Cognitive processing speed in multiple sclerosis clinical practice: association with patient-reported outcomes, employment and magnetic resonance imaging metrics.

BACKGROUND AND PURPOSE: To analyze the relationship between cognitive processing speed, patient-reported outcome measures (PROMs), employment and magnetic resonance imaging (MRI) metrics in a large multiple sclerosis cohort. METHODS: Cross-sectional clinical data, PROMs, employment and MRI studies within 90 days of completion of the Processing Speed Test (PST), a technology-enabled adaptation of the Symbol Digit Modalities Test, were collected. MRI was analyzed using semi-automated methods. Correlations of PST score with PROMs and MRI metrics were examined using Spearman's rho. Wilcoxon rank sum testing compared MRI metrics across PST score quartiles and linear regression models identified predictors of PST performance. Effects of employment and depression were also investigated. RESULTS: In 721 patients (mean age 47.6 ± 11.4 years), PST scores were significantly correlated with all MRI metrics, including cord atrophy and deep gray matter volumes. Linear regression demonstrated self-reported physical disability, cognitive function, fatigue and social domains (adjusted R2  = 0.44, P < 0.001) as the strongest clinical predictors of PST score, whereas that of MRI variables included T2 lesion volume, whole-brain fraction and cord atrophy (adjusted R2  = 0.42, P < 0.001). An inclusive model identified T2 lesion volume, whole-brain fraction, self-reported upper extremity function, cognition and social participation as the strongest predictors of PST score (adjusted R2  = 0.51, P < 0.001). There was significant effect modification by depression on the relationship between self-reported cognition and PST performance. Employment status was associated with PST scores independent of age and physical disability. CONCLUSION: The PST score correlates with PROMs, MRI measures of focal and diffuse brain injury, and employment. The PST score is a feasible and meaningful measure for routine multiple sclerosis care.

Long-term effects of intravenous immunoglobulin in CIDP.

OBJECTIVE: Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an acquired demyelinating disease of the peripheral nervous system characterized by muscle weakness, areflexia or hyporeflexia, and sensory disturbances. Although short-term efficacy of intravenous immunoglobulin (IVIg) has been demonstrated in randomized-controlled trials, the data pertaining to long-term outcome in CIDP are limited. Consequently, the aim of the present study was to assess the long-term effects of IVIg on neurophysiological parameters in CIDP. METHODS: Neurophysiological records from 11 CIDP patients, treated with IVIg for 12 months, were reviewed. Nerve conduction studies were assessed at baseline, 1-year, and last follow-up. RESULTS: There was a significant reduction in the frequency of conduction blocks (pre-treatment nerve segments affected 61%; last follow-up 39%, P<0.01) and a reduction in ongoing axonal loss (pre-treatment regions with spontaneous activity, 47%; post-treatment 29%, P<0.01) with IVIg treatment. Further, there was significant improvement in sensory nerve conduction studies with IVIg treatment (sensory amplitudes reduced pre-treatment, 90% nerves tested; post-treatment, 62%, P<0.01). CONCLUSIONS: The present study suggests that long-term IVIg maintenance therapy improves neurophysiological parameters in CIDP. However, CIDP patients remain IVIg dependent and new conduction blocks may develop. SIGNIFICANCE: The present study suggests that long-term IVIg maintenance therapy improves neurophysiological parameters in CIDP, possibly by reducing the immune response and thereby fostering nerve healing.