Open and endoscopic excision of calvarial dermoid and epidermoid cysts: a single center experience on 128 consecutive cases.

OBJECTIVE: Dermoid and epidermoid cysts rank among the most common pediatric tumors. We analyzed the outcomes of surgical excision of dermal and epidermal inclusion cysts in a large consecutive series of children. METHODS: We retrospectively reviewed 128 consecutive children who underwent calvarial inclusion cyst resection between 2000 and 2010 at NYU Langone Medical Center. Demographic information, neurological exam, lesion location, lesion diameter, type of treatment, extent of resection, time of follow-up, and recurrence were collected. RESULTS: The cohort includes 67 girls (52.3 %) and 61 boys (47.7 %). Age at diagnosis ranged from birth to 6.5 years (mean of 1.2 years) with surgical intervention between 1 month and 20 years of age (1.5 ± 2.1). Of the 128 patients, 107 underwent open resection. Surgical approach was determined by the senior surgeon. Location, postoperative cosmesis, and family preference were the determining factors. Endoscopic resection was favored with supraorbital and glabellar lesions (75 % endoscopic versus 25 % open) using a rigid scope via a single incision. Erosion of the outer table and involvement of the inner table was noted in 20 patients (15 %), 14 of which were reconstructed using a split thickness calvarial graft. These lesions were noted to be significantly larger than lesions where cranioplasty was not used (1.9 ± 2.81 cm versus 1.23 ± 0.98 cm, p = 0.022). Gross total resection was achieved in all cases. DISCUSSION: Complete removal and cure from dermoid and epidermoid inclusion cysts are possible. Complications are few. Endoscopic approaches are useful to improve cosmesis and limit tissue damage for lesions near the orbits.

Impact of starting point and C2 nerve status on the safety and accuracy of C1 lateral mass screws: meta-analysis and review of the literature.

STUDY DESIGN: Literature review and meta-analysis. OBJECTIVE: To compare clinical and radiographic outcomes of patients treated with C1 lateral mass screws (C1LMS), analyzing the impact of screw starting point and C2 nerve sectioning on malposition, vertebral artery injury (VAI), and C2 neuralgia and numbness. BACKGROUND: Various starting points have been suggested for C1LMS insertion. Some advocate sectioning the C2 nerve root to ease placement. METHODS: Online databases were searched for English language articles between 1994 and 2012 reporting on C1LMS. Forty-two studies describing 1471 patients instrumented with 2905 C1LMS met inclusion criteria. Three surgical techniques included posterior arch starting point and center of lateral mass with nerve root preservation or sacrifice. RESULTS: All studies provided class III evidence. Three injuries to the vertebral artery occurred secondary to C1LMS insertion (0.1%) and 5 instances of clinically significant screw malpositions (0.2%). Postoperative imaging revealed 45 malpositioned screws (1.6%) without clinical consequences. Meta-analysis techniques demonstrated that sacrifice of the C2 nerve root caused greater postoperative numbness but less neuralgia and fewer screw malpositions. Similar rates of screw malposition and VAI arose with posterior arch screws and those starting below the arch with C2 nerve preservation, but the latter had greater numbness and pain. CONCLUSION: A thorough understanding of atlantoaxial anatomy and modern surgical techniques renders the insertion of C1LMS safe and accurate. The incidence of clinically significant malpositioned screws or VAI is <0.5%. Sacrifice of the C2 nerve root did result in fewer malpositioned screws. Numbness occurred in 11% of patients, an outcome that may be unacceptable to certain patient populations, but neuropathic pain was nearly absent with nerve sectioning. C2 nerve preservation and retraction for C1 screw placement may have higher incidence of neuropathic pain. Posterior arch screws are a viable option for patients with arches that are of adequate height.

Impact of Starting Point and Bicortical Purchase of C1 Lateral Mass Screws on Atlantoaxial Fusion: Meta-Analysis and Review of the Literature.

