By: Robert S.C. Amaral

Lyme Neuroborreliosis (LNB) is the neurological manifestation of systemic infection with Lyme disease, caused by tick-borne spirochete Borrelia burgdorferi sensu lato[1] . Its passage through the Blood-Brain-Barrier results in Central Nervous System (CNS) infection, causing widespread neurological symptoms. Early effects of CNS infection include headaches, encephalomyelitis and facial paralysis. In later stages, severe neuropsychological issues such as sensory loss and schizophrenia-like psychosis may develop[2] . The observed variability in symptoms has been attributed to changes in brain structure, blood flow and atrophy due to bacterial inflammation and toxicity[1]. Despite these findings, the true molecular and neurophysiological correlates behind symptoms remain largely elusive. If left untreated, LNB progression results in irreversible brain damage leading to severe dementia and death. Although variability in LNB symptomology may present problems for diagnosis, understanding it’s specific effects on the brain may aid in further interpretation of disorders commonly mistaken and linked to LNB (e.g. Alzheimer’s Disease, Multiple Sclerosis, Bell’s Palsy). With bacterial strains present across the world, including Europe, North America and Asia, LNB cases have been steadily increasing over the years, and death from improper diagnosis has become more frequent.
1. Bacterial Profile: Borrelia
2. Epidemiology
3. Transmission
4. Stages, Signs and Symptoms
5. Specific Neurological-Bacterial Effects
6. Diagnosis
7. Treatment

1. Bacterial Profile: Borrelia

Borrelia burgdorferi spirochete.
The causative agent of Lyme Neuroborreliosis is a spirochete bacterium of the family
borrielia. Of the 36 known strains, only 12 are thought to cause Lyme disease and it’s later CNS infection, Lyme Neuroborreliosis[3] . Phylogenetic analysis has resulted in the classification of Lyme-causing bacteria to be collectively known as Borrelia burgdorferi sense lato[3]. The three major genospecies most pathogenic to humans include: Borrelia burgdorferi, Borrelia afzelii, and Borrelia garinii. These spirochetes have long, helically coiled cells with flagella located exclusively in their periplasmic space[4] . These flagella allow for it’s unique ability for spiral-like movement through viscous extracellular medium and host cell membranes. Their genomes are thought to be among the most complex out of all known bacteria, with a single 1Mb chromosome and an assortment of linear/circular plasmids totaling over 600kb[5] . Housekeeping genes are present in the chromosome, whereas plasmids which vary in both number and organization encode for surface lipoproteins. Borrelia burgdorferi sensu lato are general auxotrophs, and therefore are unable to synthesize their own fatty acids, amino acids, or nucleotides, relying on nutrient sources from its host. A key feature of these spirochetes is that they do not seem to require iron for their survival or maintenance; a feature which is uncharacteristic of most infectious bacteria[6] . Moreover, they do not conserve genomic machinery for the metabolic use of oxygen (e.g. tricarboxylic acid cycle, oxidative phosphorylation) and therefore rely on anaerobic energy via fermentation of sugars to lactic acid using the Embden-Meyerhof pathway[7] . It is important to note that the Borrelia burgdorferi sensu lato do not encode any known toxins, nor machinery for their production, rather it is the resulting immune response that leads to diffuse damage in the mammalian system[3].
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2. Epidemiology

