Systematic evaluation of rating scales for drug-induced parkinsonism and recommendations for future research

Slovenian Version of the Drug-Induced Extrapyramidal Symptoms Scale: Evaluation of Interrater and Test-Retest Reliability

AIM

The Drug-Induced Extrapyramidal Symptom Scale (DIEPSS) is a multidimensional rating scale for the assessment of drug-induced extrapyramidal symptoms (EPS), developed in 1994. It is suitable for evaluating EPS considering the degree of influence EPS has on daily activities and the subjective distress that it causes.

METHOD

This study to evaluate the interrater and test-retest reliability of the DIEPSS Slovenian version conducted at the University Medical Center Maribor in Slovenia in November 2018.

RESULTS

Six raters performed the interrater assessment of 135 DIEPSS video clips with recordings of patients with EPS. A second assessment was then performed by 2 raters to evaluate the test-retest reliability, which was high (interclass correlation coefficients from 0.743 to 0.936).

CONCLUSIONS

The results for the Slovenian language version of the DIEPSS show high interrater and test-retest reliability, with high concordance rates for all evaluated items (interclass correlation coefficient > 0.8).

Ginkgo biloba Efficacy in the Treatment of Drug-Induced Parkinsonism: A Randomized Clinical Trial

Background

Drug-induced parkinsonism (DIP) is one of the most common movement disorders in approximately 20 - 35% of patients on antipsychotic medications. Managing the symptoms of DIP is challenging due to the limited number of potentially effective medications. On the other hand, this restricted possible treatment could have numerous side effects that ultimately result in patients stopping the medication all at once. The neuroprotective property of Ginkgo biloba extract (EGb) emerged as an effective commodity for the additional treatment of psychiatric disorders.

Objectives

This study aimed to evaluate the efficacy of EGb in psychiatric patients with symptoms of DIP.

Methods

A sample of 63 patients who met the inclusion criteria were recruited and randomly assigned to control and experimental groups. Both groups were followed for 3 months. One group received 80 mg of G. biloba three times a day, and the control group received a placebo. The patients were evaluated using the Unified Parkinson's Disease Rating Scale and Montreal Cognitive Assessment.

Results

Ginkgo could change the intensity of rest tremors, the severity of motor symptoms, rigidity, and bradykinesia. Ginkgo biloba might alleviate the severity of parkinsonism and motor symptoms and could lead to changes in the two components of working memory and short-term memory.

Conclusions

Ginkgo biloba extract can be used as an effective and safe treatment in the management of DIP, whether in patients diagnosed with psychotic disorders or mood disorders.

SLC6A3, HTR2C and HTR6 Gene Polymorphisms and the Risk of Haloperidol-Induced Parkinsonism

Antipsychotic-induced parkinsonism (AIP) is the most common type of extrapyramidal side effect (EPS), caused by the blockage of dopamine receptors. Since dopamine availability might influence the AIP risk, the dopamine transporter (DAT) and serotonin receptors (5-HTRs), which modulate the dopamine release, may be also involved in the AIP development. As some of the individual differences in the susceptibility to AIP might be due to the genetic background, this study aimed to examine the associations of SLC6A3, HTR2C and HTR6 gene polymorphisms with AIP in haloperidol-treated schizophrenia patients. The Extrapyramidal Symptom Rating Scale (ESRS) was used to evaluate AIP as a separate entity. Genotyping was performed using a PCR, following the extraction of blood DNA. The results revealed significant associations between HTR6 rs1805054 polymorphism and haloperidol-induced tremor and rigidity. Additionally, the findings indicated a combined effect of HTR6 T and SLC6A3 9R alleles on AIP, with their combination associated with significantly lower scores of ESRS subscale II for parkinsonism, ESRS-based tremor or hyperkinesia and ESRS subscales VI and VIII. These genetic predictors of AIP could be helpful in better understanding its pathophysiology, recognizing the individuals at risk of developing AIP and offering personalized therapeutic strategies for the patients suffering from this EPS.

Antipsychotics withdrawal in adults with intellectual disability and challenging behaviour: study protocol for a multicentre double-blind placebo-controlled randomised trial

BACKGROUND

In people with intellectual disability (ID) and challenging behaviour, antipsychotics (AP) are often used off-label and for a long period. Despite a lack of evidence for efficacy for challenging behaviour and concerns about common and clinically relevant side effects, complete withdrawal often fails. We postulate three possible hypotheses for withdrawal failure: 1. Influence of subjective interpretation of behavioural symptoms by caregivers and family; 2. Beneficial effects from AP treatment on undiagnosed psychiatric illness, through improvement in sleep or a direct effect on behaviour; and 3. Misinterpretation of withdrawal symptoms as a recurrence of challenging behaviour.

