[Motor evoked potentials. Technic and results in the normal subject]. / Potentiels évoqués moteurs. Technique, résultats chez le sujet normal.

The transcranial stimulation of the motor cortex and spinal cord was introduced in clinical neurology by Merton and Morton (1980). This reproducible and non invasive technique gives the possibility to elicit unilaterally or bilaterally evoked motor potentials. It is possible to define a Total Conduction Time (TCT) from cortex to muscle and a Peripheral Conduction Time (PCT) from spinal cord to muscle. The central conduction time is given by the latency difference between TCT and PCT. This delay represents the duration of the descending corticospinal volley plus the delay necessary to depolarize spinal motor neurons. For central pathways supplying the upper limbs TCT is 4.3 milliseconds and for central pathways supplying the lower limbs TCT is 9.3 milliseconds. This technique of central motorpathway assessment can be used to define the magnitude of a central motor deficit in neurological diseases affecting the corticospinal tract, during surgical procedures involving the spinal cord and in comatose patients. The new magnetic stimulation is painless and will probably widen the utilization of this method.

Central motor conduction in motor neuron disease.

Central motor conduction was assessed in 13 patients with motor neuron disease and in 15 control subjects. All patients with motor neuron disease, even those without clinical pyramidal signs, had slowed central motor conduction, and in some the delays were asymmetrical. Evoked motor potentials represent a new and reliable method to detect physiological abnormalities of central motor pathways early in the course of motor neuron disease.

Tick-bite meningoradiculoneuritis: clinical, electrophysiologic, and histologic findings in 10 cases.

We studied 10 adults with meningoradiculitis several weeks after a tick bite (Ixodes). EMG evidence of denervation was associated with normal motor conduction velocities, prolongation of distal latencies, and low sensory amplitudes, suggesting axonal neuropathy. Sural nerve biopsies confirmed the axonal involvement. Infiltrations of lymphocytes and plasma cells, sometimes forming thick pericapillary cuffs with no accompanying necrosis of vessel walls, were numerous. Many capillaries of the endoneurium, perineurium, and epineurium were affected in this way.

Tick bite meningoradiculitis. Ten cases.

A study was undertaken on 10 cases of meningoradiculitis following a tick bite. All patients developed neurologic manifestations and C.S.F. abnormalities. Electrophysiologic studies demonstrated decreased motor potential amplitude and normal motor conduction velocity suggesting distal axonal involvement. Radicular lesions were suspected due to the presence of delayed F waves. This is the first study to confirm these electrical findings by histologic examination of the superficial peroneal nerve of the leg during the course of thick meningoradiculitis.

[Neuropathies of unknown etiology. A study of 48 cases]. / Les neuropathies de cause indéterminée. Etude de 48 cas.

A prospective study, carried out over 7 years, showed that out of 432 peripheral neuropathies followed up for 12 months, no cause could be discovered in 48 (11%). This is discussed with respect to the previous few reports. In fact none of these studies is strictly comparable. In spite of complementary investigations and observation of the course of the disease, it may be difficult to be sure to which etiology any individual case belongs; e.g. genetically determined neuropathies, chronic inflammatory polyradiculoneuritis or drug-induced neuropathies. However, it is clear that the group of neuropathies of undetermined origin, is clinically, pathologically and developmentally heterogeneous. This suggests that these patients should be classified as having a yet undetermined disease process. In our series, long term follow up enabled us finally to find a cause in a significant number of cases.

Acute pure sensory paraneoplastic neuropathy with perivascular endoneurial inflammation: ultrastructural study of capillary walls.

We studied a patient with epidermoid carcinoma of the lung (treated surgically 1 year earlier) and an acute symmetric pure sensory neuropathy that regressed almost completely within 1 month. Superficial peroneal nerve biopsy 15 days after onset showed evidence of demyelination with perivascular endoneurial inflammation. On ultrastructural examination, lymphocytes were seen passing through endothelial cells of endoneurial capillaries.

Early vesico-ureteral reflux following conus medullaris injury: case report.

The authors describe severe vesico-ureteral reflux and simultaneous renal insufficiency which occurred after a spinal cord injury to the conus medullaris. They point out the misleading character of these injuries when there are only minimal neurological signs in the trunk and limbs. The main clinical consequence may be an isolated neuropathic bladder which, if not detected, delays treatment. Additionally, they underline the role of mixed bladder and sphincter lesions in the development of renal insufficiency; also the role of increased intravesical pressure during filling and emptying with bilateral vesico-ureteral reflux.

Amyotrophic lateral sclerosis in Limousin (Limoges area, France).

Several epidemiological studies of amyotrophic lateral sclerosis have suggested that this neurological disease is uniformly distributed throughout the world. We report here the only study providing data on the incidence of this disease in France. It is based on a retrospective study of the Limoges region (Limousin) which contains only one university department of neurology. The study, conducted from February 1, 1977, to February 1, 1985, was not limited to in- and out-patients seen at this department, as we also contacted other non-hospital doctors who might have examined such patients. The average normal incidence was found to be 0.91 per 100,000 population. The male:female ratio was 1.16:1, and the median age of onset was 65 years. Median survival was 20.7 months.