STUDY DESIGN: Structured review of literature and application of meta-analysis statistical techniques. OBJECTIVES: Review published series describing clinical and radiographic outcomes of patients treated with C1 lateral mass screws (C1LMS), specifically analyzing the impact of starting point and bicortical purchase on successful atlantoaxial arthrodesis. SUMMARY OF BACKGROUND DATA: Biomechanical studies suggest posterior arch screws and C1LMS with bicortical purchase are stronger than screws placed within the center of the lateral mass or those with unicortical purchase. METHODS: Online databases were searched for English-language articles between 1994 and 2012 describing posterior atlantal instrumentation with C1LMS. Thirty-four studies describing 1247 patients having posterior atlantoaxial fusion with C1LMS met inclusion criteria. RESULTS: All studies provided class III evidence. Arthrodesis was quite successful regardless of technique (99.0% overall). Meta-analysis and multivariate regression analyses showed that neither posterior arch starting point nor bicortical screw purchase translated into a higher rate of successful arthrodesis. There were no complications from bicortical screw purchase. CONCLUSIONS: The Goel-Harms technique is a very safe and successful technique for achieving atlantoaxial fusion, regardless of minor variations in C1LMS technique. Although biomechanical studies suggest markedly increased rigidity of bicortical and posterior arch C1LMS, the significance of these findings may be minimal in the clinical setting of atlantoaxial fixation and fusion with modern techniques. The decision to use either technique must be made after careful review of the preoperative multiplanar computed tomography imaging, assessment of the unique anatomy of each patient, and the demands of the clinical scenario such as bone quality.

Outcome comparison of atlantoaxial fusion with transarticular screws and screw-rod constructs: meta-analysis and review of literature.

STUDY DESIGN: Literature review and meta-analysis. OBJECTIVE: To compare clinical and radiographic outcomes of patients treated with transarticular screws (TASs) and screw-rod constructs (SRCs) for posterior atlantoaxial fusion. BACKGROUND: Modern techniques for C1-C2 fusions include Magerl and Seeman's TAS and SRC using C1 lateral mass screws and C2 pars/pedicle screws as described by Goel and Laheri and later modified by Harms and Melcher. MATERIALS AND METHODS: Online databases were searched for English-language articles between 1986 and April 2011 describing posterior atlantoaxial instrumentation with C1-C2 TAS or SRC. Forty-five studies (2073 patients) treated with TAS and 24 studies (1073 patients) treated with SRC fulfilled inclusion criteria. Standard and formal meta-analysis techniques were used to compare the outcomes. RESULTS: All studies provided class III evidence. There were no differences in 30-day mortality (0.8% vs. 0.6%) or neurological injury (0.2% vs. 0%). There was a higher incidence of vertebral artery injury [4.1% (95% confidence interval (CI), 2.8%-5.4%) vs. 2.0% (95% CI, 1.1%-3.4%); P=0.02] and malpositioned screws [7.1% (95% CI, 5.7%-8.8%) vs. 2.4% (95% CI, 1.1%-4.1%); P<0.001] and a slightly lower rate of fusion with the TAS technique [97.5% (95% CI, 95.9%-98.5%) vs. 94.6% (95% CI, 92.6%-96.1%); P<0.001]. CONCLUSIONS: TAS and SRC are safe and effective treatment options for C1-C2 instability but require a thorough knowledge of atlantoaxial anatomy for successful insertion of screws. Slightly higher rates of fusion and less risk of injury to the vertebral artery during screw placement were observed with the SRC technique. However, differences in graft material and techniques were noted. Prospective, randomized studies with validated radiographic and clinical outcome metrics are necessary for proper comparison of these techniques.

Comparison of screw malposition and vertebral artery injury of C2 pedicle and transarticular screws: meta-analysis and review of the literature.

STUDY DESIGN: Literature review and meta-analysis. OBJECTIVES: To compare the incidence of screw malposition and vertebral artery injury (VAI) with transarticular screws (TAS) and C2 pedicle screws (C2PS) using meta-analysis techniques. SUMMARY OF BACKGROUND DATA: Posterior instrumentation for atlantoaxial fusions can be challenging and risky. Some centers report a higher incidence of VAI with the implantation of TAS compared with C2PS, whereas other data do not support this. METHODS: Online databases were searched for English language articles between 1994 and April 2011 describing the clinical and radiographic outcomes after insertion of C2PS or TAS. Forty-one studies reporting on 3627 TAS and 33 studies describing 2979 C2PS met inclusion criteria for VAI or clinically significant misplacements (VAI, neurological deficits, or misplacements requiring surgical revision), and 36 studies reporting on 3280 TAS and 28 studies describing 2532 C2PS met inclusion criteria for radiographic misplacement outcomes. RESULTS: All studies comprised class III evidence. VAI occurred in 26 of 3627 (0.72%) implanted TAS and in 10 of 2979 (0.34%) implanted C2PS (P=0.01). Clinically significant misplacements occurred in 67 TAS (1.84%) and in 10 C2PS (0.34%; P<0.0001). The point estimate of VAI for TAS was 1.68% [confidence interval (CI), 1.23%-2.29%] and was higher than C2PS (1.09%; CI, 0.73%-1.63%; P=0.01). The point estimate of clinically significant screw malposition for TAS was 2.33% (CI, 1.61%-3.37%) and was higher than that of C2PS (1.15%; CI, 0.77%-1.70%; P<0.001). CONCLUSIONS: With training, experience, and anatomic knowledge, both TAS and C2PS can be inserted accurately and safely. However, improper insertion and VAI can have catastrophic consequences. Our review identified a higher risk of VAI, neurological injury, and clinically significant malpositions with TAS compared with C2PS. These data provide preliminary support for the supposition that C2PS have a lower risk of morbidity.

