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Ricardo B. V. Fontes and Vincent C. Traynelis

Object

Minimally invasive lateral transpsoas interbody fusion (LTIF) has emerged as a popular surgical technique in a remarkably short period of time. The authors' experience with this procedure and anecdotal evidence in the literature suggest that the iliac crest may occasionally prevent access to the L4–5 interspace during minimally invasive LTIF. The authors propose that removal of a minimal amount of ilium would allow for successful exposure of the L4–5 interspace in those cases with a “high-riding” iliac crest. Therefore, the objective of this study was to evaluate the feasibility of iliac osteotomy to enhance exposure of the L4–5 interspace for minimally invasive LTIF.

Methods

Twenty L4–5 minimally invasive LTIF procedures were performed on 10 cadavers. The L4–5 minimally invasive LTIFs were successfully completed in 13 of 20 attempts. In the remaining 7 cases, the iliac crest prevented perfect orthogonal access to the L4–5 interspace. An iliac osteotomy was performed until the tubular retractors could be perfectly aligned with the L4–5 interspace and minimally invasive LTIF accomplished. Anteroposterior fluoroscopic images were obtained before and after the osteotomies. The angle between the working instrument and the superior L-5 endplate was measured, as were craniocaudal displacement and the resected iliac area.

Results

Iliac osteotomy enabled completion of L4–5 minimally invasive LTIF in the 7 remaining cases. Iliac resection was minimal; an average of 4.92 cm2 of iliac surface was resected (range 2.08–8.27 cm2) to enable L4–5 access. Adequate working angles were maintained (average 3.3° change after resection) while significant caudal displacement of the tubular system was achieved (average 15.7 mm, range 5.2–27.6 mm).

Conclusions

A significant portion of patients may have a high-riding iliac crest and that may have had an impact on minimally invasive LTIF in this series; L4–5 cases are rare in relation to midlumbar spine cases in most minimally invasive LTIF patient series. Significant caudal displacement of the tubular system was achieved with minimal iliac osteotomy, ensuring access to the L4–5 interspace in all specimens while maintaining the minimally invasive philosophy behind minimally invasive LTIF.

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Robert G. Kellogg, Ricardo B. V. Fontes, and Demetrius K. Lopes

Fat embolism syndrome (FES) is a common clinical entity that can occasionally have significant neurological sequelae. The authors report a case of cerebral fat embolism and FES that required surgical management of intracranial pressure (ICP). They also discuss the literature as well as the potential need for neurosurgical management of this disease entity in select patients. A 58-year-old woman presented with a seizure episode and altered mental status after suffering a right femur fracture. Head CT studies demonstrated hypointense areas consistent with fat globules at the gray-white matter junction predominantly in the right hemisphere. This CT finding is unique in the literature, as other reports have not included imaging performed early enough to capture this finding. Brain MR images obtained 3 days later revealed T2-hyperintense areas with restricted diffusion within the same hemisphere, along with midline shift and subfalcine herniation. These findings steered the patient to the operating room for decompressive hemicraniectomy. A review of the literature from 1980 to 2012 disclosed 54 cases in 38 reports concerning cerebral fat embolism and FES. Analysis of all the cases revealed that 98% of the patients presented with mental status changes, whereas only 22% had focal signs and/or seizures. A good outcome was seen in 57.6% of patients with coma and/or abnormal posturing on presentation and in 90.5% of patients presenting with mild mental status changes, focal deficits, or seizure. In the majority of cases ICP was managed conservatively with no surgical intervention. One case featured the use of an ICP monitor, while none featured the use of hemicraniectomy.

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Ziev B. Moses, Seok Yoon Oh, Ricardo B. V. Fontes, Harel Deutsch, John E. O’Toole, and Richard G. Fessler

OBJECTIVE

The modified frailty index (mFI) is a simple tool that measures physiological reserve based on a thorough history and physical examination. Its use has been validated in several surgical specialties, including spinal deformity surgery. Prior research has suggested no significant differences in clinical outcomes between elderly and nonelderly patients undergoing posterior lumbar interbody fusion. The authors sought to investigate the use of the mFI in patients undergoing transforaminal lumbar interbody fusion (TLIF) and the relationship between frailty scores and clinical outcomes.

METHODS

A retrospective chart review was conducted on 198 patients who underwent a single-level TLIF over a 60-month period at a single institution. For all patients, an mFI score was computed incorporating a set of 11 clinical factors to assess preexisting comorbidities and functional status. Clinical follow-up and health-related quality-of-life (HRQOL) scores were obtained at baseline and regular intervals of 6 weeks, 6 months, and 1 year following surgery.

