Clin Microbiol Infect 2012; 18: 1027–1032
Although tick-borne encephalitis (TBE) has been recognized in Europe for more than 70 years and has been the topic of numerous reports, information on the involvement of facial nerves in the course of the disease is limited. Our study conducted at a single medical centre revealed that facial nerve involvement in the course of TBE in Central Europe is (i) infrequent—it was found in only 11 of 1218 (0.9%) consecutive adult patients diagnosed with TBE; (ii) manifests with unilateral or rarely bilateral peripheral facial palsy (PFP) (nine and two patients, respectively); (iii) appears late in the course of acute illness—in our patients 10–20 days after the onset of the meningoencephalitic phase of TBE, and often after defervescence (in 8/11 patients; 6–13 days after normalization of body temperature); (iv) develops more often in patients with more severe illness, i.e. more frequently in those with encephalitic than in those with meningitic clinical presentation, and more commonly in patients with monophasic than biphasic illness; and (v) has a favourable outcome—our patients had a clinically complete recovery from PFP within 7–90 (median 30) days after its onset. Moreover, the finding of Borrelia infection in 3/11 (27.3%) patients (diagnosis of confirmed Lyme neuroborreliosis was established in 1/11 patients and two patients fulfilled criteria for possible Lyme neuroborreliosis) suggests that in countries where TBE and Lyme borreliosis are endemic, concomitant infection with Borrelia burgdorferi sensu lato should be considered and searched for in patients who develop PFP in the course of TBE.
The most important tick-borne diseases in Slovenia are Lyme borreliosis and tick-borne encephalitis (TBE). Their incidence rates are among the highest in Europe . The causative agents of the diseases—Borrelia burgdorferi sensu lato and TBE virus (TBEV)—are transmitted by the hard tick Ixodes ricinus, which is the prevalent tick species in Slovenia .
Three subtypes of TBEV (European, Siberian and Far Eastern subtypes) that cause the disease result in similar but not identical illnesses. More than half of patients with TBE caused by the European subtype of TBEV have a characteristic biphasic course of illness. The initial phase, which corresponds to viraemia and lasts for 1–8 days, is characterized by fever, headache and malaise. It is followed by an improvement or even an asymptomatic interval of about 1 week, and then by signs and symptoms of neurological involvement. The second phase presents as meningitis, meningoencephalitis, or meningoencephalomyelitis in 50%, 40% and 5–10% of adult patients, respectively. The severity of illness increases with age: the predominant manifestation in children is meningitis whereas in elderly people meningoencephalitis prevails. The majority of patients recover completely. The reported fatality rate of TBE in Europe is 0.5–2% [3,4].
In TBE the involvement of cranial nerves has been reported only occasionally and in only a subset of patients with cranial nerve involvement does facial palsy develop [5–22]. This is in contrast to Lyme borreliosis, which has been associated with a wide range of neurological disorders including meningitis, cranial neuritis, radiculoneuritis, peripheral neuritis in association with acrodermatitis chronica atrophicans and, rarely, meningoencephalitis and encephalopathy, and in which peripheral facial palsy (PFP) is common. In fact, PFP is by far the most frequent manifestation of cranial nerve involvement, may be the only neurological manifestation during early disseminated borrelial infection, may develop without antecedent erythema migrans, sometimes before measurable antibody response, and is, as a rule, associated with cerebrospinal fluid (CSF) pleocytosis . Concomitant infections with B. burgdorferi sensu lato and TBEV have been reported . Hence, at least in some patients PFP that develops in the course of TBE might have been the result of a concomitant borrelial infection. According to a literature review, this potential correlation has not been tested systematically.
The purpose of this study was to establish the frequency and characteristics of facial palsy in adult patients with TBE and to assess the occurrence of borrelial infection in the group of patients who develop PFP in the course of TBE.
Patients and Methods
At our institution, a regular initial approach in all patients with clinical signs/symptoms indicating meningitis or meningoencephalitis is to obtain a detailed epidemiological and medical history, to perform physical examination, to carry out routine blood and CSF tests including cell counts, concentration of total proteins, glucose, albumin, IgG, IgA and IgM, as well as to test for infection with TBEV and B. burgdorferi sensu lato. After hospitalization, patients with TBE are followed for at least 8 weeks whereas those in whom borrelial infection is demonstrated are generally followed for 1 year.
All patients older than 15 years with TBE, hospitalized at the Department of Infectious Diseases, University Medical Centre Ljubljana, Slovenia, during the period from January 2003 to December 2009, in whom facial palsy developed during their illness, were included in the present study.
The presence of serum IgM and IgG antibodies against TBEV was determined using the Enzygnost® Anti-TBEV (IgM, IgG) test (Dade Behring Marburg GmbH, Marburg, Germany) performed according to the manufacturer’s instructions.