Lyme Disease risk map of the USA.
Lyme Disease (LD) is the most frequently reported tick-related infection in the western hemisphere with most cases being present throughout Canada and the USA[8] . Borrelia burgdorferiinfected ticks are present globally, but seem to be endemic to specific regions throughout Canada and USA. Incidence rates of LD in Canada have slowly risen over recent years, with new cases being present further inland, possibly due to the travel of spirochete-carrying ticks via birds from endemic costal (British Columbia, Nova Scotia) and southern-central regions (Manitoba and Ontario). These provinces maintain high tick numbers and subsequently greater relative risks of LD infection. The current incidence rate of LD in Canada remains unknown since it has only recently (in 2010) become a reportable disease. Despite this, some provinces have collected LD statistics over the years. Specifically, epidemiological studies have demonstrated 172 confirmed and reported cases of LD during a ten-year span from 1994 to 2004, with numbers of endemic-related cases in Ontario reported to be 5-10 per year[9] . These quantitative reports are subject to error due to a lack in government-enforced case reportings and diagnosis; current incidence estimates are therefore thought to be as high as 2000 to 20,000 per year[9]. Confirmed cases of LD in the USA are over 200,000, resulting in an incidence rate of 9.7 cases per 100,000 people[10] . The majority of reported cases originate from Atlantic costal states such as Connecticut, Maine, New Jersey, etc.
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Infected tick population in Canada.
Borrelia afzelii and Borrelia garinii are the genospecies most frequently encountered in continental Europe, although co-infections with Borrelia burgdorferihave been documented[10]. Incidence of LD in South Western Europe (e.g. Italy, Portugal, Spain), are present at lower rates. Scandinavian countries have also presented cases of LD, with increased numbers seen in southern Sweden[11] . Here incidence rates are about 69 per 100,000 individuals, a high incidence rate given that Sweden’s population is approximately 9 million. Lyme in other countries include Slovenia (155 cases of LD per 100, 000), as well as the Netherlands[12] [13] . LD-causing strains and cases have also been located to the UK, Africa, as well as Asia (including Japan, Nepal, Thailand, Mongolia and Russia)[14] .
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Based on geographical location, season, location of tick bite, and strain, development of the LD CNS infection (LNB) may vary. It is estimated that 10-15% of all individuals infected with LD will proceed to develop LNB[15] . Few epidemiological studies have sought to determine infection rates and incidences of LNB, possibly due to issues in its diagnosis and difficulty in data access/collection. Despite this, the Netherlands have demonstrated 3.6 cases of LNB per 1,000,000 inhabitants, and Germany with 5.8 cases per 100,000 children[13],[16] . Naturally, equivalently higher numbers are expected in North American countries [9].

The aforementioned statistical quantifications of LD and LNB are generally taken to be lower then actual accounts due to a lack in disease report and accurate diagnosis[9]. Early stages of LD often go unnoticed, and later stages of LNB are often misdiagnosed. Progression through the body is also highly variable. These factors all contribute to decreases from true rates of incidence; the reality of LD and LNB infection is much higher.
  • The United States are one of the only countries to publish confirmed annual and probable cases of Lyme Disease occurrences by year, state, age, sex, month and symptom. For More information visit Centers for Disease Control and Prevention (CDC) website:

3. Transmission

Transmission of LD occurs via ticks infected with Borrelia burgdorferi sensu lato. Multiple species of ticks can become infected with either strains of the spirochete, but principal tick species known to harbor bacterial strains include Ixodes scapularis and Ixodes pacificus (blacklegged ticks) in North America, Ixodes ricinus in Europe and Ixodes persulcatus in Asia[17] . Despite morphological differences, all ticks have common physiological adaptations used for feeding practices. Ticks anchor to a host using a harpoon-like hypostome that then allows them to burrow a hole through the skin epidermis. Being a hematophage, they then feed off the animal’s blood[3]. During feeding, saliva infected with the bacterial spirochete can then be transmitted to a host[18] .

Borrelia-harboring tick lifecycle. Original image reproduced from (3).
Ticks first hatch from female eggs laid in soil, and are born unaffected by the
Borrelia spirochete[3]. Larvae then infect a first host, which are often primary reservoirs for the bacterial spirochete. These animals have previously been exposed to one, or multiple strains, of the Borrelia spirochete and asymptomatically maintain levels of the pathogen in their blood. Primary reservoirs include small vertebrae mammals such as mice, voles, squirrels, etc. Birds and larger mammals such as deer may also serve to harbor pathogens. After their first feeding, larvae consequently become infected due to spirochete presence in their blood meal. After undergoing a transition to a nymph stage, a second meal takes place. It is at this stage where human infection is most common. Feeding results in tick saliva infected with the bacterial spirochete to be transmitted[18]. Ticks typically stay on their host for long periods of time, and this transmission process was first shown to take over 48 hours[19] . However recent evidence has demonstrated transmission of Borrelia burgdorferi to be possible under 24hrs, as documented in three separate cases[20] . After this transmissive stage, the nymph molts to an adult and then feeds/breeds off larger mammals like deer[3].

Despite tick bites being the main method of transmission, controversy over other modes of infection are present in literature. Debate still exists as to the potential of LD being a sexually transmitted disease. Patients infected with LNB consequently maintain levels of spirochetes throughout their blood and other bodily fluids, including semen[21] . PCR analysis of both animal and human semen has shown to hold relatively high amounts of Borrelia spirochetes [21],[22] . Despite this, cases of LD transmission through sexual intercourse have not yet been reported. Studies where infected hamsters were allowed to mate with uninfected sexual mates did not show successful transmission[23] . Although this experimental result may be convincing, definitively ruling out sexual transmission in humans is unreasonable.

