Genotype-specific spinal cord damage in spinocerebellar ataxias: an ENIGMA-Ataxia study.

BACKGROUND: Spinal cord damage is a feature of many spinocerebellar ataxias (SCAs), but well-powered in vivo studies are lacking and links with disease severity and progression remain unclear. Here we characterise cervical spinal cord morphometric abnormalities in SCA1, SCA2, SCA3 and SCA6 using a large multisite MRI dataset. METHODS: Upper spinal cord (vertebrae C1-C4) cross-sectional area (CSA) and eccentricity (flattening) were assessed using MRI data from nine sites within the ENIGMA-Ataxia consortium, including 364 people with ataxic SCA, 56 individuals with preataxic SCA and 394 nonataxic controls. Correlations and subgroup analyses within the SCA cohorts were undertaken based on disease duration and ataxia severity. RESULTS: Individuals in the ataxic stage of SCA1, SCA2 and SCA3, relative to non-ataxic controls, had significantly reduced CSA and increased eccentricity at all examined levels. CSA showed large effect sizes (d>2.0) and correlated with ataxia severity (r<-0.43) and disease duration (r<-0.21). Eccentricity correlated only with ataxia severity in SCA2 (r=0.28). No significant spinal cord differences were evident in SCA6. In preataxic individuals, CSA was significantly reduced in SCA2 (d=1.6) and SCA3 (d=1.7), and the SCA2 group also showed increased eccentricity (d=1.1) relative to nonataxic controls. Subgroup analyses confirmed that CSA and eccentricity are abnormal in early disease stages in SCA1, SCA2 and SCA3. CSA declined with disease progression in all, whereas eccentricity progressed only in SCA2. CONCLUSIONS: Spinal cord abnormalities are an early and progressive feature of SCA1, SCA2 and SCA3, but not SCA6, which can be captured using quantitative MRI.

Optic Disc and Retinal Architecture Changes in Patients with Spinocerebellar Ataxia Type 2.

BACKGROUND: ATXN2 is the causative gene of spinocerebellar ataxia type 2 (SCA2) and has been implicated in glaucoma pathogenesis. Therefore, studying ocular changes in SCA2 could uncover clinically relevant changes. OBJECTIVE: The aim was to investigate optic disc and retinal architecture in SCA2. METHODS: We evaluated 14 patients with SCA2 and 26 controls who underwent intraocular pressure measurement, fundoscopy, and macular and peripapillary spectral domain optical coherence tomography (SD-OCT). We compared SD-OCT measurements in SCA2 and controls, and the frequency of glaucomatous changes among SCA2, controls, and 76 patients with other SCAs (types 1, 3, 6, and 7). RESULTS: The macula, peripapillary retinal nerve fiber and inner plexiform layers were thinner in SCA2 than in controls. Increased cup-to-disc ratio was more frequent in SCA2 than in controls and other SCAs. CONCLUSIONS: Ocular changes are part of SCA2 phenotype. Future studies should further investigate retinal and optic nerve architecture in this disorder.

Sarcoid optic neuropathy.

A 45-year-old woman presented with sudden complete vision loss in her left eye and retroorbital pain worsened by eye movements. A previous milder episode of vision loss had occurred in the same eye 1 year before, with complete recovery after high-dose intravenous methylprednisolone. She had no light perception in the left eye with a swollen optic disc, but with a normal right optic disc. There were no systemic manifestations or infections. MR scan of the brain showed extensive enlargement and enhancement of the left optic nerve and optic chiasm. After excluding infections and autoimmune markers, a left optic nerve biopsy confirmed non-caseating granulomas, leading to a diagnosis of neurosarcoidosis.

Post-transplant lymphoproliferative disorder myeloradiculopathy.

