P100 Wave Latency Research Articles

Age-related visual signal changes induced by hypoxemic hypoxia: a study on aircraft pilots of different ages.

Exposure to high altitude leads to a series of alterations of higher nervous functions because of hypobaric hypoxia. Sensory systems, mainly the visual one, seem to be particularly involved. This study aimed to assess the effects of hypoxemic hypoxia on the transmission of the visual stimulus simulating a condition of breathing at an altitude of 18,000 feet (5,486 m) through the administration of an air mixture with 10% O2. The subjects involved in the study were 98 pilots of military aircraft (male, acclimated, healthy, 20/20 Uncorrected Visual Acuity (UCVA)/Best Corrected Visual Acuity (BCVA), and aged between 26 and 49 years) divided into 2 groups according to age (A: 26-36 years; B: 37-49 years). The visual evoked potentials were initially recorded at sea level (760 mm Hg) and subsequently at a simulated altitude of 18,000 feet (5,486 m) through the administration of an air mixture with 10% O2 that induced a blood saturation of 80% O2 after 15 minutes. The analysis was carried out using two different kinds of stimulus (15' and 60' of arc). The latency and the amplitude of N-75 (N1) and P-100 (P1) waves have been evaluated. Results obtained from visual evoked potentials were analyzed with Student t-test. In the first group (pilots aged 26-36 years), an increase in both latency and amplitude of P-100 wave was observed and in the second group (pilots aged 37-49 years), an increase was found in latency and a significant reduction in amplitude. The study suggests the existence of a mechanism or a particular anatomic and physiologic condition (probably the neurovascular coupling) that connects the local neuronal activity and the resulting changes in cerebral perfusion. This complex series of events binds together different structures and cell types, and it seems that younger people have a better resistance against the hypoxic insult to the central nervous system because of more efficient compensatory mechanisms.

Objective and subjective examinations for evaluation the degree of drusen‐related optic nerve neuropathy

AbstractPurpose Evaluation of influence of the drusen on optic nerve function. Comparison of various diagnostic methods.Methods 27 patients (54 eyes) with optic nerve drusen (average age: 33 years) and 15 healthy patients (30 eyes; average age: 32 years) have been examined. By all patients full ophthalmological examination, static perimetry (Octopus 301, Zeiss), contrast sensitivity with the sine wave contrast test (SWCT) as well as pattern electroretinography (PERG) and pattern visual evoked potentials (PVEP; Reti‐Port, Roland Consult) were conducted. Statistical analysis was based on Mann‐Whitney U Test and Spearman Test.Results Best Corrected Visual Acuity in all eyes amounted to 0.0 logMAR. In PVEP examination, the eyes with optic nerve drusen have revealed a statistically significantly lower P100 wave amplitude at 1 check size (p = 0,0004) and at 15’ (p = 0,046) as well as longer P100 wave latency at 15’ check size (p = 0,046) than healthy eyes. In PERG the amplitude of N95 wave was statistically significantly lower for eyes with optic nerve drusen than for healthy eyes. Statistically significant, negative correlation between the amplitude of N95 wave PERG and the value of MD factor of static visual field (r = ‐ 0,1003) has been found. No significant differences in degrees of contrast sensitivity have been identified.Conclusion Presence of drusen disturbs optic nerve function. Electrophysiological examinations are a sensitive test in identifying visual neuropathy.

