Pennington, Zach

BACKGROUND AND OBJECTIVES: Ventriculoperitoneal shunt (VPS) placement is a common treatment for idiopathic normal pressure hydrocephalus (iNPH), but patients may require VPS revision. This study aims to evaluate the effectiveness of a standardized VPS placement protocol by comparing indications and rates of shunt revision compared with a historical institutional cohort. METHODS: All patients treated with VPS for “suspected” iNPH at a tertiary care center between January 2000 and January 2023 were retrospectively reviewed and divided into temporally distinct historical (before 2017) and standardized (after 2017) cohorts. Cumulative incidence and timing of VPS revision were compared using competing risks analyses. RESULTS: A total of 561 patients (median age 75.0 years) were identified with 324 (57.8%) in the historical and 237 (42.2%) in the standardized cohorts. Significant variations in surgical technique and shunt hardware were noted between the cohorts. With a median follow-up of 11.4 months for historical and 12.4 months for standardized cohort, shunt revisions occurred in 19.4% and 8.4% of patients in the historical and standardized cohorts, respectively ( P < .001). Revision indications also varied significantly with lower rates of overdrainage ( P < .001), infection ( P < .001), and proximal malfunction ( P = .042) but higher rate of distal malfunction ( P = .03) in the standardized cohort. Notably, no infections were noted in the standardized cohort. CONCLUSION: Risk of shunt revision among iNPH patients may be associated with modifiable factors related to surgical technique and shunt hardware selection. Importantly, no short-term complications such as hemorrhage, infection, or catheter malposition were observed with the standardized protocol. Development and refinement of standardized shunt protocols for iNPH patients should be commonplace to facilitate tracking, identification, and modification of modifiable technical risk factors.

BACKGROUND AND OBJECTIVES: The purpose of this study was to analyze the impact of patient-specific rods on mechanical complications after adult thoracolumbar spinal deformity surgery. METHODS: A consecutive series was analyzed of 200 adult thoracolumbar spinal deformity patients. Half of the patients (n = 100) had surgery just before implementing patient-specific rods, and the other 100 patients had surgery immediately after adoption of patient-specific rods. All patients had instrumented fusions from the thoracic spine to the pelvis. Mechanical complications were defined as rod fracture, proximal junctional kyphosis, proximal junctional failure (revision surgery requiring proximal fusion extension), and/or revision surgery for rod fracture or pseudoarthrosis. Minimum follow-up was 2 years. RESULTS: A total of 200 patients were included with a median (IQR) age of 68 (61, 73), body mass index of 28 (25, 32), and 73% were female. The patients with patient-specific rods compared with those without had less preoperative kyphosis (39° vs 44°, P = .01), a higher median number of rods (4 vs 2, P = .04), more often a combined anterior-posterior approach (61% vs 46%, P = .047), more commonly a upper instrumented vertebra vertebroplasty (67% vs 45% P = .003), and postoperatively had less thoracic kyphosis (45% vs 49%, P = .02). Patient-specific rod patients had a lower rate of mechanical complications (29% vs 47%, P = .01), a lower rate of rod fracture (3% vs 16%, P = .003), and shorter operative times (215 minutes vs 250 minutes, P = .04). On multivariable analysis, the only 2 independent predictors of reducing the rate of mechanical complications were the utilization of patient-specific rods (odds ratio 0.47, P = .013, CI 0.26-0.85) and lower postoperative thoracic kyphosis (odds ratio 1.02, P = .04, CI 1.00-1.05). CONCLUSION: In a consecutive series of adult thoracolumbar spinal deformity patients, patient-specific rods reduced the odds of mechanical complications by over 50%. Adoption of patient-specific rods should be considered to optimize patient outcomes after adult spinal deformity surgery.

Background: Anterior cervical discectomy and fusion (ACDF) is a widely performed procedure for treating degenerative cervical spine conditions. While it effectively addresses neural decompression and restores segmental alignment, the interplay of baseline alignment and implant-specific factors on postoperative segmental alignment remains underexplored. This study evaluates the influence of preoperative cervical alignment and interbody cage design on segmental alignment changes following 1- to 3-level ACDF. Methods: Following institutional review board approval, we identified 258 patients undergoing ACDF for degenerative pathology between 1 January 2010 and 31 December 2023. Preoperative and postoperative radiographs were analyzed for cervical alignment, disc height, and segmental lordosis. Cage dimensions, lordosis, and positioning relative to vertebral landmarks were recorded. Multivariable linear regression models evaluated predictors of postoperative disc height, segmental lordosis, and their respective changes. Results: Postoperative disc height was positively associated with greater cage height (β = 1.13 mm per mm, p < 0.001) and negatively associated with greater cage lordosis (β = −0.10 mm per °, p = 0.001). Segmental lordosis was positively influenced by cage height (β = 0.78° per mm, p = 0.002) and lordosis (β = 0.42° per °, p = 0.002) but was negatively correlated with the distance of the cage from the anterior edge of the cranial vertebra (β = −1.76° per mm, p = 0.004). Greater preoperative segmental kyphosis predicted more significant postoperative lordosis correction (β = −1.07° per °, p < 0.001). Conclusions: This study underscores the importance of preoperative alignment and interbody cage design in achieving optimal segmental correction following ACDF. While cage height primarily drives disc height restoration, surgical technique, particularly anterior placement of the cage, is pivotal for enhancing segmental lordosis. These findings support personalized surgical planning to optimize alignment and patient outcomes.

