Relationship between primitive reflexes and severity in Parkinson's disease

The grasp reflex in patients with idiopathic normal pressure hydrocephalus

OBJECTIVE

To investigate the prevalence and intensity of grasp reflexes and to examine changes in these reflexes after shunt surgery in patients with idiopathic normal pressure hydrocephalus (iNPH).

METHODS

We enrolled 147 patients with probable iNPH. A standard procedure was used to determine the presence of grasp reflexes, and the intensity of these reflexes was assessed using a four-category classification. Clinical rating scales and their correlation with grasp reflexes were also evaluated. Grasp reflexes were reassessed in 72 patients 1 year after surgery.

RESULTS

We found that approximately 50.3% of patients with iNPH exhibited a positive grasp reflex. Among these patients, 69% exhibited bilateral positivity, while the remaining patients showed unilateral positivity. Furthermore, the intensity of the grasp reflex was significantly correlated with the severity of gait and with cognitive, urinary, motor, and behavioural symptoms. Surgical interventions led to a reduction (41.7%) or maintenance (30.6%) of the reflex intensity in 72.3% of iNPH patients. The changes in reflex intensity showed significant positive correlations with changes in the number of steps of the Timed Up and Go test and Trail Making Test-A scores but not with changes in total scores on the iNPH Grading Scale.

CONCLUSION

This retrospective study identified grasp reflexes as a highly prevalent phenomenon in patients with iNPH. These reflexes can assist in evaluating the severity of various symptoms, including cognitive, gait, urinary, motor and emotional symptoms.

Modeling Parkinson's disease-related symptoms in alpha-synuclein overexpressing mice

BACKGROUND

Intracellular deposition of alpha-synuclein (α-syn) as Lewy bodies and Lewy neurites is a central event in the pathogenesis of Parkinson's disease (PD) and other α-synucleinopathies. Transgenic mouse models overexpressing human α-syn, are useful research tools in preclinical studies of pathogenetic mechanisms. Such mice develop α-syn inclusions as well as neurodegeneration with a topographical distribution that varies depending on the choice of promoter and which form of α-syn that is overexpressed. Moreover, they display motor symptoms and cognitive disturbances that to some extent resemble the human conditions.

PURPOSE

One of the main motives for assessing behavior in these mouse models is to evaluate the potential of new treatment strategies, including their impact on motor and cognitive symptoms. However, due to a high within-group variability with respect to such features, the behavioral studies need to be applied with caution. In this review, we discuss how to make appropriate choices in the experimental design and which tests that are most suitable for the evaluation of PD-related symptoms in such studies.

METHODS

We have evaluated published results on two selected transgenic mouse models overexpressing wild type (L61) and mutated (A30P) α-syn in the context of their validity and utility for different types of behavioral studies.

CONCLUSIONS

By applying appropriate behavioral tests, α-syn transgenic mouse models provide an appropriate experimental platform for studies of symptoms related to PD and other α-synucleinopathies.

High-level language production in Parkinson's disease: a review

This paper discusses impairments of high-level, complex language production in Parkinson's disease (PD), defined as sentence and discourse production, and situates these impairments within the framework of current psycholinguistic theories of language production. The paper comprises three major sections, an overview of the effects of PD on the brain and cognition, a review of the literature on language production in PD, and a discussion of the stages of the language production process that are impaired in PD. Overall, the literature converges on a few common characteristics of language production in PD: reduced information content, impaired grammaticality, disrupted fluency, and reduced syntactic complexity. Many studies also document the strong impact of differences in cognitive ability on language production. Based on the data, PD affects all stages of language production including conceptualization and functional and positional processing. Furthermore, impairments at all stages appear to be exacerbated by impairments in cognitive abilities.

The grasp reflex: a symptom in need of treatment

The grasp reflex is one of the primitive reflexes frequently observed in neurodegenerative diseases. However, quality of life and treatment of the grasp reflex are neglected in the literature. Following two brief case vignettes of patients seen recently who experienced disability from a grasp reflex, we briefly review its phenomenology, anatomy-physiology and epidemiology in neurodegenerative movement disorders, and assess the limited current literature regarding the quality of life and treatment.

Cortical release signs in psychiatry

OBJECTIVE

To review the role of cortical release signs (CRS) in neuropsychiatry.

METHOD

A thorough literature review was conducted using Medline and Psychlit databases, and other relevant references available to the authors.

RESULTS

A number of neurological abnormalities are reported at elevated rates in neuropsychiatric conditions. CRS are a group of primitive reflexes that are present in the neonate but become inhibited as the infant central nervous system (CNS) develops, only to later re-emerge in the context of CNS disease. The clinical elicitation and interpretation of each CRS is described with reference to its neurobiology. The prevalence of CRS in schizophrenia, affective disorder, obsessive-compulsive disorder, Alzheimer's disease, vascular dementia, frontotemporal dementia and other neuropsychiatric illness allows for their use in the clinical management of these patients, including diagnostic assessment, treatment monitoring and prognosis.

