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Shane M. Burke, Mina G. Safain, James Kryzanski, and Ron I. Riesenburger

Lumbar nerve root anomalies are uncommon phenomena that must be recognized to avoid neural injury during surgery. The authors describe 2 cases of nerve root anomalies encountered during mini-open transforaminal lumbar interbody fusion (TLIF) surgery. One anomaly was a confluent variant not previously classified; the authors suggest that this variant be reflected in an amendment to the Neidre and Macnab classification system. They also propose strategies for identifying these anomalies and avoiding injury to anomalous nerve roots during TLIF surgery. Case 1 involved a 68-year-old woman with a 2-year history of neurogenic claudication. An MR image demonstrated L4–5 stenosis and spondylolisthesis and an L-4 nerve root that appeared unusually low in the neural foramen. During a mini-open TLIF procedure, a nerve root anomaly was seen. Six months after surgery this patient was free of neurogenic claudication. Case 2 involved a 60-year-old woman with a 1-year history of left L-4 radicular pain. Both MR and CT images demonstrated severe left L-4 foraminal stenosis and focal scoliosis. Before surgery, a nerve root anomaly was not detected, but during a unilateral mini-open TLIF procedure, a confluent nerve root was identified. Two years after surgery, this patient was free of radicular pain.

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Ron I. Riesenburger, G. Alexander Jones, Marie Roguski, and Ajit A. Krishnaney

Object

The goal of this study was to characterize the anatomy relevant to placement of crossing C-2 translaminar screws, including morphometric data, and to evaluate the risk of violating the vertebral artery (VA) during the screw placement. Placement of bilateral crossing C-2 translaminar screws has become an increasingly popular method for dorsal C-2 instrumentation as it is felt to avoid the known risk of VA injury associated with C1–2 transarticular screw fixation and C-1 lateral mass–C-2 pars screw fixation.

Methods

The source images from 50 CT angiograms of the neck obtained from October to November 2007 were studied. Digital imaging software was used to measure lamina thickness and maximum screw length, perform angulation of screw trajectories in the axial plane, and evaluate the potential for VA injury. In cases where the VA could be injured, the distance between the maximal screw length and artery was measured. Logistic regression was performed to evaluate lamina width, axial angle, and screw length for predicting the potential for VA injury.

Results

Mean lamina thickness, axial angle, and maximal screw length were determined for 100 laminae, and a potential for VA injury was noted in 55 laminae. The anatomically defined ideal screw length was longer in laminae with potential for VA injury than in laminae with no apparent risk (35.2 vs 33.6 mm, p = 0.0131). Only increasing optimal screw length was noted to be a statistically significant predictor of potential VA injury (p = 0.0159). The “buffer zone” (the distance between an optimally placed screw and the VA) was 5.6 ± 1.9 mm (mean ± SD, range 1.8–11.4 mm). A screw limited to 28 mm in length appeared to be safe in all laminae studied.

Conclusions

Crossing C-2 translaminar screws have been reported to be safe and effective. In addition to morphometric characteristics, the authors have found that screws placed in this trajectory could jeopardize the vertebral arteries in the foramen transversarium or the C1–2 interval. A C-2 translaminar screw limited to 28 mm in length appeared to be safe in all 100 screw trajectories studied in this series.

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Marie Roguski, Kyle Wu, Ron I. Riesenburger, and Julian K. Wu

Object

A primary goal in the treatment of patients with warfarin-associated subdural hematoma (SDH) is reversal of coagulopathy with fresh-frozen plasma. Achieving the traditional target international normalized ratio (INR) of 1.3 is often difficult and may expose patients to risks of volume overload and of thromboembolic complications. This retrospective study evaluates the risk of mild elevations of INR from 1.31 to 1.69 at 24 hours after admission in patients presenting with warfarin-associated SDH.

Methods

Sixty-nine patients with warfarin-associated SDH and 197 patients with non–warfarin-associated SDH treated at a single institution between January 2005 and January 2012 were retrospectively identified. Charts were reviewed for patient age, history of trauma, associated injuries, neurological status at presentation, size and chronicity of SDH, associated midline shift, INR at admission and at hospital Day 1 (HD1), concomitant aspirin or Plavix use, platelet count, and medical comorbidities. Patients were stratified according to use of warfarin and by INR at HD1 (INR 0.8–1.3, 1.31–1.69, 1.7–1.99, and ≥ 2). The groups were evaluated for differences the in rate of radiographic expansion of SDH and in the rate of clinically significant SDH expansion resulting in death, unplanned procedure, and/or readmission.

