For someone with a history of migraine headaches, the signs are familiar and unmistakable.

Scott Huler of Raleigh, age 50, who has had migraines since adolescence, describes "a neon flashing in my eyes, a small blot that eventually spreads to about 90 percent of my vision; I can still see but am unable to drive or read. Soon after, there's a piercing, almost electrical pain that to me is completely different from a regular headache."

But for others the distinction is not always so clear. There's a wide range of possible migraine symptoms, due to the complex activities occurring in the brain, says neurologist Heather Adkins, MD, who specializes in headache and face pain at the Duke Pain Clinic.

"A migraine is an event in the brain that actually starts well before the pain begins. A neuron in the brain's cerebral cortex becomes activated, and that activation spreads to other neurons -- it's almost like what happens in a seizure."

But while a seizure is a spreading wave of increased brain activity, a migraine is a wave of decreased brain activity -- that’s why early symptoms can include vision problems, difficulty  concentrating, or numbness or tingling in the extremities.

The pain of a migraine occurs when the trigeminal nerve is stimulated and releases substances that inflame and dilate the blood vessels around the meninges, which are pain-sensitive membranes encasing the brain.

Distinguishing Headache Types

So how do you know if you have a migraine? Migraine sufferers often report throbbing or pounding sensations, whereas tension headaches are more commonly described as a tightening or steady ache, often a band-like sensation around the head.

Tension headaches at their strongest may be hard to distinguish from migraines, but they don’t tend to have the additional symptoms associated with migraines, such as migraine aura that involves visual disturbances and tingling. Nausea and increased light and sound sensitivity, frequently reported by migraine sufferers, are uncommon for tension headaches -- which, by definition, cannot have more than one of these symptoms.

Also, physical activity does not typically increase tension headache pain as it does migraine pain.

Another strong indicator of migraine is having a family history of it. "Since so often there are multiple family members with migraines, we think the cause is primarily genetic," says Adkins.

There may be a hormonal component to migraines in women, she adds. "Men and women have the same rate of migraines until puberty; after that, women are at greater risk. Many women report migraines flaring up or worsening around the menstrual cycle or after pregnancy."

Treatment for Headache Pain

Whether it’s a tension headache or a migraine, treatment is available. "Treatment of migraine has advanced significantly in the last several years," notes Adkins, "so if you couldn't find adequate relief before, it's worth seeking help again; we have a lot of new options available, and more are on the horizon."

It's vital to seek immediate help for sudden, severe headache, which can be an early sign of stroke. Other warning signs include: numbness or weakness in the face, arm, or leg; confusion such as difficulty speaking or understanding; vision problems in one or both eyes; or trouble walking, dizziness, or loss of balance.

"For a thunderclap type of headache, go to the ER immediately," stresses Adkins. "And any time you have a headache that's different from usual -- if it's changed in pattern, in frequency, in intensity -- call your doctor."