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Listerial brainstem encephalitis--treatable, but easily missed.

Listeria monocytogenes is a very common intracellular Gram-positive coccobacillus occurring in the soil, and humans may be affected via the oral route from contaminated food. The organism has a remarkable resistance to eradication during food processing, has unique virulence factors, [1, 2] and is an important cause of food-borne epidemic disease with high associated mortality. [3] Following ingestion, infection occurs across the intestinal epithelium and spreads to the liver, where it becomes established within the cytosol of macrophages. Macrophages may then traffic infection via the bloodstream to the meninges and fetoplacental unit. [1] The disease usually presents as a febrile diarrhoeal illness, but may also cause septicaemia, meningitis and chorioamnionitis. Listerial meningitis may be the third most common cause of acute community-acquired bacterial meningitis. [2]

Listerial brainstem meningitis (LBE), however, is an uncommon, sporadically occurring form of listerial infection that progresses rapidly and is invariably fatal unless treated early. [3-5] Cases are often undetected. [5] It is characterised by a prodromal febrile illness followed within 4-10 days by the abrupt onset of cranial nerve deficits associated with encephalopathy, hemiparesis, hemisensory loss and/ or cerebellar signs. [3-5] Unlike the other forms of central nervous system (CNS) listeriosis, LBE is striking in respect of the stepwise development of brainstem signs in the absence of meningism. This presentation is probably accounted for by a novel route of infection that exploits retrograde axonal transport to the brainstem along the cranial nerves that supply the oropharynx. [2, 6]


We report on six patients with LBE, of whom five were managed or co-managed by the neurology unit at Tygerberg Hospital, Western Cape, South Africa, during the period January-June 2012. Definite cases were defined as cases with a compatible clinical syndrome (prodrome followed by stepwise neurological deficits due to brainstem disease) and microbiological demonstration of L. monocytogenes in blood, cerebrospinal fluid (CSF) or brain tissue. Probable cases were defined as cases with a compatible clinical syndrome with ancillary tests (brain imaging and CSF analysis) supporting the diagnosis and evidence of improvement after commencement of antilisterial therapy.

The Stellenbosch University Human Research Ethics Committee approved the reporting of clinical material (S13/10/223).

Case report

The index case (patient 1) was a 59-year-old woman who presented with a 1-week flu-like illness followed by ataxia and sensory loss involving the face. Thereafter she developed a deteriorating level of consciousness and died within 3 weeks.

At onset she complained of fever, dizziness and unremitting frontal headache, and she was treated with telithromycin followed by moxifloxacin for suspected sinusitis. One week later, she developed hoarseness, numbness of the left cheek and ataxia of the left arm. A chest radiograph was normal. Magnetic resonance imaging (MRI) of the brain showed signal abnormalities in the pons and left middle cerebellar peduncle on fluid-attenuated inversion recovery (FLAIR) sequences, with subtle contrast enhancement on T1-weighted images. Intravenous (IV) methylprednisolone was given for 3 days for a presumptive diagnosis of acute disseminated encephalomyelitis (ADEM), during which her condition remained stable and she was apyrexial. However, a day later, she developed a fever and became comatose, and was found to have bilateral papilloedema. CSF protein and glucose levels were normal, and there were 4 polymorphonuclear cells per high-power field on microscopy. A CSF Gram stain was negative, and neither the CSF nor initial blood cultures yielded growth after 5 days of incubation. Repeat MRI of the brain showed extension of signal abnormalities into both cerebellar peduncles, the cerebellum and rostrally into the basal ganglia. There was no clinical response to treatment with IV corticosteroids and acyclovir. Subsequent MRI brain imaging revealed progression of disease to involve the upper cervical cord, brainstem, cerebellum, bilateral basal ganglia and rostral left cerebral hemisphere. A repeat CSF sample was acellular with normal chemistry and microscopy. The patient died after 17 days of illness. Blood cultures taken on day 15 as well as CSF cultures taken on day 17 cultured L. monocytogenes, and at autopsy L. monocytogenes microabscesses were confirmed (Fig. 1).