A 56-year-old woman developed progressive subacute lower limb weakness with sensory and autonomic abnormalities. She had received a living-donor kidney transplantation 21 years before for end-stage chronic kidney disease and took mycophenolate mofetil and prednisolone. MR scan of the spinal cord showed bilateral cauda equina gadolinium enhancement and MR scan of the brain showed enhancing nodular hyperintensities in the internal capsule and globus pallidus. Cerebrospinal fluid (CSF) showed a pleocytosis with extremely low glucose, and positive DNA-PCR for Epstein-Barr virus. Her condition worsened despite empirically guided antimicrobial treatment. CSF immunophenotyping later identified mature, clonal B lymphocytes of large size, expressing CD19, CD20, CD200 antigens, and kappa light chain immunoglobulin, with absent CD5 and CD10 expression. We diagnosed a myeloradiculopathy from a monomorphic post-transplant lymphoproliferative disorder. This condition occurs after kidney transplantation and falls on the lymphoma spectrum. We review its clinical features, diagnosis and management.

Ischaemic lumbosacral plexopathy following aortic dissection.

A 57-year-old man was diagnosed with acute myocardial infarction and Stanford type A aortic dissection that had spread to the common iliac arteries. He underwent a Bentall procedure for vascular repair. Immediately after surgery, he developed numbness and severe weakness in his left leg. On examination, he had hypotonia, absent deep tendon reflexes, weakness in the left leg (Medical Research Council (MRC) scale for muscle strength - 0/5 distal, 3/5 proximal) and reduced sensation in the left leg. Electromyography confirmed subacute involvement of the left lumbar and lumbosacral plexus. MR scan of the lumbar plexus showed diffuse muscle oedema involving the left gluteus maximus. We diagnosed ischaemic lumbosacral plexopathy secondary to extensive aorta dissection and internal iliac artery occlusion. We discuss the clinical features of ischaemic plexopathy and the diagnostic approach and review the vascular anatomy of the lumbosacral plexus.

RFC1-Related Disorder: In Vivo Evaluation of Spinal Cord Damage.

BACKGROUND: RFC1-related disorder is a novel heredodegenerative condition with a broad phenotypic spectrum. Its neuropathological bases are not yet fully understood, particularly regarding the pattern, extent, and clinical relevance of spinal cord (SC) damage. OBJECTIVES: The objectives were to determine the SC structural signature in RFC1-related disorder in vivo and to identify potential clinical correlates for these imaging abnormalities. METHODS: We enrolled 17 subjects with biallelic RFC1 (AAGGG)n expansions and 11 age- and sex-matched healthy controls that underwent multimodal magnetic resonance imaging SC acquisitions in a 3T Philips Achieva scanner. Both global morphometry and tract-specific analyses were then performed across all cervical levels. Between-group comparisons were assessed using nonparametric tests. RESULTS: In the patient group, mean age and disease duration were 62.9 ± 9.3 and 9.3 ± 4.0, respectively. Compared to controls, patients had remarkable SC cross-sectional area reduction along all cervical levels but anteroposterior flattening only in the lower cervical levels. There was also prominent SC gray matter atrophy. Diffusivity abnormalities were identified in the dorsal columns but not in the lateral corticospinal tracts. Disease severity did not correlate with these imaging parameters. CONCLUSION: SC damage is a hallmark of RFC1-related disorder and characterized by gray as well as white matter involvement. In particular, dorsal columns are severely and diffusely affected. The clinical correlates of these imaging abnormalities still deserve additional investigations. © 2022 International Parkinson and Movement Disorder Society.

Clinical and Genetic Characterization of Brazilian Patients with Ataxia and Oculomotor Apraxia.

