Frequency of Asymptomatic Optic Nerve Enhancement in 203 Patients With MOG Antibody-Associated Disease.

BACKGROUND AND OBJECTIVES: Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is a distinct CNS demyelinating disease. The rate of asymptomatic optic nerve enhancement on MRI has not been explored in patients with MOGAD. An improved understanding of this would guide clinical practice and assessment of treatment efficacy. We aimed to determine the frequency of asymptomatic optic nerve enhancement in MOGAD. METHODS: This was a retrospective review of patients evaluated at Mayo Clinic with MOGAD between January 1, 2000, and August 1, 2021 (median follow-up 1.6 [range 1-19] years). MRI studies were reviewed by masked neuroradiologists. Scans performed within 30 days of ON attack were classified as attack scans. Images obtained for routine surveillance, before ON attack, or at the time of non-ON attack were classified as interattack scans. RESULTS: Five hundred sixty-six MRIs (203 unique patients, 53% female) were included. Interattack MRIs represented 341 (60%) of the scans (median 36 days post-ON [range -1,032 to 6,001]). Of the interattack scans, 43 of 341 (13%), 30 unique patients, showed optic nerve enhancement. The enhancement was located at prior sites of ON in 35 of 43 (81%). Among the 8 patients with enhancement in new optic nerve areas, 6 had acute disseminated encephalomyelitis without an eye examination at the time of the MRI and 2 had preceding ON without imaging. Long-term visual outcomes showed no significant difference between those with and without asymptomatic enhancement, with improved visual acuity in most patients. DISCUSSION: Asymptomatic optic nerve enhancement occurred in 13% of interattack MRIs, the majority in patients with prior ON and occurring at prior sites of optic nerve enhancement. New asymptomatic optic nerve enhancement in areas without prior ON was rare. These findings are important for understanding the natural history of MOGAD, the interpretation of symptoms or response to treatment, and the adjudication of attacks in clinical trials.

Population-Based Evaluation of Total Protein in Cerebrospinal Fluid.

OBJECTIVES: To present a normal range of cerebrospinal fluid (CSF) protein levels in a community-based population and to evaluate factors that contribute to CSF protein level variability. PATIENTS AND METHODS: Samples of CSF protein were obtained from participants aged 32 to 95 years who underwent lumbar puncture (LP) between November 1, 2007, and October 1, 2017, as part of the Mayo Clinic Study of Aging, a longitudinal, population-based study of residents of Olmsted County, Minnesota. RESULTS: A total of 633 participants (58.1% male; 99.1% White; mean ± SD age, 70.9±11.6 years) underwent LP with recorded CSF protein level. Mean ± SD CSF protein level was 52.2±18.4 mg/dL (to convert to mg/L, multiply by 10), with a 95% reference interval of 24.0 to 93.4 mg/dL (range, 14.0-148.0 mg/dL). Spinal stenosis and arterial hypertension were associated with higher CSF protein levels on univariable analysis (P<.001). Increasing age, male sex, and diabetes were all independently associated with higher CSF protein levels on multivariable analysis (P<.001). In the 66 participants with repeated LPs within 2.5 years, the coefficient of repeatability was 26.1 mg/dL. Eleven participants (16.7%) had a CSF protein level difference of 20 mg/dL or more between serial LPs, and 4 (6.1%) had a difference of 25 mg/dL or more. There was a trend toward greater CSF protein level variability in patients with spinal stenosis (P=.054). CONCLUSION: This large population-based study showed that CSF protein level can vary significantly among individuals. Elevated CSF protein level was independently associated with older age, male sex, and diabetes and is higher than listed in many laboratories. These findings emphasize the necessity of evidence-based reevaluation and standardization of CSF protein metrics.

Quantitative Assessment of Clinician Assistance During Dynamic Rehabilitation Using Force Sensitive Resistors.

