Prevalence and determinants of pain in chronic inflammatory demyelinating polyneuropathy: Results from the German INHIBIT registry.

BACKGROUND AND PURPOSE: Pain, fatigue and depression in chronic inflammatory demyelinating polyneuropathy (CIDP) are often underestimated, as the focus lies on sensorimotor dysfunction and gait instability. The aim of this study was to investigate their prevalence, characteristics and contribution to disability in a prospective cohort of 84 patients with CIDP. METHODS: Pain, fatigue, depression and quality of life were measured using the Pain Detect Questionnaire, Krupp's Fatigue Severity Scale, Beck Depression Inventory II and the German Short-Form 36 Health Survey. Sensorimotor deficits and disability were assessed using the Inflammatory Neuropathy Cause and Treatment overall disability score, the Rasch-built Overall Disability Scale, the Medical Research Council sum score and the Inflammatory Neuropathy Cause and Treatment sensory sum score. The interrelation between the five factors was assessed using analysis of variance and linear regression analysis. RESULTS: Pain was reported in 62%, mostly of moderate and severe intensity, whereas pain characteristics indicated neuropathic pain (NP) in 29%. Sensory dysfunction was stronger in NP patients compared to pain-free patients (p = 0.001). Pain of any type, especially NP, was associated with more pronounced fatigue symptoms (p = 0.010). Depressive symptoms were more frequent in patients with pain compared to the pain-free patients (61% vs. 33%, p = 0.02) and were more severe and frequent in NP than in non-NP patients (p = 0.005). Patients with pain had a worse physical quality of life than pain-free patients (p = 0.001). CONCLUSION: Pain, depression and fatigue are relevant disability factors in CIDP affecting quality of life. Sensory dysfunction is associated with NP. Therefore, evaluation of CIDP-related disability should include pain and sensory function for adequate monitoring of therapeutic interventions.

Increased muscle echointensity correlates with clinical disability and muscle strength in chronic inflammatory demyelinating polyneuropathy.

BACKGROUND AND PURPOSE: We evaluated muscle echointensity as a marker for secondary axonal damage in patients with chronic inflammatory demyelinating polyneuropathy (CIDP) using ultrasonography. Findings were correlated with clinical disability and muscular strength. METHODS: Eighty patients with CIDP (40 with typical and 40 with atypical CIDP) were examined clinically, including assessment of Medical Research Council (MRC) sum score and Inflammatory Neuropathy Cause and Treatment Overall Disability Sum Score (INCAT-ODSS). Echointensity in eight proximal and distal muscles of the arms and legs was evaluated by muscle ultrasonography using the Heckmatt scale. RESULTS: Alterations of echointensity occurred most frequently in the distal leg muscles, with a median (range) Heckmatt score of 1.5 (1-4). There were no differences between typical and atypical CIDP patients with regard to Heckmatt score. Alterations of echointensity correlated to disability and muscle strength. The arm score of the INCAT-ODSS correlated to Heckmatt score for the distal arm muscles (r = 0.23, p = 0.046) and the leg score of the INCAT-ODSS correlated to Heckmatt scores for the proximal (r = 0.34, p = 0.002) and distal leg muscles (r = 0.33, p = 0.004). MRC sum score, as well as individual MRC scores for arm and leg muscles, correlated to Heckmatt scores of the corresponding muscle groups (r = -0.25, p = 0.02 for MRC sum score). CONCLUSION: Increased muscle echointensity, reflecting fibrosis and fatty infiltration due to secondary axonal damage, correlated to muscular strength and disability in a large cohort of CIDP patients. Alterations of echointensity occur in both typical and atypical CIDP patients and are pronounced in the distal leg muscles.