Incidence of peripheral neuropathy and cerebellar ataxia in chronic alcoholics

Persistence of cerebellar ataxia during chronic ethanol exposure is associated with epigenetic up-regulation of Fmr1 gene expression in rat cerebellum

BACKGROUND

Alcohol intoxication produces ataxia by affecting the cerebellum, which coordinates movements. Fragile X mental retardation (FMR) protein is a complex regulator of RNA and synaptic plasticity implicated in fragile X-associated tremor/ataxia syndrome, which features ataxia and increased Fmr1 mRNA expression resulting from epigenetic dysregulation of FMRP. We recently demonstrated that acute ethanol-induced ataxia is associated with increased cerebellar Fmr1 gene expression via histone modifications in rats, but it is unknown whether similar behavioral and molecular changes occur following chronic ethanol exposure. Here, we investigated the effects of chronic ethanol exposure on ataxia and epigenetically regulated changes in Fmr1 expression in the cerebellum.

METHODS

Male adult Sprague-Dawley rats were trained on the accelerating rotarod and then fed with chronic ethanol or a control Lieber-DeCarli diet while undergoing periodic behavioral testing for ataxia during ethanol exposure and withdrawal. Cerebellar tissues were analyzed for expression of the Fmr1 gene and its targets using a real-time quantitative polymerase chain reaction assay. The epigenetic regulation of Fmr1 was also investigated using a chromatin immunoprecipitation assay.

RESULTS

Ataxic behavior measured by the accelerating rotarod behavioral test developed during chronic ethanol treatment and persisted at both the 8-h and 24-h withdrawal time points compared to control diet-fed rats. In addition, chronic ethanol treatment resulted in up-regulated expression of Fmr1 mRNA and increased activating epigenetic marks H3K27 acetylation and H3K4 trimethylation at 2 sites within the Fmr1 promoter. Finally, measurement of the expression of relevant FMRP mRNA targets in the cerebellum showed that chronic ethanol up-regulated cAMP response element binding (CREB) Creb1, Psd95, Grm5, and Grin2b mRNA expression without altering Grin2a, Eaa1, or histone acetyltransferases CREB binding protein (Cbp) or p300 mRNA transcripts.

CONCLUSIONS

These results suggest that epigenetic regulation of Fmr1 and subsequent FMRP regulation of target mRNA transcripts constitute neuroadaptations in the cerebellum that may underlie the persistence of ataxic behavior during chronic ethanol exposure and withdrawal.

Central Nervous System Correlates of "Objective" Neuropathy in Alcohol Use Disorder

BACKGROUND

Among the neurological consequences of alcoholism is peripheral neuropathy. Relative to human immunodeficiency virus (HIV) or diabetes-related neuropathies, neuropathy associated with alcohol use disorders (AUD) is understudied. In both the diabetes and HIV literature, emerging evidence supports a central nervous system (CNS) component to peripheral neuropathy.

METHODS

In seeking a central substrate for AUD-related neuropathy, the current study was conducted in 154 individuals with AUD (43 women, age 21 to 74 years) and 99 healthy controls (41 women, age 21 to 77 years) and explored subjective symptoms (self-report) and objective signs (perception of vibration, deep tendon ankle reflex, position sense, 2-point discrimination) of neuropathy separately. In addition to regional brain volumes, risk factors for AUD-related neuropathy, including age, sex, total lifetime ethanol consumed, nutritional indices (i.e., thiamine, folate), and measures of liver integrity (i.e., γ-glutamyltransferase), were evaluated.

RESULTS

The AUD group described more subjective symptoms of neuropathy and was more frequently impaired on bilateral perception of vibration. From 5 correlates, the number of AUD-related seizures was most significantly associated with subjective symptoms of neuropathy. There were 15 correlates of impaired perception of vibration among the AUD participants: Of these, age and volume of frontal precentral cortex were the most robust predictors.

CONCLUSIONS

This study supports CNS involvement in objective signs of neuropathy in AUD.

Perspectives on fronto-fugal circuitry from human imaging of alcohol use disorders

Descriptions of the cognitive functions affected by alcohol use disorders (AUD) often highlight dysfunction of executive processes such attention, inhibitory control, working memory, and cognitive flexibility. Such complex cognitive functions have historically been ascribed to the prefrontal cortex. AUD, however, disrupts extensive areas of the brain. Structural and functional MRI studies suggest a central role for degradation of circuitry originating in the prefrontal cortex including nodes in widespread brain regions. This review features fronto-fugal circuits affected by AUD including frontocerebellar, frontolimbic, and frontostriatal networks and their relations to the salient, enduring, and debilitating cognitive and motor deficits reported in AUD. This article is part of the Special Issue entitled "Alcoholism".

