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Jae-Sung Ahn, Ho-Jin Lee, Dae-Jung Choi, Ki-young Lee and Sung-jin Hwang

This study was performed to describe the extraforaminal approach of biportal endoscopic spinal surgery (BESS) as a new endoscopic technique for transforaminal decompression and discectomy and to demonstrate the clinical outcomes of this new procedure for the first time. Twenty-one patients (27 segments) who underwent the extraforaminal approach of BESS between March 2015 and April 2016 were enrolled according to the inclusion and exclusion criteria. The operative time (minutes/level) and complications after the procedure were recorded. The visual analog scale (VAS) score was checked to assess the degree of radicular leg pain preoperatively and at the time of the last follow-up. The modified Macnab criteria were used to examine the clinical outcomes at the time of the last follow-up. The mean duration of the follow-up period was 14.8 months (minimum duration 12 months). The mean operative time was 96.7 minutes for one level. The mean VAS score for radicular leg pain dropped from a preoperative score of 7.5 ± 0.9 to a final follow-up score of 2.5 ± 1.2 (p < 0.001). The final outcome according to the modified Macnab criteria was excellent in 5 patients (23.8%), good in 12 (57.2%), fair in 4 (19.0%), and poor in 0. Therefore, excellent or good results (a satisfied outcome) were obtained in 80.9% of the patients. Complications were limited to one dural tear (4.8%). The authors found that the extraforaminal approach of BESS was a feasible and advantageous endoscopic technique for the treatment of foraminal lesions, including stenosis and disc herniation. They suggest that this technique represents a useful, alternative, minimally invasive method that can be used to treat lumbar foraminal stenosis and disc herniation.

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Dong-Kyu Jang, Kwan-Sung Lee, Hyoung Kyun Rha, Pil-Woo Huh, Ji-Ho Yang, Ik Seong Park, Jae-Geun Ahn, Jae Hoon Sung and Young-Min Han

OBJECTIVE

In this study the authors evaluated whether extracranial-intracranial bypass surgery can prevent stroke occurrence and decrease mortality in adult patients with symptomatic moyamoya disease (MMD).

METHODS

The medical records of 249 consecutive adult patients with symptomatic MMD that was confirmed by digital subtraction angiography between 2002 and 2011 at 8 institutions were retrospectively reviewed. The study outcomes of stroke recurrence as a primary event and death during the 6-year follow-up and perioperative complications within 30 days as secondary events were compared between the bypass and medical treatment groups.

RESULTS

The bypass group comprised 158 (63.5%) patients, and the medical treatment group comprised 91 (36.5%) patients. For 249 adult patients with MMD, bypass surgery showed an HR of 0.48 (95% CI 0.27–0.86, p = 0.014) for stroke recurrence calculated by Cox regression analysis. However, for the 153 patients with ischemic MMD, the HR of bypass surgery for stroke recurrence was 1.07 (95% CI 0.43–2.66, p = 0.887). For the 96 patients with hemorrhagic MMD, the multivariable adjusted HR of bypass surgery for stroke recurrence was 0.18 (95% CI 0.06–0.49, p = 0.001). For the treatment modality, indirect bypass and direct bypass (or combined bypass) did not show any significant difference for stroke recurrence, perioperative stroke, or mortality (log rank; p = 0.524, p = 0.828, and p = 0.616, respectively).

CONCLUSIONS

During the treatment of symptomatic MMD in adults, bypass surgery reduces stroke recurrence for the hemorrhagic type, but it does not do so for the ischemic type. The best choice of bypass methods in adult patients with MMD is uncertain. In adult ischemic MMD, a prospective randomized study to evaluate the effectiveness and safety of bypass surgery to prevent recurrent stroke is necessary.