The course of illness in patients with TBE and associated facial palsy was compared with the course in patients with TBE without facial palsy. For each patient with TBE associated with facial palsy, ten other patients diagnosed with TBE at our institution in the same year, and who were of the same sex and the most comparable age, were included in the control group.
All of these patients were routinely tested for borrelial infection at presentation (serum and CSF borrelial antibodies, culture of CSF) and 6–8 weeks later (determination of borrelial antibodies in serum). Borrelial serum and CSF IgM and IgG antibody titres were determined by an in-house indirect immunofluorescence assay using a local skin isolate of Borrelia afzelii for antigen . Serum antibody titres ≥1 : 256 and CSF antibody titres ≥1 : 16 were interpreted as positive. Intrathecal specific antibody synthesis was assessed by calculation of IgM and IgG antibody index. Values >2 were interpreted as indicative for intrathecal antibody production .
The CSF specimens were cultured for the presence of Borrelia in modified Kelly–Pettenkofer medium. Specimens were incubated at 33°C and checked weekly for the presence of Borrelia for 9 weeks. The species of the isolated Borrelia strains were identified by polymerase chain reaction or by pulsed-field gel electrophoresis after restriction by MluI restriction enzyme as reported previously .
Diagnosis of TBE was considered to be confirmed by the following findings: fever, clinical signs/symptoms of meningitis or meningoencephalitis, an elevated CSF leucocyte count (>5 × 106/L) and the presence of serum IgM and IgG antibodies to TBEV. The TBE was assessed clinically as mild (only signs/symptoms of meningeal involvement), moderate (monofocal neurological signs and/or mild to moderate signs/symptoms of central nervous system dysfunction) or severe (multifocal neurological signs and/or signs/symptoms of severe dysfunction of central nervous system).
Lyme neuroborreliosis was interpreted as being confirmed by elevated CSF cell counts and the isolation of B. burgdorferi sensu lato from CSF, and/or demonstration of intrathecal borrelial antibody production, and/or seroconversion to borrelial antigens. In patients with positive but unchanging borrelial serum antibody titres and without other previously mentioned microbiological criteria, the diagnosis of Lyme neuroborreliosis was considered possible.
Categorical data were analysed with Yates’ corrected chi-square test or Fisher’s exact test (two-tailed), whereas quantitative data were analysed by the Kruskal–Wallis test, using EPI info version 3.4.3. software (Centers for Disease Control, Atlanta, GA, USA). A p value <0.05 was interpreted as statistically significant.
Of 1218 adult patients (705 males, 513 females; median age 56 years, range 15–91 years), diagnosed with TBE at our department from 2003 to 2009, 11 (0.9%) developed PFP during the course of their illness—two had bilateral and nine had unilateral facial nerve involvement—central facial palsy was not found.
In the group of 11 patients with PFP there were ten men and one woman, with a median age of 53 years (range, 41–76 years). Eight (72.7%) patients had a monophasic course of TBE and only three (27.3%) patients had a biphasic course of TBE. The illness was relatively mild in one (9.1%) patient who presented with signs/symptoms of meningitis, moderately severe in nine (81.8%) patients with signs/symptoms of meningoencephalitis, and severe in one (9.1%) patient with meningoencephalomyelitis who had pronounced consciousness disturbances and required mechanical ventilation. In the last patient, severe pain in the shoulders preceded paresis of shoulder muscles, which appeared on the 8th day of his illness and was followed by bilateral facial palsy 9 days later (17th day of the illness).
One of the 11 patients developed TBE in spite of complete vaccination; he received the third dose of basic vaccination against TBE 4 years before the onset of his illness, which had a relatively mild course. In this 41-year-old patient the diagnosis of TBE was ascertained by demonstration of intrathecal synthesis of specific IgG antibodies.
Facial nerve involvement appeared 15 (6–30) days after the beginning of TBE (defined as the first day of fever), and 12 (10–20) days after the onset of the meningoencephalitic phase of the illness. In eight (72.7%) patients (in 6/8 with monophasic disease and in 2/3 with a biphasic course of TBE) PFP developed in the afebrile period, i.e. 10 (6–13) days after defervescence. All the patients had a clinically complete recovery of PFP within 7–90 (median 30) days after its onset. Patients were hospitalized for median 9 (range 6–34) days. None of them died during acute illness.
At admission to hospital, serum borrelial immunofluorescent assay IgG antibody titre ≥1 : 256 was found in two (18.2%) patients, whereas in one (9.1%) seronegative patient, who satisfied criteria for confirmed Lyme neuroborreliosis, B. afzelii was isolated from the CSF. All three patients had unilateral PFP, were treated with intravenous ceftriaxone 2 g/day for 14 days, and had an uneventful outcome. The duration of PFP in patients with TBE and associated Lyme neuroborreliosis was comparable to the duration of PFP in TBE patients without borrelial co-infection: 30 (14–30) days versus 37.5 (7–90) days, respectively; p 0.532.
