Peak width of skeletonized mean diffusivity (PSMD) as marker of widespread white matter tissue damage in multiple sclerosis.

BACKGROUND: Peak width of skeletonized mean diffusivity (PSMD) is a novel and fully automated, MRI biomarker, which has shown clinical relevance in cerebral small vessel diseases (SVD). We aimed here to assess PSMD levels across the brain of patients with multiple sclerosis (MS), in comparison to normal controls (NC) and patients with CADASIL, a genetically defined form of severe SVD. METHODS: We assessed PSMD in relapsing-remitting (RR) MS patients (n = 47) in comparison to age-matched CADASIL patients (n = 25) and NC (n = 28). Diffusion Tensor Imaging data were acquired on 1.5T MR clinical scanner to automatically compute PSMD through "skeletonization" of WM tracts and diffusion histograms. RESULTS: RRMS had lower WM lesion volume (LV) than CADASIL (8.6 ±â€¯8.2 vs 24.4 ±â€¯17.4 cm3, p < 0.001). After correction for LV, PSMD values in MS were higher than in CADASIL patients (adjusted mean values: 4.5 vs 3.9 × 10-4 mm2/s, p = 0.03) and in both patient groups were higher than in NC (2.8 ±â€¯0.3 × 10-4 mm2/s, p < 0.001). PSMD values correlated with LV in both patient groups (r = 0.8, p < 0.001 in MS; r = 0.6, p = 0.002 in CADASIL). CONCLUSIONS: In both patient groups, PSMD was higher than in NC and closely correlated with LV, suggesting sensitivity in assessing brain tissue damage in these disorders. In MS patients, PSMD levels were higher than in CADASIL patients, despite the lower LV. This might be related to more severe normal-appearing WM abnormalities occurring in the MS brains. This novel, fully automated, MRI metric may represent a useful marker for a robust quantification of the diffuse WM tissue damage in MS.

AARS2-related ovarioleukodystrophy: Clinical and neuroimaging features of three new cases.

INTRODUCTION: Adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP), previously known as hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS) or pigmentary orthochromatic leukodystrophy (POLD), is the most frequent non-vascular adult-onset leukoencephalopathy. It is caused by autosomal dominant mutations in CSF1R gene. Recently, also autosomal recessive mutations in AARS2 gene were found to be the cause of an adult-onset leukodystrophy with axonal spheroids. Our aim was to achieve a genetic diagnosis in a cohort of CSF1R-negative patients, performing a sequence analysis of AARS2 gene. MATERIAL AND METHODS: AARS2 sequencing was performed in 38 CSF1R-negative patients with clinical and magnetic resonance imaging (MRI) findings of adult-onset leukoencephalopathy. RESULTS: Three patients carrying AARS2 compound heterozygous mutations have been found. All patients were female with ovarian failure and leukoencephalopathy. In 2 patients, MRI findings were consistent with previous reports while the third patient showed focal white matter (WM) lesions in the centrum semiovale and the corpus callosum in the absence of extensive involvement and rarefaction of the WM. MRI spectroscopy showed the presence of increased lactate in 2 patients, thus linking AARS2-related leukoencephalopathy with other mitochondrial leukoencephalopathies with high levels of cerebral lactate. CONCLUSION: We recommend screening for mutations in AARS2 gene in CSF1R-negative patients, also in the absence of a clear family history and peculiar MRI findings. Our results also suggest that findings of conventional MRI and MR spectroscopy may be useful in prompting the genetic screening.

Cerebral Mitochondrial Microangiopathy Leads to Leukoencephalopathy in Mitochondrial Neurogastrointestinal Encephalopathy.

