[Susac syndrome in a man]. / Syndrome de Susac chez un homme.

The association of an acute encephalopathy, neurosensory hearing loss and retinal branch artery occlusions in a 35 year old man as well as the absence of systemic disease suggest the diagnosis of Susac's syndrome. This is the eighth male case described, the syndrome being more frequently reported in females.

Infrarenal aortic aneurysm and spinal cord ischaemia. A new case and review of the literature.

Surgery of the infrarenal aorta rarely gives rise to medullary lesions. This can happen however, most often after treatment of a ruptured aneurysm. We present a new case of spinal cord ischaemia following resection of an infrarenal aneurysm. Among the different factors playing a role in this fearsome and unpredictable complication, hypotension seems to be one of the most important. Different aspects of this complication are discussed in the light of our clinical case as well as a review of the literature.

Somatosensory central conduction time after sural and tibial nerve stimulation.

We recorded spinal and cortical somatosensory evoked potentials (SEPs) after sural and tibial nerve stimulation at the ankle in 34 normal subjects. Spinal SEPs were reproducible with sural nerve stimulation in only 65% of normal subjects. The spinal amplitudes were significantly smaller after sural nerve stimulation. Central conduction time (CCT) was significantly shorter when measured from onset instead of peak latencies. There was a significant difference between CCT with tibial nerve and sural nerve stimulation. Our results are consistent with the idea that CCT measures from onset and peak latencies do reflect the travel of the afferent volley in different spinal fiber populations.

Dissociation of P13-P14 far-field potentials: clinical and MRI correlation.

P13 and P14 far-field potentials are recorded over the scalp with median nerve stimulation when non-cephalic reference is used to measure somatosensory evoked potentials. The dissociation of these 2 potentials is exceptional. Only 2 cases subsequent to pontine lesions have been described hitherto. We report the case of a 31-year-old woman with a low grade glioma located at the spino-medullary junction who presented a P13-P14 far-field dissociation. This case fully supports the independent nature of the P13 and P14 potential generators.

[Course of central somatosensory conduction in a case of vitamin B12 deficiency]. / Etude évolutive de la conduction somesthésique centrale dans un cas d'avitaminose B12.

We report clinical and neurophysiological data of a 58 year-old man with vitamin B12 deficiency and a 6 years follow-up. The initial clinical disorders did not permit a clear distinction between peripheral and central nervous system disease. Detailed analysis of the somatosensory central conduction time (measured from onset latencies of N11 and N20) showed clear evidence of slowed down conduction at spinal cervical level (reflected by the N11-P14 interval) whereas supraspinal conduction (as shown by the P14-N20 interval) was normal. The patient's condition improved under treatment, and the somatosensory central conduction time was progressively shortened. After 6 years of treatment, the neurological examination and the somatosensory central conduction interval were normal. However, analysis of the spinal conduction still showed slowed down conduction.

The effect of stimulus frequency on post- and pre-central short-latency somatosensory evoked potentials (SEPs).

We assessed the influence of the stimulus frequency on short-latency SEPs recorded over the parietal and frontal scalp of 26 subjects to median nerve stimulation and 16 subjects to digital nerve stimulation. When the stimulus frequency is increased from 1.6 Hz to 5.7 Hz, the amplitude of the N13 potential decreases whereas the P14 remains stable. The amplitude of the N20 is not changed significantly whereas the P22, the P27 and the N30 decrease significantly. In 50% of the subjects 2 components can be seen within the frontal negativity that follows the P22: an early 'N24' component, which is not affected by the stimulus rate, and the later N30, which is highly sensitive to the stimulus frequency. The distinct amplitude changes of the N20 and P22 with increasing stimulus frequency is one among other arguments to show that these potentials arise from separate generators.

The somatosensory central conduction time: physiological considerations and normative data.

The somatosensory central conduction time (CCT) can be measured from the peak of N13 to the peak of N20 (peak CCT) or from the onset of N11 to the onset of N20 (onset CCT). The onset and peak CCT were measured concomitantly in 40 normal subjects and the mean peak CCT was significantly shorter than the mean onset CCT. Records with different reference electrodes (linked earlobes, F3, over the ipsilateral parietal scalp, non-cephalic reference in some subjects) showed no significant latency change of the N11 onset, the N20 onset, the peak and onset CCT in contrast with the significant latency changes of the N13 and N20 peak with different montages. The onset CCT was divided by the onset of the P14 far-field in 2 parameters, the N11-P14 interval predominantly concerned with spinal conduction and the P14-N20 interval which reflected only supraspinal conduction. The onset and peak CCT, the N11-P14 and P14-N20 intervals were not correlated with height or age. Three independent recording sessions over 1 year in 16 subjects showed that the parameters were reproducible. From the physiological point of view the onset and peak CCT are different parameters and the anatomical correlates of both parameters are discussed.

[Endocrinological and neurophysiological modifications in a case of atropinic delusional state]. / Modifications endocriniennes et neurophysiologiques dans un cas de délire atropinique.

In this case report, we observed a delirium probably owing to toxic effects of homatropine eye drops. We reproduced this syndrome and we reversed it with physostigmine salicylate as an antidote. We observed a decrease of cortisol at 9.00 a.m. and impairment of regional cerebral blood flow with increase in the previous right side. The unusual susceptibility of this patient to the anticholinergic effect of homatropine is perhaps related to a preexisting mild cognitive defect possibly related to a cholinergic neurotransmitter deficit.

Repeated delirium from homatropine eye-drops. A case report.

The administration of homatropine eye-drops precipitated several episodes of delirium in a 69-year-old woman. The unusual susceptibility of this patient to the central anticholinergic effect of homatropine is perhaps related to a preexisting mild cognitive defect possibly related to a cholinergic neurotransmitter deficit.