More than 1 million people suffer minor traumatic brain injuries in the United States each year. Depending on the definitions used and population examined, approximately 50 percent of patients with minor traumatic brain injury have symptoms of post-concussive syndrome at 1 month and 15 percent have symptoms at 1 year. While men experience minor traumatic brain injury more frequently than women, the incidence of post-concussive syndrome is greater in females than in males. Fifty percent of those who experience minor traumatic brain injury are aged 15-34 years. However, post-concussive syndrome has no predilection for any specific age group.
The Mayo Clinic staff defines post-concussion syndrome as a complex disorder in which a combination of post-concussion symptoms — such as headaches and dizziness — last for weeks and sometimes months after the injury that caused the concussion.
Concussion is a mild traumatic brain injury, usually occurring after a blow to the head. Loss of consciousness isn't required for a diagnosis of concussion or post-concussion syndrome. In fact, the risk of post-concussion syndrome doesn't appear to be associated with the severity of the initial injury.
In most people, post-concussion syndrome symptoms occur within the first seven to 10 days and go away within three months, though they can persist for a year or more. Post-concussion syndrome treatments are aimed at easing specific symptoms.
In general, post-concussion syndrome usually involves headache and other pain, dizziness or light lightheadedness, memory and concentration difficulty, amnesia, sleep disturbance, frustration and irritability, periods of confusion or mental dullness, emotional and behavioral changes, loss of self-confidence, fatigue and weakness, tinnitus, visual distortions and slow reactions.
Since no abnormalities are usually found on routine neurological examination for mild traumatic brain injury, post-concussion syndrome is often overlooked or under diagnosed.
Other researchers suggest that this definition lacks empirical support.
There are two current sets of research criteria for the post-concussive disorder: the International Classification of Diseases, 10th Edition (ICD-10), and the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV).
According to the ICD-10 , a person must have a history of “head trauma with loss of consciousness” preceding the onset of symptoms by a period of up to 4 weeks and at least three of six symptom categories. These include:
Careful evaluation with laboratory techniques (electroencephalography, brain stem-evoked potentials, brain imaging, and oculonystagmography) may yield objective evidence to substantiate the symptoms, but results are often negative. The complaints are not necessarily associated with compensation motives. The ICD-10 criteria do not require “objective” evidence of cognitive problems.
The DSM-IV research criteria for the post-concussional disorder says the individual must show objective evidence on neuropsychologic testing of declines in some of his or her cognitive abilities, such as attention, concentration, learning, or memory. The patient must also report three or more subjective symptoms from category C, and these symptoms must be present for at least 3 months. The category C symptoms are:
The DSM-IV includes the additional criteria: “The disturbance causes significant impairment in social or occupational functioning and represents a significant decline in the previous level of functioning.”
Studies have found large diagnostic differences emerge when the ICD-10 and DSM-IV criteria are compared in the same set of patients. This is because the DSM-IV criteria require neurocognitive impairment and impairment in important role functioning. The ICD-10 does not have these “impairment” criteria. Researchers have reported that consecutive patients with mild traumatic brain injuries seen at a level 1 trauma center and followed prospectively have relatively low rates of diagnosis at three months post-injury using the DSM-IV criteria (11 percent to 17 percent), compared with the ICD-10 criteria (54 percent to 64 percent).
Researchers suggest the most serious and obvious problem with the ICD-10 and the DSM-IV criteria for the post-concussive disorder is causally linking the subjective, self-reported symptoms to the original mild traumatic brain injury. These researchers suggest there has never been agreement on the explicit etiology of the so-called persistent post-concussive disorder. The symptoms that comprise the diagnostic criteria, these researchers content, are nonspecific and occur frequently in healthy adults and in a variety of patient groups who have not suffered any mild traumatic brain injury.
In this debate over which symptoms of post-concussive syndrome are due to organic causes and which have a psychological basis, researchers have hypothesized that early post-concussive syndrome symptoms are more likely to be organic, whereas post-concussive syndrome symptoms that persist beyond 3 months have a nonorganic, psychological basis. While recent research has shown that psychological factors may be present early, other studies using imaging techniques such as magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT), and magnetoencephalography (MEG) have demonstrated the presence of organic brain injury in patients with persistent post-concussive syndrome at greater than 1 year after injury.
Neuropsychological assessments have pointed toward an organic basis for some of the symptoms of post-concussive syndrome. Patients with post-concussive syndrome have been found to have cognitive deficits in memory, attention, and learning when compared with controls. Findings from neuropsychological evaluations demonstrate that symptom severity is not necessarily dependent on neurologic status immediately following injury. However, in some series, the length of loss of consciousness or post-traumatic amnesia may be correlated with the probability of developing post-concussive syndrome.
A study of patients who developed post-concussive syndrome from a mild traumatic brain injury found no correlation between pursuit of litigation and the injury. In fact, the study found post-concussive syndrome symptoms persisted after settlement.
Some authors have concluded that people with a history of depressive and anxiety disorders, certain personality types, or poor coping skills may be predisposed to post-concussive syndrome, but the data are conflicting.
Outpatient care is the cornerstone of treatment of patients with post-concussive syndrome and involves multidisciplinary teams that provide testing and treatment, including cognitive rehabilitation, psychotherapy, stress management, vocational counseling, and symptomatic treatment with medications.