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Junseok Bae, Alexander A. Theologis, Russell Strom, Bobby Tay, Shane Burch, Sigurd Berven, Praveen V. Mummaneni, Dean Chou, Christopher P. Ames and Vedat Deviren

OBJECTIVE

Surgical treatment of adult spinal deformity (ASD) is an effective endeavor that can be accomplished using a variety of surgical strategies. Here, the authors assess and compare radiographic data, complications, and health-related quality-of-life (HRQoL) outcome scores among patients with ASD who underwent a posterior spinal fixation (PSF)–only approach, a posterior approach combined with lateral lumbar interbody fusion (LLIF+PSF), or a posterior approach combined with anterior lumbar interbody fusion (ALIF+PSF).

METHODS

The medical records of consecutive adults who underwent thoracolumbar fusion for ASD between 2003 and 2013 at a single institution were reviewed. Included were patients who underwent instrumentation from the pelvis to L-1 or above, had a sagittal vertical axis (SVA) of < 10 cm, and underwent a minimum of 2 years’ follow-up. Those who underwent a 3-column osteotomy were excluded. Three groups of patients were compared on the basis of the procedure performed, LLIF+PSF, ALIF+PSF, and PSF only. Perioperative spinal deformity parameters, complications, and HRQoL outcome scores (Oswestry Disability Index [ODI], Scoliosis Research Society 22-question Questionnaire [SRS-22], 36-Item Short Form Health Survey [SF-36], visual analog scale [VAS] for back/leg pain) from each group were assessed and compared with each other using ANOVA. The minimal clinically important differences used were −1.2 (VAS back pain), −1.6 (VAS leg pain), −15 (ODI), 0.587/0.375/0.8/0.42 (SRS-22 pain/function/self-image/mental health), and 5.2 (SF-36, physical component summary).

RESULTS

A total of 221 patients (58 LLIF, 91 ALIF, 72 PSF only) met the inclusion criteria. Average deformities consisted of a SVA of < 10 cm, a pelvic incidence–lumbar lordosis (LL) mismatch of > 10°, a pelvic tilt of > 20°, a lumbar Cobb angle of > 20°, and a thoracic Cobb angle of > 15°. Preoperative SVA, LL, pelvic incidence–LL mismatch, and lumbar and thoracic Cobb angles were similar among the groups. Patients in the PSF-only group had more comorbidities, those in the ALIF+PSF group were, on average, younger and had a lower body mass index than those in the LLIF+PSF group, and patients in the LLIF+PSF group had a significantly higher mean number of interbody fusion levels than those in the ALIF+PSF and PSF-only groups. At final follow-up, all radiographic parameters and the mean numbers of complications were similar among the groups. Patients in the LLIF+PSF group had proximal junctional kyphosis that required revision surgery significantly less often and fewer proximal junctional fractures and vertebral slips. All preoperative HRQoL scores were similar among the groups. After surgery, the LLIF+PSF group had a significantly lower ODI score, higher SRS-22 self-image/total scores, and greater achievement of the minimal clinically important difference for the SRS-22 pain score.

CONCLUSIONS

Satisfactory radiographic outcomes can be achieved similarly and adequately with these 3 surgical approaches for patients with ASD with mild to moderate sagittal deformity. Compared with patients treated with an ALIF+PSF or PSF-only surgical strategy, patients who underwent LLIF+PSF had lower rates of proximal junctional kyphosis and mechanical failure at the upper instrumented vertebra and less back pain, less disability, and better SRS-22 scores.

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Michael M. Safaee, Russ Lyon, Nicholas M. Barbaro, Dean Chou, Praveen V. Mummaneni, Philip R. Weinstein, Cynthia T. Chin, Tarik Tihan and Christopher P. Ames

OBJECTIVE

Among all primary spinal neoplasms, approximately two-thirds are intradural extramedullary lesions; nerve sheath tumors, mainly neurofibromas and schwannomas, comprise approximately half of them. Given the rarity of these lesions, reports of surgical complications are limited. The aim of this study was to identify the rates of new or worsening neurological deficits and surgical complications associated with the resection of spinal nerve sheath tumors and the potential factors related to these outcomes.