METHODS

To investigate our hypotheses, we have designed a multicentre double-blind, placebo-controlled randomised trial in which AP (pipamperone or risperidone) are withdrawn. In the withdrawal group, the AP dose is reduced by 25% every 4 weeks and in the control group the dose remains unaltered. Behaviour, sleep, psychiatric disorders, withdrawal symptoms and side effects will be measured and compared between the two groups. If drop-out from the protocol is similar in both groups (non-inferiority), the first hypothesis will be supported. If drop-out is higher in the withdrawal group and an increase is seen in psychiatric disorders, sleep problems and/or behavioural problems compared to the control group, this suggests effectiveness of AP, and indications for AP use should be reconsidered. If drop-out is higher in the withdrawal group and withdrawal symptoms and side effects are more common in the withdrawal group compared to the control group, this supports the hypothesis that withdrawal symptoms contribute to withdrawal failure.

DISCUSSION

In order to develop AP withdrawal guidelines for people with ID, we need to understand why withdrawal of AP is not successful in the majority of people with ID and challenging behaviour. With this study, we will bridge the gap between the lack of available evidence on AP use and withdrawal on the one hand and the international policy drive to reduce prescription of AP in people with ID and challenging behaviour on the other hand.

TRIAL REGISTRATION

This trial is registered in the Netherlands Trial Register (NTR 7232) on October 6, 2018 ( www.trialregister.nl ).

The association of cognitive performance and IL-6 levels in schizophrenia is influenced by age and antipsychotic treatment

Aims: Recent findings suggest that cognitive impairment can be associated with inflammation and immune changes in schizophrenia. We aimed to study possible associations between cytokine levels and cognitive performance in a sample of patients with schizophrenia.Methods: Cognition was assessed with the brief assessment of cognition in schizophrenia in 63 clinically stable outpatients with schizophrenia. Blood was collected and cytokines (IL-2, IL-4, IL-6, IL-10, IL-17A, TNF-α, IFN-γ) were measured by cytometric bead array method. Psychopathological scales were also applied.Results: IL-6 correlated negatively with general cognitive performance (rho = -0.395, p = .017) and positively with antipsychotic dose (rho = 0.412, p = .004). Multiple regression analysis showed that cognitive performance is associated with age and antipsychotic dose (p = .000 and p = .033).Conclusion: The association between IL-6 levels and cognitive performance is dependent on age and antipsychotic dose.

Drug-Induced Extrapyramidal Symptoms Scale of the Norwegian version: inter-rater and test-retest reliability

Background: The Drug-Induced Extrapyramidal Symptoms Scale (DIEPSS) is a multidimensional rating scale designed for the fast, easy and reliable assessment of extrapyramidal symptoms (EPSs) induced by antipsychotics. Aim: The aim of this study was to validate the level of inter-rater and test-retest reliability of the Norwegian translation of this scale. Methods: A total of 125 video clips showing a variety of or no signs of EPSs were used in the present study. The participants recorded were Japanese psychiatric patients receiving first- and/or second-generation antipsychotics. A total of 103 patients (47 males and 56 females), diagnosed with schizophrenia (n = 68) or mood disorders (n = 35) appeared in the video clips. Their mean age was 48.7 ± 16.3 years (range 18-80) at the time of video recording. Inter-rater agreement was assessed with five raters and test-retest reliability with three. Results: Inter-rater reliability analyses showed interclass correlation coefficients (ICCs) ranging from 0.74 to 0.93 for each individual item. Test-retest reliability analysed independently for each rater ranged from 0.71 to 0.96. Conclusions: Inter-rater and test-retest agreement exhibited satisfactory ICC levels above 0.70. The Norwegian version of the DIEPSS is a reliable instrument for the assessment of drug-induced EPSs.

