Rebound or Medication Induced Headaches
The patient who present with chronic daily headaches is often a challenge for the clinician to both diagnose and treat. Their headaches may be associated with the daily use of prescription and/or over the counter analgesics. The constant use of such medications frequently provide partial temporary relief, however, they often serve to compound the problem. The chronic use of analgesics can result in the development of a second headache syndrome called medication induced headache (MIH).
Definition
Medication induced headache (MIH) can be defined as a headache syndrome in which daily or near-daily ingestion of symptomatic therapies partially relieves the headache in the short term but enhances headache frequency (and may increase severity) in the long term.
Pathophysiology
The pathophysiology of MIH is not completely understood, however all drugs found to be associated with MIH appear to share a common site of action at the serotonin (5-HT) receptors. These drugs include ASA, acetaminophen, codeine and it’s derivatives, ergotamine and it’s derivatives and propoxyphene. Stimulation of the 5-HT1 receptor subclass leads to three principal outcomes: vasoconstriction, inhibition of neuropeptide-induced inflammation (with a reduction of pain), and an increase in the sensory afferent firing threshold. Discontinuation of receptor stimulation (by drug withdrawal) results in a heightening of pain perception. There is no laboratory evidence that chronic use of analgesics results in a down regulation of serotonergic receptors, however Hering and Steiner recently reported that whole blood concentrations of serotonin values were depressed in patients with MIH. Interestingly it was also noted that serotonin values returned to normal, and that headaches abated, when analgesics were discontinued.
Clinical Features
MIH can exhibit clinical features of either tension or migraine and should be suspected under the following conditions:
- Daily or near daily frequency of headache
- Daily or near daily ingestion of analgesic medications for over three months
- Pain that varies in severity and location, medications give only partial relief
- Aggravation of headache by physical activity or mental effort.
- Associated symptoms of nausealessness, forgetfulness and fatigue
- Headache persistent upon awakening and unremitting until the habitual dose of medication is consumed
Diagnosis
The diagnosis of medication induced headache is based solely on history and a normal physical examination. Radiological investigations should be avoided unless the history or physical exam is suggestive of a secondary headache syndrome. There are no specific physical findings or abnormalities on laboratory or other diagnostic tests to aid in the diagnosis of MIH.
Treatment
The treatment of MIH is a challenge to both physicians and patients. Both parties must understand that withdrawing from the chronic use of analgesics may not mean freedom from headaches. It means freedom from a certain type of headache, MIH, and freedom from drug dependency. Many will continue to suffer from the primary headache that prompted the overuse in the first place.
A multidisciplinary approach is best suited for the treatment of MIH. Patients should be encouraged to keep a headache diary to track headache characteristics including triggers, headache type, medication consumption and effectiveness. The offending medications should be withdrawn abruptly for straight analgesic, and gradually, but on a fixed timetable, for agents such as barbiturates where withdrawal may carry a risk of seizures.
Those patients that suffer from withdrawal symptoms may benefit from the use of clonidine during the withdrawal period. For the symptomatic treatment of mild/moderate headaches, patients should be encouraged to use cold compresses rest and relaxation techniques. For severe migraine headaches patients can use 5-HT agonists such as sumatriptin or DHE, and NSAIDS.
For headaches that are not clearly migraines NSAIDS such as naproxen sodium are often useful. Treatment must also be tailored to the original primary headache syndrome. It should include the use of prophylactic headache medications such as beta blockers or tricyclic antidepressants were indicated. Patients that have a cervical myofascial component to their primary headache syndrome may benefit from physical rehabilitation, and in the most resistant cases myofascial trigger point injections and occipital nerve blocks. Patients should be reminded that it may take up to 8 weeks for the effect of prophylactic medications to begin working. They should also be warned that their headaches may initially become more severe, and it may take up to 12 weeks of analgesic abstinence before MIHs begin to dissipate. Frequent regular follow up and physician reassurance are crucial to the treatment of MIH.