Background: Neuromodulation using epidural electrical stimulation (EES) has shown functional restoration in humans with chronic spinal cord injury (SCI). EES during body weight supported treadmill training (BWSTT) enhanced stepping performance in clinical trial participants with paraplegia. Unfortunately, tools are lacking in availability to quantify clinician assistance during BWSTT with and without EES. Force sensitive resistors (FSRs) have previously quantified clinician assistance during static standing; however, dynamic tasks have not been addressed. Objective: To determine the validity of FSRs in measurements of force and duration to quantify clinician assistance and participant progression during BWSTT with EES in participants with SCI. Design: A feasibility study to determine the effectiveness of EES to restore function in individuals with SCI. Methods: Two male participants with chronic SCI were enrolled in a pilot phase clinical trial. Following implantation of an EES system in the lumbosacral spinal cord, both participants underwent 12 months of BWSTT with EES. At monthly intervals, FSRs were positioned on participants' knees to quantity forces applied by clinicians to achieve appropriate mechanics of stepping during BWSTT. The FSRs were validated on the benchtop using a leg model instrumented with a multiaxial load cell as the gold standard. The outcomes included clinician-applied force duration measured by FSR sensors and changes in applied forces indicating progression over the course of rehabilitation. Results: The force sensitive resistors validation revealed a proportional bias in their output. Loading required for maximal assist training exceeded the active range of the FSRs but were capable of capturing changes in clinician assist levels. The FSRs were also temporally responsive which increased utility for accurately assessing training contact time. The FSRs readings were able to capture independent stance for both participants by study end. There was minimal to no applied force bilaterally for participant 1 and unilaterally for participant 2. Conclusions: Clinician assistance applied at the knees as measured through FSRs during dynamic rehabilitation and EES (both on and off) effectively detected point of contact and duration of forces; however, it lacks accuracy of magnitude assessment. The reduced contact time measured through FSRs related to increased stance duration, which objectively identified independence in stepping during EES-enabled BWSTT following SCI.

Alterations of Spinal Epidural Stimulation-Enabled Stepping by Descending Intentional Motor Commands and Proprioceptive Inputs in Humans With Spinal Cord Injury.

Background: Regaining control of movement following a spinal cord injury (SCI) requires utilization and/or functional reorganization of residual descending, and likely ascending, supraspinal sensorimotor pathways, which may be facilitated via task-specific training through body weight supported treadmill (BWST) training. Recently, epidural electrical stimulation (ES) combined with task-specific training demonstrated independence of standing and stepping functions in individuals with clinically complete SCI. The restoration of these functions may be dependent upon variables such as manipulation of proprioceptive input, ES parameter adjustments, and participant intent during step training. However, the impact of each variable on the degree of independence achieved during BWST stepping remains unknown. Objective: To describe the effects of descending intentional commands and proprioceptive inputs, specifically body weight support (BWS), on lower extremity motor activity and vertical ground reaction forces (vGRF) during ES-enabled BWST stepping in humans with chronic sensorimotor complete SCI. Furthermore, we describe perceived changes in the level of assistance provided by clinicians when intent and BWS are modified. Methods: Two individuals with chronic, mid thoracic, clinically complete SCI, enrolled in an IRB and FDA (IDE G150167) approved clinical trial. A 16-contact electrode array was implanted in the epidural space between the T11-L1 vertebral regions. Lower extremity motor output and vertical ground reaction forces were obtained during clinician-assisted ES-enabled treadmill stepping with BWS. Consecutive steps were achieved during various experimentally-controlled conditions, including intentional participation and varied BWS (60% and 20%) while ES parameters remain unchanged. Results: During ES-enabled BWST stepping, the knee extensors exhibited an increase in motor activation during trials in which stepping was passive compared to active or during trials in which 60% BWS was provided compared to 20% BWS. As a result of this increased motor activation, perceived clinician assistance increased during the transition from stance to swing. Intentional participation and 20% BWS resulted in timely and purposeful activation of the lower extremities muscles, which improved independence and decreased clinician assistance. Conclusion: Maximizing participant intention and optimizing proprioceptive inputs through BWS during ES-enabled BWST stepping may facilitate greater independence during BWST stepping for individuals with clinically complete SCI. Clinical Trial Registration: ClinicalTrials.gov identifier: NCT02592668.