Magnetic Resonance Imaging of the Codman Microsensor Transducer Used for Intraspinal Pressure Monitoring: Findings From the Injured Spinal Cord Pressure Evaluation Study

Fabrication and characterization of polymer optical waveguide Bragg grating for pulse signal sensing

Polymer materials have the advantages of a low Young's modulus and low-cost preparation process. In this paper, a polymer-based optical waveguide pressure sensor based on a Bragg structure is proposed. The change in the Bragg wavelength in the output spectrum of the waveguide Bragg grating (WBG) is used to linearly characterize the change in pressure acting on the device. The polymer-based WBG was developed through a polymer film preparation process, and the experimental results show that the output signal of the device has a sensitivity of 1.275 nm/kPa with a measurement range of 0-12 kPa and an accuracy of 1 kPa. The experimental results indicate that the device already perfectly responds to a pulse signal. It has significant potential application value in medical diagnostics and health testing, such as blood pressure monitoring, sleep quality monitoring, and tactile sensing.

Elevated intraspinal pressure drives edema progression after acute compression spinal cord injury in rabbits

Elevated intraspinal pressure (ISP) following traumatic spinal cord injury (tSCI) can be an important factor for secondary SCI that may result in greater tissue damage and functional deficits. Our present study aimed to investigate the dynamic changes in ISP after different degrees of acute compression SCI in rabbits with closed canals and explore its influence on spinal cord pathophysiology. Closed balloon compression injuries were induced with different inflated volumes (40 μl, 50 μl or no inflation) at the T7/8 level in rabbits. ISP was monitored by a SOPHYSA probe at the epicenter within 7 days post-SCI. Edema progression, spinal cord perfusion and damage severity were evaluated by serial multisequence MRI scans, somatosensory evoked potentials (SEPs) and behavioral scores. Histological and blood spinal cord barrier (BSCB) permeability results were subsequently analyzed. The results showed that the ISP waveforms comprised three peaks, significantly increased after tSCI, peaked at 72 h (21.86 ± 3.13 mmHg) in the moderate group or 48 h (31.71 ± 6.02 mmHg) in the severe group and exhibited "slow elevated and fast decreased" or "fast elevated and slow decreased" dynamic changes in both injured groups. Elevated ISP after injury was correlated with spinal cord perfusion and edema progression, leading to secondary lesion enlargement. The secondary damage aggravation can be visualized by diffusion tensor tractography (DTT). Moreover, the BSCB permeability was significantly increased at the epicenter and rostrocaudal segments at 72 h after SCI; by 14 days, notable permeability was still observed at the caudal segment in the severely injured rabbits. Our results suggest that the ISP of rabbits with closed canals increased after acute compression SCI and exhibited different dynamic change patterns in moderately and severely injured rabbits. Elevated ISP exacerbated spinal cord perfusion, drove edema progression and led to secondary lesion enlargement that was strongly associated with BSCB disruption. For severe tSCI, early intervention targeting elevated ISP may be an indispensable choice to rescue spinal cord function.

Trends in Demographics and Markers of Injury Severity in Traumatic Cervical Spinal Cord Injury

Over the past four decades, there have been progressive changes in the epidemiology of traumatic spinal cord injury (tSCI). We assessed trends in demographic and injury-related variables in traumatic cervical spinal cord injury (tCSCI) patients over an 18-year period at a single Level I trauma center. We included all magnetic resonance imaging-confirmed tCSCI patients ≥15 years of age for years 2001-2018. Among 1420 patients, 78.3% were male with a mean age 51.5 years. Etiology included falls (46.9%), motor vehicle collisions (MVCs; 34.2%), and sports injuries (10.9%). Median American Spinal Injury Association (ASIA) Motor Score (AMS) was 44, complete tCSCI was noted in 29.6% of patients, fracture dislocations were noted in 44.7%, and median intramedullary lesion length (IMLL) was 30.8 mm (complete injuries 56.3 mm and incomplete injuries 27.4 mm). Over the study period, mean age and proportion of falls increased (p < 0.001) whereas proportion attributable to MVCs and sports injuries decreased (p < 0.001). Incomplete injuries, AMS, and the proportion of patients with no fracture dislocations increased whereas complete injuries decreased significantly. IMLL declined (p = 0.17) and proportion with hematomyelia did not change significantly. In adjusted regression models, increase in age and decreases in prevalence of MVC mechanism and complete injuries over time remained statistically significant. Changes in demographic and injury-related characteristics of tCSCI patients over time may help explain the observed improvement in outcomes. Further, improved clinical outcomes and drop in IMLL may reflect improvements in initial risk assessment and pre-hospital management, advances in healthcare delivery, and preventive measures including public education.

