Epileptic syndromes: differential treatment in infants, children, and adolescents.

This paper proposes therapeutic guidelines for the management of some epileptic syndromes in infants, children, and adolescents, based on available medical literature and clinical practice in the French Community of Belgium. The guidelines address both epileptic encephalopathies (West syndrome, Lennox-Gastaut syndrome, and Dravet syndrome) and idiopathic epilepsies (typical absence seizures, epilepsy with centro-temporal spikes and juvenile myoclonic epilepsy).

Mismatch negativity (MMN) evoked by sound duration contrasts: an unexpected major effect of deviance direction on amplitudes.

OBJECTIVE: Verify and explore unexpected results suggesting an effect of deviance direction (shorter or longer deviants) on the amplitude of MMNs evoked by sound duration contrasts. METHODS: MMNs were recorded using the oddball paradigm on ten adults. Four standard stimulus durations (100, 150, 200 and 250ms) were used and deviants were 50% shorter or longer. Behavioral data (hit rates, d', and reaction times) were collected after the electrophysiological sessions. RESULTS: MMNs were larger for short than for long deviants. There was no effect on MMN latencies. Hit rates and d' data were almost at ceiling level for all conditions even for the longest standard - long deviant combination in which the MMN was abolished. CONCLUSIONS: We argue that the deviance direction effect on MMN amplitudes can be explained by the delay between the moment of deviance detection and the end of the deviance quantification process. SIGNIFICANCE: A major effect of deviance direction on amplitudes was confirmed. This effect, which was confined to electrophysiological data, is to be taken into account when using duration contrasts to probe the processing of temporal information.

[Safety and efficacy of multiple subpial transections: report of a consecutive series of 30 cases]. / Sécurité et efficacité des trans-sections sous-piales multiples: analyse d'une série consécutive de 30 patients.

PURPOSE: To present our results using multiple subpial transections (MST) for the treatment of pharmacologically refractory epilepsy (PRE) with epileptogenic foci in eloquent areas. METHOD: Between January 2003 and March 2006, we treated 33 patients with PRE with epileptogenic foci in eloquent areas by MST "in rays", either isolated (MSTs group) or completing resection or disconnection of other cortical areas (MST+ group). Our first 30 patients had a follow-up of at least 24 months: eight in the MSTs group and 22 in the MST+ group. Four postoperative grades were distinguished based on a modified Engel classification: seizure-free (100% seizure reduction equals to Grade I), substantial significant seizure reduction (75% to 99% seizure reduction equals to Grade II), moderate significant reduction (50% to 74% seizure reduction equals to Grade III) and finally no significant reduction (seizure reduction less than 50% equals to Grade IV). RESULTS: In the MSTs group, two patients (25%) were in grade I and five (62%) in grade II or III. In the MST+ group, six patients (27%) were in grade I and 13 (59%) in grade II or III. All patients showed some seizure reduction and some improvement in behavior or cognitive function with no permanent neurological deficit. CONCLUSION: This series supports the notion that multiple subpial transections are associated with a significant seizure reduction (in 86.6% of the cases reported herein) and that the risk of permanent neurological deficit can be very low.

The epileptic syndromes with continuous spikes and waves during slow sleep: definition and management guidelines.

The authors propose to define the epileptic syndromes with continuous spikes and waves during slow sleep (CSWS) as a cognitive or behavioral impairment acquired during childhood, associated with a strong activation of the interictal epileptiform discharges during NREM sleep--whatever focal or generalized--and not related to another factor than the presence of CSWS. The type of syndrome will be defined according to the neurological and neuropsychological deficit. These syndromes have to be classified among the localization-related epileptic syndromes. Some cases are idiopathic and others are symptomatic. Guidelines for work-up and treatment are proposed.

Analysis of EEG tracings in frequency and time domain in hepatic encephalopathy.

