Influence of zolpidem, a novel hypnotic, on the intermediate-stage and paradoxical sleep in the rat.

Paradoxical sleep (PS) in mice, rats, and cats is preceded and sometimes followed by a short-lasting stage characterized by cortical high-amplitude spindles and hippocampal low-frequency theta rhythm. This intermediate stage (IS) seems to correspond to a transient functional disconnection of the forebrain from the brainstem. Pentobarbital and benzodiazepines greatly extend IS at the expense of PS, which is suppressed. Zolpidem, a new imidazopyridine hypnotic, was studied at 2.5, 5, and 7.5 mg/kg IP. At 2.5 mg/kg, which is already a true hypnotic dose, it only decreased PS during the first 2 h of recording with a rebound during the following 4 h of recording. At 5 mg/kg, zolpidem increased the number and total duration of IS episodes, increased IS episodes not followed by PS, and increased PS latency of occurrence. PS amount was decreased during the first three h with a rebound in the next 3 h. At 7.5 mg/kg, the total amount of PS was also decreased. The eye movement number and theta rhythm frequency of PS were unchanged. These results show that zolpidem produces less disruption of the association between IS and PS than do previous hypnotics.

[Late-onset multiple sclerosis and serum monoclonal gammopathy: an incidental association?]. / Sclérose en plaques tardive et gammapathie monoclonale sérique: association fortuite?

Four patients older than 45 years with a central nervous system demyelinating disease associated to a monoclonal gammopathy are reported. The neurologic disease met the diagnostic criteria of multiple sclerosis, with the particularity of a late onset. Monoclonal paraproteinemia was also present in the cerebrospinal fluid, associated with an intrathecal immunoglobulin synthesis. The clinical data and the course of the disease were comparable to the previous reports of late onset multiple sclerosis. A causal link between the dysglobulinemia and the neurological disease may not be demonstrated. However, such an association may underline the role of humoral processes in multiple sclerosis.

[Intradural hematoma of the foramen magnum associated with factor XIII deficiency]. / Hématome intradural du foramen magnum associé à un déficit en facteur XIII.

A 50-year-old woman, with a history of IgG monoclonal gammapathy, presented with meningitis and intradural hematoma of the foramen magnum associated with factor XIII deficiency. The patient died postoperatively of diffuse haemorrhage. Inhibitors to factor XIII are extremely rare and are congenital or acquired. Patients with factor XIII inhibitor can experience severe bleeding, and many died of cerebral haemorrhage. The role of this defect is discussed. We recommend an extensive investigation of haemostasis for patients with both episode of haemorrhagic disorder and monoclonal gammapathy.

Transcranial magnetic stimulation (TMS): compared sensitivity of different motor response parameters in ALS.

Owing to the low sensitivity of clinical signs in assessing upper motor neuron (UMN) involvement in ALS, there is a need for investigative tools capable of detecting abnormal function of the pyramidal tract. Transcranial magnetic stimulation (TMS) may contribute to the diagnosis by reflecting a UMN dysfunction that is not clinically detectable. Several parameters for the motor responses to TMS can be evaluated with different levels of significance in healthy subjects compared with ALS patients. The central motor conduction time, however, is not sensitive in detecting subclinical UMN defects in individual ALS patients. The amplitude of the motor evoked potential (MEP), expressed as the percentage of the maximum wave, also has a low sensitivity. In some cases, the corticomotor threshold is decreased early in the disease course as a result of corticomotor neuron hyperexcitability induced by glutamate. Later, the threshold increases, indicating a loss of UMN. In our experience, a decreased silent period duration appears to be the most sensitive parameter when using motor TMS in ALS. TMS is also a sensitive technique for investigating the corticobulbar tract, which is difficult to study by other methods. TMS is a widely available, painless and safe technique with a good sensitivity that can visualize both corticospinal and corticobulbar tract abnormalities. The sensitivity can be improved further by taking into account the several MEP parameters, including latency and cortical silent period decreased duration.

MRI of the intracranial corticospinal tracts in amyotrophic and primary lateral sclerosis.

Our aim was to investigate the corticospinal tracts (CST) in motor neurone disease, using MRI, and to correlate findings with clinical data. We studied 31 patients with amyotrophic (ALS) and eight with primary lateral sclerosis (PLS). The signal from the CST was classified into four grades on T2-weighted images, and compared to T2-weighted images of 37 age-matched control subjects. No abnormalities were seen in the CST on T1-weighted images and were rarely evident on proton-density weighting. Variable high signal in the CST was found on T2-weighted images in 35 patients, and in 29 control subjects. Our grades 0 and 1 were more frequent in control subjects, grades 2 and 3 more frequent in patients. We found no correlation between the high signal and clinical data, including the duration of the illness. We therefore conclude that this technique is neither sensitive nor specific except in grade 3 which is quite specific for ALS. In half the patients we found atrophy of the superior parietal gyrus, which merits further study.