We report two definite (patients 1 and 4) and four probable cases of LBE. The clinical data and ancillary tests are summarised in Tables 1 and 2, respectively. LBE typically begins with a prodrome of up to 16 days (median 4 days), [3-4] with isolated cases reported to have prodromes of more than a month. [3] In our series, the median time before the onset of neurological signs was 5.5 days. Headache (73%), fever (85%) and nausea or vomiting (64%) are the most commonly reported early features, [3, 4] but these were absent in a third of our patients. Mental state at admission is often preserved (59%). [3] The prodrome is followed by the onset of focal signs of lower brainstem and cerebellar involvement. Patients frequently present with asymmetrical cranial nerve dysfunction (VII, VI, IX, X and V, in order of descending frequency). [3, 5] Untreated patients deteriorate over days with new cranial nerve deficits and the emergence of crossed' or bilateral long-tract signs (hemiparesis more often than hemisensory loss), cerebellar signs and/or encephalopathy. At maximal evolution, most patients have combined cranial nerve deficits and long-tract signs (81%), and more than half have cerebellar signs. [3, 5] Cranial nerve involvement is seen in all patients at the nadir of the illness. Frequently, noncontiguous cranial nerve nuclei will be affected during the course of the illness; for instance, patient 6 had left trigeminal sensory involvement, right abducens palsy and lower motor neuron facial weakness, as well as a left palatal palsy (cranial nerve X), indicating multifocal brainstem involvement. Respiratory failure due to involvement of the medulla may occur early and necessitate ventilatory support. [3, 5] A reduced level of consciousness was present in four of the six patients.

The differential diagnosis of brainstem encephalitis varies depending on population and geographical region. [7] Broadly, this presentation may be due to demyelination (e.g. multiple sclerosis, ADEM) or autoimmune/inflammatory (e.g. Behcet's disease, paraneoplastic), infectious and very rarely neoplastic diseases (e.g. lymphoma). [7, 8] Infectious causes in adults include viruses, such as entero- and herpesviruses. Surprisingly, however, a bacterial infection such as listeria is one of the most common infectious causes of brainstem encephalitis. In an SA setting, tuberculosis and progressive multifocal leucoencephalopathy due to JC virus infection are also important considerations in the setting of progressive brainstem disease.

With CNS invasion, listeriosis may target the meninges resulting in the typical clinical picture of acute/subacute bacterial meningitis, [2] but unlike other bacteria may also target the brain parenchyma and specifically the rhombencephalon (pons, medulla, cerebellum). In humans, brainstem infection occurs in up to 11-24% of patients with CNS listeriosis. [3, 5] In LBE, it appears that food-borne bacteria invade the brainstem by retrograde axonal migration along the oropharyngeal cranial nerves. [2] A postmortem study of nine human cases of LBE revealed brainstem microabscesses that were prominently distributed within the nuclei, tracts and intraparenchymal portions of the cranial nerves innervating the oropharynx (V, VII, IX, X and XII). [9] Injection of listerial bacteria into the facial nerves of mice was followed 5-10 days later by ipsilateral CNS deficits that were prevented by section of the nerve proximal to the inoculation site. [10] Similarly, injection of listerial bacteria into the sciatic nerves of mice resulted in a flaccid paraparesis that was prevented by sectioning the sciatic nerve proximal to the inoculation site. [10] Actin-dependent locomotion of L. monocytogenes along microtubules has been demonstrated in other eukaryote cells and remains the most plausible explanation for bacterial propagation along axons. [11]

Factors predisposing to LBE in humans have not been identified. Unlike listerial meningitis, where two-thirds of patients are immunosuppressed by medication, advanced age or comorbid disease, LBE has been reported to occur mainly in immunocompetent adults. [3] Of our patients, three had comorbid conditions such as immunosuppressant therapy, diabetes, alcoholism and HIV infection.