Efficacy of vagus nerve stimulation over time: review of 65 consecutive patients with treatment-resistant epilepsy treated with VNS > 10 years.

OBJECTIVE: Studies have reported improved seizure control with increased duration of vagus nerve stimulation (VNS) but are prone to methodological biases. We analyzed the efficacy of VNS over time in patients with treatment-resistant epilepsy (TRE) who underwent VNS therapy 10 or more years. METHODS: We retrospectively reviewed 65 consecutive patients (29 females) who underwent VNS therapy ≥ 10 years. The mean age at VNS insertion was 30.0 years. Forty-four adults (≥ 18 years; 67.7%) and 21 children (32.3%) were included. Seizure frequency and antiepileptic drug (AED) regimens were recorded prior to VNS and, following VNS insertion, at 6 months, 1 year, 2 years, and every 2 years thereafter. RESULTS: The mean duration of VNS therapy for this group was 10.4 years, and the mean decrease in seizure frequency at last follow-up was 76.3%. The mean reduction in seizures at 6 months and years 1, 2, 4, 6, 8, and 10 years was 35.7, 52.1, 58.3, 60.4, 65.7, 75.5, and 75.5%, respectively. Seizure frequency was significantly reduced from baseline at each of the recorded intervals (P<0.001). There was a trend toward increased AED burden in the latter years of the follow-up period. CONCLUSION: Following a "ramp-up" and accommodation period throughout the initial 24 months after VNS implantation, seizure control improved slightly over the subsequent years of therapy and eventually stabilized. Variation in seizure frequency, however, was common, and frequent changes in AED regimens or stimulation parameters were likely an important and possibly synergistic component of seizure control.

Vagus nerve stimulation in 436 consecutive patients with treatment-resistant epilepsy: long-term outcomes and predictors of response.

OBJECTIVE: The goal of this study was to assess the efficacy and safety of vagus nerve stimulation in a consecutive series of adults and children with treatment-resistant epilepsy (TRE). METHODS: In this retrospective review of a prospectively created database of 436 consecutive patients who underwent vagus nerve stimulator implantation for TRE between November 1997 and April 2008, there were 220 (50.5%) females and 216 (49.5%) males ranging in age from 1 to 76 years at the time of implantation (mean: 29.0 ± 16.5). Thirty-three patients (7.6%) in the primary implantation group had inadequate follow-up (<3 months from implantation) and three patients had early device removal because of infection and were excluded from seizure control outcome analyses. RESULTS: Duration of vagus nerve stimulation treatment varied from 10 days to 11 years (mean: 4.94 years). Mean seizure frequency significantly improved following implantation (mean reduction: 55.8%, P<0.0001). Seizure control ≥ 90% was achieved in 90 patients (22.5%), ≥ 75% seizure control in 162 patients (40.5%), ≥ 50% improvement in 255 patients (63.75%), and <50% improvement in 145 patients (36.25%). Permanent injury to the vagus nerve occurred in 2.8% of patients. CONCLUSION: Vagus nerve stimulation is a safe and effective palliative treatment option for focal and generalized TRE in adults and children. When used in conjunction with a multidisciplinary and multimodality treatment regimen including aggressive antiepileptic drug regimens and epilepsy surgery when appropriate, more than 60% of patients with TRE experienced at least a 50% reduction in seizure burden. Good results were seen in patients with non-U.S. Food and Drug Administration-approved indications. Prospective, randomized trials are needed for patients with generalized epilepsies and for younger children to potentially expand the number of patients who may benefit from this palliative treatment.

Fusiform dilation of the carotid artery following radical resection of pediatric craniopharyngiomas: natural history and management.