Antipsychotics for patients with pain

Going back to basics prior to mentioning the use of antipsychotics in patients with pain, the International Association for the Study of Pain (IASP) definition of pain can be summarized as an unpleasant experience, composed of sensory experience caused by actual tissue damage and/or emotional experience caused by potential tissue damage. Less used than antidepressants, antipsychotics have also been used for treating this unpleasant experience as adjuvant analgesics without sufficient evidence from research. Because recently developed atypical antipsychotics reduce the adverse reactions of extrapyramidal symptoms, such as acute dystonia, pseudo-parkinsonism, akathisia, and tardive dyskinesia caused by typical antipsychotics, they are expected to be used more frequently in various painful conditions, while increasing the risk of metabolic syndromes (weight gain, diabetes, and dyslipidemia). Various antipsychotics have different neurotransmitter receptor affinities for dopamine (D), 5-hydroxytryptamine (5-HT), adrenergic (α), histamine (H), and muscarinic (M) receptors. Atypical antipsychotics antagonize transient, weak D₂ receptor bindings with strong binding to the 5-HT_2A receptor, while typical antipsychotics block long-lasting, tight D₂ receptor binding. On the contrary, antidepressants in the field of pain management also block the reuptake of similar receptors, mainly on the 5-HT and, next, on the norepinephrine, but rarely on the D receptors. Antipsychotics have been used for treating positive symptoms, such as delusion, hallucination, disorganized thought and behavior, perception disturbance, and inappropriate emotion, rather than the negative, cognitive, and affective symptoms of psychosis. Therefore, an antipsychotic may be prescribed in pain patients with positive symptoms of psychosis during or after controlling all sensory components.

Latent toxoplasma infection in real-world schizophrenia: Results from the national FACE-SZ cohort

OBJECTIVE

Latent Toxoplasma infection has been associated with widespread brain immune activation, increased blood brain barrier permeability, neural disruption, increased dopamine release in dopaminergic neurons, with NMDA activation and with schizophrenia (SZ) onset risk. Toxoplasma has been suggested to be a source of chronic low-grade inflammation and this inflammation has been associated with cognitive impairment in SZ. The objective of the present study were (i) to determine if latent Toxoplasma infection was associated with specific clinical features in stabilized SZ subjects, with cognitive impairment and with increased low-grade peripheral inflammation and (ii) to determine if Treatments with Anti-Toxoplasmic Activity (TATA) were associated with improved outcomes in subjects with latent Toxoplasma infection.

METHODS

A comprehensive 2 daylong clinical and neuropsychological battery was administered in 250 SZ subjects included between 2015 and 2017 in the national FondaMental Expert Center (FACE-SZ) Cohort. Solid phase-enzyme microplate immunoassay methods were used to measure IgG class of antibodies to T. gondii in blood sample. Latent Toxoplasma infection was defined by T. gondii IgG ratio ≥0.8, equivalent to ≥10 international units. Chronic peripheral inflammation was defined by highly sensitive C reactive protein blood level ≥ 3 mg/L.

RESULTS

Latent Toxoplasma infection has been found in 184 (73.6%) of this national multicentric sample. In the multivariate analyses, latent Toxoplasma infection has been significantly associated with higher PANSS negative (aOR = 1.1 [1.1-1.1], p = 0.04) and excitement subscores (aOR = 1.3 [1.1-1.6], p = 0.01), with two specific symptoms (i.e., reference delusion (aOR = 3.6 [1.2-10.6] p = 0.01) and alogia (aOR = 16.7 [2.0-134.7], p = 0.008)) and with chronic low-grade peripheral inflammation (27.2% vs. 7.6%, aOR = 3.8 [1.4-10.3], p = 0.004). Extrapyramidal symptoms remained significantly associated with latent Toxoplasma infection. On the opposite, no significant association of latent Toxoplasma infection with age, gender, age at SZ onset, suicide behavior or cognitive deficits has been found in these models (all p > 0.05). TATA were associated with lower depressive symptoms (aOR = 0.8[0.7-0.9], p = 0.01), and with lower rates of chronic peripheral inflammation (20.9% vs. 48.6%, aOR = 3.5 [1.5-7.9], p = 0.003) but not with higher cognitive scores (p > 0.05).

CONCLUSION

The present findings suggest that Toxoplasma is almost 3 times more frequent in SZ population compared to general population in France. The potential cerebral underpinnings of the association of latent Toxoplasma infection and the above-mentioned outcomes have been discussed. Future studies should confirm that TATA may be effective to reduce Toxoplasma-associated depressive symptoms and low-grade peripheral inflammation.