Of importance, CSF abnormalities in LBE are not typical of bacterial infections of the CNS, and one in five patients may have normal CSF on initial sampling. [3] A relatively normal CSF glucose level, moderate lymphocytic pleocytosis and a moderately increased CSF protein level may mistakenly be attributed to viral or mycobacterial infection, or, as in one of our patients, to inflammatory demyelination. [3-5] The CSF was normal in one of our patients, and patient 3 had a neutrophil-predominant mild pleocytosis.

In a review of patients with LBE by Armstrong and Fung, [3] CSF Gram stains were positive in only 10% of cases, with CSF cultures positive in 33-41% and blood cultures in 61%. Positive cultures were obtained in two of our six patients (two on blood, one on CSF).

MRI is the radiological investigation of choice in the diagnosis of brainstem disease. In our series, findings on MRI were abnormal in all patients studied (five scanned, see example in Fig. 2), and showed T2 signal change in the brainstem, cerebellar peduncles and cerebellum associated with variable enhancement on contrasted T1-weighted images. Computed tomography (CT) is less sensitive than MRI in LBE; [3-5] two of five patients in this study had abnormal findings. Striking cranial nerve enhancement may be seen on MRI, [12] or, less often, on CT, and was present in three of our six patients (two MRI, one CT). Radiological appearances are nonspecific, however, and in a region of high tuberculosis prevalence listerial brainstem abscesses may be radiologically indistinguishable from tuberculomas. In the absence of microbiological or histopathological confirmation, empiric treatment for both L. monocytogenes and Mycobacterium tuberculosis may have to be considered. Rapid radiological and clinical improvement would favour listeriosis over tuberculosis as the likely cause.

Supratentorial abscess formation may occur in conjunction with LBE and was present in patients 1 and 6 in our series. [3, 13] Following the prodrome and initial neurological deficit, patient 6 received high-dose corticosteroids for a presumed diagnosis of ADEM, after which disease progression appeared stable until abrupt deterioration on day 35. MRI showed left thalamic and parietal lobe abscess formation. A biopsy specimen of brain tissue for culture, obtained 5 days after starting intravenous ampicillin, was negative. The patient made a remarkable recovery.

High-dose ampicillin is the drug of choice. The recommended treatment is ampicillin 2 g IV 4-hourly for 21 days, [14] although some authors suggest longer treatment periods and the addition of an aminoglycoside. [15] Gentamicin acts synergistically with ampicillin and may be added in patients with immune impairment.!3! Co-trimoxazole is an acceptable alternative in penicillinallergic patients. [14] It is important to note that third-generation cephalosporins, commonly recommended as first-line therapy for bacterial meningitis of unknown cause, have no activity against Listeria species.

Untreated patients invariably die, [3-5] usually within 5-18 days after symptom onset. [3] Treated survival rates of 49-64% have been reported. [3, 4] Early treatment with ampicillin is associated with improved survival (76%) compared with delayed treatment or initial treatment with inappropriate antibiotics such as cephalosporins. [3] Neurological dysfunction improves within 2-7 days of drug initiation. [4] In our series, no patient suffered disabling sequelae.

Small epidemics of listeriosis from contaminated food sources are frequently reported in countries where the infection is notifiable, and the source of the contaminated food has often been identified. Given the high fatality rate of listeriosis, contaminated food is an important public health hazard. In SA, however, the disease is not notifiable at present. It is of interest that, as three patients in this series presented within 6 months of each other and came from geographically closely related areas, the infection may have been caused by a common contaminated food source.


