Ataxia encompasses a large group of rare disorders characterized by irregular movements, decreased coordination, imbalance, kinetic tremor, wide-based stance, and dysarthria. Evaluating ataxia can be challenging considering the volume of disorders and their complex pathologies involving diverse genetic and clinical factors. This is a comprehensive review of the genetic ataxia literature, presenting updated guidelines for differential diagnosis. Age, time course, and family history provide initial guidance for evaluation of ataxia. As genetic testing is increasingly utilized, new genes are discovered and phenotypes for existing disorders are expanded. This review assists physicians by offering a diagnostic roadmap for suspected hereditary ataxia based on the current literature.

The aim of this study was to report relief of optokinetic-triggered vertigo (OKTV) with low-dose gabapentin in three patients with periodic vestibulocerebellar ataxia [episodic ataxia type 4 (EA4); OMIM 606552].
Clinical observations and analysis of video-recorded eye movements were used before and after gabapentin.
Gabapentin relieved vertigo of all three treated patients with EA4, particularly during activities that typically would induce vertiginous symptoms. Two patients reported 8-12 hours of sustained relief after the first 100 mg dose. One has benefited from 100-200 mg TID for 7 years. Video analysis of nystagmus revealed improved target tracking on smooth pursuit and a steadier gaze hold.
Gabapentin effectively relieved the optokinetic-triggered vertigo in our patients with EA4. Mechanisms are postulated in terms of known tight gabapentin binding to the Purkinje cell voltage-gated calcium channel. The observations may offer insight into this rare disease\'s neuropathology. © 2021 International Parkinson and Movement Disorder Society.

The diagnosis of childhood-onset cerebellar ataxia (CA) is often challenging due to variations in symptoms and etiologies. Despite the known regional differences in the prevalence of etiologies underlying CA, the frequency and characteristics of CA in Japan remain unclear. We conducted a questionnaire-based survey to identify the clinical characteristics of childhood-onset CA in the Japanese population.
Questionnaires were sent to 1,103 board-certified pediatric neurologists in Japan from 2016 to 2017. The primary survey requested the number of patients with CA under care, and the follow-up secondary questionnaire requested additional clinical characteristics of the patients.
The primary survey obtained 578 responses (response rate, 52.4%) on 385 patients with CA, including 171 diagnosed and 214 undiagnosed cases (diagnostic rate, 44.4%). The most frequent etiology was dentatorubropallidoluysian atrophy (DRPLA), followed by mitochondrial disorders and encephalitis. The secondary survey obtained the clinical characteristics of 252 cases (119 diagnosed and 133 undiagnosed cases). Multiple logistic regression analysis revealed that a younger age at onset, hearing issues, and short stature were associated with a higher risk of remaining undiagnosed with CA in Japan.
The diagnostic rate of childhood-onset CA in the current study was comparable to those reported in other countries. The high prevalence of autosomal dominant ataxia, especially DRPLA, was a signature of CA in Japan. These data offer insights into the characteristics of childhood-onset CA in the Japanese population.

Spinocerebellar Ataxia Type 7 (SCA7) is a neurodegenerative disorder caused by cytosine-adenine-guanine (CAG) repeat expansion. It is clinically characterized by ataxia and visual loss. To date, little is known about SCA7 cognitive impairments and its relationship with grey matter volume (GMV) changes. The aim of this study was to explore SCA7 patients\' performance in specific components of auditory-verbal neuropsychological tests and to correlate their scores with genetic mutation, severity of ataxia and GMV. We assessed verbal memory and verbal fluency proficiencies in 31 genetically confirmed SCA7 patients, and compared their results with 32 healthy matched volunteers; we also correlated CAG repeats and severity of motor symptoms with performance in the auditory-verbal tests. SCA7 patients exhibited deficiencies in several components of these cognitive tasks, which were independent of motor impairments and showed no relation to CAG repeats. Based on Resonance Images performed in 27 patients we found association between ataxia severity and GMV in \"sensoriomotor\" cerebellum, as well as correlations of impaired verbal memory and semantic fluency scores with GMV in association cortices, including the right parahippocampal gyrus. To our knowledge, this is the first report of deficits in the organization of semantic information and in the evocation of verbal material, as well as greater susceptibility to proactive interference in SCA7 patients. These findings bring novel information about specific cognitive abilities in SCA7 patients, particularly verbal memory and fluency, and their relation with GMV variations in circumscribed brain regions, including association cortices known to have functional relationships with the cerebellum.