Breast Milk versus Formula Milk and Neuropsychological Development and Sleep

A cohort study including 14000 newborns, about half of them were exclusively breast fed for the first four months of their lives, this percentage dropped down to about 4% by the end of the fourth month of age. One third of these babies were not breast fed at all; 9% of them were identified with a degree of gross motor delay, 6% with fine motor delay by the age of 9 months. The proportion of infants who acquired their milestones overtime increased with exclusivity of breastfeeding. Infants who had never been breastfed were 40-50% more prone to have some sort of motor delay than breast fed infants (10.7% vs 7.3%). These findings did not decrease with adjustment of other confounders, e.g. biological, socioeconomic or psychosocial factors [1]. Neuro-physiological outcomes in breast fed infants was evaluated through flash Visual Evoked Potential (VEP), Brainstem Auditory Evoked Potential (BAEP) and Somato-Sensory Evoked Potential (SSEP) and showed significant prolongation of P-100 wave latencies in formula fed infants, in addition to that, prolongation of absolute waves I, III, V wave latencies of BAEP was also seen in formula fed infants in comparison with breast fed infants. SSEP showed similar findings to VEP and BAEP. This concludes that maturation and brain myelination patterns in breast fed infants is more mature than formula fed infants [2]. Small for Gestational Age (SGA) born babies are at high risk for neuro-developmental delay. Studies have shown that enriched formula fed to term SGA infants improve their growth and their neuro-developmental outcome. A multicenter randomized controlled study in United Kingdom showed that there was no significant intergroup difference in Bayley Mental Development Index (MDI) or Psychomotor Development Index (PDI) scores at 18 months. Though, breast fed infants have significantly higher MDI and PDI scores than formula fed infants. Confounding factors accounted for one third of the resulted association with MDI score and none of the association with PDI score. It is previously reported that enriched formula do have significant effect on enhancing linear growth, though this was not correlated with neurodevelopmental benefit [3]. Breast feeding should be encouraged for best neurodevelopmental outcome in infants born SGA. Behavioral assessment of neonates was done for 83 neonates at their ninth day of life, though special assessment scale “Brazelton Neonatal Behavioral Assessment Scale”. 42 neonates were exclusively breast fed and 42 were formula fed, the study showed that breast fed infants exhibited fewer abnormal reflexes, signs of depression, and withdrawal. This proves that breast feeding

5. Electrophysiological features of peripheral and central nervous system in hereditary neuropathy Charcot Marie Tooth linked to X chromosome

Background Hereditary neuropathy Charcot Marie Tooth linked to X chromosome (CMTX) is the second most frequent hereditary neuropathy (about 10% of all Charcot-Marie-Tooth neuropathies-CMT). CMTX is caused by mutations of gab junction β -1 (GJB1) gene coding connexin 32 protein. This protein is expressed by myelinating Schwann cells in the peripheral nerves and by oligodendrocytes in the central nervous system. We were interested in clinical features of GJB1 gene mutations in the peripheral nerves and central nervous system (acoustic, visual or vestibular pathways), which could be affected subclinically. We were also interested in differencies of electrophysiological results between CMTX males and females. Methods We report an electrophysiological study of 39 CMTX patients (18 M + 21 F) from 10 unrelated families with genetically proven diagnosis. We performed nerve conduction studies (NCS), evoked potentials (BAEP, VEP) and electronystagmography (ENG) to determine whether PNS, CNS or boths pathways were affected. Results The NCS were severly affected in CMTX males than in females. The conduction abnormalities in males fullfiled demyelinating pattern (MCV 32–33 m/s) in majority of them compare to females with intermediate slowing or normal (MCV 41–44 m/s) conduction velocity.The sensory fibers were more severe affected than motor fibers. Brainstem auditory evoked potentials (BAEP) were abnormal in 24 (13 M + 11 F) out of 29 patients (13 M + 16 F). BAEP were severly affected males than females. Visual evoked potentials (VEP) were abnormal in 5 (4 M + 1 F) out of 18 patients (10 M + 8 F), mainly prolonged latency and low amplitude of P100 wave. Electronystagmography (ENG) of 15 patients (7 M + 8 F) detected central abnormalities in 9 patients (4 M + 5 F). Conclusions Electrophysiological testing of peripheral nerves showed severe lesions in males compare to females and sensory fibers were more affected than motor fibers. The majority of CMTX males developed demyelinating type of conduction abnormity compare to normal results or mild axonopathy in CMTX females. BAEP are most sensitive method to detected subclinical lesion of CNS in CMTX patients. BAEP were abnormal in 82%, ENG in 43.7% and VEP in 25% of CMTX patients, mainly in males. The combination of the different modalities of evoked potentials increase the sensitivity of detection of central lesions in CMTX patients. Supported by MZ CR-RVO, FN Motol 00064203 and by IGA grant NT/14348.

