Search Results

You are looking at 1 - 10 of 22 items for

  • Author or Editor: Ann Liu x
  • Refine by Access: all x
Clear All Modify Search
Restricted access

The metopic index: an anthropometric index for the quantitative assessment of trigonocephaly from metopic synostosis

Joanna Y. Wang, Amir H. Dorafshar, Ann Liu, Mari L. Groves, and Edward S. Ahn

OBJECTIVE

Because the metopic suture normally fuses during infancy, there are varying degrees of severity in head shape abnormalities associated with premature fusion. A method for the objective and reproducible assessment of metopic synostosis is needed to guide management, as current methods are limited by their reliance on aesthetic markers. The object of this study was to describe the metopic index (MI), a simple anthropometric cranial measurement. The measurements can be obtained from CT scans and, more importantly, from palpable cranial landmarks, and the index provides a rapid tool for evaluating patients in both pre- and postoperative settings.

METHODS

High-resolution head CT scans obtained in 69 patients (age range 0–24 months) diagnosed with metopic craniosynostosis were retrospectively reviewed. Preoperative 3D reconstructions were available in 15 cases, and these were compared with 3D reconstructions of 324 CT scans obtained in a control group of 316 infants (age range 0–24 months) who did not have any condition that might affect head size or shape and also in a subset of this group, comprising 112 patients precisely matched to the craniosynostosis patients with respect to age and sex. Postoperative scans were available and reviewed in 9 of the craniosynostosis patients at a mean time of 7.1 months after surgical repair. 3D reconstructions of these scans were matched with controls based upon age and sex.

RESULTS

The mean preoperative MI for patients with trigonocephaly was 0.48 (SD 0.05), significantly lower than the mean values of 0.57 (SD 0.04) calculated on the basis of all 324 scans obtained in controls (p < 0.001) and 0.58 (SD 0.04) for the subset of 112 age- and sex-matched controls (p < 0.001). For 7 patients with both pre- and postoperative CT scans available for evaluation, the mean postoperative MI was 0.55 (SD 0.03), significantly greater than their preoperative MIs (mean 0.48 [SD 0.04], p = 0.001) and comparable to the mean MI of the controls (p = 0.30). In 4 patients, clinically obtained postoperative MIs by caliper measurement were comparable to measurements derived from CT (p = 0.141).

CONCLUSIONS

The MI is a useful measurement of the severity of trigonocephaly in patients with metopic synostosis. This simple quantitative assessment can potentially be used in the clinical setting to guide preoperative evaluation, surgical repair, and postoperative degree of correction.

Open access

Robot-assisted atlantoaxial fixation: illustrative cases

Amanda N. Sacino, Joshua Materi, A. Daniel Davidar, Brendan Judy, Ann Liu, Brian Hwang, and Nicholas Theodore

BACKGROUND

Placing screws in the high cervical spine can be challenging because of the vital anatomical structures located in that region. Precision and accuracy with screw placement is needed. The use of robotics in the cervical spine has been described before; however, here the authors describe the use of a new robotic setup.

OBSERVATIONS

The authors describe 2 cases of robot-assisted placement of C2 pars screws and C1–2 transarticular screws. The operative plans for each patient were as follows: placement of C2 pars screws with C2–4 fusion for hangman’s fracture and placement of C1–2 transarticular screws for degenerative disease. Intraoperative computed tomography (CT) was used to plan and navigate the screws. Postoperative CT showed excellent placement of hardware. Both patients presented for initial postoperative clinic visits with no recurrence of prior symptoms.

LESSONS

Intraoperative robotic assistance with instrumentation of the high cervical spine, particularly C2 pars and C1–2 transarticular screws, may ensure proper screw placement and help avoid injury.