BACKGROUND AND PURPOSE: Mitochondrial neurogastrointestinal encephalopathy is a rare disorder due to recessive mutations in the thymidine phosphorylase gene, encoding thymidine phosphorylase protein required for mitochondrial DNA replication. Clinical manifestations include gastrointestinal dysmotility and diffuse asymptomatic leukoencephalopathy. This study aimed to elucidate the mechanisms underlying brain leukoencephalopathy in patients with mitochondrial neurogastrointestinal encephalopathy by correlating multimodal neuroradiologic features to postmortem pathology. MATERIALS AND METHODS: Seven patients underwent brain MR imaging, including single-voxel proton MR spectroscopy and diffusion imaging. Absolute concentrations of metabolites calculated by acquiring unsuppressed water spectra at multiple TEs, along with diffusion metrics based on the tensor model, were compared with those of healthy controls using unpaired t tests in multiple white matters regions. Brain postmortem histologic, immunohistochemical, and molecular analyses were performed in 1 patient. RESULTS: All patients showed bilateral and nearly symmetric cerebral white matter hyperintensities on T2-weighted images, extending to the cerebellar white matter and brain stem in 4. White matter, N-acetylaspartate, creatine, and choline concentrations were significantly reduced compared with those in controls, with a prominent increase in the radial water diffusivity component. At postmortem examination, severe fibrosis of brain vessel smooth muscle was evident, along with mitochondrial DNA replication depletion in brain and vascular smooth-muscle and endothelial cells, without neuronal loss, myelin damage, or gliosis. Prominent periependymal cytochrome C oxidase deficiency was also observed. CONCLUSIONS: Vascular functional and histologic alterations account for leukoencephalopathy in mitochondrial neurogastrointestinal encephalopathy. Thymidine toxicity and mitochondrial DNA replication depletion may induce microangiopathy and blood-brain-barrier dysfunction, leading to increased water content in the white matter. Periependymal cytochrome C oxidase deficiency could explain prominent periventricular impairment.

Genotype-phenotype and OCT correlations in Autosomal Dominant Optic Atrophy related to OPA1 gene mutations: Report of 13 Italian families.

Mutations in OPA1 are responsible of 32-89% cases of Autosomal Dominant Optic Atrophy (ADOA). OPA1 ADOA usually presents in childhood with bilateral, progressive visual loss due to retinal ganglion cells neurodegeneration, but environmental factors are supposed to influence onset and phenotype. Sixty Italian OPA1 mutations carriers (fifty-two symptomatic), belonging to thirteen families, underwent neuro-ophthalmologic evaluation. Visual acuity (n=60) and Optical Coherence Tomography (OCT) (n=12) were compared in missense mutations (OPA-M) versus haploinsufficiency-inducing mutations (OPA-H) and correlated with age. Presence of plus phenotypes was investigated. We found four known mutations, the most common being missense c.1034G>A, and a new missense mutation, c1193A>C, the latter in a 54-yrs old female with late-onset phenotype. Visual acuity, colour sensitivity, and optic disc atrophy were sensitive indicators of disease. OCT RNFL thickness was reduced in OPA1 compared to controls. OPA-M showed worst visual acuity than OPA-H, but not more frequent plus-phenotype, observed only in four OPA-H patients. In both groups, visual acuity worsened with age. Our data confirm worst vision in OPA-M, but not increased plus-phenotype. Since most patients belonged to nine families from south-eastern Sicily (a famous region for the cult of St. Lucy, patron of the blinds) local genetic and environmental factors might have accounted for the low occurrence of plus-phenotypes.

Pregnancy in CADASIL.

OBJECTIVES: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited cerebral small vessel disease caused by NOTCH3 gene mutations. CADASIL women are frequently considered at high risk of systemic vascular events during pregnancy and often prescribed with antithrombotic drugs. This decision is not evidence-based considering the lack of data about pregnancy outcome in CADASIL. We describe our experience on pregnancy in CADASIL patients. MATERIALS AND METHODS: We reviewed records of 50 CADASIL females followed in our center, and we collected prospective information in six patients for a total of 93 pregnancies. RESULTS: No woman had the disease onset or suffered from cerebral vascular ischemic events during pregnancy. Sixteen miscarriages (17.2%) were recorded. There were 72 vaginal births, and five cesarean sections. Considering the six patients followed prospectively (for a total of eight pregnancies), data on fetal growth and newborns weight were in line with those from the general population. Considering gestational complications, we recorded mild proteinuria without hypertension in one patient and hyperinsulinemia and pre-eclampsia in another affected by a known nephropathy. Antithrombotic drugs were used in three patients, in one for an unrelated coexisting prothrombotic condition. CONCLUSIONS: CADASIL does not seem to be associated with an unfavorable outcome of pregnancy either for women and fetuses. Patients and treating physicians should be reassured that pregnancy can be safely initiated in CADASIL, as there is no evidence to support a specific preventive antithrombotic treatment during pregnancy in CADASIL. Larger studies are needed to definitively confirm these conclusions.

