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Vagus Nerve Stimulation (VNS) is recognized as an efficient procedure for controlling seizures in patients with drug-refractory epilepsies. It is used as a palliative procedure as a complement to conventional treatment by antiepileptic (AE) drugs and, according to literature, 40 to 50p.cent of patients report a decrease in seizures frequency >or=50p.cent, which is usually accepted to classify patients as responders in add on AE drug trials. The objectives of this study based on retrospective analysis of 50 consecutive patients with partial (39) or generalized (11) refractory epilepsy non eligible for surgery were; firstly to evaluate the global long term VNS efficacy and secondly to identify potential predictors of the VNS effects on seizure frequency. No patient has been seizure free at any moment of the follow up (2.8+/-1.8 years, max: 6 years) and the AE has been maintained in all. During follow up 44, 66, 61 and 58p.cent of patients were classified as responders at 6 months, 1, 2 and 3 years, respectively. Logistic regression analysis showed that: the percentage of responders at 6 months of follow up and later was significantly higher than that before 6 months (p=0.002); generalized epilepsy was predictive of a better outcome as compared to partial epilepsy (p=0.03); there was a trend for a better outcome in partial epilepsies symptomatic of a focal lesion than in those with normal brain MRI (p=0.06). These results are in line with previously published data in terms of global efficiency and confirm that seizures control does not reach its maximal level before at least one year of VNS. In severe generalized epilepsies (either secondary or cryptogenic) manifesting by frequent falls due to atonic or tonic-clonic generalized seizures VNS is a useful palliative procedure, which entails much les of surgical risk than callosotomy. The better VNS effects in patients with partial epilepsy possibly reflect the high incidence in our series of Malformations of Cortical Development, which have been identified as one the few variables possibly predictive of a response over 50p.cent of seizures frequency reduction.

We have made a review on the use of evoked potentials in multiple sclerosis (MS) for the past 30 years, in the diagnosis of MS, to disclose subclinical lesions or to assess atypical symptoms. Yet the role of evoked potentials in evaluation of multiple sclerosis has been changed since MRI is now widely and easily used for the diagnosis of MS. Evoked potentials are useful when symptoms are atypical without any objective impairment and when symptoms have already recovered at the time of clinical examination. Visual evoked potentials and somatosensory evoked potentials are widely used thanks to their diagnostic value and their ability to disclose spatial dissemination of multiple sclerosis. Evoked potentials have to be recorded in validated technical conditions such as to ensure reliability of data and have to be interpreted in reference to a population of healthy people recorded in the same conditions and in the same age range as MS patients.

A 78-year-old right handed man with a past history of atrial fibrillation developed in November 1994, a slight right hemiparesis with aphasia which cleared over one month. Head CT scan showed a left middle cerebral artery infarct involving the posterior part of the temporal lobe. In September 1995, a second stroke occurred. Head CT scan revealed a recent right middle cerebral artery infarct within the posterior part of temporal cortex. Auditory agnosia was diagnosed. Auditory evoked potentials recording showed bilateral dysfunction of central auditory pathways mainly over the right hemisphere. Clinical data and evoked potentials suggest that auditory agnosia might be related to the right temporal lobe damage. This later is involved in linguistic processes as suggested by positron emission tomography studies.

In this retrospective study we report our 12 years' experience of the Wada test (intra-carotid injection of short half-life barbiturates) using Methohexital. The clinical manifestations induced by Methohexital were similar to those observed with Amobarbital. The inocuity of the test is attested by the finding that no incident or accident has been reported in 126 injections, the risk being the same as for arteriography. The two main advantages of Methohexital over Amobarbital are: 1) short hemispheric narcosis, which makes it possible to explore the two carotid arteries territories during the same session and limits the risk of drug diffusion to the two hemispheres; 2) the rare occurrence of vigilance troubles such as drowsiness or falling-asleep, which are frequently observed during Amytal Wada test. Intracarotid Methohexital injections are effective to determine the hemispheric lateralization of language and useful to evaluate the role of each hemisphere in memory, especially before the surgical treatment of drug-resistant focal epilepsies.

One hundred epileptic patients were included in this study according to the following criteria: intractable partial epilepsy, normal CT scan and focal EEG abnormalities. Eighty-nine patients were suffering from complex partial seizures of temporal or frontal origin, 55 and 34 cases respectively. Eleven patients presented with only simple partial seizures. MRI was abnormal in 31 patients. The abnormalities were: focal T2 increased signal intensity (13 cases) most often temporal (10 cases), cryptic arteriovenous malformation (4 cases), focal T1 and T2 signal abnormality (4 cases), focal atrophy (2 cases) and multiple abnormal T2 signals scattered in the white matter (8 cases). The site of MRI abnormalities was consistent with electroclinical data in 22 patients, of whom 20 had a temporal lobe epilepsy. Thus MRI proved to be more often abnormal in temporal than in frontal lobe epilepsy (36 p. 100 and 5.9 p. 100 respectively) when the CT scan is normal. However MRI data, particularly focal T2 hypersignals should be confronted to electroclinical and metabolic findings whenever functional surgery is considered.

