Neurol Sci DOI 10.1007/s10072-014-1691-y
ORIGINAL ARTICLE
Twelve-year monitoring of a patient with megalencephalic leukoencephalopathy with subcortical cysts Francesca Rossi • Marco Battaglini • Maria Laura Stromillo • Antonio Giorgio Antonio Federico • Nicola De Stefano
•
Received: 6 November 2013 / Accepted: 14 February 2014 Ó Springer-Verlag Italia 2014
Abstract Megalencephalic leukoencephalopathy (MLC) with subcortical cysts is an infantile-onset inherited disease of the brain white matter with a defect in brain ion and water homoeostasis, which leads to an abnormal brain volume regulation. Clinical features of the disease can be variable, but patients typically show early-onset macrocephaly, motor abnormalities, seizures, and almost constant late-onset mild mental deterioration. Brain magnetic resonance imaging (MRI) reveals diffusely abnormal and mildly swollen white matter as well as subcortical cysts in the anterior temporal and frontoparietal regions. We describe here clinical findings and volumetric MRI and 1HMR spectroscopic imaging (1H-MRSI) data of a 12-year follow-up on a patient with MLC. The patient had only slight clinical worsening during the long follow-up. Volumetric findings showed substantially unchanged cystic volumes and mild brain atrophy rate. In addition, there was no over time increase in the volume of white matter
F. Rossi M. Battaglini M. L. Stromillo A. Giorgio A. Federico N. De Stefano (&) Department of Medicine, Surgery and Neuroscience, University of Siena, Policlinico ‘‘S. Maria alle Scotte’’, Viale Bracci, 2, 53100 Siena, Italy e-mail: [email protected] F. Rossi e-mail: [email protected] M. Battaglini e-mail: [email protected] M. L. Stromillo e-mail: [email protected] A. Giorgio e-mail: [email protected] A. Federico e-mail: [email protected]
hypointense lesions seen on FLAIR images at baseline, but the degree of hypointensity of these white matter voxels increased over 12 years. Longitudinal 1H-MRSI examination showed long-term undetectable metabolite signals in the white matter, whereas the metabolic pattern of gray matter voxels remained unchanged over time. Results show that, in MLC, the chronic brain white matter changes resulting from the brain ion, and water homeostasis can be monitored by quantitative MRI modalities. This might be important for assessing treatment effects. Keywords Megalencephaly Brain Cysts Leukoencephalopathy White matter Magnetic resonance
Background Megalencephalic leukoencephalopathy (MLC) with subcortical cysts is an infantile-onset inherited disease of the brain white matter (WM) associated with two different genes: MLC1 and HEPACAM (also called GLIALCAM). The most common and classical phenotype has an autosomal recessive mode of inheritance. Classic MLC related to recessive MLC1 mutations has been called MLC1 (MIM number 604004), whereas classic MLC related to recessive HEPACAM mutations has been named MLC2A (MIM number 613925). The remitting MLC or MLC2B refers to patients who initially have a typical clinical picture, but subsequently improve and lack signs of clinical deterioration. This phenotype is related to autosomal dominant mutations in HEPACAM (MIM number 613926) [1]. MLC1 and HEPACAM encode for two proteins (MLC1 and GlialCAM), which colocalize in astrocyte junctions at the endfeet level and have a role in regulating the volume of astrocytes [2].
