Periventricular White Matter Signal Research Articles

Clinical analysis in patients with SPG11 hereditary spastic paraplegia.

To analyze the clinical phenotype of hereditary spastic paraplegia (HSP) caused by SPG11 mutations (SPG11-HSP). Among the 17 patients with sporadic HSP who performed whole exome sequencing analysis, six were diagnosed with SPG11-HSP. The clinical and radiologic findings and the results of the electrodiagnostic and neuropsychologic tests were reviewed retrospectively. The median age at onset was 16.5 years (range, 13-38 years). Progressive spastic paraparesis was a core feature, and the median spastic paraplegia rating scale score was 24/52 (range, 16-31 points). Additional major symptoms were pseudobulbar dysarthria, intellectual disability, bladder dysfunction, and being overweight. Minor symptoms included upper limbs rigidity and sensory axonopathy. The median body mass index was 26.2 kg/m2 (range, 25.2-32.3 kg/m2). The thin corpus callosum (TCC) was predominant at the rostral body or anterior midbody, and the ears of the lynx sign was seen in all. The follow-up MRI showed the worsening of periventricular white matter (PVWM) signal abnormalities with ventricular widening or the extension of the TCC. Motor evoked potentials (MEP) to the lower limbs showed an absent central motor conduction time (CMCT) in all subjects. The upper limb CMCT was initially absent in three subjects, although it became abnormal in all at the follow-up. The mini-mental state examination median score was 27/30 (range, 26-28) with selective impairment of the attention/calculation domain. The median score of the full-scale intelligence quotient was 48 (range, 42-72) on the Wechsler Adult Intelligence Scale test. Attention/calculation deficits and being overweight as well as pseudobulbar dysarthria were common additional symptoms in patients with SPG11-HSP. The rostral body and anterior midbody of the corpus callosum were preferentially thinned, especially in the early stage of the disease. The TCC, PVWM signal changes, and MEP abnormality worsened as the disease progressed.

Symptomatic care of late-onset Alexander disease presenting with area postrema-like syndrome with prednisolone; a case report

BackgroundAlexander disease (AxD) is classified into AxD type I (infantile) and AxD type II (juvenile and adult form). We aimed to determine the potential genetic cause(s) contributing to the AxD type II manifestations in a 9-year-old male who presented area postrema-like syndrome and his vomiting and weight loss improved after taking prednisolone.Case presentationA normal cognitive 9-year-old boy with persistent nausea, vomiting, and a significant weight loss at the age of 6 years was noticed. He also experienced an episode of status epilepticus with generalized atonic seizures. He showed non-febrile infrequent multifocal motor seizures at the age of 40 days which were treated with phenobarbital. He exhibited normal physical growth and neurologic developmental milestones by the age of six. Occasionally vomiting unrelated to feeding was reported. Upon examination at 9 years, a weak gag reflex, prominent drooling, exaggerated knee-deep tendon reflexes (3+), and nasal tone speech was detected. All gastroenterological, biochemical, and metabolic assessments were normal. Brain magnetic resonance imaging (MRI) revealed bifrontal confluent deep and periventricular white matter signal changes, fine symmetric frontal white matter and bilateral caudate nucleus involvements with garland changes, and a hyperintense tumefactive-like lesion in the brain stem around the floor of the fourth ventricle and area postrema with contrast uptake in post-contrast T1-W images. Latter MRI at the age of 8 years showed enlarged area postrema lesion and bilateral middle cerebellar peduncles and dentate nuclei involvements. Due to clinical and genetic heterogeneities, whole-exome sequencing was performed and the candidate variant was confirmed by Sanger sequencing. A de novo heterozygous mutation, NM_001242376.1:c.262 C > T;R88C in exon 1 of the GFAP (OMIM: 137,780) was verified. Because of persistent vomiting and weight loss of 6.0 kg, prednisolone was prescribed which brought about ceasing vomiting and led to weight gaining of 3.0 kg over the next 3 months after treatment. Occasional attempts to discontinue prednisolone had been resulting in the reappearance of vomiting.ConclusionsThis study broadens the spectrum of symptomatic treatment in leukodystrophies and also shows that R88C mutation may lead to a broad range of phenotypes in AxD type II patients.

A novel deletion variant in CLN3 with highly variable expressivity is responsible for juvenile neuronal ceroid lipofuscinoses.

