Lyme Disease

Overview

Lyme disease is a tick-born illness caused by the bacteria Borrelia burgdorferi. Symptoms include skin lesions, neurological signs, cardiac symptoms, and arthritis. This article will focus on the neurological aspects of Lyme disease. Lyme disease is typically successfully treated with antibiotics; however, a minority of individuals develop chronic Lyme disease. The efficacy of prolonged antibiotics regimen is low for these individuals. There are currently no clinical trials to evaluate other treatment modalities.

Symptoms

Initially, an individual infected with Lyme may have a characteristic skin lesion (an area of redness called erythema chronicum migrans), malaise, fatigue, fever, headache, stiff neck, or muscle or joint pain. As the disease progresses, some people begin to experience neurologic or cardiac symptoms. Finally, these individuals may develop arthritis. In terms of neurological symptoms, infected individuals may suffer from meningitis (infection of the membrane covering the brain; symptoms include fluctuating headache, nausea, vomiting, light sensitivity, or pain with eye motion), encephalitis (infection of brain tissues; symptoms include sleep disturbances, concentration difficulties, irritability, emotional distress), and inflammation of spinal or cranial nerves (sensory or motor symptoms, such as facial weakness and tingling or painful sensations of the extremities) (1). Chronic Lyme disease may be accompanied by persistent cognitive symptoms, such as difficulties with attention, processing speed, executive functions (higher-order cognitive abilities such as planning, organizing, abstract reasoning, and rapid word generation), and fine motor skills (2).

Prevalence

The incidence of Lyme disease is higher during the summer (1). According to the Centers for Disease Control and Prevention (CDC), approximately 30,000 cases of Lyme disease are reported to the CDC every year. However, studies conducted by the CDC have put the estimates closer to 288,000 to 329,000 cases per year (3).

Course and Treatments

Mean duration of neurological symptoms is 30 weeks (1). Lyme disease is successfully treated with antibiotics in most cases. Even if untreated, symptoms usually resolve within months (4). Those with late manifestations may respond more slowly to therapy and take longer to recover. Some may have incomplete resolution of symptoms due to irreversible damage, such as with facial weakness (5). A minority of infected individuals suffer from chronic neurological dysfunction, after their initial symptoms already resolved. These symptoms commonly begin 16 months (median) after infection onset for peripheral nervous system (nerves outside of the brain and spinal cord) involvement, and 26 months (median) after infection onset for central nervous system (brain and spinal cord) dysfunction. Some people may not begin to develop chronic neurological symptoms until 10 or more years after initial infection (4). The exact mechanism of chronic Lyme disease is unknown, but possible pathways include persistent infection with the bacteria, other tick-borne infections, postinfective fatigue syndrome, autoimmune mechanisms, and other concurrent conditions. Four randomized control trials have demonstrated that prolonged antibiotics regimens do not provide sustained benefit for chronic Lyme disease. There are currently no clinical trials evaluating other treatment modalities for chronic Lyme disease (5, 6).

By Michelle Chen

References

1. Pachner, A, & Steere, A (1985). The triad of neurologic manifestations of Lyme disease Meningitis, cranial neuritis, and radiculoneuritis. Neurology, 35(1), 47-47.
2. Rissenberg, M, & Chambers, S (1998). Distinct pattern of cognitive impairment noted in study of Lyme patients. Lyme Times, 20, 29-32.
3. Centers for Disease Control and Prevention. How many people get Lyme disease?. Retrieved from https://www.cdc.gov/lyme/stats/humancases.html.
4. Logigian, E, Kaplan, R, & Steere, A (1990). Chronic neurologic manifestations of Lyme disease. New England Journal of Medicine, 323(21), 1438-1444.
5. Marques, A (2008). Chronic Lyme disease: a review. Infectious disease clinics of North America, 22(2), 341-360.
6. Kaplan, R, Trevino, R, Johnson, G, Levy, L, Dornbush, R, Hu, L, & Klempner, M (2003). Cognitive function in post-treatment Lyme disease: Do additional antibiotics help?. Neurology, 60(12), 1916-1922.