetes insipidus (OR, 2.776; 95% CI, 1.321-5.832; P = 0.007). There was no significant difference between the groups for postoperative worsened vision (P = 0.868), improved vision (P = 0.876), pathologic weight gain (P = 0.724), cerebrospinal fluid leak (P = 0.788), complications (P = 0.656), or death (P = 0.261). CONCLUSIONS: This is the first systematic review of functional outcomes of adult patients with craniopharyngioma. GTR results in decreased likelihood of recurrence, but increased likelihood of postoperative panhypopituitarsm and permanent diabetes insipidus. Surgeons should be aware of these associations when determining the optimal operative strategy for adult patients with craniopharyngioma.

Ectopic Prolactinoma Presenting as Bacterial Meningitis: A Diagnostic Conundrum.

BACKGROUND: Prolactinomas may rarely present with meningitis and cerebrospinal fluid (CSF) rhinorrhea secondary to erosion of the wall of the sella turcica. It is even more uncommon for this abnormal communication to be caused by an ectopic prolactinoma arising from the sphenoid sinus and eroding into the sella. This atypical growth pattern makes diagnosis very difficult because there may be no displacement of the normal pituitary gland. The first reported case of a patient with an ectopic prolactinoma originating within the sphenoid sinus presenting primarily with meningitis is presented, and the management strategy and surgical and nonsurgical treatment options are discussed. CASE DESCRIPTION: A 48-year-old woman presented with confusion, low-pressure headache, and fever. A lumbar puncture revealed Streptococcus pneumoniae meningitis, and she was placed on intravenous penicillin G. After initiation of antibiotics, she noticed salty tasting postnasal fluid leakage. Imaging was remarkable for bony erosion of the sphenoid sinus wall by a soft tissue mass growing from within the sinus, with no disruption of the normal pituitary gland. A biopsy was then performed with an endoscopic transnasal transsphenoidal approach, and the CSF leak was repaired with a pedicled nasoseptal flap. The final pathology was prolactinoma, and she was placed on cabergoline. CONCLUSIONS: Ectopic prolactinomas may rarely present as meningitis secondary to retrograde transmission of bacteria through a bony defect in the sphenoid sinus, and must be included in the differential diagnosis of any sphenoid sinus mass. Management should first address the infection, followed by surgical repair of the bony defect.

Results of Percutaneous Balloon Compression in Trigeminal Pain Syndromes.

OBJECTIVE: To investigate initial pain relief and subsequent recurrence after percutaneous balloon compression (PBC) and describe its association with the nature of trigeminal pain, previous procedures, or other clinical factors. METHODS: A total of 222 patients with medically refractory trigeminal pain treated with PBC at Mayo Clinic Florida between 1998 and 2017 were enrolled into this study. Patients were divided into those with typical trigeminal neuralgia (TN) and those with atypical trigeminal pain. The postprocedural rate of pain recurrence and associations between patient characteristics and recurrence were studied. RESULTS: One hundred fifty-two patients had TN and 70 patients had atypical pain. At the last follow-up, 158 patients had excellent pain relief, 37 had good pain relief, 11 had fair pain relief, and 16 had poor pain relief. The median duration of follow-up was 31.1 months. Patients with atypical pain were less likely to have an excellent result compared with patients with typical pain (61.4% vs. 82.9%; P < 0.001). Recurrence was observed in 103 patients (46.4%) and was associated with previous procedures (hazard ratio, 1.658; 95% confidence interval, 1.09-2.49; P = 0.017). Other clinical factors were not significant. CONCLUSIONS: Our study demonstrates the safety and efficacy of PBC, with 88% of patients pain-free at last follow-up. Patients with atypical pain have worse outcomes, and patients with previous procedures have a higher risk of recurrence. Repeat surgery does not decrease efficacy. We recommend conservative parameter selection at the initial procedure.

Primary histiocytic sarcoma of the central nervous system: a case report with platelet derived growth factor receptor mutation and PD-L1/PD-L2 expression and literature review.

