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Impact of body habitus on fluoroscopic radiation emission during minimally invasive spine surgery

Presented at the 2014 AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves

Sunil Kukreja, Justin Haydel, Anil Nanda and Anthony H. Sin


Minimally invasive spine surgeries (MISSs) have gained immense popularity in the last few years. Concern about the radiation exposure has also been raised. The purpose of this study was to demonstrate the impact of body habitus on the radiation emission during various MISS procedures. The authors also aim to evaluate the effect the surgeon's experience has on the amount of radiation exposure during MISS especially with regard to patient size.


The authors conducted a retrospective analysis of 332 patients who underwent 387 MISS procedures performed at their institution from January 2010 to August 2013 by a single surgeon. The dose of radiation emission available from the fluoroscopic equipment was recorded from the electronic database. The authors analyzed mainly 3 procedure groups: microdiscectomy/decompression (MiDD, n = 211) and transforaminal lumbar interbody fusion (TLIF) either with unilateral instrumentation (UnTLIF, n = 106) or bilateral instrumentation (BiTLIF, n = 70). The patients in each procedure group were divided into 6 categories based on the WHO criteria for obesity: underweight (body mass index [BMI] < 18.50), normal (18.50–24.99), overweight (25.00–29.99), Class 1 obese (30.00–34.99), Class 2 obese (35.00– 39.99), and Class 3 obese (> 40.00).


Patients who underwent BiTLIF had the highest median radiation exposure (113 mGy, SD 9.44), whereas microdiscectomy required minimal exposure (12.62 mGy, SD 2.75 mGy). There was a significant correlation between radiation emission and BMI of the patients during all MISS procedures (p < 0.05). The median radiation exposure was substantially greater with larger patients (p ≤ 0.001). In the analyses within the procedure groups, radiation exposure was found to be significantly high in patients who were severely obese (Class 2 and Class 3 obesity). The radiation emission was lower during the surgeries performed in 2013 than during those performed in 2010 especially in obese patients; however, this observation was not statistically significant.


Body habitus of the patients has a substantial impact on radiation emission during MISS. Severe obesity (BMI ≥ 35) is associated with a significantly greater risk of radiation exposure compared with other weight categories. Surgical experience seems to be associated with lower radiation emission especially in cases in which patients have a higher BMI; however, further studies should be performed to examine this effect.

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Sunil Kukreja, Sudheer Ambekar, Anthony Hunkyun Sin and Anil Nanda


Reports of myxopapillary ependymomas (MPEs) of the spinal cord in pediatric patients are scarce. In the literature, various authors have shared their experiences with small groups of patients, which makes it difficult to create a consensus regarding the treatment approach for spinal MPEs in young patients. The aim of this study was to perform a survival analysis of patients in the first 2 decades of life whose cases were selected from the published studies, and to examine the influence of various factors on outcomes.


A comprehensive search of studies published in English was performed on PubMed. Patients whose age was ≤ 20 years were included for integrative analysis. Information about age, treatment characteristics, critical events (progression, recurrence, and death), time to critical events, and follow-up duration was recorded. The degree of association of the various factors with the survival outcome was calculated by using Kaplan-Meier estimator and Cox proportional hazard model techniques.


A total of 95 patients were included in the analysis. The overall rate of recurrence (RR) was 34.7% (n = 33), with a median time to recurrence of 36 months (range 2–100 months). Progression-free survival (PFS) and overall survival rates at 5 years were 73.7% and 98.9%, respectively. Addition of radiotherapy (RT) following resection significantly improved PFS (log-rank test, p = 0.008). In patients who underwent subtotal resection (STR), administering RT (STR + RT) improved outcome with the lowest failure rates (10.3%), superior to patients who underwent gross-total resection (GTR) alone (RR 43.1%; log-rank test, p < 0.001). Addition of RT to patients who underwent GTR was not beneficial (log-rank test, p = 0.628). In patients who had disseminated tumor at presentation, adjuvant RT controlled the disease effectively. High-dose RT (≥ 50 Gy) did not change PFS (log-rank test, p = 0.710).


Routine inclusion of RT in the treatment protocol for spinal MPEs in young patients should be considered. Complete resection is always the goal of tumor resection. However, when complete resection does not seem to be possible in complex lesions, RT should be used as an adjunct to avoid aggressive resection and to minimize inadvertent injury to the surrounding neural tissues. High-dose RT (≥ 50 Gy) did not provide additional survival benefits, although this association needs to be evaluated by prospective studies.

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Anthony H. Sin, Gloria Caldito, Donald Smith, Mahmoud Rashidi, Brian Willis and Anil Nanda


A dural tear resulting in a cerebrospinal fluid (CSF) leak is a well-known risk of lumbar spinal procedures. The authors hypothesized that the incidence of CSF leakage is higher in cases involving repeated operations and those in which the surgeon performing the surgery is less experienced; however, they postulated that the overall outcome of the patient would not be adversely affected by a dural tear.


An institutional review board–approved protocol at Louisiana State University Health Sciences Center, Shreveport, was initiated in August 2003 to allow prospective comparison of data obtained in patients in whom a CSF leak occurred (Group A) and those in whom no CSF leak occurred (Group B) during lumbar surgery. Basic demographic information, descriptive findings regarding the tear, history of other surgeries, hospital length of stay (LOS), and immediate disposition at the time of discharge were compared between the two groups.

Seventy-seven patients were eligible for this study. One patient refused to participate. In 12 (15.8%) of 76 patients CSF leakage developed. In three patients the presence of a tear was questioned, and the patients were clinically treated as if a tear were present. The patients in Group A were older than those in Group B (59.8 ± 16.9 and 49.4 ± 13.6 years of age, respectively; p = 0.02, Fisher exact test). In terms of those with a history of surgery, there was no significant difference between patients with and patients without a CSF leak (three [25%] of 12 patients [Group A] compared with 28 [43.8%] of 64 patients [Group B]; p = 0.34, two-sample t-test). In the 12 patients with dural tears, nine (75%) were caused by a resident-in-training, and the Kerrison punch was the instrument most often being used at the time (55%). This is significantly greater than 50% at the 5% level (p = 0.044, binomial test). The authors were able to repair the tear primarily with suture in all but one patient, whose tear was along the nerve root sleeve. In all cases fibrin glue and a muscle/fat graft were used to cover the tear, and all patients were assigned to bed rest from 24 to 48 hours after the operation. In Group A one patient required rehabilitation at discharge. The LOS in Group A was greater than that in Group B (median 5 days compared with 3 days), but no additional complication was noted.


The incidence of CSF leakage was 16% in 76 patients, and there were no other complications. Older patient age and higher level of the surgeon’s training were factors contributing to the incidence, but the history of surgery was not.