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Neurol Sci
Clinical features of the disease are the onset of macrocephaly in the first year of life and subsequent development of slowly progressive cerebellar ataxia, spasticity, seizures and mild cognitive deterioration. The clinical course might vary with patients who maintain the ability of walking without support for only short distance and others who still walk without support in their 40s and have no mental deterioration and borderline macrocephaly [2]. Conventional magnetic resonance imaging (MRI) shows diffuse cerebral WM abnormalities with swelling of the Table 1 Volumetric MRI data of the megalencephalic leukoencephalopathy with subcortical cysts (MLC) patient NBV (cm3)
Hyperintense NWMV (cm3)
Hypointense NWMV (cm3)
Cyst volume (right and left) (cm3)
Baseline
1393
355
62.7
0.29 and 4.53
After 6 years
1341
338
62.4
0.29 and 4.70
After 12 years
1308
335
63.1
0.31 and 4.70
NBV normalized brain volume, NWMV normalized white matter volume
Fig. 1 Conventional FLAIR images in axial orientation of the MLC patient at baseline (1, left) and after 6 (2, middle) and 12 years (3, right) showing no increase in the volume of the cysts in the temporal
123
abnormal WM. These WM abnormalities might appear hypointense on fluid attenuated inversion recovery (FLAIR) images due to the high water content. Subcortical cysts may be present, more often in the anterior temporal region and also in the frontal and parietal regions. Cortical and subcortical gray matter (GM) structures are usually preserved [3]. On proton MR spectroscopy (1H-MRS) of severely affected WM, metabolite resonance intensities are usually all decreased and might even become undetectable [4], likely expression of the high water content due to the defect in brain ion and water homoeostasis. The abnormal cerebral WM may become less severely swollen and atrophic over the years, while the subcortical cysts may become larger and more numerous [3]. We report here the volumetric MRI and 1H-MRS imaging (1H-MRSI) findings of a 12-year follow-up of a patient with the classical form of MLC. Clinical and MRI findings of the patient at presentation and after a short follow-up were described previously [5]. We aimed here to assess whether brain changes occurring in the long term in a patient with MLC could be monitored by means of quantitative MRI modalities and could be clinically relevant.
tips. Contour of the cysts is segmented in red. Volumes are reported in Table 1 (color figure online)
Neurol Sci
Case presentation Methods Patient presentation The patient clinical history was previously described [5]. Briefly, he showed an increased head growth before 1 year of age as the first sign of disease and developed mild ataxia at 3 years and seizures at 7 years. The patient lost his ability to walk at 11. At the age of 20, he underwent for the
first time an MRI scan which showed diffuse swelling and abnormalities in the WM, and cysts in the temporal tips. The diagnosis of MLC was proven by the presence of a MLC1 mutation (IVS5 ? 1G [ A/IVS10-1G [ Cà) [6]. Since our first assessment, the patient has been clinically monitored every year for 12 years (he is currently 40 years old). He underwent neuropsychological evaluation by WAIS in 2000 and 2012, and combined MRI and 1H-MRSI examinations at first evaluation and in several other occasions during the 12-year follow-up. We report here conventional and 1H-MRSI data at baseline and after 6 and 12 years. Conventional MRI and 1H-MRSI examinations and analyses
Fig. 2 In the top panel, FLAIR images in axial orientation at baseline and after 12-year follow-up illustrating the white matter abnormalities with hyperintense and hypointense voxels. Note that the hypointense regions within the hyperintense lesions do not show substantial changes over time. In the bottom panel, color maps were created at each time point by normalizing the voxel intensity of the FLAIR image by the averaged intensity of a region of interest selected from the parieto-occipital cortex. The color bar indicates the scale of this intensity ratio. Note the over time decrease of this ratio, which appears very pronounced within the hypointense lesions. As expected, the overall intensity of gray matter does not show any relevant change over time (color figure online)
Combined conventional MRI and 1H-MRSI examinations were acquired in a single session using a Philips Gyroscan operating at 1.5 T (Philips Medical Systems, Best, The Netherlands) as previously described [5]. Briefly, a sagittal survey image was used to identify the anterior commissure (AC) and posterior commissure (PC). Then dual-echo, FLAIR and T1-weighted gradient-echo sequences (50 slices, 3-mm thickness) were acquired in the transverse plane parallel to the AC–PC line. These images were used to select an intracranial volume of interest (VOI) for spectroscopy, measuring approximately 100 mm antero-posterior 9 100 mm left–right 9 20 mm cranio-caudal. In each scan, this was centered on the corpus callosum to include the central brain WM of both hemispheres. Twodimensional spectroscopic images were obtained using a 90°–180°–180° pulse sequence (TR = 2,000 ms, TE = 272 ms, 250-mm field of view, 32 9 32 phaseencoding steps, 1 signal average per step) [7]. The MRI acquisition protocol was identical in the three scans. Periodical quality assurance sessions and no major hardware upgrades were carried out on the scanner during the time of the study. Post-processing of the raw 1H-MRSI data was performed as previously described [7]. Briefly, resonance intensity values of N-acetyl groups [mainly N-Acetyl-
Table 2 1H-MRSI findings in the MLC patient FWM Naa/Cr
Cho/Cr
PWM Naa/Cr
Cho/Cr
CGM Naa/Cr
Cho/Cr
Baseline
2.5
1.4
1.4
1.5
2.7
0.9
After 6 years
1.9
1.8
1.9
1.2
2.6
0.9
After 12 years
1.7
1.6
n.d.