Visual (VEP), brainstem auditory (BAEP) and somatosensory (SEP) evoked potentials were recorded over a 6 year period in 917 patients with or suspected of multiple sclerosis according to Mc Alpine's criteria. Evoked potentials provided information of diagnostic relevance in detecting clinically unsuspected lesions (spatial dissemination). They also gave valuable informations in patients with atypical or borderline clinical features. When abnormal, VEP indicated clinically silent lesions in 45.1 p. 100 of patients with definite MS, 66 p. 100 of those with probable MS and 78 p. 100 of the possible MS. Less than 15 p. 100 of SEP and/or BAEP abnormalities were found in 83 patients with a simple or recurring retrobulbar optic neuritis. Thirteen patients with acute transverse myelopathy and no prior history of neurological disease were studied. All had normal visual and brainstem auditory evoked potentials. Abnormal VEPs helped to the clinical assessment of 88 patients with progressive spastic paraparesis 46,6 p. 100 of whom had abnormal VEPs demonstrating disseminated lesions and 36,1 p. 100 had abnormal BAEPs. The frequency of the various types of VEP, BAEP and SEP abnormalities was studied as well as their course on repeated recordings. Results of multivariate analysis are given. It was found that the longer the time interval between the first MS relapse and the evoked potential recording, the higher the incidence of abnormalities. The incidence of evoked potentials abnormalities was lower in patients with normal CSF and higher in patients with inflammatory CSF. The abnormalities were more frequent when patients had clinical evidence of lesions of the sensory pathways explored by the tests.

The authors describe the results of treatment of four cases of spasmodic paraplegia from Paget's disease of the vertebrae with diphosphonates (EHDP and CL2 MDP). The quality and long duration of the functional results obtained by this new treatment of Paget's disease indicate that medical treatment is essential for the medullary complications of this affection.

The volume-conducted responses of the lemniscal pathways to median nerve stimulation at wrist may be recorded on the scalp (far-field potentials). These positive far-field SEPs components are widely distributed on the scalp and their peaking latencies vary between 9 and 15 milliseconds. In normal adults a maximum of 4 far-field potentials (P9, P11, P13 and P14) may be individualized; two of them (P9 and P14) are constant. These SEPs were studied in two patients with lateralized somatosensory loss; one with a cervico-medullary traumatic lesion, the other with a thalamic infarct. These observations allow the following conclusions 1) the P9 component takes origin in the proximal part of the brachial plexus roots; 2) the P14 potential has a brainstem origin; 3) the contralateral N20 potential is generated in (or close to) the primary somato-sensory cortex (SI). Thus it is possible with a single channel to record the activity of the somatosensory pathways from dorsal roots up the parietal cortex.

A case of chronic disabling sensory-motor polyradiculitis occurring in a female patient and followed up for 18 months is reported. Clinical findings were papilledema, hypertrichosis, abnormal pigmentation of the skin, generalized edema, and spontaneous cutaneous necrosis. The diagnosis of a plasmocytic dyscrasia to IgA Lambda was made at a late stage of the disease. There were no signs of a solitary plasmocytoma or of diffuse myeloma. At autopsy, there were mild lesions in the peripheral nervous system, but no plasmocytic infiltration or amylosis was seen on optical or electron microscopy. This case is similar to other clinical cases reported mainly by Japanese authors.

The present work is an evaluation of brainstem auditory evoked potentials (BAEP) as a tool for neurological diagnosis. Filtered alternate clicks with monaural stimulation and ipsilateral recording between the vertex and the ipsilateral mastoid have been used. Normative data of the laboratory established in 50 normal subjects, mean age 35 years, and criteria for interpretation are given. 155 patients had or were suspected of having multiple sclerosis. In definite multiple sclerosis (33 patients), BAEP were abnormal in 67 p. 100 of the cases, among them the 4 patients with an internuclear ophtalmoplegia. In probable multiple sclerosis (54 patients) BAEP were abnormal in 41 p. 100 of the cases and in possible multiple sclerosis (68 patients) there were 19 p. 100 with abnormalities. Results show that BAEP are clearly a useful tool for diagnosis in progressive paraplegia, in optic neuritis, and in cases in which symptoms and signs lead to discuss posterior fossa tumours. In 66 patients with suspected or proved tumours (acoustic neurinomas excluded) and in 25 patients with vascular disease, the contribution of BAEP to neurological diagnosis is of unequal interest. In some cases BAEP only confirmed the data of the clinical examination. When tumours were diagnosed with the CT scan, BAEP could help in pointing out the accurate relation of the tumour with the brainstem and the auditory pathways. In 36 patients the contribution of BAEP was important in establishing the rostral extension of bulbocervical tumours or, mainly, in indicating the presence or absence of infiltrating brainstem tumours which were not clearly apparent on the CT scan.