Mutations in CLN3 (OMIM: 607042) are associated with juvenile neuronal ceroid lipofuscinoses (JNCL)-a rare neurodegenerative disease with early retinal degeneration and progressive neurologic deterioration. The study aimed to determine the underlying genetic factors justifying the NCL phenotype in a large Iraqi consanguineous family. Four affected individuals with an initial diagnosis of NCL were recruited. By doing neuroimaging and also pertinent clinical examinations, e.g. fundus examination, due to heterogeneity of neurodevelopmental disorders, the proband was subjected to the paired-end whole-exome sequencing to identify underlying genetic factors. The candidate variant was also confirmed by Sanger sequencing. Various in silico predictions were used to show the pathogenicity of the variant. This study revealed a novel homozygous frameshift variant-NM_000086.2: c.1127del; p.(Leu376Argfs*15)-in the exon 14 of the CLN3 gene as the most likely disease-causing variant. Three out of 4 patients showed bilateral vision loss (< 7years) and retinal degeneration with macular changes in both eyes. Electroencephalography demonstrated the loss of normal posterior alpha rhythm and also low amplitude multifocal slow waves. Brain magnetic resonance imaging of the patients with a high degree of deterioration showed mild cerebral and cerebellar cortical atrophy, mild ventriculomegaly, thinning of the corpus callosum and vermis, and non-specific periventricular white matter signal changes in the occipital area. The novel biallelic deletion variant of CLN3 was identified that most probably led to JNCL with variable expressivity of the phenotype. This study also expanded our understanding of the clinical and genetic spectrum of JNCL.

Atypical neuroimaging characteristics of hemophagocytic lymphohistiocytosis in infants: a case series of hemorrhagic brain lesions in the deep grey matter

Hemophagocytic lymphohistiocytosis (HLH) is a rare multisystem condition associated with uncontrolled overproduction and infiltration of lymphocytes and histiocytes predominantly in liver, lymph nodes, spleen, and central nervous system. Neuroimaging findings on MRI are fairly nonspecific and classically include periventricular white matter signal abnormalities and diffuse atrophy. Focal parenchymal lesions may demonstrate post contrast ring or nodular enhancement and calcification. However, the MR imaging characteristics can be highly variable. Here, we present two cases of HLH in infants with multiple hemorrhagic lesions mostly depicted in both thalami and basal ganglia regions. Thalamic, basal ganglia, and brain stem involvement with hemorrhagic changes in HLH are rarely described in literature. Early diagnosis of HLH may be lifesaving. Awareness of the disease is necessary to investigate its characteristic findings and avoiding a delay in diagnosis.

Kosaki overgrowth syndrome: A newly identified entity caused by pathogenic variants in platelet-derived growth factor receptor-beta.

Specific classes of de novo heterozygous gain-of-function pathogenic variants of the PDGFRB (platelet-derived growth factor receptor-beta) cause a distinctive overgrowth syndrome, named the Kosaki overgrowth syndrome (KOGS) (OMIM #616592). Until now, six patients with this condition have been reported in the literature. In addition to skeletal overgrowth, these patients exhibit hyperelastic, translucent, and fragile skin, scoliosis, progressive loss of subcutaneous adipose tissue, skull deformity, infantile myofibromas, neuropsychiatric symptoms, and arachnoid cysts in the posterior fossa and periventricular white matter signal abnormalities on neuroimaging. This constellation of phenotypes clearly distinguishes KOGS from other PDGFRB-related disorders, including idiopathic basal ganglia calcification, infantile myofibroma, and Penttinen-type premature aging syndrome. From a molecular standpoint, PDGFRB is a dimeric receptor tyrosine kinase that plays critical roles in cell growth and tumorigenesis. The two known types of pathogenic variants (p.(Pro584Arg) and p.(Trp566Arg)) of the PDGFRB that cause KOGS are exclusively located in the juxtaglomerular domain that regulates autoactivation/inhibition of PDGFRB. In-vitro evidence suggests that p.(Pro584Arg) represents a gain-of-function pathogenic variant. Inhibition of PDGFRB activity using multi-kinase inhibitors appears to be a potentially promising therapeutic approach. Investigation of the molecular mechanisms underlying the pathogenesis of this disease using induced pluripotent stem cells is under way. Presence of skeletal overgrowth, distinctive facial features, characteristic hyperelastic and fragile skin, and cerebral white matter lesions with neuropsychiatric symptoms should prompt genetic analysis of the PDGFRB.

