Real-time navigation guidance with intraoperative CT imaging for pedicle screw placement using an augmented reality head-mounted display: a proof-of-concept study.

OBJECTIVE: Augmented reality (AR) has the potential to improve the accuracy and efficiency of instrumentation placement in spinal fusion surgery, increasing patient safety and outcomes, optimizing ergonomics in the surgical suite, and ultimately lowering procedural costs. The authors sought to describe the use of a commercial prototype Spine AR platform (SpineAR) that provides a commercial AR head-mounted display (ARHMD) user interface for navigation-guided spine surgery incorporating real-time navigation images from intraoperative imaging with a 3D-reconstructed model in the surgeon's field of view, and to assess screw placement accuracy via this method. METHODS: Pedicle screw placement accuracy was assessed and compared with literature-reported data of the freehand (FH) technique. Accuracy with SpineAR was also compared between participants of varying spine surgical experience. Eleven operators without prior experience with AR-assisted pedicle screw placement took part in the study: 5 attending neurosurgeons and 6 trainees (1 neurosurgical fellow, 1 senior orthopedic resident, 3 neurosurgical residents, and 1 medical student). Commercially available 3D-printed lumbar spine models were utilized as surrogates of human anatomy. Among the operators, a total of 192 screws were instrumented bilaterally from L2-5 using SpineAR in 24 lumbar spine models. All but one trainee also inserted 8 screws using the FH method. In addition to accuracy scoring using the Gertzbein-Robbins grading scale, axial trajectory was assessed, and user feedback on experience with SpineAR was collected. RESULTS: Based on the Gertzbein-Robbins grading scale, the overall screw placement accuracy using SpineAR among all users was 98.4% (192 screws). Accuracy for attendings and trainees was 99.1% (112 screws) and 97.5% (80 screws), respectively. Accuracy rates were higher compared with literature-reported lumbar screw placement accuracy using FH for attendings (99.1% vs 94.32%; p = 0.0212) and all users (98.4% vs 94.32%; p = 0.0099). The percentage of total inserted screws with a minimum of 5° medial angulation was 100%. No differences were observed between attendings and trainees or between the two methods. User feedback on SpineAR was generally positive. CONCLUSIONS: Screw placement was feasible and accurate using SpineAR, an ARHMD platform with real-time navigation guidance that provided a favorable surgeon-user experience.

Increased frequency of cataract surgery in patients over age 50 with pituitary macroadenomas and chiasmal compression.

BACKGROUND: Patients with visual loss from macroadenomas compressing their optic apparatus may also have concomitant age-related visual pathology such as cataracts. How these two pathologies interact with each other is not well documented. OBJECTIVE: The interaction between these two pathologies in elderly patients is the subject of this study. METHODS: We identified a series of non-functioning macroadenoma patients over age 50 years with tumors compressing the chiasm who underwent transsphenoidal surgery at our institution between 2004 and 2018. Pre- and post-operative visual complaints, tumor size and extent of resection were analyzed. Prevalence of the diagnosis of cataract and prevalence of cataract surgery in each decade were compared with national averages. RESULTS: We identified 200 patients who met selection criteria. 18% of these patients had a diagnosis of cataract and 12.5% had cataract surgery. Compared with the Eye Diseases Prevalence Research Group (EDPRG) study, the prevalence of cataract surgery was 2.5 times the national average of 5.1%. 32% of these patients had no improvement in their vision after cataract surgery but 76% improved after transsphenoidal surgery. CONCLUSIONS: We reported a high prevalence of cataract surgery in patients over age 50 in patients with pituitary macroadenomas compressing the optic pathway compared with national averages in patients without adenomas. While visual loss from adenoma likely precipitated more cataract surgeries in this group of patients, some who may not have required it, those patients with cataracts who did not have their cataracts extracted were less likely to recover vision after transsphenoidal surgery. Addressing both pathologies is beneficial.

Endonasal surgery for suprasellar germ cell tumors: two cases and review of the literature.