RESULTS

Patients were grouped according to their level of frailty: no frailty (mFI = 0), mild frailty (mFI = 0.09), moderate frailty (mFI = 0.18), and severe frailty (mFI ≥ 0.27). One-way ANOVA revealed increasing levels of frailty to be associated with an increased rate of complications, from 10.3% to 63.6%. In addition, increasing levels of frailty were associated with longer hospital length of stay (LOS), from 3.1 days to 6.5 days, and lower rates of disposition to home. At the 1-year follow-up, increased levels of frailty were associated with worse HRQOL measures.

CONCLUSIONS

Increasing mFI score was associated with higher morbidity, longer inpatient LOS, and a lower probability of discharge to home in patients undergoing single-level TLIF. Consideration of the mFI may help surgeons improve decision-making across the spectrum of patients who are at risk from frailty.

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Ricardo B. V. Fontes, Adam P. Smith, Lorenzo F. Muñoz, Richard W. Byrne, and Vincent C. Traynelis

Object

Early postoperative head CT scanning is routinely performed following intracranial procedures for detection of complications, but its real value remains uncertain: so-called abnormal results are frequently found, but active, emergency intervention based on these findings may be rare. The authors' objective was to analyze whether early postoperative CT scans led to emergency surgical interventions and if the results of neurological examination predicted this occurrence.

Methods

The authors retrospectively analyzed 892 intracranial procedures followed by an early postoperative CT scan performed over a 1-year period at Rush University Medical Center and classified these cases according to postoperative neurological status: baseline, predicted neurological change, unexpected neurological change, and sedated or comatose. The interpretation of CT results was reviewed and unexpected CT findings were classified based on immediate action taken: Type I, additional observation and CT; Type II, active nonsurgical intervention; and Type III, surgical intervention. Results were compared between neurological examination groups with the Fisher exact test.

Results

Patients with unexpected neurological changes or in the sedated or comatose group had significantly more unexpected findings on the postoperative CT (p < 0.001; OR 19.2 and 2.3, respectively) and Type II/III interventions (p < 0.001) than patients at baseline. Patients at baseline or with expected neurological changes still had a rate of Type II/III changes in the 2.2%–2.4% range; however, no patient required an immediate return to the operating room.

Conclusions

Over a 1-year period in an academic neurosurgery service, no patient who was neurologically intact or who had a predicted neurological change required an immediate return to the operating room based on early postoperative CT findings. Obtaining early CT scans should not be a priority in these patients and may even be cancelled in favor of MRI studies, if the latter have already been planned and can be performed safely and in a timely manner. Early postoperative CT scanning does not assure an uneventful course, nor should it replace accurate and frequent neurological checks, because operative interventions were always decided in conjunction with the neurological examination.

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Lee A. Tan, Manish K. Kasliwal, Nakhle Mhanna, Ricardo B. V. Fontes, and Vincent C. Traynelis

Subependymomas can rarely occur in the spinal cord, and account for about 2% of symptomatic spinal cord tumors. It most often occurs in the cervical spinal cord, followed by cervicothoracic junction, thoracic cord and conus medullaris. It often has an eccentric location in the spinal cord and lacks gadolinium enhancement on magnetic resonance imaging. We present a rare case of symptomatic subependymoma of the cervical spinal cord, which underwent successful gross total resection. Surgical pearls and nuances are discussed to help surgeons to avoid potential complications.

The video can be found here: http://youtu.be/Rsm9KxZX7Yo.

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Lee A. Tan, Manish K. Kasliwal, Joshua Wewel, Ricardo B. V. Fontes, and John E. O'Toole

Schwannomas are the most common intradural-extramedullary spinal tumors, with an estimated incidence of 3 to 10 cases per 100,000 people. With continued advances in minimally invasive surgery (MIS) over recent years, MIS techniques have been utilized by spine surgeons in the resection of intradural spinal neoplasms with favorable surgical results and clinical outcomes. This video demonstrates a rare case of symptomatic, synchronous, same-level lumbar intradural-extramedullary neoplasm and acute disc herniation, both of which were successfully treated using a single MIS approach. Surgical pearls and nuances are discussed to better delineate technique and minimize potential complications.

The video can be found here: http://youtu.be/78ibbicBRUk.

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Ricardo B. V. Fontes and Vincent C. Traynelis

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Lee A. Tan, Manish K. Kasliwal, Ricardo B. V. Fontes, and Richard G. Fessler