A similar issue has also surfaced with respect to presence of bacterial spirochetes in female breast milk[24] . Cases of transmission from mother to child via infected milk have not been causally documented. However, transmission of pathogens from mother to fetus during pregnancy seems to be possible, with few but confirmed cases. Once again, rodent models of congenital infection are not supported experimentally[23]. Moreover infection of the fetus with Borrelia burgdorferihas been associated with abnormal pregnancies, stillbirths and complications and it is thus thought to act as a teratogen[25] . A causative link remains to be revealed.

Finally, since patients infected with LNB maintain decent levels of the bacteria in their blood, it is theoretically possible for transmission to occur via a blood transfusion [10],[26] . Documented cases have yet to occur[26].

4. Stages, Signs and Symptoms

Infection of humans with Borrelia burgdorferi sensu lato result in disease progression similar to that of related spirochete, syphilis[27] . Infection results in three stages of the disease: an early acute stage with fever-like symptoms, an early disseminated stage where infection spreads, and a later persistent stage where untreated disseminated stages result in severe neurological consequences. Symptoms throughout the different phases are highly variable, predominantly due to the unpredictable and diffuse spread of bacteria to various locations throughout the body[3]. Peripheral infection with one of the Borrelia strains is defined as Lyme disease. After crossing the blood brain barrier (BBB), along with the advent of neurological symptoms, the disease is classified as Lyme Neuroborreliosis[27]. Despite a plethora of symptoms, asymptomatic infections also exist and are extremely rare with incidences being more common in Europe[28] .

4.1 Early Localized Stage
Erythema migrans skin irritation.
The most common symptom following transmission is the presence of a skin irritation similar to a bulls-eye pattern. This characteristic rash is called erythema migrans and presents as a darker red circle bordered by a ring slightly lighter in colour. Only approximately 80% of individuals with confirmed cases of LD/LNB initially display this rash[27]. It most often appears surrounding the area of the tick bite, although, it may appear in areas adjacent to, or far from the bite[29] ,[30] . Erythema migrans may present itself 3-30 days post-transmission, and is accompanied by flu-like symptoms of fever, headache, migraines, myalgia (muscle aches),
lymphadenopathy (swollen lymph nodes), arthralgia (joint pain) and general malaise [27], [30]. During this acute stage, bacteria initially cause an immune reaction, however, their ability to hide in cells surrounding the bite allows for them to escape destruction[3].

4.2 Early Disseminated Stage
Weeks after local infection, Borrelia spirochetes pass into the bloodstream and subsequently travel to different areas of the body[30]. Efficient delivery of pathogens via blood enable random and sporadic presence throughout various organs including the liver, lungs, stomach, intestines, spleen and the uterus[31] . Here, spirochetes replicate in cells using host cellular components whilst parasiting nutrients from the host[3]. They also spread to muscles, joints and tendons where arthritic pains, as well as muscle aches and fatigue are exhibited[30], [31]. The heart may also become infected in a condition known as Cardiac Lyme borreliosis, causing palpitations resulting in dizziness spells. The peripheral nervous system is also affected and symptoms like tingling, muscle twitching, numbness and pain are evident[32] .

In some cases, Borrelia burgdorferi sensu lato strains cross the blood brain barrier and enter the Central Nervous System (Neuroborreliosis). Infection within the brain and spinal cord produce a variety of symptoms ranging in severity. Most commonly observed is the presence of facial palsy (loss of muscle tone on one side of the face). This may stem from both inflammatory destruction of facial nerve dorsal root ganglion cells or from CNS lesions to the corticubulbar tract and/or facial motor nucleus[27]. Although the most common nerve affected is cranial nerve 7, other nerves include cranial nerves 4, 5, 6 and 8. Additional symptoms include tremors, inflammatory meningitis and radiculopathy (due to spinal cord infection) resulting in pain, numbness and weakness[33] . Encephalitis and myelitis may also occur along with the aforementioned symptoms[27], [30]. Despite pathogenesis of CNS infection and molecular processes associated with penetration through the BBB remaining largely elusive, diffuse tissue damage is thought to be the consequence of severe host inflammatory reactions within the CNS.