BACKGROUND: Histiocytic sarcoma (HS) is an aggressive malignant neoplasm. HS in the central nervous system is exceptionally rare and associated with a poor prognosis. This report documents a case of primary HS of the central nervous system with treatment including surgery, radiotherapy, and chemotherapy. CASE PRESENTATION: Our patient was a 47 year old female presenting with progressive ataxia, headaches, imbalance, nausea, vomiting, and diplopia. MRI showed a heterogeneously enhancing lesion approximately 2.9 × 3.0 × 2.3 cm centered upon the cerebellar vermis with mild surrounding vasogenic edema and abnormal enhancement of multiple cranial nerves. The patient underwent surgical debulking, which revealed histiocytic sarcoma with grossly purulent drainage. Staging revealed diffuse leptomeningeal involvement, primarily involving the brain and lower thoracic and lumbar spine. She underwent adjuvant radiotherapy to the brain and lower spine and was started on high dose methotrexate. However, she experienced progressive disease in the cervical and thoracic spine as well as pulmonary involvement. Genomic sequencing of her tumor showed a mutation in the platelet-derived growth factor receptor A (p.V0681) which could be targeted with Dasatinib. However, she did not tolerate Dasatinib and she succumbed to progressive disseminated disease eight months from original diagnosis. Our pathologic evaluation also revealed expression of PD-L1 and PD-L2 by tumor cells raising the potential therapeutic role for immune checkpoint inhibition. CONCLUSIONS: This case provides an example of effective CNS control with resection and moderate doses of radiation therapy. A review of the literature confirms aggressive multidisciplinary treatment is the most effective treatment against this disease. In addition, genomic sequencing may play an important role in determining new therapeutic options. However, CNS histiocytic sarcoma remains an aggressive disease with a propensity for early widespread dissemination and few long term survivors.

Stem cell therapy and its potential role in pituitary disorders.

PURPOSE OF REVIEW: The pituitary gland is one of the key components of the endocrine system. Congenital or acquired alterations can mediate destruction of cells in the gland leading to hormonal dysfunction. Even though pharmacological treatment for pituitary disorders is available, exogenous hormone replacement is neither curative nor sustainable. Thus, alternative therapies to optimize management and improve quality of life are desired. RECENT FINDINGS: An alternative modality to re-establish pituitary function is to promote endocrine cell regeneration through stem cells that can be obtained from the pituitary parenchyma or pluripotent cells. Stem cell therapy has been successfully applied to a plethora of other disorders, and is a promising alternative to hormonal supplementation for resumption of normal hormone homeostasis. SUMMARY: In this review, we describe the common causes for pituitary deficiencies and the advances in cellular therapy to restore the physiological pituitary function.

Infection or Glioma? The False Dilemma of Primary Central Nervous System Histiocytic Sarcoma.

BACKGROUND: Primary central nervous system (CNS) histiocytic sarcoma is an extremely rare lymphoproliferative disorder that affects the CNS and behaves aggressively. Only 27 cases of primary CNS histiocytic sarcoma have been reported. The paucity of literature on this entity has made diagnosis and treatment difficult both for the surgeon and the pathologist. CASE DESCRIPTION: In this case of primary CNS histiocytic sarcoma, a middle-aged woman presented from an outside institution with a supposed cerebellar abscess. Intraoperative frozen pathology was initially interpreted as high-grade glioma; however, final pathology demonstrated histiocytic sarcoma. CONCLUSIONS: This report makes a significant contribution to the literature on this rare malignant disease by outlining a similar presentation among several cases and providing a thorough overview of existing criteria for diagnosis and management.

Technical feasibility and safety of image-guided parieto-occipital ventricular catheter placement with the assistance of a wearable head-up display.

BACKGROUND: Wearable technology is growing in popularity as a result of its ability to interface with normal human movement and function. METHODS: Using proprietary hardware and software, neuronavigation images were captured and transferred wirelessly via a password-encrypted network to the head-up display. The operating surgeon wore a loupe-mounted wearable head-up display during image-guided parieto-occipital ventriculoperitoneal shunt placement in two patients. RESULTS: The shunt placement was completed successfully without complications. The tip of the catheter ended well within the ventricles away from the ventricular wall. The wearable device allowed for continuous monitoring of neuronavigation images in the right upper corner of the surgeon's visual field without the need for the surgeon to turn his head to view the monitors. CONCLUSIONS: The adaptable nature of this proposed system permits the display of video data to the operating surgeon without diverting attention away from the operative task. This technology has the potential to enhance image-guided procedures.

