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Yeou-Chih Wang, Ming-Hsi Sun, Chi-Wen Lin, and Yen-Ju Chen

Object. Bilateral subaxillary transthoracic endoscopic sympathectomy (TES) is a popular procedure of upper thoracic sympathectomy. The anatomical locations of the T-2 and T-3 sympathetic trunks, as viewed under the endoscope, are varied in the rib head areas. In this study, the authors investigated the more visible anatomical locations of the T-2 and T-3 sympathetic trunks, the so-called nerves of Kuntz, and intercostal rami by performing transthoracic endoscopy.

Methods. Seventy patients with palmar hyperhidrosis undergoing bilateral TES (140 sides) via the anterior subaxillary approach were included in this study. The operative findings and video images of the T-2 and T-3 sympathetic trunks and ganglia were recorded and analyzed. The anatomical locations of the T-2 and T-3 sympathetic trunks along the horizontal axes of the rib heads were determined using a three-region system constructed by the authors. The area between the rib neck and the medial border of the rib head was equally divided into Region E (external half) and Region M (medial half). The area between the medial border of the rib head and the paravertebral ligament was defined as Region I.

The incidence of the T-2 and T-3 sympathetic trunks found in Regions E, M, and I were 31.4 to 42.9%, 50 to 57.1%, and 7.1 to 11.4%, respectively, on the left side, and 24.3 to 34.3%, 57.1 to 65.7%, and 8.6 to 10%, respectively, on the right side. One right (1.4%) and six left (8.6%) Kuntz nerves originating from the T-3 sympathetic trunk were found in seven patients (10%). The intercostal ramus was found around the T-2 rib neck in 24 patients (34.3%), with 18 cases (25.7%) for each side. The intercostal ramus around the T-3 rib neck was found in 17 patients (24.3%): 12 (17.1%) on the right and nine (12.9%) on the left.

Conclusions. These results indicate that approximately 90% of the T-2 or T-3 sympathetic trunks are located on the rib head. These findings may also be used to assist the surgeon in fluoroscopic guidance for locating the T-2 and T-3 sympathetic trunks during posterior percutaneous sympathectomy.

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Qi Wang, Chi Wang, Xiaobo Zhang, Fanqi Hu, Wenhao Hu, Teng Li, Yan Wang, and Xuesong Zhang

OBJECTIVE

The aim of this study was to investigate whether bone mineral density (BMD) measured in Hounsfield units (HUs) is correlated with proximal junctional failure (PJF).

METHODS

A retrospective study of 104 patients with adult degenerative lumbar disease was performed. All patients underwent posterior instrumented fusion of 4 or more segments and were followed up for at least 2 years. Patients were divided into two groups on the basis of whether they had mechanical complications of PJF. Age, sex ratio, BMI, follow-up time, upper instrumented vertebra (UIV), lower instrumented vertebra, and vertebral body osteotomy were recorded. The spinopelvic parameters were measured on early postoperative radiographs. The HU value of L1 trabecular attenuation was measured on axial and sagittal CT scans. Statistical analysis was performed to compare the difference of continuous and categorical variables. Receiver operating characteristic (ROC) curve analysis was used to obtain attenuation thresholds. A Kaplan-Meier curve and log-rank test were used to analyze the differences in PJF-free survival. Multivariate analysis via a Cox proportional hazards model was used to analyze the risk factors.

RESULTS

The HU value of L1 trabecular attenuation in the PJF group was lower than that in the control group (p < 0.001). The spinopelvic parameter L4–S1 lordosis was significantly different between the groups (p = 0.033). ROC curve analysis determined an optimal threshold of 89.25 HUs (sensitivity = 78.3%, specificity = 80.2%, area under the ROC curve = 0.799). PJF-free survival significantly decreased in patients with L1 attenuation ≤ 89.25 HUs (p < 0.001, log-rank test). When L1 trabecular attenuation was ≤ 89.25 HUs, PJF-free survival in patients with the UIV at L2 was the lowest, compared with patients with their UIV at the thoracolumbar junction or above (p = 0.028, log-rank test).

CONCLUSIONS

HUs could provide important information for surgeons to make a treatment plan to prevent PJF. L1 trabecular attenuation ≤ 89.25 HUs measured by spinal CT scanning could predict the incidence of PJF. Under this condition, the UIV at L2 significantly increases the incidence of PJF.