Drug-induced Extrapyramidal Symptoms Scale (DIEPSS) Serbian Language version: Inter-rater and Test-retest Reliability

Drug-induced Extrapyramidal Symptoms Scale (DIEPSS) is developed in the era of second-generation antipsychotics and is suitable for evaluation of the low incidence of extrapyramidal symptoms occurring in the treatment of atypical antipsychotics, as well as the relationship between personal and social functioning. The study was carried out at the Institute of Mental Health in Serbia in 2015 Study used the 127 DIEPSS video clips material, recorded from 1987 till 2015. Four raters performed the assessment simultaneously, individually rating one assigned item immediately after seeing the video clip. For the purpose of evaluating test-retest reliability the second assessment of the same material was performed nine months after the first assessment. Inter-rater reliability was high for each individual item, with ICCs ranging from 0.769 to 0.949. The inter-rater reliability was highest for akathisia item and lowest for dyskinesia. The test-retest reliability was high for each individual item, with ICC ranging from 0.713 to 0.935. The test-retest reliability was highest for bradykinesia item and lowest for dystonia. The Serbian version of DIEPSS has high level of inter-rater and test-retest reliability. High values of concordance rates (ICC > 0.7) for each evaluated individual item suggest that items of DIEPSS are well defined.

High Incidence and Prevalence of Drug-Related Movement Disorders in Young Patients With Psychotic Disorders

BACKGROUND

Drug-related movement disorders (DRMDs) reduce quality of life and contribute to medication noncompliance of patients with psychotic disorders. Little is known about the epidemiology of DRMDs in relatively young patients a few years after onset of psychosis. This is an important period to study, as the impact of the antipsychotic treatment on the long-term potentiation of the neural pathways associated with psychotic disorders and DRMDs is still minimal. This study investigated the prevalence, incidence, persistence, and clinical correlates of DRMDs in patients during their first years after disease onset.

METHODS

The Genetic Risk and Outcome of Psychosis study is a longitudinal study of 1120 relatively young patients with nonaffective psychosis and a mean age and illness duration of 27 and 4 years, respectively. The following drug-related movement disorders were assessed at baseline and at the 3-year follow-up: parkinsonism, akathisia, tardive dyskinesia, and tardive dystonia. We determined prevalence, incidence, and persistence and investigated clinical correlates at and over the baseline and follow-up assessment.

RESULTS

Patients' mean age and illness duration at baseline were 27.1 and 4.3 years, respectively. In 4 patients, 1 developed a DRMD over the 3-year study period. Prevalence, incidence, and persistence rates were highest for parkinsonism (32%, 21%, and 53%) followed by akathisia (9%, 5%, and 17%) and tardive dyskinesia (4%, 3%, and 20%). Significant associations were found between DRMDs and the patients' age, IQ, and psychopathology.

CONCLUSIONS

The prevalence, persistence, and incidence of DRMDs in this sample were high despite the relatively young age, recent onset of the disorder, and treatment primarily with second-generation antipsychotics. These findings emphasize that screening, diagnosis, and treatment of DRMDs are still important.

The longitudinal trends in the relationship between drug-induced extrapyramidal symptoms and personal and social performance in a population of the patients with schizophrenia: A latent growth model

The aim of this study was to explore the longitudinal trends in the relationship between personal and social functioning and drug-induced extrapyramidal symptoms (DIEPS). The baseline sample included 484 patients with schizophrenia. Participants were assessed at baseline, weeks 4 (time 2), 8 (time 3), and 12 (time 4) regarding social functioning, and DIEPS. In latent growth analysis, the path coefficient between the intercept for the DIEPSS and the intercept for the PSP indicated a significant cross-sectional relationship between these two variables. And the path coefficient between the intercept of the DIEPSS and the slope of the PSP was also significant, indicating that patients who initially had more serious side effects tended to exhibit less improvement in their personal and social functioning over time. Similarly, a significant path coefficient between the slopes of the two variables indicated a dynamic and possibly reciprocal association over time. In addition, K-PSP scale showed good construct validity and reliability. Based on the standardized PSP scale, our results demonstrate DIEPSS induced by antipsychotic treatment dynamically affect personal and social functioning over time, a negative association between psychosocial aspects and the DIEPS.