Visual Evoked Potentials in Infants With Diffuse Periventricular Leukomalacia

Periventricular leukomalacia (PVL) is characterized by necrosis of the cerebral white matter in the dorsolateral portions of the lateral ventricles. PVL causes motor, sensory, and cognitive deficits. The aim of this study was to analyze the conduction characteristics of the visual pathway in infants with diffuse PVL using visual evoked potentials (VEPs). We studied 11 healthy infants (mean age 3.3 ± 1.3 months) and 17 with diffuse PVL (mean age 2.9 ± 0.8 months and mean gestational age 31.9 ± 3.1 weeks). The N75, P100, and N135 wave latencies; the interwave N75-P100 and P100-N135 latencies; and the N75-P100 and P100-N135 amplitudes were measured in the occipital leads. VEPs were recorded during binocular stimulation at an angle of 120' from the Fz-Oz lead. Healthy children had mean N75, P100, and N135 wave latencies of 84.4 ± 5.8, 143.4 ± 30.6 and 222.9 ± 40.4 ms, respectively. The mean interwave N75-P100 and P100-N135 latencies were 59.0 ± 28.6 and 79.5 ± 13.6 ms, respectively. Compared with the healthy group, infants with PVL had longer N75 and N135 latencies at 92.3 ± 15.3 (P = .05) and 265.0 ms ± 60.3 (P = .05), respectively. The interwave latency P100-N135 (105.5 ± 29.1 ms; P = .017) was longer in children with PVL than in healthy infants. Infants with diffuse PVL had mild alterations in their N75, P100 and, particularly, their N135 latencies. These increases in P100-N135 interwave latencies could be because of damage to the geniculocortical pathways and V2-V3 networks.

Characteristics of the multifocal electroretinogram in type 2 diabetes without clinically apparent retinopathy

Objective To investigate the changes of multifocal electroretinogram (mf-ERG) in type 2 diabetes without clinically apparent retinopathy.Methods Eighteen type 2 diabetes patients (32 eyes) without clinically observed retinopathy and 14 normal control eyes received mf-ERG examination.Results The latency of P1 wave in the ring one,ring two and ring three of diabetes were (48.47 ± 2.33),(31.19 ± 15.53),(15.67 ± 5.73) ms respectively,which had significantly statistical difference with the normal control eyes (t 5.145,2.376,2.276;P＜ 0.05).The amplitude density of P1 wave of temporal retina in diabetes patients was (9.07 ± 2.19) nV/deg2,which was significant different (t=-3.468,P＜0.05) with the normal control eyes (14.13 ± 2.76) nV/deg2.Conclusion The latency of mf-ERG P1 wave is delayed,and the amplitude density of P1 wave of temporal retina is declined in type 2 diabetes patients without clinically apparent retinopathy. Key words: Diabetic retinopathy/diagnosis; Electroretinography

Evaluation of Moderate Closed Head Injury by Visual Evoked Response

Background: Traumatic brain injury (TBI) is a serious public health problem. Even injuries classified as mild which is the most common, can result in persistent neurobehavioural impairment. Diffuse axonal injury is a common finding after TBI, and is presumed to contribute to outcomes, but may not always be apparent using standard neuroimaging. All severities of TBI can result in a degree of axonal damage, while irreversible myelin damage was only apparent for moderate to severe TBI.
 Objectives: To evaluate the effects of moderate closed head injury on visual evoked response (VER) and to assess the changes in VER 6 months later as follow up indices.
 Subjects and methods: This prospective study was conducted in the Department of Neurophysiology /Hospital of Neurosurgery/Baghdad from November 2010 to February 2012, using Esoata Italian machine. Ninety three patients with moderate closed head injury (49 female and 44 male), with an age range from (5 -51) years, with a mean age of (26±11.95) years, were chosen according to Glasgow coma scale (9-12 score) undergo VER and only 86patients will follow up by VER and both were compared to control group of 55 healthy subjects.
 Results: P100 wave latency of visual evoked response (VER) was found to be significantly prolonged (P100= 145.41±9.67 msec.), in patients with moderate head injury at an early measurement after injury as compared to that of the healthy (P100= 97.66±4.58 msec.), whereas, the amplitude of P100 at an early measurements is reduced significantly (2.71± 0.77 µv) when compared to healthy subjects (7.32± 1.62 µv). By 6 months post injury the latency of P100was significantly prolonged (P100=137.19±8.45msec.) when compared to that of control group, while it is significantly reduced when compared to the patients with head injury at an early measurements. However, at 6months post injury the P100 amplitude was significantly increased (amplitude =3.26±0.62μv) when compared to the patients with head injury at an early measurement whereas, significantly reduced when compared to the control group.
 Conclusion: this study revealed that head injury had serious effect on the brain functions reflected by changes in VER which needs long period of time to return to normal levels.

