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Chih-Chen Chang, Hong-Shiu Chang, and Cheng Hong Toh

The authors report a case in which intravitreous silicone oil migrated into the ventricles. They note that intraventricular silicone oil can be misdiagnosed as intraventricular hemorrhage and neurosurgeons should be aware of this possibility.

This 58-year-old woman with a history of Type II diabetic mellitus and retinal detachment (resulting from diabetic retinopathy), which had been treated with intravitreous silicone tamponade, presented with dizziness and headache approximately 10 years after the intravitreous silicone treatment. Over the next 6 years she underwent 2 non–contrast-enhanced brain CT studies and 1 MRI study for evaluation of her symptoms. On CT scan, extension of the intraocular silicone along the optic nerve was evident. Two hyperdense nodules were observed freely floating in the right lateral and fourth ventricles, remaining in the nondependent portion of ventricles in both supine and prone positions. On T2-weighted MRI, the left orbital content and the intraventricular nodules all demonstrated chemical shift artifacts typically associated with silicone. The imaging findings were characteristic for intraventricular silicone after silicone oil tamponade. The patient's dizziness and headache were treated symptomatically and she was followed up at the outpatient department.

Migration of intravitreous silicone oil into the cerebral ventricles is a rare complication. Intraventricular silicone oil can mimic intraventricular hemorrhage. Radiographically, intraventricular silicone oil can be distinguished from hemorrhage as silicone oil tends to stay in the nondependent portion of the ventricle. Chemical shift artifacts on MRI may help establishing the diagnosis of intraventricular silicone oil. Currently, there is no consensus on surgical removal of intraventricular silicone oil, and in the majority of cases reported in the literature, the patients were asymptomatic.

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Chun-Hung Tseng, Wei-Shih Huang, Chih-Hsin Muo, Yen-Jung Chang, and Fung-Chang Sung

OBJECT

Inflammation may provoke cerebral arteriolar ectasia, inducing microaneurysm formation and further promoting intracerebral hemorrhage (ICH). Chronic osteomyelitis (COM) is an inflammatory disorder for which study of its role in ICH is lacking. This study explored whether COM increases the risk of ICH.

METHODS

From Taiwan national insurance inpatient claims, 22,052 patients who were newly diagnosed with COM between 1997 and 2010 were identified; 88, 207 age and sex frequency-matched subjects without COM were selected at random for comparison. Risks of ICH associated with COM and comorbidities, including hypertension, diabetes, hyperlipidemia, chronic kidney disease, and drug abuse, were assessed by the end of 2010.

RESULTS

The incidence of ICH was 1.68 times higher in the COM cohort than in the comparison cohort, with an adjusted hazard ratio (HR) of 1.50 (95% CI 1.29–1.74) estimated in the multivariable Cox model. Age-specific analysis showed that the HR of ICH for COM patients decreased with age, with an adjusted HR of 3.28 (95% CI 1.88–5.75) in the < 40-year age group, which declined to 1.11 (95% CI 0.88–1.40) in the elderly. The incidence of ICH increased with the severity of COM; for those with severe COM the adjusted HR was 4.42 (95% CI 3.31–5.89). For subjects without comorbidities, the incidence of ICH was 1.20-fold (95% CI 1.00–1.45) higher in the COM cohort than in the comparison cohort.

CONCLUSIONS

This study suggests for the first time that COM is an inflammatory factor associated with increased risk of ICH, especially in younger patients.

Open access

Chih-Chang Chang, Praveen V. Mummaneni, Joshua Rivera, Rory Mayer, and Dean Chou

Iatrogenic flat back deformity generally can be treated with a pedicle subtraction osteotomy (PSO) (Chan et al., 2018; Lu and Chou, 2007). One of the difficulties with PSO is that a controlled closure can sometimes be problematic in that there may be translation of the spine, manual pushing of the spine, and significant stress on the pedicle screws, which may risk loosening. The authors present a video of their surgical technique for PSO closed by passive closure using an open-bottom hinged table. This allows the osteotomy to be closed without any force on the screws and without significant manual forces on the spinal column.