Basic demographic and clinical characteristics for 11 patients with TBE in whom PFP developed in the course of their illness and 110 sex-matched and age-matched control patients who were diagnosed with TBE without PFP in the same year, are depicted in Table 1.
|Characteristics||TBE + PFP n (%)||TBE without PFP n (%)||p|
|Patient sex: female/male||1 (9.1)/10 (90.9)||10 (9.1)/100 (90.9)||1.000a|
|Age (years): median (range)||53 (41–76)||54 (41–76)||0.642b|
|Tick bitec||9 (81.8)||72 (65.5)||0.335a|
|>1 tick bite||4/9 (44.4)||28/72 (38.9)||0.734a|
|Biphasic course of TBE||3 (27.3)||54 (49.1)||0.287a|
|Severity of TBE:|
|Mild||1 (9.1)||48 (43.6)||0.028a|
|Moderate||9 (81.8)||56 (50.9)||0.100a|
|Severe||1 (9.1)||6 (5.5)||0.496a|
|Anti-oedematous treatmentd||7 (63.6)||27 (24.5)||0.011a|
Patients with TBE and associated PFP did not differ significantly from control subjects for the majority of basic demographic and clinical findings (Table 1) as well as the frequency of demonstration of Borrelia infection (Table 2). However, a higher proportion of patients with meningoencephalitis/meningoencephalomyelitis (90.9% versus 56.4%; p 0.028) as well as a higher ratio of patients who received anti-oedematous treatment (63.6% versus 24.5%; p 0.011) indicate that among the patients who develop PFP in the course of TBE, the acute illness was more severe than in those without facial nerve involvement (Table 1).
|TBE + PFP n (%)||TBE without PFP n (%)||pa|
|Serum IgG (≥1 : 256)||2 (18.2)||7 (6.4)||0.190|
|CSF IgG (≥1:16)||0||1 (0.9)||1.000|
|Intrathecal IgG antibody production (Index >2)||0||1 (0.9)b||1.000|
|Isolation of Borrelia from CSF||1 (9.1)c||1 (0.9)d||1.174|
|Any indication of Borrelia infection||3 (27.3)||9 (8.2)||0.078|
Although TBE has been recognized in Europe for more than 70 years, has been of public health importance in several countries , and has been the topic of numerous reports, relatively little is known about the involvement of cranial nerves in the course of the illness. Acute involvement of most cranial nerves with often favourable outcome has been described; it was mainly associated with the impairment of ocular, facial and pharyngeal motor function, but vestibular and hearing defects were also encountered [3,4]. Concerning the facial nerve, it is evident that it can be involved; however, the type of impairment, the frequency of the damage, the circumstances in which it occurs and when in the course of the illness it appears, are less clear. Among case series consisting of more than 100 patients with TBE that were published during the last 50 years [5–22], we were able to find 13 articles with data on cranial nerve involvement [5,7–18], including nine reports with information on facial nerve damage (Table 3). In these case series cranial nerve involvement was found in 0.8–11% of patients and facial palsy in 0.8–2.6% of patients. However, in the majority of the articles the information on cranial nerve involvement was superficial. For example, in patients reported to have facial nerve damage, data enabling unambiguous differentiation between upper and lower motor neuron involvement were not available. Our review of 1218 adult patients diagnosed with TBE during the 7 years of the study revealed 11 (0.9%) patients with facial nerve involvement; all of them had PFP.