[1.] Freitag NE, Port GC, Miner MD. Listeria monocytogenes from saprophyte to intracellular pathogen. Nat Rev Microbiol 2009;7(9):623-628. []

[2.] Disson O, Lecuit M. Targeting of the central nervous system by Listeria monocytogenes. Virulence 2012;3(2):213-221. []

[3.] Armstrong RW, Fung PC. Brainstem encephalitis (rhombencephalitis) due to Listeria monocytogenes: Case report and review. Clin Infect Dis 1993;16(5):689-702. []

[4.] Uldry PA, Kuntzer T, Bogousslavsky J, et al. Early symptoms and outcome of Listeria monocytogenes rhombencephalitis: 14 adult cases. J Neurol 1993;240(4):235-242. []

[5.] Antal E-A, Dietrichs E, L0berg E-M, Melby KK, Maehlen J. Brain stem encephalitis in listeriosis. Scand J Infect Dis 2005;37(3):190194. []

[6.] Madarame H, Seuberlich T, Abril C, Zurbriggen A, Vandevelde M, Oevermann A. The distribution of E-cadherin expression in listeric rhombencephalitis of ruminants indicates its involvement in Listeria monocytogenes neuroinvasion. Neuropathol Appl Neurobiol 2011;37(7):753-767. []

[7.] Jubelt B, Mihai C, Li TM, Veerapaneni P. Rhombencephalitis/brainstem encephalitis. Curr Neurol Neurosci Rep 2011;11(6):543552. []

[8.] Moragas M, Martinez-Yelamos S, Majos C, Fernandez-Viladrich P, Rubio F, Arbizu T. Rhombencephalitis: A series of 97 patients. Medicine (Baltimore) 2011;90(4):256-261. []

[9.] Antal E-A, L0berg E-M, Dietrichs E, Maehlen J. Neuropathological findings in 9 cases of Listeria monocytogenes brain stem encephalitis. Brain Pathol 2005;15(3):187-191. []

[10.] Antal E-A, L0berg E-M, Bracht P, Melby KK, Maehlen J. Evidence for intraaxonal spread of Listeria monocytogenes from the periphery to the central nervous system. Brain Pathol 2001;11(4):432-438. []

[11.] Dons L, Jin Y, Kristensson K, Rottenberg ME. Axonal transport of Listeria monocytogenes and nerve-cell-induced bacterial killing. J Neurosci Res 2007;85(12):2529-2537. []

[12.] Moro A, Albino PHDC, Bresciani AP, et al. Rhombencephalitis caused by Listeria monocytogenes with striking involvement of trigeminal nerve on MR imaging. Arq Neuropsiquiatr 2011;69(3):568-569. []

[13.] Soares-Fernandes JP, Beleza P, Cerqueira JJ, et al. Simultaneous supratentorial and brainstem abscesses due to Listeria monocytogenes. J Neuroradiol 2008;35(3):173-176. []

[14.] Van de Beek D, Brouwer MC, Thwaites GE, Tunkel AR.

Advances in treatment of bacterial meningitis. Lancet 2012;380(9854):1693-1702. [ 6736(12)61186-6]

[15.] Mylonakis E, Hohmann EL, Calderwood SB. Central nervous system infection with Listeria monocytogenes: 33 years' experience at a general hospital and review of 776 episodes from the literature. Medicine (Baltimore) 1998;77(5):313-336. []

Accepted 1 August 2014.

Pearl Fredericks and Jonathan Carr are affiliated to the Division of Neurology, Department of Internal Medicine, Tygerberg Hospital and Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, Cape Town, South Africa. Marcell Britz is a specialist neurologist in private practice in Port Elizabeth, Eastern Cape, South Africa. Roland Eastman and Kathleen Bateman are affiliated to the Division of Neurology, Department of Medicine, Groote Schuur Hospital

and Faculty of Health Sciences, University of Cape Town, South Africa.

