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Beejal Y. Amin, Tsung-Hsi Tu and Praveen V. Mummaneni

The potential advantages of a mini-open transforaminal interbody fusion (TLIF) operation are reduced blood loss, shorter length of stay, and less soft-tissue trauma compared to the standard open technique. Prior reports from our group and others have demonstrated successful outcomes using MIS techniques in lumbar fusion surgery.

In this 3D video, we demonstrate the key steps of the mini-open technique for a transforaminal lumbar interbody fusion using an expandable tubular retractor and contralateral percutaneous screw fixation for the treatment of a multiple recurrent disc herniation. The video demonstrates patient positioning, surgical opening with development of the Wiltse plane, placement of the tubular retractor, pedicle screw placement through both a percutaneous technique and a mini-open technique, decompression of the neural elements, graft insertion, and wound closure.

The video can be found here: http://youtu.be/LYRU9lbBdNg.

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Tsung-Hsi Tu, Jau-Ching Wu, Henrich Cheng and Praveen V. Mummaneni

For patients with multilevel cervical stenosis at nonadjacent segments, one of the traditional approaches has included a multilevel fusion of the abnormal segments as well as the intervening normal segment. In this video we demonstrate an alternative treatment plan with tailored use of a combination of anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) with an intervening skipped level.

The authors present the case of a 72-year-old woman with myeloradiculopathy and a large disc herniation with facet joint degeneration at C3–4 and bulging disc at C5–6. After nonoperative treatment failed, she underwent a single-level ACDF at C3–4 and single-level arthroplasty at C5–6, which successfully relieved her symptoms. No intervention was performed at the normal intervening C4–5 segment. By using ACDF combined with arthroplasty, the authors have avoided a 3-level fusion for this patient and maintained the range of motion of 2 disc levels.

The video can be found here: https://youtu.be/OrxcPUBvqLk.

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Jason S. Cheng, Cheerag Upadhyaya, Jau-Ching Wu, Tsung-Hsi Tu and Praveen V. Mummaneni

Minimally invasive surgical (MIS) approaches have gained popularity in many surgical fields. Potential advantages to a minimally invasive, spinal intradural approach include decreased operative blood loss, shorter hospitalization, and less post-operative pain. Potential disadvantages include longer operative times, decreased exposure, and difficulty closing the dura. Prior case series from our group and others have demonstrated successful tumor resections using MIS techniques without increased complications. In this 3D video, we demonstrate the key steps in our mini-open, transpinous approach for the resection of an intradural, extramedullary lumbar schwannoma. This operation is performed through a midline incision confined to one or two levels. The spinous process is removed. The paraspinal muscles are spread using a series of sequentially larger tubular dilators, and the first dilator is placed in the space previously occupied by the target level spinous process. The expandable tube retractor is then placed over the largest dilator and docked into place over the target laminae. The expandable tubular retractor is 6 centimeters in depth and 2.5 centimeters in width before expansion and is adjustable to 9 centimeters in depth and 4–5 centimeters in diameter which allows removal of intradural lesions confined to one or two spinal segments.

The video can be found here: http://youtu.be/l_C4VruKYng.

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Tsung-Hsi Tu, John E. Ziewacz and Praveen V. Mummaneni

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Tsung-Hsi Tu, John E. Ziewacz and Praveen V. Mummaneni

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Tsung-Hsi Tu, Chih-Chang Chang, Jau-Ching Wu, Li-Yu Fay, Wen-Cheng Huang and Henrich Cheng

The most commonly accepted indications for cervical disc arthroplasty (CDA) are 1- and 2-level cervical disc herniation or spondylosis causing radiculopathy or myelopathy that is refractory to medical management. Unlike anterior cervical discectomy and fusion (ACDF), which eliminates motion, CDA aims to restore the physiological range of motion of the indexed joint. Thus, the effect of indirect decompression gained by the insertion of a sufficiently large interbody graft and incorporation into arthrodesis after ACDF cannot be duplicated for CDA. For patients undergoing CDA, during extreme flexion/extension or rotation, the exiting nerve roots might be impinged by inadequately decompressed foraminal osteophytes. Therefore, the authors advocate generous decompression, including resection of the posterior longitudinal ligament (PLL) and bilateral uncovertebral joints (UVJs), even in the asymptomatic side. This video demonstrates full dural expansion and enlarged neuroforamen after removal of the PLL and UVJs. Venous hemorrhage encountered during foraminotomy can always be controlled by cottonoid packing or hemostatic agents. Also, the endplates of the surrounding vertebral bodies were meticulously prepared for parallel insertion of the ProDisc-C Nova (DePuy Synthes Spine) artificial disc. Please note that the ProDisc-C Nova is currently not available on the US market.