Free access

Letter to the Editor. Pedicle screw placement: head-mounted display-based augmented reality for better precision

Ebtesam Abdulla, Sabrina Rahman, and Md Moshiur Rahman

Free access

Editorial. Navigation in spine surgery: an innovation here to stay

Joseph Driver and Michael W. Groff

Free access

Letter to the Editor. Augmented reality–assisted spinal instrumentation placement

Tadatsugu Morimoto, Takaomi Kobayashi, Masaya Ueno, Hirohito Hirata, and Masaaki Mawatari

Free access

Novel placement of cortical bone trajectory screws in previously instrumented pedicles for adjacent-segment lumbar disease using CT image-guided navigation

Technical note

Analiz Rodriguez, Matthew T. Neal, Ann Liu, Aravind Somasundaram, Wesley Hsu, and Charles L. Branch Jr

Object

Symptomatic adjacent-segment lumbar disease (ASLD) after lumbar fusion often requires subsequent surgical intervention. The authors report utilizing cortical bone trajectory (CBT) pedicle screw fixation with intraoperative CT (O-arm) image-guided navigation to stabilize spinal levels in patients with symptomatic ASLD. This unique technique results in the placement of 2 screws in the same pedicle (1 traditional pedicle trajectory and 1 CBT) and obviates the need to remove preexisting instrumentation.

Methods

The records of 5 consecutive patients who underwent lumbar spinal fusion with CBT and posterior interbody grafting for ASLD were retrospectively reviewed. All patients underwent screw trajectory planning with the O-arm in conjunction with the StealthStation navigation system. Basic demographics, operative details, and radiographic and clinical outcomes were obtained.

Results

The average patient age was 69.4 years (range 58–82 years). Four of the 5 surgeries were performed with the Minimal Access Spinal Technologies (MAST) Midline Lumbar Fusion (MIDLF) system. The average operative duration was 218 minutes (range 175–315 minutes). In the entire cohort, 5.5-mm cortical screws were placed in previously instrumented pedicles. The average hospital stay was 2.8 days (range 2–3 days) and there were no surgical complications. All patients had more than 6 months of radiographic and clinical follow-up (range 10–15 months). At last follow-up, all patients reported improved symptoms from their preoperative state. Radiographic follow-up showed Lenke fusion grades of A or B.

Conclusions

The authors present a novel fusion technique that uses CBT pedicle screw fixation in a previously instrumented pedicle with intraoperative O-arm guided navigation. This method obviates the need for hardware removal. This cohort of patients experienced good clinical results. Computed tomography navigation was critical for accurate CBT screw placement at levels where previous traditional pedicle screws were already placed for symptomatic ASLD.

Free access

Instrumented fusion for spinal deformity after laminectomy or laminoplasty for resection of intramedullary spinal cord tumors in pediatric patients

David S. Hersh, Rajiv R. Iyer, Tomas Garzon-Muvdi, Ann Liu, George I. Jallo, and Mari L. Groves

OBJECTIVE

Spinal deformity has become a well-recognized complication of intramedullary spinal cord tumor (IMSCT) resection. In particular, laminectomy can result in biomechanical instability caused by loss of the posterior tension band. Therefore, laminoplasty has been proposed as an alternative to laminectomy. Here, the authors describe the largest current series of pediatric patients who have undergone laminoplasty for IMSCT resection and investigate the need for surgical fusion after both laminectomy and laminoplasty.

METHODS

The medical records of pediatric patients who underwent resection of an IMSCT at a single institution between November 2003 and May 2014 were reviewed retrospectively. Demographic, clinical, radiological, surgical, histopathological, and follow-up data were collected.

RESULTS

Sixty-six consecutive patients underwent resection of an IMSCT during the study period. Forty-three (65%) patients were male. The patients had a median age of 12.9 years (interquartile range [IQR] 7.2–16.5 years) at the time of surgery. Patients typically presented with a tumor that involved the cervical and/or thoracic spine. Nineteen (29%) patients underwent laminectomy, and 47 (71%) patients underwent laminoplasty. Patients in each cohort had a similar rate of postoperative deformity. Overall, 10 (15%) patients required instrumented spinal fusion for spinal deformity. Four patients required revision of the primary fusion.

CONCLUSIONS

These findings show that among pediatric patients with an IMSCT, postoperative surgical fusion rates remain high, even after laminoplasty. Known risk factors, such as the age of the patient, location of the tumor, and the number of involved levels, might play a larger role than replacement of the laminae in determining the rate of surgical fusion after IMSCT resection.

