The choice to wear a helmet is yours, after all the head is yours. But it would be prudent to know as to what happens when the brain suffers damage. Our brain can withstand only a limited amount of traumatic damage. Beyond this the possibility of recovery becomes remote even with the best of treatment and efforts. Head injuries fall into two categories: external (usually scalp) injuries and internal head injuries, which may involve the skull, the blood vessels within the skull, or the brain. An internal head injury has more serious possible implications, since the skull serves as a natural protective helmet for the delicate brain. 

The scalp is rich with blood vessels, so even a minor cut to the scalp can bleed profusely. The "goose egg" or swelling that may appear on the scalp after a head blow results from the scalp's veins leaking fluid or blood into (and under) the scalp. It may take days or weeks to disappear. Any visible or suspected head injury requires immediate professional neurosurgical intervention. At times, the damage may not be apparent and tends to be ignored. This should not be so. If the person has lost consciousness, even momentarily, or there is the remotest possibility that the brain may have suffered even the minutest of damage, he should be immediately shifted to a medical facility. 

The brain is cushioned by cerebrospinal fluid, but a severe blow to the head may knock the brain into the side of the skull or tear the blood vessels. Any internal head injury - fractured skull, torn blood vessels, or damage to the brain itself - can be serious and may even be life-threatening. If the person shows any of the following symptoms: unconsciousness; abnormal breathing; obvious wound or fracture; bleeding from the nose, ear, or mouth; disturbance of speech or vision; pupils of unequal size; weakness or paralysis; dizziness; neck pain or stiffness; seizure; vomiting; loss of bladder or bowel control, things are in bad shape. Until help arrives, do not move the person unless absolutely necessary. 

If the person is unconscious or dazed, or there is any paralysis, do not move him at all - there may be injury to the spine. Place your hands on either side of his head, and keep him in the position in which you found him. If he vomits, roll him to the side keeping his head and neck immobile. If he is not breathing, administer mouth-to-mouth resuscitation. If the person is conscious, do your best to keep him calm and still. If he vomits, sit him up slightly and help him lean forward, unless you suspect a neck injury; in that case, keep head and neck immobile and roll him to the side. 

• If he has a seizure, keep his airway clear. 

• If there is swelling, apply an ice pack or cold pack. 

• If there is bleeding, apply a sterile dressing (bandage). 

• Do not attempt to cleanse the wound, which may aggravate bleeding and/or cause serious complications if the skull is fractured.

• Do not apply direct pressure to the wound if you suspect the skull is fractured. 

• Do not remove any object that is stuck in the wound. 

• So, all said and done, the best policy is to use a helmet when you are driving or riding a two-wheeler. Play safe because you only live once.