Validation of plasma microRNAs as biomarkers for myotonic dystrophy type 1.

Non-invasive and simple to measure biomarkers are still an unmet need for myotonic dystrophy type 1 (DM1). Indeed, muscle biopsies can be extremely informative, but their invasive nature limits their application. Extracellular microRNAs are emerging humoral biomarkers and preliminary studies identified a group of miRNAs that are deregulated in the plasma or serum of small groups of DM1 patients. Here we adopted very stringent selection and normalization criteria to validate or disprove these miRNAs in 103 DM1 patients and 111 matched controls. We confirmed that 8 miRNAs out of 12 were significantly deregulated in DM1 patients: miR-1, miR-27b, miR-133a, miR-133b, miR-206, miR-140-3p, miR-454 and miR-574. The levels of these miRNAs, alone or in combination, discriminated DM1 from controls significantly, and correlated with both skeletal muscle strength and creatine kinase values. Interestingly, miR-133b levels were significantly higher in DM1 female patients. Finally, the identified miRNAs were also deregulated in the plasma of a small group (n = 30) of DM2 patients. In conclusion, this study proposes that miRNAs might be useful as DM1 humoral biomarkers.

Clinical, familial, and neuroimaging features of CADASIL-like patients.

OBJECTIVES: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited small vessel disease caused by NOTCH3 mutations. There are no clinical and neuroimaging findings pathognomonic of the disease. The aim of this paper was to provide a description of a group of NOTCH3-negative patients with a phenotype closely resembling that of CADASIL. MATERIALS AND METHODS: We performed NOTCH3 analysis (exons 2-23) in 117 probands because of a clinician's suspicion of CADASIL. The CADASIL scale, a recently developed tool that allows to better select patients for NOTCH3 analysis, was retrospectively applied to NOTCH3-negative patients; the patient subgroup that scored higher than the screening cutoff for CADASIL was defined as CADASIL-like. RESULTS: Thirty-four CADASIL-like patients (mean age at onset 57.8 years [52.1-63.4], 50% males) were identified. Compared with 25 patients with CADASIL for clinical, familial, and neuroimaging features, only the following variables were significantly (α level <0.05) different in frequency between patients with CADASIL and CADASIL-like patients: a positive family history for stroke at age ≤ 60 years, more frequent in patients with CADASIL, and hypertension, more frequent in CADASIL-like patients. CONCLUSIONS: Our experience highlights the growing number of patients presenting with a high suspicion of a cerebral small vessel disease with an autosomal dominant pattern of inheritance and a phenotype closely similar to that of CADASIL but without NOTCH3 mutations. This group remains to be characterized from the genetic point of view. The role of other genes or NOTCH3 alterations on exons other than 2-23 or introns has to be further assessed.

Adult-Onset Genetic Leukoencephalopathies. Focus on the More Recently Defined Forms.

Inherited white matter (WM) disorders include a heterogenous group of disorders affecting brain white matter and associated with myelin, axonal and glial cells or vascular pathology. Often a wide range of overlapping neurological manifestations possibly associated with variable systemic involvement are found in these disorders making clinical diagnosis challenging. Advances in molecular genetics enabled the identification of the responsible genes of an increasing number of previously undefined forms. This review focuses on genetic leukoencephalopathies with exclusive adulthood presentation, most of which have an autosomal dominant inheritance. The most common forms are related to vascular pathology, such as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL), COL4A1-related leukoencephalopathy, retinal vasculopathy with cerebral leukodystrophy (RVCL), and polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL). Also cerebroretinal microangiopathy with cysts and calcifications (CRMCC), which presents a prevalent infantile onset, will be detailed because of the vascular based myelin damage and the recent genetic characterization. Other adult onset (AO) leukoencephalopathies, such as the recently genetically defined hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS), adult-onset autosomal dominant leukodystrophy (ADLD) due to LMNB1 duplication, adult polyglucosan body disease (APBD), and fragile X-associated tremor/ataxia syndrome (FXTAS) will be detailed shortly. Short notes on the clinical and MRI features of late onset variants of the classical infantile-onset leukodystrophies mostly related to metabolic disorders will also be given. Finally, palliative, curative and experimental treatment options are here summarized.

