Neuroradiology (2004) 46: 26–30 DOI 10.1007/s00234-002-0851-6

A. Ustymowicz E. Taraso´w J. Zajkowska J. Walecki T. Hermanowska-Szpakowicz

Received: 11 February 2002 Accepted: 18 July 2002 Published online: 9 December 2003
Springer-Verlag 2003

A. Ustymowicz (&) M.C. Sklodowskiej 24 A, 15-276 Bialystok, Poland E-mail: [email protected] Tel.: +48-85-7468218 Fax: +48-85-7468821 A. Ustymowicz Æ E. Taraso´w J. Walecki Department of Radiology, Medical Academy, Bialystok, Poland J. Zajkowska Æ T. Hermanowska-Szpakowicz Department of Infectious Diseases and Neuroinfections, Medical Academy, Bialystok, Poland

DIAGNOSTIC NEURORADIOLOGY

Proton MR spectroscopy in neuroborreliosis: a preliminary study

Abstract We report results of a magnetic resonance spectroscopy (MRS) study in 12 patients with neuroborreliosis. We used a PRESS sequence, placing an 8 cm3 voxel in normal-appearing white matter of the frontal lobe. Peaks indicating N-acetylaspartate (NAA), choline (Cho), creatine (Cr), myo-inositol (mI), lipids (Lip) and lactate (Lac) were identified and ratios of NAA/ Cr, Cho/Cr, mI/Cr, Lip/Cr, Lac/Cr calculated. Significant increases in Cho/Cr and Lip/Cr were noted. No abnormality was found in mean NAA/Cr and Lac/Cr, but in four patients there was a decreased NAA peak; mI/Cr ratio was slightly increased. Although the spectroscopic

Introduction Since 1981, when Willy Burgdorfer discovered the agent of Lyme disease, borreliosis has been commonly recognised as an infection of the nervous system. Diagnosis of neuroborreliosis is based on clinical features and serology [1]. Morphological changes on CT or MRI are infrequent and nonspecific [2, 3, 4, 5]. There have been many reports of investigating different nervous system disorders using magnetic resonance spectroscopy (MRS) [6, 7, 8, 9]. The data obtained with this technique from living tissue are unique because they provide information about metabolic disturbances. MRS may detect changes while MRI fails to reveal any abnormality [8, 10, 11, 12]. Our aim was to look at metabolic parameters with 1H MRS in patients with neuroborreliosis. To our

profile in patients with neuroborreliosis seems to be nonspecific, MRS might be useful for assessing tissue damage of the central nervous system. Keywords Lyme disease Æ Magnetic resonance spectroscopy

knowledge the spectral pattern of Lyme disease has not been described.

Materials and methods We studied 12 patients (eight women and four men, mean age 49 years, range 27–69 years) with clinical evidence of neuroborreliosis and positive immunoserology. A control group consisted of 32 healthy subjects (20 women and 12 men, mean age 45 years, range 22–60 years). All patients underwent a neurological examination. Routine studies including glucose, creatine, antinuclear antigen, rheumatoid factor and liver function tests were performed to exclude other potential causes of neurological disease. Alcoholic subjects and those with a history of high blood pressure were excluded. Antibodies to a Borrelia burgdorferi were measured in serum and cerebrospinal fluid. Patients were examined before initiation of specific treatment. The study protocol was approved by our Ethics Committee and informed consent was obtained from all subjects prior to examination.

