Tag: preoperative planning

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Surgical treatment of meningiomas located in the rolandic area

J Neurosurg 133:107–118, 2020

Surgical treatment of convexity meningiomas is usually considered a low-risk procedure. Nevertheless, the risk of postoperative motor deficits is higher (7.1%–24.7% of all cases) for lesions located in the rolandic region, especially when an arachnoidal cleavage plane with the motor pathway is not identifiable. The authors analyzed the possible role of navigated transcranial magnetic stimulation (nTMS) for planning resection of rolandic meningiomas and predicting the presence or lack of an intraoperative arachnoidal cleavage plane as well as the postoperative motor outcome.

METHODS Clinical data were retrospectively collected from surgical cases involving patients affected by convexity, parasagittal, or falx meningiomas involving the rolandic region, who received preoperative nTMS mapping of the motor cortex (M1) and nTMS-based diffusion tensor imaging (DTI) fiber tracking of the corticospinal tract before surgery at 2 different neurosurgical centers. Surgeons’ self-reported evaluation of the impact of nTMS-based mapping on surgical strategy was analyzed. Moreover, the nTMS mapping accuracy was evaluated in comparison with intraoperative neurophysiological mapping (IONM). Lastly, we assessed the role of nTMS as well as other pre- and intraoperative parameters for predicting the patients’ motor outcome and the presence or absence of an intraoperative arachnoidal cleavage plane.

RESULTS Forty-seven patients were included in this study. The nTMS-based planning was considered useful in 89.3% of cases, and a change of the surgical strategy was observed in 42.5% of cases. The agreement of nTMS-based planning and IONM-based strategy in 35 patients was 94.2%. A new permanent motor deficit occurred in 8.5% of cases (4 of 47). A higher resting motor threshold (RMT) and the lack of an intraoperative arachnoidal cleavage plane were the only independent predictors of a poor motor outcome (p = 0.04 and p = 0.02, respectively). Moreover, a higher RMT and perilesional edema also predicted the lack of an arachnoidal cleavage plane (p = 0.01 and p = 0.03, respectively). Preoperative motor status, T2 cleft sign, contrast-enhancement pattern, and tumor volume had no predictive value.

CONCLUSIONS nTMS-based motor mapping is a useful tool for presurgical assessment of rolandic meningiomas, especially when a clear cleavage plane with M1 is not present. Moreover, the RMT can indicate the presence or absence of an intraoperative cleavage plane and predict the motor outcome, thereby helping to identify high-risk patients before surgery.

 

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The value of sitting radiographs: analysis of spine flexibility and its utility in preoperative planning for adult spinal deformity surgery

J Neurosurg Spine 29:414–421, 2018

Preoperative planning of thoracolumbar deformity (TLD) surgery has been shown to improve radiographic and clinical outcomes. One of the confounders in attaining optimal postoperative alignment is the reciprocal hyperkyphosis of unfused thoracic segments. Traditional planning utilizes standing radiographs, but the value of sitting radiographs to predict thoracic flexibility has not been investigated. Authors of the present study propose that alignment changes from a sitting to a standing position will predict changes in unfused thoracic segments after TLD correction.

METHODS Patients with degenerative spine pathology underwent preoperative sitting and standing full-spine stereotactic radiography. A subset of TLD patients who had undergone corrections with minimum T10-pelvis fusions was analyzed in terms of pre- to postoperative alignment. Radiographic parameters were analyzed, including the T1 pelvic angle (TPA), T1–L1 pelvic angle (TLPA), lumbar pelvic angle (LPA), pelvic tilt (PT), mismatch between pelvic incidence and lumbar lordosis (PI-LL mismatch), and T2–12 kyphosis (TK). Thoracic compensation was calculated as the expected TK minus actual TK (i.e., [2/3 × PI] – actual TK). Statistical analysis consisted of paired and unpaired t-tests and linear regression analysis.