Early treatment response predicted subsequent clinical response in patients with schizophrenia taking paliperidone extended-release

This 6-week open-labeled study investigated whether early treatment response in patients receiving paliperidone extended-release (paliperidone ER) can facilitate prediction of responses at Week 6. Patients with schizophrenia or schizoaffective disorder were administered 9mg/day of paliperidone ER during the first 2 weeks, after which the dose was adjusted clinically. They were assessed on Days 0, 4, 7, 14, 28, and 42 by the Positive and Negative Syndrome Scale (PANSS). The serum concentrations of 9-hydroxyrisperidone were examined on Days 14 and 42. Among the 41 patients enrolled, 26 were classified as responders (≧50% improvement on total PANSS scores at Week 6). In the receiver-operator curves (ROC) analyses, the changes in total PANSS scores at Week 2 appeared to show more accurate predictability compared to Day 4 and Day 7. At Week 6, no significant correlation was observed between blood 9-hydroxyrisperidone concentration and the total score or changes of PANSS scores. The results suggest that early treatment response to paliperidone ER, particularly at Week 2, can serve as a suitable outcome predictor at Week 6. Using 9mg/day paliperidone ER as an initial dose for schizophrenia treatment exhibited relatively favorable tolerability and feasibility.

Rating scales to measure side effects of antipsychotic medication: A systematic review

INTRODUCTION

Many patients experience side effects during treatment with antipsychotics. This article reviews the clinical use and psychometric characteristics of rating scales used to assess side effects in patients treated with antipsychotics.

METHODS

A systematic literature search was performed using the electronic databases PubMed and Embase, with predefined search terms.

RESULTS

In total, 52 different scales were used in the 440 articles retrieved. For multiple side effects measured with one scale, the Udvalg for Kliniske Undersøgelser Side Effects Rating Scale for Clinicians was used the most, whereas the Liverpool University Neuroleptic Side Effect Rating Scale had the best psychometric characteristics (Cronbach's α 0.81 and test-retest reliability 0.89). The Simpson Angus Scale was used the most to rate extrapyramidal side effects, although the Maryland Psychiatric Research Center scale had the best characteristics (Cronbach's α 0.80, test-retest reliability 0.92 and inter-rater reliability 0.81-0.90). The Arizona Sexual Experience Scale was used the most to assess sexual dysfunction, but the Antipsychotics and Sexual Functioning Questionnaire and the Nagoya Sexual Functioning Questionnaire had the best characteristics.

CONCLUSION

This review will help researchers and clinicians make a purpose-oriented choice of which scale to use.

SYSTEMATIC REVIEW REGISTRATION NUMBER

CRD42014013010.

Antipsychotic-induced parkinsonism is associated with working memory deficits in schizophrenia-spectrum disorders

In view of the significant cognitive deficits in schizophrenia and their impact on patients' social and occupational functioning, and considering that the influence potential influence of antipsychotic-induced extrapyramidal symptoms on cognition in schizophrenia remains poorly understood, the current study sought to identify the clinical, socio-demographic and neurologic predictors of the cognitive performance of schizophrenia patients. Eighty-two schizophrenia-spectrum (DSM-IV criteria) outpatients were recruited. Psychiatric symptoms were evaluated with the Positive And Negative Syndrome Scale and the Calgary Depression Scale for Schizophrenia. Extrapyramidal symptoms were evaluated with the Extrapyramidal Symptoms Rating Scale, while spatial working, planning abilities and visual paired associates learning were evaluated with the CAmbridge Neuropsychological Tests Automated Battery. The Stroop test was also administered. Multivariate hierarchic linear regression analyses were performed. We found that negative symptoms were associated with cognitive flexibility, planning, visual learning and working memory performance in schizophrenia. Age, sex, number of hospitalizations and antipsychotic type also emerged as significant predictors. More importantly, we found a significant association between antipsychotic-induced parkinsonism and working memory performance. The fact that negative symptoms and socio-demographic variables predicted cognitive performance in schizophrenia is consistent with the previous literature on the topic. The finding of an association between parkinsonism and working memory may have clinical implications, since working memory deficits are considered putative endophenotypes of schizophrenia and are known to impair patients' social and occupational functioning. Our results will need to be replicated in longitudinal studies involving larger samples of patients.