The video can be found here: https://youtu.be/XUo34j6WFYs.

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John E. Ziewacz, Sigurd H. Berven, Valli P. Mummaneni, Tsung-Hsi Tu, Olaolu C. Akinbo, Russ Lyon and Praveen V. Mummaneni

Object

The purpose of this study was to provide an evidence-based algorithm for the design, development, and implementation of a new checklist for the response to an intraoperative neuromonitoring alert during spine surgery.

Methods

The aviation and surgical literature was surveyed for evidence of successful checklist design, development, and implementation. The limitations of checklists and the barriers to their implementation were reviewed. Based on this review, an algorithm for neurosurgical checklist creation and implementation was developed. Using this algorithm, a multidisciplinary team surveyed the literature for the best practices for how to respond to an intraoperative neuromonitoring alert. All stakeholders then reviewed the evidence and came to consensus regarding items for inclusion in the checklist.

Results

A checklist for responding to an intraoperative neuromonitoring alert was devised. It highlights the specific roles of the anesthesiologist, surgeon, and neuromonitoring personnel and encourages communication between teams. It focuses on the items critical for identifying and correcting reversible causes of neuromonitoring alerts. Following initial design, the checklist draft was reviewed and amended with stakeholder input. The checklist was then evaluated in a small-scale trial and revised based on usability and feasibility.

Conclusions

The authors have developed an evidence-based algorithm for the design, development, and implementation of checklists in neurosurgery and have used this algorithm to devise a checklist for responding to intraoperative neuromonitoring alerts in spine surgery.

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Jau-Ching Wu, Wen-Cheng Huang, Hsiao-Wen Tsai, Chin-Chu Ko, Ching-Lan Wu, Tsung-Hsi Tu and Henrich Cheng

Object

The long-term outcome of lumbar dynamic stabilization is uncertain. This study aimed to investigate the incidence, risk factors, and outcomes associated with screw loosening in a dynamic stabilization system.

Methods

The authors conducted a retrospective review of medical records, radiological studies, and clinical evaluations obtained in consecutive patients who underwent 1- or 2-level lumbar dynamic stabilization and were followed up for more than 24 months. Loosening of screws was determined on radiography and CT scanning. Radiographic and standardized clinical outcomes, including the visual analog scale (VAS) and Oswestry Disability Index (ODI) scores, were analyzed with a focus on cases in which screw loosening occurred.

Results

The authors analyzed 658 screws in 126 patients, including 54 women (42.9%) and 72 men (57.1%) (mean age 60.4 ± 11.8 years). During the mean clinical follow-up period of 37.0 ± 7.1 months, 31 screws (4.7%) in 25 patients (19.8%) were shown to have loosened. The mean age of patients with screw loosening was significantly higher than those without loosening (64.8 ± 8.8 vs 59.3 ± 12.2, respectively; p = 0.036). Patients with diabetes mellitus had a significantly higher rate of screw loosening compared with those without diabetes (36.0% vs 15.8%, respectively; p = 0.024). Diabetic patients with well-controlled serum glucose (HbA1c ≤ 8.0%) had a significantly lower chance of screw loosening than those without well-controlled serum glucose (28.6% vs 71.4%, respectively; p = 0.021). Of the 25 patients with screw loosening, 22 cases (88%) were identified within 6.6 months of surgery; 18 patients (72%) had the loosened screws in the inferior portion of the spinal construct, whereas 7 (28%) had screw loosening in the superior portion of the construct. The overall clinical outcomes at 3, 12, and 24 months, measured by VAS for back pain, VAS for leg pain, and ODI scores, were significantly improved after surgery compared with before surgery (all p < 0.05). There were no significant differences between the patients with and without screw loosening at all evaluation time points (all p > 0.05). All 25 patients with screw loosening were asymptomatic, and in 6 (24%) osseous integration was demonstrated on later follow-up. Also, there were 3 broken screws (2.38% in 126 patients or 0.46% in 658 screws). To date, none of these loosened or broken screws have required revision surgery.

Conclusions

Screw loosening in dynamic stabilization systems is not uncommon (4.7% screws in 19.8% patients). Patients of older age or those with diabetes have higher rates of screw loosening. Screw loosening can be asymptomatic and presents opportunity for osseous integration on later follow-up. Although adverse effects on clinical outcomes are rare, longer-term follow-up is required in cases in which screws become loose.

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Tsung-Hsi Tu, Jau-Ching Wu, Wen-Cheng Huang, Ching-Lan Wu, Chin-Chu Ko and Henrich Cheng

Object

Heterotopic ossification (HO) after cervical arthroplasty can limit the mobility of an artificial disc. In this study the authors used CT scanning to assess the formation of HO with the goal of investigating the correlation between the carpentry of arthroplasty, formation of HO, mobility, and clinical outcomes.

