Battery Of Neurophysiological Tests Research Articles

Impact of sleep quality on cognitive functions in Parkinson’s disease

BACKGROUND: Sleep disorders lead to cognitive deficits in healthy people and are thought to have significant impact on cognition in Parkinson’s disease (PD). OBJECTIVE: To study the sleep pattern and its relationship to cognitive functioning in non-demented PD cohort. MATERIALS AND METHODS: Sleep was evaluated by Pittsburg Sleep Quality Index (PSQI) in a cohort of PD patients. Comprehensive assessment of cognitive domains including attention, executive functions, short/long-term verbal memory, visual memory, and visuospatial functioning was done by battery of neuro-physiological tests on patients in “ON” state. Based on the component PSQI sleep score, patients were grouped as having good quality sleep (PSQI score ≤ 5) or poor quality sleep (PSQI score > 5). The demographic profile, disease characteristics, treatment, and cognitive tests were then compared between the two groups. RESULTS: Of 130 patients with diagnosis of PD, 85 patients were included. 63 (74.1%) had good sleep quality while 22 (25.9%) had poor sleep quality. Mean age and disease characteristic were comparable between two groups except that females had statistically significant (P = 0.001) poor sleep quality as compared to men. Poor sleep quality had significant effect on cognitive functions including generativity, inhibition, set-shifting, perseveration, and attention but there was no impact of sleep on verbal memory, visual memory, and visuospatial abilities. CONCLUSION: PD patients with poor sleep quality on PSQI questionnaire should be carefully screened for presence of any cognitive impairment especially executive impairment, as these two may be inter-related. Intervention to improve sleep would have far reaching benefits to improve the quality of life of PD patients.

Alteration of cortical but not spinal inhibitory circuits in idiopathic scoliosis

Background: The pathogenesis of adolescent idiopathic scoliosis (AIS), including the role of brain and spinal inhibitory circuits, is still poorly elucidated. The aim of this study was to identify which central inhibitory mechanisms are involved in the pathogenesis of AIS. Design: A prospective neurophysiological study, using a battery of neurophysiological tests, such as cutaneous (CuSP) and cortical (CoSP) silent periods, motor evoked potentials (MEP) and paired-pulse transcranial magnetic stimulation (ppTMS). Settings: Neurophysiological laboratory. Participants: Sixteen patients with AIS (14 females, median age 14.4) and healthy controls. Outcome measures: MEPs were obtained after transcranial magnetic stimulation (TMS) and recorded from the abductor pollicis muscle (APB). ppTMS was obtained at interval ratios (ISI) of 1, 2, 3, 6, 10, 15 and 20 ms. The cortical silent period (CoSP) was recorded from the APB. The cutaneous silent period (CuSP) was measured after painful stimuli delivered to the thumb while the subjects maintained voluntary contraction of the intrinsic hand muscles. The data were analyzed and compared with those from healthy subjects. Results: The CoSP duration was significantly prolonged in AIS patients. A significantly higher amplitude of ppTMS for ISI was found in all AIS patients, without remarkable left-right side differences. No significant difference in MEP latency or amplitude nor in the CuSP duration was obtained. Conclusion: Our observation demonstrates evidence of central nervous system involvement in adolescent idiopathic scoliosis (AIS). Lower intracortical inhibition, higher motor cortex excitability, and preserved spinal inhibitory circuits are the main findings of this study. A possible explanation of these changes could be attributed to impaired sensorimotor integration predominantly at the cortical level.

Prevalence of discomplete sensorimotor spinal cord injury as evidenced by neurophysiological methods: A cross-sectional study.