BACKGROUND: Ataxia with oculomotor apraxia (AOA) is characterized by early-onset cerebellar ataxia associated with oculomotor apraxia. AOA1, AOA2, AOA3, and AOA4 subtypes may present pathogenic variants in APTX, SETX, PIK3R5, and PNKP genes, respectively. Mutations in XRCC1 have been found to cause autosomal recessive spinocerebellar ataxia-26 (SCAR26) now considered AOA5. OBJECTIVES: To examine a cohort of Brazilians with autosomal recessive cerebellar ataxia plus oculomotor apraxia and determine the frequencies of AOA subtypes through genetic investigation. METHODS: We evaluated clinical, biomarkers, electrophysiological, and radiological findings of 52 patients with AOA phenotype and performed a genetic panel including APTX, SETX, PIK3R5, PNKP, and XRCC1. RESULTS: We found pathogenic variants in SETX (15 patients), PNKP (12), and APTX (5). No mutations in PIK3R5 or XRCC1 were identified. CONCLUSIONS: AOA2 and AOA4 were the most common forms of AOA in Brazil. Mutations in PIK3R5 and XRCC1 were not part of this genetic spectrum. © 2022 International Parkinson and Movement Disorder Society.

Diagnostic Yield of Whole Exome Sequencing for Adults with Ataxia: a Brazilian Perspective.

Previous studies using whole exome sequencing (WES) have shown that a significant proportion of adult patients with undiagnosed ataxia in European and North American cohorts have a known genetic cause. Little is known about the diagnostic yield of WES in non-Caucasian ataxic populations. Herein, we used WES to investigate a Brazilian cohort of 76 adult patients with idiopathic ataxia previously screened for trinucleotide expansions in known ataxia genes. We collected clinical and radiological data from each patient. WES was performed following standard procedures. Only variants labeled as pathogenic or likely pathogenic according to American college of medical genetics and genomics (ACMG) criteria were retrieved. We determined the diagnostic yield of WES for the whole cohort and also for subgroups defined according to presence or not of pyramidal signs, peripheral neuropathy, and cerebellar atrophy. There were 41 women and 35 men. Mean age at testing was 48 years. Pyramidal signs, peripheral neuropathy, tremor, and cerebellar atrophy were found in 38.1%, 13.1%, 10.5%, and 68.3% of all subjects, respectively. Diagnostic yield of WES was 35.5%. Thirty-six distinct mutations were found in 20 different genes, determining the diagnosis of 18 autosomal recessive and 9 autosomal dominant ataxias. SACS and SPG7 were the most frequently found underlying genes. WES performed better in the subgroup with vs the subgroup without spasticity (p = 0.005). WES was diagnostic in 35.5% of cases of the Brazilian cohort of ataxia cases. These results have implications for diagnosis, genetic counseling and eventually treatment.

Dystonia, Chorea, and Ataxia: Three Challenging Cases.

Movement disorders comprise a heterogeneous and complex group of neurological disorders that increase (hyperkinetic) or decrease (hypokinetic) the speed or amplitude of movements, or disrupt their coordinated sequencing. In this article, we describe three instructive cases, exemplifying classic movement disorders, namely dystonia, chorea, and ataxia. We highlight the diagnostic approach based on clinical clues, syndromic reasoning, evaluation, and management recommendations. Each case ends with key messages for the clinicians.

Brain Structural Signature of RFC1-Related Disorder.

BACKGROUND: The cerebellar ataxia, neuropathy, and vestibular areflexia syndrome was initially described in the early 1990s as a late-onset slowly progressive condition. Its underlying genetic cause was recently mapped to the RFC1 gene, and additional reports have expanded on the phenotypic manifestations related to RFC1, although little is known about the pattern and extent of structural brain abnormalities in this condition. OBJECTIVE: The aim is to characterize the structural signature of brain damage in RFC1-related disorder, correlating the findings with clinical symptoms and normal brain RFC1 expression. METHODS: We recruited 22 individuals with molecular confirmation of RFC1 expansions and submitted them to high-resolution 3T magnetic resonance imaging scans. We performed multimodal analyses to assess separately cerebral and cerebellar abnormalities within gray and white matter (WM). The results were compared with a group of 22 age- and sex-matched controls. RESULTS: The mean age and disease duration of patients were 62.8 and 10.9 years, respectively. Ataxia, sensory neuronopathy, and vestibular areflexia were the most frequent manifestations, but parkinsonism and pyramidal signs were also noticed. We found that RFC1-related disorder is characterized by widespread and relatively symmetric cerebellar and basal ganglia atrophy. There is brainstem volumetric reduction along all its segments. Cerebral WM is also involved-mostly the corpus callosum and deep tracts, but cerebral cortical damage is rather restricted. CONCLUSION: This study adds new relevant insights into the pathophysiological mechanisms of RFC1-related disorder. It should no longer be considered a purely cerebellar and sensory pathway disorder. Basal ganglia and deep cerebral WM are additional targets of damage. © 2021 International Parkinson and Movement Disorder Society.