4.3 Late Persistent & Chronic Stages
Delayed or untreated cases of early LNB past the disseminated stage result in increased number and severity of neurological deficits as CNS inflammation and tissue damage escalate[27]. Here extreme symptoms include a multitude of cognitive deficits including problems with attentional abilities, memory performance, bouts of confusion, as well as issues in concentration, judgment and decision making. Motor regions of the brain are also severely affected and may result in permanent paraplegia (or trouble moving limbs during walking), involuntary muscle movements, and reflex changes[34] ,[35] . Severe sensory impairments include the loss of hearing, touch and optic neuritis resulting in complete or partial loss of vision [35] ,[36] . Emotional irregularities as well as psychological symptoms of delusions, depersonalization, panic attacks and schizophrenia-like symptoms have been documented[2], [30], [33],[37] . The unpredictability and irregularity associated with LNB progression through the CNS may serve to explain the variance in neurological systems affected.

The chronic stage of LD describes patients who maintain a chronic infection of the Borrelia bacteria despite treatment. Here, post-treatment symptoms range from the spectra of aforementioned neurologic and peripheral manifestations of LD and/or LNB[30].

5. Specific Neurological-Bacterial Effects

The above-mentioned neurological symptoms of LNB are the consequence of host immune system reactions raised to the spirochetes, which result in inflammation and destruction of host material. Since LNB is still a relatively new disease, its molecular pathogenesis and effect on the body remains largely elusive. Despite this, recent histological and molecular studies along with imaging techniques have somewhat characterized the specific bacterial effects of Borrelia burgdorferi sensu lato on the mammalian CNS.

5.1 Histopathologyryryry.pngIn some cases, patients are subject to biopsies of nervous tissue for use in histological analysis. These analyses allow for direct visualization of spirochetes (although not reliable for diagnosis) and may give clues as to the physical processes occurring in tissues[30]. Histology preformed on LNB tissues show marked characteristics of inflammation[38] . In the case of a peripheral nerve biopsy (of LNB patient) perineuritis (inflammation of the perineurium) was visible. This study concluded the inflammation to be a direct result of infection following positive diagnosis for LNB. Moreover other results display nerve damage, cell apoptosis, and lesions in biopsied material[39] . The direct molecular events causing these effects need to be addressed.

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5.2 Molecular EffectsThe problem exists of directly observing molecular interactions within human hosts at the single cell level[40] . Therefore, appropriate use of animal models and in vitro experiments are necessary for LNB study.

The primary issue in LNB study concerns the molecular mechanisms behind spirochete translocation into the CNS through the BBB. To determine the process behind translocation, one study involved the engineering of a fluorescent strain of Borrelia spirochete which was then infected into mice[41] . This process allowed the spirochete to be viewed in mice via intravital microscopy. It was found that initiation of tethering and passage from the blood to other tissues (including nervous tissue) is mediated by the presence of Fn and GAGs on host cells, as well as the interacting spirochete protein BBK32. In addition, recent evidence has demonstrated that the presence of Borrelia proteins: CD40, BMECs and OspA (outer surface protein), are both significant and necessary in the tethering of spirochetes to an endothelium (study done in vitro).

It is thought that astrocytes facilitate the crossing of spirochetes into the CNS since they are most likely to be the first cell to be infected after the endothelial. This is due to the cell projections sent (astrocytic feet or glia limitans) to the capillary junction[42] . Abundances of glial fibrillary acidic protein in the CSF of LNB patients may indicate astrogliosis (astrocyte proliferation and apoptosis). Lipoproteins present on the bacterial surface such as lapidated outer surface protein A (L-OpsA), can directly result in astrogliosis of glia/astrocytes in rhesus monkey models of LNB. This may demonstrate that induced destruction and apoptosis of astrocytes is indirectly caused by surface proteins. The death of astrocytes therefore contributes to LNB pathogenesis and may lead to decreased delivery of nutrients and/or management of extracellular conditions (i.e. increased waste and toxins). Moreover, destruction of astrocytes may secrete factors that in turn damage other nearby cells. Other studies (using mouse models) have demonstrated the potential of another spirochete protein, OpsC, in inducing the release of nitric oxide (NO) from microglia in a dose-dependent manner[43] . Upon histological and immunohistochemical analysis, this process was seen to result in axonal damage after long term exposure. This demonstrates the potential for these proteins to indirectly mediate CNS tissue damage consequently affecting brain function.

As stated, Borrelia burgdorferi sensu lato do not release neurotoxins. It is the host immune system which causes inflammation and death of tissue[30]. Evidence for this includes the fact that excessive release of interleukin-6 (IL-6) and cytokines in response to the spirochete contribute to the toxicity necessary to kill neurons[42]. In addition, the dose-dependent increase of NO seen above has the potential to act as a neurotoxin and leads to neuronal death after excessive production.

