Preoperative Mobile Health Data Improve Predictions of Recovery From Lumbar Spine Surgery.

BACKGROUND AND OBJECTIVES: Neurosurgeons and hospitals devote tremendous resources to improving recovery from lumbar spine surgery. Current efforts to predict surgical recovery rely on one-time patient report and health record information. However, longitudinal mobile health (mHealth) assessments integrating symptom dynamics from ecological momentary assessment (EMA) and wearable biometric data may capture important influences on recovery. Our objective was to evaluate whether a preoperative mHealth assessment integrating EMA with Fitbit monitoring improved predictions of spine surgery recovery. METHODS: Patients age 21-85 years undergoing lumbar surgery for degenerative disease between 2021 and 2023 were recruited. For up to 3 weeks preoperatively, participants completed EMAs up to 5 times daily asking about momentary pain, disability, depression, and catastrophizing. At the same time, they were passively monitored using Fitbit trackers. Study outcomes were good/excellent recovery on the Quality of Recovery-15 (QOR-15) and a clinically important change in Patient-Reported Outcomes Measurement Information System Pain Interference 1 month postoperatively. After feature engineering, several machine learning prediction models were tested. Prediction performance was measured using the c-statistic. RESULTS: A total of 133 participants were included, with a median (IQR) age of 62 (53, 68) years, and 56% were female. The median (IQR) number of preoperative EMAs completed was 78 (61, 95), and the median (IQR) number of days with usable Fitbit data was 17 (12, 21). 63 patients (48%) achieved a clinically meaningful improvement in Patient-Reported Outcomes Measurement Information System pain interference. Compared with traditional evaluations alone, mHealth evaluations led to a 34% improvement in predictions for pain interference (c = 0.82 vs c = 0.61). 49 patients (40%) had a good or excellent recovery based on the QOR-15. Including preoperative mHealth data led to a 30% improvement in predictions of QOR-15 (c = 0.70 vs c = 0.54). CONCLUSION: Multimodal mHealth evaluations improve predictions of lumbar surgery outcomes. These methods may be useful for informing patient selection and perioperative recovery strategies.

Implications of Preoperative Depression for Lumbar Spine Surgery Outcomes: A Systematic Review and Meta-Analysis.

Importance: Comorbid depression is common among patients with degenerative lumbar spine disease. Although a well-researched topic, the evidence of the role of depression in spine surgery outcomes remains inconclusive. Objective: To investigate the association between preoperative depression and patient-reported outcome measures (PROMs) after lumbar spine surgery. Data Sources: A systematic search of PubMed, Cochrane Database of Systematic Reviews, Embase, Scopus, PsychInfo, Web of Science, and ClinicalTrials.gov was performed from database inception to September 14, 2023. Study Selection: Included studies involved adults undergoing lumbar spine surgery and compared PROMs in patients with vs those without depression. Studies evaluating the correlation between preoperative depression and disease severity were also included. Data Extraction and Synthesis: All data were independently extracted by 2 authors and independently verified by a third author. Study quality was assessed using Newcastle-Ottawa Scale. Random-effects meta-analysis was used to synthesize data, and I2 was used to assess heterogeneity. Metaregression was performed to identify factors explaining the heterogeneity. Main Outcomes and Measures: The primary outcome was the standardized mean difference (SMD) of change from preoperative baseline to postoperative follow-up in PROMs of disability, pain, and physical function for patients with vs without depression. Secondary outcomes were preoperative and postoperative differences in absolute disease severity for these 2 patient populations. Results: Of the 8459 articles identified, 44 were included in the analysis. These studies involved 21 452 patients with a mean (SD) age of 57 (8) years and included 11 747 females (55%). Among these studies, the median (range) follow-up duration was 12 (6-120) months. The pooled estimates of disability, pain, and physical function showed that patients with depression experienced a greater magnitude of improvement compared with patients without depression, but this difference was not significant (SMD, 0.04 [95% CI, -0.02 to 0.10]; I2 = 75%; P = .21). Nonetheless, patients with depression presented with worse preoperative disease severity in disability, pain, and physical function (SMD, -0.52 [95% CI, -0.62 to -0.41]; I2 = 89%; P < .001), which remained worse postoperatively (SMD, -0.52 [95% CI, -0.75 to -0.28]; I2 = 98%; P < .001). There was no significant correlation between depression severity and the primary outcome. A multivariable metaregression analysis suggested that age, sex (male to female ratio), percentage of comorbidities, and follow-up attrition were significant sources of variance. Conclusions and Relevance: Results of this systematic review and meta-analysis suggested that, although patients with depression had worse disease severity both before and after surgery compared with patients without depression, they had significant potential for recovery in disability, pain, and physical function. Further investigations are needed to examine the association between spine-related disability and depression as well as the role of perioperative mental health treatments.