ObjectivesTo assess the prevalence of residual trans-lesion connectivity in persons with chronic clinically complete spinal cord injury (discompleteness) by neurophysiological methods.ParticipantsA total of 23 adults with chronic sensorimotor complete spinal cord injury, identified through regional registries the regional spinal cord registry of Östergötland, Sweden.MethodsDiagnosis of clinically complete spinal cord injury was verified by standardized neurological examination. Then, a neurophysiological examination was performed, comprising electroneurography, electromyography, sympathetic skin response and evoked potentials (sensory, laser and motor). Based on this assessment, a composite outcome measure, indicating either strong, possible or no evidence of discomplete spinal cord injury, was formed.ResultsStrong neurophysiological evidence of discomplete spinal cord injury was found in 17% (4/23) of participants. If also accepting “possible evidence”, the discomplete group comprised 39% (9/23). The remaining 61% showed no neurophysiological evidence of discompleteness. However, if also counting reports of subjective sensation elicited during neurophysiological testing in the absence of objective findings, 52% (12/23) showed indication of discomplete spinal cord injury.CONCLUSIONEvidence of discomplete spinal cord injury can be demonstrated using standard neurophysiological techniques in a substantial subset of individuals with clinically complete spinal cord injury. This study adds to the evidence base indicating the potential of various modes of cross-lesional sensorimotor functional restoration in some cases of chronic clinically complete spinal cord injury.LAY ABSTRACTSpinal cord injuries are usually classed as complete or incomplete. A complete injury implies that no residual function exists below the neurological level of injury. This status is determined by standardized neurological examination and is thought to correlate with spinal cord function in each individual with spinal cord injuries. However, studies have indicated that, in some people with complete spinal cord injury, there may be residual function that is not detected by such testing. The aim of the current study was to examine whether residual function, which is not detected by such testing, exists, and, if so, how common it is among people with complete spinal cord injuries (based on clinical testing) in a chronic stage (>2 years since injury). A battery of neurophysiological tests was used. Signs of “subclinical” residual function were found in 17–39% of 23 participants. This finding may lead to improvements in rehabilitative outcomes for people with complete spinal cord injury.

More than blindsight: Case report of a child with extraordinary visual capacity following perinatal bilateral occipital lobe injury

Injury to the primary visual cortex (V1, striate cortex) and the geniculostriate pathway in adults results in cortical blindness, abolishing conscious visual perception. Early studies by Larry Weiskrantz and colleagues demonstrated that some patients with an occipital-lobe injury exhibited a degree of unconscious vision and visually-guided behaviour within the blind field. A more recent focus has been the observed phenomenon whereby early-life injury to V1 often results in the preservation of visual perception in both monkeys and humans. These findings initiated a concerted effort on multiple fronts, including nonhuman primate studies, to uncover the neural substrate/s of the spared conscious vision. In both adult and early-life cases of V1 injury, evidence suggests the involvement of the Middle Temporal area (MT) of the extrastriate visual cortex, which is an integral component area of the dorsal stream and is also associated with visually-guided behaviors. Because of the limited number of early-life V1 injury cases for humans, the outstanding question in the field is what secondary visual pathways are responsible for this extraordinary capacity? Here we report for the first time a case of a child (B.I.) who suffered a bilateral occipital-lobe injury in the first two weeks postnatally due to medium-chain acyl-Co-A dehydrogenase deficiency. At 6 years of age, B.I. underwent a battery of neurophysiological tests, as well as structural and diffusion MRI and ophthalmic examination at 7 years. Despite the extensive bilateral occipital cortical damage, B.I. has extensive conscious visual abilities, is not blind, and can use vision to navigate his environment. Furthermore, unlike blindsight patients, he can readily and consciously identify happy and neutral faces and colors, tasks associated with ventral stream processing. These findings suggest significant re-routing of visual information. To identify the putative visual pathway/s responsible for this ability, MRI tractography of secondary visual pathways connecting MT with the lateral geniculate nucleus (LGN) and the inferior pulvinar (PI) were analysed. Results revealed an increased PI-MT pathway in the left hemisphere, suggesting that this pulvinar relay could be the neural pathway affording the preserved visual capacity following an early-life lesion of V1. These findings corroborate anatomical evidence from monkeys showing an enhanced PI-MT pathway following an early-life lesion of V1, compared to adults.