n.d.
2.7
1.0
Normal valuesa
3.1 ± 0.23
1.6 ± 0.18
3.0 ± 0.21
1.3 ± 0.15
2.5 ± 0.14
1.0 ± 0.10
See text for other abbreviations FWM frontal white matter, PWM posterior white matter, CGM cortical gray matter a
Normal values as reported in De Stefano et al. [5]
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Neurol Sci
Aspartate (NAA)], choline (Cho) and creatine (Cr) were determined. In this VOI, we also selectively assessed metabolic values of voxels located in frontal WM (FWM), posterior WM (PWM) and inter-hemispheric GM of the occipito-parietal cortex (CGM). For each 1H-MRSI scan, voxels of this region were selected from both hemispheres and then averaged to determine the mean intensity for each metabolite. In addition to 1H-MRSI measures, the hyperintense WM volume (WMV), the volume of the hypointense regions present within the abnormally hyperintense WM and the volume of the cysts were computed on FLAIR images by employing a semi-automated segmentation technique based on user-supervised local thresholding (Jim 5.0, Xinapse System, Leicester, UK). Further, in the three MRI scans, the degree of hypointensity of WM voxels was measured by simply normalizing each hypointense voxel for the mean intensity of CGM regions in the same slice. Finally, normalized (for head size) brain volume (NBV) and percent brain volume change (PBVC) were measured over the study period using the SIENAX/SIENA softwares, parts of FSL [8].
Fig. 3 The top panel shows the 1 H-MRSI spectra of the MLC patient from voxels located in the frontal white matter (FWM, first row), posterior white matter (PWM, second row) and cortical gray matter (CGM, third row) of both hemispheres at baseline (first column) and after 6 years (second column) and 12 years (third column). In the lower panel, conventional FLAIR images in axial orientation of the MLC patients at the three time points, showing the spectroscopic voxels located in the white and gray matter. Note the progressive loss of metabolite signals in white matter voxels over the years
123
Results Clinical status During the 12-year follow-up the patient, who had been wheelchair-bound for many years, showed a slight worsening of dysarthria and dysmetria. He continued to have one or two seizures per year, particularly after sleep deprivation. The mental status, as evaluated when the patient was 28 years old, showed a moderate impairment: verbal IQ was 58 and performance IQ was 48. After 12 years, this moderate impairment remained substantially unchanged: verbal IQ was 55 and performance IQ was 59. Volumetric MRI findings Over 12-year follow-up, there was a small decrease of the hyperintense WMV (-20 cm3, see Table 1), without significant changes of both hypointense WMV and subcortical cyst volume (see Fig. 1). Despite the absence of significant changes in the hypointense WMV on FLAIR images, the degree of hypointensity in the WM voxels was increased
Neurol Sci
by up to 50 % over 12 years (see Fig. 2). Finally, over 12 years values of NBV showed a slight decrease (-85 cm3, see Table 1) with a PBVC of -6 %. 1
H-MRSI findings
We selected voxels located in FWM, PWM and CGM. 1HMRSI values, expressed as relative to Cr resonance intensity, are summarized in Table 2. Metabolite resonance intensity values of the WM regions largely decreased after the first scan, becoming undetectable at the 12-year followup scan (see Table 2; Fig. 3). By contrast, metabolite resonance intensities in the CGM were within the normal limits at baseline and did not show significant changes over time (see Table 2; Fig. 3).