Restricted access

Gamma Knife radiosurgery for meningiomas in patients with neurofibromatosis Type 2

Ann Liu, Elizabeth N. Kuhn, John T. Lucas Jr., Adrian W. Laxton, Stephen B. Tatter, and Michael D. Chan

OBJECT

Neurofibromatosis Type 2 (NF2) is a rare autosomal dominant disorder predisposing patients to meningiomatosis. The role of stereotactic radiosurgery (SRS) is poorly defined in NF2, and although the procedure has excellent control rates in the non-NF2 population, its utility has been questioned because radiation has been hypothesized to predispose patients to malignant transformation of benign tumors. To the authors' knowledge, this is the first study to examine the use of SRS specifically for meningiomas in patients with NF2.

METHODS

The authors searched a tumor registry for all patients with NF2 who had undergone Gamma Knife radiosurgery (GKRS) for meningioma in the period from January 1, 1999, to September 19, 2013, at a single tertiary care cancer center. Medical records were retrospectively reviewed for patient and tumor characteristics and outcomes.

Results

Among the 12 patients who met the search criteria, 125 meningiomas were identified, 87 (70%) of which were symptomatic or progressive and thus treated with GKRS. The median age at the first GKRS was 31 years (interquartile range [IQR] 27–37 years). Five patients (42%) had multiple treatments with a median of 27 months (IQR 14–50 months) until the subsequent GKRS. The median follow-up in surviving patients was 43 months (IQR 34–110 months). The 5-year local tumor control and distant treatment failure rates were 92% and 77%, respectively. Toxicities occurred in 25% of the GKRS treatments, although the majority were Grade 1 or 2. At the last follow-up, 4 patients (33%) had died a neurological death at a median age of 39 years (IQR 37–46 years), and their cases accounted for 45% of all tumors, 55% of all treated tumors, and 58% of all GKRSs. Univariate analysis revealed several predictive variables for distant failure, including male sex (HR 0.28, 95% CI 0.086–0.92, p = 0.036), age at distant failure (HR 0.92, 95% CI 0.90–0.95, p < 0.0001), and prior number of GKRS treatments (HR 1.2, 95% CI 1.1–1.4, p = 0.0049). Local failure, maximum size of the treated tumor, delivered tumor margin dose, and WHO grade were not significant. On multivariate analysis, age at distant failure (HR 0.91, 95% CI 0.88–0.95, p < 0.0001) and prior number of GKRSs (HR 1.3, 95% CI 1.1–1.5, p = 0.004) remained significant. No malignant transformation events among treated tumors were observed.

CONCLUSIONS

Radiosurgery represents a feasible modality with minimal toxicity for NF2-associated meningiomas. Increasing patient age was associated with a decreased rate of distant failure, whereas an increasing number of prior GKRS treatments predicted distant failure. Further studies are necessary to determine the long-term patterns of treatment failure in these patients.

Restricted access

Predictors of admission and shunt revision during emergency department visits for shunt-treated adult patients with idiopathic intracranial hypertension

Eric W. Sankey, Benjamin D. Elder, Ann Liu, Kathryn A. Carson, C. Rory Goodwin, Ignacio Jusué-Torres, and Daniele Rigamonti

OBJECTIVE

Factors associated with emergency department admission and/or shunt revision for idiopathic intracranial hypertension (IIH) are unclear. In this study, the associations of several factors with emergency department admission and shunt revision for IIH were explored.

METHODS

The authors performed a retrospective review of 31 patients (169 total emergency department visits) who presented to the emergency department for IIH-related symptoms between 2003 and 2015. Demographics, comorbidities, symptoms, IIH diagnosis and treatment history, ophthalmological examination, diagnostic lumbar puncture (LP), imaging findings, and data regarding admission and management decisions were collected. Multivariable general linear models regression analysis was performed to assess the predictive factors associated with admission and shunt revision.

