Sándor Beniczky

Diagnostic usefulness and duration of the inpatient long-term video-EEG monitoring: Findings in patients extensively investigated before the monitoring

Inpatient long-term video-EEG monitoring (LTM) is an important diagnostic tool for patients with seizures and other paroxysmal behavioural events. The main referral categories are diagnosis (epileptic versus non-epileptic disorder), seizure classification and presurgical evaluation. The diagnostic usefulness of the LTM varies considerably (19-75%) depending on how this was defined and on the selection of the patients. The purpose of this study was to assess the diagnostic usefulness and the necessary duration of the LTM for the referral groups, in patients extensively investigated before the monitoring. An LTM was considered diagnostically useful when it provided previously not reported, clinically relevant information on the paroxysmal event. For the presurgical group, reaching a decision concerning surgery was an additional requirement. We reviewed data from 234 consecutive LTM-sessions (221 patients) over a 2-year period. In 44% of the cases the LTM was diagnostically useful. There were no significant differences concerning diagnostic usefulness among the main referral groups: diagnostic (41%), classification (41%) and presurgical (55%). Diagnostic usefulness did not differ among the age groups either. The duration of the successful LTM-sessions was significantly longer in the presurgical group (mean: 3.5 days) than in the diagnostic and classification groups (2.4 and 2.3 days, respectively). We conclude that LTM is a valuable diagnostic tool even in patients extensively investigated before the monitoring, and is equally effective in the referral and age groups. However, patients referred for presurgical evaluation need considerably longer LTM, and this should be taken into account when planning the resources and calculating the costs.

The effects of reward and punishment contingencies on decision-making in multiple sclerosis.

Many patients with multiple sclerosis (MS) show cognitive and emotional disorders. The purpose of this study is to evaluate the role of contingency learning in decision-making in young, non-depressed, highly functioning patients with MS (n=21) and in matched healthy controls (n=30). Executive functions, attention, short-term memory, speed of information processing, and selection and retrieval of linguistic material were also investigated. Contingency learning based on the cumulative effect of reward and punishment was assessed using the Iowa Gambling Test (IGT). In the classic ABCD version of the IGT, advantageous decks are characterized by immediate small reward but even smaller future punishment. In the modified EFGH version, advantageous decks are characterized by immediate large punishment but even larger future reward. Results revealed that patients with MS showed significant dysfunctions in both versions of the IGT. Performances on neuropsychological tests sensitive to dorsolateral prefrontal functions did not predict and did not correlate with the IGT scores. These results suggest that patients with MS show impaired performances on tasks designed to assess decision-making in a situation requiring the evaluation of long-term outcomes regardless of gain or loss, and that this deficit is not a pure consequence of executive dysfunctions.

Complex hallucinations following occipital lobe damage

Visual hallucinations may accompany many neurological and psychiatric disorders. A common localization principle is that lesions to the early sensory cortices lead to elementary hallucinations, whereas complex perceptual experiences are related to the pathology of higher‐level cortical regions. We report the case of a patient who experienced complex, non‐stereotyped, multimodal (visual and somatosensory) hallucinations following an acute ischaemic vascular lesion in the right medial occipital lobe. This illustrates that the phenomenology of hallucinations not necessarily reflects the exact localization of cerebral pathology. Instead, the damaged area may serve as a focus of an abnormally activated neuronal network.

Proteomic Analysis of Cerebrospinal Fluid in a Fulminant Case of Multiple Sclerosis

Multiple Sclerosis (MS) is a chronic disease, but in rare fulminant cases rapid progression may lead to death shortly after diagnosis. Currently there is no diagnostic test to predict disease course. The aim of this study was to identify potential biomarkers/proteins related to rapid progression. We present the case history of a 15-year-old male MS patient. Cerebrospinal fluid (CSF) was taken at diagnosis and at the time of rapid progression leading to the patient’s death. Using isobaric tag labeling and nanoflow liquid chromatography in conjunction with matrix assisted laser desorption/ionization time of flight tandem mass spectrometry we quantitatively analyzed the protein content of two CSF samples from the patient with fulminant MS as well as one relapsing-remitting (RR) MS patient and one control headache patient, whose CSF analysis was normal. Seventy-eight proteins were identified and seven proteins were found to be more abundant in both fulminant MS samples but not in the RR MS sample compared to the control. These proteins are involved in the immune response, blood coagulation, cell proliferation and cell adhesion. In conclusion, in this pilot study we were able to show differences in the CSF proteome of a rapidly progressing MS patient compared to a more typical clinical form of MS and a control subject.