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Jung-Ho Yun, Do Hoon Kwon, Eun Jung Lee, Do Heui Lee, Jae Sung Ahn and Byung Duk Kwun

New nidi are rarely found adjacent to the resection margin following treatment for an arteriovenous malformation (AVM), especially in adults. In addition, there are no reports in adults of new nidus formation adjacent to the targeted site of an AVM that angiography has verified to be completely obliterated by radiosurgery. The authors present their experience with recurrent AVMs following AVM radiosurgery in 3 patients whose ages were 9 years, 10 years, and 33 years. None of the patients had been treated with embolization before radiosurgery. Two patients had a history of intracerebral hemorrhage before radiosurgery. New lesions developed around the obliterated nidi in all 3 cases. Angiography performed after the first radiosurgery confirmed complete removal of the nidus in all 3 patients, and new nidus formation was detected 31, 132, and 36 months after the initial GKS. The new lesions were also treated by GKS. Occasionally, in patients with recurrent AVMs, such as those described in this paper, long-term clinical and angiographic follow-up may be required, even if complete occlusion is originally shown on angiograms.

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Jung Cheol Park, Deok Hee Lee, Jae Kyun Kim, Jae Sung Ahn, Byung Duk Kwun, Dae Yoon Kim and Choong Gon Choi

OBJECT

The incidence and risk factors of microembolic lesions on MR diffusion-weighted imaging (DWI) were analyzed after the endovascular coiling of unruptured intracranial aneurysms (UIAs).

METHODS

Data obtained from 271 consecutive patients (70 men and 201 women; median age 57 years; range 23–79 years) who presented with UIA for coil embolization between July 2011 and June 2013 were analyzed. Two independent reviewers examined the DWI and apparent diffusion coefficient maps obtained the following day for the presence of restrictive diffusion spots and counted the number of spots. Multivariate analysis was then performed to identify independent risk factors for developing microembolism following the coiling of an aneurysm.

RESULTS

Microembolic lesions were noted in 101 of 271 patients (37.3%). The results of the multivariate analysis showed that the following factors significantly influenced the risk for microembolism: age, diabetes, previous history of ischemic stroke, high-signal FLAIR lesions in the white matter, multiple aneurysms, and the insertion of an Enterprise stent (all ORs > 1.0 and all p values < 0.05). Previously known risk factors such as prolonged procedure duration, aneurysm size, and decreased antiplatelet function did not show any significant influence.

CONCLUSIONS

The incidence of microembolism after endovascular coiling of UIA was not low. Lesions occurred more frequently in patients with vascular status associated with old age, diabetes, and previous stroke. Aneurysm multiplicity and the type of stent used for treatment also influenced lesion occurrence.

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Eun-Hee Kim, Mi-Sun Yum, Young-Shin Ra, Jun Bum Park, Jae Sung Ahn, Gu-Hwan Kim, Hyun Woo Goo, Tae-Sung Ko and Han-Wook Yoo

OBJECT

Moyamoya disease (MMD) is an idiopathic cerebrovascular occlusive disorder prevalent in East Asia. In the pathogenesis of MMD, the important role of genetic factors is being elucidated, and RNF213 has recently been identified as a susceptibility gene for MMD. The aim of this retrospective study was to investigate the RNF213 genotype in patients with MMD and to determine their genotype-phenotype associations.

METHODS

The study involved 165 Korean MMD patients from 155 unrelated families who were diagnosed with MMD at a single center from 1995 to 2013. Their demographic, radiological, and clinical findings were evaluated. Direct sequencing of the major RNF213 single nucleotide polymorphisms was performed. The association of the common RNF213 variant with MMD risk was evaluated using historical controls for comparison. Correlations between RNF213 genotype and phenotype were statistically analyzed.

RESULTS

The c.14429G>A (p.R4810K) variant was identified in 125 (75.8%) of 165 MMD patients. Most patients (112) were heterozygous, and 13 patients had 2 copies of the c.14429G>A variant. A novel heterozygous variant, c.12086A>G (p.Q4029R), was found in 1 additional patient. The minor allele frequency of the c.14429G>A variant was significantly higher in the MMD group (138 [41.8%] of 330 patients) than in the control group (8 [1.36%] of 588 subjects; p < 0.001). The c.14429G>A (p.R4810K) variant significantly increased the risk of MMD in Korean patients, with an OR of 52.11 (p < 0.001) compared with controls. Moreover, c.14429G>A (p.R4810K) genotypes occurred more frequently in patients with a family history of MMD. The homozygous variant was highly associated with early-onset MMD (age at onset < 5 years), cerebral infarction at diagnosis, and cognitive impairment in long-term outcome.