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Xiang-Yang Wang, Li-Yang Dai, Hua-Zi Xu, and Yong-Long Chi

Object.

Experimental burst fracture models are often developed by using either single or incremental impacts. In both protocols, the weight-drop technique produces the impact. However, to the authors' knowledge in no study have researchers attempted to compare the equivalence of the spine burst fracture produced using the different impact protocols. This study was performed to investigate whether the single and incremental trauma approaches produce equivalent degrees of severity in thoracolumbar burst fractures.

Methods.

Twenty bovine thoracolumbar spines comprising three vertebrae were divided evenly into the single impact and incremental impact groups. The specimens in the incremental impact group were subjected to three axial compressive impacts of increasing energy (78.4, 107.8, and 137.2 J), whereas specimens in the other group were subjected to a single impact (137.2 J). Before and after the final trauma, multidirectional flexibility of each specimen was measured under flexion/extension, right/left lateral bending, and right/left axial rotation, thus quantifying the instability of the fracture. The flexibility parameters were then compared between the two groups.

Results.

A significant increase in flexibility parameters was found after the final trauma in both groups, indicating the instability of the spine (p < 0.01). No significant differences in flexibility parameters were observed in either intact status or injured status between the two groups (p > 0.05).

Conclusions.

In this study the authors have confirmed that the single and incremental impact protocols produced a similar degree of severity in producing an in vitro bovine burst fracture. The results of this study support the use of the incremental impact protocol in future experimental biomechanical studies.

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Xiang-Yang Wang, Li-Yang Dai, Hua-Zi Xu, and Yong-Long Chi

Object

Recurrent kyphosis has been commonly seen after posterior short-segment pedicle instrumentation for a thoracolumbar fracture, but studies on this issue are relatively scarce, and the clinical significance of recurrent deformity is uncertain. No study has addressed the associations between the reduction of a burst fracture vertebra and the final recurrent kyphosis after implant removal. The aim of this study was to investigate the recurrent kyphosis after short-segment pedicle screw fixation in thoracolumbar burst fractures and to evaluate the effect of the degree of a vertebral reduction on the recurrent kyphotic deformity after implant removal.

Methods

Twenty-seven patients who had undergone posterior short-segment pedicle screw fixation for thoracolumbar junction burst fractures (T12–L2) were investigated retrospectively. The minimum follow-up period was 2 years (mean 2.7 years). Pain status was evaluated using the Denis pain scale. Changes in the anterior vertebral height ratio, vertebral wedge angle, upper intervertebral angle, lower intervertebral angle, Cobb angle, regional angle, and sagittal index were measured preoperatively, postoperatively, before implant removal, and at final follow-up. The correlation between the reduction of a fractured vertebra and the recurrent kyphotic deformity was also analyzed.

Results

After the initial surgical correction, the reduced vertebral body (VB) height (anterior vertebral height ratio and vertebral wedge angle) remained stable until final follow-up, whereas the intervertebral disc space (the upper and lower intervertebral angles) collapsed, resulting in a progressive kyphotic deformity (Cobb angle, regional angle, and sagittal index). No significant correlation was found between the final kyphosis and pain scale, but the 8 patients with a sagittal index > 15° showed a higher incidence of moderate to severe pain (P3–5 on the Denis pain scale) compared with the remaining 19 patients with a sagittal index < 15°. Significant positive correlation was found between recurrent kyphosis and vertebral wedge angle (r = 0.850, p < 0.001) and the reduced vertebral height (r = −0.727, p < 0.001).

Conclusions

Given that the correction loss occurs primarily through disc space collapse, the amount of the final kyphotic deformity was predictable by the degree of the fractured vertebral reduction as seen on the lateral x-ray study. Surgeons who perform posterior reduction and fixation procedures should pay more attention to reducing the fractured vertebral wedge angle to its intact condition, rather than the segmental angular parameters. If the wedge angle of the fractured VB is unacceptable after reduction, additional reconstruction of the anterior column may be necessary.

