R. Saponara

Supratentorial atrophy in spinocerebellar ataxia type 2: MRI study of 20 patients

Abstract There have been only few studies of brain magnetic resonance imaging (MRI) in spinocerebellar ataxia (SCA) type 2. We investigated 20 SCA2 patients, from 11 Sicilian families, and 20 age-matched control subjects using MRI. Our data confirm that olivopontocerebellar atrophy (OPCA) is the typical pattern in SCA2. We found no significant correlation between infratentorial atrophy, disease duration, or the number of CAG repeats in our SCA2 patients, but there was supratentorial atrophy in 12 patients, with a significant correlation between supratentorial atrophy and disease duration. OPCA appears to represent the “core” of the SCA2: however, central nervous system involvement is not limited to pontocerebellar structures. We therefore consider central nervous system degeneration in SCA2 as a widespread atrophy. MRI is helpful in diagnosing SCA, but it is not diagnostic in the absence of clinical and molecular studies. We suggest that serial MRI may play a role in evaluating “in vivo” the progressive steps of neurodegeneration in SCA2, for a better comprehension of the pathophysiology of this disorder.

Cognitive findings in spinocerebellar ataxia type 2: relationship to genetic and clinical variables.

Several authors have recently reported a broad cognitive impairment in autosomal dominant cerebellar ataxias (ADCAs) patients. However, only a few studies on neuropsychological features in spinocerebellar ataxia type 2 (SCA2) patients are present in the current literature. The aim of this study is to evaluate the cognitive impairment in a wide sample of SCA2 patients and to verify the role of different disease-related factors (age of onset, disease duration, and clinical severity) on intellectual abilities. We administered a battery of neuropsychological tests assessing handedness, attention, short- and long-term verbal and visuo-spatial memory, executive functions, constructive abilities, general intellectual abilities and depression to 18 SCA2 patients belonging to eight families who came to our observation. Evidence of impaired verbal memory, executive functions and attention was found. The cognitive status was partially related to clinical severity rather than to disease duration or age at onset of symptoms. We partially confirmed data on cognitive defects already reported by others but we also found defective attention skills as well as significant lower performances in a nonverbal intelligence task.

Changes of cortical excitability of human motor cortex in spinocerebellar ataxia type 2: A study with paired transcranial magnetic stimulation

The aim of this study was to evaluate motor cortex excitability in spinocerebellar ataxia type 2 (SCA2). Cortical silent period (CSP), motor thresholds, and intracortical inhibition and facilitation by paired transcranial magnetic stimulation (TMS) were investigated in 18 SCA2 patients and in 20 controls. The mean CSP duration and motor threshold after TMS were significantly increased in the patient group. Intracortical inhibition by paired TMS at short interstimulus intervals (ISIs) showed no significant differences between patients and controls; at longer ISIs, the expected facilitation of test responses, observed in control subjects, resulted significantly less marked in SCA2 patients at all the tested intervals. Our findings extend previous findings on cerebellar dysfunctions of varying aetiologies by investigating intracortical excitability in SCA2. In addition, this study demonstrates that the cortical excitability involvement found in SCA2 is independent on the cytosine-adenine-guanine repeat expansion. The neurophysiological alterations seen in our patients relate to the worsening of general clinical condition. Thus, we might speculate that changes of motor cortex excitability in SCA2 represent a slow neurodegenerative process characterized by gradual loss of cerebellar neurons leading to an increasing disturbance of the balance between inhibitory and excitatory circuits in the motor system.

Central motor conduction to lower limb after transcranial magnetic stimulation in spinocerebellar ataxia type 2 (SCA2)

OBJECTIVES To evaluate central motor conduction to lower limbs in spinocerebellar ataxia type 2 (SCA2). METHODS Transcranial magnetic stimulation was performed to study the corticospinal tracts of 18 patients with SCA2. RESULTS Central motor conduction time (CMCT) to lower limbs and thresholds were abnormal in 8 patients (44%); CMCT and thresholds were significantly correlated with disease duration and disability. CONCLUSIONS Corticospinal tract involvement is more frequent than previously reported in SCA2. Prolonged CMCT and increased threshold should not be used to differentiate between various type of autosomal dominant cerebellar ataxia. Similar to that reported in Friedreichs ataxia, we suggest that examining central motor conduction to the lower limbs may assist in evaluating the progressive steps of neurodegeneration in SCA2.