Conclusion Conventional MRI features of MLC include diffuse cerebral WM abnormalities with swelling of the abnormal WM, subcortical cysts and WM regions that might appear hypointense on FLAIR images due to their very high water content. Over time, the abnormal cerebral WM usually becomes less severely swollen and atrophic, while the subcortical cysts can increase in volume and number. This trend was only partly seen in our long-term follow-up study. Indeed, volumetric findings showed mild brain atrophy rate over 12 years (in the order of *0.5 % per year), with a proportional small decrease in the volume of hyperintense WM voxels and a stability of the cystic volumes. This suggests that brain changes in MLC may progress very slowly even in adulthood, particularly if the patient is clinically stable. Despite no significant changes over time in the volume of WM hypointense lesions seen on FLAIR images at baseline, the degree of hypointensity in these WM voxels appeared to increase by up to 50 % in the 12-year followup (see Fig. 2). Interestingly, this progressed in parallel with the over time decreases in all metabolite signals as detected by 1H-MRSI, which became undetectable in hypointense WM voxels at the 12-year scan. Both the increase of the hypointensity degree of the WM voxels and the absence of detectable signals of brain metabolites can be interpreted as the expression of a defect in brain ion and water homoeostasis occurring in this disease. This leads to an abnormal volume regulation and the consequent brain WM oedema with accumulation of water in vacuoles between myelin lamellae and astrocytic endfeet [2]. By contrast, metabolite resonance intensities in the GM were unchanged and remained unchanged in the long term, providing further evidence that the progressive brain metabolic damage does not involve the neocortex.
In spite of the limitations of a single-subject report, results of our long-term study provide compelling evidence that the chronic brain WM changes resulting from the brain ion and water homoeostasis defect can be monitored by MRI modalities such as volumetric MRI and 1H-MRSI. This is important since MLC might be suitable for treatment, particularly that aiming at decreasing brain oedema. Conflict of interest I have read the journal’s policy and have the following conflicts: Francesca Rossi has nothing to disclose. Marco Battaglini has nothing to disclose. Maria Laura Stromillo has nothing to disclose. Antonio Giorgio has nothing to disclose. Antonio Federico has nothing to disclose. Nicola De Stefano serves on a scientific advisory board for Merck Serono, has received funding for travel from Teva Pharmaceutical Industries Ltd. and Merck Serono, has received speaker honoraria from Teva Pharmaceutical Industries Ltd., BioMS Medical, Biogen-Dompe´ AG, Bayer Schering Pharma, and Merck Serono, and received research support from the Italian MS Society. Consent Informed written consent was obtained from the subject at the time of each MRI examination.
References 1. Van der Knaap MS, Scheper GC (1993) Megalencephalic leukoencephalopathy with subcortical cysts. In: Pagon RA, Adam MP, Bird TD, Dolan CR, Fong CT, Stephens K (eds) GeneReviews, Seattle, University of Washington, http://www.ncbi.nlm.nih.gov/ books/NBK1116/ 2. van der Knapp MS, Boor I, Este´vez R (2012) Megalencephalic leukoencephalopathy with subcortical cysts: chronic white matter oedema due to a defect in brain ion and water homoestasis. Lancet Neurol 11:973–985 3. van der Knaap MS, Barth PG, Stroink H, van Nieuwenhuizen O, Arts WF, Hoogenraad F (1995) Leukoencephalopathy with swelling and a discrepantly mild clinical course in eight children. Ann Neurol 37:324–334 4. Ben-Zeev B, Gross V, Kushnir T, Shalev R, Hoffman C, Shinar Y, Pras E, Brand N (2001) Vacuolating megalencephalic leukoencephalopathy in 12 Israeli patients. J Child Neurol 16:93–99 5. De Stefano N, Balestri P, Dotti MT, Grosso S, Mortilla M, Morgese G, Federico A (2001) Severe metabolic abnormalities in the white matter of patients with vacuolating megalencephalic leukoencephalopathy with subcortical cysts. A proton MR spectroscopic imaging study. J Neurol 248(5):403–409 6. Patrono C, Di Giacinto