Germ cell tumors are rare malignant tumors frequently located in the suprasellar region. Definitive treatment is chemotherapy and radiation. However, in some circumstances, surgery is indicated for biopsy or resection. There are limited reports of the role of the endonasal endoscopic approach (EEA) in the management of this tumor. We present two cases in which EEA was utilized for successful management of germ cell tumor. The most challenging aspect of germ cell tumor management for the treating physician is knowing the proper indications for surgery. In this paper, we highlight two specific instances, namely diagnosis and tumor refractory to chemoradiation. Given the suprasellar location, EEA is an ideal approach.

Moderate hypothermia for intradural spinal tumor resection: a cohort comparison and feasibility study.

To evaluate the safety and feasibility of modest hypothermia as a potential strategy for intraoperative neuroprotection during the removal of intradural spinal tumors. A retrospective review was performed for two groups of patients of a single surgeon who underwent intradural extrameduallary and intramedullary spinal tumor resection of tumors located between cervical level 1 and lumbar 2 over a 10-year period between 2001 and 2010. One cohort received intraoperative moderate hypothermia (33°C) via intravascular catheter cooling during tumor surgery and the second cohort, a historical control group of the same surgeon, underwent surgery at normothermia (≥36°C). The main outcome measured was safety as determined by surgical, medical, and neurological complications. The hypothermia (n=38) and nonhypothermia (n=34) groups were homogenous for patient demographics and baseline comorbidities. There were no differences between the groups regarding tumor level (p=0.51), tumor pathology, or intramedullary versus intradural extramedullary location (p=0.11). The hypothermia group had a lower mean body temperature (33.7°C±0.72 vs. 36.6°C±0.7, p≤0.001) longer postoperative hospital stays (10.8±14.0 vs. 7.3±4.72, p<0.001), but there were no significant differences in operative and perioperative variables such as, total anesthetic time (8.2±2.4 vs. 7.8±2.7 hours, p=0.45), total surgical time (5.9±2.1 vs. 5.7±2.5 hours, p=0.58), or estimated blood loss (483±420 vs. 420±314 mL, p=0.65). There were no statistically significant differences between the two groups with respect to the rate of surgical (3 vs. 2, p=1.0), medical (4 vs. 3, p=1.0), neurological (3 vs. 4, p=0.7), or overall complications (10 vs. 9, p=1.0). In this study, moderate hypothermia via intravascular cooling catheters was successfully performed during 38 intradural spinal tumor surgeries. Compared to the historical control group, the hypothermia patients had longer hospital stays, but did not have higher complication rates. Intraoperative moderate hypothermia during spinal tumor resection is feasible and appeared safe in this limited cohort; however, further studies with larger cohorts will be needed to determine whether peri-operative hypothermia is an effective neuroprotectant strategy in spinal tumor surgery.

A comparison of acute hospital charges after tubular versus open microdiskectomy.

OBJECTIVE: To determine if tubular microdiskectomy is associated with differences in hospital charges compared with open microdiskectomy. METHODS: A retrospective review of patients who underwent tubular microdiskectomy or open microdiskectomy performed by the senior authors from 2007-2010 was performed. The primary outcome was inflation-adjusted total hospital charges for each procedure using itemized charge data obtained from the hospital finance department. Secondary outcomes included length of stay, complications, and operative times. RESULTS: There were 76 eligible patients (33 open microdiskectomy and 48 tubular microdiskectomy) identified during the study period. The mean total charge was $27,811 (standard deviation $11,198) in the open group compared with $22,358 (standard deviation $8695) in the tubular group. Total charges in the tubular group were on average $5453 less than in the open group (P = 0.02). There were no significant differences in operative times or complications. Length of stay was significantly shorter in the tubular group (mean 1.5 days open vs. 0.9 days tubular, P = 0.01). CONCLUSIONS: This analysis revealed significantly lower acute hospital charges associated with tubular microdiskectomy versus open microdiskectomy at an academic tertiary care hospital. These differences appear to the related to decreased use of postoperative resources in the tubular group.

An analysis of postoperative thigh symptoms after minimally invasive transpsoas lumbar interbody fusion.