Clinical and molecular analysis of 11 Sicilian SCA2 families: influence of gender on age at onset

Autosomal dominant cerebellar ataxias (ADCAs) are a complex group of slowly progressive neurodegenerative disorders characterized by gait and stance ataxia, dysarthria and other symptoms of nervous system involvement. ADCA type I is the commonest form and is genetically heterogeneous; several loci have been identified. Spinocerebellar ataxia type 2 (SCA2) has been mapped to chromosome 12, with expanded cytosine‐adenine‐guanine (CAG) repeats being identified as the mutational cause of the disease. We investigated 15 families, all originating from mid‐eastern Sicily, with ADCA type I; molecular studies performed in 12 families showed the SCA2 mutation to be present in 11 of them (91.6%) ‐ the highest occurrence so far reported in the literature. The CAG repeat of the affected alleles varied between 34 and 44 repeats. Age at onset and repeat length revealed an inverse correlation. Mean age at onset was 37.32 ± 16.74 years, and occurred earlier in males than in females. There were no differences in mean CAG repeat units between the sexes. However, a higher instability of CAG repeats was observed for paternal transmission than for maternal transmission. Age at onset and anticipation were not related to parental transmission. Our data suggest that in SCA2 an unknown sexlinked factor may play a role in the modulation of toxic effects of the polyglutamine tract.

Levetiracetam improves intention tremor in fragile x-associated tremor/ataxia syndrome.

Fragile X-associated tremor/ataxia syndrome is a recently discovered disorder affecting more of one third of older adult male carriers of premutation alleles of fragile X mental retardation 1 (FMR1 gene). There is no established treatment.The 66-year-old right-handed grandfather of a boy with fragile X syndrome, a carrier of premutation alleles of FMR1 gene, developed an action tremor in his right hand when writing. His writing became large and completely illegible. Administration of levetiracetam was associated with subjective and objective improvement, and handwriting became possible again. Levetiracetam was well tolerated, and no adverse effects were reported.

Identification of SCA2 mutation in cases of spinocerebellar ataxia with no family history in mid-eastern Sicily.

Abstract Differential diagnosis between autosomal dominant cerebellar ataxia type I (ADCA I) and idiopathic cerebellar ataxia type P (IDCA-P) is very difficult given only clinical and neuroradiological data. The only certain distinctive characteristic is the presence or absence of family history. We observed 7 patients with late-onset cerebellar ataxia associated with other non-cerebellar signs and without a family history of the disease in which clinical signs were comparable to symptoms found in SCA2. The neuroradiological study showed olivopontocerebellar atrophy in all patients and the presence of hyperintensity of the transverse pontine fibers in 6 patients (85.6%); molecular analysis showed SCA2 mutations in 2 patients. We also report the case of a patient who was initially considered as IDCA-P but who was later correctly identified as SCA2 with an atypical family history (false IDCA-P), after a genetic mutation was found and following an interview with the mother. Our data suggest that spinocerebellar ataxia syndrome should be defined as idiopathic not only after having excluded the possible symptomatic causes but also in the absence of family history, after having excluded the presence of genetic mutation. We believe that family history, in late-onset spinocerebellar ataxia, cannot be considered as the differential criterion among hereditary (ADCA-I) and non-hereditary (IDCA-P) forms; molecular analysis is required for a correct diagnosis.

Primary Neurosarcoidosis A Case Report

Neurosarcoidosis is primarily a disease of the leptomeninges although parenchymal involvement is less common. We describe a patient presenting with symptoms and signs of intracranial hypertension and diabetes insipidus. Brain CT scan showed periventricular and hypothalamic areas of increased density that enhanced after contrast administration. After steroid treatment, neurological symptoms resolved but diabetes insipidus persisted. MRI study performed 10 days later revealed a significant reduction of the previously demonstrated lesions, that were slightly hyperintense in T2-weighted images, while the hypothalamic lesions enhanced after Gd-DTPA administration. These lesions, due probably to infallamatory infiltration and/or oedema, were not present in a neuroradiological follow-up performed 2 and 3 months later. Two months after neurological onset the patient developed a systemic sarcoidosis. Primary neurosarcoidosis should be suspected in the presence of multiple intracranial lesions which improve after steroid therapy. MRI is the neuroradiological study of choice in the diagnosis and follow-up of this rare disease.