G, Eymard-Pierre E, Santorelli FM, Rodriguez D, De Stefano N, Federico A, Gatti R, Benigno V, Megarbane´ A, Tabarki B, Boespflug-Tanguy O, Bertini E (2003) Genetic heterogeneity of megalencephalic leukoencephalopathy and subcortical cysts. Neurology 61:534–537 7. De Stefano N, Narayanan S, Francis GS, Arnaoutelis R, Tartaglia MC, Antel JP, Matthews PM, Arnold DL (2001) Evidence of axonal damage in the early stages of multiple sclerosis and its relevance to disability. Arch Neurol 58(1):65–70 8. Smith SM, Jenkinson M, Woolrich MW, Beckmann CF, Behrens TE, Johansen-Berg H, Bannister PR, De Luca M, Drobnjak I, Flitney DE, Niazy RK, Saunders J, Vickers J, Zhang Y, De Stefano N, Brady JM, Matthews PM (2004) Advances in functional and structural MR image analysis and implementation as FSL. Neuroimage 23(Suppl 1):S208–S219
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ORIGINAL ARTICLE
Twelve-year monitoring of a patient with megalencephalic leukoencephalopathy with subcortical cysts Francesca Rossi • Marco Battaglini • Maria Laura Stromillo • Antonio Giorgio Antonio Federico • Nicola De Stefano
•
Received: 6 November 2013 / Accepted: 14 February 2014 Ó Springer-Verlag Italia 2014
Abstract Megalencephalic leukoencephalopathy (MLC) with subcortical cysts is an infantile-onset inherited disease of the brain white matter with a defect in brain ion and water homoeostasis, which leads to an abnormal brain volume regulation. Clinical features of the disease can be variable, but patients typically show early-onset macrocephaly, motor abnormalities, seizures, and almost constant late-onset mild mental deterioration. Brain magnetic resonance imaging (MRI) reveals diffusely abnormal and mildly swollen white matter as well as subcortical cysts in the anterior temporal and frontoparietal regions. We describe here clinical findings and volumetric MRI and 1HMR spectroscopic imaging (1H-MRSI) data of a 12-year follow-up on a patient with MLC. The patient had only slight clinical worsening during the long follow-up. Volumetric findings showed substantially unchanged cystic volumes and mild brain atrophy rate. In addition, there was no over time increase in the volume of white matter
F. Rossi M. Battaglini M. L. Stromillo A. Giorgio A. Federico N. De Stefano (&) Department of Medicine, Surgery and Neuroscience, University of Siena, Policlinico ‘‘S. Maria alle Scotte’’, Viale Bracci, 2, 53100 Siena, Italy e-mail: [email protected] F. Rossi e-mail: [email protected] M. Battaglini e-mail: [email protected] M. L. Stromillo e-mail: [email protected] A. Giorgio e-mail: [email protected] A. Federico e-mail: [email protected]
hypointense lesions seen on FLAIR images at baseline, but the degree of hypointensity of these white matter voxels increased over 12 years. Longitudinal 1H-MRSI examination showed long-term undetectable metabolite signals in the white matter, whereas the metabolic pattern of gray matter voxels remained unchanged over time. Results show that, in MLC, the chronic brain white matter changes resulting from the brain ion, and water homeostasis can be monitored by quantitative MRI modalities. This might be important for assessing treatment effects. Keywords Megalencephaly Brain Cysts Leukoencephalopathy White matter Magnetic resonance
Background Megalencephalic leukoencephalopathy (MLC) with subcortical cysts is an infantile-onset inherited disease of the brain white matter (WM) associated with two different genes: MLC1 and HEPACAM (also called GLIALCAM). The most common and classical phenotype has an autosomal recessive mode of inheritance. Classic MLC related to recessive MLC1 mutations has been called MLC1 (MIM number 604004), whereas classic MLC related to recessive HEPACAM mutations has been named MLC2A (MIM number 613925). The remitting MLC or MLC2B refers to patients who initially have a typical clinical picture, but subsequently improve and lack signs of clinical deterioration. This phenotype is related to autosomal dominant mutations in HEPACAM (MIM number 613926) [1]. MLC1 and HEPACAM encode for two proteins (MLC1 and GlialCAM), which colocalize in astrocyte junctions at the endfeet level and have a role in regulating the volume of astrocytes [2].