|Reference||No. of patients with TBE (No. of analysed)||No. (%) of patients with cranial nerve involvement||Affected cranial nerves except VIIth No. (%) of patients||No. (%) of patients with facial palsy|
|Duniewicz et al. ||633a||29 (4.6)||III 3 (0.5) |
VIII 2 (0.3)
IX, X, XI 10 (1.6)
|VII 14 (2.2)|
|Radsel-Medvescek et al. ||315a||11 (3.5)||NA||NA|
|Wahlberg et al. ||126a||2 (1.6)||NA||2 (1.6)|
|Haglund et al. ||143 (114)b||1 (0.9)||0||1 (0.9)|
|Kaiser ||656a||74 (11)c||III 3 (0.5) |
V 2 (0.3)
VI 21 (3.2)
VIII 27 (4.1)
IX, X 16 (2.5)
XI 17 (2.6)
XII 9 (1.4)
|Čižman et al. ||133d||1(0.8)c||0||1 (0.8)|
|Mickiene et al. ||133b||7 (5.3)||NA||NA|
|Grygorczuk et al. ||152b||5 (3.3)c||III 2 (1.3) |
IX, X 1 (0.7)
|Lesnicar et al. ||371d||14 (3.8)||NA||1 (0.3)|
|Logar et al. ||448b||5 (1.1)||NA||NA|
|Fritsch et al. ||116d||2 (1.7)||0||2 (1.7)|
|Mišić-Majerus et al. ||133 (124)b||11 (8.8)||NA||NA|
|Czupryna et al. ||687 (621)b||19 (3)c||III 5 (0.8) |
IV 2 (0.3)
VI 1 (0.2)
IX 4 (0.6)
X 4 (0.6)
XI 1 (0.2)
Information from the literature suggests that the occurrence of cranial nerve involvement varies with the severity of clinical presentation of TBE. Mickiene et al.  reported cranial nerve injury (no case of facial involvement) in 5.3% (7/133) of patients in the acute stage of TBE; the majority of them had the severe form of the disease. Haglund et al.  found unilateral facial palsy in only one out of 114 patients with TBE; the patient had a very severe illness with tetraparesis and unfavourable outcome. Kaiser  established involvement of cranial nerves in 11% of 656 patients with TBE. Facial palsy was present in 2.6% (17/656) of patients and its frequency ranked second after the impairment of nervus vestibularis. It was found in 3% of patients with meningitis, in 2.6% of patients with meningoencephalitis, and in 15.1% of patients with meningoencephalomyelitis. Facial palsy was more frequently established in adults than in children. In a few studies in which only children with TBE were included, facial palsy was very rare and as a rule developed in patients with the severe course of the disease [11,14,16].
Our results further corroborate published information on the association of PFP and the severity of TBE. Comparison of the 11 patients with TBE in whom PFP developed during the course of their illness and 110 sex-matched and age-matched control patients who were diagnosed with TBE but without PFP in the same year (Table 1) revealed a higher proportion of patients with meningoencephalitis/meningoencephalomyelitis (90.9% versus 56.4%; p 0.028) as well as a higher ratio of patients who received anti-oedematous treatment (63.6% versus 24.5%; p 0.011) in the group of patients with PFP. These findings indicate that in the group of patients with TBE and PFP the acute illness is more severe than in those without facial nerve involvement. In addition, the majority of our patients with PFP (8/11) had a monophasic course of TBE; according to some authors monophasic presentation is associated with a more severe acute course of the disease [3,8,20–22,28].
In our group of 11 patients with TBE and PFP facial nerve damage appeared late in the course of TBE, median 12 (10–20) days after the onset of the meningoencephalitic phase of the illness, in the majority of patients (8/11, 72.7%) in a febrile period, i.e. 10 (6–13) days after defervescence. These findings are comparable to the results of Duniewicz et al.  who reported that facial palsy developed more often after defervescence (10/14, 71.4%) than during the febrile phase of acute disease. They point to the need for clinical follow up of patients with TBE and pose further questions about the pathogenesis of this rare manifestation, which remains to be elucidated. A simple clinical approach that was used in our study does not enable an insight into the pathogenesis of PFP. However, a finding that one of our patients with TBE and PFP was vaccinated against TBE might indicate that the presence of antibodies induced by vaccine could potentially have been associated with the development of PFP. It has been known that the presence of a specific antibody may enhance disease symptoms for a variety of viruses including dengue virus and also TBEV .
The findings of the present study indicate that some patients with TBE also have borrelial infection. The diagnosis of confirmed Lyme neuroborreliosis was established in one of 11 (9.1%) patients in whom PFP developed in the course of TBE whereas two (18.2%) patients fulfilled the criteria for possible Lyme neuroborreliosis (Table 2). All three patients had unilateral PFP, were treated with intravenous ceftriaxone 2 g/day for 14 days, and had an uneventful outcome. The duration of PFP in patients with TBE and associated Lyme neuroborreliosis was comparable to the duration of PFP in TBE patients without borrelial co-infection. The diagnosis of borrelial infection is important because patients with PFP in association with Lyme borreliosis should receive antibiotic therapy, not primarily for the purpose of expediting recovery from the paralysis, which will usually resolve within a few weeks regardless of whether antimicrobial therapy is given, but rather to prevent later complications .
In conclusion, facial nerve involvement in the course of TBE in Central Europe is infrequent, manifests with unilateral or rarely bilateral PFP, appears late in the course of acute illness (quite often after defervescence) and more often in patients with encephalitic that in those with meningitis clinical presentation, and has a favourable outcome. In European countries, where TBE and Lyme borreliosis are endemic, such as Slovenia, concomitant infection with B. burgdorferi sensu lato should be considered and searched for in patients who developed PFP in the course of TBE.
All authors declare no potential conflicts of interest.