The sun had just risen as Dan Shelby began pedaling his bicycle down a main thoroughfare in Philadelphia. The computer programmer had to get to work early, and the traffic was still light. Seeing no oncoming cars, he quickly stuck out his arm as a signal and made an abrupt left onto the cross street.

He hadn't spotted the sedan already bounding up that road into the intersection, right at him. Dan's head crashed into the windshield, and he crumpled to the pavement, unconscious and bleeding.

This is how witnesses describe the accident of September 17, 2002 (names and locations of this real case have been changed). Despite the bike helmet, Shelby's brain was so damaged that he fell into a coma. He had severe craniocerebral trauma (CCT)--widespread injury to the brain and its nerves, especially to the frontal lobes. Half of all patients with severe CCT die within several hours. Many of those who do not will stay in the coma and, if they come out, may have serious losses of memory and other mental functions. Shelby's doctors did not know if he would emerge or what shape his brain would be in. Unfortunately, his case was not unique: bike, car and other violent accidents cause CCT in tens of thousands of victims each year.

Within hours Shelby's neurosurgeons recognized that the cyclist had suffered a frontal brain contusion with cerebral hemorrhage. They quickly began operating to relieve surging fluid and inflammation in the affected area. The fact that a pea-size gland deep in the interior of his head was also damaged escaped them. That oversight is more common than the medical community realizes. And it is an understandable lapse: after all, doctors are attempting to save these patients' lives; most hormonal glands are just not that critical.

What Wife?

After several surgeries, ongoing treatment in the intensive care unit stabilized Shelby's brain and body. He emerged from the coma after 20 days, and many weeks later he was transferred to a rehab clinic. There he could not remember the accident or anything from the days prior to it. He did remember what was going through his head when he first regained consciousness: he heard a small band playing Christmas music.

As rehab progressed, day by day Shelby felt as though his life was beginning again. Each bit of progress was a quiet triumph. But Shelby's wife had a hard time sharing his joy. Despite her daily visits, her husband did not recognize her. She was shocked when he asked who she was. Shelby's psychological functions were sluggish; his emotions seemed random. Such symptoms are common in CCT victims, and Mrs. Shelby tried to be patient, showing excitement as her husband learned to walk and brush his teeth again. After a trying six months, Shelby did manage to piece together some recognition of his family and former life. His doctors sent him home, and he looked forward to reestablishing relationships with his wife and two young daughters.

But the much anticipated normalcy did not return. The family experienced a husband and father who was a changed man. He was easily irritated yet dissolved into tears at the slightest conflict, and one morning he became so enraged that he threw his coffee cup at the wall. His wife found he had virtually no libido and could not keep an erection. After frustrating attempts to fire up their love life, the couple agreed to a platonic relationship.

During this period Shelby continued to go to rehab and started occupational therapy--mental exercises intended to gradually restore the capabilities he needed to resume his programming job. There he realized that he could barely concentrate. He frequently interrupted whichever therapist was speaking and then talked without stopping. He forgot what other people told him, and he got mad over minor hurdles.

Shelby's wife had an increasingly hard time handling her husband's change in personality. His memory of their relationship gradually returned, but he was still emotionally absent. She withdrew and, in the autumn of 2003, asked for a separation. Shortly thereafter Shelby moved into an apartment near downtown. Though sad, breakups are not uncommon after such a severe accident. Indeed, Shelby's case was somewhat typical for CCT patients. Damage to the frontal lobes in particular can lead to disorders in drive and behavior. Patients are virtually incapable of planning anything and have trouble judging the consequences of their own actions. They tend toward wild mood swings and, like little children, have a hard time controlling their anger. Many relationships cannot survive such a change.

Hormone Failure

A year after the accident Shelby began work again at his old company, on a reduced schedule. His co-workers were understanding; at first he was to focus on simple programs and small projects. But unlike before, the highly trained professional was no longer self-motivated and could not seem to figure out what needed to be done first. He had great difficulty completing his assignments.

Shelby asked his doctors frequently about his symptoms, but they told him the same thing each time: he was suffering from the usual late consequences of CCT. But Shelby could not reconcile himself to his condition. After two years he had had enough. His work was terrible; his sex life was unsatisfactory. He insisted to his doctors that something was not right. They readmitted him to a hospital.

Curious about the sexual dysfunction, doctors determined that Shelby had almost no testosterone, the male sex hormone. Surprised, they sent him for further hormone screening. The findings: several of his major glands were underproducing, and their deficiencies were all linked to the tiny pituitary gland at the foundation of his brain. This master gland releases hormones that command other glands and organs crucial to basic bodily functions. Low pituitary output was depressing Shelby's thyroid gland, in turn depressing his metabolism and making his emotions erratic. The sagging pituitary also suppressed his adrenal gland, leaving him fatigued, and limited his growth hormones, oddly enough reducing his concentration. And it cut his sex hormones, erasing his libido and triggering bouts of crying and depression. The doctors finally understood that the pituitary had been damaged in the accident, and it was releasing very little of the crucial messenger molecules that direct other hormonal systems of the body.

Because the pituitary gland is sheltered deep within the brain, physicians rarely think to look there for trauma. Until recently, it was the medical consensus that damage to the region was a rare complication of CCT, according to Guenter Stalla, an internist and neuroendocrinologist at the Max Planck Institute for Psychiatry in Munich. Few researchers had investigated this phenomenon, although a look back at the limited studies does show that people who died from CCT had impaired pituitary glands. And in recent investigations, researchers have found massive hormone disturbances in a third or more of CCT patients.

Stalla worries that many people who have recovered physically from CCT may be walking around with significant psychological, behavioral or relationship problems because their pituitary ills remain undiagnosed. Simple blood tests can determine if the master gland is compromised, but many physicians do not consider pituitary deficiencies because hormone levels do not play much of a role in the acute phase of treatment after an accident.

Furthermore, hormone metabolism is almost always disturbed in the days following a severe accident, and the chaos does not necessarily have anything to do with trauma to the pituitary. For example, most women miss their menstrual cycle after CCT or other major head injuries. The production of thyroid hormones or growth hormones can also be inhibited because the brain cuts back on all metabolic processes that are not crucial to life. Generally, however, the body starts producing these hormones again after a few weeks.

Shelby's doctors might have been unconsciously figuring on that very trend. But ignoring a hormone deficiency could have fatal consequences, leaving the body unable to handle severe stress and perhaps allowing a traumatically sick person to die of shock, Stalla warns. Stalla and other neurologists are beginning to study how a doctor can recognize whether a patient is suffering from a debilitating pituitary disturbance. So far the investigators have found abnormally low levels of at least one hormone group in five of 17 head trauma patients, indicating that pituitary insufficiency may be more frequent than previously thought. In response, Stalla recommends that physicians test hormone levels of patients three months after an accident. Monthly tests thereafter may help rule in or rule out pituitary damage.

Once Shelby's hormone trouble had been diagnosed, he was given thyroid hormones, growth hormones, cortisol and sex hormones, and doctors continue to monitor those levels regularly to this day. Shelby says he has finally gotten back his original zest for life. And even though he sometimes notices mental limitations, he says he is also his old self at work again. He socializes in the evening, meets friends, plays sports and sees his daughters often. Now 40, Shelby has not yet found a new partner. But he is happy to be leading a nearly normal life. He is even riding to work, more cautiously, on his bike again.