Peripheral systems: neuropathy

Long-term, excessive consumption of alcoholic beverages produces a peripheral neuropathy with symptoms of decreased superficial sensation, hyperalgesia, and weakness. Alcoholic neuropathy is characterized by axonal degeneration with reduced density of both small and large fibers and axonal sprouting. Electrophysiologic studies reveal a marked reduction in the amplitude of sensory potentials and moderate slowing of nerve conduction, mainly in the lower extremities. Dietary deficiency of vitamins, which are often associated with chronic alcoholism, can contribute to the pathogenesis. Recent studies using animal models have identified several mechanisms by which ethanol impacts peripheral nerve function. Ethanol can exert direct neurotoxic effects on peripheral nerves via its metabolite acetaldehyde and by enhancing oxidative stress. Ethanol activation of protein kinase Cε signaling in primary afferent nociceptors plays an important role in lowering nociceptive threshold. Further, ethanol causes cytoskeletal dysfunction and inhibits both anterograde and retrograde axonal transport. Alcoholic neuropathy is potentially reversible and treatments include abstinence from alcoholic beverages and consumption of a nutritionally balanced diet supplemented with B vitamins. However, response to these treatment strategies can be variable, which underscores the need for novel therapeutic strategies. In this review, we provide an overview of the clinical findings and insights on molecular mechanisms from animal models.

Characterization of cerebellar ataxia in chronic alcoholics using the International Cooperative Ataxia Rating Scale (ICARS)

BACKGROUND

Alcoholism is the most common cause of cerebellar dysfunction, yet estimates of the incidence of alcoholic cerebellar degeneration (ACD) vary greatly, with differences in methodologies contributing to these disparate findings. This study set out to characterize the frequency and pattern of clinical signs of ACD in an alcoholic group using the International Cooperative Ataxia Rating Scale (ICARS).

METHODS

We compared the performance of 49 alcoholics and 29 control participants. The relative contributions of demographic and alcohol consumption variables to ICARS scores in the alcoholic group were also examined.

RESULTS

The alcoholic group demonstrated significantly poorer performance on all of the ICARS subscales as compared with the control group. Within the alcoholic group, performance was more impaired on the speech scale than on all of the other scales, except the lower limb component of the kinetic scale, and less impaired on the oculomotor scale compared with all other scales. Years of heavy drinking and lifetime alcohol consumption correlated with total ICARS scores; however, maximum daily consumption was actually negatively correlated with ICARS scores. Of the alcohol history variables, years of heavy drinking was the best predictor of total ICARS scores, making a 19% unique contribution, followed by the period of abstinence from alcohol, which uniquely contributed 7% of the variance. There were high correlations between age and male gender and the alcohol consumption variables; however, age and gender were still found to uniquely contribute 5 and 7% respectively to the variance in total ICARS scores.

CONCLUSIONS

ACD may affect up to two-thirds of chronic alcoholics. Assessing the number of years an individual has been drinking beyond a certain threshold can give a good indication of the likelihood of ACD. Age, gender, and the source of the clinical sample may significantly contribute to the prevalence of ACD and require further detailed investigation.

Persistent but less severe ataxia in long-term versus short-term abstinent alcoholic men and women: a cross-sectional analysis

BACKGROUND

Disturbed gait and balance are among the most consistent and salient sequelae of chronic alcoholism. Results of small sample longitudinal investigations have provided evidence that partial recovery of gait and balance functions in alcoholics may be achieved with abstinence. However, abstinence durations reported have been limited, and their power and generalizability have suffered from small sample sizes.

METHODS

In this study, we employed a cross-sectional approach to assess gait and balance functions in short-term (6 to 15 weeks) abstinent alcoholics (STAA; n = 70) and long-term (minimum 18 months, mean = 7.38 years) abstinent alcoholics (LTAA; n = 82). STAA and LTAA did not differ with respect to lifetime alcohol consumption, family drinking density, or years of education. In addition, we examined the effects of gender and alcohol use variables.

RESULTS

Our main findings were: (i) persistent disturbed gait and balance in STAA and disturbed standing balance in LTAA; (ii) overall less impaired performance of LTAA compared with STAA on gait and balance measures; and (iii) worse performance of STAA (but not LTAA) women, compared with men, on standing balance without visual control.

