It is normal to have migraine headaches from time to time. But some people have a migraine headache more days than other, that is the chronic migraine.
chronic migraine must occur 15 days per month, for three months and more. And chronic migraine headaches must not be a result of another condition.
Chronic migraine are classified by how long they last, some lasts more than five hours or less than five hours, the longer lasting migraine are more common and divided into four types Chronic migraine, Chronic tension migraine, new daily persistent migraine and hemicrania continua.

Chronic migraine
These chronic migraines comes without aura. To be sure you have chronic migraine, you must have migraine headaches, chronic tension type or both, and it have to last 15 days or more a month, for three months, and your migraine headaches have two of the following characteristics:

  • Migraine Cause a pulsating pain
  • Migraine Cause moderate to severe pain
  • Migraine that Are aggravated by routine physical activity
  • Migraine that Affect only one side of your head

And they cause one of the following:

  • Sensitivity to sound and light
  • Vomiting, nausea or both

Chronic tension type headache
These headaches evolve from episodic tension-type headaches. They may last hours or be constant.

Chronic tension-type migraine have two of the following characteristics:

  • Migraine Cause mild to moderate pain
  • Migraine Cause pain that feels pressing or tightening, but not pulsating
  • Migraine that Hurt on both sides of your head
  • Migraine that Aren’t aggravated by routine physical activity

And they cause one of the following:

  • Nausea
  • Sensitivity to sound or light

New daily persistent migraine
These migraine headache become constant in a few days of the moment after you have your first headache

New daily persistent migraine have two of the following characteristics:

  • Migraine Cause mild to moderate pain
  • Migraine that Hurt on both sides of your head
  • Migraine Cause pain that feels like pressing or tightening, but not pulsating
  • Migraine that aren’t aggravated by routine physical activity

And they cause one of the following:

  • Mild Nausea
  • Sensitivity to sound or light

Hemicrania continua migraine
These migraine headaches cause pain on one side of your head. They also:

  • Respond to the prescription pain reliever indomethacin
  • Cause moderate pain but with spikes of severe pain
  • May sometimes become severe with development of migraine- like symptoms
  • Are daily and continuous with no pain-free periods

hemicrania continua migraine headaches cause one of the following:

  • runny nose or Nasal congestion.
  • redness or tearing of the eye on the side which has migraine

Chronic migraine Causes:
The causes of chronic migraine aren’t well understood. They may happen if:
The part of your brain that suppresses pain signals isn’t working.
You develop a heightened response to pain signals.

Other frequent migraines may be caused by various underlying conditions, including:

  • Broblems with the blood vessels around the brain.
  • Infections
  • Intracellular pressure that’s either too low or too high
  • Brain injury
  • Brain tumor