Despite these data, the molecular mechanisms behind spirochete’s effects during LNB still remain largely elusive.

5.3 Evidence From ImagingNaturally, molecular mediating inflammation, astrocytic apoptosis and neuronal death will ultimately have an impact on brain structure and function. Imaging techniques allow for the structural examination of the brain. Functional imaging takes this a step further with the capability of probing for abnormal brain function.

  • MRI
    MRI use on LNB patients has demonstrated many abnormal pathologies associated with the presence of characteristic neurological symptoms. MRI scans have verified the presence of perivascular, and vasculitic lymphocytic inflammations[44] . Moreover diffuse and localized lesions, as well as demyelination has also been documented. DTI MRIs have also managed to show lesions in various CNS white matter tracts of LNB patients[45] . MRI scans have also been used to show changing vessel wall structure, strokes and ischemic lesions[46] . Frequently seen are brainstem lesions, and in one child case, MRI linked an abnormal mass growing out from the brainstem to LNB[27].

    Single-Photon Emission Computed Tomography (SPECT) is another technique used to view the brain. Here, it has been used to functionally test brain blood flow and metabolism. SPECT scans have been able to show issues in blood circulation through the LNB brain with abnormal metabolism occurring in frontal regions, and on either hemispheres as well as localized areas (e.g. in one study blood flow was decreased to only the Basal Ganglia)[27][47] .

5.4 Neurophysiological IssuesParalleling imaging results to the neurophysiological symptoms of LNB is needed to establish causality between symptom and physiological damage.

For example in the case of sensory loss, brain regions corresponding to sensory functions have shown to become affected. In one case, a patient exhibited hearing loss during a bout of LNB. Upon MRI, it was found that lesions in the white matter of subcortical periventricular regions were the cause of hearing loss[45]. Ultimately a lesion in the 8th cranial nerve (vestibulochochlear nerve) was found. Other studies have demonstrated a link between LNB and temporal lobe hypometabolism (abnormal blood flow and deliverance of nutrients) during PET imaging[47]. This may further aid to explain cases of hearing loss. Other MRI scans have shown abnormalities in areas of motor functions; these patients exhibit symptoms similar to amyotrophic lateral sclerosis (Lou Gehrig’s Disease)[27].

Symptomology of LNB can prove to be complex and vast. Variation in observed manifestations are often mistaken for other diseases, which then leads to inaccurate diagnosis, treatment, and preventable death. LNB connections with a few neurophysiological conditions include:

  • Parkinson’s Disease (PD)
    PD is a neurodegenerative disease that involves the degeneration of dopaminergic neurons in the substantia nigra. LNB patients exhibiting similar PD symptoms of tremors, motor rigidity, postural instability, and general lack of voluntary muscle movement also present hypometabolism located to regions of the basal ganglia[10]. Lesions and atrophy to cerebellar and brainstem regions (important in posture and movement) have also been found using MRI [27][48] . Symptoms of supernuclear palsy(where movement is affected) may aid to explain presentation of LNB as PD. In these cases, brain atrophy and diffuse lack of blood flow occur[49] . In a notable case, a patient with classic symptoms of LNB also demonstrated Parkinsonian symptoms and later died[48]. It was found upon autopsy that the patient exhibited striatonigral degeneration, as well as mild atrophy of basal ganglia, depigmentation of substantia nigra and atrophy of cerebellum. This case stands to the point that the specificity of LNB can present itself similar to Parkinson’s disease.

  • Multiple Sclerosis (MS)
    Lesions in LNB patients similar to MS
    LNB patients also shown similar maps of whitematter hypertensivities on MRI to those in MS patients[27]. A recent study also showed that 80% of LNB patients tested have MS-like lesions[50] . Additional similarities between LNB and MS suggests that Borrelia burgdorferi sensu lato might play a causative role in a large percentage of MS cases[51] .

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  • Alzheimer’s Disease (AD)
    Although it is a form of dementia, AD is pathologically defined and includes characteristic molecular abnormalities that lead to changes in brain structure and function. Some LNB cases present similar AD symptoms including: deficits in memory, executive functioning, speech and emotion[27]. Interestingly, studies show that 7 out of 10 AD patients have pathogenic DNA expressed in the brain (post-mortem analysis); this increases the likelihood that many AD cases occur via bacterial infections[52] . It is proposed then that the observed AD plaques and tangles can also be due to chronic infection with Borrelia burgdorferi sensu lato[53] . It has been shown that patents diagnosed with LNB have abnormal production levels of both beta amyloid precursor proteins (alpha-sAPP & beta-sAPP) as well as tau protein (P-tau) as detected in CSF[54] . Moreover their levels are seen to change throughout the course of the disease and with treatment.

