Subhas K. Konar, Shyamal C. Bir, Tanmoy K. Maiti, Papireddy Bollam and Anil Nanda
Isadore Max Tarlov, an early neurosurgeon, made several important contributions to the field of spine surgery. He described sacral perineural cysts, now known as Tarlov cysts. Dr. Tarlov also introduced the knee-chest patient position to facilitate exposure and hemostasis in lumbar surgery. In addition, he developed the use of fibrin glue in nerve repair. His book on mechanisms of spinal compression was published in 1957. He published a book of essays titled Principles of Parsimony in Medical Practice that remains highly relevant in today's medical world.
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.
Sunil Kukreja, Sudheer Ambekar, Mayur Sharma and Anil Nanda
The authors report the case of a spinal intradural schwannoma presenting with intracranial subarachnoid hemorrhage (SAH). Cerebral angiography did not show any intracranial lesion; however, MRI revealed two separate tumors in the lower segment of the spinal cord. The proximal lesion arising from the conus medullaris was well circumscribed and homogeneously enhanced, whereas the tumor in the cauda equina revealed hemorrhagic signals on MRI. This case also illustrates an unusual presentation of intracranial SAH simultaneously with intratumoral hemorrhage in a spinal cord schwannoma. The absence of hemorrhagic changes in the lesion arising proximal to the cauda equina region supports the mechanical theory proposed for the pathogenesis of hemorrhagic complications in spinal cord tumors.
Mayur Sharma, Ashish Sonig, Sudheer Ambekar and Anil Nanda
The aim of this study was to analyze the incidence of adverse outcomes and inpatient mortality following resection of intramedullary spinal cord tumors by using the US Nationwide Inpatient Sample (NIS) database. The overall complication rate, length of the hospital stay, and the total cost of hospitalization were also analyzed from the database.
This is a retrospective cohort study conducted using the NIS data from 2003 to 2010. Various patient-related (demographic categories, complications, comorbidities, and median household income) and hospital-related variables (number of beds, high/low case volume, rural/urban location, region, ownership, and teaching status) were analyzed from the database. The adverse discharge disposition, in-hospital mortality, and the higher cost of hospitalization were taken as the dependent variables.
A total of 15,545 admissions were identified from the NIS database. The mean patient age was 44.84 ± 19.49 years (mean ± SD), and 7938 (52%) of the patients were male. Regarding discharge disposition, 64.1% (n = 9917) of the patients were discharged to home or self-care, and the overall in-hospital mortality rate was 0.46% (n = 71). The mean total charges for hospitalization increased from $45,452.24 in 2003 to $76,698.96 in 2010. Elderly patients, female sex, black race, and lower income based on ZIP code were the independent predictors of other than routine (OTR) disposition (p < 0.001). Private insurance showed a protective effect against OTR disposition. Patients with a higher comorbidity index (OR 1.908, 95% CI 1.733–2.101; p < 0.001) and with complications (OR 2.214, 95% CI 1.768–2.772; p < 0.001) were more likely to have an adverse discharge disposition. Hospitals with a larger number of beds and those in the Northeast region were independent predictors of the OTR discharge disposition (p < 0.001). Admissions on weekends and nonelective admission had significant influence on the disposition (p < 0.001). Weekend and nonelective admissions were found to be independent predictors of inpatient mortality and the higher cost incurred to the hospitals (p < 0.001). High-volume and large hospitals, West region, and teaching hospitals were also the predictors of higher cost incurred to the hospitals (p < 0.001). The following variables (young patients, higher median household income, nonprivate insurance, presence of complications, and a higher comorbidity index) were significantly correlated with higher hospital charges (p < 0.001), whereas the variables young patients, nonprivate insurance, higher median household income, and higher comorbidity index independently predicted for inpatient mortality (p < 0.001).
The independent predictors of adverse discharge disposition were as follows: elderly patients, female sex, black race, lower median household income, nonprivate insurance, higher comorbidity index, presence of complications, larger hospital size, Northeast region, and weekend and nonelective admissions. The predictors of higher cost incurred to the hospitals were as follows: young patients, higher median household income, nonprivate insurance, presence of complications, higher comorbidity index, hospitals with high volume and a large number of beds, West region, teaching hospitals, and weekend and nonelective admissions.