7. Neurophysiology in diagnosis and prognosis of multiple sclerosis in age of magnetic resonance imaging

Objective The advent of magnetic resonance imaging techniques has greatly reduced the diagnostic value of neurophysiological tests in MS, particularly evoked potentials. In disease progression, most of MS patients accumulate inflammatory lesions, axonal damage, and progressive brain atrophy, along with an increasing degree of disability. More promising is the utilization of neurophysiological tests to quantify the severity of white matter involvement. Methods Evoked potentials (EP) have been still used in multiple sclerosis (MS) especially in its early diagnosis. Recently, multimodal EPs appears to be a prognostic factor for disease progression ( Schlaeger et al., 2012 , Invernizzi et al., 2011 , Schlaeger et al., 2012 ). Deeper insights about causal and functional relationships in plasticity of the motor system in patients with MS were gained by neurophysiological techniques, predominantly by transcranial magnetic stimulation. Results Visual evoked potential (VEP) are preferentially used in early diagnosis of MS for detection of subclinical optic neuritis. Somatosensory (SEP) and motor (MEP) evoked potentials reveal subclinical lesions in the CNS and could be a supplementary diagnostic tests for sensory and motor system disturbances. MEP abnormalities correlate with the degree of motor impairment and disability. A number of functional imaging studies have assessed patterns of brain activation during simple motor tasks in MS patients and their relationship with CNS damage and motor function. Conclusion Evoked potentials are functional neurophysiological methods highly sensitive in revealing ,,silent lesions“ especially at the beginning of MS. Multimodal evoked potentials have indisputable benefit of prognostic value to determine non-responders, ,,benign“ course of the disease and identification of patients with significant disease progression. A battery of neurophysiological tests could be useful in monitoring the disease progression in individual patient and as surrogate endpoints in clinical trials. Supported by Research Project of Charles University PRVOUK P34, Czech Republic.

Neurophysiological markers of small fibre neuropathy in TTR-FAP mutation carriers

Individuals carrying the amyloidogenic transthyretin (TTR) mutation are predisposed to develop familial amyloid polyneuropathy (FAP). The first clinical manifestations are often subjective sensory symptoms and, therefore, objective markers are needed to confirm the onset of TTR-FAP. The purpose of this study was to evaluate the usefulness of a comprehensive battery of neurophysiological tests to provide early markers of FAP in TTR-mutation carriers. Twenty patients with documented pathogenic TTR mutation were enrolled, including eight clinically asymptomatic carriers and 12 paucisymptomatic carriers who had subjective sensory symptoms or doubtful sensory signs but no firm clinical deficit at clinical examination. Neurophysiological assessment of large fibres consisted of conventional nerve conduction studies. Small-fibre tests included laser evoked potentials, sympathetic skin responses and the measurement of cold and warm detection thresholds and heart-rate variability. Abnormalities in small-fibre tests were found in two of the eight asymptomatic carriers and nine of the 12 paucisymptomatic carriers. In contrast, conventional conduction studies did not show any sign of polyneuropathy. Early neuropathic involvement in TTR-mutation carriers can be detected or confirmed by neurophysiological tests specifically assessing small nerve fibres. These tests did not show any redundancy or difference in their sensitivity, emphasizing the value of combining them for TTR-FAP diagnosis.

Possible Neurophysiological Markers of Early Neurodegenerative Process: Parkinson’s Disease

We used tests for evaluation of latent period, duration, and accuracy of eyes, head, or hand movements and their coordinated movements. Comparative analysis of these parameters was performed in healthy subjects and in patients with early stages of Parkinson's disease. The pathology data significantly (p<0.05) differed from those in normal control subjects. These results can be used as neurophysiological markers of early neurodegenerative process. Increasing the number of tests would lead to better specificity of the markers. It will be possible to create a battery of neurophysiological tests most likely reflecting the predictive basis of early neurodegenerative process.