CONCLUSIONS

The findings indicate that the c.14429G>A (p.R4810K) allele of RNF213 is strongly associated with Korean patients with MMD. The homozygous c.14429G>A (p.R4810K) variant is particularly related to early-onset MMD, severe symptomatic manifestations at diagnosis, and poor prognosis. This genotypic variant may be a useful biomarker for early-onset MMD or unstable MMD with cerebral infarction, which requires early diagnosis and revascularization treatment.

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Hae-Won Koo, Wonhyoung Park, Kuhyun Yang, Jung Cheol Park, Jae Sung Ahn, Sun Uck Kwon, Changmo Hwang and Deok Hee Lee

Although extremely rare, retention of foreign bodies such as microcatheters or micro guidewires can occur during various neurovascular procedures due to gluing of the microcatheter tip or entanglement of the micro guidewire tip with intravascular devices. The authors have experienced 2 cases of irresolvable wire retention, one after flow diverter placement for a left cavernous internal carotid artery aneurysm and the other after intracranial stenting for acute basilar artery occlusion. The first patient presented 6 weeks after her procedure with right lung parenchymal hemorrhage due to direct piercing of the lung parenchyma after the retained wire fractured and migrated out of the aortic arch. The second patient presented 4 years after his procedure with pneumothorax due to migration of the fractured guidewire segment into the right thoracic cavity. In this report, the authors discuss the possible mechanisms of these unusual complications and how to prevent delayed consequences from a retained intravascular metallic wire.

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Chang-Hyun Lee, Tae-Ahn Jahng, Seung-Jae Hyun, Chi Heon Kim, Sung-Bae Park, Ki-Jeong Kim, Chun Kee Chung, Hyun-Jib Kim and Soo-Eon Lee

OBJECTIVE

The Dynesys, a pedicle-based dynamic stabilization (PDS) system, was introduced to overcome the drawbacks of fusion procedures. Nevertheless, the theoretical advantages of PDS over fusion have not been clearly confirmed. The aim of this study was to compare clinical and radiological outcomes of patients who underwent PDS using the Dynesys system with those who underwent posterior lumbar interbody fusion (PLIF).

METHODS

The authors searched PubMed, Embase, Web of Science, and the Cochrane Database. Studies that reported outcomes of patients who underwent PDS or PLIF for the treatment of degenerative lumbar spinal disease were included. The primary efficacy end points were perioperative outcomes. The secondary efficacy end points were changes in the Oswestry Disability Index (ODI) and back and leg pain visual analog scale (VAS) scores and in range of motion (ROM) at the treated and adjacent segments. A meta-analysis was performed to calculate weighted mean differences (WMDs), 95% confidence intervals, Q statistics, and I2 values. Forest plots were constructed for each analysis group.

RESULTS

Of the 274 retrieved articles, 7 (which involved 506 participants [Dynesys, 250; PLIF, 256]) met the inclusion criteria. The Dynesys group showed a competitive advantage in mean surgery duration (20.73 minutes, 95% CI 8.76–32.70 minutes), blood loss (81.87 ml, 95% CI 45.11–118.63 ml), and length of hospital stay (1.32 days, 95% CI 0.23–2.41 days). Both the Dynesys and PLIF groups experienced improved ODI and VAS scores after 2 years of follow-up. Regarding the ODI and VAS scores, no statistically significant difference was noted according to surgical procedure (ODI: WMD 0.12, 95% CI −3.48 to 3.72; back pain VAS score: WMD −0.15; 95% CI −0.56 to 0.26; leg pain VAS score: WMD −0.07; 95% CI −0.47 to 0.32). The mean ROM at the adjacent segment increased in both groups, and there was no substantial difference between them (WMD 1.13; 95% CI −0.33 to 2.59). Although the United States is the biggest market for Dynesys, no eligible study from the United States was found, and 4 of 8 enrolled studies were performed in China. The results must be interpreted with caution because of publication bias. During Dynesys implantation, surgeons have to decide the length of the spacer and cord pretension. These values are debatable and can vary according to the surgeon's experience and the patient's condition. Differences between the surgical procedures were not considered in this study.