CONCLUSIONS

Our results suggest that alcoholics' gait and balance can continue to recover with long abstinence from alcohol, but that deficits persist, especially in eyes-closed standing balance. In addition, our results are consistent with more severe alcohol-induced ataxia in women than in men but suggest that with extended abstinence, women recover gait and balance function to a level comparable with men.

A double-blind, randomized, placebo-controlled trial of intravenous L-ornithine-L-aspartate on postural control in patients with cirrhosis

INTRODUCTION

Hepatic encephalopathy (HE) is a complication of liver disease. Several treatments have been introduced but only L-ornithine-L-aspartate (LOLA) shows proven efficacy. This double-blind, randomized, placebo-controlled trial evaluated the effect of LOLA on postural control in cirrhotics.

METHODS

Forty patients were randomized to either LOLA or a placebo. HE was evaluated by psychometric testing (PSE Syndrome Test) and critical flicker frequency (CFF). Posturography [equilibrium score (ES)] provided information regarding postural control. Peripheral blood was analysed for ammonia concentration (NH(3)) and the partial pressure of ammonia (pNH(3)).

RESULTS

Both groups were comparable regarding baseline variables. Posturography and PSE Syndrome Test improved in both groups; improvement was greater in the LOLA group (ES: 5.3%; PSE: 1.9) compared with the placebo (ES: 3.9%; PSE: 1.3) but did not reach significance (ES: P=0.3; PSE: P=0.5). CFF remained unchanged during treatment and between groups (P=NS). NH(3) decreased in the LOLA group (Delta: -15 micromol/L) and slightly increased in the placebo group (Delta: 11.1 micromol/L), but the differences did not reach statistical significance (P=0.07). pNH(3) remained largely unchanged (LOLA Delta: -1.2 x 10(-5) mmHg vs. placebo Delta: -0.3 x 10(-5) mmHg; P=0.21).

CONCLUSION

In the LOLA group, an improvement of posturographic control and PSE Syndrome Test was observed, but a similar improvement was also achieved by the placebo. In LOLA, ammonia levels tended to decrease while they tended to increase in the placebo group. LOLA might augment the improvement achieved by intravenous fluids alone but a larger cohort will be needed to show this effect with statistical significance.

Mechanisms of postural control in alcoholic men and women: biomechanical analysis of musculoskeletal coordination during quiet standing

BACKGROUND

Excessive sway during quiet standing is a common sequela of chronic alcoholism even with prolonged sobriety. Whether alcoholic men and women who have remained abstinent from alcohol for weeks to months differ from each other in the degree of residual postural instability and biomechanical control mechanisms has not been directly tested.

METHOD

We used a force platform to characterize center-of-pressure biomechanical features of postural sway, with and without stabilizing conditions from touch, vision, and stance, in 34 alcoholic men, 15 alcoholic women, 22 control men, and 29 control women. Groups were matched in age (49.4 years), general intelligence, socioeconomic status, and handedness. Each alcoholic group was sober for an average of 75 days.

RESULTS

Analysis of postural sway when using all 3 stabilizing conditions versus none revealed diagnosis and sex differences in ability to balance. Alcoholics had significantly longer sway paths, especially in the anterior-posterior direction, than controls when maintaining erect posture without balance aids. With stabilizing conditions the sway paths of all groups shortened significantly, especially those of alcoholic men, who demonstrated a 3.1-fold improvement in sway path difference between the easiest and most challenging conditions; the remaining 3 groups, each showed a approximately 2.4-fold improvement. Application of a mechanical model to partition sway paths into open-loop and closed-loop postural control systems revealed that the sway paths of the alcoholic men but not alcoholic women were characterized by greater short-term (open-loop) diffusion coefficients without aids, often associated with muscle stiffening response. With stabilizing factors, all 4 groups showed similar long-term (closed loop) postural control. Correlations between cognitive abilities and closed-loop sway indices were more robust in alcoholic men than alcoholic women.

CONCLUSIONS

Reduction in sway and closed-loop activity during quiet standing with stabilizing factors shows some differential expression in men and women with histories of alcohol dependence. Nonetheless, enduring deficits in postural instability of both alcoholic men and alcoholic women suggest persisting liability for falling.

Postural control in patients with liver cirrhosis: a posturographic study

BACKGROUND

Ataxia has been suggested in the literature to be a symptom of hepatic encephalopathy (HE), but so far has not been objectively quantified. In this study, we wanted to objectively quantify ataxia in patients with liver cirrhosis.

METHODS

One hundred and seven patients with liver cirrhosis were tested for postural control using posturography and compared with 25 controls. For quantification of HE, we used the number connection tests A and B, ammonia levels (NH3), and the partial pressure of ammonia in the arterial blood (pNH3).

