Guy Farnarier

Different susceptibilities of the geniculate and extrageniculate visual pathways to human Creutzfeldt-Jakob disease (a combined neurophysiological-neuropathological study)

Flash evoked visual potentials (FEPs) of 7 patients with advanced Creutzfeldt-Jakob disease (CJD) were compared with those recorded in 7 patients with senile dementia of the Alzheimer type (SDAT), in 13 age- and sex-matched healthy volunteers and in 7 neuropsychiatrically normal subjects whose occipital evoked responses were increased in amplitude (amplitude controls). Post-mortem examination was performed in 4 of 7 CJD patients in order to map pathological changes along the visual pathways, including the retino-geniculo-striate and extrageniculate pathways. Normal FEPs were typified by 2 constant early components (P1 and N2) followed by several (3 or more) late components that were characterized by marked interindividual variability. Amplitude controls had enlarged (from 14 to 44.8 microV, mean 25.7) P1 component. Both SDAT and CJD patients had normal early FEP waves (P1 and N2) and important alterations of the late FEP components. Moreover, a late positive component was responsible for abnormally enlarged FEPs (52.6 and 58.2 microV) in 2 CJD patients. Finally, electroretinograms, recorded in 1 CJD patient, were normal. These findings suggested relative functional integrity of the retino-geniculo-striate pathway associated with important dysfunction of the cortical visual processing in both SDAT and CJD patients. Pathological studies disclosed preservation of optic nerves, chiasmas, lateral geniculate nuclei and Gennaris strip of the striate cortex but associated with important spongiform change, neuronal loss and gliosis in the superior colliculi (layer II), pulvinar, extrastriate cortex and layers II-III, V and VI of the striate cortex. We conclude that different visual pathways have different susceptibilities to CJD: important functional and anatomical alterations of the intracortical and extrageniculate pathways contrast with relative preservation of the retino-geniculo-striate pathway.

Sleep Electroencephalogram at the Early Stage of Creutzfeldt-Jakob Disease

We describe sleep EEG studies in three patients at the early stage of Creutzfeldt-Jakob disease. Little work has been devoted to the study of the sleep EEG in the course of the CJ disease: disorganized sleep architecture was noted, associated with a decrease in stage 4 and an almost complete disappearance of the REM stage. Our patients were considered to have normal stage 2; yet spindles and K complexes were rare at this stage. No evolution towards stage 4 was noted. The percentage of rapid eye movement sleep was significantly low in two cases and normal in one case. Sleep disturbances in the other dementing disorders are reported.

Rating scale for psychogenic nonepileptic seizures: Scale development and clinimetric testing

Our aim was to develop a clinimetric scale evaluating motor phenomena, associated features, and severity of psychogenic nonepileptic seizures (PNES). Sixty video/EEG-recorded PNES induced by suggestion maneuvers were evaluated. We examined the relationship between results from this scale and results from the Clinical Global Impression (CGI) scale to validate this technique. Interrater reliabilities of the PNES scale for three raters were analyzed using the AC1 statistic, Kendalls coefficient of concordance (KCC), and intraclass correlation coefficients (ICCs). The relationship between the CGI and PNES scales was evaluated with Spearman correlations. The AC1 statistic demonstrated good interrater reliability for each phenomenon analyzed (tremor/oscillation, tonic; clonic/jerking, hypermotor/agitation, atonic/akinetic, automatisms, associated features). KCC and the ICC showed moderate interrater agreement for phenomenology, associated phenomena, and total PNES scores. Spearmans correlation of mean CGI score with mean total PNES score was 0.69 (P<0.001). The scale described here accurately evaluates the phenomenology of PNES and could be used to assess and compare subgroups of patients with PNES.

Sensory evoked potentials in Creutzfeldt-Jakob disease.

Eight patients presenting with intermediate or terminal evolution of Creutzfeldt-Jakob disease (CJD) were investigated by means of evoked potentials. Fifteen age-matched healthy subjects served as controls. The 8 patients had well-recognizable but simplified flash evoked potentials (FEPs) consisting of P1 and N2 waves followed by a single late positive (P2) deflection. Enlarged FEPs were found in 2 of the 8 patients. The somatosensory central conduction time was normal in 3 of 5 patients, and it resulted in upper normal limits or was moderately slowed in 2 patients. No enlarged somatosensory scalp potentials were recorded. Cortical somatosensory responses were characterized by an unrecognizable (4 patients) or delayed (2 patients) N33 wave. Brainstem auditory evoked responses, recorded in 6 patients, were normal. In CJD very important functional impairment of the sensory cortical areas is associated with absent or mild dysfunction of the subcortical sensory pathways.

