Neurological Lyme disease, also known as neuroborreliosis, occurs when the bacterium Borrelia burgdorferi spreads to the nervous system. This condition can affect the brain, spinal cord, and peripheral nerves. It represents a more advanced stage of Lyme disease, typically developing in individuals whose initial infection was not treated promptly. Symptoms can be diverse, often mimicking other neurological conditions, making diagnosis complex.
How Lyme Disease Affects the Nervous System
The bacterium Borrelia burgdorferi is transmitted to humans through the bite of infected black-legged ticks. Once inside the body, these spirochetes can disseminate through the bloodstream, potentially reaching the nervous system. Borrelia burgdorferi can invade the central nervous system (CNS) by crossing the blood-brain barrier.
The blood-brain barrier is a protective layer that restricts the entry of harmful substances into the brain. While the exact mechanisms by which Borrelia burgdorferi crosses this barrier are still being investigated, it is known to trigger neuroinflammation once inside the nervous system. This inflammation can impact different areas, such as the membranes surrounding the brain and spinal cord (meningitis), the brain tissue itself (encephalitis), or the nerve roots.
Signs and Symptoms of Neurological Lyme Disease
Neurological Lyme disease can manifest with a wide array of symptoms, often appearing weeks to months after the initial tick bite. These symptoms can be variable and non-specific, depending on which part of the nervous system is affected. Common symptoms include severe headaches and neck stiffness, which can indicate inflammation of the membranes surrounding the brain and spinal cord, a condition known as meningitis.
Cranial nerve palsies are another frequent manifestation, particularly facial palsy, often referred to as Bell’s palsy. This involves weakness or paralysis on one or both sides of the face, making it difficult to close an eye, smile evenly, or control drooling. Other cranial nerves can also be affected, leading to symptoms like double vision, hearing loss, dizziness, or numbness and tingling in the face.
The peripheral nervous system can also be impacted, leading to nerve pain, numbness, or tingling sensations. This inflammation of the spinal nerve roots can result in sharp pain, muscle weakness, or even paralysis in affected limbs. Cognitive difficulties, often described as “brain fog,” are also reported, including problems with memory, concentration, information processing, and word retrieval. Less common but serious symptoms can include altered mental status, coordination problems, or inflammation of the brain (encephalitis) or spinal cord (myelitis).
Confirming a Diagnosis
Confirming a diagnosis of neurological Lyme disease involves a comprehensive approach, beginning with a thorough medical history that includes questions about potential tick exposure. A physical examination helps assess neurological function and identify any observable signs. Serological tests, such as enzyme-linked immunosorbent assay (ELISA) and Western blot, are performed on blood samples to detect antibodies to Borrelia burgdorferi. A positive ELISA result is followed by a Western blot to confirm the presence of specific antibodies.
For suspected neurological involvement, analysis of cerebrospinal fluid (CSF) obtained via a lumbar puncture, also known as a spinal tap, is performed. This test looks for inflammatory changes in the CSF, such as an elevated white blood cell count, increased protein levels, and the presence of Borrelia-specific antibodies produced within the central nervous system. A higher concentration of Borrelia antibodies in CSF compared to blood suggests the infection has reached the central nervous system. Neuroimaging, such as magnetic resonance imaging (MRI) of the brain or spinal cord, may also be used to rule out other conditions that can cause similar neurological symptoms or to identify specific areas of inflammation.
Treatment Approaches
The primary treatment for neurological Lyme disease involves antibiotic therapy to eradicate the Borrelia burgdorferi infection. The choice of antibiotic, route of administration, and duration of treatment depend on the severity and specific manifestations of the neurological involvement. For milder forms, such as facial palsy, oral antibiotics like doxycycline are prescribed for a course of 14 to 21 days. Amoxicillin may be used for children under eight years of age or pregnant individuals.
For more severe presentations, including meningitis or significant central nervous system involvement, intravenous antibiotics are administered. Ceftriaxone is a preferred intravenous antibiotic, given its ability to effectively penetrate the blood-brain barrier. Other intravenous options include cefotaxime or penicillin G. The duration of intravenous treatment ranges from 14 to 28 days.
The goal of antibiotic treatment is to eliminate the bacteria and alleviate symptoms, with most individuals responding well and experiencing a full recovery. However, some individuals may experience persistent symptoms even after successful antibiotic therapy, a condition sometimes referred to as post-treatment Lyme disease syndrome. These lingering symptoms do not necessarily indicate ongoing active infection and may require individualized management to address specific concerns.