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Neurol Sci
Clinical features of the disease are the onset of macrocephaly in the first year of life and subsequent development of slowly progressive cerebellar ataxia, spasticity, seizures and mild cognitive deterioration. The clinical course might vary with patients who maintain the ability of walking without support for only short distance and others who still walk without support in their 40s and have no mental deterioration and borderline macrocephaly [2]. Conventional magnetic resonance imaging (MRI) shows diffuse cerebral WM abnormalities with swelling of the Table 1 Volumetric MRI data of the megalencephalic leukoencephalopathy with subcortical cysts (MLC) patient NBV (cm3)
Hyperintense NWMV (cm3)
Hypointense NWMV (cm3)
Cyst volume (right and left) (cm3)
Baseline
1393
355
62.7
0.29 and 4.53
After 6 years
1341
338
62.4
0.29 and 4.70
After 12 years
1308
335
63.1
0.31 and 4.70
NBV normalized brain volume, NWMV normalized white matter volume
Fig. 1 Conventional FLAIR images in axial orientation of the MLC patient at baseline (1, left) and after 6 (2, middle) and 12 years (3, right) showing no increase in the volume of the cysts in the temporal
123
abnormal WM. These WM abnormalities might appear hypointense on fluid attenuated inversion recovery (FLAIR) images due to the high water content. Subcortical cysts may be present, more often in the anterior temporal region and also in the frontal and parietal regions. Cortical and subcortical gray matter (GM) structures are usually preserved [3]. On proton MR spectroscopy (1H-MRS) of severely affected WM, metabolite resonance intensities are usually all decreased and might even become undetectable [4], likely expression of the high water content due to the defect in brain ion and water homoeostasis. The abnormal cerebral WM may become less severely swollen and atrophic over the years, while the subcortical cysts may become larger and more numerous [3]. We report here the volumetric MRI and 1H-MRS imaging (1H-MRSI) findings of a 12-year follow-up of a patient with the classical form of MLC. Clinical and MRI findings of the patient at presentation and after a short follow-up were described previously [5]. We aimed here to assess whether brain changes occurring in the long term in a patient with MLC could be monitored by means of quantitative MRI modalities and could be clinically relevant.
tips. Contour of the cysts is segmented in red. Volumes are reported in Table 1 (color figure online)
Neurol Sci
Case presentation Methods Patient presentation The patient clinical history was previously described [5]. Briefly, he showed an increased head growth before 1 year of age as the first sign of disease and developed mild ataxia at 3 years and seizures at 7 years. The patient lost his ability to walk at 11. At the age of 20, he underwent for the
first time an MRI scan which showed diffuse swelling and abnormalities in the WM, and cysts in the temporal tips. The diagnosis of MLC was proven by the presence of a MLC1 mutation (IVS5 ? 1G [ A/IVS10-1G [ Cà) [6]. Since our first assessment, the patient has been clinically monitored every year for 12 years (he is currently 40 years old). He underwent neuropsychological evaluation by WAIS in 2000 and 2012, and combined MRI and 1H-MRSI examinations at first evaluation and in several other occasions during the 12-year follow-up. We report here conventional and 1H-MRSI data at baseline and after 6 and 12 years. Conventional MRI and 1H-MRSI examinations and analyses