5.5 Neuropsychiatric issuesThere is considerable comorbidity associated with LNB presentation and psychological syndromes (symptoms resemble anxiety disorders, depressions, etc.). It is crucial to understand that these psychiatric manifestations are the result of spirochete infection. Improper diagnosis can lead to worsening of symptoms and later stages of psychosis.

One of the hallmark features of late stage LNB is the general decline in cognitive ability and executive functioning. Onset of these symptoms may be explained by observed hypometabolism in frontal and parietal cortices [47]. Issues with frontal areas serve to demonstrate the causal effect of spirochete infection on executive functioning, decision making, planning etc. In addition, as symptoms become progressively worse, greater structural abnormalities become present in these regions. Diffuse hypofusion and lack of blood flow may serve to explain the general cognitive impairment seen in many LNB patients.

Symptoms of memory loss and dementia are linked to the marked deterioration of the brain, reduction in blood flow to general regions, as well as the increase of global atrophy [49]. In the case of one patient, general areas of white matter abnormality was linked to LNB symptoms of encephalopathy. Here lateral, medial frontal, and medial temporal cortices experienced decreased perfusion[55] . Upon treatment, perfusion levels were returned to normal, along with the decrease of psychological symptoms.

LNB connections to neuropsychological conditions include:

  • Panic attacks and Anxiety
    Depending on which areas of the brain the spirochete targets, different brain functions can become affected. In one case, a patient was diagnosed and treated for an anxiety disorder after suffering from frequent panic attacks and bouts of anxiety[56] . Despite treatment for anxiety, symptoms of depression, fatigue and general malaise did not diminish. After diagnostic tests, it was confirmed that the patient had active LNB. Analysis showed hypofusion of both temporal lobes. Treatment for LNB resulted in gradual disappearance of symptoms. This directly shows how spirochete infection can successfully mimic a psychiatric condition.

  • Depression
    The above case also provides evidence for the presence of depressive symptoms during infection with Borrelia burgdorferi sensu lato. In this case, after ridding the body of spirochetes via treatment, the depression subsided. Depression is frequently seen in later stages of LNB, however structural or functional analysis linked to its presentation in LNB patients has not lead to conclusive evidence[57] [58] . It can be thought that the aforementioned global effects of atrophy, lesions and decreases in blood flow can occur in mood centers of the brain [27]. This would explain why many of these patients present depressive symptoms [27].

  • Schizophrenia
    Bouts of mania have previously been reported to be caused by LNB [58]. In some instances, untreated LNB can give rise to psychosis, delusions and hallucinations[57]. In one study it as found that an elderly woman who suffered multiple tick bites and was diagnosed with LNB exhibited symptoms similar to a pain syndrome[2]. This later progressed to psychotic symptoms including hallucinations, somatic delusions and psychosis[2]. Upon treatment for LNB, symptoms were still present and were thought to be due to antibiotic resistance [2].

  • Alice in Wonderland Syndrome (AIWS)
    In extreme cases LNB can present very serious and bizarre symptoms of psychosis and hallucinations. AIWS is a severe syndrome characterized by drastic changes in perception. Patients not only lack ability to judge shape and size, but perceptual hallucinations of other modalities (e.g. touch, hearing) occur[59] . A recent study documented the first ever clinical presentation of LNB as AIWS. A pediatric patient who was experiencing perceptual problems and auditory hallucinations characteristic of AIWS was tested for LNB; results were positive. After successful treatment, all aforementioned symptoms were extinct. Despite this, no abnormal brain structural was reported on MRI scans.

6. Diagnosis

LNB diagnosis is contingent upon the presence of distinct neurologic symptoms, along with validation using laboratory tests and/or medical imaging techniques. The diversity and comorbidity associated with LNB symptoms require the use of definitive laboratory tests. These tests involve collecting blood and/or cerebral spinal fluid(CSF) samples, with a preference for the latter of the two [30].

6.1 Clinical LNB PresentationDiagnostic evaluation begins with characteristic presentation of neurological symptoms associated with LNB[60] . These clinical manifestations are the result of persistent survival of Borrelia burgdorferi sensu lato in CNS tissue. To further confirm infection, patients are then subject to laboratory tests to confirm presence of the bacteria.