RESULTS The authors retrospectively identified 137 patients with full-body standing and sitting radiographs. The mean age of the patients was 60.9 years old, 60.0% were female, and the mean BMI was 27.8 kg/m2. The patients demonstrated significantly different radiographic alignments in baseline spinopelvic and global parameters from the preoperative sitting versus the standing positions: LL (-34.20° vs -47.87°, p < 0.001), PT (28.31° vs 17.50°, p < 0.001), TPA (27.85° vs 16.89°, p < 0.001), TLPA (10.63° vs 5.17°, p < 0.001), and LPA (15.86° vs 9.67°, p < 0.001). Twenty patients (65.0% female) with a mean age of 65.3 years and mean BMI of 30.2 kg/m2 had TLD and underwent surgical correction (pre- to postoperative standing change in TPA: 33.90° to 24.50°, p = 0.001). Preoperative sitting radiographs demonstrated significant differences in alignment compared to postoperative standing radiographs: larger TPA (39.10° vs 24.50°, p < 0.001), PT (35.40° vs 28.10°, p < 0.001), LL (-11.20° vs -44.80°, p < 0.001), LPA (22.80° vs 14.20°, p < 0.001), and unfused Cobb (T2 to upper instrumented vertebra [UIV] Cobb angle: 19.95° vs 27.50°, p = 0.039). Also in the TLD group, mean thoracic compensation was 6.75°. In the linear regression analysis, the change from sitting to standing predicted pre- to postoperative changes for TK and the unfused thoracic component of TPA (5° change in preoperative sitting to preoperative standing corresponded to a pre- to postoperative change in standing TK of 6.35° and in standing TPA of 7.23°, R2 = 0.30 and 0.38, respectively).

CONCLUSIONS Sitting radiographs were useful in demonstrating spine flexibility. Among the TLD surgery group, relaxation of the unfused thoracic spine in the sitting position predicted the postoperative increase in kyphosis of the unfused thoracic segments. Sitting radiographs are a useful tool to anticipate reciprocal changes in thoracic alignment that diminish global corrections.

 

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Preoperative full-length standing radiographs and revision rates in lumbar degenerative scoliosis

J Neurosurg Spine 28:581–585, 2018

Full-length (36-inch) standing spine radiographs are commonly used by spine surgeons to evaluate patients with lumbar degenerative scoliosis (LDS). Despite this practice, the impact of these images on preoperative decision making and the rate of revision surgery has not been analyzed. The purpose of this study is to determine if preoperative full-length standing spine radiographs improve surgical decision making by decreasing the rate of revision surgery in patients with LDS.

METHODS From the Health Care Service Corporation administrative claims database, the authors identified patients 50–80 years of age with LDS who had undergone surgery including posterior lumbar decompression and fusion over 2–6 levels and with at least 5 years of continuous coverage after the index surgery. Patients were stratified into the following groups, according to the preoperative imaging studies performed within 6 months before their index surgery: lumbar spine MRI studies only, lumbar spine MRI studies and standard lumbar spine radiographs, CT myelograms, and full-length standing spine radiographs. Survival analysis was performed with the occurrence of a revision within 5 years of the index surgery as the outcome of interest.

RESULTS A total of 411 patients were included in the study after applying the inclusion and exclusion criteria. Revision surgery within 5 years after the index procedure was most frequent in the patients with preoperative MRI only (41.8%), followed by the patients with a CT myelogram (30.4%) and those with MRI and standard radiographs (24.8%). The lowest revision rate was seen among those with long-cassette standing radiographs (11.1%). Patients whose preoperative evaluation included full-length standing radiographs (OR 0.353, p = 0.034) and MRI studies plus radiographs (OR 0.650, p = 0.022) were less likely to require revision surgery at 5 years after the index procedure.

CONCLUSIONS An assessment of standing alignment using full-length (36-inch) standing radiographs may be beneficial in reducing the risk of revision surgery in patients with lumbar scoliosis. This observation was not limited to patients with large curves or substantial deformity.

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Preoperative planning of hemangioblastoma using 3D imaging

 

J Neurosurg 127:139–147, 2017

Successful resection of hemangioblastoma depends on preoperative assessment of the precise locations of feeding arteries and draining veins. Simultaneous 3D visualization of feeding arteries, draining veins, and surrounding structures is needed.

The present study evaluated the usefulness of high-resolution 3D multifusion medical imaging (hr-3DMMI) for preoperative planning of hemangioblastoma. The hr-3DMMI combined MRI, MR angiography, thin-slice CT, and 3D rotated angiography. Surface rendering was mainly used for the creation of hr-3DMMI using multiple thresholds to create 3D models, and processing took approximately 3–5 hours. This hr-3DMMI technique was used in 5 patients for preoperative planning and the imaging findings were compared with the operative findings. Hr-3DMMI could simulate the whole 3D tumor as a unique sphere and show the precise penetration points of both feeding arteries and draining veins with the same spatial relationships as the original tumor.

All feeding arteries and draining veins were found intraoperatively at the same position as estimated preoperatively, and were occluded as planned preoperatively. This hr-3DMMI technique could demonstrate the precise locations of feeding arteries and draining veins preoperatively and estimate the appropriate route for resection of the tumor. Hr-3DMMI is expected to be a very useful support tool for surgery of hemangioblastoma.

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