P300 Evoked Potential in Patients with Mild Cognitive Impairment

CONFLICT OF INTEREST: NONE DECLAREDAimThe aim of this study is to present differences of amplitude and latency of P300 wave between examinees with mild cognitive impairment and examinees from the control group.MethodsA cross-section study was performed between April 1st and July 10th 2012, with the diagnosis of mild cognitive impairment as the main criterion for inclusion. In the twenty-two examinees who participated in the research, mild cognitive impairment was confirmed by neuropsychological testing, following which they were subjected to the examination of auditory evoked potentials. The control group consisting of 22 examinees, for which the lack of the same diagnosis was previously ascertained, was also subjected to the examination of auditory evoked potentials. The main findings were the differences in the latency and amplitude size of P300 wave targeted and non-targeted stimuli.ResultsThe latency of P300 wave targeted stimuli in patients with mild cognitive impairment has, in statistical terms, proven to be significantly longer when compared to the control group. The average latency length in those with MCI amounted to 306.18 ms, whereas the latency in the control group came to 295.95 ms. Similarly, the latency length of non-targeted stimuli turned out to be statistically higher, with the length of 320.00 ms in the former group, and 301.36 ms in the latter. Amplitudes in patients with mild cognitive impairment were lower in comparison to the control group, with extremely low amplitudes recorded in 36.36% of patients.ConclusionIn patients with mild cognitive impairment extended latency and lower amplitude of P300 wave are recorded.

A comparison of cognitive functions in non-hypoxemic chronic obstructive pulmonary disease (COPD) patients and age-matched healthy volunteers using mini-mental state examination questionnaire and event-related potential, P300 analysis.

Objective:To assess sub-clinical cognitive dysfunctions in stable chronic obstructive pulmonary disease (COPD) patients having no hypoxemia vs. age-matched healthy volunteers using (i) an electrophysiological test: Auditory event related potential, P300 test and (ii) a questionnaire tool: Mini-mental state examination (MMSE) questionnaire.Materials and Methods:Eighty male subjects were included: 40 stable COPD patients (smoking history >20 pack years) and 40 healthy volunteers (HVs). Age, duration of illness, smoking pack years, and spirometric indices were assessed. MMSE scores were evaluated in these groups. Latency of P300 wave and amplitude of P300 wave were studied in both groups to detect P300 abnormalities in COPD group. Correlations of P300 abnormalities with patient characteristic parameters and MMSE scores were assessed. In addition, individual COPD patients having significant cognitive dysfunctions beyond cut-off value of 99th percentile of HVs were analyzed.Results:We observed significantly prolonged P300 latency (P < 0.001) and decreased P300 amplitude (P < 0.001) in COPD group. MMSE scores were significantly reduced in COPD group (P < 0.001). 10/40 COPD patients had prolongation of P300 latency, and 27/40 COPD patients had reduced MMSE scores beyond 99th percentile of HV. However, we did not observe any statistically significant correlation between P300 abnormalities and patients’ characteristics or MMSE scores (P > 0.05 for all).Conclusions:Our study explores cognitive dysfunctions in stable COPD patients with no hypoxemia. This study highlights the relative importance of using MMSE and P300. Cognitive dysfunctions were detected both by MMSE and P300; however, MMSE abnormalities were more frequent compared to P300 abnormalities (27/40 vs. 10/40) in COPD patients.

1088 – ECT and information processing in patients with treatment-resistant psychiatric disorders assessed by event-related potential P300