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MRI and MRS were performed at 1.5 tesla, with a standard circularly polarised head coil. We obtained 5-mm sections: T1-weighted images before and after intravenous contrast medium (Magnevist 0.1 mmol/kg), TR 300 TE 4.5 ms, flip angle 80 degrees, 5mm-thick sections, and fast spin-echo T2-weighted images, TR 5000 TE 127.6 ms, flip angle 90 degrees, and fluid-attenuated inversion recovery (FLAIR) images, TR 6000 TE 120 ms, flip angle 90 degrees. MRI was obtained at least 24 h before MRS to avoid distortion of the magnetic field due to paramagnetic properties of the contrast medium. 1H MRS was performed with a single-voxel PRESS sequence, TR 1500 TE 35 ms, 192 excitations and 2 kHz bandwidth. A 2·2·2 cm voxel was positioned over normal-appearing white matter (NAWM) of the frontal lobe, on the localising T1-weighted sections. Signal from the voxel of interest was shimmed to within a line width of 3–7 Hz and transmitter pulse power was optimised by automated procedures. The MOIST method was used for suppressing the signal from water. Spectroscopic data were analysed using the software package Via 2.0C provided by the manufacturer. The 1H MRS data were zero-filled to 4096 points. Residual water resonances were removed using time-domain high-pass filtering. Exponential to Gaussian transformation was applied as a time-domain apodising filter. Then the data were Fourier-transformed and phase-corrected. After application of a Legendre polynominal function to approximate the baseline, automated curve fitting was performed using an iterative, nonlinear-least-squares fitting procedure by means of the Levenberg-Marquardt algorithm. Line shapes of simulated peaks used in the fitting process were fixed with 85% Gaussian and 15% Lorentzian fractions. Level of N-acetylaspartate (NAA), choline (Cho), creatine (Cr), myo-inositol (mI), lipids (Lip) and lactate (Lac) were assessed and data were expressed using the Cr signal as an internal reference. A Student
s t -test for unpaired samples was performed between the two groups. A P value of <0.05 was taken as significant.

Results The patients were examined at about 6 weeks–6 years (mean 2.6 years) after the onset of Lyme disease. In four cases it was impossible to date the time of infection: one patient could not remember exposure to ticks, while the others had been bitten many times. The neurological symptoms and signs included headache, nausea, disturbance of memory, sleep or concentration, peripheral and cranial nerve palsies and root pain (Table 1). There was also evidence of involvement of other systems: arthralgia in four cases, myalgia in three, and cardiac problems in one. In eight patients skin lesions had been observed; Table 1 Neurological symptoms and signs in 12 patients with neuroborreliosis Symptoms and signs Headache Nausea Memory disturbance Disturbed concentration Sleep disturbance Peripheral nerve palsies Cranial nerves palsies Root pain

Patients (%) 11 (92%) 4 (33%) 6 (50%) 6 (50%) 4 (33%) 2 (17%) 3 (25%) 5 (42%)

seven had erythema migrans and one acrodermatitis chronicum atrophicans. Serology for neuroborreliosis was positive in all patients. Abnormalities on MRI were observed in seven patients (58%), all of whom had cortical and subcortical atrophy. In four, foci of increased signal in white matter were seen on T2-weighted images: single in one, multiple in three, periventricular in two and subcortical in the other two; one had confluent white-matter lesions. None showed contrast enhancement. All MRS examinations yielded high-quality spectra (Fig 1). Metabolite data are presented in. A significant increase in Cho/Cr and Lip/Cr was found in the patients (P <0.001) (Table 2). Lactate/Cr and NAA/Cr ratios were similar to those of the control group, but four patients had NAA/Cr >1 SD below the mean. These individuals also had abnormal MRI, showing atrophy in all four and white-matter lesions in three. Mean mI/Cr was slightly higher than in healthy subjects, but this did not reach statistical significance (P >0.05).

Discussion Borreliosis, a tick-transmitted infection, may affect the central or peripheral nervous system. It is endemic in the United States, European countries—mainly middle Europe, Scandinavia and Asia [1]. The disease occurs in stages with remissions and exacerbations and different clinical symptoms. Neurological manifestations include meningitis, encephalitis, cranial and peripheral nerves palsies, myelitis, radiculoneuritis and encephalopathy [1, 13, 14, 15]. The limitations of current diagnostic methods often make it difficult to determine whether particular disorders are due to Borrelia burgdorferi infection [16]. Abnormalities are rarely detected with CT or MRI in the course of Lyme disease. Ferna´ndez et al. [5], using MRI found central nervous system changes in 43% of patients with neuroborreliosis . They identified areas of abnormal signal within the cerebral white matter and brain stem. Logigian et al. [14] described focal lesions in Lyme encephalopathy in 20–30% of patients. We demonstrated similar areas of increased intensity in four patients (30%) and atrophy in seven (58%). MRS has been applied to many inflammatory and infectious brain disorders. Altered metabolite levels have been reported in bacterial abscesses, intracranial tuberculomas, Creutzfeldt-Jakob disease, herpes simplex encephalitis, Rasmussen
s encephalitis, and HCV and HIV infection [6, 11, 17, 18]. This is the first study applying MRS to neuroborreliosis. In normal-appearing white matter of the frontal lobes we observed increases in Cho/Cr and Lip/Cr. A reduced NAA/Cr ratio was seen in four patients with abnormal MRI. Similar metabolite changes were