Subacute sclerosing panencephalitis.

Subacute sclerosing panencephalitis (SSPE) is a slowly progressive brain disorder caused by mutant measles virus. SSPE affects younger age groups. SSPE incidence is proportional to that of measles. High-income countries have seen substantial decline in SSPE incidence following universal vaccination against measles. SSPE virus differs from wild measles virus. Measles virus genome recovered from the autopsied brain tissues demonstrates clustered mutations in virus genome particularly in the M gene. These mutations destroy the structure and functioning of the encoded proteins. Complete infectious virus particle has rarely been recovered from the brain. Human neurons lack required receptor for entry of measles virus inside the neurons. Recent in vitro studies suggest that mutations in F protein confer hyperfusogenic properties to measles virus facilitating transneuronal viral spread. The inflammatory response in the brain leads to extensive tissue damage. Clinically, SSPE is characterized by florid panencephalitis. Clinically, SSPE is characterized by cognitive decline, periodic myoclonus, gait abnormalities, vision loss, and ultimately to a vegetative state. Chorioretinitis is a common ocular abnormality. Electroencephalography (EEG) shows characteristic periodic discharges. Neuroimaging demonstrates periventricular white matter signal abnormalities. In advanced stages, there is marked cerebral atrophy. Definitive diagnosis requires demonstration of elevated measles antibody titers in cerebrospinal fluid (CSF). Many drugs have been used to stabilize the course of the disease but without evidence from randomized clinical trials. Six percent of patients may experience prolonged spontaneous remission. Fusion inhibitor peptide may, in the future, be exploited to treat SSPE. A universal vaccination against measles is the only proven way to tackle this menace currently.

Photosensitivity is an early marker of neuronal ceroid lipofuscinosis type 2 disease.

This study aimed to identify early clinical, magnetic resonance imaging (MRI), and electroencephalographic (EEG) characteristics of neuronal ceroid lipofuscinosis type 2 (CLN2) disease to enable early diagnosis, thus providing the key to early treatment, and optimized care and outcomes. Retrospective clinical chart review of a series of patients diagnosed with CLN2 disease from 2005 to 2015 at a single center in Italy. Clinical, MRI, and EEG findings were reviewed. A total of 14 patients were included. For the whole group, median (range) age at disease onset was 3.0 (2.0-3.8) years. Epilepsy was the most commonly reported presenting symptom (in 50% [seven of 14] of patients), occurring at the age of 3.2 (2.6-3.8) years. First seizure was myoclonic in 36% (five of 14) of patients, followed by generalized tonic-clonic in 29% (4 of 14), atonic in 22% (three of 14), and focal with motor signs in 14% (two of 14). All patients walked independently at the age of 12.0 (11.0-18.0) months, but delayed speech or regression of acquired verbal skills was present in 100% of patients at 3 years. EEGs revealed a photoparoxysmal response (PPR) on intermittent photic stimulation in 93% (13 of 14) of patients. PPR was present from the first EEG, which was performed at 3.6 (3.1-4.0) years, in 43% (six of 14) of patients; it was documented at low (1-3 Hz) stimulation frequencies in 69% (nine of 13) and took the form of a flash-per-flash response in 69% (nine of 13). First brain MRI at the age of 3.8 (3.0-5.1) years revealed cerebellar atrophy in 100% (14 of 14) of patients and alteration of the periventricular white matter signal in the posterior hemispheric region in 79% (11 of 14). Early photosensitivity (typically PPR at low stimulation frequencies of 1-3 Hz) is a hallmark of CLN2 disease. This diagnosis should be considered in a child presenting with any type of seizure, and particularly if it is accompanied by delayed speech and/or ataxia or MRI abnormalities (posterior white matter signal alteration or cerebellar atrophy).