Spectral EEG analysis in hepatic encephalopathy (HE) is usually performed disregarding the effect of epoch length, statistical errors and equipment noise. A study on these items was carried out. In addition, spectral analysis and a new analysis, performed in time domain, were compared in the assessment of HE. The EEG tracings of 73 cirrhotic patients with HE were analyzed. Artifact-free periods of about 1 min were selected. Equipment noise was measured by short-circuiting all the electrodes. The equipment noise was notable below 1.5 Hz; the best epoch length was 4s and the statistical errors were minimal for the band with the highest relative power. Nineteen per cent of the tracings were unstable. The spectral values were found to be related to liver function and to the degree of HE, whereas the relationship with psychometric variables was poor. The indexes computed by time-domain analysis were found to be better related to psychometric findings. We have provided information on the optimisation of spectral EEG analysis and presented a time-domain analysis giving results related to psychometric tests and liver function.

Guidelines for recognition and treatment of the psychoses associated with epilepsy.

Epilepsy and psychiatric diseases are frequent comorbidities. Psychoses in patients with epilepsy have special physiopathology and several clinical presentations and prognoses. Their treatments are also specific, according to the specific diagnosis. This paper represents the summary of a consensus meeting held in November 2003 by a Belgian French-speaking group of neurologists, neuropediatricians and psychiatrists and proposes guidelines for the recognition and treatment of those entities.

Therapeutic issues in women with epilepsy.

Approximately 20% of people with epilepsy are of childbearing potential and about 3 to 5 births per thousand will be to women with epilepsy. Both epilepsy and antiepileptic drugs can cause specific problems in women and embryos (less than 8 weeks of gestational age) or foetuses (more than 8 weeks of gestational age). The aim of this paper is to discuss therapeutic issues for the management of women with epilepsy: initiation of antiepileptic therapy, contraception, pregnancy, breast feeding and menopause. Some fertility issues are also discussed.

No evidence of auditory dysfunction in guinea pigs immunized with myelin P0 protein.

Recent data have focused on the peripheral nerve myelin glycoprotein P0 as a putative autoantigen involved in the autoimmune etiology of some cases of Meniere's disease, idiopathic sensorineural hearing loss and sudden deafness. To determine whether antibodies to myelin P0 can alter cochlear function, 13 healthy guinea pigs were immunized with purified porcine myelin P0 while 10 controls were injected with saline water. The animals were then evaluated for evidence of evolving inner ear disease using immunological, electrophysiological and morphological methods. Twenty-six experimental ears were tested weekly with a brainstem auditory evoked potential technique for a period of 4 months and were compared to 20 control ears. Uniformly, all P0-sensitized guinea pigs showed antibodies to myelin protein P0 as evidenced by ELISA. Clinical signs of inflammatory demyelination were not discernible in P0-sensitized guinea pigs and all the animals were qualitatively normal. No significant increase of evoked potential thresholds was found in the P0-sensitized animals when compared to controls (P>0.05). Peak latencies of waves I, II, III, IV and V and inter-peak latencies in P0-sensitized guinea pigs did not significantly differ from those of controls (P>0.05). Histological sections of inner ear and peripheral nerves were free of disease in both groups. These findings indicate that the sole presence of antibodies to myelin P0 in the sera of guinea pigs or patients suspected of having autoimmune inner ear diseases is unlikely to elicit auditory abnormalities and that additional factors are necessary for the pathogenic development of these disorders.

Spectral versus visual EEG analysis in mild hepatic encephalopathy.

OBJECTIVE: Spectral EEG analysis has been claimed to reduce subjective variability in EEG assessment of hepatic encephalopathy and to allow the detection of mild encephalopathy. METHOD: To test such assumptions, 43 digital EEG were recorded in 32 cirrhotics without overt encephalopathy or with grade 1 overt encephalopathy; 7 patients were re-tested (2-5 times) in their follow up. All patients underwent psychometric assessment. Nineteen controls were considered. EEG were blindly evaluated by two electroencephalographers and by spectral EEG analysis performed according to 3 different techniques. RESULTS: The reliability of the classification based on spectral analysis (biparietal technique) was higher than that based on a three-degree qualitative visual reading (concordance/discordance = 58/4 versus 46/16 P < 0.01) and comparable with that of semiquantitative visual assessment based on posterior basic rhythm (concordance/discordance = 55/7 P = 0.5). The accuracy of spectral EEG analysis was higher than that of qualitative visual EEG readings alone (90 versus 75%) and comparable to semi-quantitative visual assessment (87%), however, statistical significance was not reached. In the follow-up, the variations of theta and delta relative power were found to be significantly correlated with psychometric variations. CONCLUSIONS: In conclusion, spectral EEG analysis may improve the assessment of mild hepatic encephalopathy by decreasing inter-operator variability and providing reliable parameters correlated with mental status.

