Pain
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Multicenter Study
The migraine eye: distinct rod-driven retinal pathways' response to dim light challenges the visual cortex hyperexcitability theory.
Migraine-type photophobia, most commonly described as exacerbation of headache by light, affects nearly 90% of the patients. It is the most bothersome symptom accompanying an attack. Using subjective psychophysical assessments, we showed that migraine patients are more sensitive to all colors of light during ictal than during interictal phase and that control subjects do not experience pain when exposed to different colors of light. ⋯ Unexpectedly, it was the amplitude of the retinal rod-driven b wave, which was consistently larger (by 14%-19% in the light-adapted and 18%-34% in the dark-adapted flash ERG) in the migraineurs than in the controls, rather than the retinal cone-driven a wave or the visual-evoked potentials that differs most strikingly between the 2 groups. Mechanistically, these findings suggest that the inherent hypersensitivity to light among migraine patients may originate in the retinal rods rather than retinal cones or the visual cortex. Clinically, the findings may explain why migraineurs complain that the light is too bright even when it is dim to the extent that nonmigraineurs feel as if they are in a cave.
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Multicenter Study
PRISM: a brief screening tool to identify risk in parents of youth with chronic pain.
Having a child with chronic pain impacts a parent's life. Reciprocally, parent cognitive, affective, and behavioral responses to the child's chronic pain can influence the child's pain experience. The purpose of this study is to develop a brief self-report screening tool (Parent Risk and Impact Screening Measure [PRISM]) of parent psychosocial functioning and behavioral responses to child pain. ⋯ Cutoff scores were determined to identify parents at differing levels of risk. The PRISM is a brief and clinically important means of screening parent distress and behaviors associated with child pain-related dysfunction. Further validation will use PRISM in longitudinal studies, particularly testing PRISM scores as a predictor of parent and child outcomes over time.
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Multicenter Study
A cross-sectional study investigating frequency and features of definitely diagnosed diabetic painful polyneuropathy.
This cross-sectional multicentre study aimed at investigating frequency and features of painful diabetic polyneuropathy. We consecutively enrolled 816 patients attending hospital diabetic outpatient clinics. We first definitely diagnosed diabetic polyneuropathy and pure small-fibre polyneuropathy using clinical examination, nerve conduction study, and skin biopsy or quantitative sensory testing. ⋯ Of the 816 patients, 36% had a diabetic polyneuropathy associated with male sex, age, and diabetes severity; 2.5% of patients had a pure small-fibre polyneuropathy, unrelated to demographic variables and diabetes severity. Of the 816 patients, 115 (13%) suffered from a painful polyneuropathy, with female sex as the only risk factor for suffering from painful polyneuropathy. In this large study, providing a definite diagnosis of diabetic polyneuropathy and pure small-fibre polyneuropathy, we show the frequency of painful polyneuropathy and demonstrate that this difficult-to-treat complication is more common in women than in men.
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Randomized Controlled Trial Multicenter Study
A randomised, placebo-controlled clinical trial with the α2/3/5 subunit selective GABAA positive allosteric modulator PF-06372865 in patients with chronic low back pain.
The effect of PF-06372865, a subtype-selective positive allosteric modulator of the γ-aminobutyric acid type A (GABAA) receptor, on chronic low back pain was investigated in a randomised, placebo- and active-controlled phase 2 clinical trial. The parallel treatment group trial consisted of a 1-week single-blind placebo run in the phase, followed by 4-week double-blind treatment. Patients were randomised to receive either PF-06372865, naproxen, or placebo twice a day for 4 weeks. ⋯ PF-06372865 was well tolerated. The most common treatment-related adverse events in the PF-06372865 arm were somnolence (5 mild and 4 moderate), dizziness (2 mild and 3 moderate), and nausea (2 mild). Although the reason for the lack of analgesic effect is not completely clear, it may be a result of not achieving sufficient receptor occupancy to drive efficacy.
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Randomized Controlled Trial Multicenter Study
Efficacy of the Nav1.7 blocker PF-05089771 in a randomised, placebo-controlled, double-blind clinical study in subjects with painful diabetic peripheral neuropathy.
The effect of PF-05089771, a selective, peripherally restricted Nav1.7 sodium channel blocker on pain due to diabetic peripheral neuropathy was investigated in a randomised, placebo and active-controlled parallel group clinical trial (NCT02215252). A 1-week placebo-run in the period was followed by a 4-week treatment period and a 1-week placebo run-out/taper-down period. Single-blind placebo was administered throughout run-in and run-out periods. ⋯ As predefined efficacy criteria were not met, the study did not proceed to the second part. PF-05089771 was well tolerated. Possible reasons for the modest efficacy observed with PF-05089771 are discussed.