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Background: In chronic petrol sniffers, recent exposure to high levels of leaded petrol may give rise to a lead encephalopathy characterised by tremor, chorea, ataxia, hyperreflexia, convulsive seizures, and death. Neurological abnormalities associated with lead encephalopathy involve the cortex, basal ganglia, cerebellum, and brain stem. Objective: To use saccadic eye movement tasks as an experimental tool to determine which CNS changes are associated with chronic petrol sniffing and which with a history of lead encephalopathy, and to what extent these changes are reversible. Methods: Saccade function was assessed in chronic petrol sniffers with a history of lead encephalopathy (encephalopathic sniffers), chronic petrol sniffers who had never suffered lead encephalopathy (chronic sniffers), individuals who had sniffed petrol in the past but had not done so for more than six months (ex-sniffers), and individuals who had never sniffed petrol (non-sniffers). Results: Chronic sniffers showed increased latency of visually guided saccades and antisaccades and increased antisaccade errors which suggested cortical and basal ganglia dysfunction. These abnormalities returned to normal in ex-sniffers. Encephalopathic sniffers showed the same abnormalities as chronic sniffers but with greater severity and additional saccadic signs including dysmetria, gaze evoked nystagmus, and saccade slowing which usually indicate cerebellar and brain stem dysfunction. Conclusions: Chronic petrol abuse is associated with cortical and basal ganglia abnormalities that are at least partially recoverable with abstinence. Additional long term cerebellar and brain stem abnormalities are associated with lead encephalopathy.

To establish whether the DNA expansion linked to spinocerebellar ataxia type 8 (SCA 8) is associated with ataxia in Scotland; to clarify the range of associated clinical phenotypes; and to compare the findings with previous reports.DNA was screened from 1190 anonymised controls, 137 subjects who had tested negative for Huntington's disease, 176 with schizophrenia, and 173 with undiagnosed ataxia. Five unrelated ataxic patients with the SCA 8 expansion and a sixth identified subsequently had clinical and psychometric assessment; the clinical features were available in a seventh. A systematic search for other reports of SCA 8 was undertaken.Over 98% of SCA 8 CTA/CTG repeat lengths fell between 14 and 40. Repeat lengths over 91 were observed in three healthy controls (0.12%), two patients with suspected Huntington's disease (0.73%), and six ataxic subjects (1.74%; p0.0005 v healthy controls). Repeat lengths over 100 occurred in five ataxic subjects but in only one control. All seven symptomatic subjects with the SCA 8 expansion had a cerebellar syndrome; four had upper motor neurone signs; and 5/6 assessed had cognitive complaints. There was personality change in two and mood disturbance in three. In published reports, SCA 8 repeat lengths over 91 occurred in approximately 0.5% of the healthy population but were over-represented among ataxic patients (3.4%; p0.0001). The predominant clinical phenotype was cerebellar, with pyramidal signs in 50%, and neuropsychiatric features in some cases.SCA 8 expansion is a risk factor for a cerebellar syndrome, often associated with upper motor neurone and neuropsychiatric features. The expansion occurs unexpectedly often in the general population.

Background The occurrence of ataxic polyneuropathy in an endemic area in south west Nigeria has been attributed to exposure to cyanide from cassava foods. However, it has been shown that the prevalence of ataxic polyneuropathy is not high in several communities in the tropics where exposure to cyanide from cassava foods is high. Objectives To determine the incidence of ataxic polyneuropathy in an endemic community, and to compare the intake of cassava foods, exposure to cyanide, and levels of thiols in cases and controls. Methods A cohort of 3167 healthy subjects aged 10 years and over in Ososa, Nigeria, was followed for two years, screened, and examined neurologically. Ataxic polyneuropathy was diagnosed if sensory polyneuropathy and sensory gait ataxia were both present. Controls were selected randomly within 10 year age groups of subjects who screened negative. Intake of cassava foods, exposure to cyanide, concentrations of thiols (glutathione, cysteine, and γ glutamylcysteine) in plasma, and visual evoked potentials were measured. Results Person–years of follow up were 6246 for 1469 male and 1698 female subjects in the cohort. The incidence of ataxic polyneuropathy was 64 per 10 000 person–years (31 for male and 93 for female subjects). Multivariate odd ratios were 0.78 (95% CI 0.23 to 2.61) for intake of the commonest cassava food, and 1.64 (0.56 to 5.09) for concentration of thiocyanate in plasma. The concentration of thiols was less than the reference limits in two controls, but in none of the cases. The latency of P100 was prolonged in 20 cases (69%) compared with 14 controls (42%) (p

