Search Results

You are looking at 1 - 5 of 5 items for

  • Author or Editor: Won Hyung A. Ryu x
Clear All Modify Search
Restricted access

Adrianna Ranger, Gregory Bowden and Won Hyung A. Ryu

In most instances, initial surgery to untether a tethered spinal cord is successful. But what happens when it is not? The authors describe the case of a now 18-year-old woman with spina bifida in whom surgery for tethered cord was required on two occasions. In both instances, due to the extent of her underlying lesion and fibrous tissue, only partial detethering was possible without acutely sacrificing significant neurological function. The authors detail the patient's course and review the peer-reviewed scientific literature on outcomes in patients in whom only partial cord detethering is achieved.

In their review of all case series and clinical studies pertaining to the surgical treatment of tethered cord syndrome identified during an online search of 2184 scientific abstracts and 2 major neurosurgery textbooks, excluding the present case, the authors identified 53 confirmed or presumed cases of incomplete detethering in eight articles, incorporating 390 patients, for an overall prevalence of roughly 13.6%. Although no investigators have reported statistical comparisons of outcomes in those in whom just partial and complete detethering has been achieved, the evidence generally suggests poorer outcomes in the former. Prospective multicenter studies addressing this important issue clearly are warranted. To date, the authors believe that incomplete detethering is grossly underreported in the medical literature.

Free access

Won Hyung A. Ryu, Michael M. H. Yang, Sandeep Muram, W. Bradley Jacobs, Steven Casha and Jay Riva-Cambrin

OBJECTIVE

As the cost of health care continues to increase, there is a growing emphasis on evaluating the relative economic value of treatment options to guide resource allocation. The objective of this systematic review was to evaluate the current evidence regarding the cost-effectiveness of cranial neurosurgery procedures.

METHODS

The authors performed a systematic review of the literature using PubMed, EMBASE, and the Cochrane Library, focusing on themes of economic evaluation and cranial neurosurgery following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Included studies were publications of cost-effectiveness analysis or cost-utility analysis between 1995 and 2017 in which health utility outcomes in life years (LYs), quality-adjusted life years (QALYs), or disability-adjusted life years (DALYs) were used. Three independent reviewers conducted the study appraisal, data abstraction, and quality assessment, with differences resolved by consensus discussion.

RESULTS

In total, 3485 citations were reviewed, with 53 studies meeting the inclusion criteria. Of those, 34 studies were published in the last 5 years. The most common subspecialty focus was cerebrovascular (32%), followed by neurooncology (26%) and functional neurosurgery (24%). Twenty-eight (53%) studies, using a willingness to pay threshold of US$50,000 per QALY or LY, found a specific surgical treatment to be cost-effective. In addition, there were 11 (21%) studies that found a specific surgical option to be economically dominant (both cost saving and having superior outcome), including endovascular thrombectomy for acute ischemic stroke, epilepsy surgery for drug-refractory epilepsy, and endoscopic pituitary tumor resection.

CONCLUSIONS

There is an increasing number of cost-effectiveness studies in cranial neurosurgery, especially within the last 5 years. Although there are numerous procedures, such as endovascular thrombectomy for acute ischemic stroke, that have been conclusively proven to be cost-effective, there remain promising interventions in current practice that have yet to meet cost-effectiveness thresholds.

Restricted access

Heterotopic ossification and radiographic adjacent-segment disease after cervical disc arthroplasty

Presented at the 2019 AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves

Michael M. H. Yang, Won Hyung A. Ryu, Steven Casha, Stephan DuPlessis, W. Bradley Jacobs and R. John Hurlbert

OBJECTIVE

Cervical disc arthroplasty (CDA) is an accepted motion-sparing technique associated with favorable patient outcomes. However, heterotopic ossification (HO) and adjacent-segment degeneration are poorly understood adverse events that can be observed after CDA. The purpose of this study was to retrospectively examine 1) the effect of the residual exposed endplate (REE) on HO, and 2) identify risk factors predicting radiographic adjacent-segment disease (rASD) in a consecutive cohort of CDA patients.

METHODS

A retrospective cohort study was performed on consecutive adult patients (≥ 18 years) who underwent 1- or 2-level CDA at the University of Calgary between 2002 and 2015 with > 1-year follow-up. REE was calculated by subtracting the anteroposterior (AP) diameter of the arthroplasty device from the native AP endplate diameter measured on lateral radiographs. HO was graded using the McAfee classification (low grade, 0–2; high grade, 3 and 4). Change in AP endplate diameter over time was measured at the index and adjacent levels to indicate progressive rASD.

RESULTS

Forty-five patients (58 levels) underwent CDA during the study period. The mean age was 46 years (SD 10 years). Twenty-six patients (58%) were male. The median follow-up was 29 months (IQR 42 months). Thirty-three patients (73%) underwent 1-level CDA. High-grade HO developed at 19 levels (33%). The mean REE was 2.4 mm in the high-grade HO group and 1.6 mm in the low-grade HO group (p = 0.02). On multivariable analysis, patients with REE > 2 mm had a 4.5-times-higher odds of developing high-grade HO (p = 0.02) than patients with REE ≤ 2 mm. No significant relationship was observed between the type of artificial disc and the development of high-grade HO (p = 0.1). RASD was more likely to develop in the lower cervical spine (p = 0.001) and increased with time (p < 0.001). The presence of an artificial disc was highly protective against degenerative changes at the index level of operation (p < 0.001) but did not influence degeneration in the adjacent segments.

CONCLUSIONS

In patients undergoing CDA, high-grade HO was predicted by REE. Therefore, maximizing the implant-endplate interface may help to reduce high-grade HO and preserve motion. RASD increases in an obligatory manner following CDA and is highly linked to specific levels (e.g., C6–7) rather than the presence or absence of an adjacent arthroplasty device. The presence of an artificial disc is, however, protective against further degenerative change at the index level of operation.

Restricted access

Philippe A. Chouinard, Christopher L. Striemer, Won Hyung A. Ryu, Irene Sperandio, Melvyn A. Goodale, David A. Nicolle, Brian Rotenberg and Neil Duggal

Compression induced by a pituitary tumor on the optic chiasm can generate visual field deficits, yet it is unknown how this compression affects the retinotopic organization of the visual cortex. It is also not known how the effect of the tumor on the retinotopic organization of the visual cortex changes after decompression. The authors used functional MRI (fMRI) to map the retinotopic organization of the visual cortex in a 68-year-old right-handed woman before and 3 months after surgery for a recurrent pituitary macroadenoma. The authors demonstrated that longitudinal changes in visual field perimetry, as assessed by the automated Humphrey visual field test, correlated with longitudinal changes in fMRI activation in a retinotopic manner. In other words, after decompression of the optic chiasm, fMRI charted the recruitment of the visual cortex in a way that matched gains in visual field perimetry. On the basis of this case, the authors propose that fMRI can chart neural plasticity of the visual cortex on an individual basis and that it can also serve as a complementary tool in decision making with respect to management of patients with chiasmal compression.