Influence of vascular risk factors and neuropsychological profile on functional performances in CADASIL: results from the MIcrovascular LEukoencephalopathy Study (MILES).

BACKGROUND AND PURPOSE: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited cerebral small vessel disease that may lead to disability and whose phenotype modulators are still unknown. METHODS: In the MIcrovascular LEukoencephalopathy Study (MILES), we assessed the influence of vascular risk factors and the effect of different cognitive domains (memory, psychomotor speed and executive functions) performances on functional abilities in CADASIL in comparison with age-related leukoencephalopathy (ARL). RESULTS: We evaluated 51 CADASIL patients (mean age 50.3 ± 13.8 years, 47.1% males) and 68 ARL patients (70.6 ± 7.4 years, 58.8% males). Considering vascular risk factors, after adjustment for age, CADASIL patients had higher mean BMI values than ARL patients. Stroke history frequency was similar in the two groups. After adjustment for age, more CADASIL patients were disabled (impaired on ≥ 2 items of the Instrumental Activities of Daily Living scale) in comparison with ARL patients, and CADASIL patients had worse functional performances evaluated with the Disability Assessment for Dementia (DAD) scale. In CADASIL patients, hypertension was related to both DAD score and disability. The cognitive profile of CADASIL and ARL patients was similar, but on a stepwise linear regression analysis functional performances were mainly associated with the memory index (ß = -0.418, P < 0.003) in CADASIL patients and the executive function index (ß = -0.321, P = 0.028) in ARL. CONCLUSIONS: This study suggests that hypertension may contribute to functional impairment in CADASIL and that memory impairment has a large influence on functional decline in contrast with that observed in a sample of subjects with ARL.

Polyneuropathy in cerebrotendinous xanthomatosis and response to treatment with chenodeoxycholic acid.

Polyneuropathy has been reported in cerebrotendinous xanthomatosis (CTX), although its nature and possible association with certain genotypes and phenotypes are unclear. The effect of chronic administration of chenodeoxycholic acid (CDCA) on peripheral nerve conduction parameters is still debated. We report clinical, laboratory, and electrophysiological findings in 35 CTX patients. Twenty-six subjects (74.2 %) showed peripheral nerve abnormalities. Polyneuropathy was predominantly axonal (76.9 % of patients) and generally mild. No correlation was found between its presence and clinical or biochemical data. In polyneuropathic patients, CDCA treatment improved electrophysiological conduction parameters, irrespective of the duration of therapy. Improvement mainly concerned nerve conduction velocities, whereas most nerve amplitudes remained unchanged. This means that CDCA treatment did not influence the number of axons activated by maximum electrical stimulation but increased the conduction of the still-excitable fibers. Our findings may suggest that CDCA treatment promotes myelin synthesis in nerve fibers with residual unaffected axons. The effect of therapy may therefore depend largely on the extent of irreversible structural damage to axons.

Peripheral neuropathy in late-onset Krabbe disease: report of three cases.

Late-onset Krabbe disease may have variable misleading clinical manifestations and be a puzzling problem for physicians. We report clinical and peripheral nerve studies of three patients with adult-onset Krabbe disease. Two cases had a predominantly spastic paraparesis; in one case, the symptoms mimicked a cerebrovascular disorder. Predominantly, demyelinating neuropathy was observed in one case and axonal neuropathy in two cases. In all cases, no typical intracytoplasmic inclusions were found. These observations suggest that peripheral neuropathy in adult-onset Krabbe disease has variable clinical and pathological characteristics, different from those described in the classic form.

GFAP mutations, age at onset, and clinical subtypes in Alexander disease.