MRI and proton spectroscopy in children with late infantile neuronal ceroid lipofuscinosis: Preliminary results

Aim of the study was to characterize findings on magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy ( 1 H-MRS) in children with late infantile neuronal ceroid lipofuscinosis (NCL) and the relationship between these results and duration of the disorder. Three children with late infantile NCL and six age-matched controls were examined with MRI and by localized 1 H-MRS. Voxel regions studied were periventricular frontal white matter, thalami and cerebellar deep white matter. N-acetylaspartate/creatine (NAA/Cr) and choline/creatine (Cho/Cr) ratio was calculated. MRI showed various degrees of cortical atrophy and increased periventricular white matter signal intensity on T2- and -fluid attenuated inversion recovery-weighted images. There was no significant volume loss in the brainstem. Metabolic ratio (NAA/Cr and Cho/Cr) showed progressive decrease with longer disease duration in thalamic and cerebellar voxels and exhibited a negative relationship in frontal voxels. In conclusion, the most significant changes on neuroimaging in late infantile NCL are progressive cortical and cerebellar atrophy, which are more pronounced in the cerebellum. Decreased signal intensity in the thalami may also be observed as in other forms of NCL. 1 H-MRS is the most sensitive method for measuring metabolic changes. The decreased level of NAA although

Hyperhomocysteinemia and MTHFR polymorphisms as antenatal risk factors of white matter abnormalities in two cohorts of late preterm and full term newborns.

Higher total homocysteine (tHcy) levels, and C677T and A1298C methylenetetrahydrofolate (MTHFR) polymorphisms, have been reported in preterm or full term newborns with neonatal encephalopathy following perinatal hypoxic-ischemic insult. This study investigated the causal role of tHcy and MTHFR polymorphisms together with other acquired risk factors on the occurrence of brain white matter abnormalities (WMA) detected by cranial ultrasound scans (cUS) in a population of late preterm and full term infants. A total of 171 newborns (81 M, 47.4%), 45 (26.3%) born <37 wks, and 126 (73.7%) born ≥37 wks were recruited in the study. cUS detected predominant WMA pattern in 36/171 newborns (21.1%) mainly characterized by abnormal periventricular white matter signal and mild-to-moderate periventricular white matter volume loss with ventricular dilatation (6/36, 16.6%). WMA resulted in being depending on tHcy levels (P < 0.014), lower GA (P < 0.000), lower Apgar score at 1 minutes (P < 0.000) and 5 minutes (P < 0.000), and 1298AC and 677CT/1298AC genotypes (P < 0.000 and P < 0.000). In conclusion, both acquired and genetic predisposing antenatal factors were significantly associated with adverse neonatal outcome and WMA. The role of A1298C polymorphism may be taken into account for prenatal assessment and treatment counseling.

Adult-onset leukoencephalopathy with axonal spheroids and pigmented glia: report on a case with morphometric studies

Two previously distinct leukodystrophies, pigmentary orthochromatic leukodystrophy and hereditary diffuse leukoencephalopathy with spheroids, have recently been interpreted as variants of the same disease, adult-onset leukoencephalopathy with spheroids and pigmented glia (ALSP). We report a sporadic case of a 56-year-old male with ALSP presenting as frontotemporal dementia behavioral variant (FTD-bv). He had a history of depression and developed socially inappropriate behaviors consistent with FTD-bv. His first neurological exam was normal, but he developed new symptoms in the next 1.5 years: executive functional difficulties, anosognosia, urinary incontinence, epilepsy, extrapyramidal syndrome, severe gait disturbance, dysarthria, dysphagia and mutism. He died of pneumonia 20 months after initial presentation. MRI revealed increased T2-FLAIR signal in periventricular white matter and corpus callosum atrophy. Histology showed extensive demyelination of the centrum semiovale, most severe in frontal and temporal lobes, sparing U-fibers. There was no cortical neuronal loss, but selective loss of thalamic neurons. Histopathological hallmarks were cortical neuronal ballooning, white matter orthochromasia, pigmented macrophages, oligodendroglial loss, and axonal spheroids, some myelinated and some vacuolated. Morphometric studies for myelin, spheroids, oligodendrocytes and astrocytes showed that: 1) spheroids were most abundant in areas of partial demyelination rather than areas of extensive demyelination, being absent in normal appearing areas, 2) oligodendrocyte loss only occurred in regions of extensive demyelination and not in partial demyelination, and 3) there was no statistically significant change in number of astrocytes. There were also many more spheroids than physiologically expected in the gracile and cuneate nuclei. These findings suggest that the formation of spheroids is an early-stage event in disease progression. *These authors contributed equally to this work.

