Mild Traumatic Brain Injury (TBI) has a well defined neuropathology. The natural history of recovery is well understood. The appropriate somatic and psychological treatments are known. Nevertheless, a subset of patients do not recover and may even worsen with time-the persistent post concussive syndrome (PPCS). They are frequently involved in litigation. The risk factors for PPCS are known, and management strategies are available. There is a great risk of inappropriately attributing PPCS to direct neurological injury that cannot be supported by any objective measure. The symptoms and the cognitive deficits in these patients, even when defined by ostensibly objective testing, have no specificity. Accurately distinguishing among the many possible diagnoses in these patients is critical to avoid iatrogenic disability and incorrect treatment.