CONCLUSIONS

A number of issues complicate their interpretation in neuropsychiatric illness, including the apparent high base rate of some CRS in non-clinical populations, their increasing prevalence with age, lack of specificity and uncertainty over what constitutes an 'abnormal' response. In some circumstances, CRS may assist in diagnostic differentiation and illness staging.

Glabellar and palmomental reflexes in parkinsonian disorders

The authors examined the glabellar reflex and the palmomental reflex in 100 subjects, including patients with Parkinson disease (n = 41), patients with progressive supranuclear palsy (n = 12), patients with multiple system atrophy (n = 7), and healthy, age-matched, controls (n = 40). The study provides evidence that these reflexes, particularly glabellar reflex, are relatively sensitive signs of parkinsonian disorders, but they lack specificity as they do not differentiate among the three most common parkinsonian disorders.

Electrophysiological assessments of primitive reflexes in stroke patients

OBJECTIVE

To evaluate the primitive reflexes by electrophysiological assessments and their correlation with the cognitive and physical functioning of stroke patients.

METHODS

Electrophysiological studies of primitive reflexes including jaw jerk, snout reflex, glabellar reflex, and corneomandibular reflexes were performed in 38 stroke patients and 26 normal controls. Cognitive function of patients was assessed by Modified Mini-Mental State (3MS) Examination and logical memory test. The Chinese Functional Independence Scale (CFIS) was used to evaluate the physical functioning and social domains of stroke patients.

RESULTS

The presence rate of primitive reflexes was higher in stroke patients than in normal controls. Wave amplitude of snout and corneomandibular reflexes obtained from stroke patients was greater than those from controls. No definite difference in reflex conduction latencies was observed between the two groups. A regression relationship was noted between the wave amplitude of snout reflexes and the 3MS and CFIS scores of stroke patients.

CONCLUSION

Primitive reflexes can be measured by electrophysiological assessments. The results may serve as an objective and useful parameter in evaluation of cognition and physical functioning of stroke patients.

Positive and negative factors in movement control: a current review of Denny-Brown's hypothesis

In his extensive writings, Denny-Brown hypothesized that two competitive 'tropisms,' one positive (exploratory) and one negative (withdrawal) act to coordinate normal movements at all levels of the neuraxis. Lesions in particular areas of the central nervous system result in disequilibrium between these tropisms, leading to disorders of posture and movement, including involuntary movements. The tactile manifestations of unbalanced exploratory tropisms are grasping responses, whereas the complementary withdrawal tropisms are avoiding responses. In Denny-Brown's view, at the level of the cerebral cortex, grasping responses result from frontal lobe injury whereas avoiding responses result from parietal lobe lesions. In this report we review Denny-Brown's conceptions of positive and negative tropisms, their anatomical loci, and whether his hypothesis has merit in a contemporary approach to brain function. We find that Denny-Brown's view on the anatomical loci associated with these behaviors is incomplete, but that the idea of conflicting behavioral tendencies is valuable for understanding and managing some neurological and perhaps also psychiatric disorders. For example, his hypothesis offers an important perspective in understanding the paradoxical success of stereotaxic surgery to alleviate the symptoms of Parkinson's disease.

Classical eyeblink conditioning in Parkinson's disease

Patients with Parkinson's disease (PD) show impairments of a range of motor learning tasks, including tracking or serial reaction time task learning. Our study investigated whether such deficits would also be seen on a simple type of motor learning, classic conditioning of the eyeblink response. Medicated and unmediated patients with PD showed intact unconditioned eyeblink responses and significant learning across acquisition; the learning rates did not differ from those of healthy control subjects. The overall frequency of conditioned responses was significantly higher in the medicated patients with PD relative to control subjects, and there was also some evidence of facilitation in the unmedicated patients with PD. Conditioning of electrodermal and electrocortical responses was comparable in all groups. The findings are discussed in terms of enhanced excitability of brainstem pathways in PD and of the involvement of different neuronal circuits in different types of motor learning.

Primitive reflexes in Alzheimer's disease and vascular dementia

Data on the prevalence and clinical value of primitive reflexes (PRs) in dementia are controversial, mainly due to a lack of standardization of the methods by which these signs are elicited and scored. A standardized protocol was used to investigate eight PRs in 20 patients with Alzheimer's disease (AD), 20 patients with vascular dementia (VD), and 20 control subjects for each group. Both patient groups showed considerably more PRs than the control groups. The prevalence of PRs was related to the severity of dementia. No single reflex or combination of PR pathognomonic for dementia could be distinguished. The PR profile of AD and VD patients were similar.