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Wen-Yuh Chung, David Hung-Chi Pan, Cheng-Ying Shiau, Wan-Yuo Guo, and Ling-Wei Wang

Object. The goal of this study was to elucidate the role of gamma knife radiosurgery (GKS) and adjuvant stereotactic procedures by assessing the outcome of 31 consecutive patients harboring craniopharyngiomas treated between March 1993 and December 1999.

Methods. There were 31 consecutive patients with craniopharyngiomas: 18 were men and 13 were women. The mean age was 32 years (range 3–69 years). The mean tumor volume was 9 cm3 (range 0.3–28 cm3). The prescription dose to the tumor margin varied from 9.5 to 16 Gy. The visual pathways received 8 Gy or less. Three patients underwent stereotactic aspiration to decompress the cystic component before GKS. The tumor response was classified by percentage reduction of tumor volume as calculated based on magnetic resonance imaging studies. Clinical outcome was evaluated according to improvement and dependence on replacement therapy.

An initial postoperative volume increase with enlargement of a cystic component was found in three patients. They were treated by adjuvant stereotactic aspiration and/or Ommaya reservoir implantation. Tumor control was achieved in 87% of patients and 84% had fair to excellent clinical outcome in an average follow-up period of 36 months. Treatment failure due to uncontrolled tumor progression was seen in four patients at 26, 33, 49, and 55 months, respectively, after GKS. Only one patient was found to have a mildly restricted visual field; no additional endocrinological impairment or neurological deterioration could be attributed to the treatment. There was no treatment-related mortality.

Conclusions. Multimodality management of patients with craniopharyngiomas seemed to provide a better quality of patient survival and greater long-term tumor control. It is suggested that GKS accompanied by adjuvant stereotactic procedures should be used as an alternative in treating recurrent or residual craniopharyngiomas if further microsurgical excision cannot promise a cure.

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I-Chang Su, Chi-Cheng Yang, Wei-Han Wang, Jing-Er Lee, Yong-Kwang Tu, and Kuo-Chuan Wang

The authors present a rare case of an infarction complication 15 days following acute intraventricular bleeding due to moyamoya disease. Before the infarction occurred, perfusion CT imaging disclosed early but reversible ischemic injury on the day of hemorrhage. Dehydration and hypotension are both possibly contributing factors of progressive injury from reversible ischemia due to infarction. Although the patient underwent successful bypass surgery, 1 month after the ictus the neurobehavior evaluation still showed marked executive dysfunction. The authors address that, in hemorrhagic-type moyamoya disease, early perfusion CT scanning is not only a powerful tool to identify the high-risk group of patients who could experience subacute infarction, but also alarms neurosurgeons to eliminate any predisposing factors when it shows reversible ischemic injuries.

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D. Hung-Chi Pan, Wan-Yuo Guo, Wen-Yuh Chung, Cheng-Ying Shiau, Yue-Cune Chang, and Ling-Wei Wang

Object. A consecutive series of 240 patients with arteriovenous malformations (AVMs) treated by gamma knife radiosurgery (GKS) between March 1993 and March 1999 was evaluated to assess the efficacy and safety of radiosurgery for cerebral AVMs larger than 10 cm3 in volume.

Methods. Seventy-six patients (32%) had AVM nidus volumes of more than 10 cm3. During radiosurgery, targeting and delineation of AVM nidi were based on integrated stereotactic magnetic resonance (MR) imaging and x-ray angiography. The radiation treatment was performed using multiple small isocenters to improve conformity of the treatment volume. The mean dose inside the nidus was kept between 20 Gy and 24 Gy. The margin dose ranged between 15 to 18 Gy placed at the 55 to 60% isodose centers. Follow up ranged from 12 to 73 months.

There was complete obliteration in 24 patients with an AVM volume of more than 10 cm3 and in 91 patients with an AVM volume of less than 10 cm3. The latency for complete obliteration in larger-volume AVMs was significantly longer. In Kaplan—Meier analysis, the complete obliteration rate in 40 months was 77% in AVMs with volumes between 10 to 15 cm3, as compared with 25% for AVMs with a volume of more than 15 cm3. In the latter, the obliteration rate had increased to 58% at 50 months. The follow-up MR images revealed that large-volume AVMs had higher incidences of postradiosurgical edema, petechiae, and hemorrhage. The bleeding rate before cure was 9.2% (seven of 76) for AVMs with a volume exceeding 10 cm3, and 1.8% (three of 164) for AVMs with a volume less than 10 cm3. Although focal edema was more frequently found in large AVMs, most of the cases were reversible. Permanent neurological complications were found in 3.9% (three of 76) of the patients with an AVM volume of more than 10 cm3, 3.8% (three of 80) of those with AVM volume of 3 to 10 cm3, and 2.4% (two of 84) of those with an AVM volume less than 3 cm3. These differences in complications rate were not significant.

