The treatment for Lyme disease is fairly straightforward — except when it isn't.

Spread by the bite of infected ticks, Lyme disease is usually treated with a brief course of antibiotics. Given the standard treatment within a few weeks of infection, most Lyme disease sufferers will recover completely.

For an unfortunate few, however, the initial symptoms of Lyme disease are followed by lingering joint pain, long-term neurological problems (neuroborreliosis) and other chronic conditions sometimes lumped together as "post-Lyme syndrome."

Doctors have very little understanding of what these conditions are or how they work. Even worse, there are no established treatments. Based on their effectiveness against early-stage Lyme disease, many doctors try to fight the persistent form of the disease with antibiotics as well.

Now, however, a new guideline issued by the American Academy of Neurology addresses this issue. The AAN finds that conventionally recommended courses of antibiotics are highly effective for treating nervous system Lyme disease, but that there is no compelling evidence that prolonged treatment with antibiotics has any benefit in treating longer-term symptoms.

The guideline was published May 23, 2007, in the online edition of Neurology, the scientific journal of the American Academy of Neurology.

Lyme disease affects the nervous system in 10 to 15 percent of its victims.

"While other guidelines exist to help diagnose and treat general Lyme disease, there continues to be considerable controversy and uncertainty about the best approach to treating neuroborreliosis, in which Lyme disease involves the nervous system," said lead guideline author John J. Halperin, MD, with Atlantic Health in Summit, NJ, and Fellow of the American Academy of Neurology.

To develop the guideline, the authors analyzed all available scientific studies, finding that using antibiotics for two to four weeks is highly effective for treating neuroborreliosis. Lyme disease responds well to the intravenous antibiotics penicillin, ceftriaxone, cefotaxime, and oral doxycycline, and these antibiotics are probably safe and effective when taken for 14 to 28 days by children and adults.

However, the guideline states that longer-term use of antibiotics does not improve outcomes in people with chronic symptoms who have already had the standard treatment. Further treatment does not improve overall health quality of life, memory or depression. This is important becaise long-term antibiotic use has a down side — it is can cause diarrhea, blood stream infections and blood clots.

"While it is clear from all available scientific studies that long-term use of antibiotics doesn't help to treat chronic symptoms that persist after treatment for Lyme disease, the symptom complex will remain problematic until we can better understand the cause of these symptoms and find appropriate treatments," said Halperin.