Efficacy of Ultra-Early (< 12 h), Early (12-24 h), and Late (>24-138.5 h) Surgery with Magnetic Resonance Imaging-Confirmed Decompression in American Spinal Injury Association Impairment Scale Grades A, B, and C Cervical Spinal Cord Injury

In cervical traumatic spinal cord injury (TSCI), the therapeutic effect of timing of surgery on neurological recovery remains uncertain. Additionally, the relationship between extent of decompression, imaging biomarker evidence of injury severity, and outcome is incompletely understood. We investigated the effect of timing of decompression on long-term neurological outcome in patients with complete spinal cord decompression confirmed on postoperative magnetic resonance imaging (MRI). American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade conversion was determined in 72 AIS grades A, B, and C patients 6 months after confirmed decompression. Thirty-two patients underwent decompressive surgery ultra-early (< 12 h), 25 underwent decompressive surgery early (12-24 h), and 15 underwent decompressive surgery late (> 24-138.5 h) after injury. Age, gender, injury mechanism, intramedullary lesion length (IMLL) on MRI, admission ASIA motor score, and surgical technique were not statistically different among groups. Motor complete patients (p = 0.009) and those with fracture dislocations (p = 0.01) tended to be operated on earlier. Improvement of one grade or more was present in 55.6% of AIS grade A, 60.9% of AIS grade B, and 86.4% of AIS grade C patients. Admission AIS motor score (p = 0.0004) and pre-operative IMLL (p = 0.00001) were the strongest predictors of neurological outcome. AIS grade improvement occurred in 65.6%, 60%, and 80% of patients who underwent decompression ultra-early, early, and late, respectively (p = 0.424). Multiple regression analysis revealed that IMLL was the only significant variable predictive of AIS grade conversion to a better grade (odds ratio, 0.908; confidence interval [CI], 0.862-0.957; p < 0.001). We conclude that in patients with post-operative MRI confirmation of complete decompression following cervical TSCI, pre-operative IMLL, not the timing of surgery, determines long-term neurological outcome.

Practical Application of Recent Advances in Diagnostic, Prognostic, and Therapeutic Modalities for Spinal Cord Injury

OBJECTIVE

Spinal cord injury remains a highly morbid entity, with limited treatment modalities in both acute and chronic settings. Clinical research efforts to improve therapeutic guidelines are confounded by initial evaluation inaccuracies, as presentations are frequently complicated by trauma and objective diagnostic and prognostic methods are poorly defined. The purpose of our study was to review recent practical advances for further delineation of these injuries and how such classification may benefit the development of novel treatments.

METHODS

A review was carried out of recent studies reported within the last 5 years for prognostic and diagnostic modalities of acute spinal cord injury.

RESULTS

Substantial efforts have been made to improve the timeliness and accuracy of the initial assessment, not only for the purpose of enhancing prognostication but also in determining the efficacy of new treatments. Whether it be applying traumatic brain injury principles to limit injury extent, external stimulators used for chronic pain conditions to enhance the effects of physical therapy, or creative algorithms incorporating various nerve or muscle transfer techniques, innovative and practical solutions continue to be developed in lieu of definitive treatment. Further development will benefit from enhanced stratification of injury from accurate and practical assessment modalities.

CONCLUSIONS

Recent advances in accurate, timely, and practical classification methods of acute spinal cord injury will assist in the development of novel treatment approaches for both acute and chronic injury alike.

Bioresorbable optical sensor systems for monitoring of intracranial pressure and temperature

Continuous measurements of pressure and temperature within the intracranial, intraocular, and intravascular spaces provide essential diagnostic information for the treatment of traumatic brain injury, glaucoma, and cardiovascular diseases, respectively. Optical sensors are attractive because of their inherent compatibility with magnetic resonance imaging (MRI). Existing implantable optical components use permanent, nonresorbable materials that must be surgically extracted after use. Bioresorbable alternatives, introduced here, bypass this requirement, thereby eliminating the costs and risks of surgeries. Here, millimeter-scale bioresorbable Fabry-Perot interferometers and two dimensional photonic crystal structures enable precise, continuous measurements of pressure and temperature. Combined mechanical and optical simulations reveal the fundamental sensing mechanisms. In vitro studies and histopathological evaluations quantify the measurement accuracies, operational lifetimes, and biocompatibility of these systems. In vivo demonstrations establish clinically relevant performance attributes. The materials, device designs, and fabrication approaches outlined here establish broad foundational capabilities for diverse classes of bioresorbable optical sensors.

Intraspinal Pressure Monitoring and Extensive Duroplasty in the Acute Phase of Traumatic Spinal Cord Injury: A Systematic Review

OBJECTIVE

The prognosis in cervical spinal cord injury is poor, and surgical and neurointensive care management need further improvement. Monitoring of the intraspinal pressure (ISP) at an early stage after traumatic spinal cord injury (tSCI) is useful clinically.

MATERIALS AND METHODS

Obtaining continuous spinal cord perfusion pressure (SCPP) measurements based on the difference between mean arterial pressure and ISP allows offering best medical and surgical treatment during this critical phase of tSCI. A search was carried out with PubMed, Embase, and Google Scholar up to January 10, 2017. Articles resulting from these searches and relevant references cited in those articles were reviewed.

RESULTS

The optimal SCPP was found to be between 90 and 100 mm Hg and mean arterial pressure of 110-130. Laminectomy alone was found to be ineffective in the reduction of ISP because it does not lower the pressure exerted by dura on the swollen spinal cord. Therefore, bony decompression with durotomy or duroplasty seems to be the procedure of choice to reduce the ISP less than 20 mm Hg.

CONCLUSIONS

A randomized controlled trial is required to determine whether laminectomy with durotomy and monitoring of ISP with SCPP optimization improve neurological recovery after tSCI.