The study of non-memory cognitive functions after ECT has been relatively neglected. Event-related potentials (ERP) are thought to reflect some cognitive processes. ERP P300 is a sensitive indicator of disturbances of attentional and working memory processes. Aim of this study was to examine the effect of course of ECT on auditory ERP P300. P300 potential was recorded in 22 patients. 12 patients had schizophrenia spectrum disorders and 10 patients had various mood disorders. Mean age of patients was 40±13 years (from 22 to 72 years). ERPs were recorded before the first ECT procedure and after the last ECT. Recordings were made at Fz, Cz and Pz electrode sites. Peak-to-peak (N2-P3) amplitude and latency of P300 wave were analyzed. Correlation between P300 parameters, clinical symptoms (measured using PANSS, MADRS, HAM-D scales) and parameters of ECT procedure - delivered energy, seizure energy index (SEI) and duration of seizure - was evaluated. After ECT clinical symptoms have improved. There was also a statistically significant increase in P300 amplitude. Increase was greater in the 20-39 years old patient group. Decrease in P300 latency was insignificant. Correlation between P300 latency and SEI, and between P300 amplitude and delivered energy was more reliable in the mood disorders group. According to HAM-D the improvement of depression symptoms correlates with the decreased latency and increased amplitude of the P300 potential. ECT may improve information processing in patients with treatment-resistant schizophrenia spectrum disorders and mood disorders as assessed by event-related potential P300.

An electrophysiologic study of stereotaxis and vena caudalis transplantations of bone marrow mesenchymal stem cells in treatment of spinal cord injury in rats

Objective To compare the effects of stereotaxis and vena caudalis transplantations of bone marrow mesenchymal stem cells(BMSCs) in the treatment of spinal cord injury (SCI) in rats.Methods SD rat BMSCs were isolated,purified and proliferated in vitro.Forty-five adult female Wistar rats were used to establish SCI models with aneurysm clips before they were randomly divided into 3 even groups:a control group and stereotaxis and vena caudalis transplantation groups.The SCI was not treated in the control group.Seven days after the SCI,the suspension with BrdU-labeled BMSCs was injected into the SCI site in the stereotaxis transplantation group and into the body through the caudal vein in the vena caudalis transplantation group.Neural electrophysiologic tests were used to compare the effects of the 2 different ways of BMSCs transplantation on the neural recovery of the injured spinal cord in rats.Results There were no significant differences among the 3 groups before establishment of the SCI model and 7 days after the establishment of SCI model regarding the latency and amplitude of evoked potentials (P ＞ 0.05).Thirty days after the establishment of SCI model all the rats showed significantly reduced latency and significantly increased amplitude (P ＜ 0.05).The BMSCs transplantation groups showed significantly shorter motor evoked potential latency and shorter somatosensory evoked potential P1 wave latency than the control group (P ＜ 0.05).The recovery of motor evoked potentials was significantly slower in the vena caudalis transplantation group than in the stereotaxis transplantation group (P ＜ 0.05).Conclusions Transplanted BMSCs can survive,migrate in the host spinal cord,leading to significant recovery of neurological function in SCI rats.With the same amount of BMSCs,stereotaxis transplantation may be more effective than vena caudalis transplantation in the SCI treatment in rats. Key words: Bone marrow cells; Spinal cord injury; Stem cell transplantation; Evoked potentials

Epidural Administration of Magnesium Sulfate in the Rabbit: Can It Induce Motor and Sensory Blockade?

We investigated whether epidural magnesium sulfate administration can produce motor blockade and/or sensory blockade in rabbits. Control animals (group C) received 1.2 ml isotonic saline, group M received 1 ml 15% (150 mg) magnesium sulfate and 0.2 ml isotonic saline (to flush the catheter), while group L received 1 ml 1% lignocaine and 0.2 ml isotonic saline. On the 1st day, somatosensory evoked potentials (SEPs) were recorded; on the 2nd day, motor blockade was evaluated, and the heart rate, mean arterial pressure (MAP), serum PaCO2, and serum magnesium level were measured. Compared with groups C and M, the MAP in group L was significantly reduced at the 2nd–5th, 15th, and 30th min. Significant motor blockade was found only in group L. No significant difference was found in a comparison of the latencies and amplitudes of SEP waves P and N between groups. Comparisons within the groups showed that the P1 wave latency in group C significantly increased at the 15th min, while the latency of wave N1 showed a significant decrease at the 60th min in group M. The latencies of the N1 and P1 waves showed significant increases at the 5th min in group L. Thus, our study showes that epidural administration of 150 mg magnesium sulfate in rabbits produces no motor or sensory blockade.