Conclusions. Recent improvement of radiosurgery in conjunction with stereotactic MR targeting and multiplanar dose planning has permitted the treatment of larger AVMs. It is suggested that gamma knife radiosurgery is effective for treating AVMs as large as 30 cm3 in volume with an acceptable risk.

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Kang-Du Liu, Wen-Yuh Chung, Hsiu-Mei Wu, Cheng-Ying Shiau, Ling-Wei Wang, Wan-You Guo, and David Hung-Chi Pan

Object. The authors sought to determine the value of gamma knife surgery (GKS) in the treatment of cavernous hemangiomas (CHs).

Methods. Between 1993 and 2002, a total of 125 patients with symptomatic CHs were treated with GKS. Ninety-seven patients presented with bleeding and 45 of these had at least two bleeding episodes. Thirteen patients presented with seizures combined with hemorrhage, and 15 patients presented with seizures alone. The mean margin dose of radiation was 12.1 Gy and the mean follow-up time was 5.4 years.

In the 112 patients who had bled the number of rebleeds after GKS was 32. These rebleeds were defined both clinically and based on magnetic resonance imaging for an annual rebleeding rate of 32 episodes/492 patient-years or 6.5%. Twenty-three of the 32 rebleeding episodes occurred within 2 years after GKS. Nine episodes occurred after 2 years; thus, the annual rebleeding rate after GKS was 10.3% for the first 2 years and 3.3% thereafter (p = 0.0038). In the 45 patients with at least two bleeding episodes before GKS, the rebleeding rate dropped from 29.2% (55 episodes/188 patient-years) before treatment to 5% (10 episodes/197 patient-years) after treatment (p < 0.0001). Among the 28 patients who presented with seizures, 15 (53%) had good outcomes (Engel Grades I and II). In this study of 125 patients, symptomatic radiation-induced complications developed in only three patients.

Conclusions. Gamma knife surgery can effectively reduce the rebleeding rate after the first symptomatic hemorrhage in patients with CH. In addition, GKS may be useful in reducing the severity of seizures in patients with CH.

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Chi Long Ho, Chee Meng Wang, Kah Keow Lee, Ivan Ng, and Beng Ti Ang

Object

This study addresses the changes in brain oxygenation, cerebrovascular reactivity, and cerebral neurochemistry in patients following decompressive craniectomy for the control of elevated intracranial pressure (ICP) after severe traumatic brain injury (TBI).

Methods

Sixteen consecutive patients with isolated TBI and elevated ICP, who were refractory to maximal medical therapy, underwent decompressive craniectomy over a 1-year period. Thirteen patients were male and 3 were female. The mean age of the patients was 38 years and the median Glasgow Coma Scale score on admission was 5.

Results

Six months following TBI, 11 patients had a poor outcome (Group 1, Glasgow Outcome Scale [GOS] Score 1–3), whereas the remaining 5 patients had a favorable outcome (Group 2, GOS Score 4 or 5). Decompressive craniectomy resulted in a significant reduction (p < 0.001) in the mean ICP and cerebrovascular pressure reactivity index to autoregulatory values (< 0.3) in both groups of patients. There was a significant improvement in brain tissue oxygenation (PbtO2) in Group 2 patients from 3 to 17 mm Hg and an 85% reduction in episodes of cerebral ischemia. In addition, the durations of abnormal PbtO2 and biochemical indices were significantly reduced in Group 2 patients after decompressive craniectomy, but there was no improvement in the biochemical indices in Group 1 patients despite surgery.

Conclusions

Decompressive craniectomy, when used appropriately in protocol-driven intensive care regimens for the treatment of recalcitrant elevated ICP, is associated with a return of abnormal metabolic parameters to normal values in patients with eventually favorable outcomes.