The Relationships Between Ataxia and Cognition in Spinocerebellar Ataxia Type 2

The Cerebellum - The clinical spectrum of spinocerebellar ataxia type 2 includes motor manifestations and cognitive disturbances in executive functions, memory, and visuoconstructive skills. The...     

Low-Titer Anti-GAD-Antibody-Positive Cerebellar Ataxia

The majority of cases of anti-glutamic acid decarboxylase (GAD)-antibody-positive cerebellar ataxia are reported to have high levels of anti-GAD antibody, and the diagnostic value of low titers of anti-GAD antibody in a patient with cerebellar ataxia is still unknown. The purpose of this study was to verify the characteristics of low-titer-anti-GAD-antibody-positive cerebellar ataxia patients and the diagnostic value of low titers of anti-GAD antibody in patients with cerebellar ataxia. The subjects were six patients positive for low-titer GAD antibody (<100 U/mL). We examined them with MRI, including voxel-based morphometry, and with single-photon emission computed tomography and monitored the GAD antibody index in the cerebrospinal fluid. The levels of antineuronal, antigliadin, anti-SS-A, antithyroid antibodies, and of vitamins E, B1, and B12 were determined. Thoracic and abdominal CT scans were performed to exclude a paraneoplastic origin. We treated three patients with immunotherapy. All cases showed cortical cerebellar atrophy. The GAD antibody index in three of the five patients reviewed was >1.0. Two of the six patients were thyroid antibody-positive, and one was both antinuclear- and anti-SS-A antibody-positive. After the administration of immunotherapy to three patients, two showed clear effectiveness, and one, transient effectiveness. Effectiveness was greatest in the two patients with familial occurrence of the disease. In cerebellar ataxia, regardless of family history or isolated illness, it is critical to measure the GAD antibody level, and, even with a low titer level, if the result is positive, immunotherapy should be considered.     

Gluten Ataxia in Japan

Gluten ataxia, a type of cerebellar ataxia caused by exposure to gluten in sensitive patients, has been considered common in the USA and Europe, and rare in Asia. We measured anti-deamidated gliadin peptide (DGP) antibody levels in 49 patients with cerebellar ataxia, excluding those with multiple system atrophy, hereditary spinocerebellar ataxia, or cancer, as well as those who were receiving oral administration of phenytoin. Anti-DGP antibody was positive in eight (16.3 %) patients, five of these patients were positive only for IgA, one was positive for both IgG and IgA, and two were positive only for IgG antibody. Intravenous immunoglobulin was administered to five of the eight patients, and was markedly effective in one, moderately effective in two, and ineffective in two. Steroid therapy was administered to four patients, but none had an apparent response. Ataxia symptoms improved in one patient treated with a gluten-free diet only. Although it had been thought to be extremely rare in Asia, we speculate that more than 10 % of cerebellar ataxia patients in Japan currently have gluten ataxia; therefore, measuring anti-DGP antibody or anti-gliadin antibody in cerebellar ataxia patients in Asia is important.     

POLG-Associated Ataxia Presenting as a Fragile X Tremor/Ataxia Phenocopy Syndrome

Hyperintensities in the middle cerebellar peduncles (MCP), known as the MCP sign, and progressive late-onset ataxia constitute major characteristics of the fragile X tremor/ataxia syndrome (FXTAS). Here, we describe a 60-year-old male affected by ataxia due to biallelic mutations in the mitochondrial polymerase gamma (POLG) gene in which hyperintensities of the middle cerebellar peduncles (MCP) were found. The initial suspicion of FXTAS was however ruled out by a normal CGG expansion size in the FMR1 gene. We discuss the features of late-onset POLG-A as a phenocopy of FXTAS.     

Ataxia and hereditary disorders

The last decade has seen great changes in the diagnosis of inherited ataxias. Previously mysterious diseases are now recognized to be caused by specific mutations for which genetic screening is readily available. In many cases, the discovery of the molecular basis has broadened the definition of possible clinical manifestations of particular inherited ataxias. The type of mutation underlying the more common forms of inherited ataxia-unstable trinucleotide repeat expansions-helps to explain some of the unusual features of these diseases. This article reviews recent genetic advances in ataxia. The aim is not to present an exhaustive summary but rather to provide guidance in evaluating ataxia, particularly with respect to recent molecular genetic findings.     

Ataxia and the cerebellum

Ataxia, an abnormality in the fine control of movement and posture, is a common neurologic sign in the pediatric population. While ataxia may be due to lesions in a variety of locations throughout the peripheral and central nervous systems, it is most commonly due to dysfunction of the cerebellum. It is critically important for child neurologists to recognize ataxia and to master its differential diagnosis because many of the diseases that induce ataxia in children are treatable and may require urgent attention.     

Cerebellar Stimulation in Ataxia

The cerebellum plays an important role in movement execution and motor control by modulation of the primary motor cortex (M1) through cerebello-thalamo-cortical connections. Transcranial magnetic stimulation (TMS) allows direct investigations of neural networks by stimulating neural structures in humans noninvasively. The motor evoked potential to single-pulse TMS of M1 is used to measure the motor cortical excitability. A conditioning stimulus over the cerebellum preceding a test stimulus of the contralateral M1 enables us to study the cerebellar regulatory functions on M1. In this brief review, we describe this cerebellar stimulation method and its usefulness as a diagnostic tool in clinical neurophysiology.