Optic nerve assessment identifies biomarkers of axonal pathology in multiple sclerosis

Our aim was to identify possible correlations between physical disabilities assessed by expanded disability status score (EDSS) and neurodegenerative process measured by retinal nerve fibers thickness, and also with demyelization process measured by visual evoked potential with P100 wave latency at optic nerve level on patients diagnosed with multiple sclerosis (MS). This study aimed to find a structural biomarker at central nerve system (CNS) level which could correlate with clinical disability. The optic nerve is an accessible structure of CNS easy to investigate. We analyzed a population of 111 patients diagnosed with different clinical forms of multiple sclerosis based on 2005 revised Mc Donald criteria, for whom we assessed clinical disability by EDSS, and by different subscales of multiple sclerosis composite (MSFC) as timed to walk 25 foot (TW25F) and nine hole peg test (9HPT). Optic nerve involvement was assessed for each eye measuring visual acuity (VA) (Snellen chart), P100 wave latency by visual evoked potential (VEP) and retinal nerve fiber layer thickness (RNFL) by optical coherence tomography (OCT). The medium age of our population was 38.09 and the medium EDSS was 3.3. – 76 out of 111 were women. 79 patients were diagnosed with relapsing remitting (RR) MS, 7 with clinically isolated syndrome (CIS), the other were diagnosed with progressive form of MS: 7 with primary progressive MS and one with primary progressive with relapse MS. We obtained positive correlations, and statistically significant between EDSS and 9HPT for dominant hand (r=0.58, p = 0.0001) and also for non dominant hand (r = 0.66, p = 0.0001) using Pearson correlation. EDSS score correlates statistically significant with P100 wave latency and visual acuity for both eyes using Pearson correlation, so we obtained negative correlation between EDSS and VA for right eye (r = -0.45, p = 0.0001), and for left eye (r = -0.49, p = 0.0001). We also observed statistically significant positive correlation between EDSS and P100 wave latency for right eye (r = 0.405, p = 0.0001), and left eye (r = 0.400, p = 0.0001). RNFL doesn’t correlate with EDSS, VA or P100 wave latency. Using chi square correlation between EDSS score (we choose a cut of value of 3) and pathological value of RNFL by OCT we didn’t obtain a statistical significant result. The results were : for right eye phi = 0.01, p = 0.9), and for left eye (phi = -0.1, p = 0.3). Similar results were obtained for EDSS of 4.0. The results were: for right eye (phi=-0.009, p= 0.9), and for left eye (phi = 0.017, p = 0.8). In conclusion, in order to understand the pathology of multiple sclerosis the anterior optic nerve pathway offers an attractive model. Optic nerve assessment can be realized through non-invasive complementary methods. Functional and structural data of optic nerve can be obtained by VA measurement, VEP and OCT assessments. Our study showed that axonal pathology of the optic nerve (part of CNS exclusively composed by white matter) correlates with clinical disability measured by EDSS, suggesting that P100 latency is a functional biomarker of the disease. A prospective study to validate such a marker of the progression of the disease is needed.

The Relationship Between Optical Coherence Tomography and Visually Evoked Potentials and Disability in Patients with Multiple Sclerosis

Due to the absence of myelin in retinal neurons, they represent a good structure to exhibit axonal degeneration in multiple sclerosis. Optical coherence tomography is a relatively new technique that shows axonal damage by measuring the retinal nerve fibre layer. The aim of this study is to investigate whether there is a relationship between OCT and visually evoked potentials and disability related to the disease in patients with multiple sclerosis. The study included 30 patients diagnosed as relapsing remitting multiple sclerosis, 10 as secondary progressive multiple sclerosis, and 20 control subjects. The P100 wave was obtained with pattern visually evoked potential. Optical coherence tomography was used to measure the retinal nerve fibre layer thickness. The findings were compared with Expanded Disability Status Scale scores in the patient groups. The secondary progressive group had thinner nerve fibre layer than the controls (P < 0.001). In both patient groups, P100 wave latency was more prolonged than the controls and this result was statistically significant (P < 0.001). In the secondary progressive group, the reduction in visually evoked potential amplitude was also significant (P < 0.001). No relationship between the disability of either multiple sclerosis group and optical coherence tomograpy and visually evoked potential findings was found (P > 0.05).

