Short latency facilitation between pairs of threshold magnetic stimuli studied in amyotrophic lateral sclerosis.

The aim of the present study was to investigate the effects of short latency facilitation between pairs of threshold magnetic stimuli on the motor cortex of amyotrophic lateral sclerosis (ALS) patients, at an interstimulus interval (ISI) of 1-5 ms. As compared to controls, the facilitatory effects normally recorded at ISI 1 and 3 ms were considerably reduced. This suggested that the neuronal circuitry responsible for these effects, which is supposed to be the same as those generating I-waves, is impaired in ALS.

[Spontaneous electromyographic activity. Practical importance].

Spontaneous activities are a major semeiologic sign in electromyography. The present article deals with the different aspects recorded in practice in normal and pathological cases. There are two types of spontaneous activities, those related to motor unit hyperactivity (fasciculations and myokymia) and those related to the hyperactivity of one or more muscle fibers: fibrillations, positive sharp waves, myotonic discharges and complex repetitive discharges.

Motor cortical dysfunction disclosed by single and double magnetic stimulation in patients with fibromyalgia.

Objective: To investigate the motor cortex by single and double magnetic stimulation, in patients with fibromyalgia.

Methods: Thirteen patients with fibromyalgia and 13 age-matched healthy subjects were examined. We evaluated, in both limbs, motor evoked potential (MEP) latency and amplitude and the MCA/MPA ratio, i.

[Evoked motor potentials obtained with double magnetic cortical stimulation: techniques and interpretation].

Unlabelled: The technique of motor evoked potentials (MEP) obtained with single and double magnetic stimulation of the motor cortex in man has considerably improved over the past decade. We present the techniques and parameters involved in double magnetic stimulation for clinical purposes.

Method: The conditioning-test design is used to study modifications in the amplitudes of the muscular responses to the "test" shock, recorded on the first dorsal interosseus muscle.

Double magnetic stimulation of the motor cortex in amyotrophic lateral sclerosis.

Objectives: To study the motor cortex circuitry and the motor interhemispheric influences with double magnetic stimulation in patients affected by amystrophic lateral sclerosis.

Methods: We investigated the motor cortex in 21 amyotrophic lateral sclerosis patients (ALS, 10 with bulbar and 11 with spinal onset) with double magnetic stimulation (one shock in each hand area) with 2, 4, 6, 11 and 15 ms delay between shocks and paired magnetic stimulation (both shocks in the same area), with 4, 15, 25, 35, 55, 85, 100, 155, 200 and 255 ms delays, and compared the results with those obtained in normal subjects.

Results: Double magnetic stimulation showed reduced interhemispheric facilitatory influences (maximal at 4 ms delay between shocks) when the test shock was applied on the left hemisphere in all patients; whereas no significant differences were observed compared to control (P > 0.

Somatosensory evoked potentials elicited by stimulation of lower-limb nerves in amyotrophic lateral sclerosis.

To determine lower limb somatosensory modifications in amyotrophic lateral sclerosis (ALS), we studied somatosensory evoked potentials (SEPs) elicited by stimulation of tibial posterior nerves (TP), sural nerves (SN), saphenous internous nerves (SA), and medial plantar nerves (PL) of both limbs in 24 ALS patients, and compared the results with those from 17 normal subjects. Responses were recorded according to the international 10-20 system. Normal sensory conduction velocities of SN, SA and PL and H reflexes in soleus muscles were prerequisites for patient inclusion in this study.

Interhemispheric facilitation and inhibition studied in man with double magnetic stimulation.

Double magnetic stimulation was used to investigate the influence of a conditioning magnetic shock, applied to the hand motor area, on the size of the EMG response of the first dorsal interosseous (FDI) muscle elicited by magnetic test stimulation, applied to the same area of the opposite hemisphere, in 55 subjects unaffected by neurological disease. Both hemispheres were studied and compared at different intervals between shocks, ranging from 1-15 ms. With short intervals between shocks (1-5 ms), the EMG response to the target muscle of the test shock was increased (facilitation); it diminished after 6 ms (inhibition).

Motor evoked potentials (MEPs): evaluation of the different types of responses in amyotrophic lateral sclerosis and primary lateral sclerosis.

We studied different motor evoked potential parameters: cortical threshold (CT), primary response (PR) latency and amplitude and central conduction time (CCT) at rest and after maximal voluntary contraction of the target muscles, silent period (SP) and late muscular responses (LMR) in 21 normal subjects 42- to 75-years old and compared the results to those of 17 patients with motor disease (10 amyotrophic lateral sclerosis, ALS and 7 primary lateral sclerosis (PLS). We report for the first time in patients affected by motor diseases, LMRs were similar to controls. We found abnormalities in both ALS and PLS: enhanced cortical threshold, reduced PR amplitude during maximal voluntary contraction of target muscles compared to rest and shorter SP.

[Alterations of various parameters of evoked motor potentials in amyotrophic lateral sclerosis].

To assess their interest, we studied different motor evoked potentials (MEP) parameters in 18 amyotrophic lateral sclerosis (ALS) patients and compared them to those obtained in 20 subjects unaffected by neurological diseases: cortical threshold (CT), latency and amplitude of primary responses (PR), central conduction time (CCT), silent period (SP) contralateral to the stimulated cortex and late muscular responses (LMR). In normal subjects MEP parameters were in agreement with those described in the literature, except for LMR. These were only recorded in upper limbs with latencies around 200 ms in 9 out of 20 subjects.

[Value of a rapid method to determine muscle fiber density in amyotrophic lateral sclerosis].