METHODS

Patients were identified through a search of an institutional neuropathology database and a separate review of current procedural terminology (CPT) codes. Age, sex, clinical presentation, presence of neurofibromatosis (NF), tumor type, tumor location, extent of resection characterized as gross total or subtotal, use of intraoperative neuromonitoring, surgical complications, presence of neurological deficit, and clinical follow-up were recorded.

RESULTS

Two hundred twenty-one tumors in 199 patients with a mean age of 45 years were identified. Fifty-three tumors were neurofibromas; 163, schwannomas; and 5, malignant peripheral nerve sheath tumors (MPNSTs). There were 70 complications in 221 cases, a rate of 32%, which included 34 new or worsening sensory symptoms (15%), 12 new or worsening motor deficits (5%), 10 CSF leaks or pseudomeningoceles (4%), 11 wound infections (5%), 5 cases of spinal deformity (2%), and 6 others (2 spinal epidural hematomas, 1 nonoperative cranial subdural hematoma, 1 deep venous thrombosis, 1 case of urinary retention, and 1 recurrent laryngeal nerve injury). Complications were more common in cervical (36%) and lumbosacral (38%) tumors than in thoracic (18%) lesions (p = 0.021). Intradural and dumbbell lesions were associated with higher rates of CSF leakage, pseudomeningocele, and wound infection. Complications were present in 18 neurofibromas (34%), 50 schwannomas (31%), and 2 MPNSTs (40%); the differences in frequency were not significant (p = 0.834). Higher complication rates were observed in patients with NF than in patients without (38% vs 30%, p = 0.189), although rates were higher in NF Type 2 than in Type 1 (64% vs 31%). There was no difference in the use of intraoperative neuromonitoring when comparing cases with surgical complications and those without (67% vs 69%, p = 0.797). However, the use of neuromonitoring was associated with a significantly higher rate of gross-total resection (79% vs 66%, p = 0.022).

CONCLUSIONS

Resection is a safe and effective treatment for spinal nerve sheath tumors. Approximately 30% of patients developed a postoperative complication, most commonly new or worsening sensory deficits. This rate probably represents an inevitable complication of nerve sheath tumor surgery given the intimacy of these lesions with functional neural elements.

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Michael Safaee, Andrew T. Parsa, Nicholas M. Barbaro, Dean Chou, Praveen V. Mummaneni, Philip R. Weinstein, Tarik Tihan and Christopher P. Ames

OBJECT

Intradural extramedullary spine tumors represent two-thirds of all primary spine neoplasms. Approximately half of these are peripheral nerve sheath tumors, mainly neurofibromas and schwannomas. Given the rarity of this disease and, thus, the limited analyses of clinical outcomes, the authors examined the association of tumor location, extent of resection, and neurofibromatosis (NF) status with clinical outcomes.

METHODS

Patients were identified through a search of the University of California, San Francisco, neuropathology database and a separate review of current procedural terminology codes. Data recorded included patient age, patient sex, clinical presentation, presence of NF, tumor type, tumor location, extent of resection (gross-total resection [GTR] or subtotal resection [STR]), and clinical follow-up.

RESULTS

Of 221 tumors in 199 patients (mean age 45 years), 53 were neurofibromas, 163 were schwannomas, and 5 were malignant peripheral nerve sheath tumors. The most common presenting symptom was spinal pain (76%), followed by weakness (36%) and sensory abnormalities (34%). Mean symptom duration was 16 months. In terms of spinal location, neurofibromas were more common in the cervical spine (74% vs 27%, p < 0.001), and schwannomas were more common in the thoracic and lumbosacral spine (73% vs 26%, p < 0.001). Rates of GTR were lower for neurofibromas than schwannomas (51% vs 83%, p < 0.001), regardless of location. Rates of GTR were lower for cervical (54%) than thoracic (90%) and lumbosacral (86%) lesions (p < 0.001). NF was associated with lower rates of GTR among all tumors (43% vs 86%, p < 0.001). The mean follow-up time was 32 months. Recurrence/progression was more common for neurofibromas than schwannomas (17% vs 7%, p = 0.03), although the mean time to recurrence/progression did not differ according to tumor type (45 vs 53 months, p = 0.63). As expected, GTR was associated with lower recurrence rates (4% vs 22%, p < 0.001). According to multivariate analysis, cervical location (OR 0.239, 95% CI 0.110–0.520) and presence of NF (OR 0.166, 95% CI 0.054–0.507) were associated with lower rates of GTR. In a separate model, only GTR (OR 0.141, 95% CI 0.046–0.429) was associated with tumor recurrence.