Hypomyelination and congenital cataract: Identification of novel mutations in two unrelated families

BackgroundHypomyelination and congenital cataract (HCC) is a rare autosomal recessive white matter disorder characterized by congenital cataract, progressive neurologic impairment, and myelin deficiency in the central and peripheral nervous system, caused by mutations in the FAM126A gene. AimsTo report three patients of two unrelated families segregating novel mutations. Methodsclinical, neurophysiological, neuroradiologic and molecular investigations were carried out. ResultsAll patients show bilateral congenital cataract and progressive neurological impairment with peripheral neuropathy. The clinical phenotype is consistent with the severe form of HCC. Brain magnetic resonance imaging show the combination of a diffuse hypomyelination with superimposed periventricular white matter signal abnormalities. Conclusionsthis study describes three additional HCC patients indicating that this recently defined leukoencephalopathy should be included in the differential diagnosis of hypomyelination in childhood. The peculiar clinical and neuroradiologic findings are useful to properly address molecular investigations and allow the differential diagnosis between HCC and other hypomyelinating forms.

Reply: Painful legs and moving toes: Clinical and electrophysiological observations

I read with great interest the article by Alvarez et al.1 In their review, they confirmed that Painful Legs and Moving Toes (PLMT's) etiology is diverse although the majority of patients had evidence of peripheral nerve involvement or radiculopathy. However, in some patients, namely in patients with Wilson's disease2 and myelitis,3 a structural central nervous system lesion is evoked to be associated with the development of PLMT. We reported a patient with Hashimoto's disease4 who developed slight dystonia and bradykinesia and presented PLMT. The patient had any electrophysiological signs of neuropathy or any clinical sign indicative of a root or nerve disorder. MRI brain scan showed several small sub-cortical white matter fronto-parietal lesions, without diffusion restriction. Discrete and diffuse high signal in periventricular white matter was visible in T2-weighted images. These aspects are frequently found in Hashimoto's encephalopathy.5 We also believe that at least in some cases PLMT has a central origin and is composed of a variety of dystonic movements. In our reported case,4 we think PLMT was associated with Hashimoto's encephalopathy. João Guimarães MD*, * British Hospital XXI, Lisboa, Portugal.

Clinical history and new prognostic indicators in metachromatic leukodystrophy

Objective: To study clinical phenotypes and to increase knowledge of natural history of different variants of metachromatic leukodystrophy (MLD). Background: Little is known about factors influencing age of onset, progression rate and peripheral nerve involvement in MLD due to its rarity, heterogeneity and paucity of serial clinical and instrumental reports. Methods: 15 biochemically and molecularly characterized MLD patients were evaluated along a two‐year follow‐up period with clinical, electroneurographic (ENG) and brain MRI recordings. Results: Late infantile patients had a progressive and rapid course, whereas juvenile form showed marked variability. Different clinical presentations were associated with similar levels of ARSA activity; mutation screening indicated a high prevalence of rare or private mutations. In all late infantile and in the adult patient, ENG revealed a severe polyneuropathy. In juvenile patients a milder polyneuropathy or even normal tests were found. The earliest MRI change was periventricular white matter signal alterations, with initial involvement of posterior regions in a majority of late infantile patients, while in juvenile forms white matter lesions were mainly anterior. Conclusions: MLD course is highly variable and only partially influenced by age of onset, especially among juvenile patients. No clear‐cut correlations exist between clinical phenotype and biochemical or molecular characterization. The presence of peripheral neuropathy at onset seems a strong indicator of a poorer clinical outcome.

Regression of HIV encephalopathy and basal ganglia signal intensity abnormality at MR imaging in patients with AIDS after the initiation of protease inhibitor therapy.

To determine whether protease inhibitors cause regression of periventricular white matter signal intensity abnormalities in patients with human immunodeficiency virus (HIV) encephalopathy and whether the changes on magnetic resonance (MR) images correlate with cognitive improvement. MR images were retrospectively and prospectively analyzed in 16 adult patients with HIV encephalopathy. White matter and basal ganglia signal intensity abnormalities on initial long repetition time (TR) images were compared with those on subsequent long TR images in patients who received and in patients who did not receive protease inhibitors. Clinical correlation was obtained. Of the nine patients receiving protease inhibitors, four showed nearly complete regression, four showed interval stability, and one showed slight progression. Thus, eight patients (89%) demonstrated either stability or improvement in white matter disease, which correlated with cognitive improvement. Of the seven patients not receiving protease inhibitors, six (86%) showed marked progression with a decline in cognitive function and one had no interval change. The difference between the two groups was statistically significant. Of the two patients receiving protease inhibitors who initially had basal ganglia signal intensity abnormalities, one demonstrated resolution and one nearly complete resolution subsequently. Although the patient population is small, protease inhibitors may cause regression of periventricular white matter and basal ganglia signal intensity abnormalities in HIV encephalopathy and may have a role in treatment.