Genetic variation and the risk of haloperidol-related parkinsonism in elderly patients: a candidate gene approach

Factors that influence the variation in occurrence of antipsychotic-related parkinsonism in elderly have not been well elucidated. The aim of this study was to investigate whether previous identified and studied genetic polymorphisms at DRD2, ANKK1, DRD3, HTR2A, HTR2C, RGS2, COMT, and BDNF genes are associated with antipsychotic-related parkinsonism in elderly patients.This cross-sectional study included 150 inpatients aged 65 years and older who were treated with haloperidol. Parkinsonism assessed by the Simpson Angus Scale was present in 46% of the included patients. The investigated predictors were polymorphisms in DRD2 (141CIns/Del and C957T), ANNK1 (TaqIA), DRD3 (Ser9Gly), HTR2A (-1438G>A and His452Tyr), HTR2C (Cys23Ser and -759C/T), RGS2 (+2971C>G), COMT (G158A), and BDNF (Val66Met). Frequencies of the -759 T allele of the HTR2C gene and the 158A allele of the COMT gene were significantly higher in patients without antipsychotic-induced parkinsonism (AIP) (nominal P = 0.03 and P = 0.02, respectively). -759 T allele carriership in females was associated with a lower risk of AIP (adjusted odds ratio, 0.31; 95% confidence interval, 0.11-0.85). The decrease in risk of AIP in carriers of the COMT 158A allele did not reach statistical significance. No significant associations were found between AIP and the remaining selected polymorphisms.Although validation is needed, this study suggests that carriership of the -759 T allele of the HTR2C gene in females may be protective against development of parkinsonism in elderly patients during treatment with haloperidol.

Parkinsonism in elderly users of haloperidol: associated with dose, plasma concentration, and duration of use

Factors that influence the variation in occurrence of antipsychotic-induced parkinsonism (AIP) in the elderly have not been well elucidated. The aim of this study was to investigate the association between parkinsonism in elderly users of haloperidol and prescribed dose, plasma concentration, and duration of use of haloperidol in a cross-sectional design. This study included 150 inpatients aged 65 years and older who were treated with haloperidol. Parkinsonism assessed by the Simpson Angus Scale was present in 46% of the included patients. Prescribed haloperidol dose varied from 0.3 to 5 mg/d. Plasma concentration ranged from 0.13 to 4.11 μg/L, with one outlying measurement (21.43 μg/L). Dose is moderate but significantly associated with haloperidol plasma concentration (weighted R2 = 0.32; P < 0.001). Variability in the total score on the Simpson Angus Scale could not be explained by the variability in dose, concentration (respectively R2 = 0.003 and 0.001) nor duration of use of haloperidol. Smoking showed to be not significantly protective in the development of AIP (crude odds ratio, 0.39; 95% confidence interval, 0.15-0.997; and adjusted odds ratio, 0.44; 95% confidence interval, 0.17-1.17). In a clinical practice-setting dose, neither plasma concentration nor duration of use of haloperidol is associated with an increased occurrence of AIP. This study does not support the hypothesis of the peripheral pharmacokinetic explanation for the high prevalence of AIP and differences in AIP sensitivity in the elderly during treatment with haloperidol.

Monitoring and documentation of side effects from depot antipsychotic medication: an interdisciplinary audit of practice in a regional mental health service

This audit reviewed current practice within a rural mental health service area on the monitoring and documentation of side effects of antipsychotic depot medication. A sample of 60 case files, care plans and prescriptions were audited, which is 31% of the total number of service users receiving depot injections in the mental health service region (n= 181). The sample audited had a range of diagnoses, including: schizophrenia, schizoaffective disorder, bipolar affective disorder, depression, alcoholic hallucinosis and autism. The audit results revealed that most service users had an annual documented medical review and a documented prescription. However, only five (8%) case notes examined had documentation recorded describing the condition of the injection site, and alternation of the injection site was recorded in only 28 (47%) case notes. No case notes examined had written consent to commence treatment recorded. In 57 (95%) of case notes, no documentation of recorded information on the depot and on side effects was given. The failure to monitor and record some blood tests was partly attributed to a lack of clarity regarding whose responsibility it was. A standardized checklist has been developed as a result of the audit and this will be introduced by all teams across the service.

Ocular motor abnormalities in Parkinsonian syndromes

Oculomotor abnormalities can be observed in all Parkinsonian syndromes (PS). Nevertheless, due to the considerable overlap of oculomotor pathology in Parkinsonism, oculomotor changes are not generally considered to contribute substantially to the differential diagnosis of PS. Here we review the characteristics of oculomotor disturbances in the major PS, we provide a survey of the current concepts of the underlying neural physiology of oculomotor control and a summary of the major recording techniques for eye movements. The main focus of this review is to outline the subtle differences between apparently similar oculomotor alterations in Parkinson's disease (PD) and atypical neurodegenerative PS that can contribute to the early differential diagnosis of these entities.