OBJECT: Fusiform dilation of the supraclinoid internal carotid artery (FDCA) is a reported occurrence following surgery for suprasellar tumors, in particular craniopharyngiomas. We report our experience of the incidence and natural history of FDCA following aggressive surgical resection of craniopharyngiomas in children. METHODS: Between 1986 and 2006, 86 patients under the age of 21 underwent radical resection of craniopharyngiomas at our institution. Ten cases with < 1 year of follow-up imaging (6), perioperative death (3), or nonsuprasellar tumors (1) were excluded. Data were retrospectively collected on the remaining 76 patients (43 male, 33 female; mean age 9.5 years; mean tumor size 3.3 cm) to determine the risk factors for and the rate and clinical significance of FDCA. RESULTS: Fifty patients had primary tumors and 26 patients received treatment before referral to our center. Sixty-six children (87%) had gross-total resection. At a mean follow-up time of 9.9 years, FDCA had developed in 7 patients (9.2%), all of whom had primary tumors and gross-total resection. The mean time to onset of FDCA was 6.8 months (range 3-11 months) with stabilization occurring at mean of 17.7 months (range 9-29.5 months). The mean size of the aneurysms was 9.1 mm (range 7.1-12 mm). After arrest, no lesions showed continued growth on serial imaging or produced symptoms or required treatment. There were no significant differences in age, sex, tumor size, pre- or retrochiasmatic location, extent of resection, or surgical approach (p > 0.05) between patients with and without FDCA. CONCLUSIONS: Fusiform dilation of the supraclinoid internal carotid artery occurred in almost 10% of children following radical resection of craniopharyngiomas. In agreement with other reports, the authors concluded that FDCA probably occurs as a result of surgical manipulation of the supraclinoid carotid artery and should be managed conservatively because very few patients exhibit continued symptoms or experience growth or rupture of the lesion.

Craniopharyngioma Clinical Status Scale: a standardized metric of preoperative function and posttreatment outcome.

OBJECT: Controversy persists concerning the optimal treatment of craniopharyngiomas in children, and no standard outcome metric exists for comparison across treatment modalities, nor is there one that adequately reflects the multisystem dysfunction that may arise. METHODS: The authors retrospectively analyzed the records of 86 consecutive children who underwent a uniform treatment paradigm of attempted radical resection performed by a single surgeon. Excluding 3 perioperative deaths and 3 patients with inadequate follow-up, 80 children (34 girls and 46 boys; mean age 9.56 years; mean follow-up 9.6 years) composed the study group (53 primary and 27 previously treated/recurrent tumors). Building on existing classification schemes proposed by De Vile for hypothalamic dysfunction and Wen for overall functional outcome, the authors devised a more nuanced classification system (Craniopharyngioma Clinical Status Scale [CCSS]) that assesses outcome across 5 axes, including neurological examination, visual status, pituitary function, hypothalamic dysfunction, and educational/occupational status at last follow-up (there is a 4-tiered grading scale in each domain, with increasing values reflecting greater dysfunction). RESULTS: There was a significant increase in pituitary dysfunction following treatment-consistent with the high rates of diabetes insipidus and hypopituitarism common to the surgical management of craniopharyngiomas-and less dramatic deterioration in hypothalamic function or cognitive domains. Significant improvement in vision was also demonstrated, with no significant overall change in neurological status. Preoperative CCSS scores predicted postoperative outcome better than clinical characteristics like patient age, sex, tumor size, and the location or presence of hydrocephalus. CONCLUSIONS: Preoperative CCSS scores predicted outcome with higher accuracy than clinical or imaging characteristics. In lieu of randomized trials, the CCSS may provide a useful outcome assessment tool for comparison across treatment paradigms and surgical approaches. Long-term follow-up is critical to the analysis of outcomes of craniopharyngioma treatment, given the often-delayed sequelae of all therapies and the high recurrence rates of these tumors.

Refractory epilepsy in tuberous sclerosis: vagus nerve stimulation with or without subsequent resective surgery.