6.2 PCRPolymerase Chain Reaction (PCR) is used on CSF samples to amplify and subsequently identify bacterial DNA[61] . Problems with PCR diagnosis entail the fact that contaminations of samples are possible, leading to false-positive and false-negative outcomes [60]. In addition, its sensitivity is only 10-30% in early LNB, and is worse when using blood samples. Its current low sensitivity and specificity make it a poor tool for post-treatment follow-ups [30]. Despite this, PCR has been shown to be best used for late LNB diagnosis. Different PCR protocols tailored to Borrelia burgdorferi sensu lato detection exist and in some cases have proven to be effective. One proposed protocol demonstrated the capability of PCR for LNB spirochete detection using 265 patient serum samples[62] . In all cases the correct diagnosis was made without the presence of false-positives or false-negatives.

6.3 Serological Analysis
Serological analyses are the main diagnostic tool for diagnosis of LNB. This involves the analysis of blood and/or CSF (via spinal tap) to identify specific antibodies [30]. These antibodies include immunoglobulin M (IgM; first and largest antibody produced in response to an infection) and immunoglobulin G (IgG; specific antibody produced during mature/secondary immune response). Serological tests usually involve a two-step approach[60]. ELISAs (Enzyme-linked immunosorbent assay) are first conducted. This has the capability to detect IgM and IgG antibodies raised to the spirochete and has high sensitivity but low specificity. It is for this reason that a secondary test having low sensitivity but greater specificity is used: a western blot (or immunoblot) . A western blot uses antibodies that can target the proteins of interest, and its protocol ultimately provides greater specificity for detection of specific proteins, and therefore IgM and IgG antibodies. This two-step process has become the gold standard for LNB diagnosis.

It is important to note that despite successful treatment, antibodies may still be produced for several months to years[63] . This poses problems for the use of the above methods in post-treatment analysis.

6.4 ImagingAlthough strictly using medical imaging techniques cannot conclusively lead to accurate LNB diagnosis, it may however aid to identify associated brain inflammation, lesions or abnormalities in blood flow. As mentioned previously, MRI scans of LNB cases look similar to those of multiple sclerosis and fibromyalgia, and may demonstrate some marked characteristics as seen in LNB patients [27]. Moreover, SPECT imaging has demonstrated issues in patient blood flow though frontal and temporal regions of the brain. Pairing functional and structural imaging data with serological tests as well as neurological symptoms can lead to greater accuracy in LNB diagnosis and prognosis.

7. Treatment

Borrelia burgdorferi sensu lato is a Gram-negative bacterium, meaning it does not retain crystal violet dye during Gram staining[3]. The Gram staining method itself is useful for classifying bacteria based on differences in cell wall structure, and therefore aids in determining appropriate drug therapies. Treatment has then been tailored towards the manipulation of specific cell wall proteins present on the spirochete coat. Despite the method of intervention, the end goal of treatment is to rid the body of all circulating Borrelia spirochetes[30]. Problems during treatment arise when pathogens remain dormant in cells, or when they become resistant to medications[3]. Since they do not secrete toxins, damage results from host cell immune responses mediating its own cell death; it is for this reason that proper treatment requires not only the eradication of circulating spirochetes, but also must target the aversive immune system reaction.

7.1 Standard TreatmentsDrug therapies are the standard treatment practice used in cases of LNB[30]. These include the administration of antimicrobial and antibiotic drugs that successfully cross the BBB. Different drug types can be administered based on disease progression and age, but most are taken intravenously for brief periods throughout 28 days. Moreover, recommended dosages also differ from children to adults, and the adverse effects of some limit their administration to those who are pregnant.

Antibiotics typically used for treatment of LNB include:

  • Amoxicillin – is an oral bacteriolytic antibiotic often used as an alternative in LNB treatment. It is generally used to treat early presentation of LD in children, but has been shown to successfully treat 7th nerve palsy[30]. Amoxicillin maintains the capacity to affect both Gram-negative and Gram-positive bacteria by inhibiting cross-linkage of polymer chains on the surface of the cell wall[64] .

  • Ceftriaxone & Cefotaxime – are cephalosporin antibiotics that inhibit bacterial cell wall synthesis[65] . They both maintain the ability to destroy Gram-positive as well as Gram-negative bacteria. Ceftriaxone is currently the drug of choice for LNB treatment and is administered intravenously[30], [35]. It has been shown to easily pass through the BBB[30]. It is also highly active against lyme Borrelia in vitro and has a long serum half-life allowing it to be taken only once a day [30].

