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).
Posterior cortical atrophy
There is no standard definition of PCA and no established diagnostic criteria, so it is not possible to know how many people have the condition. Some studies have found that about 5 percent of people diagnosed with Alzheimer’s disease have PCA. However, because PCA often goes unrecognized, the true percentage may be as high as 15 percent. Researchers and physicians are working to establish a standard definition and diagnostic criteria for PCA.