Hereditary neuropathy with liability to pressure palsies

Journal of Neurology - Hereditary neuropathy with liability to pressure palsies (HNPP) is characterized by recurrent sensory and motor neuropathy in individual nerves starting in adolescence or...     

A new mutation in GJC2 associated with subclinical leukodystrophy

Recessive mutations in GJC2, the gene-encoding connexin 47 (Cx47), cause Pelizaeus–Merzbacher-like disease type 1, a severe dysmyelinating disorder. One recessive mutation (p.Ile33Met) has been associated with a much milder phenotype––hereditary spastic paraplegia type 44. Here, we present evidence that a novel Arg98Leu mutation causes an even milder phenotype––a subclinical leukodystrophy. The Arg98Leu mutant forms gap junction plaques in HeLa cells comparable to wild-type Cx47, but electrical coupling was 20-fold lower in cell pairs expressing Arg98Leu than for cell pairs expressing wild-type Cx47. On the other hand, coupling between Cx47Arg98Leu and Cx43WT expressing cells did not show such reductions. Single channel conductance and normalized steady-state junctional conductance–junctional voltage (G _j–V _j) relations differed only slightly from those for wild-type Cx47. Our data suggest that the minimal phenotype in this patient results from a reduced efficiency of opening of Cx47 channels between oligodendrocyte and oligodendrocyte with preserved coupling between oligodendrocyte and astrocyte, and support a partial loss of function model for the mild Cx47 associated disease phenotypes.     

Psychometrics evaluation of Charcot‐Marie‐Tooth Neuropathy Score (CMTNSv2) second version,using Rasch analysis

Charcot‐Marie‐Tooth Neuropathy Score second version (CMTNSv2) is a validated clinical outcome measure developed for use in clinical trials to monitor disease impairment and progression in affected CMT patients. Currently, all items of CMTNSv2 have identical contribution to the total score. We used Rasch analysis to further explore psychometric properties of CMTNSv2, and in particular, category response functioning, and their weight on the overall disease progression. Weighted category responses represent a more accurate estimate of actual values measuring disease severity and therefore could potentially be used in improving the current version. Copyright © 2014 John Wiley & Sons, Ltd.     

Adult-onset leukodystrophies from respiratory chain disorders: do they exist?

Respiratory chain disorders (RCDs) have been included in the differential diagnosis of adult-onset leukodystrophies. Here, we first report a 32-year-old female with an atypical, adult-onset, non-syndromic RCD due to a mitochondrial DNA deletion and manifesting as complicated ataxia. A ‘leukodystrophic’ pattern was found on brain MRI, but it was neither isolated nor predominant because of the presence of overt basal ganglia and infratentorial lesions, which led us to the proper diagnosis. Subsequently, we evaluated our series of patients with RCDs in order to verify whether a ‘leukodystrophic’ pattern with little or no involvement of deep grey structures and brainstem may be found in adult-onset RCDs, as reported in children. Among 52 patients with adult-onset RCDs, no case with a ‘leukodystrophic’ pattern was found, apart from three cases with a classical phenotype of mitochondrial neurogastrointestinal encephalopathy. In addition, no case of RCDs was found among six cases of adult-onset leukodystrophy of unknown origin and at least one feature suggestive of mitochondrial disease. The review of the literature was in agreement with these findings. Thus, we provide evidence that, unlike in children, RCDs should not be included in the differential diagnosis of adult-onset leukodystrophies, except when there are additional MRI findings or clinical features which unequivocally point towards a mitochondrial disorder.     

Pendular nystagmus in hypomyelinating leukodystrophy

We report the case of a 49-year old woman affected by hypomyelinating leukodystrophy. She presented with typical pendular nystagmus that was analyzed with video-oculography which is provided in the supplementary material of the report. The pendular nystagmus was accompanied by upper limb ataxia on the index-to-nose test. The video was partly recorded with a slow-motion technique in order to better demonstrate the ataxia and the pendular nystagmus. The brain MRI demonstrated a characteristic pattern of hypomyelination. Pendular nystagmus is a key clinical sign that contributes to the diagnosis of CNS hypomyelination when a leukodystrophic pattern is observed on brain MRI.     

Validation of the Italian version of the Charcot‐Marie‐Tooth disease Pediatric Scale

The Charcot‐Marie‐Tooth disease Pediatric Scale (CMTPedS) is a Rasch‐built clinical outcome measure of disease severity. It is valid, reliable, and responsive to change for children and adolescents aged 3 to 20 years. The aim of this study was to translate and validate an Italian version of the CMTPedS using a validated framework of transcultural adaptation. The CMTPedS (Italian) was translated and culturally adapted from source into Italian by two experts in CMT with good English language proficiency. The two translations were reviewed by a panel of experts in CMT. The agreed provisional version was back translated into English by a professional translator. The definitive Italian version was developed during a consensus teleconference by the same panel. CMT patients were assessed with the final version of the outcome measure and a subset had a second assessment after 2 weeks to evaluate test‐retest reliability. Seventeen patients with CMT aged 5 to 20 years (eight female) were evaluated with the CMTPedS (Italian), and test‐retest was performed in three patients. The CMTPedS (Italian) showed a high test‐retest reliability. No patient had difficulty in completing the scale. The instructions for the different items were clearly understood by clinicians and therefore the administration of the outcome measure was straight forward and easily understood by the children assessed. The CMTPedS (Italian) will be used for clinical follow‐up and in clinical research studies in the Italian population. The data is fully comparable to that obtained from the English language version.     

Validation of the Italian version of the SBMA Functional Rating Scale as outcome measure

The Spinal and Bulbar Muscular Atrophy Functional Rating Scale (SBMAFRS) is an established rating instrument used to assess the functional status of patients with Spinal and Bulbar Muscular Atrophy (SBMA). Our aim was to validate an Italian version of the scale. We administered the SBMAFRS to sixty SBMA patients during routine follow-up of clinical evaluations. To estimate the test stability, the scale was re-administered to a subset of 39 randomly selected patients after 8 weeks. The patients underwent clinical evaluation including 6-min walk. Psychometric analysis included reliability assessment and factorial analysis. To evaluate convergent validity, correlations between SBMAFRS items and muscular force assessed by manual testing, ALSFRS total score and subscales scores, and forced vital capacity, were performed. Internal consistency as measured by Cronbach’s alpha (total scale 0.85) was high. Test–retest reliability assessed by Spearman’s rho was also high. Principal component analysis with varimax rotation yielded a four-factor solution accounting for approximately 79 % of the variance. The scale total score and subscales score were strongly correlated with respective items and subscores of the ALSFRS, with respiratory function and with the 6-min walk test. In conclusion, we performed an Italian validation of the only existing disease-specific Functional Rating Scale for SBMA patients. This scale will be a useful tool not only in the clinical practice but also as an outcome measure in upcoming clinical trials.