RESULTS

Patients showed an impaired postural control compared with controls. Patients with Child C cirrhosis had lower scores in the posturography than those with Child A or B cirrhosis. Patients with alcohol-induced (AIC) Child B cirrhosis achieved lower scores in the posturography than those with non-alcohol-induced (NAIC) Child B cirrhosis. Patients with AIC Child C had lower scores than the corresponding NAIC patients, although this did not reach statistical significance. In the NAIC group Child C patients, in the AIC group Child B and C patients had lower scores than the controls. Patients with abnormal results in the number connection tests, as well as those with high NH3 and pNH3 levels showed worse postural control than those with normal results.

CONCLUSION

Patients with cirrhosis have an impaired postural control compared with controls and this impairment deteriorates with progression of liver disease. HE as well as past alcohol abuse contribute to the pathogenesis of ataxia in liver cirrhosis and past alcohol abuse leads to an earlier and more pronounced manifestation of ataxia in the affected patients.

Neurological complications of alcohol usage

The relationships between alcohol usage and a number of neurological syndromes are reviewed. These are often complex and incompletely understood. Multiple rather than single factors are the rule rather than the exception. The correct diagnosis may be missed particularly where the aetiological role of alcohol is overlooked. Multiple diagnoses are not uncommon. Issues of differential diagnosis and diagnostic procedures are discussed. Management, including a number of its pitfalls, is outlined.

Relationships of job hazards, lack of knowledge, alcohol use, health status and risk taking behavior to work injury of coal miners: a case-control study in India

Objective is to assess the relationships of job hazards, individual characteristics, and risk taking behavior to occupational injuries of coal miners. This case-control study compared 245 male underground coal miners with injury during the previous two-year period with 330 matched controls without injury during the previous five years. Data were collected via face-to-face interview and analyzed using the conditional logistic model. Handling material, poor environmental/working conditions, and geological/strata control- related hazards were the main risk factors: adjusted ORs 5.15 (95% CI 2.42-10.9), 2.40 (95% CI 1.29-4.47), and 2.25 (95% CI 1.24-4.07) respectively. Their roles were higher among the face-workers than among the non-face-workers. No formal education, alcohol consumption, disease, big-family, and risk-taking behavior were associated with injuries (2.36</=ORs</=10.35), and the findings were similar for both face and non-face workers. Prevention should focus on handling material, poor environmental condition, especially addressing workers with no formal education, alcohol consumption, disease, big family size, and risk-taking behavior.

Large and small fiber neuropathy in chronic alcohol-dependent subjects

The aim of the present study was to evaluate the occurrence of large and small fiber neuropathy among alcohol-dependent subjects and to correlate neuropathy with the pattern of alcohol abuse, age of the subjects, nutritional status, and biochemical parameters. The study sample comprised 98 consecutive alcohol-dependent subjects without signs of malnutrition treated for detoxification voluntarily in the specialized unit of the Athens University Psychiatric Clinic in an inpatient basis. Polyneuropathy (PN) was graded using the neuropathy symptoms score and neurologic disability score, conduction velocity studies, and quantitative sensory tests. Seventy-seven men and 21 women aged 27-70 years took part in the study. PN was diagnosed in 57 subjects (58.2%). PN of both large and small fibers was found in 25 patients (25.5%); exclusively small fiber neuropathy was observed in 12 (12.2%) and exclusively large fiber neuropathy in 20 patients (20.4%). Neuropathy was significantly correlated with the age of the subjects, duration of alcohol abuse, liver dysfunction, macrocytosis, and blood sugar levels upon admission. PN was significantly more frequent in males than in females. The two groups of exclusively large and exclusively small fiber neuropathy did not differ significantly in any clinical and laboratory parameter. Subclinical neuropathy (stage 1) was observed in 11.2%, which also did not differ significantly in any clinical and laboratory parameter from the stage 2 PN group subjects. Our findings indicate the direct toxic effect of alcohol on peripheral nerve fibers as the main etiologic factor of alcoholic PN. Long-standing hyperglycemia may be another contributing factor. Impaired vitamin B(12) utilization may be also involved.

