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Myung Ji Kim, So Hee Park, Kyung Won Chang, Yuhee Kim, Jing Gao, Maya Kovalevsky, Itay Rachmilevitch, Eyal Zadicario, Won Seok Chang, Hyun Ho Jung, and Jin Woo Chang

OBJECTIVE

Magnetic resonance imaging–guided focused ultrasound (MRgFUS) provides real-time monitoring of patients to assess tremor control and document any adverse effects. MRgFUS of the ventral intermediate nucleus (VIM) of the thalamus has become an effective treatment option for medically intractable essential tremor (ET). The aim of this study was to analyze the correlations of clinical and technical parameters with 12-month outcomes after unilateral MRgFUS thalamotomy for ET to help guide future clinical treatments.

METHODS

From October 2013 to January 2019, data on unilateral MRgFUS thalamotomy from the original pivotal study and continued-access studies from three different geographic regions were collected. Authors of the present study retrospectively reviewed those data and evaluated the efficacy of the procedure on the basis of improvement in the Clinical Rating Scale for Tremor (CRST) subscore at 1 year posttreatment. Safety was based on the rates of moderate and severe thalamotomy-related adverse events. Treatment outcomes in relation to various patient- and sonication-related parameters were analyzed in a large cohort of patients with ET.

RESULTS

In total, 250 patients were included in the present analysis. Improvement was sustained throughout the 12-month follow-up period, and 184 (73.6%) of 250 patients had minimal or no disability due to tremor (CRST subscore < 10) at the 12-month follow-up. Younger age and higher focal temperature (Tmax) correlated with tremor improvement in the multivariate analysis (OR 0.948, p = 0.013; OR 1.188, p = 0.025; respectively). However, no single statistically significant factor correlated with Tmax in the multivariate analysis. The cutoff value of Tmax in predicting a CRST subscore < 10 was 55.8°C. Skull density ratio (SDR) was positively correlated with heating efficiency (β = 0.005, p < 0.001), but no significant relationship with tremor improvement was observed. In the low-temperature group, 1–3 repetitions to the right target with 52°C ≤ Tmax ≤ 54°C was sufficient to generate sustained tremor suppression within the investigated follow-up period. The high-temperature group had a higher rate of balance disturbances than the low-temperature group (p = 0.04).

CONCLUSIONS

The authors analyzed the data of 250 patients with the aim of improving practices for patient screening and determining treatment endpoints. These results may improve the safety, efficacy, and efficiency of MRgFUS thalamotomy for ET.

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Chiman Jeon, Chang-Ki Hong, Kyung In Woo, Sang Duk Hong, Do-Hyun Nam, Jung-Il Lee, Jung Won Choi, Ho Jun Seol, and Doo-Sik Kong

OBJECTIVE

Tumors involving Meckel’s cave remain extremely challenging because of the surrounding complex neurovascular structures and deep-seated location. The authors investigated a new minimal-access technique using the endoscopic transorbital approach (eTOA) through the superior eyelid crease to Meckel’s cave and middle cranial fossa lesions and reviewed the most useful surgical procedures and pitfalls of this approach.

METHODS

Between September 2016 and January 2018, the authors performed eTOA in 9 patients with tumors involving Meckel’s cave and the middle cranial fossa. The lesions included trigeminal schwannoma in 4 patients, meningioma in 2 patients, metastatic brain tumor in 1 patient, chondrosarcoma in 1 patient, and dermoid cyst in 1 patient. In 7 of the 9 patients, eTOA alone was performed, while the other 2 patients underwent a combined eTOA and endoscopic endonasal approach or retrosigmoid craniotomy. Data including details of surgical techniques and clinical outcomes were recorded.

RESULTS

Gross-total resection was performed in 7 of the 9 patients (77.8%). Four patients underwent extended eTOA (with lateral orbital rim osteotomy). Drilling of the trapezoid sphenoid floor, a middle fossa “peeling” technique, and full visualization of Meckel’s cave were applied to approach the lesions. Tumors were exposed and removed extradurally in 3 patients and intradurally in 6 patients. There was no postoperative CSF leak.

CONCLUSIONS

The eTOA affords a direct route to access Meckel’s cave and middle cranial fossa lesions. With experience, this novel approach can be successfully applied to selected skull base lesions. To achieve successful removal of the tumor, emphasis should be placed on the importance of adequately removing the greater sphenoid wing and vertical crest. However, because of limited working space eTOA may not be an ideal approach for posterior fossa lesions.

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Young-Soo Kim, Ho-Yeol Zhang, Byung-Jin Moon, Kyung-Woo Park, Kyu-Yeul Ji, Won-Chang Lee, Kyu-Sung Oh, Gwon-Ui Ryu, and Daniel H. Kim

Object

The purpose of this study was to analyze the usefulness of the BioFlex, a Nitinol spring rod dynamic stabilization system, and the Nitinol shape memory loop (KIMPF-DI Fixing System) as a posterior dynamic stabilization system in surgery for low-back pain.

