Botulinum toxin in tension-type headache

Abstract

Tension-type headache (TTH) is by far the most common form of primary cephalaIgia with a lifetime prevalence between 30 and 78 %. From the new IHS classification, we distinguish between the following subtypes: 1. Infrequent episodic tension-type headache 1.1 Infrequent episodic tension-type headache associated with pericranial tenderness 1.2 Infrequent episodic tension-type headache not associated with pericranial tenderness 2. Frequent episodic tension-type headache 2.1 Frequent episodic tension-type headache associated with pericranial tenderness 2.2 Frequent episodic tension-type headache not associated with pericranial tenderness 3. Chronic tension-type headache 3.1 Chronic tension-type headache associated with pericranial tenderness 3.2 Chronic tension-type headache not associated with pericranial tenderness 4. Probable tension-type headache We speak of chronic type headache when pain has been present for more than 50 % of the time for at least 3 months (IHS classification). Approximately 3 % of the European population suffers from chronic tension type headache.Etiology and pathogenesis of TTH is still not definitely clear, especially concerning the question whether TTH is primarily triggered centrally or peripherally. A manifold etiology is generally presumed. According to the new IHS classification, another distinctive feature in TTH is present or absent association with pericranial sensitivity to pain -the frequency of tension headaches apart. Manual palpation, pressure-controlled palpation of the pericranial muscles in particular, has in the past been a helpful distinguishing feature to differentiate between these subtypes of TTH. Pericranial tenderness of certain regions, frequently associated with increased muscular tenderness, may be rated as a peripheral mechanism in the form of activating peripheral nociceptors. Conversion to chronic TTH is enhanced via secondary central sensitization and/or impaired supraspinal modulation of incoming nociceptive stimuli of myofascial tissues and ensuing myalgia. Chronic TTH is thus characterized by central changes (decrease) of the pain threshold and central misinterpretation to a greater extent than the episodic type headache. It would seem that it just takes minor myofascial stimuli to trigger a headache. Treatment of TTHPrior to any treatment it is particularly important to define realistic objectives and to correct unrealistic goals. Whatever the treatment it should be preceded by information and counseling. Acute therapy with analgesics can suffice in episodic TTH. A nondrug prevention and/or prophylaxis is, however, indicated in cases of frequent attacks and above all in chronic TTH. This includes a clearly structured day, endurance sports, exercises, relaxation techniques and topical applicationsincluding elimination of etiologic factors. Specific treatment of mental disorders is called for if present.Tricyclic antidepressants are first choice in drug treatment. Valproic acid and tizanidine need be discussed in view of the controversy about them. The suc-