  • Doxycycline – is a relatively new antibiotic used in LNB treatment. Is administered orally for peripheral infections during LD, but both oral and intravenous administration during LNB have proven effective[35], [66] . Doxycycline is used in lower doses in children, and is not advisable for use in children below the age of 8 since it causes photosensitivity and malformation of teeth[67] . It is also not used if the individual is pregnant. Doxycycline prevents the binding of aminoacyl-tRNA to ribosomes during protein syntheses. This blocks protein synthesis and results not in the death of the bacterium, but the prevention of its growth. New studies have shown that this drug when given orally is as effective as ceftriaxone[68] .

  • Minocycline – is an antibiotic with superior ability in crossing the BBB and is usually used to treat skin infections and acne[69] . Despite being a rather novel treatment for LNB, minocycline has been shown to equal doxycycline effectiveness in treatment trials. It however does include vestibular side effects (dizziness spells and vertigo), which affect patient treatment responses. It is for this reason that minocycline is currently used as an alternative for doxycycline-LNB treatment.

  • Penicillin – is an antimicrobial drug that too crosses the BBB and limits and destroys microbes. Penicillin is usually used as an alternative in most cases of LNB because it is least effective in clearing infection[30], [35]. In studies comparing clinical results in response to oral penicillin versus ceftriaxone, the latter demonstrated better treatment outcome [70] .

7.2 Novel and Controversial TreatmentsOriginally identified in the mid 1970s, LNB is still a relatively new disease. Early interventions included the use of silver and malriotherapy (which proved to be deadly). The search for novel and more efficient treatments aim for achieving quick clearance of the pathogen from the body and focus on antibiotic drug interventions. Despite this, other treatments have been proposed, many of which maintain little or no scientific evidence.

Some recent and/or controversial treatments include:

  • Combination Antibiotic Therapy – attempts to solve issues with using monotreatment approaches to antibiotic therapy (i.e. deliverance of one drug type during treatment) [71] . Specifically, mono-drug treatments may fail to clearly rid the infection, and is often the cause of antibiotic resistance. Combination antibiotic therapy is the idea of using multiple medicines that achieve a synergistic activity in the body to completely and effectively eliminate spirochetes. Whether combination antibiotic therapy is better then gram-negative bacteria remains controversial, and clinical trials tailored to LNB have yet to occur[72] .

  • Treatments for Inflammatory Response – part of the problem in LNB is the intense inflammatory responses associated with it. Immune T-cells searching for antigens of the bacterial spirochete seek cells infected and displaying the antigen[73] . Immune cells then inflame and consequently destroy their own cells. Controlling these inflammatory and immune responses are important. In a recent study, a LNB model was created using infected astrocytes and glia of the rhesus monkey[74] . It was found that treatment with doxycycline and minocycline reduced the production of tumor necrosis factor-α, interleukin-6 and interleukin-8. Down-regulation of these immune response-stimulating proteins may demonstrate the potential for both doxycycline and minocycline to serve a dual treatment effect (i.e. destroying spirochetes as well as decreasing immune response).

  • 800px-HBO_Chamber2008.jpg
    A hyperbaric Chamber.
    Hyperbaric oxygen therapy (HBOT)
    – is a high-pressure oxygen treatment usually preformed on deep-sea divers suffering from decompression sickness, or individuals suffering from smoke inhalation. Contradictory anecdotal evidence present HBOT as a possible therapy option despite the lack of clinical evidence. Moreover, the Infectious Diseases Society of America (IDSA) does not recommend its use in treatment of LNB [75] . Despite this, recent evidence using mice models suggest that this therapy option seems to increase the mobilization of stem and progenitor cells throughout the body, and may therefore demonstrate potential for the repair of damaged organs[76] . This in turn might have an influence in increasing treatment outcome of LNB, although supporting scientific evidence does not exist.

  • Bismacine – is also known as chromacine. Bismacine contains the chemical element bismuth (Bi on periodic table), which is similar to arsenic. Its use in treating LNB has not proved effective with at least two deaths reported during clinical treatment [77] . It is also not recommended by the FDA as a safe or credible treatment option.

  • Biodetoxification Quackery – occurs when self-profit organizations selling LNB drugs claim that they aid to rid and detoxify compounds produced by the spirochete. These drugs are considered to be quackery, as it has been documented that Borrelia burgdorferi sensu lato itself produces no neurotoxins [3].

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