Balloon kyphoplasty for vertebral compression fractures in solid organ transplant recipients: results of treatment and comparison with primary osteoporotic vertebral compression fractures.

BACKGROUND CONTEXT: Balloon kyphoplasty has become established as a useful treatment for vertebral compression fractures (VCF) associated with primary osteoporosis and osteolytic tumors. Organ transplant recipients are also at risk for VCF because of their underlying disease process and because they require long-term treatment with steroids and other immunosuppressive drugs. PURPOSE: To explore whether balloon kyphoplasty is an effective treatment for VCF that develop in solid organ transplant recipients. A secondary goal was to determine whether there are any differences between VCF in transplant patients and VCF in patients with primary osteoporosis, with respect to disease severity and new fracture development. STUDY DESIGN: Prospective, longitudinal clinical series. PATIENT SAMPLE: The transplant group included 10 consecutive transplant patients (9 liver and 1 kidney), with a total of 29 symptomatic VCFs. The comparison group included 10 consecutive patients with primary osteoporosis and no history of organ transplantation, with a total of 15 VCFs. OUTCOME MEASURES: The primary clinical end point was back pain, measured using the Visual Analog Scale (VAS), which was recorded at baseline, and 1 and 12 months postprocedure. Radiographic evaluation included measurement of Cobb angles for each treated vertebral segment on preprocedure and 1-month postprocedure lateral radiographs. An improvement of >5 degrees was considered significant. The number of fractures seen at the time of diagnosis and the number of new fractures occurring during the follow-up period were recorded. METHODS: Balloon kyphoplasty was performed at all symptomatic levels. All fractures were treated within 3 months of onset. Patient follow-up was 12 months. RESULTS: The transplant group had significantly higher levels of pain at baseline, (mean VAS 9.3 and 7.7 for the transplant group and primary osteoporosis group, respectively: p=.013). After treatment, the VAS decreased to 3.2 in the transplant group and 1.5 in the comparison group. Improvement was highly significant in both groups (p<.001), and was maintained at 12-month follow-up. Sagittal alignment was improved by >5 degrees in three patients in each group (30%). There were no procedural complications in either group. Compared with the primary osteoporosis group, the transplant group was more likely to have multiple fractures at the time of diagnosis (2.9 vs. 1.5, p=.03), had a twofold greater incidence of new fractures during the follow-up period (40% vs. 20%), was more than a decade younger (64 vs. 75 years, p<.01), was much more likely to have received chronic immunosuppressive therapy with glucocorticoids and calcineurin phosphate inhibitors (100% vs. 0%, p<.001), and had a higher percentage of males (70% vs. 10%, p=.02), CONCLUSIONS: These data suggest that balloon kyphoplasty can be performed safely in organ transplant recipients with VCFs. The degree of pain relief is equivalent to that seen in patients with primary osteoporosis. Results are durable at 12-month follow-up. Transplant patients developed earlier and more severe bony disease, with more severe baseline pain, a higher incidence of multiple fractures at the time of diagnosis, and a greater risk of new fracture development posttreatment, as compared with the primary osteoporosis group.

Clinical presentation and surgical management of dissecting posterior inferior cerebellar artery aneurysms: 2 case reports.

Intracranial dissection presenting with subarachnoid hemorrhage (SAH) most commonly involves the vertebral artery. The natural history of this lesion suggests frequent early rehemorrhage and need for urgent treatment. Isolated dissection of the posterior inferior cerebellar artery (PICA) is very rare. We present 2 cases of isolated PICA dissections presenting with SAH. Both patients were middle-aged men who presented with transient loss of consciousness, severe headache, and cranial neuropathies. Initial angiography showed dilatation and narrowing of PICA consistent with dissection and aneurysm formation. The vertebral arteries were normal and there was no other cause for the SAH. Repeat angiography 2 weeks after admission revealed significant enlargement of the aneurysmal dilation of the dissected segment of PICA in both patients. Both patients were treated operatively. One patient had clip reconstruction of the PICA with preservation of flow through the PICA. Follow-up angiography one year later showed no recurrence. The other patient underwent direct surgical trapping and resection of the dissected segment of PICA after passing balloon occlusion testing at the vertebral-PICA junction. Both patients have more than 2 years of clinical follow-up and remain well. Isolated PICA dissection seems to have a less ominous natural history compared to vertebral artery dissection. These lesions need to be followed carefully for evidence of aneurysmal enlargement. Direct surgical reconstruction of the dissected segment may be possible. Balloon occlusion testing may be very helpful in determining if the involved PICA segment can be sacrificed.