Heart rate variability in Parkinson’s disease unaffected by deep brain stimulation

Our aim was to investigate the impact of subthalamic nucleus deep brain stimulation (STN-DBS) on the cardiovagal control of patients with advanced Parkinson's disease. Twenty-four patients (mean age: 62.1 ± 9.4 years) were examined 3 days before and 6 months after DBS by a questionnaire, blood pressure monitoring and a battery of neurophysiological tests: time domain analysis of RR interval variation during normal and deep breathing (DB), Valsalva manoeuvre, and tilt test. By off-line, performed frequency domain analysis of heart rate variation, total power (TP), low frequency band (LF) band, high-frequency (HF) band, and their normalized units were estimated. The neurophysiological measurements were compared to those of 24 healthy controls. The values of time domain variables were pre- and postoperatively lower in patients than in controls. A significant reduction was found in LF band after the implantation. Orthostatic hypotension was present in 45.8% of the patients preoperatively and 12.5% postoperatively. There was no correlation between DBS-related changes of motor function and corresponding neurophysiological measurements, but patients with more than 60% motor improvement had higher time domain parameters' values than the others. STN-DBS offered no considerable impact on autonomic cardiovascular control.

Interictal alterations of cardiovagal function in chronic epilepsy

To assess the function of parasympathetic heart control in patients with epilepsy by means of clinical routine neurophysiology. Seventy-one consecutive epileptic patients (mean age+/-S.D. 37.8+/-12.9 years) with partial or generalized seizures manifested for more than 6 months and receiving various therapeutic regimes and 71 matched for sex and age healthy controls undertook a battery of neurophysiological tests which consisted of sensory conduction of sural nerve; R-R interval variation during normal and deep breathing; Valsalva manoeuvre and tilt test for calculation heart rate changes to respiratory strain and standing. The patient group showed a significant difference in all parasympathetic parameters studied compared to the control group. Overall, 42.2% of patients had abnormal measurement in at least one of the parameters and Valsalva was the most frequently abnormal one (31% of patients). Sural nerve amplitude was significantly lower in the patients than in the controls and its measurements were associated with those of the tilt test. Long epilepsy duration (more than 10 years) and treatment with phenytoin showed a negative effect on data of R-R interval variation during deep breathing. No other correlations between measurements of parasympathetic parameters and epilepsy related characteristics i.e. type and frequency of seizure, monotherapy or combined therapy with seven other antiepileptic medications, were proven. Our results suggested that simple neurophysiological tests, suitable for screening purposes were able to demonstrate suppressed cardiovagal control in epileptic patients and to identify those in need for further analysis of cardiovagal function.

Neurophysiological testing correlates with clinical examination according to fibre type involvement and severity in sensory neuropathy

Objective: To investigate a comprehensive battery of neurophysiological tests for objective evaluation of sensory neuropathies including fibre type involvement and severity, and to determine the relation between neurophysiological data and...

Multimodal Electroneurophysiological Studies of Systemic Lupus erythematosus

The purpose of this study was to obtain electrophysiological documentation of possible involvement of central and peripheral nervous system (CNS and PNS) in systemic lupus erythematosus (SLE) patients even in the absence of neurological manifestations. The study included 30 consecutive patients with SLE and 25 age- and sex-matched volunteers as a control group. They were subjected to neurological and rheumatological tests and an extensive battery of neurophysiological tests, besides Wechsler adult intelligence scale. Overt neurological manifestations were observed in 14 patients (46.7%). Neurophysiological data revealed that 25 patients (83%) had at least 2 abnormal tests; 11 (68.8%) patients of the asymptomatic group and 14 patients (100%) of the symptomatic group with no significant differences between them. Seventeen patients (56.7%) had evidence of PNS dysfunction either in nerves (46.7%) or muscles (10%); 7 of them in the asymptomatic group. Twenty-four patients (80%) had evidence of CNS dysfunction. Twenty-two patients (73%) had abnormalities recorded on electroencephalography; 9 patients in the asymptomatic group and 13 patients in the symptomatic group. Eleven patients (37%) had abnormal values of P100 of visual evoked potential; 5 patients in the asymptomatic group and 6 in the symptomatic group. Eight patients (26.7%) had abnormal latency of wave I of brain stem response; 3 of them in the asymptomatic group. Abnormal prolongation of the P300 component of event-related potentials was recorded in 2 patients (12.5%) of the asymptomatic group, while low IQ was observed in 8 patients of each group. Neurophysiological abnormalities are fairly common in SLE patients whether symptomatic or asymptomatic. The use of such tests favors a true incidence of nervous system involvement, more accurate diagnosis, and may lead to better clinical care before the development of debilitating CNS and PNS changes.

