title: The probability of spontaneous regression of lumbar herniated disc: a systematic review.
abstract: OBJECTIVE
  To determine the probability of spontaneous disc regression among each type of lumbar herniated disc, using a systematic review.
  
  
  METHODS
  Medline, Cochrane Library, CINAHL, and Web of Science were searched using key words for relevant original articles published before March 2014. Articles were limited to those published in English and human studies.
  
  
  METHODS
  Articles had to: (1) include patients with lumbar disc herniation treated conservatively; (2) have at least two imaging evaluations of the lumbar spine; and (3) exclude patients with prior lumbar surgery, spinal infections, tumors, spondylolisthesis, or spinal stenosis. Two reviewers independently extracted study details and findings. Thirty-one studies met the inclusion criteria. Furthermore, if the classification of herniation matched the recommended classification of the combined Task Forces, the data were used for combined analysis of the probability of disc regression of each type. Nine studies were applicable for probability calculation.
  
  
  RESULTS
  The rate of spontaneous regression was found to be 96% for disc sequestration, 70% for disc extrusion, 41% for disc protrusion, and 13% for disc bulging. The rate of complete resolution of disc herniation was 43% for sequestrated discs and 15% for extruded discs.
  
  
  CONCLUSIONS
  Spontaneous regression of herniated disc tissue can occur, and can completely resolve after conservative treatment. Patients with disc extrusion and sequestration had a significantly higher possibility of having spontaneous regression than did those with bulging or protruding discs. Disc sequestration had a significantly higher rate of complete regression than did disc extrusion.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Wan Fang Hospital, Taipei Medical University, Taiwan.
authors.forename: Chun-Chieh
authors.initials: CC
authors.lastname: Chiu
authors.affiliation: Department of Orthopedic Surgery, Wan Fang Hospital, Taipei Medical University, Taiwan.
authors.forename: Tai-Yuan
authors.initials: TY
authors.lastname: Chuang
authors.affiliation: Department of Physical Medicine and Rehabilitation, Wan Fang Hospital, Taipei Medical University, Taiwan.
authors.forename: Kwang-Hwa
authors.initials: KH
authors.lastname: Chang
authors.affiliation: Department of Applied Mathematics, Chung-Yuan Christian University, Taiwan.
authors.forename: Chien-Hua
authors.initials: CH
authors.lastname: Wu
authors.affiliation: Department of Physical Medicine and Rehabilitation, Wan Fang Hospital, Taipei Medical University, Taiwan.
authors.forename: Po-Wei
authors.initials: PW
authors.lastname: Lin
authors.affiliation: Department of Physical Medicine and Rehabilitation, Wan Fang Hospital, Taipei Medical University, Taiwan quatcer@gmail.com.
authors.forename: Wen-Yen
authors.initials: WY
authors.lastname: Hsu
mesh_terms: D006801:Humans; D007405:Intervertebral Disc Displacement; D011336:Probability; D012075:Remission, Spontaneous
keywords: Low back pain; disc herniation; probability; regression of hernation; systematic review