Results

There was no difference in the rate of radiographic versus clinically significant expansion of SDH between patients not on warfarin and those on warfarin (no warfarin: 22.3% vs 20.3%, p = 0.866; warfarin: 10.7% vs 11.6%, p = 0.825), but the rate of medical complications was significantly higher in the warfarin subgroup (13.3% for patients who did not receive warfarin vs 26.1% for those who did; p = 0.023). For warfarin-associated SDH, there was no difference in the rate of radiographic versus clinically significant expansion between patients reversed to HD1 INRs of 0.8–1.3 and 1.31–1.69 (HD1 INR 0.8–1.3: 22.5% vs 20%, p = 1; HD1 INR 1.31–1.69: 15% vs 10%, p = 0.71).

Conclusions

Mild INR elevations of 1.31–1.69 in warfarin-associated SDH are not associated with a markedly increased risk of radiographic or clinically significant expansion of SDH. Larger prospective studies are needed to determine if subtherapeutic INR elevations at HD1 are associated with smaller increases in risk of SDH expansion.

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Mina Safain, Matthew Shepard, Jason Rahal, James Kryzanski, Steven Hwang, Marie Roguski, and Ron I. Riesenburger

Treprostinil is a synthetic analog of prostacyclin, which is used for treatment of pulmonary arterial hypertension (PAH). Continuous subcutaneous administration of treprostinil has been proven in randomized controlled trials to improve quality of life, hemodynamics, and 5-year survival in patients with PAH. The efficacy of treprostinil has been attributed to its vasodilatory and antiplatelet effects. Unfortunately, the efficacy of treprostinil in the treatment of PAH is rapidly reversed upon cessation of the continuous infusion. Furthermore, cases of patients rapidly declining or succumbing to disease progression upon cessation of treprostinil have raised significant concern regarding discontinuation of this medication. To date, there are no reports of emergency craniotomies performed in the setting of continuous subcutaneous infusion of treprostinil. The authors report a case of a patient with PAH, treated with continuous administration of subcutaneous treprostinil as well as warfarin, who developed an acute subdural hematoma (SDH). Despite adequate INR (international normalized ratio) correction, the patient eventually underwent an emergency craniotomy for evacuation of the SDH while on continuous treprostinil administration. This case highlights the neurosurgical dilemma regarding the appropriate management of acute SDHs in patients receiving continuous treprostinil infusion.

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Clemens M. Schirmer, Steven W. Hwang, Ron I. Riesenburger, In Sup Choi, and Carlos A. David

Cobb syndrome represents the concurrent findings of a metameric spinal vascular malformation and a cutaneous vascular malformation within several dermatomes of each other. This rare entity engenders many difficult decisions with respect to appropriate therapeutic management. Historically, surgical excision carried a high morbidity, and conservative management without intervention was preferred. More recently, several cases of endovascular embolization have been reported with good success.

The authors describe the case of a 17-year-old boy who presented with a right gluteal angioma and was found to have a spinal arteriovenous malformation. Multiple embolizations failed to prevent neurological deterioration, and the patient eventually became wheelchair dependent. Surgical excision of the malformation led to partial recovery of neurological function, and at the latest follow-up, 52 months postoperatively, the patient was able to ambulate independently. This case demonstrates the successful treatment of a patient with Cobb syndrome with surgical excision after multiple refractory embolizations. A multidisciplinary approach, which balances the patient's current neurological function against the risks and potential gains from any interventional and surgical procedure, is recommended.

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Ron I. Riesenburger, Tejaswy Potluri, Nikhil Kulkarni, William Lavelle, Marie Roguski, Vijay K. Goel, and Edward C. Benzel

Object

Both ventral and dorsal operative approaches have been used to treat unilateral cervical facet injuries. The gold standard ventral approach is anterior cervical discectomy and fusion. There is, however, no clear gold standard dorsal operation. In this study, the authors tested the stability of multiple posterior constructs, including unilateral lateral mass fixation supplemented by an interspinous cable.