David E. Connor Jr., Prashant Chittiboina, Gloria Caldito and Anil Nanda
Spinal epidural abscess (SEA), once considered a rare occurrence, has showed a rapid increase in incidence over the past 20–30 years. Recent reports have advocated for conservative, nonoperative management of this devastating disorder with appropriate risk stratification. Crucial to a successful management strategy are decisive diagnosis, prompt intervention, and consistent follow-up care. The authors present a review of their institutional experience with operative and nonoperative management of SEA to assess morbidity and mortality and the accuracy of microbiological diagnosis.
A retrospective analysis of patient charts, microbiology reports, operative records, and radiology reports was performed on all cases involving patients admitted with the diagnosis of SEA between July 1998 and May 2009.
Seventy-seven cases were reviewed (median patient age 51.4 years, range 17–78 years). Axial pain was the most common presenting symptom (67.5% of cases). Presenting signs included focal weakness (55.8%), radiculopathy (28.6%), and myelopathy (5.2%). Abscesses were localized to the lumbar, thoracic, and cervical spine, respectively, in 39 (50.6%), 20 (26.0%), and 18 (23.4%) of the patients. Peripheral blood cultures were negative in 32 (45.1%) of 71 patients. Surgical site or interventional biopsy cultures were diagnostic in 52 cases (78.8%), with concordant blood culture results in 36 (60.0%). Methicillin-resistant Staphylococcus aureus (MRSA) was the most frequent isolate in 24 cases (31.2%). The mean time from admission to surgery was 5.5 days (range 0–42 days; within 72 hours in 66.7% of cases). Outcome data were available in 72 cases. At discharge, patient condition had improved or resolved in 57 cases (79.2%), improved minimally in 6 (8.3%), and showed no improvement or worsening in 9 (12.5%). Patient age and premorbid weakness were the only factors found to be significantly associated with outcome (p = 0.04 and 0.012, respectively).
These results strongly support immediate surgical decompression combined with appropriately tailored antibiotic therapy for the treatment of symptomatic SEA presenting with focal neurological deficit. The nonsuperiority discovered in other patient subsets may be due to allocation biases between surgically treated and nonsurgically treated cohorts. The present data demonstrate the accuracy of peripheral blood culture for the prediction of causative organisms and confirm patient age as a predictor of outcomes.
A systematic review
Venkatesh S. Madhugiri, Sudheer Ambekar, V. R. Roopesh Kumar, Gopalakrishnan M. Sasidharan and Anil Nanda
Spinal aneurysms (SAs) are rare lesions. The clinicoradiological features and the exact degree of their association with comorbid conditions such as arteriovenous malformations (AVMs) and coarctation of the aorta have not been definitively described. The ideal management paradigm has not been established. The authors reviewed literature to determine the clinical patterns of presentation, management, and outcome of spinal aneurysms.
A systematic review of literature was performed using 23 separate strings. A total of 10,190 papers were screened to identify 87 papers that met the inclusion criteria. A total of 123 SAs could be included for analysis.
The mean age of patients at presentation was 38 years; 10% of patients were aged less than 10 years and nearly 50% were greater than 38 years. Spinal aneurysms can be divided into 2 groups: those associated with AVMs (SA-AVMs, or Type 1 SAs) and those with isolated aneurysms (iSAs, or Type 2 SAs). Patients with Type 2 SAs were older and more likely to present with bleeding than those with Type 1 SAs. The acute syndromes can be divided into 3 groups of patients: those with spinal syndrome, those with cranial/craniospinal syndrome, and those with nonspecific presentation. Overall, 32.6% presented with angiography-negative cranial subarachnoid hemorrhage (SAH). Presentation with evidence of cord dysfunction (myelopathy/weakness/sensory loss/bladder involvement) correlated with poor outcome, as did presentation with hemorrhage and association with other comorbid conditions. Surgery and endovascular therapy both led to comparable rates of complete aneurysm obliteration for Type 2 SAs, whereas for the AVM-associated Type 1 SAs, surgery led to better rates of lesion obliteration. The authors propose a classification scheme for spinal aneurysms based on whether the lesion is solitary or is associated with a coexistent spinal AVM; this would also imply that the ideal therapy for the aneurysm would differ based on this association.
