Approximately 150,000 children present each year to emergency departments (EDs) in the US with concussion and many more are treated by primary care physician, or outpatient specialists.

Concussion is defined as a traumatically induced transient disturbance of brain function and involves a complex pathophysiological process. There is a variety of symptoms related to concussion, and the diagnosis of concussion requires the use of symptom-checklist. Since there is a various degree of the severity of those symptoms, the diagnosis is a subjective one and lacks sensitivity.

One major problem is that approximately one-third of the children with concussion experience ongoing somatic, cognitive, and psychological or behavioral symptoms, referred to as persistent post-concussion symptoms. A recent study that investigated the validity a 12-point PPCS risk score revealed that it had modest validity (0.71). Moreover, one of the greatest concerns is the child's schedule return to activity.

Since the basic mechanism for concussion is acceleration/ deceleration movement of axons, it is likely to be expressed in desynchronization of delta wave activity between anterior hemispheres as seen in pathological problems related to attention and/ or working memory).

The aim of this proof-of-concept study is to find-out whether interhemispheric desynchronization of delta waves (IHDD) in the anterior hemispheres can identify acute concussion in children. If the investigators find that IHDD can accurately diagnose acute concussion, a second objective will be to examine whether this index can be a useful tool in the follow up of patients with persistent post-concussion symptoms.

Inclusion Criteria:

• Study group will include children aged 11-18 years with diagnosis of acute concussion based on the RPSQ. (Eisenberg et al., 2013; Harmon et al., 2013)
• Controls will be healthy children who will be admitted to the ED due to an isolated limb injury such as laceration, contusion or fracture and are not painful. Nonverbal or non-cooperative children will be excluded from the study.

Exclusion Criteria:

• Nonverbal or non-cooperative children.
• Lack of inform consent.

A prospective case control study will be performed. The investigators will enroll patients presented to the pediatric ED of Rambam Health Care Campus (RHCC) with symptoms of acute concussion within 24 hours of mild head injury). The control group will be consisted of previously healthy children with an isolated limb injury. Study participants will be enrolled on the basis of a convenience sample.