Assessing the impact of obesity on full endoscopic spine surgery: surgical site infections, surgery durations, early complications, and short-term functional outcomes.

OBJECTIVE: An increasing number of obese patients undergoing elective spine surgery has been reported. Obesity has been associated with a substantially higher number of surgical site infections and a longer surgery duration. However, there is a lack of research investigating the intersection of obesity and full endoscopic spine surgery (FESS) in terms of functional outcomes and complications. The aim of this study was to evaluate wound site infections and functional outcomes following FESS in obese patients. METHODS: Patients undergoing lumbar FESS at the participating institutions from March 2020 to March 2023 for degenerative pathologies were included in the analysis. Patients were divided into obese (BMI > 30 kg/m2) and nonobese (BMI 18-30 kg/m2) groups. Data were collected prospectively using an approved smartphone application for 3 months postsurgery. Parameters included demographics, surgical details, a virtual wound checkup, the visual analog scale for back and leg pain, and the Oswestry Disability Index (ODI) as a functional outcome measure. RESULTS: A total of 118 patients were included in the analysis, with 53 patients in the obese group and 65 in the nonobese group. Group homogeneity was satisfactory regarding patient age (obese vs nonobese: 55.5 ± 14.7 years vs 59.1 ± 17.1 years, p = 0.25) and sex (p = 0.85). No surgical site infection requiring operative revision was reported for either group. No significant differences for blood loss per level (obese vs nonobese: 9.7 ± 16.8 ml vs 8.0 ± 13.3 ml, p = 0.49) or duration of surgery per level (obese vs nonobese: 91.2 ± 57.7 minutes vs 76.8 ± 39.2 minutes, p = 0.44) were reported between groups. Obese patients showed significantly faster improvement regarding ODI (-3.0 ± 9.8 vs 0.7 ± 11.3, p = 0.01) and leg pain (-4.4 ± 3.2 vs -2.9 ± 3.7, p = 0.03) 7 days postsurgery. This effect was no longer significant 90 days postsurgery for either ODI (obese vs nonobese: -11.4 ± 11.4 vs -9.1 ± 9.6, p = 0.24) or leg pain (obese vs nonobese: -4.3 ± 3.9 vs -3.5 ± 3.8, p = 0.28). CONCLUSIONS: The results highlight the effectiveness and safety of lumbar FESS in obese patients. Unlike with open spine surgery, obese patients did not experience significant increases in surgery time or postoperative complications. Interestingly, obese patients demonstrated faster early recovery, as indicated by significantly greater improvements in ODI and leg pain at 7 days after surgery. However, there was no difference in improvement between the groups at 90 days after surgery.

Impact of Upper Limb Motor Recovery on Functional Independence after Traumatic Low Cervical Spinal Cord Injury.

