Brain Scans for Lyme Disease

Lyme disease is an infection that's transmitted to humans through the bite of a black-legged tick. The Centers for Disease Control and Prevention says more than 20,000 cases of Lyme disease were reported in 2005. However, since many cases are never diagnosed or reported, the actual number is probably much higher. In the northeastern U.S., peak season for tick bites is April through September.

The first sign of infection after a tick bite is a red, circular rash, which about 70 to 80 percent of people develop the rash, usually within 3 to 30 days of the tick bite. The rash may expand and develop a clear spot in the middle (leading to the formation of a "bull's eye" on the skin). Patients may also experience fatigue, chills, weakness, fever, headache, muscle pain or joint pain.

In the early stages, Lyme disease can often be cured with oral antibiotics. If the infection isn't treated, it can spread throughout the body. Patients may develop weakness or numbness on one side of the face (Bell's palsy), severe headaches, neck stiffness, abnormal heart rhythms, dizziness and joint pain. Oral or intravenous antibiotics may be used. However, many of the symptoms eventually go away on their own.

Several months to years later, about 60 percent of patients with untreated infections may develop intermittent symptoms of arthritis, causing severe joint pain and swelling. The knee is the most commonly affected joint. Five percent of patients develop neurological signs, like numbness and tingling in the hands and feet, shooting pains, and problems with short-term memory and concentration.

Brian Fallon, M.D., a Psychiatrist at the Lyme & Tick-borne Diseases Research Center, Columbia University Medical Center, says about 60 percent of patients with neurological symptoms of Lyme disease get better with intravenous antibiotics. Another 20 percent of patients will initially respond to the treatment, then relapse (develop symptoms again). For the other 20 percent, intravenous antibiotics don't seem to help at all.

Symptoms of chronic Lyme disease can be severely debilitating and may include periods of fatigue, sudden mood swings, changes in personality, depression, headaches and short-term memory problems. When patients continue to show signs of a problem, doctors may be uncertain how to proceed with treatment. There currently is no test to accurately diagnose chronic Lyme disease. Some doctors may continue treating the patient with antibiotics, while other physicians may discontinue treatment for fear of promoting antibiotic resistance.

Fallon is using imaging scans to look at the brains of patients with persistent, or chronic, neurological signs of Lyme disease. MRI scans look at the structure of the brain and may detect spotty areas of inflammation. The scans may be useful to rule out MS, which causes large areas of inflammation in the brain. PET scans and SPECT scans look at the function of the brain.

Many different problems can cause changes in how the brain functions, so doctors may still need to rule out other possible conditions. However, Fallon hopes to eventually detect brain patterns that are characteristic of Lyme disease. Eventually, the information could be used to develop more accurate diagnostic tests for chronic Lyme disease.