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J Neurotrauma. 2017 Apr 15;34(8):1511-1523. doi: 10.1089/neu.2016.4677. Epub 2016 Nov 29.

Longitudinal Study of Postconcussion Syndrome: Not Everyone Recovers.

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1 Division of Neurosurgery, University of Toronto and Toronto Western Hospital , Toronto, Ontario, Canada .
2 Canadian Concussion Center , Toronto Western Hospital, Toronto, Canada .
3 Division of Neurology, University of Toronto and Toronto Western Hospital , Toronto, Ontario, Canada .
4 Division of Neuroradiology, University of Toronto and Toronto Western Hospital , Toronto, Ontario, Canada .
5 Department of Laboratory Medicine and Pathobiology, University of Toronto , Toronto, Ontario, Canada .


We examined recovery from postconcussion syndrome (PCS) in a series of 285 patients diagnosed with concussion based on international sport concussion criteria who received a questionnaire regarding recovery. Of 141 respondents, those with postconcussion symptoms lasting less than 3 months, a positive computed tomography (CT) and/or magnetic resonance imaging (MRI), litigants, and known Test of Memory Malingering (TOMM)-positive cases were excluded, leaving 110 eligible respondents. We found that only 27% of our population eventually recovered and 67% of those who recovered did so within the first year. Notably, no eligible respondent recovered from PCS lasting 3 years or longer. Those who did not recover (n = 80) were more likely to be non-compliant with a do-not-return-to-play recommendation (p = 0.006) but did not differ from the recovered group (n = 30) in other demographic variables, including age and sex (p ≥ 0.05). Clustergram analysis revealed that symptoms tended to appear in a predictable order, such that symptoms later in the order were more likely to be present if those earlier in the order were already present. Cox proportional hazards model analysis showed that the more symptoms reported, the longer the time to recovery (p = 7.4 × 10-6), with each additional symptom reducing the recovery rate by approximately 20%. This is the first longitudinal PCS study to focus on PCS defined specifically as a minimum of 3 months of symptoms, negative CT and/or MRI, negative TOMM test, and no litigation. PCS may be permanent if recovery has not occurred by 3 years. Symptoms appear in a predictable order, and each additional PCS symptom reduces recovery rate by 20%. More long-term follow-up studies are needed to examine recovery from PCS.


definitions, eligibility, and exclusions; number of symptoms; postconcussion syndrome; recovery

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