Unravelling the etiology of sporadic late-onset cerebellar ataxia in a cohort of 205 patients: a prospective study.

BACKGROUND: Despite recent progress in the field of genetics, sporadic late-onset (> 40 years) cerebellar ataxia (SLOCA) etiology remains frequently elusive, while the optimal diagnostic workup still needs to be determined. We aimed to comprehensively describe the causes of SLOCA and to discuss the relevance of the investigations. METHODS: We included 205 consecutive patients with SLOCA seen in our referral center. Patients were prospectively investigated using exhaustive clinical assessment, biochemical, genetic, electrophysiological, and imaging explorations. RESULTS: We established a diagnosis in 135 (66%) patients and reported 26 different causes for SLOCA, the most frequent being multiple system atrophy cerebellar type (MSA-C) (41%). Fifty-one patients (25%) had various causes of SLOCA including immune-mediated diseases such as multiple sclerosis or anti-GAD antibody-mediated ataxia; and other causes, such as alcoholic cerebellar degeneration, superficial siderosis, or Creutzfeldt-Jakob disease. We also identified 11 genetic causes in 20 patients, including SPG7 (n = 4), RFC1-associated CANVAS (n = 3), SLC20A2 (n = 3), very-late-onset Friedreich's ataxia (n = 2), FXTAS (n = 2), SCA3 (n = 1), SCA17 (n = 1), DRPLA (n = 1), MYORG (n = 1), MELAS (n = 1), and a mitochondriopathy (n = 1) that were less severe than MSA-C (p < 0.001). Remaining patients (34%) had idiopathic late-onset cerebellar ataxia which was less severe than MSA-C (p < 0.01). CONCLUSION: Our prospective study provides an exhaustive picture of the etiology of SLOCA and clues regarding yield of investigations and diagnostic workup. Based on our observations, we established a diagnostic algorithm for SLOCA.

Xeroderma pigmentosum complementation group F: A rare cause of cerebellar ataxia with chorea.

The complementation group F of Xeroderma pigmentosum (XP-F) is rare in the Caucasian population, and usually devoid of neurological symptoms. We report two cases, both Caucasian, who exhibited progressive cerebellar ataxia, chorea, a mild subcortical frontal cognitive impairment, and in one case severe polyneuropathy. Brain MRI demonstrated cerebellar (2/2) and cortical (1/2) atrophy. Both patients had only mild sunburn sensitivity and no skin cancer. Mini-exome sequencing approach revealed in ERCC4, two heterozygous mutations, one of which was never described (c.580-584+1delCCAAGG, exon 3), in the first case, and an already reported homozygous mutation, in the second case. These cases emphasize that XP-F is a rare cause of recessive cerebellar ataxia and can in some cases clinically mimic Huntington's disease due to chorea and executive impairment. The association of ataxia, chorea, and sun hypersensitivity are major guidance for the diagnosis, which should not be missed, in order to prevent skin neoplastic complications.

[Severe generalized dystonia due to postradiotherapy cerebral calcifications]. / Dystonie généralisée sévère liée à des calcifications cérébrales postradiques.

INTRODUCTION: Cerebral calcifications are a cause of secondary dystonia and may be an uncommon complication of radiotherapy. We report a very severe case of generalized dystonia due to postradiotherapy basal ganglia calcifications. CASE REPORT: An 8-year-old girl received 53 grays radiotherapy after surgery for craniopharyngioma. One year later she developed generalized dystonia. Computed tomography showed bilateral basal ganglia calcifications, especially of the lenticular nuclei. Pharmacological treatment with tetrabenazine, clonazepam and trihexiphenydile allowed a very limited improvement of dystonia; the course was complicated by dystonic storms and decompensations resulting from the iatrogenous panhypopituitarism. CONCLUSION: This case illustrates a severe complication of cranial irradiation which should be considered in the indications of this treatment, especially for children.

A new form of childhood onset, autosomal recessive spinocerebellar ataxia and epilepsy is localized at 16q21-q23.

Childhood ataxias are a complex set of inherited disorders. Ataxias associated with generalized tonic-clonic epilepsy are usually included with the progressive myoclonus epilepsies (PME). Five disease entities, Unverricht-Lundborg disease, Lafora's disease, neuronal ceroid lipofuscinoses, myoclonic epilepsy with ragged red fibres and sialidoses, account for the majority of PME cases. Two rare forms of ataxia plus epilepsy, sensory ataxic neuropathy, dysarthria and ophthalmoparesis, and infantile onset spinocerebellar ataxia were described recently and found to be caused by defective mitochondrial proteins. We report here a large consanguineous family from Saudi Arabia with four affected children presenting with generalized tonic-clonic epilepsy, ataxia and mental retardation, but neither myoclonus nor mental deterioration. MRI and muscle biopsy of one patient revealed, respectively, posterior white matter hyperintensities and vacuolization of the sarcotubular system. We localized the defective gene by homozygosity mapping to a 19 Mb interval in 16q21-q23 between markers D16S3091 and D16S3050. Linkage studies in this region will allow testing for homogeneity of this novel ataxia-epilepsy entity.

[A clinical, neurophysiological and molecular study of 12 patients from 4 families with spinal and bulbar muscular atrophy]. / L'amyotrophie bulbaire et spinale liée au chromosome X: une étude clinique, neurophysiologique et moléculaire de 12 patients issus de 4 familles.

INTRODUCTION: Spinal and bulbar muscular atrophy (SBMA) is an X-linked, late-onset neuro-endocrine disorder resulting from an expansion of a CAG repeat in the androgen receptor gene. Material and method. We report the detailed phenotypic study in a series of 12 SBMA patients evaluated in four kindreds. RESULTS: Clinical phenotypic spectrum varied considerably, ranging from childhood-onset weakness and atrophy mimicking limb-girdle myopathy in patients with 53 CAG repeats to isolated hyperCKemia in an adult with 42 CAG repeats. All male patients had gynecomastia. Two female carriers presented with paresthesias and hand action tremor. Homozygous deletions of SMN1 and SMN2 genes were not found in any patients. CONCLUSION: This report demonstrates that SBMA may present with a wider clinical spectrum than previously described and suggests that clinical phenotype severity in SBMA is partially linked to the number of CAG repeats. It also suggests that SMN1 and SMN2 genes do not act as modifying genes in SBMA.