Primitive reflexes in Parkinson's disease

A standardised protocol for the examination of 15 primitive reflexes in which the amplitude and the persistence were scored separately, was applied to 25 patients with Parkinson's disease and an equal number of healthy matched control subjects. Most reflexes were found considerably more often in the patients than in the control subjects, especially the snout, the glabellar tap, and its variant, the nasopalpebral reflex. Only the mouth open finger spread reflex was present more often in the control subjects. For all reflexes except this last, the scores for amplitude and persistence of the reflexes for the control group never exceeded the scores for the patient group. Reflexes persisted more often in the patients than in the control subjects. Parkinsonism alone can explain a large number of primitive reflexes, irrespective of the severity or duration of the disease. In contrast, the number of reflexes was related more closely to cognitive scales. It is concluded that such reflexes may be helpful in diagnosing Parkinson's disease. In addition, a standardised protocol for eliciting and scoring is essential for the study of these reflexes in parkinsonism and other neuropsychiatric conditions.

Primitive reflexes in healthy, adult volunteers and neurological patients: methodological issues

A study was made to determine whether two experienced clinicians elicited and scored primitive reflexes (PR) differently and whether reliability could be improved by standardization. Three studies were carried out, using a protocol for the examination of 14 PR. In the first study with 31 healthy young subjects, two investigators found virtually no difference in the routine neurological examination. However, the interobserver agreement was very poor, indicating the need for a further improvement of the PR protocol. In the second study, 30 neurological patients were examined with an improved, more explicit and standardized protocol, in which the amplitude and the persistence of the reflex were scored separately. Interobserver agreement improved considerably, and was high for amplitude as well as persistence. In the third study, 36 neurological patients were examined twice by one investigator within 2 weeks. Good to excellent intraobserver agreement was found. No pathognomonic or strictly localizing reflex could be distinguished.

Blinking in patients with memory disorders during short term memory tasks

The occurrence of blinking during short term memory tasks was analyzed for 32 subjects divided into three groups: 12 memory impaired patients, 10 elderly normals (age-matched to the patients), and 10 young normals. The subjects were participating in a study of brain evoked potentials accompanying memory activities. They were instructed not to blink during the performance of the memory tasks for reasons related to the quality of the recorded potentials. In this context, the withholding of blinking can be considered a secondary task. Blinking during the short term memory tasks was inversely related to performance accuracy (r = -.57). Age, mini-mental score and reaction time were also significantly related to the frequency of blinking. Dividing the memory patients into two groups according to the incidence of blinking, ("high-blinking" and "low-blinking"), revealed a significant difference in overall task accuracy with the high-blinking group performing more poorly than the low-blinking group.

Neuroradiological covariates of drug-induced parkinsonism and tardive dyskinesia in schizophrenia

Computed tomographic (CT) studies have demonstrated structural brain abnormalities including cortical atrophy and enlarged lateral ventricles in a subset of schizophrenic patients including those with abnormal involuntary movements. In the following series of studies, we present our findings pertaining to neuroradiological covariates of drug-induced Parkinsonism and Tardive dyskinesia in schizophrenic patients. In these studies we have explored the relationship of Parkinsonism and Tardive dyskinesia to pineal and choroid plexus calcification. In addition, we also investigated the relationship of pineal calcification to schizophrenia, and specifically to the paranoid and nonparanoid subgroups. In a further series of studies, we investigated the neuroradiological covariates of disorders of gait and posture as well as tremor in schizophrenic patients with drug-induced Parkinsonism. In addition, we explored the relationship of Tardive dyskinesia and its subsyndromes to CT scan measurements of cortical and subcortical atrophy in schizophrenia. Our findings highlight the significance of the pineal gland in the pathophysiology of schizophrenia and drug-induced movement disorders. Furthermore, these studies underscore the heterogeneity of Parkinsonism and Tardive dyskinesia.

The relationship of negative schizophrenia to parkinsonism

The positive-negative distinction of schizophrenia has emerged as a valid means of clarifying its heterogeneity. Despite evidence that the two symptom classes may reflect different dimensions of the disease, there is presently no integrated model for understanding of the pathophysiology of these symptoms and their co-occurrence in schizophrenia. We propose that negative phenomena of schizophrenia may be a variant of Parkinsonism. This view is supported by the overlap with Parkinsonism in terms of clinical features, neurochemistry, pharmacology, as well as neuroradiological and neuropathological aspects. As such, negative symptoms may be a manifestation of disease of the basal ganglia and constitute the core pathology in schizophrenia. Positive symptoms, conversely, may reflect an "accessory" process related to a compensatory increase in striatal and limbic dopamine activity following an injury to the dopaminergic system. In the present communication we present a series of studies that support the association of negative schizophrenia and Parkinsonism. Based on this evidence, we suggest that schizophrenic patients with prominent negative symptoms might be managed like patients with Parkinson's disease, namely, with dopaminergic drugs and MAO-B inhibitors. Finally, the association of negative schizophrenia with Parkinsonism raises the possibility that adrenal medullary tissue transplantation, which may benefit a selected group of Parkinsonian patients, may be a future promising therapy for refractory negative schizophrenia.