Preliminary results of balloon kyphoplasty for vertebral compression fractures in organ transplant recipients.

OBJECT: Organ transplant recipients are at risk for vertebral compression fractures (VCFs). The goal of this study was to determine whether kyphoplasty is an effective treatment for VCFs that develop in this patient population. METHODS: Six consecutive patients who had undergone an organ transplant (five liver and one kidney transplant) had a total of 13 symptomatic VCFs that were treated with balloon kyphoplasty. Postprocedure follow-up duration ranged from 6 to 12 months. The mean visual analog scale pain score was 9.3 before treatment and declined to 1.8 after treatment. This improvement was highly significant (p < 0.001). Intake of narcotic drugs decreased or was eliminated in all patients, and there were no complications related to the procedure. There was one instance of clinically insignificant extraosseous cement extravasation. Sagittal alignment was improved by 5 degrees in one patient and was unchanged in the remaining five. During the follow-up period, a new fracture developed adjacent to a treated level in one patient. This was successfully treated with an additional kyphoplasty procedure. CONCLUSIONS: Kyphoplasty can be performed safely in organ transplant recipients with VCF, in whom results are just as favorable as those seen in patients with no history of organ transplantation.

Lumbar peritoneal shunting with video-laparoscopic assistance: a useful technique for the management of refractory postoperative lumbar CSF leaks.

BACKGROUND: Cerebrospinal fistulas and pseudomeningoceles can occur after lumbar spinal surgery, and are sometimes refractory to direct repair, external drainage, and blood patches. The authors report a technique for cerebrospinal fluid (CSF) diversion from the lumbar spine to the peritoneum to assist with the management of these difficult situations. METHODS: Using video-laparoscopic assistance, two shunts are placed from the lumbar region into the peritoneal cavity: first, a lumbar subarachnoid space to peritoneum shunt; and second, a meningocele cavity to peritoneum shunt. Patients are ambulated immediately after the procedure. External drains are not used. RESULTS: Four patients with refractory CSF leaks were successfully managed with this technique. Complications associated with prolonged bedrest and external drains were avoided. Ancillary procedures were minimized, and hospital stay was shortened. Laparoscopic assistance offered verification of accurate placement of the peritoneal catheter and shortened operative times. CONCLUSIONS: Dual lumbar peritoneal shunts (intrathecal-peritoneal and meningocele cavity-peritoneal), placed with laparoscopic assistance, proved effective in the management of four patients with postoperative lumbar CSF leaks, who had failed to respond to conventional treatment.

Lateral mass screw-rod fixation of the cervical spine: a prospective clinical series with 1-year follow-up.