CONCLUSIONS

Resection is an effective treatment for spinal nerve sheath tumors. Neurofibromas were found more commonly in the cervical spine than in other regions of the spine and were associated with higher rates of recurrence and lower rates of GTR than other tumor types, particularly in patients with NF Types 1 or 2. According to multivariate analysis, both cervical location and presence of NF were associated with lower rates of GTR. According to a second multivariate model, the only variable associated with tumor recurrence was extent of resection. Maximal safe resection remains ideal for these lesions; however, patients with cervical tumors or NF should be counseled about their increased risk for recurrence.

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Camilo A. Molina, Christopher P. Ames, Dean Chou, Laurence D. Rhines, Patrick C. Hsieh, Patricia L. Zadnik, Jean-Paul Wolinsky, Ziya L. Gokaslan and Daniel M. Sciubba

Object

Chordomas involving the mobile spine are ideally managed via en bloc resection with reconstruction to optimize local control and possibly offer cure. In the cervical spine, local anatomy poses unique challenges, limiting the feasibility of aggressive resection. The authors present a multi-institutional series of 16 cases of cervical chordomas removed en bloc. Particular attention was paid to clinical outcome, complications, and recurrence. In addition, outcomes were assessed according to position of tumor at the C1–2 level versus the subaxial (SA) spine (C3–7).

Methods

The authors reviewed cases involving patients who underwent en bloc resection of cervical chordoma at 4 large spine centers. Patients were included if the lesion epicenter involved the C-1 to C-7 vertebral bodies. Demographic data and details of surgery, follow-up course, exposure to adjuvant therapy, and complications were obtained. Outcome was correlated with presence of tumor in C1–2 versus subaxial spine via a Student t-test.

Results

Sixteen patients were identified (mean age at presentation 55 ± 14 years). Seven cases (44%) cases involved C1–2, and 16 involved the subaxial spine. Median survival did not differ significantly different between the C1–2 (72 months) and SA (60 months) groups (p = 0.65). A combined (staged anteroposterior) approach was used in 81% of the cases. Use of the combined approach was significantly more common in treatment of subaxial than C1–2 tumors (100% vs 57%, p = 0.04). En bloc resection was attempted via an anterior approach in 6% of cases (C1–2: 14.3%; SA: 0%; p = 0.17) and a posterior approach in 13% of cases (C1–2: 29%; SA: 0%; p = 0.09). The most commonly reported margin classification was marginal (56% of cases), followed by violated (25%) and wide (19%). En bloc excision of subaxial tumors was significantly more likely to result in marginal margins than excision of C1–2 tumors (C1–2: 29%; SA: 78%; p = 0.03). C1–2 tumors were associated with significantly higher rates of postoperative complications (C1–2: 71%; SA: 22%; p = 0.03). Both local and distant tumor recurrence was greatest for C1–2 tumors (local C1–2: 29%; local SA: 11%; distant C1–2: 14%; distant SA: 0%). Statistical analysis of tumor recurrence based on tumor location was not possible due to the small number of cases. There was no between-groups difference in exposure to postoperative adjuvant radiotherapy. There was no difference in median survival between groups receiving proton beam radiotherapy or intensity-modulated radiotherapy versus no radiation therapy (p = 0.8).

Conclusions

Compared with en bloc resection of chordomas involving the subaxial cervical spine, en bloc resection of chordomas involving the upper cervical spine (C1–2) is associated with poorer outcomes, such as less favorable margins, higher rates of complications, and increased tumor recurrence. Data from this cohort do not support a statistically significant difference in survival for patients with C1–2 versus subaxial disease, but larger studies are needed to further study survival differences.

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Michael Safaee, Michael C. Oh, Praveen V. Mummaneni, Philip R. Weinstein, Christopher P. Ames, Dean Chou, Mitchel S. Berger, Andrew T. Parsa and Nalin Gupta

Object

Ependymomas are a common type of CNS tumor in children, although only 13% originate from the spinal cord. Aside from location and extent of resection, the factors that affect outcome are not well understood.