ERPs obtained with the auditory oddball paradigm in coma and altered states of consciousness: clinical relationships, prognostic value, and origin of components.

OBJECTIVE: To study the event related potentials (ERPs) in coma and altered states of consciousness, their relationship with the clinical status and coma outcome. METHODS: ERPs were recorded with a passive auditory oddball paradigm in 103 patients. Their probability of occurrence and the peak latencies and amplitudes were studied as a function of the Glasgow Coma Score (GCS). Their relationship with outcome was studied in a subset of 83 patients examined within the first 4 days, and expressed in terms of sensitivity, specificity, and negative or positive prognostic values. RESULTS: When present, the ERPs to rare stimuli consisted of a fronto-central negativity (N(endog), mean latency: 330 ms) and a fronto-central positivity (P(endog), mean latency: 431 ms) following the exogenous N100-P200 complex. Both their probability of occurrence and their latencies and amplitudes were related with the GCS in anoxic and traumatic comas. The N(endog) and P(endog) had high sensitivity with a negative predictive value of 70% and 100%, respectively, but a low specificity, with a positive predictive value of 44% and 41%, respectively. CONCLUSIONS: ERPs can be recorded in some comatose patients and are likely to reflect implicit orienting processes rather than preserved consciousness. Their presence implies a good prognosis but no conclusion can be drawn from their absence.

Retrospective study of somatosensory evoked potential monitoring in deep hypothermic circulatory arrest.

BACKGROUND: We evaluated the efficiency of median-nerve somatosensory evoked potentials (SEPs) monitoring in determining the optimal level of hypothermia in 62 consecutive patients operated on under deep hypothermic circulatory arrest (CA). METHODS: CA was started at 1 degree C below the temperature at which both brainstem and cortical SEP components disappear. No additional method of cerebral protection was used. RESULTS: New neurological complications were observed in 15 patients: long-lasting in 11 and transient in 4. A retrospective analysis of SEP monitoring identified the origin of the complications in 12 cases: early CA with incomplete cooling due to emergency (3 cases); inefficient retrograde perfusion through the femoral artery during cooling due to the dissection flap effect (4 cases); embolism during rewarming (2 cases); delayed embolism (2 cases); hemorrhagic shock (1 case). In 2 cases, neurological sequelae involved the lower limbs (extracerebral origin). One case without intraoperative SEP changes was neurologically abnormal preoperatively and did not change postoperatively. There were no cases with sequelae due to excessive CA duration. CONCLUSIONS: The use of SEP monitoring to determine the optimal level of hypothermia efficiently prevents neurological sequelae of CA. It helps in monitoring the degree of cerebral protection during cooling (flap effect), and rewarming.

Brain death diagnosis in misleading conditions.

The necessity of defining brain death (BD) arose from technological development in medical science. The definition of this concept had practical consequences and opened the way to organ donation from BD patients. Nowadays, the imbalance between the number of organs available for transplantation and the size of the demand is becoming critical. In most laboratories, a BD diagnosis is made according to precise criteria and in a well-defined process. BD diagnosis should be improved, not only to assure the safety and to preserve the human dignity of the patient, but also in order to increase the rate of organ donation. By analysing some epidemiological parameters in BD diagnosis and organ donation, it appears that BD diagnoses can be made more often and more rapidly if one has a reliable, accurate, and safe confirmatory test, especially under misleading conditions (hypothermia, drugs, metabolic disturbances). In our experience, the use of multimodality evoked potentials (MEPs) to confirm a BD diagnosis has many advantages: MEPs can be rapidly performed at the patient's bedside, assess the brain stem as well as the cerebral cortex, and are innocuous for the patient. Moreover, their insensitivity to the aforementioned misleading factors is sufficient to distinguish BD from clinical and EEG states that mimic BD. They give an immediate diagnosis, and no delay is required in BD confirmation if there is sufficient cause to account for BD. MEPs are a safe, accurate, and reliable tool for confirming a BD diagnosis, and their use can improve the organ donation rate while preserving the safety of the patient.