Effect of vision, touch and stance on cerebellar vermian-related sway and tremor: a quantitative physiological and MRI study

Postural balance is impaired in individuals with pathology of the anterior superior vermis of the cerebellum. Chronic alcoholism, with its known vermian pathology, provides a viable model for studying the relationship between cerebellar pathology and postural stability. Decades of separate study of recovering alcoholics and post-mortem neuroanatomical analysis have demonstrated vermian pathology but few studies have used quantitative posturography, acquired concurrently with quantitative neuroimaging, to establish whether this brain structure-function relationship is selective in vivo. Here, 30 healthy men and 39 chronic alcoholic men, abstinent from alcohol for several months, underwent MRI for volumetric quantitation of the cerebellar vermis and three comparison brain regions, the cerebellar hemispheres, supratentorial cortex and corpus callosum. All subjects also participated in an experiment involving a force platform that measured sway path length and tremor during static standing balance under four sensory conditions and two stance conditions. Three novel findings emerged: (i) sway path length, a physiological index of postural control, was selectively related to volume of the cerebellar vermis and not to any comparison brain region in the alcoholics; (ii) spectral analysis revealed sway prominence in the 2-5 Hz band, another physiological sign of vermian lesions and also selectively related to vermian volume in the alcoholics; and (iii) despite substantial postural sway in the patients, they successfully used vision, touch and stance to normalize sway and reduce tremor. The selective relationship of sway path to vermian but not lateral cerebellar volume provides correlational evidence for functional differentiation of these cerebellar regions. Improvement to virtual normal levels in balance and reduction in sway and tremor with changes in vision, touch and stance provide evidence that adaptive mechanisms recruiting sensorimotor integration can be invoked to compensate for underlying cerebellar vermian-related dysfunction.

Vermal atrophy of alcoholics correlate with serum thiamine levels but not with dentate iron concentrations as estimated by MRI

Chronic alcohol consumption is frequently accompanied by cerebellar degeneration. The exact aetiology of alcoholic cerebellar degeneration is still a matter of debate. The aim of the present study was to investigate whether patients with chronic alcohol consumption exhibit a decrease in dentate nuclei intensity as measured by MRI, and if so, whether this decrease correlates with cerebellar atrophy as revealed by MR imaging or with clinical signs of cerebellar ataxia. A decrease in dentate nuclei intensity would indirectly indicate that iron accumulation, and therefore, oxidative stress may play a role in alcoholic cerebellar degeneration. MRI of 45 alcoholics and 44 age and sex-matched healthy control subjects was performed using a 3D-T1-weighted fast low angle shot (FLASH) echo sequence. Signal intensities of the dentate nuclei and cerebellar white matter were bilaterally measured. Planimetric measurements of cerebellar size were performed using a 3D-T1-weighted magnetization prepared rapid acquisition gradient echo (MPRAGE) sequence. Results demonstrated that dentate nuclei intensity was not significantly decreased in patients with chronic alcohol consumption (mean +/- SD signal intensity 65.36 +/- 13.0) if compared with control subjects (mean +/- SD signal intensity 68.95 +/- 9.4) (p = 0.15). Dentate nuclei intensity did not correlate with cerebellar size neither in control subjects nor in alcoholics. In contrast, vitamin B1 level correlated with cerebellar size in alcoholics even if the vitamin B1 concentration was within normal values (r = 0.344, p = 0.028). These results support the view that thiamine deficiency rather than direct neurotoxic effects of alcohol is the main causative factor for the development of alcoholic cerebellar degeneration.

Alcohol Affects Eye Movements Essential for Visually Guided Stepping

BACKGROUND

To understand how and why alcohol intoxication affects visually guided stepping, the eye movements and performance of 6 subjects (aged 22-35 years) were monitored as they progressed along a pathway of 18 irregularly placed stepping stones before and after consumption of an acute oral dose of alcohol.

METHODS

Horizontal eye movements were measured with infrared reflectometry; footfall on or off target was monitored via copper fabric soles stuck to subjects' footwear. Breath alcohol concentration was monitored with an Alco-Sensor III breathalyzer.

RESULTS

After alcohol loading, both locomotor and oculomotor deficits were evident. All subjects increased their step cycle duration-with prolonged stance, swing, and double support phases-and occasionally missed footfall targets. A large proportion of saccades made to fixate successive stepping stones were inaccurate and were accompanied by one or more corrective saccades. These problems with looking and stepping to footfall targets tended to occur together and were comparable to those seen previously in cerebellar patients undertaking the same task.

CONCLUSIONS

The fact that healthy subjects acutely intoxicated by alcohol show symptoms of cerebellar dysfunction suggests that alcohol acutely and adversely affects the cerebellar contribution to performance of visually guided movements.

Individual characteristics in occupational accidents due to imbalance: a case-control study of the employees of a railway company

BACKGROUND

Falls are frequent occupational accidents, and are responsible for a significant amount of lost working time and, more importantly, for a high mortality. The factors involved in falling mechanisms can be of external or individual origin, the latter being less well identified.

