Human handedness and asymmetry of the motor cortical silent period.

We performed transcranial magnetic stimulation of the motor cortex in 22 left-handed and 25 right-handed subjects during active contraction of a small hand muscle. Motor evoked potentials had the same latency, amplitude and threshold on both sides of the body, whilst the silent period duration was shorter in the dominant hand. Silent periods elicited by nerve and brainstem stimulation were the same in both hands. Since the latter part of the cortical silent period is due mainly to withdrawal of corticospinal input to spinal motoneurones, we speculate that the results are compatible with the suggestion that tonic contractions of the non-dominant hand are associated with a greater involvement of the corticospinal tract than those of the dominant hand. It also seems likely that there is an asymmetry in the excitability of cortical inhibitory mechanisms with those responsible for the cortical silent period being less excitable in the dominant motor cortex.

Platelet activating factor is elevated in cerebral spinal fluid and plasma of patients with relapsing-remitting multiple sclerosis.

Platelet-activating factor (PAF) is a phospholipid mediator of inflammation with a wide range of biological activities, including the alteration of barrier function of endothelium. A biological assay combined with high pressure liquid chromatography-tandem mass spectrometry showed that plasma and cerebral spinal fluid (CSF) PAF levels in 20 patients with relapsing/remitting or secondary progressive multiple sclerosis (MS) studied by magnetic resonance imaging (MRI) were significantly higher than in healthy controls (plasma: 3.29+/-4.52 vs. 0.48+/-0.36 ng/ml, p < 0.002; CSF: 4.95+/-6.22 ng/ml vs. 0.01+/-0.04 ng/ml, p < 0.0001). Values were also significantly higher in relapsing/remitting than in secondary progressive (plasma: 5.10+/-4.97 vs. 0.52+/-0.85 ng/ml, p < 0.005; CSF: 8.59+/-6.39 vs. 0.55+/-0.68 ng/ml, p < 0.002). It was also found that both plasma (R2: 0.65) and CSF (R2:0.72) levels were correlated with the MRI number of gadolinium enhancing lesions, which are markers of blood-brain barrier (BBB) injury, whereas their peaks were not correlated with the MRI number of white matter lesions, nor with the expanded disability status score (EDSS) according to Kurtze [Kurtze, J.F., 1983. Rating neurological impairment in multiple sclerosis: an expanded disability scale (EDSS). Neurology 33, 1444-1452]. Both plasma and CSF in patients with relapsing/remitting MS and marked gadolinium enhancement contained the two major molecular species of PAF: 1-0-hexadecyl- (C16:O) and 1-0-octadecyl-sn-glycero-3-phosphocholine (C18:O). The ratio of the two molecular species was different in the two biological fluids, being PAF C18:0 more abundant in CSF and PAF C16:0 in plasma, indicating a different cellular origin of PAF or different enzymatic processing. These findings suggest that PAF is a significant mediator of BBB injury in the early stages of MS, rather than a marker of its progression and severity.

Interleukin-2 receptor expression on blood monocytes of patients with multiple sclerosis.

We studied the expression of class II MHC product (HLA DR) and IL-2 receptor on circulating monocytes (M phi) in MS patients, neurological and healthy controls, by double color flow cytometry. In all groups most M phi were DR+ without significant differences. More interesting, low percentages of IL-2+ M phi were detectable in healthy and neurological controls, whilst a few MS patients with active disease showed higher levels. This finding is in agreement with similar studies in other T-cell mediated diseases and with the report of rare IL-2+ macrophages in MS plaques. Although the actual role of IL-2+ M phi in the immune response still needs elucidation, our findings suggest their relevance to the pathological process of demyelinating disease.

Perineal motor potentials to magnetic stimulation, pudendal evoked potentials and perineal reflex in women.

Motor potentials to transcranial and lumbar magnetic stimulation were recorded from the perineum in 14 healthy women. The response to transcranial stimulation presented an onset at 20.2 +/- 1.3 ms and a negative peak at 25.1 +/- 1.9 ms. Lumbar responses presented an onset at 5.1 +/- 0.8 ms, and the motor central conduction time measured 14.4 +/- 1.5 ms. Perineal reflex, cortical and lumbar pudendal evoked potentials were recorded after electrical stimulation of the labia minora. These tests are of possible clinical use in the evaluation of sphincter disturbances as they investigate the afferent and efferent pathways concerning pudendal nerve function.