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

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Chih-Chang Chang, Joshua Rivera, Brenton Pennicooke, Dean Chou, and Praveen V. Mummaneni

Adult spinal deformity (ASD) is an increasing disease entity as the population ages. An emerging minimally invasive surgery (MIS) option for the treatment of ASD is the oblique lumbar interbody fusion (OLIF), which allows indirect foraminal decompression of stenosis as well as segmental deformity correction (DiGiorgio et al., 2017). The authors utilize computer-assisted navigation with OLIF to reduce radiation exposure and improve time efficiency. The authors present a video of navigated oblique lumbar interbody fusion at L3–5 followed by open posterior screw-rod fixation.

The video can be found here: https://youtu.be/zKDT7PhMYf8.

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Chih-Chuan Yang, Hung-Chang Chen, and Chien-Min Chen

✓Presacral tumors are rarely found in adults. Resections via open abdominal or sacral approaches have been advocated traditionally as the preferred treatment for these tumors. The endoscopic surgical technique provides direct visualization of the presacral or retroperitoneal space. The authors report on a 67-year-old man who experienced difficulty in defecation off and on for 5 weeks, and recently he had suffered indistinct pain in the lower abdomen. The abdominal computed tomography scan revealed a 5.1 × 4.2–cm, homogeneous, low-density, well-defined mass arising from the left sciatic nerve abutting the left piriformis muscle, favoring a diagnosis of benign neurogenic tumor. Endoscopically guided resection was applied, with a favorable outcome. This procedure represents a less invasive approach that may be useful for benign retroperitoneal pelvic tumors.

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Hsuan-Kan Chang, Chih-Chang Chang, Tsung-Hsi Tu, Jau-Ching Wu, Wen-Cheng Huang, Li-Yu Fay, Peng-Yuan Chang, Ching-Lan Wu, and Henrich Cheng

OBJECTIVE

Many reports have successfully demonstrated that cervical disc arthroplasty (CDA) can preserve range of motion after 1- or 2-level discectomy. However, few studies have addressed the extent of changes in segmental mobility after CDA or their clinical correlations.

METHODS

Data from consecutive patients who underwent 1-level CDA were retrospectively reviewed. Indications for surgery were medically intractable degenerative disc disease and spondylosis. Clinical outcomes, including visual analog scale (VAS)–measured neck and arm pain, Neck Disability Index (NDI), and Japanese Orthopaedic Association (JOA) scores, were analyzed. Radiographic outcomes, including C2–7 Cobb angle, the difference between pre- and postoperative C2–7 Cobb angle (ΔC2–7 Cobb angle), sagittal vertical axis (SVA), the difference between pre- and postoperative SVA (ΔSVA), segmental range of motion (ROM), and the difference between pre- and postoperative ROM (ΔROM), were assessed for their association with clinical outcomes. All patients underwent CT scanning, by which the presence and severity of heterotopic ossification (HO) were determined during the follow-up.

RESULTS

A total of 50 patients (mean age 45.6 ± 9.33 years) underwent a 1-level CDA (Prestige LP disc) and were followed up for a mean duration of 27.7 ± 8.76 months. All clinical outcomes, including VAS, NDI, and JOA scores, improved significantly after surgery. Preoperative and postoperative ROM values were similar (mean 9.5° vs 9.0°, p > 0.05) at each indexed level. The mean changes in segmental mobility (ΔROM) were −0.5° ± 6.13°. Patients with increased segmental mobility after surgery (ΔROM > 0°) had a lower incidence of HO and HO that was less severe (p = 0.048) than those whose ΔROM was < 0°. Segmental mobility (ROM) was significantly lower in patients with higher HO grade (p = 0.012), but it did not affect the clinical outcomes. The preoperative and postoperative C2–7 Cobb angles and SVA remained similar. The postoperative C2–7 Cobb angles, SVA, ΔC2–7 Cobb angles, and ΔSVA were not correlated to clinical outcomes after CDA.

CONCLUSIONS

Segmental mobility (as reflected by the mean ROM) and overall cervical alignment (i.e., mean SVA and C2–7 Cobb angle) had no significant impact on clinical outcomes after 1-level CDA. Patients with increased segmental mobility (ΔROM > 0°) had significantly less HO and similarly improved clinical outcomes than those with decreased segmental mobility (ΔROM < 0°).

