title: Dysfunction of Nucleus Accumbens Is Associated With Psychiatric Problems in Patients With Chronic Low Back Pain: A Functional Magnetic Resonance Imaging Study.
abstract: METHODS
  A cross-sectional study.
  
  
  OBJECTIVE
  The aim of this study was to evaluate activity of the nucleus accumbens (NAc) in response to lumbar mechanical stimulation in patients with chronic low back pain (cLBP) using functional magnetic resonance imaging (fMRI).
  
  
  BACKGROUND
  Although a modified activity of the NAc was characterized in cLBP patients, its pathological significance has yet to be determined. We hypothesized that NAc activation in response to pain might differ depending on the extent of psychiatric problems, which might be associated with the affective/motivational background of chronic pain.
  
  
  METHODS
  Twenty-one patients with cLBP (four men, 17 women) were recruited. Subjects were divided into two groups on the basis of scores on the patient version of the Brief Scale for Psychiatric problems in Orthopaedic Patients (BS-POP) scores: ≥17 (High Score, HiS group) and <17 (non-High Score, non-HiS group). Each subject was placed in the prone position on a 3-Tesla magnetic resonance imaging (MRI) scanner and stimulated by mechanical stimulation on the left lower back. Three blocks of 30-second pain stimulus calibrated at either 3 or 5 on an 11-grade numerical rating scale (NRS) were applied with intervening 30-second rest conditions during whole-brain echo-planar imaging. Functional images were analyzed using a multisubject general linear model with Bonferroni multiple comparisons.
  
  
  RESULTS
  Subjects in the HiS group had more intense daily pain and lower quality of life than those in the non-HiS group (P < 0.05). Catastrophic thinking in relation to pain experience did not differ between the groups. Activation at the NAc was smaller in the HiS group than in the non-HiS group (P < 0.001).
  
  
  CONCLUSIONS
  The presence of psychiatric problems was associated with attenuated activity of the NAc in cLBP patients. Dysfunction of the NAc might potentially be involved in the affective/motivational factors in the chronification of LBP.
  
  
  METHODS
  N/A.
authors.affiliation: Department of Orthopaedic Surgery, Fukushima Medical University School of Medicine, Fukushima, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Kaneko
authors.affiliation: Department of Anesthesiology and Pain Clinic, Tokyo Medical and Dental University Hospital of Medicine, Tokyo, Japan.
authors.forename: Shuo
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Orthopaedic Surgery, Fukushima Medical University School of Medicine, Fukushima, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Sekiguchi
authors.affiliation: Department of Orthopaedic Surgery, Fukushima Medical University School of Medicine, Fukushima, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Nikaido
authors.affiliation: Department of Anesthesiology and Pain Clinic, Tokyo Medical and Dental University Hospital of Medicine, Tokyo, Japan.
authors.forename: Koshi
authors.initials: K
authors.lastname: Makita
authors.affiliation: Department of Anesthesiology and Pain Clinic, Tokyo Medical and Dental University Hospital of Medicine, Tokyo, Japan.
authors.forename: Jiro
authors.initials: J
authors.lastname: Kurata
authors.affiliation: Department of Orthopaedic Surgery, Fukushima Medical University School of Medicine, Fukushima, Japan.
authors.forename: Shin-Ichi
authors.initials: SI
authors.lastname: Konno
mesh_terms: D000328:Adult; D058443:Catastrophization / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000523:psychology; D059350:Chronic Pain / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000523:psychology; D003430:Cross-Sectional Studies; D017352:Echo-Planar Imaging; D005260:Female; D006306:Health Surveys; D006801:Humans; D017116:Low Back Pain / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000523:psychology; D008279:Magnetic Resonance Imaging; D008297:Male; D008603:Mental Health; D008875:Middle Aged; D009714:Nucleus Accumbens / Q000000981:diagnostic imaging* / Q000503:physiopathology; D010147:Pain Measurement; D011788:Quality of Life / Q000523:psychology*; D012720:Severity of Illness Index; D055815:Young Adult