Corresponding author: K Bateman (

Table 1. Clinical presentation, course and outcomes


               1                  2

Geographical   PE, E Cape         Caledon,
location                          W Cape

Age            59                 37

Gender         F                  M

Comorbid       Recent             Hpt, DM
disease        sinusitis

Length of      6                  3

Symptoms       HA, dizziness,     Fever,
(in order      facial numbness,   dizziness,
of onset)      hoarseness         ataxia

Signs (in      Fever, L CN V2     Fever, nystag,
order of       (S), CN X, L arm   L dysmetria,
onset)         dysmetria, coma    gait ataxia
                                  (d3); drowsiness,
                                  apnoea (d6); bilat
                                  CN IV, L CN VII
                                  (LMN), nystag, CN
                                  X, mild
                                  quadriparesis (d8)

Antibiotics    TEL, MXF           AMX (d2), CRO (d3)
prior to

Treatment      MP (dll)           AMP (d8); ACV
                                  (d5); RHZE (d8-d22)

Nadir                             d10

Outcome        Death (dl7)        Alive, no focal
                                  signs (d41)


               3                      4

Geographical   Paarl,                 Kleinmond,
location       W Cape                 W Cape

Age            51                     36

Gender         M                      F

Comorbid       HIV *, ethanol         RA on
disease        abuse                  immuno-

Length of      5                      1

Symptoms       Unilat HA;             fever, dysarthria,
(in order      N&V, gait ataxia,      dysphagia,
of onset)      dysphonia (d5); L      numb L arm
               facial numbness,
               D/V (d6)

Signs (in      R Horner's,            Fever, coma,
order of       bilat CN VI, nystag,   bilat ptosis, bilat
onset)         L CN V (S), L          gaze palsies, skew
               CN X, worsening        deviation, R CN VII
               L dysmetria,           (LMN), quadriparesis,
               gait ataxia (dll)      hyperreflexia (dll)

Antibiotics    RHZE (d5)
prior to

Treatment      AMP (dll)              ACV, CRO, DXM (dll);
                                      AMP (dl2); GEN (dl4)

Nadir          dl3

Outcome        Alive, residual        Death (d!8)
               facial numbness,
               mild gait
               ataxia (d33)


               5                          6

Geographical   Villiersdorp,              Atlantis,
location       W Cape                     W Cape

Age            25                         32

Gender         M                          F

Comorbid       None                       None

Length of      7                          7

Symptoms       HA, dizziness;             HA; dizziness,
(in order      R facial palsy,            gait ataxia (d7);
of onset)      N&V (d7)                   L facial numbness,
                                          R facial palsy
                                          (dl5); D/V, N&V

Signs (in      Fever, meningism, R        R CN VI, R CN VII,
order of       CN VII (LMN) (d7);         L CN X, L hemisensory,
onset)         drowsiness, vertigo,       bilat leg dysmetria
               hiccups, L gaze palsy, R   (dl5), R hemiplegia
               hemisensory (dl7)          (d35)

prior to

Treatment      CRO (dl4); DXM (dl7);      MP (d 15); CRO,
               AMP (d20)                  TMP/SXT, MTZ,
                                          AMP (d35)

Nadir          d20                        d35

Outcome        Alive, residual mild       Alive, no focal
               R facial palsy, L gaze     signs (d72)
               palsy (d60)

PE = Port Elizabeth; E Cape = Eastern Cape Province, South
Africa; W Cape = Western Cape Province; F = female; M = male; Hpt
= hypertension; DM = diabetes mellitus; RA = rheumatoid
arthritis; CN = cranial nerve; S = sensory; L = left; R = right;
bilat = bilateral; unilat = unilateral; LMN = lower motor neuron;
nystag = nystagmus; HA = headache; N&V = nausea and vomiting D/V
= double vision; d = days since illness onset; TEL =
telithromycin; MXF = moxifloxacin; AMX = amoxicillin; CRO =
ceftriaxone; RHZE = rifampicin, isoniazid, pyrazinamide,
ethambutol; MP = methylprednisolone; AMP = ampiciUin; ACV =
acyclovir; DXM = dexamethasone; GEN = gentamycin; TMP/SXT =
trimethoprim/sulfamethoxazole; MTZ = metronidazole.

