Friday, January 22, 1999 Published at 00:08 GMT
Headache or impotence? You pick
Over-the-counter painkillers are the first treatment
A study could lead to tension headaches becoming a thing of the past, but impotence could be a possible side-effect of any treatment.
Any potential pill would block the production of a chemical essential for making tissue erect.
Tension-type headaches account for nearly 90% of all headaches, but they are difficult to treat.
There is no consensus on what the best treatment is, but commonly recommended approaches include over the counter painkillers, physical therapy and in some cases antidepressants.
Their causes are also unknown - although stress and depression have been implicated.
Finding out what is behind them brings doctors one step closer to a cure.
There are two types of tension, or stress, headache. Episodic tension headaches can occur infrequently, such as one brought on by an individual stressful event.
Both types are characterised by a band of pain in the temporal region of the head.
Now scientists have found that a substance that inhibits the production of nitric oxide can relieve the pain of chronic tension-type headaches.
The research was conducted by Dr Messoud Ashina and colleagues from Glostrup Hospital and the University of Copenhagen, Denmark.
They published their findings in the Lancet medical journal on Friday.
They used the substance monomethyl-L-arginine (L-NMMA). This blocks the enzyme nitric oxide synthase (NOS).
The enzyme would normally help make nitric oxide, a chemical that has been implicated in many processes in the body, including regulation of blood pressure, defence against infection, function of blood platelets, and transmission of some types of nerve impulses.
The reduction in the chemical helped relieve the headache, but it nitric oxide has another function - it is central to the production of erect tissue.
Dr Nigel Benjamin, a clinical pharmacologist at St Bartholomew's Hospital in London, wrote a commentary on the research.
He said the research showed great potential for further advance in the field of pain relief, and that "there is also preliminary evidence that L-NMMA is effective in the treatment of migraine".
However he added: "The trouble is that, although the development of a safe, selective neuronal NOS inhibitor that is active when taken orally and that also enters the brain and spinal cord might mean the availability of an agent that can relieve pain such as chronic tension-type headache, impotence would be an expected side-effect."
The researchers in Denmark studied 16 patients with chronic tension-type headache.
Each patient had one injection of L-NMMA and another of inactive placebo, on two separate days when they had a typical headache.
Before treatment, then at 30 minutes, 60 minutes, and 120 minutes after the start of treatment, the patient indicated how severe the headache was.
For this they used a 100 mm line where one end line is no pain and the other is the worst pain imaginable.
The average pain score was lower 120 minutes after treatment started than before with both treatments.
However, the change in average score was significantly larger. With the active chemical the pain score fell from 49 to 33.
With the placebo it only fell from 44 to 40.