AIMS

To assess the relations between certain individual characteristics and occupational accidents due to imbalance.

METHODS

A total of 427 male employees, who had been victims of at least one occupational accident with sick leave due to imbalance (cases) and 427 controls were recruited among the employees of a large French railway company. A standardised questionnaire on life conditions and professional factors, and a description of the accidents was filled in by an occupational physician for each subject.

RESULTS

Some job categories were more affected by a specific release mechanism of work related falls. Certain individual characteristics such as smoking, alcohol consumption, inactivity, sleep disorders, and request for a job change were correlated with the occurrence of occupational accidents. Sick leaves of eight days or over were more frequent in older and overweight injured workers. Some lesions were linked with the specific fall released mechanisms.

CONCLUSIONS

Individual characteristics can increase the risk of occupational accidents, especially falling. This study identified subjects most at risk on whom prevention related to working conditions and falls could be focused.

Falls and working individuals: role of extrinsic and intrinsic factors

Falls are frequent occupational accidents involving workers and lead to important social and economic consequences both for the individual and for the employer. Different factors can modify balance control and lead to falling, especially environment-related and individual factors. The literature would appear to indicate that there have been few studies on the intrinsic factors involving the mechanisms of generating falls. This review determines the main factors involved in the mechanisms of falling, whether related to the environment, work or the individual. Knowledge of the extrinsic and intrinsic factors contributing to the fall could allow securer environment planning and occupational conditions for employers, and the use of balance rehabilitation methods for individuals to reduce the risk of falls.

Postural control and lifetime alcohol consumption in alcohol-dependent patients

OBJECTIVES

The aim of this study was to examine the relationship between alcohol consumption and postural control in alcohol-dependent patients.

MATERIAL AND METHODS

Posturographic measurements were performed in 82 abstinent patients and in 54 healthy controls. The findings in the patients were compared with those in the controls as well as with the daily alcohol consumption, the consumption during 6 months before the admission for alcohol withdrawal therapy and the estimated lifetime alcohol consumption.

RESULTS

Postural control was impaired in alcohol-dependent patients compared to healthy controls. This impairment was related with the lifetime alcohol consumption, but not with the alcohol consumption per day and prior to admission, respectively. Comparing healthy controls, and alcohol-dependent patients with an estimated lifetime alcohol consumption of < 1000 kg and > or = 1000 kg revealed a significant increase in 6 of 8 sway parameters. Furthermore, the lifetime alcohol consumption increased significantly from patients with normal posturographic and clinical findings to those with abnormalities in both examinations.

CONCLUSION

This study suggests that postural imbalance in abstinent alcohol-dependent patients is related to the lifetime alcohol consumption.

Assessment of neurotoxicity from potential medications for drug abuse: ibogaine testing and brain imaging

New technologies utilized for monitoring brain function can be more sensitive in the assessment of desired or undesired pharmacological effects than can clinical examination. Nonetheless, careful case-by-case analysis is required to determine to what extent a change detected with a sensitive imaging modality will have clinical significance. Whereas in some instances the technology may suggest a subclinical condition years before clinical signs develop, in other instances changes seen may be compensated for through system reserves, redundancy, or plasticity. Furthermore, simultaneous application of several assay instruments, including behavioral, electrophysiological, and nuclear medicine approaches, may be appropriate and useful for establishing correlations between changes in specific aspects of brain function and amelioration of a disease (drug abuse disorder) or its sequelae. In the example of ibogaine, a testing strategy was developed to assess human subjects for possible changes in cerebellar function (that were suggested by preclinical findings indicating subtle damage). Thus, subjects may be tested for subclinical alterations during and immediately following a clinical trial. This "harbinger of toxicity" approach would provide clinicians the critical data necessary for appropriate follow-up of subjects as well as the propriety of continuance of the clinical trials within the ibogaine project.

Effects of a low alcohol dose on static balance, fine motor activity, and mental performance

The effects of a single low alcohol dose (men 0.54 g and women 0.44 g alcohol per kg body weight) were measured by static balance, fine motor activity, and mental performance. In 10 healthy volunteers balance was registered by a temporally and spatially high resolution platform measuring the center of foot pressure and a three-dimensional coordination measurement system. Fine motor activity and mental performance were tested with selected experiments from the NES2 (Neurobehavioral Evaluation System) neuropsychological test battery. Changes of bipedal and monopedal balance could be detected after the alcohol consumption. Neither the fine motor activity nor the mental performance test demonstrated significant effects. Thus, the static balance test proved to be a sensitive, fast, and atraumatic method to identify slight neurotoxic disturbances.