OBJECTIVE: The goal of the work described here was to assess the efficacy and safety of vagus nerve stimulation in a cohort of patients with tuberous sclerosis complex with refractory epilepsy. Furthermore, we examined the impact of vagus nerve stimulation failure on the ultimate outcome following subsequent intracranial epilepsy surgery. METHODS: A retrospective review was performed on 19 patients with refractory epilepsy and TSC who underwent vagus nerve stimulator (VNS) implantation. There were 11 (58%) females and 8 (42%) males aged 2 to 44 years when the VNS was implanted (mean: 14.7+/-12 years). Twelve patients underwent primary VNS implantation after having failed a mean of 7.1 antiepileptic drugs. Two patients (17%) had generalized epilepsy, one had a single seizure focus, three (25%) had multifocal epilepsy, and six (50%) had multifocal and generalized epilepsy. Seven patients were referred for device removal and evaluation for intracranial procedures. One patient in the primary implantation group was lost to follow-up and excluded from outcome analysis. RESULTS: All implantations and removals were performed without permanent complications. The duration of treatment for primary VNS implants varied from 8.5 months to 9.6 years (mean: 4.9 years). Mean seizure frequency significantly improved following VNS implantation (mean reduction: 72%, P<0.002). Two patients had Engel Class I (18%), one had Class II (9%), seven had Class III (64%), and one had Class IV (9%) outcome. Three patients with poor response to vagus nerve stimulation therapy at our center underwent resection of one or more seizure foci (Engel Class I, two patients; Engel Class III, one patient). Seven patients referred to our center for VNS removal and craniotomy underwent seizure focus resection (6) or corpus callosotomy (1) (Engel Class II: 2, Engel III: 2; Engel IV: 3). In total, 8 of 10 (80%) patients experienced improved seizure control following intracranial surgery (mean reduction: 65%, range: 0-100%, P<0.05). CONCLUSIONS: VNS is a safe and effective treatment option for medically refractory epilepsy in patients with tuberous sclerosis complex. Nine of 11 patients (82%) experienced at least a 67% reduction in seizure burden. Lack of response to vagus nerve stimulation does not preclude subsequent improvement in seizure burden with intracranial epilepsy surgery.

Determination of GP88 (progranulin) expression in breast tumor biopsies improves the risk predictive value of the Nottingham Prognostic Index.

BACKGROUND: The Nottingham Prognostic Index (NPI), which combines numerical values for nodal status, tumor size and histological grade, is used in the standard of care to provide predictive value information on post-surgery survival for patients with primary breast cancer. Attempts to improve the performance of the NPI algorithm have been carried out by testing the inclusion of other biomarker expression and morphological features such as vascular invasion. In the present study, we investigated whether expression of the autocrine growth and survival factor GP88 (progranulin), known to be overexpressed in breast cancer, would improve NPI's predictive value. METHODS: We examined by immunohistochemistry (IHC) the GP88 expression in 508 cases of estrogen receptor positive invasive ductal carcinoma with known clinical outcomes and for which NPI had been determined. GP88 IHC expression was scored by two board certified pathologists and classified into two score groups of GP88 <3+ (0, 1+, 2+) and GP88 = 3+. The correlation between GP88 scoring, NPI and disease-free (DFS) or overall survival (OS) outcomes was then examined by Kaplan-Meier analysis, Cox proportional Hazard (CPH) ratio and Pearson's X (2) test. RESULTS: Kaplan-Meier survival graphs of cases categorized by their NPI scores (<3.4, 3.4-5.4, >5.4) and GP88 expression showed that for patients within the same NPI subgroup, patients having tumors with a high GP88 expression (GP88 IHC score of 3+) had a worse DFS than patients with tumors that had a low GP88 expression (GP88 IHC score <3+). When adjusted for NPI, high GP88 score was significantly associated with recurrence with a hazard ratio of 3.30 (95 % CI 2.12 to 5.14). CONCLUSIONS: The data suggest that the determination of GP88 tumor expression at time of diagnosis for early stage breast cancer patients can provide additional survival information to that provided by NPI alone and thus may be useful for risk management of patients diagnosed with breast cancer.

The prevalence of the ponticulus posticus (arcuate foramen) and its importance in the Goel-Harms procedure: meta-analysis and review of the literature.

OBJECTIVE: We reviewed published radiographic and cadaver series describing the incidence of the anatomical anomaly ponticulus posticus and discuss its relevance to C1 lateral mass screw (C1LMS) insertion. METHODS: Online databases were searched for English-language articles describing the presence of ponticulus posticus in cadaver and radiographic studies. Forty-four reports describing 21,789 patients (n = 15,542) or bony/cadaver specimens (n = 6247) fulfilled inclusion criteria. Meta-analysis techniques were applied to estimate the prevalence of this anomaly. RESULTS: The overall prevalence of ponticulus posticus was 16.7%. The anomaly was identified in 18.8% of cadaver, 17.2% of computed tomographic, and 16.6% on radiographic studies. The anomaly composed a complete foramen in 9.3% of patients and was partial/incomplete in 8.7%. It was present bilaterally in 5.4% of cases and unilateral in 7.6%. There was no significant difference in prevalence between males (15.8%) and females (14.6%). Review of that literature demonstrated a dramatic increase in the number of patients treated with C1LMS through the posterior arch since first described in 2002, necessitating recognition of this anomaly when performing the Goel-Harms procedure. CONCLUSION: The atlantal anomaly ponticulus posticus is not rare, occurring in 16.7% of patients in radiographic and cadaver studies. This anomaly may give the false impression that the posterior arch of the atlas is of adequate size to accommodate a C1LMS and may lead to inadvertent vertebral artery injury. Careful assessment via preoperative multiplanar computed tomographic imaging should be performed before consideration of C1LMS implantation.