Objective: To evaluate the efficacy of a revised technique of percutaneous radiofrequency neurotomy for third occipital headache. Methods: The revisions included using a large gauge electrode, ensuring minimum separation between the three electrode placements, and holding the electrode in place by hand. The revised technique was used to treat 51 nerves in 49 patients diagnosed as suffering from third occipital headache on the basis of controlled diagnostic blocks of the third occipital nerve. The criteria for successful outcome were complete relief of pain for at least 90 days associated with restoration of normal activities of daily living, and no use of drug treatment for the headache. Results: Of the 49 patients, 43 (88%) achieved a successful outcome. The median duration of relief in these patients was 297 days, with eight patients continuing to have ongoing relief. Fourteen patients underwent a repeat neurotomy to reinstate relief, with 12 (86%) achieving a successful outcome. The median duration of relief in these patients was 217 days, with six patients having ongoing relief. Side effects of the procedure were consistent with coagulation of the third occipital nerve and consisted of slight ataxia, numbness, and temporary dysaesthesia. No side effects required intervention, and they were tolerated by the patients in exchange for the relief of headache. Conclusions: Use of the revised procedure greatly improved the rather low success rate previously encountered with third occipital neurotomy. Although the relief of headache is limited in duration, it is profound and can be reinstated by repeat neurotomy. No other form of treatment has been validated for this common form of headache.

Background: Limb ataxia is classically attributed to cerebellar hemispheric lesions, although isolated lesions of the inferior cerebellar peduncle (ICP) in the medulla may also cause this sign. It is still unclear why only some patients with acute cerebellar infarcts in the posterior inferior cerebellar artery (PICA) territory present with limb ataxia. The proximal intracranial posterior circulation (P-PC) territory includes structures fed by the intracranial vertebral arteries (ICVAs): the medulla, supplied by small ICVAs branches, and posterior inferior portion of the cerebellum, fed by PICA. ICP and PICA territory cerebellar infarcts most often occur independently but occasionally occur together. Objective: To identify structures responsible for limb ataxia in acute P-PC brain infarcts correlating clinical and topographical findings. Methods: Sixteen patients (8 women) were included with ages ranging from 30 to 82 years (mean age, 62 years) with isolated acute strokes in the P-PC territory. Results: The cases reported here indicate that limb ataxia in acute P-PC territory infarcts may be associated with a damage to the ICP in the dorsolateral medulla, regardless of a hemispheric cerebellar lesion. In fact among the 9 patients with PICA stroke, limb ataxia was observed only in the 2 patients who also presented a damage to the dorsolateral medulla involving the ICP. Of the 7 patients with isolated dorsolateral medullary infarct, only 5 patients with an ICP damage had limb ataxia. Conclusions: When correlating limb ataxia and acute P-PC infarcts it is important to take in account the entire ICVA territory.

Spinocerebellar ataxia 7 (SCA7) is characterised by cerebellar ataxia and visual loss. The aim of the present study was to elucidate the magnetic resonance imaging (MRI) findings characteristic of patients with SCA7.Twenty patients with SCA (eight SCA3, three SCA6, and nine SCA7) and 20 control subjects underwent an MRI-based volumetric analysis.The pontine volume in patients with SCA7 was decreased by a greater amount than in patients with other types of SCA (p0.01), whereas the cerebellar volume was not different from that in other types of SCA (p0.05). Pontine atrophy was a consistent finding in all patients with SCA7 regardless of the degree of cerebellar atrophy or the severity or duration of illness. In contrast, cerebellar atrophy was not found in those with a short duration of illness or mild ataxia, but became prominent as the severity and duration of illness progressed.Our study suggests that neurodegeneration is ongoing during the life of individuals with SCA7, and that the primary pathology in these individuals involves the brainstem rather than the cerebellum. In addition, pontine atrophy is a prominent, consistent finding in SCA7, and may help in establishing the clinical diagnosis of SCA7.

OBJECTIVE: To determine the prevalence and causation of late onset cerebellar ataxia (LOCA) in south east Wales, United Kingdom. METHODS: A population based study of LOCA was conducted in a defined geographical region with a total population of 742,400. Multiple sources of ascertainment were used to identify all cases prevalent on 1 January 2001. The inclusion criteria were: a predominantly progressive cerebellar ataxia with onset of symptoms at age > or = 18 years; and disease duration of > or = 1 year. Cases with known acquired ataxias, ataxic syndromes with associated prominent autonomic dysfunction and/or atypical parkinsonism suggestive of multiple system atrophy and disorders with ataxia as a minor feature were excluded. RESULTS: We identified 76 index cases of LOCA, of whom 63 were sporadic, idiopathic LOCA (ILOCA) and 13 were familial LOCA, of whom six had either spinocerebellar ataxia type 6, Friedreich's ataxia or dominant episodic ataxia. The mean annual incidence rate for the period 1999-2001 was 0.3/100,000 population/year. The crude prevalence rates were 8.4 per 100,000 (95% CI 7.2 to 11.6) for ILOCA and 1.8 per 100,000 (95% CI 0.8 to 2.7) for inherited LOCA. Of the 54/63 (85.7%) patients with ILOCA who were assessed, mean (SD) age at onset of symptoms was 53.8 (14.1) years (range 19 to 78) with a male:female ratio of 2.1:1. The mean disease duration was 8.7 (6.3) years (range 1 to 31). The most frequent presenting complaint was disturbance in gait (90.7%). One-third had a relatively pure cerebellar syndrome (33.3%) and two-thirds (66.7%) had additional extracerebellar neurological features. The majority (92%) were ambulant but only 9.3% were independently self-caring. CONCLUSION: This population based study provides insight into LOCA within a defined region and will inform decisions about the rational use of healthcare resources for patients with LOCA.