Fig. 2 In the top panel, FLAIR images in axial orientation at baseline and after 12-year follow-up illustrating the white matter abnormalities with hyperintense and hypointense voxels. Note that the hypointense regions within the hyperintense lesions do not show substantial changes over time. In the bottom panel, color maps were created at each time point by normalizing the voxel intensity of the FLAIR image by the averaged intensity of a region of interest selected from the parieto-occipital cortex. The color bar indicates the scale of this intensity ratio. Note the over time decrease of this ratio, which appears very pronounced within the hypointense lesions. As expected, the overall intensity of gray matter does not show any relevant change over time (color figure online)
Combined conventional MRI and 1H-MRSI examinations were acquired in a single session using a Philips Gyroscan operating at 1.5 T (Philips Medical Systems, Best, The Netherlands) as previously described [5]. Briefly, a sagittal survey image was used to identify the anterior commissure (AC) and posterior commissure (PC). Then dual-echo, FLAIR and T1-weighted gradient-echo sequences (50 slices, 3-mm thickness) were acquired in the transverse plane parallel to the AC–PC line. These images were used to select an intracranial volume of interest (VOI) for spectroscopy, measuring approximately 100 mm antero-posterior 9 100 mm left–right 9 20 mm cranio-caudal. In each scan, this was centered on the corpus callosum to include the central brain WM of both hemispheres. Twodimensional spectroscopic images were obtained using a 90°–180°–180° pulse sequence (TR = 2,000 ms, TE = 272 ms, 250-mm field of view, 32 9 32 phaseencoding steps, 1 signal average per step) [7]. The MRI acquisition protocol was identical in the three scans. Periodical quality assurance sessions and no major hardware upgrades were carried out on the scanner during the time of the study. Post-processing of the raw 1H-MRSI data was performed as previously described [7]. Briefly, resonance intensity values of N-acetyl groups [mainly N-Acetyl-
Table 2 1H-MRSI findings in the MLC patient FWM Naa/Cr
Cho/Cr
PWM Naa/Cr
Cho/Cr
CGM Naa/Cr
Cho/Cr
Baseline
2.5
1.4
1.4
1.5
2.7
0.9
After 6 years
1.9
1.8
1.9
1.2
2.6
0.9
After 12 years
1.7
1.6
n.d.
n.d.
2.7
1.0
Normal valuesa
3.1 ± 0.23
1.6 ± 0.18
3.0 ± 0.21
1.3 ± 0.15
2.5 ± 0.14
1.0 ± 0.10
See text for other abbreviations FWM frontal white matter, PWM posterior white matter, CGM cortical gray matter a
Normal values as reported in De Stefano et al. [5]
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Neurol Sci
Aspartate (NAA)], choline (Cho) and creatine (Cr) were determined. In this VOI, we also selectively assessed metabolic values of voxels located in frontal WM (FWM), posterior WM (PWM) and inter-hemispheric GM of the occipito-parietal cortex (CGM). For each 1H-MRSI scan, voxels of this region were selected from both hemispheres and then averaged to determine the mean intensity for each metabolite. In addition to 1H-MRSI measures, the hyperintense WM volume (WMV), the volume of the hypointense regions present within the abnormally hyperintense WM and the volume of the cysts were computed on FLAIR images by employing a semi-automated segmentation technique based on user-supervised local thresholding (Jim 5.0, Xinapse System, Leicester, UK). Further, in the three MRI scans, the degree of hypointensity of WM voxels was measured by simply normalizing each hypointense voxel for the mean intensity of CGM regions in the same slice. Finally, normalized (for head size) brain volume (NBV) and percent brain volume change (PBVC) were measured over the study period using the SIENAX/SIENA softwares, parts of FSL [8].