Evoked potentials investigation of visual dysfunction after methanol poisoning.

OBJECTIVE: To present results of electrophysiologic investigations of the visual toxicity observed during the early stage of methanol poisoning. DESIGN: Retrospective, clinical study. SETTING: A 7-bed intensive care unit in a university hospital. PATIENTS: Nineteen patients admitted with a diagnosis of acute methanol poisoning. INTERVENTIONS: Visual evoked potentials were obtained within the first 48 hrs after admission; a clinical follow-up examination was performed in 11 patients, and 12 patients were followed up by visual evoked potentials beyond the same delay. Correlations between the occurrence of an optic neuropathy and clinical, biological, and electrophysiological data were studied. MEASUREMENTS AND MAIN RESULTS: A significant correlation was found between arterial pH and blood formate concentration (r2 = 0.58, p = .003), between blood formate and bicarbonate concentrations (r2 = 0.36, p = .02), and between delay from ingestion and blood formate concentration (r2 = 0.44, p = .017). Clinical outcome was correlated not only with the bicarbonate (p = .007), formate (p = .018), and methanol (p = .03) concentrations and arterial pH (p = .004) but also with a well-defined electrophysiologic pattern during the acute stage. An index of global cortical functioning > or =3 was associated with death, whereas a global cortical functioning index < or =2 was associated with survival (p = .0058). Moreover, a statistically significant difference in long-term visual impairment was found between the subgroup with abnormal wave III morphology or a global cortical functioning index of 1-2 and the subgroup with normal wave III morphology and a global cortical functioning index <1 (p = .015). Results of the electrophysiologic studies were expressed as retinal dysfunction and optic nerve injury. Five patients had normal findings on electrophysiologic examination. Ten patients had early signs of retinal dysfunction that were fully reversed in the eight patients who were followed. Ten patients had persistent electrophysiologic signs of optic neuropathy. CONCLUSIONS: Although reversible retinal dysfunction is evident in the early stage of human methanol poisoning, its absence does not preclude development of optic neuropathy. The occurrence of optic neuropathy and early electrophysiologic data are correlated.

Somatosensory evoked potential monitoring in carotid surgery. I. Relationships between qualitative SEP alterations and intraoperative events.

This paper presents the results of intraoperative median nerve SEP monitoring in 205 successive patients undergoing isolated carotid endarterectomy (CE) (N = 172) or CE followed by coronary bypass (CBP) and/or vascular replacement (VR) (N = 33). The left and right median nerves were alternately stimulated and recordings performed on 4 channels: cervical, ipsi- and contralateral parietal, and frontal. SEPs were qualitatively rated in terms of mild, moderate, or severe ipsilateral, contralateral, or bilateral abnormalities. The SEP abnormalities were subdivided into 5 categories as a function of their relationships with intraoperative events: no alterations (67.3%), early or late SEP alterations after carotid cross-clamping (15.6%), SEP alterations after a drop in blood pressure (occurring outside of or within the cross-clamping period) (15.1%), SEP alterations of a most likely embolic origin (2.4%), SEP changes after head positioning (1%), and SEP changes after a modification of the anesthetic regimen (1.5%). Only moderate to severe SEP alterations occurring soon after carotid cross-clamping justified shunt installation in 16% of the cases. SEP alterations after a drop in blood pressure were reversed merely by restoring blood pressure. The neurological outcome was uneventful in 94.2% of cases. Of the 12 patients who developed neurological sequellae, only one case presented transient sequellae after isolated CE without SEP changes while most cases either had undergone combined CE and CBP and/or VR (6 cases) or had presented SEP alterations of embolic origin (3 cases). We conclude that our system of qualitative rating of SEPs proved very sensitive to intraoperative hemodynamic disturbances or macroembolisms.