A Real-World Study of Cerebral 99mTc-TRODAT-1 Single-Photon Emission Computed Tomography (SPECT) Imaging of the Dopamine Transporter in Patients with Parkinson Disease from a Tertiary Hospital in Brazil.

BACKGROUND Studies on the routine clinical use of dopamine transporter (DAT) imaging have largely been conducted in Europe and the United States. In this real-world study, we investigated the use of cerebral 99mTc-TRODAT-1 SPECT imaging of DAT in patients with Parkinson disease (PD) at a tertiary hospital in Brazil. MATERIAL AND METHODS We included 119 patients with suspected PD or clinically unclear parkinsonism who underwent brain scintigraphy with 99mTc-TRODAT-1 during a 3-year period. Additionally, a brief interview was conducted with the physician who requested the scan to determine the usefulness of the method in clinical decision-making. RESULTS Regarding the scan requests, most were intended to evaluate or confirm dopaminergic denervation (69%), distinguish PD from essential tremor (10%), or distinguish degenerative parkinsonism from drug-induced parkinsonism (6%). Data analysis showed that scintigraphy with 99mTc-TRODAT-1 was useful in 85% of cases, changing the management of 75% of the patients who underwent a scan. The majority of physicians who requested the scan were neurologists, and 54% were self-reported movement disorder specialists. An inappropriate use of DAT imaging was seen in 5% of cases. CONCLUSIONS This study demonstrated that brain scintigraphy with the DAT ligand 99mTc-TRODAT-1 may influence diagnostic or therapeutic interventions, meaning that Brazilian physicians who requested the exam have taken in vivo DAT results into account at the time of clinical decision-making.

Cognitive and Psychiatric Evaluation in SYNE1 Ataxia.

SYNE1 gene mutations were identified as a cause of late-onset pure cerebellar syndrome. Non-cerebellar symptoms, including cognitive impairment, were already described in this condition. The aim of this study was to perform a detailed cognitive and psychiatric description of patients with SYNE1 gene mutations. We performed neuropsychological and psychiatric evaluations of six patients with SYNE1 ataxia and compared their performance with 18 normal controls paired for age and education level. SYNE1 ataxia patients present cognitive dysfunction, characterized by impairment in attention and processing speed domains. Otherwise, the psychiatric assessment reported low levels of overall behavioral symptoms with only some minor anxiety-related complaints. Although this is a small sample of patients, these results suggest that SYNE1 ataxia patients may represent a model to investigate effects of cerebellar degeneration in higher hierarchical cognitive functions. For further studies, abstract thinking impairment in schizophrenia may be related to dysfunction in cerebellum pathways.

Dentatorubro-Pallidoluysian Atrophy (DRPLA) among 700 Families with Ataxia in Brazil.

Dentatorubro-pallidoluysian atrophy (DRPLA) is a spinocerebellar ataxia (SCA) very rare in non-Asian populations. To date, DRPLA was undetected in the general Brazilian population. Adult-onset ataxic patients have been recruited from several Brazilian neurology and neurogenetics centers. CAG lengths at SCA1, SCA2, SCA3/MJD, SCA6, SCA7, SCA12, SCA17 and DRPLA associated genes, and ATTCT expansions at SCA10 gene were studied. A single DRPLA case detected is reported. Proband was a 69-year-old Brazilian woman of mixed ancestry, with a late-onset pure ataxia: her alleles at the associated gene, ATN1, presented 14/52 CAG repeats. History of gait ataxia and dementia was observed in two out of six siblings but was absent in her parents. This was the single DRPLA diagnosis obtained from 700 Brazilian unrelated cases with adult-onset ataxia, 487 of them with clear autosomal dominant inheritance. DRPLA accounted for 0.14% of all adult-onset ataxia cases and for 0.2% of families with autosomal dominant inheritance. Normal CAG repeats at ATN1 had a median (range) of 14 (5-20) repeats in other 410 Brazilian chromosomes. DRPLA is quite rare in Brazilian SCA families, which is consistent with the lack of large normal alleles in our population.