BACKGROUND AND OBJECTIVES: Stereotactic radiosurgery is a popular intervention for small vestibular schwannomas in patients with preserved hearing. Gamma Knife radiosurgery (GKRS) and CyberKnife radiosurgery (CKRS) represent 2 alternative modalities, with CKRS potentially allowing for the delivery of higher doses over multiple sessions. However, the optimal dosing and hearing outcomes of CKRS remain unclear. This study systematically reviewed all literature describing outcomes following treatment of vestibular schwannomas with CKRS, with a focus on tumor control, hearing preservation, and dosing schema. METHODS: The PubMed, Scopus, and Embase databases were queried to identify primary retrospective studies reporting local tumor control and hearing preservation rates following CKRS for vestibular schwannoma. Studies were reviewed, and the systematic review and meta-analysis were performed according to PRISMA and meta-analysis guidelines. RESULTS: Fifteen studies with study periods ranging from 1998 to 2018 were included. These studies comprised 2018 patients (mean age, 60.2 years; range, 11-91 years; 52% female), of whom 64 had neurofibromatosis type 2. The mean follow-up was 40 (range, 6-120) months, and 309 patients had undergone prior treatment (surgery and/or stereotactic radiosurgery). In aggregate, local control at the last follow-up was 96% (95% CI, 95%-98%), and 73% (95% CI, 66%-81%) of patients had preserved hearing. The most common major complications after CKRS were facial neuropathy (1.4%), trigeminal neuralgia (1.3%), and hydrocephalus (0.5%). CKRS provides a high rate of short-term and mid-term tumor control with hearing preservation comparable with GKRS, but long-term outcomes remain under investigated. CONCLUSION: This systematic review and meta-analysis found that CKRS offers high rates of tumor control and hearing preservation in patients undergoing stereotactic radiosurgery for vestibular schwannomas. Current data suggest that CKRS is a reasonable, safe therapeutic option for patients with small tumors and preserved hearing. Further exploration in larger cohorts and direct comparison with GKRS is merited.

BACKGROUND AND OBJECTIVES: Anterior lumbar interbody fusion (ALIF) is a powerful procedure for sagittal correction and indirect decompression in the lumbar spine, though aggressive correction can cause stretch neuropraxia and implant subsidence. The aim of this study was to identify radiographic and clinical predictors of segmental correction, as well as to evaluate the degree to which segmental correction on supine intraoperative radiographs translates to postoperative upright alignment changes. METHODS: We identified patients treated with 1- or 2-level ALIF at a tertiary care center and extracted data on demographics, spinopelvic parameters, and surgical details. Patients treated with isolated ALIF and ALIF with supplementary posterior instrumentation were compared on pre- and postoperative intradiscal lordosis (IDL) and change in IDL. Multivariable linear regression was performed to identify independent predictors of postoperative IDL. RESULTS: We included 204 patients (median age 57 years, 55.4% male) treated at 258 levels, of whom 114 (55.9%) underwent supplementary posterior fixation and 150 (73.5%) underwent single-level implantation. Across all patients, postoperative IDL was significantly greater than preoperative segmental lordosis (25.4° vs 15.3°; P < .001). Standalone ALIF achieved less ΔIDL than circumferential fusion for L5/S1 procedures (7.4° vs 11.6°; P < .001), though ΔIDL for L3/4 and L4/5 was similar between the standalone and circumferential groups. Multivariable analysis showed postoperative IDL to be predicted by greater preoperative IDL (β = 0.26° per degree; [0.15, 0.36]; P < .001), L5/S1 [vs L4/5] implantation (β = 3.97°; [2.72, 5.21]; P < .001), use of supplementary posterior fixation (β = 1.80°; [0.70, 2.89]; P < .001), and greater implant lordosis (β = 0.62° per degree; [0.44, 0.79]; P < .001). CONCLUSION: Postoperative IDL after 1- or 2-level ALIF is best predicted by placement of larger interbody sizes, L5/S1 implantation, greater baseline IDL, and use of adjunct posterior fixation. Patients with higher preoperative lordosis experienced smaller postoperative increases in IDL, though this was likely influenced by a treatment bias.