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Can Zhang, Chih-Chang Chang, Praveen V. Mummaneni, Chenghua Yuan, Sanjay Dhall, Fengzeng Jian, Nalin Gupta, and Dean Chou

OBJECTIVE

Recurrent tethered cord syndrome (TCS), believed to result from tension on the distal portion of the spinal cord, causes a constellation of neurological symptoms. Detethering surgery has been the traditional treatment for TCS. However, in cases of recurrent TCS, there is a risk of new neurological deficits developing, and subsequent retethering is difficult to prevent. Spinal column shortening has been proposed as an alternative technique to reduce the tension on the spinal cord without incurring the morbidity of revision surgery on the spinal cord. The authors compared the perioperative outcomes and morbidity of patients who were treated with one or the other procedure.

METHODS

The medical records of 16 adult patients with recurrent TCS who were treated between 2005 and 2018 were reviewed. Eight patients underwent spinal column shortening, and 8 patients underwent revision detethering surgery. Patient demographics, clinical outcomes, and perioperative factors were analyzed. The authors include a video to illustrate their technique of spinal column shortening.

RESULTS

Within the spinal column shortening group, no patients experienced any complications, and all 8 patients either improved or stabilized with regard to lower-extremity and bowel and bladder function. Within the revision detethering group, 2 patients had worsening of lower-extremity strength, 3 patients had worsening of bowel and bladder function, and 1 patient had improvement in bladder function. Also, 3 patients had wound-related complications. The median estimated blood loss was 731 ml in the shortening group and 163 ml in the revision detethering group. The median operative time was 358 minutes in the shortening group and 226 minutes in the revision detethering group.

CONCLUSIONS

Clinical outcomes were comparable between the groups, but none of the spinal column shortening patients experienced worsening, whereas 3 of the revision detethering patients did and also had wound-related complications. Although the operative times and blood loss were higher in the spinal column shortening group, this procedure may be an alternative to revision detethering in extremely scarred or complex wound revision cases.

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Minghao Wang, Dean Chou, Chih-Chang Chang, Ankit Hirpara, Yilin Liu, Andrew K. Chan, Brenton Pennicooke, and Praveen V. Mummaneni

OBJECTIVE

Both structural allograft and PEEK have been used for anterior cervical discectomy and fusion (ACDF). There are reports that PEEK has a higher pseudarthrosis rate than structural allograft. The authors compared pseudarthrosis, revision, subsidence, and loss of lordosis rates in patients with PEEK and structural allograft.

METHODS

The authors performed a retrospective review of patients who were treated with ACDF at their hospital between 2005 and 2017. Inclusion criteria were adult patients with either PEEK or structural allograft, anterior plate fixation, and a minimum 2-year follow-up. Exclusion criteria were hybrid PEEK and allograft cases, additional posterior surgery, adjacent corpectomies, infection, tumor, stand-alone or integrated screw and cage devices, bone morphogenetic protein use, or lack of a minimum 2-year follow-up. Demographic variables, number of treated levels, interbody type (PEEK cage vs structural allograft), graft packing material, pseudarthrosis rates, revision surgery rates, subsidence, and cervical lordosis changes were collected. These data were analyzed by Pearson’s chi-square test (or Fisher’s exact test, according to the sample size and expected value) and Student t-test.

RESULTS

A total of 168 patients (264 levels total, mean follow-up time 39.5 ± 24.0 months) were analyzed. Sixty-one patients had PEEK, and 107 patients had structural allograft. Pseudarthrosis rates for 1-level fusions were 5.4% (PEEK) and 3.4% (allograft) (p > 0.05); 2-level fusions were 7.1% (PEEK) and 8.1% (allograft) (p > 0.05); and ≥ 3-level fusions were 10% (PEEK) and 11.1% (allograft) (p > 0.05). There was no statistical difference in the subsidence magnitude between PEEK and allograft in 1-, 2-, and ≥ 3-level ACDF (p > 0.05). Postoperative lordosis loss was not different between cohorts for 1- and 2-level surgeries.

CONCLUSIONS

In 1- and 2-level ACDF with plating involving the same number of fusion levels, there was no statistically significant difference in the pseudarthrosis rate, revision surgery rate, subsidence, and lordosis loss between PEEK cages and structural allograft.

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Minghao Wang, Praveen V. Mummaneni, Zhuo Xi, Chih-Chang Chang, Joshua Rivera, Jeremy Guinn, Rory Mayer, and Dean Chou

OBJECTIVE

A consequence of anterior cervical discectomy and fusion (ACDF) is graft subsidence, potentially leading to kyphosis, nonunion, foraminal stenosis, and recurrent pain. Bone density, as measured in Hounsfield units (HUs) on CT, may be associated with subsidence. The authors evaluated the association between HUs and subsidence rates after ACDF.