Cervical Spinal Cord Injury (SCI) causes devastating loss of upper limb function and independence. Restoration of upper limb function can have a profound impact on independence and quality-of-life. In low-cervical SCI (level C5-C8), upper limb function can be restored via reinnervation strategies such as nerve transfer surgery. However, the translation of recovered upper limb motor function into functional independence in activities of daily living (ADLs) remains unknown in low cervical SCI (i.e., tetraplegia). The objective of this study was to evaluate the association of patterns in upper limb motor recovery with functional independence in ADLs. This will then inform prioritization of reinnervation strategies focused to maximize function in patients with tetraplegia. This retrospective study performed a secondary analysis of low cervical SCI patients (C5-C8) enrolled in the SCI Model Systems (SCIMS) database. Baseline neurological examinations and their association with functional independence in major ADLs, i.e., eating, bladder management, and transfers (bed/wheelchair/chair) were evaluated. Motor functional recovery was defined as achieving motor strength, in modified research council (MRC) grade, of 3/5 at one-year from 2/5 at baseline. The association of motor function recovery with functional independence at one year follow-up was compared in patients with recovered elbow flexion (C5), wrist extension (C6), elbow extension (C7), and finger flexion (C8). A multivariable logistic regression analysis, adjusting for known factors influencing recovery following SCI, was performed to evaluate the impact of motor function at one year on a composite outcome of functional independence in major ADLs. Composite outcome was defined as functional independence measure score of 6 or higher (complete independence) in at least 2 domains among eating, bladder management, and transfers. Between 1992 and 2016, 1,090 patients with low cervical SCI and complete neurological/ functional measures were included. At baseline, 67% of patients had complete SCI and 33% had incomplete SCI. The majority of patients were dependent in eating, bladder management, and transfers. At one-year follow-up, the largest proportion of patients who recovered motor function in finger flexion (C8) and elbow extension (C7) gained independence in eating, bladder management, and transfers. In multivariable analysis, patients who had recovered finger flexion (C8) or elbow extension (C7) had higher odds of gaining independence in a composite of major ADLs (odds ratio [OR]=3.13 and OR=2.87, respectively, p<0.001). Age 60 years (OR=0.44, p=0.01), and complete SCI (OR=0.43, p=0.002) were associated with reduced odds of gaining independence in ADLs. After cervical SCI, finger flexion (C8) and elbow extension (C7) recovery translate into greater independence in eating, bladder management and transfers. These results can be used to design individualized reinnervation plans to reanimate upper limb function and maximize independence in patients with low cervical SCI.

Feasibility of postoperative diffusion-weighted imaging to assess representations of spinal cord microstructure in cervical spondylotic myelopathy.

OBJECTIVE: Diffusion basis spectrum imaging (DBSI) has shown promise in evaluating cervical spinal cord structural changes in patients with cervical spondylotic myelopathy (CSM). DBSI may also be valuable in the postoperative setting by serially tracking spinal cord microstructural changes following decompressive cervical spine surgery. Currently, there is a paucity of studies investigating this topic, likely because of challenges in resolving signal distortions from spinal instrumentation. Therefore, the objective of this study was to assess the feasibility of DBSI metrics extracted from the C3 spinal level to evaluate CSM patients postoperatively. METHODS: Fifty CSM patients and 20 healthy controls were enrolled in a single-center prospective study between 2018 and 2020. All patients and healthy controls underwent preoperative and postoperative diffusion-weighted MRI (dMRI) at a 2-year follow-up. All CSM patients underwent decompressive cervical surgery. The modified Japanese Orthopaedic Association (mJOA) score was used to categorize CSM patients as having mild, moderate, or severe myelopathy. DBSI metrics were extracted from the C3 spinal cord level to minimize image artifact and reduce partial volume effects. DBSI anisotropic tensors evaluated white matter tracts through fractional anisotropy, axial diffusivity, radial diffusivity, and fiber fraction. DBSI isotropic tensors assessed extra-axonal pathology through restricted and nonrestricted fractions. RESULTS: Of the 50 CSM patients, both baseline and postoperative dMR images with sufficient quality for analysis were obtained in 27 patients. These included 15 patients with mild CSM (mJOA scores 15-17), 7 with moderate CSM (scores 12-14), and 5 with severe CSM (scores 0-11), who were followed up for a mean of 23.5 (SD 4.1, range 11-31) months. All preoperative C3-level DBSI measures were significantly different between CSM patients and healthy controls (p < 0.05), except DBSI fractional anisotropy (p = 0.31). At the 2-year follow-up, the same significance pattern was found between CSM patients and healthy controls, except DBSI radial diffusivity was no longer statistically significant (p = 0.75). When assessing change (i.e., postoperative - preoperative values) in C3-level DBSI measures, CSM patients exhibited significant decreases in DBSI radial diffusivity (p = 0.02), suggesting improvement in myelin integrity (i.e., remyelination) at the 2-year follow-up. Among healthy controls, there was no significant difference in DBSI metrics over time. CONCLUSIONS: DBSI metrics derived from dMRI at the C3 spinal level can be used to provide meaningful insights into representations of the spinal cord microstructure of CSM patients at baseline and 2-year follow-up. DBSI may have the potential to characterize white matter tract recovery and inform outcomes following decompressive cervical surgery for CSM.

