Post-concussion syndrome
Though no universally accepted definition of postconcussive syndrome exists, most of the literature defines the syndrome as the development of at least 3 of the following symptoms: headache, dizziness, fatigue, irritability, impaired memory and concentration, insomnia, and lowered tolerance for noise and light. One complication in diagnosis is that symptoms of PCS also occur in people who have no history of head injury, but who have other medical and psychological complaints. In one study 64% of people with TBI, 11% of those with brain injuries, and 7% of those with other injuries met the DSM-IV criteria for post-concussion syndrome. Many of these PCS sufferers were misdiagnosed as having other unrelated conditions due to commonality of symptoms. (see diagnosis, below).
Post-concussion syndrome
PCS, which shares symptoms with a variety of other conditions, is highly likely to be misdiagnosed in people with these conditions. Cognitive and affective symptoms that occur following a traumatic injury may be attributed to mTBI, but in fact be due to another factor such as post-traumatic stress disorder, which is easily misdiagnosed as PCS and vice versa. Affective disorders such as depression have some symptoms that can mimic those of PCS and lead to a wrongful diagnosis of the latter; these include problems with concentration, emotional lability, anxiety, and sleep problems. Depression, which is highly common in persistent PCS, can worsen other PCS symptoms, such as headaches and problems with concentration, memory, and sleep. PCS also shares symptoms with chronic fatigue syndrome, fibromyalgia, and exposure to certain toxins. Traumatic brain injury may cause damage to the hypothalamus or the pituitary gland, and deficiencies of pituitary hormones (hypopituitarism) can cause similar symptoms to post-concussion syndrome; in these cases, symptoms can be treated by replacing any hormones that are deficient.