BACKGROUND CONTEXT: Lateral mass plating has become the technique of choice for posterior cervical fixation. Although these systems are safe and reliable, they can be difficult to use in patients with abnormal cervical anatomy; screw placement can be compromised by the fixed hole spacing of the plate; screw back-out and other forms of implant failure can occur; and extension across the cervicothoracic junction can be problematic. PURPOSE: To report a series of patients undergoing posterior cervical stabilization with a polyaxial screw-rod construct and to investigate whether this new system offers any advantages over existing methods of fixation. STUDY DESIGN: A prospective study evaluating clinical and radiographic parameters in a consecutive series of patients treated with this technique. PATIENT SAMPLE: There were 21 patients in the study group. The surgical indication was cervical spondylosis in 14, trauma in 2, postsurgical kyphosis in 2 and 1 case each of congenital cervicothoracic stenosis, C7-T1 pseudarthrosis and basilar invagination with brainstem compression. OUTCOME MEASURES: Clinical indicators included age, gender, neurologic status, surgical indication and number of levels stabilized. Note was made of whether laminectomy and concomitant anterior reconstructive surgery were performed. Radiographic indicators included early postoperative computed tomography (CT) scan to check for screw placement and plain radiographs at subsequent visits. METHODS: The participants in this study underwent posterior cervical stabilization using lateral mass screw-rod fixation. Clinical and radiographic assessment was carried out immediately after surgery, and 3, 6 and 12 months after surgery. One-year follow-up was obtained in all cases. RESULTS: A total of 212 screws were implanted in 21 patients. Fixation was carried out over an average of 5.5 spinal segments (range, 2 to 11). The system was successfully implanted in all patients despite the presence of coronal and sagittal plane deformities and/or lateral mass abnormalities in the majority of cases. This system allowed for screw placement in the occiput, C1 lateral mass, C2 pars, C3-C7 lateral masses and upper thoracic pedicles. Early postoperative CT scanning confirmed satisfactory screw placement in all cases. Three patients experienced transient single-level radiculopathy, for an incidence of 1.4% per screw placed. Two patients developed wound seromas requiring evacuation. There were no infections or other wound healing problems. There were no examples of cord or vertebral artery injury, cerebrospinal fluid leak, screw malposition or back-out, loss of alignment or implant failure. When compared with plating techniques, screw-rod fixation appeared to offer several advantages. First, unlike plates, rods proved to be amenable to multiplanar contouring, which is often needed for deformities associated with cervical spondylosis. Second, lateral mass screw placement was more precise because it was not constrained by the hole spacing of the plate. Third, screw back-out and other types of implant failure were not seen. Fourth, the screw-rod system was more easily extended to the occiput and across the cervicothoracic junction. Fifth, the screw-rod system permitted the application of compression, distraction and reduction forces within the construct, to a greater extent than plate systems. The incidence of postoperative radiculopathy was similar to that seen with plate systems. CONCLUSIONS: These data indicate that posterior cervical stabilization with polyaxial screw-rod fixation is a safe, straightforward technique that appears to offer some advantages over existing methods of fixation. Results appear to be durable at 1-year follow-up. Benefits are more significant with longer constructs, especially those extending to the occiput or crossing the cervicothoracic junction.

Radiographic fusion rate after implantation of facet bone dowels.

BACKGROUND CONTEXT: Achieving a posterolateral fusion in conjunction with performing decompressive laminectomies can prevent recurrence of stenosis or worsening of spondylolisthesis. Facet bone dowels have been introduced and marketed as a less invasive alternative to pedicle screws. Surgeons have been placing them during lumbar laminectomy surgery and coding for intervertebral biomechanical device and posterolateral fusion. These bone dowels have also been placed percutaneously in outpatient surgery centers and pain clinics for facet-mediated back pain. PURPOSE: To describe fusion outcomes in patients who underwent facet bone dowel placement. STUDY DESIGN/SETTING: Retrospective analysis of a single center's experience. PATIENT SAMPLE: Ninety-six patients comprise the entire cohort of patients who underwent facet bone dowel implantation at our institution with adequate postoperative imaging to determine fusion status. OUTCOME MEASURES: Fusion rates as determined on postoperative computed tomography (CT) scans and dynamic lumbar X-rays if CT is not available. METHODS: Threaded facet bone dowels in this study were placed according to the manufacturer's recommended methods. The bone dowels were placed after open exploration of the facet complex or percutaneously through a tubular retractor on the contralateral side from a microdiscectomy or synovial cyst resection. The most recent available postoperative imaging was reviewed to determine fusion status. RESULTS: Of 96 patients in our series, 6 (6.3%) had a fusion seen on CT and 4 did not exhibit any movement on dynamic lumbar X-rays for a total fusion rate of 10.4% (10/96). Eighty-six (89.6%) patients were shown on imaging to not have a solid fusion either by visualizing a patent facet joint on CT or measurable movement between the flexion and the extension lumbar X-rays. CONCLUSIONS: This article is mainly intended to question whether the implantation of facet bone dowels can produce a solid fusion radiographically. In our experience, the placement of facet bone dowels does not equal the time, skill, or attention to detail that is necessary for a posterolateral lumbar arthrodesis, and our follow-up radiographic studies clearly demonstrate an inadequate fusion rate.