Atlantoaxial fusion with screw-rod constructs: meta-analysis and review of literature.

OBJECTIVE: To review published series describing C1-2 posterior instrumented fusions and summarize clinical and radiographic outcomes of patients treated with screw-rod constructs (SRC). METHODS: Online databases were searched for English-language articles published between 1991 and April 2011 describing posterior atlantoaxial instrumentation with C1-2 SRC. There were 24 studies including 1073 patients treated with SRC that fulfilled inclusion criteria. Meta-analysis techniques were used to compare outcomes. RESULTS: All studies provided class III evidence. The 30-day perioperative mortality rate was 0.6%, and neurologic injury occurred in two patients with vertebral artery injury (VAI) from screw malpositions (0.2%). The incidence of clinically significant screw malpositions was 2.4% (confidence interval [CI], 1.1%-4.1%), the incidence of VAI was 2.0% (CI, 1.1%-3.4%), and the rate of fusion with the SRC technique was 97.5% (CI, 95.9%-98.5%). CONCLUSIONS: SRC is a safe and effective treatment option for C1-2 instability. The low but nonzero incidence of screw malposition and VAI emphasizes the necessity of having a thorough knowledge of atlantoaxial anatomy for successful insertion of screws.

Suprasellar hamartoma and arachnoid cyst.

OBJECTIVE: The differential diagnosis for suprasellar masses includes a variety of pathologies, ranging from stable and benign lesions to aggressive and malignant ones. We report a case of a suprasellar hamartoma associated with an arachnoid cyst and review the literature surrounding the topic. CASE DESCRIPTION: A 32-year-old man who presented with headaches and nonspecific vision loss was found to have a cystic, calcified, and minimally contrast enhancing lesion of the suprasellar region. Intraoperative inspection revealed a discrete mass in the right side of suprasellar region that resembled normal brain completely enveloped by the basal arachnoid membranes including the membrane of Lillequist and was not connected to the brain. Fenestration and exploration of the cystic portion demonstrated a simple arachnoid cyst filled with what appeared to be cerebrospinal fluid. Given the adherence of the lesion to numerous perforating arteries arising from the posterior communicating artery, a biopsy with intraoperative confirmation was taken. Pathology was consistent with neuroglial tissue without evidence of neoplasia. CONCLUSIONS: To our knowledge this is only the third case of an isolated suprasellar hamartoma described in the literature and the first of its kind to be associated with an arachnoid cyst.

Outcomes of fusion for lateral atlantoaxial osteoarthritis: meta-analysis and review of literature.

OBJECTIVE: Atlantoaxial osteoarthritis (AAOA) is an underrecognized source of neck pain, limitation of range of motion, and cervicogenic headaches. When conservative treatments such as facet injections fail, fusion may be indicated. We reviewed published series describing posterior fusions for atlantoaxial osteoarthritis of the facet joints. METHODS: Online databases were searched for English-language articles describing the diagnosis and treatment of AAOA. Twenty-three studies reporting on 246 patients treated with posterior fusion for lateral AAOA fulfilled inclusion criteria. Standard statistical and formal meta-analytic techniques were used to assess outcomes. RESULTS: All studies provided class III evidence. The 30-day perioperative mortality was 1.2% and neurologic injury did not occur. Patients were followed for a mean of nearly 5 years. Fusion was successful in 98% of patients with a single operation and with 99.5% of patients after revision surgery. Intractable preoperative neck pain either resolved completely or improved in 97.7% of patients. Using meta-analytic techniques, the point estimate for improvement or resolution of pain was 92.6% (confidence interval = 86.8%-96.0%) and the rate of arthrodesis for AAOA was 92.2% (confidence interval = 85.6%-95.9%) and there were no differences among the various techniques used for fusion. Operative complications were few. CONCLUSIONS: Posterior C1-2 fusion is a safe and effective treatment option for patients with intractable neck pain secondary to lateral AAOA. Modern fusion options offer a high rate of arthrodesis and low risk of morbidity if conservative therapies fail to provide adequate pain relief.

Atlantoaxial fusion with transarticular screws: meta-analysis and review of the literature.