Mechanomyography as a Surgical Adjunct for Treatment of Chronic Entrapment Neuropathy: A Case Series.

BACKGROUND: Chronic entrapment neuropathy results in a clinical syndrome ranging from mild pain to debilitating atrophy. There remains a lack of objective metrics that quantify nerve dysfunction and guide surgical decision-making. Mechanomyography (MMG) reflects mechanical motor activity after stimulation of neuromuscular tissue and may indicate underlying nerve dysfunction. OBJECTIVE: To evaluate the role of MMG as a surgical adjunct in treating chronic entrapment neuropathies. METHODS: Patients 18 years or older with cubital tunnel syndrome (n = 8) and common peroneal neuropathy (n = 15) were enrolled. Surgical decompression of entrapped nerves was performed with intraoperative MMG of the hypothenar and tibialis anterior muscles. MMG stimulus thresholds (MMG-st) were correlated with compound muscle action potential (CMAP), motor nerve conduction velocity, baseline functional status, and clinical outcomes. RESULTS: After nerve decompression, MMG-st significantly reduced, the mean reduction of 0.5 mA (95% CI: 0.3-0.7, P < .001). On bivariate analysis, MMG-st exhibited significant negative correlation with common peroneal nerve CMAP ( P < .05), but no association with ulnar nerve CMAP and motor nerve conduction velocity. On preoperative electrodiagnosis, 60% of nerves had axonal loss and 40% had conduction block. The MMG-st was higher in the nerves with axonal loss as compared with the nerves with conduction block. MMG-st was negatively correlated with preoperative hand strength (grip/pinch) and foot-dorsiflexion/toe-extension strength ( P < .05). At the final visit, MMG-st significantly correlated with pain, PROMIS-10 physical function, and Oswestry Disability Index ( P < .05). CONCLUSION: MMG-st may serve as a surgical adjunct indicating axonal integrity in chronic entrapment neuropathies which may aid in clinical decision-making and prognostication of functional outcomes.

Predictors of Postoperative Segmental and Overall Lumbar Lordosis in Minimally Invasive Transforaminal Lumbar Interbody Fusion: A Consecutive Case Series.