OBJECTIVE: To characterize Alexander disease (AxD) phenotypes and determine correlations with age at onset (AAO) and genetic mutation. AxD is an astrogliopathy usually characterized on MRI by leukodystrophy and caused by glial fibrillary acidic protein (GFAP) mutations. METHODS: We present 30 new cases of AxD and reviewed 185 previously reported cases. We conducted Wilcoxon rank sum tests to identify variables scaling with AAO, survival analysis to identify predictors of mortality, and χ(2) tests to assess the effects of common GFAP mutations. Finally, we performed latent class analysis (LCA) to statistically define AxD subtypes. RESULTS: LCA identified 2 classes of AxD. Type I is characterized by early onset, seizures, macrocephaly, motor delay, encephalopathy, failure to thrive, paroxysmal deterioration, and typical MRI features. Type II is characterized by later onset, autonomic dysfunction, ocular movement abnormalities, bulbar symptoms, and atypical MRI features. Survival analysis predicted a nearly 2-fold increase in mortality among patients with type I AxD relative to those with type II. R79 and R239 GFAP mutations were most common (16.6% and 20.3% of all cases, respectively). These common mutations predicted distinct clinical outcomes, with R239 predicting the most aggressive course. CONCLUSIONS: AAO and the GFAP mutation site are important clinical predictors in AxD, with clear correlations to defined patterns of phenotypic expression. We propose revised AxD subtypes, type I and type II, based on analysis of statistically defined patient groups.

Wernicke encephalopathy after gastrointestinal surgery for cancer: causes of diagnostic failure or delay.

Wernicke encephalopathy (WE) is a neurological emergency due to thiamine deficiency. We aimed to identify clinical course and causes of diagnostic delay or failure of WE in a group of patients who underwent surgery for gastrointestinal tumors. A retrospective review of clinical, laboratory, neuroimaging, and therapeutic features of 10 patients with WE following abdominal surgery for cancer was carried out. Four patients died; in these subjects, diagnosis was delayed and supplementation of vitamin was absent or likely inadequate. Diagnostic delay or failure was also related to the coexistence of several medical complications at presentation masking typical symptoms of WE. In the surviving patients, outcome was influenced by promptness and type of therapy. Postoperative abdominal bleeding and number of subsequent operations may also had an effect. Postsurgical patients with gastrointestinal tumors may develop a subtle WE. The number of subsequent operations and the severity of postoperative complications may increase the risk of unrecognized WE. The disease should be suspected in postsurgical patients who have unexpected mental status changes, even under prophylactic treatment with vitamins. We suggest that prophylaxis with high doses of thiamine should be undertaken in patients with gastrointestinal tumors before surgery.

Clinical relevance and neurophysiological correlates of spasticity in cerebrotendinous xanthomatosis.

Cerebrotendinous xanthomatosis (CTX) is a rare neurometabolic disease due to defective activity of sterol 27-hydroxylase, with plasma and tissue cholestanol storage. Clinical phenotype is characterized by both systemic manifestations and neurological signs. Therapy with chenodeoxycholic acid (CDCA) suppresses abnormal bile acid synthesis. The purpose of the study was to assess the frequency and clinical relevance of spasticity in the CTX phenotype and to study the usefulness of transcranial magnetic stimulation (TMS) in detecting corticospinal tract damage and monitoring the effects of replacement therapy. Twenty-four CTX patients underwent clinical evaluation including general disability scores, pyramidal and cerebellar function scales, assessment of serum cholestanol and TMS. Nine patients who started CDCA therapy at baseline received clinical and neurophysiological follow up. All patients showed signs of pyramidal damage which were relevant for clinical disability in 18 out of 24 cases (75%), resulting in spastic paraparesis. TMS revealed corticospinal alterations even in subjects with mild clinical signs of corticospinal tract involvement. After CDCA treatment, serum cholestanol decreased to normal concentrations in all patients. Clinical picture was unchanged in seven out of nine cases; in two others pyramidal signs disappeared. A reduction in abnormal neurophysiological parameters was found. Spastic paraparesis is the most frequent and relevant neurological feature in CTX patients. Replacement treatment with CDCA can prevent the progression of pyramidal damage, especially if started early in the course of the disease. TMS represents a sensitive indicator of corticospinal tract dysfunction and subclinical improvements in pyramidal function after CDCA therapy.