Methods

Six fresh human cervical spine specimens (C3–T1) were tested by applying pure moments to the C-3 vertebral body in increments of 0.5 Nm from 0 Nm to 2.0 Nm. Each specimen was tested in the following 8 conditions (in the order shown): 1) intact; 2) after destabilization via injury to the C5–6 facet; 3) with bilateral C5–6 lateral mass screws and rods; 4) after further destabilization by creating a right unilateral lateral mass fracture of C-5 (which rendered secure screw placement into the right C-5 lateral mass impossible); 5) with unilateral left C5–6 lateral mass screws and rod; 6) with unilateral C5–6 lateral mass screws and rod supplemented with an interspinous cable; 7) with a bilateral multilevel dorsal construct C4–6; and 8) after a C5–6 anterior cervical discectomy and fusion (ACDF) procedure with a polyetheretherketone graft and plate.

Results

The bilateral C5–6 lateral mass construct reduced the range of C5–6 motion to 33.6% of normal. The unilateral C5–6 lateral mass construct resulted in an increased range of motion to 110.1% of normal. The unilateral lateral mass construct supplemented by an interspinous cable reduced the C5–6 range of motion to 89.4% of normal. The bilateral C4–6 lateral mass construct reduced the C5–6 range of motion to 44.2% of normal. The C5–6 ACDF construct reduced the C5–6 range of motion to 62.6% of normal.

Conclusions

The unilateral lateral mass construct supplemented by an interspinous cable does reduce range of motion compared with an intact specimen, but is significantly inferior to a C4–6 bilateral lateral mass construct. When using a dorsal approach, the unilateral construct with a cable should only be considered in selected instances.

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Jeffrey M. Breton, Calvin G. Ludwig, Michael J. Yang, T. Jayde Nail, Ron I. Riesenburger, Penny Liu, and James T Kryzanski

OBJECTIVE

Spinal anesthesia (SA) is an alternative to general anesthesia (GA) for lumbar spine surgery, including complex instrumented fusion, although there are relatively few outcome data available. The authors discuss their experience using SA in a modern complex lumbar spine surgery practice to describe its utility and implementation.

METHODS

Data from patients receiving SA for lumbar spine surgery by one surgeon from March 2017 to December 2020 were collected via a retrospective chart review. Cases were divided into nonfusion and fusion procedure categories and analyzed for demographics and baseline medical status; pre-, intra-, and postoperative events; hospital course, including Acute Pain Service (APS) consults; and follow-up visit outcome data.

RESULTS

A total of 345 consecutive lumbar spine procedures were found, with 343 records complete for analysis, including 181 fusion and 162 nonfusion procedures and spinal levels from T11 through S1. The fusion group was significantly older (mean age 65.9 ± 12.4 vs 59.5 ± 15.4 years, p < 0.001) and had a significantly higher proportion of patients with American Society of Anesthesiologists (ASA) Physical Status Classification class III (p = 0.009) than the nonfusion group. There were no intraoperative conversions to GA, with infrequent need for a second dose of SA preoperatively (2.9%, 10/343) and rare preoperative conversion to GA (0.6%, 2/343) across fusion and nonfusion groups. Rates of complications during hospitalization were comparable to those seen in the literature. The APS was consulted for 2.9% (10/343) of procedures. An algorithm for the integration of SA into a lumbar spine surgery practice, from surgical and anesthetic perspectives, is also offered.

CONCLUSIONS

SA is a viable, safe, and effective option for lumbar spine surgery across a wide range of age and health statuses, particularly in older patients and those who want to avoid GA. The authors’ protocol, based in part on the largest set of data currently available describing complex instrumented fusion surgeries of the lumbar spine completed under SA, presents guidance and best practices to integrate SA into contemporary lumbar spine practices.

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Mark Henry, Katherine Scarlata, Ron I. Riesenburger, James Kryzanski, Leslie Rideout, Amer Samdani, Andrew Jea, and Steven W. Hwang

Object

Although MRI with short-term T1 inversion recovery (STIR) sequencing has been widely adopted in the clearance of cervical spine in adults who have sustained trauma, its applicability for cervical spine clearance in pediatric trauma patients remains unclear. The authors sought to review a Level 1 trauma center's experience using MRI for posttraumatic evaluation of the cervical spine in pediatric patients.

Methods

A pediatric trauma database was retrospectively queried for patients who received an injury warranting radiographic imaging of the cervical spine and had a STIR-MRI sequence of the cervical spine performed within 48 hours of injury between 2002 and 2011. Demographic, radiographic, and outcome data were retrospectively collected through medical records.