Disappearance of periodic sharp wave complexes in Creutzfeldt-Jakob disease.

Periodic sharp wave complexes (PSWC) are sensitive and specific of Creutzfeldt-Jakob disease (CJD). Once they have emerged, PSWC may exceptionally disappear in the terminal stage of the disease, as a consequence of the flattening of scalp electroencephalogram (EEG). We document the disappearance of PSWC in serial EEG during the clinical course in two women (57 and 70 years of age) with pathologically proven CJD. Despite PSWC disappearance, diffuse theta-delta activity was still well recognizable. Moreover, external stimuli failed to trigger PSWC. The absence of PSWC in CJD might be due to the timing and frequency of EEG recordings. PSWC disappearance should not be interpretated as evidence against the diagnosis of CJD.

Etat confusionnel critique prolonge a point de depart frontal chez un sujet age

Summary The authors discuss the case of a man who, at the age of 63, presented episodes of prolonged confusional state de novo. The EEG recordings showed the existence of an electrical status with widespread spikes and polyspike-and-waves of the “absence status.” Further recordings showed a focal onset of one of the episodes of prolonged confusional state. The electric and clinical characteristics of this observation indicate that a frontal localisation with secondary generalization of the discharge is probable. This electro-clinical picture is compared to other literature on the subject and its nosological specificity is discussed.

Electroencephalographic and anatomo-clinical evidences of posterior cerebral damage in hypertensive encephalopathy

The authors describe two patients suffering from hypertensive encephalopathy associated with epileptic seizures and anatomo-clinical evidences of posterior cerebral damage. The concordant electroencephalographic features with clinical signs and anatomic lesions of these two patients are discussed, in order to make some considerations about the role played by the blood-brain-barrier damage on the physiopathology of the hypertensive encephalopathy.

Potentiels évoqués somesthésiques et myoclonus d'action

Summary The authors studied the somatosensory evoked potentials (SEPs) in 16 cases of myoclonic encephalopathies: 8 cases of dyssynergia cerebellaris myoclonica (DCM); 2 cases of dyssynergia cerebellaris progressiva (DCP); 2 cases of Laforas disease; 1 case of ceroid lipofuscinosis; 3 unclassifiable myoclonic syndromes. The mean age of the patients was 18 years and the mean duration of pre-study evolution was 10 years. All the patients had been treated by anticonvulsant drugs (phenobarbital, valproic acid, benzodiazepines). The amplitude of the complex P1N2 at the level of the contralateral parietal cortex, with stimulation of the median nerve at the wrist, was found to be enlarged in only 6 cases and giant responses (over 40 μV) were obtained in 2 cases. Only half of the patients with DCM presented a high amplitude response. There was no correlation either with clinical parameters (and in particular, certain patients with marked action myoclonic jerks have a normal SEP), or with the EEG data: on the contrary, the amplitude variations of the SEPs are most often similar to variations of the visual evoked potentials.

Le vomissement: un symptome critique epileptique

Summary The authors present 3 cases of ictal vomiting with 2 seizures recorded on the EEG. The critical vomiting is always sudden, projectile, and lasts a short period. The interictal and ictal EEG recording showed a focus or a seizure involving the frontal temporal regions. The seizures were kept under control by a therapy with carbamazepine. Vomiting can be a particular semiological aspect of a possible seizure as are other vegetative features. The authors stress this critical aspect on one hand differentiating it from non-epileptical ictal phenomena (in particular childrens cyclic vomiting), on the other hand from post-ictal vegetative phenomena of a major or partial seizure.

Etat d'absence a predominance EEG unilaterale (a propos d'une observation privilegiee)

Summary The authors describe a 33-year-old woman who, from the age of 15 years, presented many generalized epileptic seizures per year starting with right-sided adversion or gyration, several times per month long absences and occasional absence status lasting up to 3 days. In this patient, the hyperpnoea provoked a clinically typical absence status with 3 c/sec rhythmic continuous spike-and-wave discharges which were more evident on the left frontal regions of the scalp. This electro-clinical picture is compared to similar cases described in the literature and its nosological specificity is discussed.