Methods

The authors performed a search of an institutional neuropathology database to identify all patients with spinal cord ependymomas treated over the past 20 years. Data on patient age, sex, clinical presentation, symptom duration, tumor location, extent of resection, use of radiation therapy, surgical complications, presence of tumor recurrence, duration of follow-up, and residual symptoms were collected. Pediatric patients were defined as those 21 years of age or younger at diagnosis. The extent of resection was defined by the findings of the postoperative MR images.

Results

A total of 24 pediatric patients with spinal cord ependymomas were identified with the following pathological subtypes: 14 classic (Grade II), 8 myxopapillary (Grade I), and 2 anaplastic (Grade III) ependymomas. Both anaplastic ependymomas originated in the intracranial compartment and spread to the spinal cord at recurrence. The mean follow-up duration for patients with classic and myxopapillary ependymomas was 63 and 45 months, respectively. Seven patients with classic ependymomas underwent gross-total resection (GTR), while 4 received subtotal resection (STR), 2 received STR as well as radiation therapy, and 1 received radiation therapy alone. All but 1 patient with myxopapillary ependymomas underwent GTR. Three recurrences were identified in the Grade II group at 45, 48, and 228 months. A single recurrence was identified in the Grade I group at 71 months. The mean progression-free survival (PFS) was 58 months in the Grade II group and 45 months in the Grade I group.

Conclusions

Extent of resection is an important prognostic factor in all pediatric spinal cord ependymomas, particularly Grade II ependymomas. These data suggest that achieving GTR is more difficult in the upper spinal cord, making tumor location another important factor. Although classified as Grade I lesions, myxopapillary ependymomas had similar outcomes when compared with classic (Grade II) ependymomas, particularly with respect to PFS. Long-term complications or new neurological deficits were rare. Among patients with long-term follow-up, those who underwent GTR had a recurrence rate of 20% compared with 40% among those with STR or biopsy only, suggesting that extent of resection is perhaps a more important prognostic factor than histological grade in predicting PFS, which has been suggested by other data in the literature. Given the relative paucity of these lesions, collaborative multiinstitutional studies are needed, and such efforts should also focus on molecular and genetic analysis to refine the current classification system.

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Aaron J. Clark, John E. Ziewacz, Michael Safaee, Darryl Lau, Russ Lyon, Dean Chou, Philip R. Weinstein, Christopher P. Ames, John P. Clark III and Praveen V. Mummaneni

Object

The use of intraoperative neurophysiological monitoring (IONM) in surgical decompression surgery for myelopathy may assist the surgeon in taking corrective measures to reduce or prevent permanent neurological deficits. We evaluated the efficacy of IONM in cervical and cervicothoracic spondylotic myelopathy (CSM) cases.

Methods

The authors retrospectively reviewed 140 cases involving patients who underwent surgery for CSM utilizing IONM during 2011 at the University of California, San Francisco. Data on preoperative clinical variables, intraoperative changes in transcranial motor evoked potentials (MEPs), and postoperative new neurological deficits were collected. Associations between categorical variables were analyzed with the Fisher exact test.

Results

Of the 140 patients, 16 (11%) had significant intraoperative decreases in MEPs. In 8 of these cases, the MEP signal did not return to baseline values by the end of the operation. There were 8 (6%) postoperative deficits, of which 6 were C-5 palsies and 2 were paraparesis. Six of the patients with postoperative deficits had demonstrated persistent MEP signal change on IONM. There was a significant association between persistent MEP changes and postoperative deficits (p < 0.001). The sensitivity of intraoperative MEP monitoring was 75%, the specificity 98%, the positive predictive value 75%, and the negative predictive value 98%. Due to higher rates of false negatives, the sensitivity decreased to 60% in the subgroup of patients with vascular disease comorbidity. The sensitivity increased to 100% in elderly patients and in patients with preoperative motor deficits. The sensitivity and positive predictive value of deltoid and biceps MEP changes in predicting C-5 palsy were 67% and 67%, respectively.

Conclusions

The authors found a correlation between decreased intraoperative MEPs and postoperative new neurological deficits in patients with CSM. Sensitivity varies based on patient comorbidities, age, and preoperative neurological function. Monitoring of MEPs is a useful adjunct for CSM cases, and the authors have developed a checklist to standardize their responses to intraoperative MEP changes.