OBJECTIVE: To review published series describing C1-2 posterior instrumented fusions and summarize clinical and radiographic outcomes of patients treated with transarticular screw (TAS) fixation. METHODS: Online databases were searched for English-language articles published between 1986 and April 2011 describing posterior atlantoaxial instrumentation with C1-2 TAS fixation. There were 45 studies including 2073 patients treated with TAS that fulfilled inclusion criteria. Meta-analysis techniques were used to calculate outcomes. RESULTS: All studies provided class III evidence. The 30-day perioperative mortality rate was 0.8%, and the incidence of neurologic injury was 0.2%. The incidence of clinically significant malpositioned screws was 7.1% (confidence interval [CI], 5.7%-8.8%), the incidence of vertebral artery injury was 3.1% (CI, 2.3%-4.3%), and the rate of fusion with the TAS technique was 94.6% (CI, 92.6%-96.1%). CONCLUSIONS: TAS fixation is a safe and effective treatment option for C1-2 instability with high rates of fusion (approximately 95%). Screw malposition and vertebral artery injury occurred in approximately 5% of patients. The successful insertion of TAS requires a thorough knowledge of atlantoaxial anatomy.

Is external cervical orthotic bracing necessary after posterior atlantoaxial fusion with modern instrumentation: meta-analysis and review of literature.

BACKGROUND: No guidelines exist regarding external cervical orthoses (ECO) after atlantoaxial fusion. We reviewed published series describing C1-2 posterior instrumented fusions with screw-rod constructs (SRC) or transarticular screws (TAS) and compared rates of fusion with and without postoperative ECO. METHODS: Online databases were searched for English-language articles between 1986 and April 2011 describing ECO use after posterior atlantoaxial instrumentation with SRC or TAS. Eighteen studies describing 947 patients who had SRC (± ECO: 254 of 693 patients), and 33 studies describing 1424 patients with TAS (± ECO: 525 of 899 patients) met inclusion criteria. Meta-analysis techniques were applied to estimate rates of fusion with and without ECO use. RESULTS: All studies provided class III evidence, and no studies directly compared outcomes with or without ECO use. There was no significant difference in the proportion of patients who achieved successful fusion between patients treated with ECO and without ECO for SRC or TAS patients. Point estimates and 95% confidence intervals (CI) for rates of fusion ± ECO were 97.4% (CI: 95.2% to 98.6%) versus 97.9% (CI: 93.6% to 99.3%) for SRC and 93.6% (CI: 90.7% to 95.6%) versus 95.3% (CI: 90.8% to 97.7%) for TAS. There was no correlation between duration of ECO treatment and fusion (dose effect). CONCLUSIONS: After C1-2 fusion with modern instrumentation, ECO may be unnecessary (class III). Some centers recommend ECO use with patients with softer bone quality (class IV). Prospective, randomized studies with validated radiographic and clinical outcome metrics are necessary to determine the utility of ECO after C1-2 fusion and its impact on patient comfort and cost.

Anterior temporal lobectomy with amygdalohippocampectomy for mesial temporal sclerosis: predictors of long-term seizure control.

OBJECT: In this paper the authors' goal was to identify preoperative variables that predict long-term seizure freedom among patients with mesial temporal sclerosis (MTS) after single-stage anterior temporal lobectomy and amygdalohippocampectomy (ATL-AH). METHODS: The authors retrospectively reviewed 116 consecutive patients (66 females, mean age at surgery 40.7 years) with refractory seizures and pathologically confirmed MTS who underwent ATL-AH with at least 2 years of follow-up. All patients underwent preoperative MRI and video-electroencephalography (EEG); 106 patients (91.4%) underwent Wada testing and 107 patients (92.2%) had neuropsychological evaluations. The authors assessed the concordance of these 4 studies (defined as test consistent with the side of eventual surgery) and analyzed the impact of preoperative variables on seizure freedom. RESULTS: The median follow-up after surgery was 6.7 years (mean 6.9 years). Overall, 103 patients (89%) were seizure free, and 109 patients (94%) had Engel Class I or II outcome. Concordant findings were highest for video-EEG (100%), PET (100%), MRI (99.0%), and Wada testing (90.4%) and lowest for SPECT (84.6%) and neuropsychological testing (82.5%). Using binary logistic regression analysis (seizure free or not) and Cox proportional hazard analysis (seizure-free survival), less disparity in the Wada memory scores between the ipsilateral and contralateral sides was associated with persistent seizures. CONCLUSIONS: Seizure freedom of nearly 90% can be achieved with ATL-AH in properly selected patients with MTS and concordant preoperative studies. The low number of poor outcomes and exclusion of multistage patients limit the statistical power to determine preoperative variables that predict failure. Strong Wada memory lateralization was associated with excellent long-term outcome and adds important localization information to structural and neurophysiological data in predicting outcome after ATL-AH for MTS.