We shortened single fiber electromyography examination by evaluating fiber density, jitter and block numbers in the 10th and the 20th different needle positions in the extensor digitorum communis. The results obtained in 15 normal subjects and 12 amyotrophic lateral sclerosis patients were comparated. There were no significant differences with the 10th and 20th needle positions in normal subjects or in patients.

[Somatosensory evoked potentials in amyotrophic lateral sclerosis and primary lateral sclerosis].

Somatosensory evoked potentials (SEPs) were studied in 21 cases of amyotrophic lateral sclerosis (ALS) and 7 cases of primary lateral sclerosis (PLS). Despite the lack of clinical sensory abnormalities, SEPs showed abnormalities in both diseases: lack or delay of some components. In ALS these abnormalities indicate widespread sensory disturbance.

[Electromyographic, histoenzymologic and immunocytochemical aspects of affected muscles in HIV infection. Observations of five cases].

In 5 acquired-immunodeficiency syndrome (AIDS) cases without peripheral neuropathy, we observed myogen clinical signs (diffuse amyotrophy of lower limbs or cramps) or an isolated increase in seric enzyme (LDH, CK). EMG abnormalities were observed in all cases: spontaneous activities (fibrillations and positive sharp waves) in 5 cases, myogenic signs in 2 case. Muscular biopsies were normal in 3 cases and showed myopathic changes in 1 case and polymyositis in another case.

[Radicular evoked potential. Peroperative recording in lumbar disk hernias].

The evoked compound action potential of lumbar nerve roots after posterior tibial nerve stimulation at the ankle during operation were studied in 10 patients with lumbar disc herniation. The recording needle electrode was inserted into compressed the nerve root before and after excision of disc herniation. The evoked nerve root action potentials consisted of a positive-negative complex.

Normal latency values of early cortical somatosensory evoked potentials in children.

Somatosensory evoked potentials (SEPs) after median and posterior tibial nerve stimulation were studied in 172 children ranging in age from 1 day to 16 years for the purpose of obtaining normal reference values, for use in analysing pathological cases. The mean onset and peak latencies of the N wave after median nerve stimulation and of the P wave after posterior tibial nerve stimulation were calculated for 12 age groups. N and P latencies decreased from birth to 3 years of age, when they reached their minimal values.

Somatosensory evoked potentials to posterior tibial nerve stimulation in children.

The somatosensory evoked potentials (SEPs) to stimulation of the tibial nerve were studied in 88 children ranging in age from 1 day to 16 years. SEPs were not evidenced in 10 out of 44 infants less than 1 year old. In others it was a major positive wave (P) with a variable topographic distribution on the midline.

[Lumbar cord potentials evoked by stimulation of the nerves of the lower limb in man].

Lumbar cord potentials evoked by electrical stimulation of the posterior tibial and sural nerves at the ankle were recorded with monopolar epidural electrodes, at T11-T12 level in 20 subjects and were compared with surface recorded potentials. Two quadriplegic patients with spinal section were included in this group. Curare was given in two cases.

[Maturation of cerebral somatosensory evoked potentials].

Cerebral somatosensory evoked potentials (SEPs) were elicited by stimulation of the median nerve and/or posterior tibial nerve in 117 children of 1 day to 16 years old. A major negative wave (N) was consistently recorded from the parietal region of the scalp when the arm was stimulated. The peak latency, the onset latency, the rising time and the duration of H wave are closely correlated with age and body length.

[Motor nerve conduction velocity in early forms of infantile spinal amyotrophy. Diagnostic problems].

The conduction velocity of the ulnar, median and peroneal nerves was studied in 21 patients with a severe form of spinal muscular atrophy. They were slower than normal in 16 cases, particularly when the median nerve was studied. The diagnosis criteria of spinal muscular atrophy are discussed according to these data.

Myosin light chains in normal and pathological human skeletal muscles.

Thirty-nine human skeletal muscle biopsies from 24 individuals were classified as normal, neuropathic, or myopathic muscle according to classical clinical observations and histopathological properties of the muscles. The content in myosin light chains (LC) of each muscle sample was analyzed by means of a new technique of polyacrylamide gel electrophoresis that gives an improved discrimination, involving isoelectrofocusing of the muscle homogenate for the first dimension and successive migration in a urea-containing gel for the second dimension. Four different LC patterns have been observed in the normal muscles; these four patterns and three different ones have been observed in the pathological muscles.

[Evoked somatosensory cerebral potentials from the lower limb in newborn infants and infants].

In 26 babies, from 1 day to 3 months old, the somatosensory scalp potentials (SEPs) were evoked by electrical stimulation of the tibialis posterior nerve. No reproducible response in any location was obtained in 6 cases. In the other 20 cases, the initial wave was positive in 18 cases, with a peak latency at about 35 msec (P36) but the initial latency differed according to the location of the electrodes on the midline and to the baby.

[Excitability cycle of the Hoffmann reflex of the soleus in a constant pool of motoneurons. Changes in man as a function of age].

The study of the recovery cycle of the H reflex of the soleus, in constant pool, was made on 88 normal men of different ages. The recurrent inhibition has been demonstrated in most of the adults and elderly subjects. In young children, there were powerful inhibitory mechanisms, among which the Renshaw inhibition can be isolated.

[Value of preoperative investigations in the so-called "cervical myelopathy" (author's transl)].

The particular value of clinical, radiological and electromyographical features is compared in 42 patients with motor deficit related to cervicarthrosic myelopathy or amyotrophic lateral sclerosis. The initial onset of the disease was identical (motor deficit and long tracts pathways involvement). Three different groups were identifyed according to the evolution: -- Group I: (13 cases): true lateral amyotrophic sclerosis which were not operated on.