Obese individuals have slowed conduction in the median nerve across the wrist, but the mechanism for this is not established. This case control study of 27 o bese subjects and 16 thin subjects was designed to test the...Obese individuals have slowed conduction in the median nerve across the wrist, but the mechanism for this is not established. This case control study of 27 o bese subjects and 16 thin subjects was designed to test the hypothesis that obes e individuals have higher carpal canal pressures and more median nerve swelling than thin individuals. Allsubjects were asymptomatic for hand symptoms, and had measurements of median and ulnar sensory nerve conduction in the nondominant han d, ultrasound measurement of the median nerve cross sectional area proximal to the carpalcanal, and carpal canal pressure measurement. There was no difference in age or gender ratio between the obese and thin groups. The median nerve cross sectional area was equal in the obese and thin groups (9.3 mm2 vs. 9.4 mm2), a s was the carpal canal pressure (16.2 mmHg vs. 15.5 mmHg, respectively). There w as a strong correlation between median nerve conduction slowing across the wrist and median nerve cross sectional area at the wrist (r = 0.55, P = 0.002). Obes ity does not influence carpal canal pressure or the size of the median nerve at the wrist. However, t here is a strong association between slowed median nerve conduction and increase d nerve size which suggests endoneurial edema as a metabolic mechanism; the cond uction slowing does not appear to be related to mechanical stress.展开更多
Objective: Patients with Chronic Low Back Pain (CLBP) show arousal, attentiona l and cognitive disturbances. The sleep state dependent P50 midlatency auditory evoked potential was used to determine if patients with CL...Objective: Patients with Chronic Low Back Pain (CLBP) show arousal, attentiona l and cognitive disturbances. The sleep state dependent P50 midlatency auditory evoked potential was used to determine if patients with CLBP [with and without c o-morbid depression (DEP)] show quantitative disturbances in the manifestation of the P50 potential. Methods: P50 potential latency,amplitude and habituation t o repetitive stimuli at 250,500and 1000 ms interstimulus intervals (ISIs) was re corded, along with the McGill Pain Questionnaire-Short Form (MPQ-SF).CLBP subj ects (n=42) were compared with Controls (n=43), and with subjects with DEP only (n=6). Of the CLBP subjects, 20/42 had clinical depression (CLBP+DEP); 8/20 wer e taking anti-depressant medication (CLBP+DEP+med), the others were not (CLBP +DEP-med). Results: There were no differences (ANOVA) in age, sex or P50 poten tial latency, although there was a trend towards increased latencies in CLBP gro ups. P50 potential amplitude was lower in CLBP groups, but not in sub-groups, a gain indicating a trend. P50 potential habituation was decreased in the DEP only subjects at the 250 m ISI, and decreased in CLBP+DEPmed subjects at the 500 ms ISI. This difference was not present in CLBP+DEP+med subjects. The MPQ-SF re vealed that patients with CLBP and CLBP+DEP-med showed lower pain scores than CLBP+DEP+med patients. Conclusions: There is decreased habituation of the P50 potential habituation in unmedicated patients with CLBP+DEP compared to C ontrols.Significance: Patients with CLBP+DEP-med may be less able to disregard incoming sensory information, including painful sensations, but anti-depressan t medications help correct this deficit. However, their perception of pain may b e increased by medication.展开更多
文摘Obese individuals have slowed conduction in the median nerve across the wrist, but the mechanism for this is not established. This case control study of 27 o bese subjects and 16 thin subjects was designed to test the hypothesis that obes e individuals have higher carpal canal pressures and more median nerve swelling than thin individuals. Allsubjects were asymptomatic for hand symptoms, and had measurements of median and ulnar sensory nerve conduction in the nondominant han d, ultrasound measurement of the median nerve cross sectional area proximal to the carpalcanal, and carpal canal pressure measurement. There was no difference in age or gender ratio between the obese and thin groups. The median nerve cross sectional area was equal in the obese and thin groups (9.3 mm2 vs. 9.4 mm2), a s was the carpal canal pressure (16.2 mmHg vs. 15.5 mmHg, respectively). There w as a strong correlation between median nerve conduction slowing across the wrist and median nerve cross sectional area at the wrist (r = 0.55, P = 0.002). Obes ity does not influence carpal canal pressure or the size of the median nerve at the wrist. However, t here is a strong association between slowed median nerve conduction and increase d nerve size which suggests endoneurial edema as a metabolic mechanism; the cond uction slowing does not appear to be related to mechanical stress.
文摘Objective: Patients with Chronic Low Back Pain (CLBP) show arousal, attentiona l and cognitive disturbances. The sleep state dependent P50 midlatency auditory evoked potential was used to determine if patients with CLBP [with and without c o-morbid depression (DEP)] show quantitative disturbances in the manifestation of the P50 potential. Methods: P50 potential latency,amplitude and habituation t o repetitive stimuli at 250,500and 1000 ms interstimulus intervals (ISIs) was re corded, along with the McGill Pain Questionnaire-Short Form (MPQ-SF).CLBP subj ects (n=42) were compared with Controls (n=43), and with subjects with DEP only (n=6). Of the CLBP subjects, 20/42 had clinical depression (CLBP+DEP); 8/20 wer e taking anti-depressant medication (CLBP+DEP+med), the others were not (CLBP +DEP-med). Results: There were no differences (ANOVA) in age, sex or P50 poten tial latency, although there was a trend towards increased latencies in CLBP gro ups. P50 potential amplitude was lower in CLBP groups, but not in sub-groups, a gain indicating a trend. P50 potential habituation was decreased in the DEP only subjects at the 250 m ISI, and decreased in CLBP+DEPmed subjects at the 500 ms ISI. This difference was not present in CLBP+DEP+med subjects. The MPQ-SF re vealed that patients with CLBP and CLBP+DEP-med showed lower pain scores than CLBP+DEP+med patients. Conclusions: There is decreased habituation of the P50 potential habituation in unmedicated patients with CLBP+DEP compared to C ontrols.Significance: Patients with CLBP+DEP-med may be less able to disregard incoming sensory information, including painful sensations, but anti-depressan t medications help correct this deficit. However, their perception of pain may b e increased by medication.