Comparison of latency of P100 wave in children demonstrating some pathological disorders

AbstractPurpose A goal of the present paper was an assessment of usefulness of latency of P100 wave in describing few pathological disorders in children. The study group comprised 268 children, including 68 with cytomegaly (CM), 59 with myelomeningocele (MM) , 69 with purulent meningitis(PM) and 73 with Down’s syndrome (DS). The control group consisted of 592 healthy children.Methods Registrations were performed using Visual Evoked Potentials for each patient, stored on data bank and evaluated automatically with manual correction. Collected values of P100 wave’s latency were analyzed using typical statistical tools (t‐test contained in STATISTICA‐data analysis software system. StatSoft, Inc. 2011, version 10. www.statsoft.com).Results The comparison performed in regard to the group‐mean latencies of the analyzed P100 wave between the control group and the four studied groups revealed statistically significant differences (p&lt;0.0001). There were also statistically significant differences in the mean P100 latency between DS group and CM and PM groups (p&lt;0.0001). Evaluation of the mean latencies in three groups (CM, MM and PM) did not reveal statistically significant differences (p&gt;0.05).Conclusion The results show the differences in mean latency of P100 wave between normal subjects and children with pathological disorders. In children with Down’s syndrome observed abnormalities were smaller than in other 3 groups.

Detection of a novel premature stop codon in the OPA1 gene in autosomal dominant optic atrophy

AbstractPurpose Autosomal dominant optic atrophy (ADOA) is a genetically heterogeneous disease, with OPA1, OPA4, and OPA5 representing the main ADOA loci. The aim of the study was to identify genetic etiology of inherited optic neuropathy in a Polish family.Methods We report on a 2‐generation Polish family with ADOA in which nine family members are affected. MRI and detailed ophthalmological examination with visual field and electrophysiological testing were performed. DNA was obtained from blood samples and linkage to known ADOA loci as well as sequencing of 29 OPA1 exons were conducted. Amplified fragments were analyzed on an automatic DNA sequencer.Results MRI and ophthalmological examination confirmed the diagnosis of bilateral optic neuropathy. Pattern visual evoked potentials (PVEP) presented delayed P100 wave latency, reduced N75/P100 amplitude and abnormal morphology of waves. Pedigree analysis demonstrated a dominant mode of inheritance. Linkage studies allowed the exclusion of OPA4 and OPA5 loci but revealed linkage to the major OPA1 locus in the investigated family. Sequencing of the OPA1 gene identified a novel C‐to‐T transiton in exon 2 prediciting a premature stop codon (Q31X). The mutation co‐segratated with the phenotype in this family. No other alteration was found in the OPA1 gene.Conclusion Occurrence of the premature termination codon at the beginning of the transcript strongly suggest that ADOA in the investigated family is a consequence of OPA1 haploinsufficiency. The novel variant broadens the spectrum of the reported OPA1 mutations causing ADOA.

Adeno‐associated virus‐mediated gene delivery of the human ND4 complex I subunit in rabbit eyes

To assess intravitreal injection dose and safety of recombinant adeno-associated virus-mediated gene delivery of human NADH dehydrogenase subunit 4 (ND4) in rabbit eyes. An open reading frame for human ND4 or adeno-associated virus-green fluorescent protein were fused to the mitochondrial targeting sequence and packed into separate adeno-associated virus capsids. Rabbits of three treatment groups were administered 0.1 mL adeno-associated virus-ND4, 0.1 mL adeno-associated virus-green fluorescent protein or 0.1 mL vehicle via intravitreal injection, respectively. The safety of recombinant adenoassociated virus-mediated gene delivery of human ND4 in rabbit eyes was assessed with a slit-lamp microscope and direct ophthalmoscope, measurements of intraocular pressure and flash visual evoked potential, and optical coherence tomography. The mRNA and protein expressions of human ND4 in the retina of rabbits were determined with real-time polymer chain reaction (PCR), immunofluorescence and Western blot. No complications occurred in any of the three treatment groups after the intravitreal injection. At 1-month post-injection, no significant difference in the mean thickness of retinal nerve fibre layer was found among the three groups. Results of the visual evoked potential test showed that there was no difference in the latency of the visual P100 wave among the three groups. Real-time PCR, immunofluorescence and Western blot analyses verified the expressions of ND4 and green fluorescent protein in the retinal nerve fibre layer. Intravitreal injection of adeno-associated virus-ND4 expression vectors was effectively and safely performed in our study. The data on the dose and method of intravitreal injection from our study will provide a valuable reference for clinical intravitreal injection of adeno-associated virus-ND4 for the treatment of Leber's hereditary optic neuropathy.

