ACEREBRAL concussion, whatever the cause, means that a person's brain has been shaken violently within the frame of the skull. For practical purposes, this head injury can be classified as a minor, moderate, or severe concussion. Cases classified as minor concussions are those in which there is usually no open, penetrating wound into the scalp, skull, or meninges, nor is the skull fractured. Unconsciousness, for a short time, is always present. In laymen's terms, such a concussion means that the individual is temporarily "knocked out." Even though such an injury is not ordinarily considered serious, complications often result. The symptoms of a minor concussion are usually not too severe. The patient is always unconscious, the time varying anywhere from a few minutes up to an hour or so. When the patient awakens, he may at first be somewhat disoriented, and may complain of headache and dizziness, especially when he changes position. The patient's pulse is rapid at first, but generally slows down in a short time. The blood pressure is on the low side but returns to normal along with the pulse. There is usually little or no elevation of temperature. The patient may vomit, and continued vomiting might indicate intracranial bleeding.