Late-Onset Friedreich's Ataxia (LOFA) Mimicking Charcot-Marie-Tooth Disease Type 2: What Is Similar and What Is Different?

Herein, we report a patient that presented with late-onset progressive steppage gait, neuropathy and pes cavus, suggesting Charcot-Marie-Tooth (CMT) disease. Subsequent genetic investigation confirmed Friedreich's ataxia (FRDA). We demonstrate that late-onset Friedreich's ataxia (LOFA) may be a CMT mimicker. This case reinforces that other genetic conditions may clinically resemble CMT. The clinical similarities between CMT and FRDA include a symmetrical neuropathy (axonal in FRDA), steppage gait, and eventually scoliosis. We suggest that late-onset forms of hereditary neuropathies should be carefully evaluated, since LOFA may be a CMT mimicker.

Spinal Cord Damage in Spinocerebellar Ataxia Type 1.

Spinocerebellar ataxia type 1 (SCA1) is an autosomal dominant disorder caused by a CAG repeat expansion, characterized by progressive cerebellar ataxia and pyramidal signs. Non-motor and extracerebellar symptoms may occur. MRI-based studies in SCA1 focused in the cerebellum and connections, but there are no data about cord damage in the disease and its clinical relevance. To evaluate in vivo spinal cord damage in SCA1, a group of 31 patients with SCA1 and 31 age- and gender-matched healthy controls underwent MRI on a 3T scanner. We used T1-weighted 3D images to estimate the cervical spinal cord area (CA) and eccentricity (CE) at three C2/C3 levels based on a semi-automatic image segmentation protocol. The scale for assessment and rating of ataxia (SARA) was used to quantify disease severity. The groups were significantly different regarding CA (47.26 ± 7.4 vs. 68.8 ± 5.7 mm2, p < 0.001) and CE values (0.803 ± 0.044 vs. 0.774 ± 0.043, p < 0.05). Furthermore, in the patient group, CA presented significant correlation with SARA scores (R = -0.633, p < 0.001) and CAGn expansion (R = -0.658, p < 0.001). CE was not associated with SARA scores (p = 0.431). In the multiple variable regression, CA was strongly associated with disease duration (coefficient -0.360, p < 0.05) and CAGn expansion (coefficient -1.124, p < 0.001). SCA1 is characterized by cervical cord atrophy and anteroposterior flattening. Morphometric analyses of the spinal cord MRI might be a useful biomarker in the disease.

Non-motor and Extracerebellar Features in Spinocerebellar Ataxia Type 2.

Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant degenerative disease. Pathological studies have demonstrated not only cerebellar and brainstem atrophy, but substantia nigra, motoneurons, basal ganglia, thalamus, and peripheral nerves involvement. These findings may explain non-motor and extra-cerebellar features in SCA2. We accessed the non-motor symptoms and extra-cerebellar signs in SCA2 patients in order to provide a better understanding on pathophysiological mechanisms and natural history of brain degeneration in the disease. Thirty-three SCA2 patients were evaluated and compared with 26 healthy subjects. We investigated the following variables: sleep disorders, cognitive deficit, olfactory impairment, urinary dysfunction, psychiatric symptoms, cramps, pain, movement disorders, and weight loss. SCA2 had a high frequency of REM sleep behavior disorder (48.48 %, N = 16) as well as excessive daytime sleepiness (42.42 %, N = 14). Chorea was present in 15.15 % (N = 5), dystonia in 27.27 % (N = 9), and parkinsonism in 27.27 % (N = 9). Slow saccadic pursuit was present in 87.87 % (N = 29) and ophtalmoparesis in 78.78 % (N = 26) of patients. Regarding sleep disorders, 18.18 % (N = 6) of patients had restless leg syndrome. Dysphagia was present in 39.39 % (N = 13), weight loss 24.24 % (N = 8), and urinary dysfunction 27.27 % (N = 9). Cramps was present in only 6 % of patients (N = 2). This study highlighted the high frequency of non-motor symptoms and extra-cerebellar signs in SCA2. Our findings demonstrate the widespread of nervous system involvement in SCA2 patients and contribute to better understand the natural history of brain degeneration in this genetic condition.

ALS5/SPG11/KIAA1840 mutations cause autosomal recessive axonal Charcot-Marie-Tooth disease.

Charcot-Marie-Tooth disease is a group of hereditary peripheral neuropathies that share clinical characteristics of progressive distal muscle weakness and atrophy, foot deformities, distal sensory loss, as well as diminished tendon reflexes. Hundreds of causative DNA changes have been found, but much of the genetic basis of the disease is still unexplained. Mutations in the ALS5/SPG11/KIAA1840 gene are a frequent cause of autosomal recessive hereditary spastic paraplegia with thin corpus callosum and peripheral axonal neuropathy, and account for ∼ 40% of autosomal recessive juvenile amyotrophic lateral sclerosis. The overlap of axonal Charcot-Marie-Tooth disease with both diseases, as well as the common autosomal recessive inheritance pattern of thin corpus callosum and axonal Charcot-Marie-Tooth disease in three related patients, prompted us to analyse the ALS5/SPG11/KIAA1840 gene in affected individuals with autosomal recessive axonal Charcot-Marie-Tooth disease. We investigated 28 unrelated families with autosomal recessive axonal Charcot-Marie-Tooth disease defined by clinical, electrophysiological, as well as pathological evaluation. Besides, we screened for all the known genes related to axonal autosomal recessive Charcot-Marie-Tooth disease (CMT2A2/HMSN2A2/MFN2, CMT2B1/LMNA, CMT2B2/MED25, CMT2B5/NEFL, ARCMT2F/dHMN2B/HSPB1, CMT2K/GDAP1, CMT2P/LRSAM1, CMT2R/TRIM2, CMT2S/IGHMBP2, CMT2T/HSJ1, CMTRID/COX6A1, ARAN-NM/HINT and GAN/GAN), for the genes related to autosomal recessive hereditary spastic paraplegia with thin corpus callosum and axonal peripheral neuropathy (SPG7/PGN, SPG15/ZFYVE26, SPG21/ACP33, SPG35/FA2H, SPG46/GBA2, SPG55/C12orf65 and SPG56/CYP2U1), as well as for the causative gene of peripheral neuropathy with or without agenesis of the corpus callosum (SLC12A6). Mitochondrial disorders related to Charcot-Marie-Tooth disease type 2 were also excluded by sequencing POLG and TYMP genes. An additional locus for autosomal recessive Charcot-Marie-Tooth disease type 2H on chromosome 8q13-21.1 was excluded by linkage analysis. Pedigrees originated in Italy, Brazil, Canada, England, Iran, and Japan. Interestingly, we identified 15 ALS5/SPG11/KIAA1840 mutations in 12 families (two sequence variants were never reported before, p.Gln198* and p.Pro2212fs*5). No large deletions/duplications were detected in these patients. The novel mutations seemed to be pathogenic since they co-segregated with the disease in all pedigrees and were absent in 300 unrelated controls. Furthermore, in silico analysis predicted their pathogenic effect. Our results indicate that ALS5/SPG11/KIAA1840 is the causative gene of a wide spectrum of clinical features, including autosomal recessive axonal Charcot-Marie-Tooth disease.