Evaluation of pattern-reversal visual evoked potential in patients with neuromyelitis optica

Background: The visual evoked potential (VEP) is used in the evaluation of multiple sclerosis (MS) patients, showing a delay in P100 wave latency with no changes in amplitude in 60–100% of cases. In the last decade, the recurrent form of neuromyelitis optica (NMO) has been recognized, and clinically characterized by acute events of transverse myelitis (TM) and optic neuritis (ON), differing from MS in clinical and laboratory criteria. Despite these differences, so far, the VEP parameters described in MS have been used in the evaluation of patients with NMO. The objective of this study was to investigate VEP responses in NMO. Methods: Patients with NMO underwent pattern-reversal visual stimulation. Nineteen patients were selected for the study. Results: Among the 38 eyes examined, 18 (47.4%) had no visual evoked responses and 13 (34.2%) had a reduction of P100 wave amplitude with normal latency. Only two (5.3%) had the pattern described in MS and five (13.2%) were normal. Conclusion: Evaluation of VEP in patients with definite NMO revealed a pattern that is different from that of MS in 81.6% of eyes examined, characterized by the absence of responses, or decreased amplitude with normal latency.

Aging effect in pattern, motion and cognitive visual evoked potentials

An electrophysiological study on the effect of aging on the visual pathway and various levels of visual information processing (primary cortex, associate visual motion processing cortex and cognitive cortical areas) was performed. We examined visual evoked potentials (VEPs) to pattern-reversal, motion-onset (translation and radial motion) and visual stimuli with a cognitive task (cognitive VEPs – P300 wave) at luminance of 17cd/m2. The most significant age-related change in a group of 150 healthy volunteers (15–85years of age) was the increase in the P300 wave latency (2ms per 1year of age). Delays of the motion-onset VEPs (0.47ms/year in translation and 0.46ms/year in radial motion) and the pattern-reversal VEPs (0.26ms/year) and the reductions of their amplitudes with increasing subject age (primarily in P300) were also found to be significant. The amplitude of the motion-onset VEPs to radial motion remained the most constant parameter with increasing age. Age-related changes were stronger in males.Our results indicate that cognitive VEPs, despite larger variability of their parameters, could be a useful criterion for an objective evaluation of the aging processes within the CNS. Possible differences in aging between the motion-processing system and the form-processing system within the visual pathway might be indicated by the more pronounced delay in the motion-onset VEPs and by their preserved size for radial motion (a biologically significant variant of motion) compared to the changes in pattern-reversal VEPs.

Evolución neurológica, neuropsicológica y oftalmológica tras un año de suplementación con ácido docosahexaenoico en pacientes fenilcetonúricos

INTRODUCTION. Phenylketonuria (PKU) is an autosomal recessive metabolic disease caused by a deficiency of phenylalanine hydroxylase. The dietary therapy for the effective management of PKU, in particular the restriction of high-protein foods of animal-origin, compromises patients' intake of fat and distorts the n-3:n-6 ratio of essential fatty acids in the diet. This deficiency can contribute to neurological and visual impairment. AIM. To evaluate changes in white matter alterations, visual evoked potential (VEP) latencies and performance in executive and motor functions in a group of early and continuously treated PKU patients after supplementation with docosahexaneoic acid (DHA). PATIENTS AND METHODS. We selected 21 PKU patients with early diagnosis (age range: 9-25 years), on a Phe-restricted diet and supplemented with PKU formula. Inclusion criteria were: low erythrocyte DHA values, prolonged P100 wave latencies in VEP and/or presence of white matter hyperintensities on brain magnetic resonance imaging (MRI), and intellectual quotient > 80. All patients were treated with DHA (10 mg/kg/day) for 12 months. Assessment was conducted at baseline and after 12 months of treatment, and included biochemical parameters, brain MRI, VEP, ophthalmologic evaluation and neuropsychological tests. RESULTS AND CONCLUSION. All the patients normalized the DHA levels after supplementation. Improvement in the P100 wave latencies, and fine motor skills was significant. No significant improvement in the other explorations was evident after supplementation. Further investigations seem advisable to establish a cause-effect relationship between DHA treatment and the slight improvement observed in some neurological functions.