Objective: To investigate a comprehensive battery of neurophysiological tests for objective evaluation of sensory neuropathies including fibre type involvement and severity, and to determine the relation between neurophysiological data and clinical examination. Methods: 45 patients referred for sensory neuropathy were studied using a standardised clinical evaluation of large and small fibre symptoms and an original neurophysiological battery. Clinical evaluation included: assessment of tactile, vibratory, and pin sensation; tendon reflexes; toe position sense; ataxia score; pain level; and presence of trophic, vasomotor, or sudomotor abnormalities. The neurophysiological battery included: recording of large fibre and small fibre components of the sural sensory nerve action potential; somatosensory evoked cortical potentials and soleus H reflex following tibial nerve electrical stimulation; laser evoked potentials following Nd:YAG laser stimulation of the foot; and plantar sympathetic skin response to median nerve stimulation. Neuropathy was classified according to the predominantly affected fibre type, and a severity score was established based on clinical and neurophysiological abnormalities. Results: On clinical examination there were 22 patients with large fibre sensory neuropathy (LFSN), 18 with mixed sensory neuropathy (MSN), and five with small fibre sensory neuropathy (SFSN). Neurophysiological classification identified 25 patients with LFSN, 13 with MSN, and seven with SFSN. Clinical and neurophysiological classifications and severity scores were correlated, whatever the type of neuropathy. Conclusions: The correlation between clinical examination and the results of an original neurophysiological test battery offers a comprehensive clinical and neurophysiological approach to the objective assessment of peripheral neuropathies according to fibre type involvement and overall severity.

Objective: Spinocerebellar ataxia type 2 (SCA2) has been reported as the commonest dominant hereditary ataxia in India. However, India is an ethnically and religiously diverse population. Previous studies have not clearly indicated exact ethnic and religious origins, and must therefore be interpreted with caution. The purpose of this study was to determine the prevalence of different SCA mutations in a relatively homogeneous population from eastern India. Methods: We identified 28 families with autosomal dominant cerebellar ataxia from eastern India. Each underwent full clinical evaluation and were analysed for the presence of SCA1, SCA2, SCA3, SCA6, SCA7, SCA8, SCA12, and SCA17 mutations. In addition, haplotype analysis was carried out in seven of the 16 families with SCA2. Results: Seven patients from four (14%) families were positive for an expansion in SCA1 and 26 patients from 16 (57%) families were positive for an expansion in SCA2. No mutations were detected in the remaining eight families (29%). Most of the SCA1 and SCA2 families were Hindu from the state of Bihar. Five out of 26 SCA2 patients in this study did not have slow saccades. In addition, four of seven SCA1 patients had slow saccades. We found an association between the SCA2 CAG repeat expansion and the 285 base pair (bp) allele of microsatellite marker D12S1672, and also data supportive of the association between the expansion and the 225 bp allele of D12S1333, which has been previously described. Conclusions: We conclude that (1) although slow ocular saccades are highly suggestive of SCA2, that they are not universal, nor are they exclusive to this disorder and (2) SCA2 is likely to be the commonest dominant ataxia in eastern India, with further evidence for a founder effect.

Background: Gluten ataxia is an immune mediated disease, part of the spectrum of gluten sensitivity, and accounts for up to 40% of cases of idiopathic sporadic ataxia. No systematic study of the effect of gluten-free diet on gluten ataxia has ever been undertaken. Objective: To study the effect of gluten-free diet on patients presenting with ataxia caused by gluten sensitivity. Methods: 43 patients with gluten ataxia were studied. All were offered a gluten-free diet and monitored every six months. All patients underwent a battery of tests to assess their ataxia at baseline and after one year on diet. Twenty six patients (treatment group) adhered to the gluten-free diet and had evidence of elimination of antigliadin antibodies by one year. Fourteen patients refused the diet (control group). Three patients had persistently raised antigliadin antibodies despite adherence to the diet and were therefore excluded from the analysis. Results: After one year there was improvement in ataxia reflected in all of the ataxia tests in the treatment group. This was significant when compared with the control group. The diet associated improvement was apparent irrespective of the presence of an enteropathy. Conclusions: Gluten ataxia responds to a strict gluten-free diet even in the absence of an enteropathy. The diagnosis of gluten ataxia is vital as it is one of the very few treatable causes of sporadic ataxia.