Randomized perturbed posturography in abstinent chronic alcoholics

Equilibrium is maintained by visual, proprioceptive and vestibular afferent influx, central coordination and motor efferents. Eleven male abstinent chronic alcoholic volunteers aged 44-65 years (mean 57 years) were investigated by randomized perturbed posturography. They had all been long time heavy drinkers. Ocular smooth pursuit and visual suppression of the vestibulo-ocular reflex showed abnormalities in a previous study, but they had no signs or symptoms of polyneuropathy. The current study demonstrated larger (but generally not significantly so) sway areas, and in all tests on the randomly moving support surface the sway velocities were significantly larger than in the controls. It is concluded that randomized perturbed posturography is valuable in dysequilibrium assessment in chronic alcoholics.

Covariates of human peripheral nerve function: I. Nerve conduction velocity and amplitude

A systematic investigation of covariates of nerve conduction measures was performed on data collected by the U.S. Centers for Disease Control. Nerve conduction velocity and amplitude were obtained for the median motor, median sensory, ulnar sensory, peroneal motor, and sural sensory nerves on 4,462 subjects. The magnitude of effect of skin temperature, height, body mass index, age, race, place of military service, smoking status, alcohol consumption, income, and EMG examiner was estimated for all 10 conduction outcomes. The major covariates were skin temperature, height, and examiner. Covariates with smaller but not unimportant effects on conduction outcomes were age, race, smoking status, and income. Alcohol consumption was associated with only small effects on conduction measures. These results provide an empirical basis for selection of variables to control in studies employing nerve conduction measures.

Covariates of human peripheral nerve function: III. Effects of reported drinking

A cross-sectional epidemiologic study of the relationship between alcohol consumption and peripheral nerve function was performed using data from a cohort of 4462 male Vietnam-era Army veterans selected independently of either alcohol consumption history or clinical disorders associated with excessive alcohol use. Self-reported alcohol consumption, expressed as current drinking intensity (drinks per month), was the primary measure of alcohol use. The dependent variables were: (a) conduction velocity and amplitude of the median motor, median sensory, ulnar sensory, peroneal motor, and sural sensory nerves; (b) vibrotactile and thermal thresholds of the index finger and great toe. Drinkers who reported consuming < 180 drinks per month had, in general, slightly faster mean nerve conduction velocities, slightly greater evoked response amplitudes, and slightly lower vibrotactile thresholds than did both never drinkers and drinkers reporting consuming more than 179 drinks per month. The heaviest drinking category (> 179 drinks/month) had slightly slower mean conduction velocities and slightly smaller mean amplitudes than all other drinking categories. No consistent associations were observed between thermal thresholds and alcohol consumption. These results suggest that consuming up to 6 drinks per day alone does not cause slowed nerve conduction velocity, diminished amplitude of the evoked response, or elevated sensory thresholds in 35- to 45-year-old men.

Innervation of normal human sural and optic nerves by noradrenaline- and peptide-containing nervi vasorum and nervorum: effect of diabetes and alcoholism

Histochemical, immunohistochemical and neurochemical techniques were used to examine the innervation of epineurial nerve sheaths and fascicular nerve bundles of human sural and optic nerves from controls and patients with peripheral neuropathy due to diabetes or alcoholism. The normal distribution of autonomic nerves in both nerve trunk sheaths consisted of a dense innervation by noradrenaline (NA)-containing nerves of the vasa nervorum, together with some fibres in the nervi nervorum. Intrafascicular NA-containing nerves were only present in the sural nerve. Vasoactive intestinal polypeptide (VIP)- and neuropeptide Y (NPY)-containing nerves also innervated the vasa nervorum and nervi nervorum of the nerve sheaths, although their density was considerably less. Substance P (SP)-containing nerves were sparse and primarily intrafascicular. Neurochemical assays for NA, VIP, NPY and SP in fascicular and epineurial preparations from the sural and optic nerves confirmed the light microscopical observations. Post mortem delay significantly affected the NA levels in the sural nerve but not in the optic nerve while the NA fascicular/epineurial ratio for the sural nerve was independent of this factor. Age, sex and the presence of alcohol at time of death had no effect on transmitter levels in normal sural nerves. In the optic nerve fascicles NA levels were higher in females than in males. In patients with peripheral neuropathy there was a significant reduction in the SP fascicular/epineurial ratio in both the optic nerve, which was histologically normal, and in the sural nerve, where there was evidence of neuropathy. The NA fascicular/epineurial ratio was also significantly reduced in the sural nerve from patients with peripheral neuropathy with a possible greater effect in diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)