Motor potentials of inferior orbicularis oculi muscle to transcranial magnetic stimulation. Comparison with responses to electrical peripheral stimulation of facial nerve.

Magnetic stimulation at the vertex evoked a motor potential (MP) in the inferior orbicularis oculi muscle of 10 healthy subjects with an onset latency of 8-13 msec. Its amplitude increased and its latency decreased when the muscle was contracted: the latency measured 9.5 +/- 1.3 msec with an intensity of stimulation 10-15% above threshold in the contracted muscle. This MP is secondary to excitation of the motor cortex. With the coil placed over the occipital scalp and the same stimulation intensity, an MP was recorded with an onset latency at 4.5 +/- 0.6 msec. This response reflects the activation of the facial nerve root. The peripheral electrical stimulation of the facial nerve at the mandible angle elicited an MP with an onset latency at 3.5 +/- 0.4 msec. Most records showed the presence of late components at about 30 msec for all types of stimulation.

Study of central and peripheral motor conduction in normal subjects.

Motor potentials to transcranial and cervical magnetic stimulation and F-wave were recorded in 37 arms of 25 normal subjects. Clockwise and anticlockwise cervical stimulation were performed over C5, C7 and T2 spinous processes. A significant correlation was found between height and measurements of central and peripheral motor conduction. Peripheral motor conduction measured by F-wave derived techniques (Kimura formula) was 0.5 msec higher as compared with responses to cervical magnetic stimulation. The site and current flow direction of cervical magnetic stimulation influenced the amplitude of responses but not their latency: responses were larger in the right arm when the centre of the coil was placed over the C5 spinous process and clockwise stimuli were used. The same results were obtained in the left arm when the coil was reversed.

Motor potentials of bulbocavernosus muscle after transcranial and lumbar magnetic stimulation: comparative study with bulbocavernosus reflex and pudendal evoked potentials.

Motor potentials of the bulbocavernosus muscle were recorded in 17 healthy subjects after transcranial and lumbar magnetic stimulation. The latencies (SD) were respectively: 22.9 (1.8) and 5.9 (0.4) ms. The central conduction time was 17.0 (2.5) ms. The bulbocavernosus reflex presented an onset at 34.5 (3.3) ms and a negative peak at 43.1 (3.9) ms. The cortical pudendal evoked potential was W shaped: the first peak had a latency of 35.4 (2.8) ms. The concurrent recording of motor potentials, bulbocavernosus reflex, pudendal evoked potentials gives a measure of peripheral and central, afferent and efferent neurological pathways related to pudendal nerve function.

Pontomedullary encephalitis and basal meningitis due to Listeria monocytogenes: report of a case.

A case of CNS listeriosis in a 49-year-old man, previously in good health, is described. The illness showed a biphasic clinical pattern with a prodromal phase characterized by headache, fever and leukocytosis and subsequent development of pontomedullary cranial nerve paresis. The infection was rapidly progressive and fatal. Gram-positive rods, identified as Listeria monocytogenes, were detected in CSF samples only at the end stage of illness. Neuropathological abnormalities consisted of rhombencephalitis and basal meningitis. The major difficulties encountered in the early diagnosis of CNS listeriosis are discussed.

Ataxic hemiparesis: further CT confirmation of an old localizing hypothesis.

4 cases of ataxic hemiparesis syndrome are supported by CT proof of a lesion confined to the posterior and superior part of the internal capsule, near the corona radiata. The site of lesion is usually held to be the basis pontis and rostral midbrain. We intend to furnish further evidence in support of an old hypothesis incriminating the corona radiata-internal capsule.

[On a muscular dystony case from manganism. Therapeutic clinic considerations (author's transl)]. / Su di un caso di distonia muscolre da manganismo. (Considerazioni clinico-terapeutiche).

It is described a muscular dystony case of manganism, treated with good results in two following phases with haloperidol and diazepam and then with L-Dopa + benserazide. On the basis of clinical and laboratory results, it makes way the hypothese that the haloperidol had developed his therapeutic action with chelation mechanism.