METHODS

A retrospective study of patients treated with single-level ACDF at the University of California, San Francisco, from 2008 to 2017 was performed. HU values were measured according to previously published methods. Only patients with preoperative CT, minimum 1-year follow-up, and single-level ACDF were included. Patients with posterior surgery, tumor, infection, trauma, deformity, or osteoporosis treatment were excluded. Changes in segmental height were measured at 1-year follow-up compared with immediate postoperative radiographs. Subsidence was defined as segmental height loss of more than 2 mm.

RESULTS

A total of 91 patients met inclusion criteria. There was no significant difference in age or sex between the subsidence and nonsubsidence groups. Mean HU values in the subsidence group (320.8 ± 23.9, n = 8) were significantly lower than those of the nonsubsidence group (389.1 ± 53.7, n = 83, p < 0.01, t-test). There was a negative correlation between the HU values and segmental height loss (Pearson’s coefficient −0.735, p = 0.01). Using receiver operating characteristic curves, the area under the curve was 0.89, and the most appropriate threshold of HU value was 343.7 (sensitivity 77.1%, specificity 87.5%). A preoperative lower HU is a risk factor for postoperative subsidence (binary logistic regression, p < 0.05). The subsidence rate and distance between allograft and polyetheretherketone (PEEK) materials were not significantly different (PEEK 0.9 ± 0.7 mm, allograft 1.0 ± 0.7 mm; p > 0.05).

CONCLUSIONS

Lower preoperative CT HU values are associated with cage subsidence in single-level ACDF. Preoperative measurement of HUs may be useful in predicting outcomes after ACDF.

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Zhuo Xi, Dean Chou, Praveen V. Mummaneni, Huibing Ruan, Charles Eichler, Chih-Chang Chang, and Shane Burch

OBJECTIVE

In adult spinal deformity and degenerative conditions of the spine, interbody fusion to the sacrum often is performed to enhance arthrodesis, induce lordosis, and alleviate stenosis. Anterior lumbar interbody fusion (ALIF) has traditionally been performed, but minimally invasive oblique lumbar interbody fusion (OLIF) may or may not cause less morbidity because less retraction of the abdominal viscera is required. The authors evaluated whether there was a difference between the results of ALIF and OLIF in multilevel anterior or lateral interbody fusion to the sacrum.

METHODS

Patients from 2013 to 2018 who underwent multilevel ALIF or OLIF to the sacrum were retrospectively studied. Inclusion criteria were adult spinal deformity or degenerative pathology and multilevel ALIF or OLIF to the sacrum. Demographic, implant, perioperative, and radiographic variables were collected. Statistical calculations were performed for significant differences.

RESULTS

Data from a total of 127 patients were analyzed (66 OLIF patients and 61 ALIF patients). The mean follow-up times were 27.21 (ALIF) and 24.11 (OLIF) months. The mean surgical time was 251.48 minutes for ALIF patients and 234.48 minutes for OLIF patients (p = 0.154). The mean hospital stay was 7.79 days for ALIF patients and 7.02 days for OLIF patients (p = 0.159). The mean time to being able to eat solid food was 4.03 days for ALIF patients and 1.30 days for OLIF patients (p < 0.001). After excluding patients who had undergone L5–S1 posterior column osteotomy, 54 ALIF patients and 41 OLIF patients were analyzed for L5–S1 radiographic changes. The mean cage height was 14.94 mm for ALIF patients and 13.56 mm for OLIF patients (p = 0.001), and the mean cage lordosis was 15.87° in the ALIF group and 16.81° in the OLIF group (p = 0.278). The mean increases in anterior disc height were 7.34 mm and 4.72 mm for the ALIF and OLIF groups, respectively (p = 0.001), and the mean increases in posterior disc height were 3.35 mm and 1.24 mm (p < 0.001), respectively. The mean change in L5–S1 lordosis was 4.33° for ALIF patients and 4.59° for OLIF patients (p = 0.829).

CONCLUSIONS

Patients who underwent multilevel OLIF and ALIF to the sacrum had comparable operative times. OLIF was associated with a quicker ileus recovery and less blood loss. At L5–S1, ALIF allowed larger cages to be placed, resulting in a greater disc height change, but there was no significant difference in L5–S1 segmental lordosis.