Neurophysiological investigations in multiple sclerosis.

The advent of magnetic resonance imaging techniques has greatly reduced the diagnostic value of neurophysiological tests, particularly evoked potentials, in multiple sclerosis patients, because of the higher sensitivity in revealing subclinical involvement of the central nervous system. Technical progress and new methods of investigating afferent and efferent nervous pathways would seem to increase the sensitivity in detecting neural dysfunction, but the 'clinical gain' is modest at best. More promising is the utilization of neurophysiological tests to quantify the severity of white matter involvement. Transversal and longitudinal studies have demonstrated good correlations between neurophysiological parameters and disability measures, indicating that a battery of neurophysiological tests could be useful in monitoring the disease evolution in single patients and as surrogate endpoints in clinical trials. Further studies are needed for a better definition of the applications of evoked potentials and other neurophysiological techniques. Finally, event-related potentials and advanced electroencephalogram techniques, such as coherence analysis, could provide useful information on the pathophysiology of cognitive dysfunction, so common in multiple sclerosis patients, and with a strong impact on the quality of life.

Neurophysiological tests in neurolupus.

The difficuities in assessing the Central Nervous System (CNS) in the course of Systemic Nervous System (SLE) are weli known. A battery of Neurophysiological tests, including EEG and Multimodal Evoked Potencials was used in order to evaluate CNS disfuntion. Two SLE populations were studied (one with previous neurological symptoms (N = 10) and another without any of the these symptoms (N = 10) and compared with normal controls (N = 14). Tests included Routine EEG, Visual Evoked Potencials (VEP), Flash Evoked Responses (FEP), Auditory P300 (P300) and a Reitan B Test. Both SLE populations showed rather high incidences of abnormalities in FEP and VEP; EEG and P300 had smaller percentages of abnormal records. In spite of stronger and more frequent abnormalities in patient with major symptoms in their past the two SLE could not be differentiated in terms of incidence of abnormal Evoked Potencials Records. Visual Evoked Potencials seem a promising method for the assessment of CNS system disfunction SLE patients.

Combined electrophysiological assessment of the visual system in central serous retinopathy

Six subjects suffering from idiopathic central serous retinopathy were examined during the acute phase using a battery of neurophysiological tests. The records (using skin electrodes) included the electro-oculogram (EOG), the white light electroretinogram (ERG) during various stages of dark and light adaptation, and the flash and pattern reversal visual evoked potentials. Results obtained from the affected eye were compared with those from the healthy eye. The values of the healthy eye were not significantly different from our normal control group. The EOGs of the affected eyes were not significantly different from those of the healthy eyes. The ‘a’ wave of the ERG during light adaptation was significantly ( P<0.05) smaller in the affected eye. The amplitudes of the other components and the latencies of all components were not affected. The latency of the PR-VEP of the affected eye in all subjects was prolonged in comparison with the unaffected eye. In 3 subjects the latency was prolonged by more than 2 S.D.s compared with our control group. The amplitude of the PR-VEP in 5 of our 6 subjects was slightly but significantly ( P<0.02) smaller in the affected eye. There was no correlation between amplitude and latency changes.