CONCLUSIONS

Fusion still remains the method of choice for advanced degeneration and gross instability. However, spinal degenerative disease with or without Grade I spondylolisthesis, particularly in patients who require a quicker recovery, will likely constitute the main indication for PDS using the Dynesys system.

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Yang Kwon, Jae Sung Ahn, Sang Ryong Jeon, Jeong Hoon Kim, Chang Jin Kim, Jung Kyo Lee, Byung Duk Kwun, Do Hee Lee and Sun Young Kim

Object. The authors evaluated whether gamma knife radiosurgery (GKS) could be a causative factor in intratumoral bleeding in meningiomas.

Methods. Gamma knife radiosurgery was used in the treatment of 173 meningiomas during a 10-year period. Four patients suffered post-GKS intratumoral hemorrhage. The course in these patients was reviewed.

Four of 173 patients suffered an intratumoral hemorrhage during a follow-up period of 1 to 8 years. The risk of intratumoral bleeding after GKS for meningioma was 2.3%. Intracystic hemorrhage occurred in two patients 1 and 5 years, respectively, after radiosurgery. In the other two cases intratumoral bleeding occurred 2 and 8 years, respectively, after radiosurgery. Histological examination in three cases found no specific findings related to the postradiosurgical changes.

Conclusions. Because the reported risk of spontaneous intratumoral bleeding in meningiomas is 1.3 to 2.7%, the incidence in this series was not unduly high. Radiosurgery itself could not be shown to be a significant factor in the development of the intratumoral bleeding.

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Yang Kwon, Jun Seok Bae, Jae Myung Kim, Do Hee Lee, Soon Young Kim, Jae Sung Ahn, Jeong Hoon Kim, Chang Jin Kim, Byung Duk Kwun and Jung Kyo Lee

✓ Tumors involving the optic nerve (optic glioma, optic nerve sheath meningioma) are benign but difficult to treat. Gamma knife surgery (GKS) may be a useful treatment. The authors present data obtained in three such cases and record the effects of GKS.

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Jaewoo Chung, Wonhyoung Park, Seok Ho Hong, Jung Cheol Park, Jae Sung Ahn, Byung Duk Kwun, Sang-Ahm Lee, Sung-Hoon Kim and Ji-Ye Jeon

OBJECTIVE

Somatosensory and motor evoked potentials (SEPs and MEPs) are often used to prevent ischemic complications during aneurysm surgeries. However, surgeons often encounter cases with suspicious false-positive and false-negative results from intraoperative evoked potential (EP) monitoring, but the incidence and possible causes for these results are not well established. The aim of this study was to investigate the efficacy and reliability of EP monitoring in the microsurgical treatment of intracranial aneurysms by evaluating false-positive and false-negative cases.

METHODS

From January 2012 to April 2016, 1514 patients underwent surgery for unruptured intracranial aneurysms (UIAs) with EP monitoring at the authors’ institution. An EP amplitude decrease of 50% or greater compared with the baseline amplitude was defined as a significant EP change. Correlations between immediate postoperative motor weakness and EP monitoring results were retrospectively reviewed. The authors calculated the sensitivity, specificity, and positive and negative predictive values of intraoperative MEP monitoring, as well as the incidence of false-positive and false-negative results.

RESULTS

Eighteen (1.19%) of the 1514 patients had a symptomatic infarction, and 4 (0.26%) had a symptomatic hemorrhage. A total of 15 patients showed motor weakness, with the weakness detected on the immediate postoperative motor function test in 10 of these cases. Fifteen false-positive cases (0.99%) and 8 false-negative cases (0.53%) were reported. Therefore, MEP during UIA surgery resulted in a sensitivity of 0.10, specificity of 0.94, positive predictive value of 0.01, and negative predictive value of 0.99.

CONCLUSIONS

Intraoperative EP monitoring has high specificity and negative predictive value. Both false-positive and false-negative findings were present. However, it is likely that a more meticulously designed protocol will make EP monitoring a better surrogate indicator of possible ischemic neurological deficits.