Identifying children most likely to have persistent neurological symptoms following concussion remains a largely hit-or-miss proposition, a systematic literature review suggested.
After reviewing 15 studies that attempted to find predictive factors for persistent concussion symptoms, Roger Zemek, MD, of Children's Hospital of Eastern Ontario in Ottawa, and colleagues found no consistent pattern in the results.
"Minimal, and at times contradictory evidence exists to associate clinically available factors with eventual development of persistent concussion symptoms in children," they wrote online in JAMA Pediatrics, the journal formerly known as Archives of Pediatric and Adolescent Medicine.
"Because there is no method to predict which children will experience prolonged symptoms versus which will have a rapid recovery, clinicians must continue to recommend conservative management including both cognitive and physical rest, followed by a stepwise return to activities for all children."
Zemek and colleagues added that "a multicenter prospective study" is needed to identify factors that could distinguish low-risk from high-risk cases.
"Research to improve care of pediatric concussion depends on early identification of those most in need of intervention," they argued.
The major problem with the existing studies was what Zemek and colleagues called "excessive heterogeneity" in methods, including patient inclusion and exclusion criteria, definition of concussion, and instruments for measuring post-concussion symptoms.
Such heterogeneity extended beyond the studies they reviewed. The ICD-10 diagnostic system, for example, defines persistent concussion symptoms as those present 1 month after injury, whereas the DSM-IV classification of psychiatric conditions requires symptoms to persist for 3 months.
Zemek and colleagues also pointed to the large array of instruments for measuring persistent symptoms. Ten different assessment tools were used in the 15 studies included in the review.
Starting with 561 published studies on concussion in children, Zemek and colleagues threw out all but 15 for failing to provide data on all of the following clinical factors:
- Medical history including previous concussion
- Comorbidities including mental health, psychosocial stressors, and coping skills
- Medication use at presentation
- Mechanism of injury
- Symptom presence and severity at initial presentation
Enrollment in the 15 studies ranged from 34 to 867; most included control participants who had not suffered head injuries. Controls included healthy siblings as well as children with other types of injuries or illnesses.
Because of the heterogeneity in the 15 studies selected for inclusion, the researchers decided a pooled meta-analysis was impossible.
Nevertheless, some clues to potential predictors could be gleaned from the studies, Zemek and colleagues suggested.
"[Two] larger prospective studies concluded that the risk for developing persistent concussion symptoms was increased in older children with a history of loss of consciousness and either headache or nausea/vomiting," they found.
"Several smaller studies also noted that initial dizziness may be predictive of prolonged symptoms. While many studies excluded patients with a history of head injury, learning difficulties, or behavioral problems, one study that did not exclude these patients concluded that these pre-morbid conditions also increased risk."
Zemek and colleagues added that they could not reach "clear conclusions" on factors potentially associated with safe resumption of normal activities such as school and sports.