Methods

The 103 patients who underwent treatment with the BioFlex system were divided into two groups: Group 1, dynamic stabilization with or without posterior lumbar interbody fusion (PLIF); and Group 2, rigid fixation (PLIF + BioFlex system only). A total of 66 segments were treated with only the BioFlex system; in these the preoperative range of motion (ROM) was 10.0 ± 4.3°, which changed to 4.1 ± 1.9° after surgery. Adjacent-segment ROM changed from 8.4 ± 3.4° to 10.7 ± 3.2° in Group 1 and from 6.5 ± 3.2° to 10.5 ± 4.6° in Group 2 postoperatively. A total of 110 segments received both BioFlex and PLIF, with a fusion rate of 90.0%. The visual analog scale score for back pain improved from 7.3 ± 3.1 to 1.4 ± 1.8 in Group 1 and from 7.4 ± 2.4 to 2.1 ± 2.3 in Group 2. The Oswestry Disability Index improved from 35.2 ± 6.4 to 12.1 ± 4.5 in Group 1 and from 37.8 ± 5.7 to 13.6 ± 4.2 in Group 2. (The ROM and assessment scores expressed are the mean ± standard deviation.)

The 194 patients in whom Nitinol memory loops were implanted were analyzed based on the preoperative and 1-year postoperative ROM of each lumbar segment. The change of ROM in looped segments treated with PLIF was significantly reduced, but the change of ROM in looped segments without PLIF was not significant. The change of ROM at the segment adjacent to the loop was not significant, and the change of kyphosis reflected a slight recovery.

Conclusions

The Nitinol BioFlex dynamic stabilization system can achieve stabilization and simultaneously allow physiological movement, which can in turn decrease the degeneration of adjacent segments. When used with PLIF, the fusion rate can be expected to increase. The flexible Nitinol shape memory loop, a posterior dynamic stabilization device, is an adequate tension band that displays strength similar to the posterior ligamentous structures. In combination with PLIF at the main lesion, the BioFlex system or the Nitinol memory loop can provide posterior dynamic stabilization to the transitional upper or lower segments, enhance the fusion rate, reduce the adjacent-segment degeneration, and provide dynamic stabilization of the spine.

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Doo-Sik Kong, Stephanie Ming Young, Chang-Ki Hong, Yoon-Duck Kim, Sang Duk Hong, Jung Won Choi, Ho Jun Seol, Jung-Il Lee, Hyung Jin Shin, Do-Hyun Nam, and Kyung In Woo

OBJECTIVE

Cranioorbital tumors are complex lesions that involve the deep orbit, floor of the frontal bone, and lesser and greater wing of the sphenoid bone. The purpose of this study was to describe the clinical and ophthalmological outcomes with an endoscopic transorbital approach (TOA) in the management of cranioorbital tumors involving the deep orbit and intracranial compartment.

METHODS

The authors performed endoscopic TOAs via the superior eyelid crease incision in 18 patients (16 TOA alone and 2 TOA combined with a simultaneous endonasal endoscopic resection) with cranioorbital tumors from September 2016 to November 2017. There were 12 patients with sphenoorbital meningiomas. Other lesions included osteosarcoma, plasmacytoma, sebaceous gland carcinoma, intraconal schwannoma, cystic teratoma, and fibrous dysplasia. Ten patients had primary lesions and 8 patients had recurrent tumors. Thirteen patients had intradural lesions, while 5 had only extradural lesions.

RESULTS

Of 18 patients, 7 patients underwent gross-total resection of the tumor and 7 patients underwent planned near-total resection of the tumor, leaving the cavernous sinus lesion. Subtotal resection was performed in 4 patients with recurrent tumors. There was no postoperative CSF leak requiring reconstruction surgery. Fourteen of 18 patients (77.8%) had preoperative proptosis on the ipsilateral side, and all 14 patients had improvement in exophthalmos; the mean proptosis reduced from 5.7 ± 2.7 mm to 1.5 ± 1.4 mm. However, some residual proptosis was evident in 9 of the 14 (64%). Ten of 18 patients (55.6%) had preoperative optic neuropathy, and 6 of them (60.0%) had improvement; the median best-corrected visual acuity improved from 20/100 to 20/40. Thirteen of 18 patients showed mild ptosis at an immediate postoperative examination, all of whom had a spontaneous and complete recovery of their ptosis during the follow-up period. Three of 7 patients showed improvement in extraocular motility after surgery.

CONCLUSIONS

Endoscopic TOA can be considered as an option in the management of cranioorbital tumors involving complex anatomical areas, with acceptable sequelae and morbidity.