Dissociation between Attentional Set Shifting and Habit Learning: a Longitudinal Case Study

We report a patient (ST) with predominant damage to the right neostriatum, caused by a rare cerebral angiitis. The testing procedure was focused on attentional set shifting (Wisconsin Card Sorting Test: WCST) and habit learning (probabilistic classification learning; PCL). ST showed impairments in the WCST, digit span backward, alphabet span, and PCL procedures, whereas he exhibited spared IQ, short-term verbal memory, object recognition, episodic and semantic memory. After 1 month of steroid therapy, there was a significant improvement in the WCST, digit span backward and alphabet span tests, whereas PCL remained severely impaired. The three control patients with damage to the parietal lobe displayed normal learning rates in PCL. These results suggest that separate frontostriatal mechanisms exist for attentional set shifting and habit learning.

Somatosensory evoked potentials correlate with genetics in Huntington's disease

Abnormalities of somatosensory evoked potentials (SEPs) have been reported in Huntingtons disease, a neuropsychiatric disorder caused by the expansion of a CAG trinucleotide repeat. The aim of our study was to determine the relationship between these electrophysiological changes and the length of the nucleotide repeat. We found a striking correlation between the decrease in the early component amplitudes (N20 and N30) of the median nerve SEP and the repeat length, suggesting that these SEP alterations are indeed related to the genetically determined pathological process. The cortical components of the tibial nerve SEP exhibited a dram-atic alteration in the patient group and were the only SEP changes found in the group of asymptomatic carriers of the mutation, being more sensitive than the median nerve SEPs.

The effect of sleep deprivation on median nerve somatosensory evoked potentials

The purpose of the study was to determine the effect of one nights sleep deprivation on the early and middle-latency median nerve (MN) somatosensory evoked potentials (SEPs). In 20 healthy volunteers, SEPs in response to electrical stimulation of the MN at the wrist were recorded for the 100-ms post-stimulus period, before and after one night of sleep deprivation. The P14 latency was significantly prolonged after sleep deprivation. We found significant increases in the amplitudes of the early parietal (N20-P24) and the frontal middle-latency (P45-N60) components following sleep deprivation. Our results indicate that somatosensory processing is altered after sleep deprivation.

Effect of medication withdrawal on the interictal epileptiform EEG discharges in presurgical evaluation

Medication withdrawal (MW) is an important method of provoking seizures and activating epileptiform EEG activity during the diagnostic work-up of patients evaluated for epilepsy surgery. Previously it was suggested that MW might influence the seizure-type and activate cortical areas otherwise not producing epileptiform discharges, leading to a false localization of the irritative zone. In order to investigate this we reviewed 42 consecutive cases of MW, of 36 patients, during a 3-year period. We compared seizure frequency, seizure-types and the localization of interictal epileptiform discharges before and after MW. Seizure frequency was significantly higher after MW. In the whole group we found an increase in seizure propagation: the proportion of the complex partial seizures and secondarily generalised seizures increased, while the proportion of the simple partial seizures decreased following MW. In one-third of the patients the interictal EEGs after the MW were different from those recorded before the MW. However, in these discordant cases the EEG findings after the MW (and not before the MW) were concordant with the seizure onset zone and the lesional zone. We conclude that MW is an effective and reliable seizure provoking method, and it does not lead to false localization of the irritative zone.

Postictal inhibition of the somatosensory cortex

Transient suppression of the motor cortex and of the speech areas cause well-described postictal phenomena following seizures involving the respective cortical areas. Pain is a rare symptom in epileptic seizures. We present a patient with painful tonic seizures in the left leg. The amplitude of the cortical component of the somatosensory evoked potential following stimulation of the left tibial nerve was reduced immediately after the seizure. Our findings suggest that the excitability of the sensory cortex is transiently reduced following a seizure involving the somatosensory area.

Lateral interactions and speed of information processing in highly functioning multiple sclerosis patients.

Visual impairment is a common feature of multiple sclerosis. The aim of this study was to investigate lateral interactions in the visual cortex of highly functioning patients with multiple sclerosis and to compare that with basic visual and neuropsychologic functions. Twenty-two young, visually unimpaired multiple sclerosis patients with minimal symptoms (Expanded Disability Status Scale <2) and 30 healthy controls subjects participated in the study. Lateral interactions were investigated with the flanker task, during which participants were asked to detect the orientation of a low-contrast Gabor patch (vertical or horizontal), flanked with 2 collinear or orthogonal Gabor patches. Stimulus exposure time was 40, 60, 80, and 100u2009ms. Digit span forward/backward, digit symbol, verbal fluency, and California Verbal Learning Test procedures were used for background neuropsychologic assessment. Results revealed that patients with multiple sclerosis showed intact visual contrast sensitivity and neuropsychologic functions, whereas orientation detection in the orthogonal condition was significantly impaired. At 40-ms exposure time, collinear flankers facilitated the orientation detection performance of the patients resulting in normal performance. In conclusion, the detection of briefly presented, low-contrast visual stimuli was selectively impaired in multiple sclerosis. Lateral interactions between target and flankers robustly facilitated target detection in the patient group.