The clinical and radiological patterns that influence outcome are distinct for Type 1 and Type 2 SAs. The ideal treatment for Type 1 SAs appears to be excision, whereas surgery and endovascular therapy were equally effective for Type 2 SAs.
Imad Saeed Khan, Ashish Sonig, Jai Deep Thakur, Papireddy Bollam and Anil Nanda
Transforaminal lumbar interbody fusion (TLIF) has been increasingly used to treat degenerative spine disease, including that in patients in whom earlier decompressive procedures have failed. Reexploration in these cases is always challenging and is thought to pose a higher risk of complications. To the best of the authors' knowledge, there are no current studies specifically analyzing the effects of previous lumbar decompressive surgeries on the complication rates of open TLIF.
The authors performed a retrospective study of surgeries performed by a single surgeon. A total of 187 consecutive patients, in whom the senior author (A.N.) had performed open TLIF between January 2007 and January 2011, met the inclusion criteria. The patients were divided into two groups (primary and revision TLIF) for the comparison of perioperative complications.
Overall, the average age of the patients was 49.7 years (range 18–80 years). Of the 187 patients, 73 patients had no history of lumbar surgery and 114 were undergoing revision surgery. Fifty-four patients (28.9%) had a documented complication intraoperatively or postoperatively. There was no difference in the rate on perioperative complications between the two groups (overall, medical, wound related, inadvertent dural tears [DTs], or neural injury). Patients who had undergone more than one previous lumbar surgery were, however, more likely to have suffered from DTs (p = 0.054) and neural injuries (p = 0.007) compared with the rest.
In the hands of an experienced surgeon, revision open TLIF does not necessarily increase the risk of perioperative complications compared with primary TLIF. Two or more previous lumbar decompressive procedures, however, increase the risk of inadvertent DTs and neural injury.
Alexander R. Vaccaro
Ali Nourbakhsh, Shashikant Patil, Prasad Vannemreddy, Alan Ogden, Debi Mukherjee and Anil Nanda
Anterior screw fixation of the Type II odontoid fracture stabilizes the odontoid without restricting the motion of the cervical spine. The metal screw may limit bone remodeling because of stress shielding (if not placed properly) and limit imaging of the fracture. The use of bioabsorbable screws can overcome such shortcomings of the metal screws. The purpose of this study was to compare the strength of a 5-mm bioabsorbable screw with single 4-mm metal and double 3.5-mm lag screw fixation for Type II fractures of the odontoid process.
Three different modalities of anterior screw fixation were used in 19 C-2 vertebrae. These fixation methods consisted of a single 5-mm cannulated bioabsorbable lag screw (Group A), a single 4-mm cannulated titanium lag screw (Group B), and two 3.5-mm cannulated titanium lag screws (Group C). Anteroposterior (AP) stiffness and rotational stiffness were evaluated in all constructs.
There was no statistical difference among the ages of the cadavers in each group (p = 0.52). The AP bending stiffness in Groups A, B, and C was 117 ± 86, 66 ± 43, and 305 ± 130 Nm/mm, respectively. The AP bending stiffness in Group C was significantly higher than that in Groups A and B (p = 0.01 and p = 0.001, respectively). The difference in AP bending stiffness values of bioabsorbable and 4-mm metal screws was not statistically significant (p = 0.23). The rotational stiffness of the double 3.5-mm metal screws was significantly greater than that of the 5-mm bioabsorbable and the 4-mm titanium screws.
Double screw fixation with 3.5-mm screws provides the stiffest construct in Type II odontoid fractures. Bioabsorbable lag screws (5 mm) have the same AP bending and rotational stiffness as the single titanium lag screw (4 mm) in odontoid fractures.