• a) Drop off in the patient acute headache pain (2 minutes, weekly for 20 weeks)
  
• b) Number of days without headache pain following infiltration
  

Gonyautoxin are phycotoxins, whose molecular mechanism of action is a reversible block of the voltage-gated sodium channels at neuronal level. They are axonal conduction blockers impeding nerve impulse propagation. In order to evaluate the clinical efficacy of Gonyautoxin 2/3 epimers in the treatment of patients diagnosed with chronic tensional-type headache, the patients were locally injected with placebo versus Gonyautoxin following a painful spots injection standarized protocol

Inclusion Criteria:

• Chronic tensional-type headache patients according to the International Headache Society criteria: patients with headache of a pressing or tightening quality with episodic frequency above 15 days a month
• Refractory to conventional treatments such as, orally administered analgesics, systemic muscular relaxant, corticoids and antidepressant like Amytriptiline
• Treated and controlled in the University Hospital Neurology Clinic over 2 years with duration of symptoms over 3 years

Exclusion Criteria:

• Pregnancy
• Use of headache prophylactic treatment a month prior to infiltration
• Myasthenic syndromes
• Muscular dystrophies
• Inflammatory myopathies
• Acute and chronic polineuropathies
• Use of psychotropic substances 24-hour before infiltration
• Anticoagulant treatment
• terminal illnesses (AIDS, cancer)
• drugs or alcohol abuse