RESULTS

Thirty-one adult patients with a history of shunt placement for IIH visited the emergency department a total of 169 times for IIH-related symptoms, with a median of 3 visits (interquartile range 2–7 visits) per patient. Five patients had more than 10 emergency department visits. Baseline factors associated with admission included male sex (OR 10.47, 95% CI 2.13–51.56; p = 0.004) and performance of an LP (OR 3.10, 95% CI 1.31–7.31; p = 0.01). Contrastingly, older age at presentation (OR 0.94, 95% CI 0.90–0.99; p = 0.01), and a greater number of prior emergency department visits (OR 0.94, 95% CI 0.89–0.99; p = 0.02) were slightly protective against admission. The presence of papilledema (OR 11.62, 95% CI 3.20–42.16; p < 0.001), Caucasian race (OR 40.53, 95% CI 2.49–660.09 p = 0.009), and systemic hypertension (OR 7.73, 95% CI 1.11–53.62; p = 0.03) were independent risk factors for shunt revision. In addition, a greater number of prior emergency department visits (OR 0.86, 95% CI 0.77–0.96; p = 0.009) and older age at presentation (OR 0.93, 95% CI 0.87–0.99; p = 0.02) were slightly protective against shunt revision, while there was suggestive evidence that presence of a programmable shunt (OR 0.23, 95% CI 0.05–1.14; p = 0.07) was a protective factor against shunt revision. Of note, location of the proximal catheter in the ventricle or lumbar subarachnoid space was not significantly associated with admission or shunt revision in the multivariable analyses.

CONCLUSIONS

The decision to admit a shunt-treated patient from the emergency department for symptoms related to IIH is challenging. Knowledge of factors associated with the need for admission and/or shunt revision is required. In this study, factors such as male sex, younger age at presentation, lower number of prior emergency department visits, and performance of a diagnostic LP were independent predictors of admission. In addition, papilledema was strongly predictive of the need for shunt revision, highlighting the importance of an ophthalmological examination for shunt-treated adults with IIH who present to the emergency department.

Restricted access

Positive trends in neurosurgery enrollment and attrition: analysis of the 2000–2009 female neurosurgery resident cohort

Jaclyn J. Renfrow, Analiz Rodriguez, Ann Liu, Julie G. Pilitsis, Uzma Samadani, Aruna Ganju, Isabelle M. Germano, Deborah L. Benzil, and Stacey Quintero Wolfe

OBJECT

Women compose a minority of neurosurgery residents, averaging just over 10% of matched applicants per year during this decade. A recent review by Lynch et al. raises the concern that women may be at a higher risk than men for attrition, based on analysis of a cohort matched between 1990 and 1999. This manuscript aims to characterize the trends in enrollment, attrition, and postattrition careers for women who matched in neurosurgery between 2000 and 2009.

METHODS

Databases from the American Association of Neurological Surgeons (AANS) and the American Board of Neurological Surgery (ABNS) were analyzed for all residents who matched into neurosurgery during the years 2000–2009. Residents were sorted by female gender, matched against graduation records, and if graduation was not reported from neurosurgery residency programs, an Internet search was used to determine the residents’ alternative path. The primary outcome was to determine the number of women residents who did not complete neurosurgery training programs during 2000–2009. Secondary outcomes included the total number of women who matched into neurosurgery per year, year in training in which attrition occurred, and alternative career paths that these women chose to pursue.

RESULTS

Women comprised 240 of 1992 (12%) matched neurosurgery residents during 2000–2009. Among female residents there was a 17% attrition rate, compared with a 5.3% male attrition rate, with an overall attrition rate of 6.7%. The majority who left the field did so within the first 3 years of neurosurgical training and stayed in medicine—pursuing anesthesia, neurology, and radiology.

CONCLUSIONS

Although the percentage of women entering neurosurgical residency has continued to increase, this number is still disproportionate to the overall number of women in medicine. The female attrition rate in neurosurgery in the 2000–2009 cohort is comparable to that of the other surgical specialties, but for neurosurgery, there is disparity between the male and female attrition rates. Women who left the field tended to stay within medicine and usually pursued a neuroscience-related career. Given the need for talented women to pursue neurosurgery and the increasing numbers of women matching annually, the recruitment and retention of women in neurosurgery should be benchmarked and assessed.