Fig. 3 The top panel shows the 1 H-MRSI spectra of the MLC patient from voxels located in the frontal white matter (FWM, first row), posterior white matter (PWM, second row) and cortical gray matter (CGM, third row) of both hemispheres at baseline (first column) and after 6 years (second column) and 12 years (third column). In the lower panel, conventional FLAIR images in axial orientation of the MLC patients at the three time points, showing the spectroscopic voxels located in the white and gray matter. Note the progressive loss of metabolite signals in white matter voxels over the years
123
Results Clinical status During the 12-year follow-up the patient, who had been wheelchair-bound for many years, showed a slight worsening of dysarthria and dysmetria. He continued to have one or two seizures per year, particularly after sleep deprivation. The mental status, as evaluated when the patient was 28 years old, showed a moderate impairment: verbal IQ was 58 and performance IQ was 48. After 12 years, this moderate impairment remained substantially unchanged: verbal IQ was 55 and performance IQ was 59. Volumetric MRI findings Over 12-year follow-up, there was a small decrease of the hyperintense WMV (-20 cm3, see Table 1), without significant changes of both hypointense WMV and subcortical cyst volume (see Fig. 1). Despite the absence of significant changes in the hypointense WMV on FLAIR images, the degree of hypointensity in the WM voxels was increased
Neurol Sci
by up to 50 % over 12 years (see Fig. 2). Finally, over 12 years values of NBV showed a slight decrease (-85 cm3, see Table 1) with a PBVC of -6 %. 1
H-MRSI findings
We selected voxels located in FWM, PWM and CGM. 1HMRSI values, expressed as relative to Cr resonance intensity, are summarized in Table 2. Metabolite resonance intensity values of the WM regions largely decreased after the first scan, becoming undetectable at the 12-year followup scan (see Table 2; Fig. 3). By contrast, metabolite resonance intensities in the CGM were within the normal limits at baseline and did not show significant changes over time (see Table 2; Fig. 3).
Conclusion Conventional MRI features of MLC include diffuse cerebral WM abnormalities with swelling of the abnormal WM, subcortical cysts and WM regions that might appear hypointense on FLAIR images due to their very high water content. Over time, the abnormal cerebral WM usually becomes less severely swollen and atrophic, while the subcortical cysts can increase in volume and number. This trend was only partly seen in our long-term follow-up study. Indeed, volumetric findings showed mild brain atrophy rate over 12 years (in the order of *0.5 % per year), with a proportional small decrease in the volume of hyperintense WM voxels and a stability of the cystic volumes. This suggests that brain changes in MLC may progress very slowly even in adulthood, particularly if the patient is clinically stable. Despite no significant changes over time in the volume of WM hypointense lesions seen on FLAIR images at baseline, the degree of hypointensity in these WM voxels appeared to increase by up to 50 % in the 12-year followup (see Fig. 2). Interestingly, this progressed in parallel with the over time decreases in all metabolite signals as detected by 1H-MRSI, which became undetectable in hypointense WM voxels at the 12-year scan. Both the increase of the hypointensity degree of the WM voxels and the absence of detectable signals of brain metabolites can be interpreted as the expression of a defect in brain ion and water homoeostasis occurring in this disease. This leads to an abnormal volume regulation and the consequent brain WM oedema with accumulation of water in vacuoles between myelin lamellae and astrocytic endfeet [2]. By contrast, metabolite resonance intensities in the GM were unchanged and remained unchanged in the long term, providing further evidence that the progressive brain metabolic damage does not involve the neocortex.
In spite of the limitations of a single-subject report, results of our long-term study provide compelling evidence that the chronic brain WM changes resulting from the brain ion and water homoeostasis defect can be monitored by MRI modalities such as volumetric MRI and 1H-MRSI. This is important since MLC might be suitable for treatment, particularly that aiming at decreasing brain oedema. Conflict of interest I have read the journal’s policy and have the following conflicts: Francesca Rossi has nothing to disclose. Marco Battaglini has nothing to disclose. Maria Laura Stromillo has nothing to disclose. Antonio Giorgio has nothing to disclose. Antonio Federico has nothing to disclose. Nicola De Stefano serves on a scientific advisory board for Merck Serono, has received funding for travel from Teva Pharmaceutical Industries Ltd. and Merck Serono, has received speaker honoraria from Teva Pharmaceutical Industries Ltd., BioMS Medical, Biogen-Dompe´ AG, Bayer Schering Pharma, and Merck Serono, and received research support from the Italian MS Society. Consent Informed written consent was obtained from the subject at the time of each MRI examination.
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