Methods

A retrospective review of medical records, radiological studies, and clinical evaluations was conducted for consecutive patients who underwent 1- or 2-level cervical arthroplasty with the Bryan disc. The patients underwent follow-up for more than 24 months. The formation of HO was assessed using CT scanning as the final determination. The perfectness of carpentry for each arthroplasty level was scrutinized using criteria composed of 2 parameters (postoperative shell kyphosis and inadequate endplate coverage). Levels were divided into the optimal carpentry group and the suboptimal carpentry group. Radiographic and clinical outcomes, including the visual analog scale and neck disability index, were compared between the groups.

Results

A total of 107 levels of Bryan discs were placed in 75 patients (mean age 46.71 ± 9.94 years) and were analyzed. There was a male predominance of 68.0% (51 men), and the mean follow-up duration was 38.56 ± 9.66 months. Heterotopic ossification was identified in 60 levels (56.1%) by CT scanning. Most cases of HO were low grade and did not correlate with the limitation in the segmental motion of the arthroplasty device. There were no significant differences in terms of age, sex, and number of arthroplasty levels between the optimal and the suboptimal carpentry groups. However, the suboptimal carpentry group had significantly more high-grade HO (≥ Grade 2) than the optimal carpentry group (13 levels [12.1%] vs 7 levels [6.5%], p = 0.027). There were also more immobile (range of motion < 3°) artificial discs in the suboptimal carpentry group than the optimal carpentry group (11 levels [10.3%] vs 4 levels [3.7%], p = 0.010). The clinical outcomes (neck and arm visual analog scale scores and Neck Disability Index) in both groups were similarly good.

Conclusions

Shell kyphosis and inadequate endplate coverage have adverse effects on the formation of HO and segmental mobility after cervical arthroplasty with the Bryan artificial disc. Appropriate carpentry is the more important factor in determining the maintenance of segmental motion. Although the midterm clinical outcome remained similarly good regardless of HO, the carpentry of cervical arthroplasty should not be overlooked. Further studies are needed to clarify the etiology of HO.

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Cheng-Wei Huang, Hsien-Tang Tu, Chun-Yi Chuang, Cheng-Siu Chang, Hsi-Hsien Chou, Ming-Tsung Lee and Chuan-Fu Huang

OBJECTIVE

Stereotactic radiosurgery (SRS) is an important alternative management option for patients with small- and medium-sized vestibular schwannomas (VSs). Its use in the treatment of large tumors, however, is still being debated. The authors reviewed their recent experience to assess the potential role of SRS in larger-sized VSs.

METHODS

Between 2000 and 2014, 35 patients with large VSs, defined as having both a single dimension > 3 cm and a volume > 10 cm3, underwent Gamma Knife radiosurgery (GKRS). Nine patients (25.7%) had previously undergone resection. The median total volume covered in this group of patients was 14.8 cm3 (range 10.3–24.5 cm3). The median tumor margin dose was 11 Gy (range 10–12 Gy).

RESULTS

The median follow-up duration was 48 months (range 6–156 months). All 35 patients had regular MRI follow-up examinations. Twenty tumors (57.1%) had a volume reduction of greater than 50%, 5 (14.3%) had a volume reduction of 15%–50%, 5 (14.3%) were stable in size (volume change < 15%), and 5 (14.3%) had larger volumes (all of these lesions were eventually resected). Four patients (11.4%) underwent resection within 9 months to 6 years because of progressive symptoms. One patient (2.9%) had open surgery for new-onset intractable trigeminal neuralgia at 48 months after GKRS. Two patients (5.7%) who developed a symptomatic cyst underwent placement of a cystoperitoneal shunt. Eight (66%) of 12 patients with pre-GKRS trigeminal sensory dysfunction had hypoesthesia relief. One hemifacial spasm completely resolved 3 years after treatment. Seven patients with facial weakness experienced no deterioration after GKRS. Two of 3 patients with serviceable hearing before GKRS deteriorated while 1 patient retained the same level of hearing. Two patients improved from severe hearing loss to pure tone audiometry less than 50 dB.

The authors found borderline statistical significance for post-GKRS tumor enlargement for later resection (p = 0.05, HR 9.97, CI 0.99–100.00). A tumor volume ≥ 15 cm3 was a significant factor predictive of GKRS failure (p = 0.005). No difference in outcome was observed based on indication for GKRS (p = 0.0761).

CONCLUSIONS

Although microsurgical resection remains the primary management choice in patients with VSs, most VSs that are defined as having both a single dimension > 3 cm and a volume > 10 cm3 and tolerable mass effect can be managed satisfactorily with GKRS. Tumor volume ≥ 15 cm3 is a significant factor predicting poor tumor control following GKRS.