* Not on combination antiretroviral therapy.

Table 2. Laboratory, pathology and radiological investigations


                       1                  2

Inflammatory markers
  WCC                  13                 13.07
  CRP                  ND                 97
  Cells (PMN, Ly, E)   4, 0, 0            11, 484, 5
  Protein (g/L)        0.3                0.8
  Glucose (mmol/L)     6.3                6
L. monocytogenes
  Blood                Pos(d15)           Neg (x 2)
  CSF                  Pos(d17)           Neg
  Brain biopsy         Pos                ND
CT                     ND                 N

  Distribution         L Po, MCP,         L cerebral ped,
    of high              and Cb             L MCP, L Cb
    signal on

  Enhancement          Subtle,            Complete ring
    pattern on T1WI      incomplete
    pre-/post            ring dorsal Po
CN enhancement         N                  Y
Radiological           Demyelination      Abscess
  differential           (BS/ADEM),
  reported               glioma


                       3                4

Inflammatory markers
  WCC                  6.52             12.17
  CRP                  86               85
  Cells (PMN, Ly, E)   66, 21, 6        12, 68, 9
  Protein (g/L)        0.69             0.5
  Glucose (mmol/L)     3.2              2.8
L. monocytogenes
  Blood                Neg (x 2)        Pos (x 2)
  CSF                  Neg              ND
  Brain biopsy         ND               ND
CT                     Well-defined     Poorly defined
                         ring lesions     lesions
                         dorsal Po,       R Po, R MCP;
                         L MCP3           incomplete
  Distribution         ND               R cerebral ped,
    of high                               R MCP, Me,
    signal on                             upper cord

  Enhancement          ND               Incomplete
    pattern on T1WI                     ring
CN enhancement         Y                Y
Radiological           Tuberculoma,     Demyelination
  differential           listerial        (ADEM)
  reported               abscess


                       5                 6

Inflammatory markers
  WCC                  15.31             9.57
  CRP                  ND                ND
  Cells (PMN, Ly, E)   4, 375, 0         0, 60, 0
  Protein (g/L)        0.59              0.63
  Glucose (mmol/L)     3.3               3.3
L. monocytogenes
  Blood                Neg (x 2)         Neg (x 2)
  CSF                  Neg               Neg
  Brain biopsy         ND                ND
CT                     N                 N

  Distribution         R cerebral ped,   Mb, dorsal Po,
    of high              R MCP, dorsal     Cb vermis,
    signal on            Po, Me, upper     Me; after 9 d
  T2WI & FLAIR           cord              interval:
    sequences                              new lesions
                                           L thalamic,
                                           L parietal
  Enhancement          Patchy,           Patchy,
    pattern on T1WI    nodular             nodular;
    pre-/post                              complete ring
CN enhancement         N                 N
Radiological           Demyelination     Abscess,
  differential           (ADEM)            demyelination

WCC = white cell count; CRP = C-reactive protein; CSF =
cerebrospinal fluid; PMN = polymorphonuclear cell; Ly =
lymphocyte; E = erythrocyte; CT = computed tomography; MRI =
magnetic resonance imaging; T2WI = T2-weighted imaging; FLAIR =
fluid attenuated inversion recovery; Pos = positive; Neg =
negative; d = days since symptom onset; ND = not done; N =
normal; L = left; R = right; Mb = midbrain; Po = pons; MCP =
middle cerebellar peduncle; Cb = cerebellum; Me = medulla; ped =
peduncle; CN = cranial nerve; N = no; Y = yes; BS = Bickerstaff
encephalitis; ADEM = acute disseminated encephalomyelitis.
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Article Details
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Title Annotation:CLINICAL ALERT
Author:Fredericks, P.; Britz, M.; Eastman, R.; Carr, J.A.; Bateman, K.J.
Publication:South African Medical Journal
Article Type:Report
Geographic Code:6SOUT
Date:Jan 1, 2015
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