Results

Seventy-three cases were included in the analysis. The mean duration of follow-up was 10 months (range 4 days–7 years). The mean age of the patients at the time of trauma evaluation was 8.3 ± 5.8 years, and 65% were male. The majority of patients were involved in a motor vehicle accident. In 70 cases, the results of MRI studies were negative, and the patients were cleared prior to discharge with no clinical suggestion of instability on follow-up. In 3 cases, the MRI studies had abnormal findings; 2 of these 3 patients were cleared with dynamic radiographs during the same admission. Only 1 patient had an unstable injury and required surgical stabilization. The sensitivity of STIR MRI to detect cervical instability was 100% with a specificity of 97%. The positive predictive value was 33% and the negative predictive value was 100%.

Conclusions

Although interpretation of our results are diminished by limitations of the study, in our series, STIR MRI in routine screening for pediatric cervical trauma had a high sensitivity and slightly lower specificity, but may have utility in future practices and should be considered for implementation into protocols.

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Marie Roguski, Brent Morel, Megan Sweeney, Jordan Talan, Leslie Rideout, Ron I. Riesenburger, Neel Madan, and Steven Hwang

OBJECT

Traumatic head injury (THI) is a highly prevalent condition in the United States, and concern regarding excess radiation-related cancer mortality has placed focus on limiting the use of CT in the evaluation of pediatric patients with THI. Given the success of rapid-acquisition MRI in the evaluation of ventriculoperitoneal shunt malfunction in pediatric patient populations, this study sought to evaluate the sensitivity of MRI in the setting of acute THI.

METHODS

Medical records of 574 pediatric admissions for THI to a Level 1 trauma center over a 10-year period were retrospectively reviewed to identify patients who underwent both CT and MRI examinations of the head within a 5-day period. Thirty-five patients were found, and diagnostic images were available for 30 patients. De-identified images were reviewed by a neuroradiologist for presence of any injury, intracranial hemorrhage, diffuse axonal injury (DAI), and skull fracture. Radiology reports were used to calculate interrater reliability scores. Baseline demographics and concordance analysis was performed with Stata version 13.

RESULTS

The mean age of the 30-patient cohort was 8.5 ± 6.7 years, and 63.3% were male. The mean Injury Severity Score was 13.7 ± 9.2, and the mean Glasgow Coma Scale score was 9 ± 5.7. Radiology reports noted 150 abnormal findings. CT scanning missed findings in 12 patients; the missed findings included DAI (n = 5), subarachnoid hemorrhage (n = 6), small subdural hematomas (n = 6), cerebral contusions (n = 3), and an encephalocele. The CT scan was negative in 3 patients whose subsequent MRI revealed findings. MRI missed findings in 13 patients; missed findings included skull fracture (n = 5), small subdural hematomas (n = 4), cerebral contusions (n = 3), subarachnoid hemorrhage (n = 3), and DAI (n = 1). MRI was negative in 1 patient whose preceding CT scan was read as positive for injury. Although MRI more frequently reported intracranial findings than CT scanning, there was no statistically significant difference between CT and MRI in the detection of any intracranial injury (p = 0.63), DAI (p = 0.22), or intracranial hemorrhage (p = 0.25). CT scanning tended to more frequently identify skull fractures than MRI (p = 0.06).

CONCLUSIONS

MRI may be as sensitive as CT scanning in the detection of THI, DAI, and intracranial hemorrhage, but missed skull fractures in 5 of 13 patients. MRI may be a useful alternative to CT scanning in select stable patients with mild THI who warrant neuroimaging by clinical decision rules.

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Patrick J. Codd, Ron I. Riesenburger, Paul Klimo Jr., Jonathan R. Slotkin, and Edward R. Smith

✓ Aneurysmal bone cysts (ABCs) are benign, highly vascular osseous lesions characterized by cystic, blood-filled spaces surrounded by thin perimeters of expanded bone. Children and young adults are most often affected by spinal ABCs; more than 75% of patients are younger than 20 years old at presentation. Although ABCs have been documented in all areas of the axial and appendicular skeleton, ABCs of the spine present unique challenges due to the risk of vertebral destabilization, pathological fracture and vertebral body (VB) collapse, and neurological compromise. The authors describe the case of an 8-year-old child who presented with low-back pain and was subsequently found to have a lumbar ABC causing vertebra plana of the L-3 VB. They also review the literature on ABCs of the spine. This case highlights the importance of considering an ABC in the differential diagnosis when vertebra plana is seen in pediatric patients.