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Fig. 1 a, b 1H MR spectra. a A healthy subject b a patient with neuroborreliosis

Table 2 Metabolite ratios in 12 patients and 32 control subjects Metabolite ratio N-acetylaspartate/creatine(Cr) Choline/Cr Myo-inositol/Cr Lipids/Cr Lactate/Cr a

Patients 1.85±0.28 1.00±0.17 a 0.69±0.30 1.64±1.46 a 0.10±0.16

Control subjects 1.84±0.29 0.79±0.13 0.62±0.18 0.62±0.41 0.09±0.08

P <0.001

detected in normal-appearing white matter in patients with optic neuritis [8]. The main abnormalities consisted of a decrease in NAA, an increase in Cho at long, and the presence of free Lip peaks at short echo times. Forton et al. [11] reported increased Cho/Cr and

normal NAA/Cr in normal-appearing white matter in patients with mild, chronic HCV infection, without hepatic encephalopathy. They suggest that infection of cerebral microglia, possibly via infected monocytes, and subsequent microglia activation, underlay the MRS changes. An abnormal level of Cho has also been observed in normal-appearing white matter in HIV-positive patients in the early stages of infection, while a significant reduction in NAA was found in those with advanced dementia [19]. Pathological examinations of these subjects show astroglia and microglial proliferation, with or without neuronal disintegration, the subcortical white matter [20]. Raised Cho and slightly increased mI peaks were reported by Sener [18] in Rasmussen
s encephalitis. He

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also reported NAA reduction, probably reflecting neuronal loss or dysfunction in the involved areas. The metabolic changes we observed in a group of patients with neuroborreliosis may represent persistent an inflammatory process with neuronal damage. Slightly increased mI probably reflects increased gliosis late in the disease. The abnormalities detected could also suggest demyelination. An increase in Cho and Lip and the presence of Lac have been demonstrated in active multiple sclerosis (MS) plaques, while inactive lesions showed NAA reduction [21]. Some groups reported MRS changes in normal-appearing white matter in MS [12, 22, 23]. Falini et al. [23] noted a trend toward an increase in Cho/Cr and mI/Cr and a decrease in NAA/ Cho. The MRS changes reported here probably reflect a variety of microscopic pictures. In histopathological reports of neuroborreliosis, a variety in degree and site of the pathological changes is recognised. Examinations of autopsy cases of chronic neuroborreliosis revealed lymphocytic infiltrates, proliferation of activated microglia,

spongiform tissue changes, neuronal deficit and astrogliosis [24]. Diffuse, moderate microglial proliferation in both the white and grey matter, with elongated forms and fine microglial nodules and diffuse astrogliosis were reported by Bertrand et al. [25]. They also described multiple small areas of complete demyelination scattered in the central white matter of the cerebral and cerebellar hemispheres, and diffuse inflammatory infiltrates, composed predominantly of lymphocytes. Although the spectroscopic profile in patients with neuroborreliosis seems not to be specific, MRS might conceivably influence therapeutic choices and treatment monitoring, by assessing the condition and progression of pathologic processes. Our findings imply that treatment should be directed not only against inflammation, but in some cases also towards axonal protection. This is a report of a preliminary study. Further examinations, in a larger group, are necessary. It will probably be interesting to compare patients in the early and later stages of the disease, as well as before and after treatment.

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