OBJECTIVE: The minimally invasive transpsoas interbody fusion technique requires dissection through the psoas muscle, which contains the nerves of the lumbosacral plexus posteriorly and genitofemoral nerve anteriorly. Retraction of the psoas is becoming recognized as a cause of transient postoperative thigh pain, numbness, paresthesias, and weakness. However, few reports have described the nature of thigh symptoms after this procedure. METHODS: The authors performed a review of patients who underwent the transpsoas technique for lumbar spondylotic disease, disc degeneration, and spondylolisthesis treated at a single academic medical center. A review of patient charts, including the use of detailed patient-driven pain diagrams performed at equal preoperative and follow-up intervals, investigated the survival of postoperative thigh pain, numbness, paresthesias, and weakness of the iliopsoas and quadriceps muscles in the follow-up period on the ipsilateral side of the surgical approach. RESULTS: Over a 3.2-year period, 59 patients underwent transpsoas interbody fusion surgery. Of these, 62.7% had thigh symptoms postoperatively. New thigh symptoms at first follow-up visit included the following: burning, aching, stabbing, or other pain (39.0%); numbness (42.4%); paresthesias (11.9%); and weakness (23.7%). At 3 months postoperatively, these percentages decreased to 15.5%, 24.1%, 5.6%, and 11.3%, respectively. Within the patient sample, 44% underwent a 1-level, 41% a 2-level, and 15% a 3-level transpsoas operation. While not statistically significant, thigh pain, numbness, and weakness were most prevalent after L4-5 transpsoas interbody fusion at the first postoperative follow-up. The number of lumbar levels that were surgically treated had no clear association with thigh symptoms but did correlate directly with surgical time, intraoperative blood loss, and length of hospital stay. CONCLUSIONS: Transpsoas interbody fusion is associated with high rates of immediate postoperative thigh symptoms. While larger, prospective studies are necessary to validate these findings, the authors found that half of the patients had symptom resolution at approximately 3 months postoperatively and more than 90% by 1 year.

An analysis of the differences in the acute hospitalization charges following minimally invasive versus open posterior lumbar interbody fusion.

OBJECT: Minimally invasive spine (MIS) procedures are increasingly being recognized as equivalent to open procedures with regard to clinical and radiographic outcomes. These techniques are also believed to result in less pain and disability in the immediate postoperative period. There are, however, little data to assess whether these procedures produce their intended result and even fewer objective data to demonstrate that they are cost effective when compared with open surgery. METHODS: The authors performed a retrospective analysis of hospital charges for 1- and 2-level MIS and open posterior interbody fusion for lumbar spondylotic disease, disc degeneration, and spondylolisthesis treated at a single academic medical center. Patients presenting with bilateral neurological symptoms were treated with open surgery, and those with unilateral symptoms were treated with MIS. Overall hospital charges and surgical episode-related charges, length of stay (LOS), and discharge status were obtained from the hospital finance department and adjusted for multi-/single-level surgeries. RESULTS: During a 14-month period, 74 patients (mean age 55 years) were treated. The series included 59 single-level operations (75% MIS and 25% open), and 15 2-level surgeries (53% MIS and 47% open). The demographic profile, including age and Charlson Comorbidity Index, were similar between the 4 groups. The mean LOS for patients undergoing single-level surgery was 3.9 and 4.8 days in the MIS and open cases, respectively (p = 0.017). For those undergoing 2-level surgery, the mean LOS was 5.1 for MIS versus 7.1 for open surgery (p = 0.259). With respect to hospital charges, single-level MIS procedures were associated with an average of $70,159 compared with $78,444 for open surgery (p = 0.027). For 2-level surgery, mean charges totalled $87,454 for MIS versus $108,843 for open surgery (p = 0.071). For single-level surgeries, 5 and 20% of patients undergoing MIS and open surgery, respectively, were discharged to inpatient rehabilitation. For 2-level surgeries, the rates were 13 and 29%, respectively. CONCLUSIONS: While hospital setting, treatment population, patient selection, and physician expectation play major roles in determining hospital charges and LOS, this pilot study at an academic teaching hospital shows trends for quicker discharge, reduced hospital charges, and lower transfer rates to inpatient rehabilitation with MIS. However, larger multicenter studies are necessary to validate these findings and their relevance across diverse US practice environments.