Is allograft sufficient for posterior atlantoaxial instrumented fusions with screw and rod constructs? A structured review of literature.

OBJECTIVE: Iliac crest autograft remains the gold standard for spinal fusion operations. Given risk of donor site morbidity, many centers utilize allograft. We reviewed published series of C1-2 posterolateral instrumented fusions with allograft and autograft. METHODS: Online databases were searched for English-language articles reporting quantifiable outcome data published between 1994 and 2011 of posterior atlantoaxial instrumented arthrodesis with C1 and C2 screws. Thirteen studies describing 652 patients having autograft and seven studies describing 60 patients having allograft serve as the basis of this report. RESULTS: All studies were retrospective case series (Class III evidence). There were no differences in complications or mortality between the groups. There were trends toward shorter operative times and less blood loss using allograft. A higher proportion of patients in the allograft group underwent sacrifice of the C2 nerve root and decortication and packing of the C1-2 joints (P<0.0001). There was no significant difference in the proportion of surviving patients who achieved solid fusion in the autograft (642 of 644 [99.7%]) and allograft patients (59 of 59 [100%]; P = 1.0). CONCLUSIONS: This review is limited by the retrospective data and inconsistent methodology of fusion determination used in most studies. Modern instrumentation and proper surgical techniques result in high rates of successful C1-2 arthrodesis. The use of allograft is a treatment option (Class III evidence) during posterior C1-2 instrumentation and fusion operations. Randomized, controlled trials using standardized radiographic assessments are needed across spinal arthrodesis studies to better determine the prevalence of radiographic fusion and establish technique superiority.

Comparison of safety and stability of C-2 pars and pedicle screws for atlantoaxial fusion: meta-analysis and review of the literature.

OBJECT: Some centers report a lower incidence of vertebral artery (VA) injury with C-2 pars screws compared with pedicle screws without sacrificing construct stability, despite biomechanical studies suggesting greater load failures with C-2 pedicle screws. The authors reviewed published series describing C-2 pars and pedicle screw implantation and atlantoaxial fusions and compared the incidence of VA injury, screw malposition, and successful atlantoaxial fusion with each screw type. METHODS: Online databases were searched for English-language articles between 1994 and April of 2011 describing the clinical and radiographic outcomes following posterior atlantoaxial fusion with C-1 lateral mass and either C-2 pars interarticularis or pedicle screws. Thirty-three studies describing 2975 C-2 pedicle screws and 11 studies describing 405 C-2 pars screws met inclusion criteria for the safety analysis. Seven studies describing 113 patients treated with C-2 pars screws and 20 studies describing 918 patients treated with C-2 pedicle screws met inclusion criteria for fusion analysis. Standard and formal meta-analysis techniques were used to compare outcomes. RESULTS: All studies provided Class III evidence. Ten instances of VA injury occurred with C-2 pedicle screws (0.3%) and no VA injury occurred with pars screws. The point estimate of VA injury for C-2 pedicle screws was 1.09% (95% CI 0.73%-1.63%) and was similar to that of C-2 pars screws (1.48%, 95% CI 0.62%-3.52%). Similarly, there was no statistically significant difference in the rate of clinically significant screw malpositions (1.14% [95% CI 0.77%-1.69%) vs 1.69% [95% CI 0.73%-3.84%]). Radiographically identified screw malposition occurred in a higher proportion of C-2 pedicle screws compared with C-2 pars screws (6.0% [95% CI 3.7%-9.6%] vs 4.0% [95% CI 2.0%-7.6%], p < 0.0001). Pseudarthrosis occurred in a greater proportion of patients treated with C-2 pars screws (5 [4.4%] of 113) compared with those treated with C-2 pedicle screws (2 [0.22%] of 900). Point estimates with 95% confidence intervals show a slightly higher rate of successful atlantoaxial fusion in the pedicle screw cohort (97.8% [CI 96.0%-98.8%] vs 93.5% [CI 86.6%-97.0%]; p < 0.0001). Q-testing ruled out heterogeneity between the study groups. CONCLUSIONS: With a thorough knowledge of axis anatomy, surgeons can place both C-2 pars and C-2 pedicle screws accurately with a small risk of VA injury or clinically significant malposition. There may be subtle trade-off of safety for rigidity when using axial pedicle instead of pars screws, and the decision to use either screw type must be made only after careful review of the preoperative CT imaging and must take into account the surgeon's expertise and the particular demands of the clinical scenario in any given case.