[Somatosensory evoked potentials in patients undergoing circulatory arrest under profound hypothermia]. / Le suivi par potentiels évoqués somesthésiques des patients adultes subissant un arrêt circulatoire sous hypothermie profonde.

The surgical repair of ascending aorta aneurysms can only be carried out under total circulatory arrest, and is consequently to be performed under deep hypothermia, in order to adequately decrease the metabolic requirements of the brain. However, the optimal temperature to be reached is poorly known. SEPs to median nerve stimulation were recorded in 21 operations performed in 20 patients undergoing profound hypothermia. The latencies of all SEP components increase to 21 degrees C. Waves N20 and P14 disappear at mean naso-pharyngeal temperatures of 20 degrees C and 17 degrees C, respectively, although a wide inter-individual variability was observed. We suggest to use the P14 disappearance as the criterion to perform the circulatory arrest: in fact, all surviving patients in whom this criterion was fulfilled recovered without any detectable neurological sequellae, while three patients in whom brain activities disappeared independently on body temperature presented with neurological sequellae. Moreover, particularly if patients presenting with ischemia-induced disappearance of Erb's point activities were excluded, we found a significant correlation between the duration of the circulatory arrest and the delay of N20 and P14 reappearance on rewarming. This confirms the importance of sufficient hypothermia, on the one hand; and on the other hand, our findings imply that, even if SEP monitoring considerably decreases the risk of neurological sequellae associated with these operations, the duration of the circulatory arrest should be reduced as far as possible.

The prognostic value of three-modality evoked potentials (TMEPs) in anoxic and traumatic comas.

Three-modality evoked potentials (TMEPs) were recorded in 184 comatose patients (52 anoxic, 132 traumatic). Both types of comas were associated with different TMEP patterns. Anoxic comas were associated with prognostically relevant abnormalities of cortical (visual and somatosensory) evoked potentials (EPs), while brainstem (auditory and somatosensory) EPs were not specifically altered. The prognostic value of TMEPs in anoxic comas depended on the time elapsed from the acute episode: mildly altered EPs were associated with a better prognosis in the first 10 days; strongly altered TMEPs were associated with a poorer prognosis from the first day; no definite conclusion could be drawn from mildly altered EPs after the 10th day, or from strongly altered TMEPs in the first 24 h. By contrast, both the cortical and the brain-stem activities were altered in head trauma. The abnormalities were clustered into four patterns: hemispheric damage without brain-stem involvement (pattern 1), mesencephalic lesion (pattern 2), transtentorial herniation (pattern 3), and brain death (pattern 4). Patterns 3 and 4 were uniformly associated with death. The prognostic value of pattern 1 was similar to that observed in anoxic comas. The outcome of patients presenting pattern 2 depended on the extent of hemispheric damage associated with the mesencephalic lesion; we thus suggest to systematically perform magnetic resonance imaging (MRI) in patients presenting TMEP pattern 2. We finally demonstrated that a few patients presenting absent cortical activities in the very acute stage of coma can eventually recover a good neurological function.

Rabies encephalitis mimicking the electrophysiological pattern of brain death. A case report.

A 48-year-old woman was referred from Zaire with suspected rabies encephalitis. Survival was 34 days after the onset of symptoms and the diagnosis of rabies was ultimately proven after brain autopsy. Serial neurophysiological investigations, including EEG and multimodality evoked potentials and radiological examinations (cerebral magnetic resonance imaging and computed tomodensitometry) were performed. Whereas the clinical findings and EEG were compatible with brain death at the end of the course, this diagnosis could be definitely ruled out by multimodality evoked potentials, magnetic resonance imaging and autopsy. The validity of multimodality evoked potentials is discussed in this particular setting.