STUDY DESIGN: Retrospective Case-Series. OBJECTIVES: Due to heterogeneity in previous studies, the effect of MI-TLIF on postoperative segmental lordosis (SL) and lumbar lordosis (LL) remains unclear. Therefore, we aim to identify radiographic factors associated with lordosis after surgery in a homogenous series of MI-TLIF patients. METHODS: A single-center retrospective review identified consecutive patients who underwent single-level MI-TLIF for grade 1 degenerative spondylolisthesis from 2015-2020. All surgeries underwent unilateral facetectomies and a contralateral facet release with expandable interbody cages. PROs included the ODI and NRS-BP for low-back pain. Radiographic measures included SL, disc height, percent spondylolisthesis, cage positioning, LL, PI-LL mismatch, sacral-slope, and pelvic-tilt. Surgeries were considered "lordosing" if the change in postoperative SL was ≥ +4° and "kyphosing" if ≤ -4°. Predictors of change in SL/LL were evaluated using Pearson's correlation and multivariable regression. RESULTS: A total of 73 patients with an average follow-up of 22.5 (range 12-61) months were included. Patients experienced significant improvements in ODI (29% ± 22% improvement, P < .001) and NRS-BP (3.3 ± 3 point improvement, P < .001). There was a significant increase in mean SL (Δ3.43° ± 4.37°, P < .001) while LL (Δ0.17° ± 6.98°, P > .05) remained stable. Thirty-eight (52%) patients experienced lordosing MI-TLIFs, compared to 4 (5%) kyphosing and 31 (43%) neutral MI-TLIFs. A lower preoperative SL and more anterior cage placement were associated with the greatest improvement in SL (ß = -.45° P = .001, ß = 15.06° P < .001, respectively). CONCLUSIONS: In our series, the majority of patients experienced lordosing or neutral MI-TLIFs (n = 69, 95%). Preoperative radiographic alignment and anterior cage placement were significantly associated with target SL following MI-TLIF.

Association of upper-limb neurological recovery with functional outcomes in high cervical spinal cord injury.

OBJECTIVE: High cervical spinal cord injury (SCI) results in complete loss of upper-limb function, resulting in debilitating tetraplegia and permanent disability. Spontaneous motor recovery occurs to varying degrees in some patients, particularly in the 1st year postinjury. However, the impact of this upper-limb motor recovery on long-term functional outcomes remains unknown. The objective of this study was to characterize the impact of upper-limb motor recovery on the degree of long-term functional outcomes in order to inform priorities for research interventions that restore upper-limb function in patients with high cervical SCI. METHODS: A prospective cohort of high cervical SCI (C1-4) patients with American Spinal Injury Association Impairment Scale (AIS) grade A-D injury and enrolled in the Spinal Cord Injury Model Systems Database was included. Baseline neurological examinations and functional independence measures (FIMs) in feeding, bladder management, and transfers (bed/wheelchair/chair) were evaluated. Independence was defined as score ≥ 4 in each of the FIM domains at 1-year follow-up. At 1-year follow-up, functional independence was compared among patients who gained recovery (motor grade ≥ 3) in elbow flexors (C5), wrist extensors (C6), elbow extensors (C7), and finger flexors (C8). Multivariable logistic regression evaluated the impact of motor recovery on functional independence in feeding, bladder management, and transfers. RESULTS: Between 1992 and 2016, 405 high cervical SCI patients were included. At baseline, 97% of patients had impaired upper-limb function with total dependence in eating, bladder management, and transfers. At 1 year of follow-up, the largest proportion of patients who gained independence in eating, bladder management, and transfers had recovery in finger flexion (C8) and wrist extension (C6). Elbow flexion (C5) recovery had the lowest translation to functional independence. Patients who achieved elbow extension (C7) were able to transfer independently. On multivariable analysis, patients who gained elbow extension (C7) and finger flexion (C8) were 11 times more likely to gain functional independence (OR 11, 95% CI 2.8-47, p < 0.001) and patients who gained wrist extension (C6) were 7 times more likely to gain functional independence (OR 7.1, 95% CI 1.2-56, p = 0.04). Older age (≥ 60 years) and motor complete SCI (AIS grade A-B) reduced the likelihood of gaining independence. CONCLUSIONS: After high cervical SCI, patients who gained elbow extension (C7) and finger flexion (C8) had significantly greater independence in feeding, bladder management, and transfers than those with recovery in elbow flexion (C5) and wrist extension (C6). Recovery of elbow extension (C7) also increased the capability for independent transfers. This information can be used to set patient expectations and prioritize interventions that restore these upper-limb functions in patients with high cervical SCI.