Magnetic resonance imaging and behavioral analysis of immature rats with kaolin-induced hydrocephalus: pre- and postshunting observations.

The motor and cognitive dysfunction associated with hydrocephalus remains a clinical problem in children. We hypothesized that young rats with hydrocephalus should exhibit similar dysfunction and that the dysfunction should be reversible by shunting. Hydrocephalus was induced in 3-week-old rats by injection of kaolin into the cisterna magna. Rats were assessed by T2-weighted images obtained with a 7-T magnetic resonance device and by repeated behavioral testing including ability to traverse a narrow beam and ability to find a hidden platform in a water pool. Some of the rats underwent a shunting procedure 1 or 4 weeks after kaolin injection. Magnetic resonance images were used to measure ventricle size. They clearly demonstrated increased signal in periventricular white matter, which corresponded to increased brain water content. A flow-void phenomenon was observed in the cerebral aqueduct. Ability to traverse the beam did not correlate with the degree of ventriculomegaly. Ability to swim to the hidden platform demonstrated a progressive impairment of learning function which may have been accentuated by motor disability. When rats were shunted after 1 week, the behavioral dysfunction was prevented. Late shunting after 4 weeks was associated with gradual recovery of the behavioral disability which was not complete after 4 weeks. We conclude that early shunting is superior to late shunting with regard to behavioral dysfunction. High-resolution MR imaging shows features in hydrocephalic rats similar to those found in hydrocephalic humans.

Central nervous system effects of chronic toluene abuse—Clinical, brainstem evoked response and magnetic resonance imaging studies

We describe the results of neurological evaluation, magnetic resonance imaging (MRI) of the brain and brainstem auditory evoked response (BAER) testing in 11 chronic toluene vapor abusers. Neurological abnormalities were seen in four of 11 individuals and included cognitive, pyramidal, cerebellar and brainstem findings. MRI of the brain was abnormal in three of 11 individuals and revealed the following abnormalities: 1) Diffuse cerebral, cerebellar, and brainstem atrophy; 2) Loss of differentiation between the gray and white matter throughout the CNS; and 3) Increased periventricular white matter signal intensity on T2 weighted images. BAERs were abnormal (control mean ±3 S.D.) in five of 11 individuals. As a group, the latency of V ( p<0.01), the III–V interpeak ( p<0.05) and the I–V interpeak latencies were prolonged compared to controls. All three individuals with abnormal MRI scans also had abnormal neurological examinations and BAERs. Two of five individuals with abnormal BAERs, however, had normal neurological examinations and MRI scans. Our data support previous findings of diffuse white matter involvement in chronic toluene abusers and suggest that BAERs may detect early CNS injury from toluene inhalation even at a time when neurological examination and MRI scans are normal. BAERs, therefore, may be a sensitive screening test to monitor individuals at risk from toluene exposure (either abusers or industrially exposed individuals) for early evidence of CNS injury.

Toluene abuse causes diffuse central nervous system white matter changes

We describe the findings of magnetic resonance imaging (MRI) of the brain in 6 chronic toluene vapor abusers and the neuropathological findings in 1 abuser not studied by MRI. MRI in 6 chronic toluene abusers revealed the following abnormalities: (1) diffuse cerebral, cerebellar, and brainstem atrophy; (2) loss of differentiation between the gray and white matter throughout the central nervous system; and (3) increased periventricular white matter signal intensity on T2-weighted images. Another chronic toluene abuser (MRI not performed) died as a result of acute toluene overdose. The brain displayed diffuse, ill-defined myelin pallor, maximal in cerebellar, periventricular, and deep cerebral white matter. Neurons were preserved throughout, axonal swelling or beading was not seen, gliosis was minimal, and occasional, scant perivascular macrophage collections were seen. Taken in concert, these findings suggest that the pathological and MRI abnormalities are due to either increased water content of the white matter or subtle toluene-induced metabolic changes in myelin.

NMR approach of the periventricular white matter

From a series of 117 neurological patients presenting a pathological periventricular white matter signal on NMR, the authors discuss the differential diagnosis possibilities based on the configuration of the lesions, on their localization in the brain, and on the calculated apparent T2 (T2**) values achieved with the single multi-echos technique.