Motoric signs of CNS dysfunction associated with alcohol and cocaine withdrawal

Measures of hand tremor and body sway were recorded from 6 alcohol-dependent (AD) and 16 cocaine-dependent (CD) patients after 1, 3, and 12 weeks of verified abstinence. The same measures were recorded from 15 nonpatient control subjects after comparable intervals. Hand tremor was transduced via an accelerometer. Body sway was transduced by a force-sensitive platform. Analyses revealed different patterns of motoric dysfunction in the AD and CD groups. AD patients exhibited enhanced hand tremor during a pointing task and enhanced body sway. Both of these abnormalities remitted with continued abstinence. CD patients exhibited enhanced and unchanging levels of resting tremor across the first 12 weeks of abstinence, but they had normal levels of body sway and action tremor. These results are interpreted as reflecting a subclinical cerebellar dysfunction in recovering AD patients, and a subclinical extrapyramidal dysfunction in the CD counterparts.

Postural sway in children from pedigrees exhibiting a high density of alcoholism

A total of 98 children participated in a study of the neurobehavioral characteristics of individuals from pedigrees in which there was a high density of alcoholism. Two groups of children were evaluated (High and Low Risk) using a sensitive movement platform and a variety of methods to challenge the motor system. High-Risk children showed a greater decrement in postural steadiness when visual input was removed than did Low-Risk children. Additionally, the monopedal stances revealed hemispheric differences in postural sway as a function of risk status. The amount of sway exhibited was correlated with the latency of P300 recorded using a visual task. Both appear to be indicators of neuropathological changes. The present results suggest that postural sway may be a neurobehavioral marker for alcoholism risk.

Effect of alcohol measured by dynamic posturography

Thirteen healthy male volunteers aged 21-42 years (mean 27 years) were assessed by dynamic posturography before and after ingestion of alcohol. Each subject was given 0.6 g alcohol per kg body weight in fruit juice to be drunk within 10 min. Alcohol levels in blood samples at 15, 45 and 75 min after ingestion were assessed by gas chromatography. Posturographic measurements were conducted at 30 and 60 min after alcohol administration. Dynamic posturography comprises a sensory organization part in which the support surface and visual surround are either stable or referenced to the patient's sway and the test conditions are eyes open or eyes closed. In a movement coordination part the platform makes active movements. Alcohol levels were 0.40% (SD 0.14) after 45 min and 0.51% (SD 0.14) at 75 min. All subjects presented positional alcohol nystagmus and gaze nystagmus after 45 min. In the sensory organization part of the dynamic posturography in test conditions with eyes closed and the head in neutral position, both with stable (p less than 0.039) and sway-referenced platform (p less than 0.017), alcohol effects were found. In the test condition with sway referenced platform and stable visual surround the effect of alcohol was close to significance (p less than 0.069). When the head was tilted to either side, no effect of alcohol was detected, nor in the movement coordination test. It is concluded that dynamic posturography can detect the effect of alcohol on static and dynamic equilibrium. Test conditions with absent vision appear to be the most sensitive. The results in static conditions are well in agreement with previous studies; the findings under dynamic conditions are new.

Abstinent chronic alcoholics investigated by dynamic posturography, ocular smooth pursuit and visual suppression

Eleven male chronic alcoholic volunteers aged 44-65 years (mean 57 years) were investigated by dynamic posturography, ocular smooth pursuit and visual suppression of the vestibulo-ocular reflex (VOR). Their drinking time ranged from 8-30 years (mean 20 years) and they had been abstinent for the last 1-20 years (mean 7 years). Ocular smooth pursuit showed abnormalities in 8/11. Abnormalities were found in 5/11 in the visual suppression of the VOR. The results of dynamic posturography tests were compared to an age-matched reference material. Dynamic posturography (EquiTest) comprises a sensory organization (SO) part in which the support surface and visual surround are either stable or referenced to the patient's sway, with eyes open or closed. In the SO part the chronic alcoholics had lower equilibrium scores in all test conditions, and the differences were significant in 4 tests out of 6. In a movement coordination part the platform makes active movements, the latencies to which were significantly prolonged in the 2 larger of the 3 translational amplitudes. Adaptation to repeated tilting of the platform was estimated to be pathological in 4/10, compared to none of the controls. The abnormal pattern found in dynamic posturography correlates well with the pathology in ocular smooth pursuit and visual suppression tests, suggested to be due to alcohol induced cerebellar lesions. It is concluded that dynamic posturography is a valuable test for assessing dysequilibrium in chronic alcoholics, even abstinent.