Current and future applications of mobile health technology for evaluating spine surgery patients: a review.

Mobile health (mHealth) technology has assumed a pervasive role in healthcare and society. By capturing real-time features related to spine health, mHealth assessments have the potential to transform multiple aspects of spine care. Yet mHealth applications may not be familiar to many spine surgeons and other spine clinicians. Consequently, the objective of this narrative review is to provide an overview of the technology, analytical considerations, and applications of mHealth tools for evaluating spine surgery patients. Reflecting their near-ubiquitous role in society, smartphones are the most commonly available form of mHealth technology and can provide measures related to activity, sleep, and even social interaction. By comparison, wearable devices can provide more detailed mobility and physiological measures, although capabilities vary substantially by device. To date, mHealth evaluations in spine surgery patients have focused on the use of activity measures, particularly step counts, in an attempt to objectively quantify spine health. However, the correlation between step counts and patient-reported disease severity is inconsistent, and further work is needed to define the mobility metrics most relevant to spine surgery patients. mHealth assessments may also support a variety of other applications that have been studied less frequently, including those that prevent postoperative complications, predict surgical outcomes, and serve as motivational aids to patients. These areas represent key opportunities for future investigations. To maximize the potential of mHealth evaluations, several barriers must be overcome, including technical challenges, privacy and regulatory concerns, and questions related to reimbursement. Despite those obstacles, mHealth technology has the potential to transform many aspects of spine surgery research and practice, and its applications will only continue to grow in the years ahead.

Phased Array Beamforming Methods for Powering Biomedical Ultrasonic Implants.

Millimeter-scale implants using ultrasound (US) for power and communication have been proposed for a range of deep-tissue applications, including neural recording and stimulation. However, published implementations have shown high sensitivity to misalignment with the external US transducer. Ultrasonic beamforming using a phased array to these implants can improve tolerance to misalignment, reduce implant volume, and allow multiple implants to be operated simultaneously in different locations. This article details the design of a custom planar phased array US system, which is capable of steering and focusing US power within a 3-D volume. Analysis and simulation is performed to determine the choice of array element pitch, with special attention given to maximizing the power available at the implant while meeting FDA limits for diagnostic US. Time reversal (TR) is proposed as a computationally simple approach to beamforming that is robust despite scattering and inhomogeneity of the acoustic medium. This technique is demonstrated both in active drive and pulse-echo modes, and it is experimentally compared with other beamforming techniques by measuring energy transfer efficiency. Simultaneous power delivery to multiple implants is also demonstrated.

Behavioral deficits and cholinergic pathway abnormalities in male Sanfilippo B mice.

Sanfilippo B syndrome is a progressive neurological disorder caused by inability to catabolize heparan sulfate glycosaminoglycans. We studied neurobehavior in male Sanfilippo B mice and heterozygous littermate controls from 16 to 20 weeks of age. Affected mice showed reduced anxiety, with a decrease in the number of stretch-attend postures during the elevated plus maze (p=0.001) and an increased tendency to linger in the center of an open field (p=0.032). Water maze testing showed impaired spatial learning, with reduced preference for the target quadrant (p=0.01). In radial arm maze testing, affected mice failed to achieve above-chance performance in a win-shift working memory task (t-test relative to 50% chance: p=0.289), relative to controls (p=0.037). We found a 12.4% reduction in mean acetylcholinesterase activity (p<0.001) and no difference in choline acetyltransferase activity or acetylcholine in whole brain of affected male animals compared to controls. Cholinergic pathways are affected in adult-onset dementias, including Alzheimer disease. Our results suggest that male Sanfilippo B mice display neurobehavioral deficits at a relatively early age, and that as in adult dementias, they may display deficits in cholinergic pathways.