Relationship between primitive reflexes, extra-pyramidal signs, reflective apraxia and severity of cognitive impairment in dementia of the Alzheimer type

Controversy exists in the literature about the significance of primitive reflexes (PR) and extrapyramidal signs (EP) as diffuse cortical dysfunction signs and their relationship to age and cognitive impairment. A sample of 91 patients with a dementia of the Alzheimer type were examined with a standardized technique to assess the relationship between the finding of PR, EP and severity of cognitive impairment measured by Mini-Mental Status Examination. The value of a short cognitive test, the reflective apraxia (i.e. imitation of meaningless gestures), were also assessed. A significantly lower MMS score was correlated with the number of present PR and with presence of snout, sucking and grasping reflexes. No correlation was found between presence or absence of PR and age, depression, or drug therapy. EP score was correlated with the number of present PR and MMS, but not with age. Reflective apraxia score was significantly correlated with the degree of cognitive impairment and was found with lower cognitive impairment than PR.

Primitive (developmental) reflexes and diffuse cerebral dysfunction in schizophrenia and bipolar affective disorder: overrepresentation in patients with tardive dyskinesia

Primitive (developmental) reflexes are present in fetal and infant life, but disappear in adulthood. Their elicitation in later life usually occurs in association with cortical or diffuse cerebral dysfunction and suggests a new approach to the issue of whether tardive dyskinesia is particularly likely to occur in patients with organic brain disorder(s). Sixty-six patients with schizophrenia (age range 50-86) and 18 with bipolar affective disorder (age range 40-77) were assessed for the presence of involuntary movements and for the release of the grasp, palmomental, snout, corneomandibular, and glabellar reflexes. In each diagnostic group, patients with involuntary movements showed a significant excess of primitive reflexes in comparison with otherwise indistinguishable patients without such movements. These results complement recent reports that similar patients with involuntary movements also show greater cognitive impairment and point anew to an association between the presence of tardive dyskinesia and of organic brain dysfunction. They raise again the issue of whether or not such dysfunction may be a consequence of neurodevelopmental abnormality rather than of neurodegenerative processes.

Intellectual impairment in Parkinson's disease: clinical, pathologic, and biochemical correlates

The prevalence of overt dementia in 27 studies representing 4,336 Parkinson's disease (PD) patients was 39.9%. The studies reporting the highest incidence of intellectual impairment (69.9%) used psychologic assessment techniques, whereas studies identifying the lowest prevalence of dementia (30.2%) depended on nonstandardized clinical examinations. Neuropsychologic investigations reveal that PD patients manifest impairment in memory, visuospatial skills, and set aptitude. Language function is largely spared. Intellectual deterioration in PD correlates with age, akinesia, duration, and treatment status. Neuropathologic and neurochemical observations demonstrate that PD is a heterogeneous disorder: the classic subcortical pathology with dopamine deficiency may be complicated by atrophy of nucleus basalis and superimposed cortical cholinergic deficits, and a few patients have the histopathologic hallmarks of Alzheimer's disease. Mild intellectual loss occurs with the classic pathology, and the more severe dementia syndromes have cholinergic alterations or Alzheimer's disease. Thus, PD includes several syndromes of intellectual impairment with variable pathologic and neurochemical correlates.

Response properties of the perioral reflex in Parkinson's disease

Analyses of the response magnitudes of the short-latency perioral reflex were made in a group of Parkinson disease patients and control subjects. As a group, the parkinsonian subjects manifested reflex magnitudes which were increased relative to normal. For low-acceleration, mechanical displacements of perioral tissue (less than 500 cm/s2), the perioral reflex was not elicited in normal controls. However, such low-acceleration stimuli did elicit the perioral reflex in more than half of the parkinsonian subjects studied. These findings are consistent with earlier findings of increased sensitivity of facial and perioral reflexes associated with disturbances of the basal ganglia. These results contribute to the understanding of specific stimulus-response characteristics of the facial reflex and the role of the basal ganglia in orofacial motor control. The finding of increased sensitivity to mechanical stimuli in Parkinson's disease supports the hypothesis of basal ganglia gating or regulation of afferent information.