Knee extensor torque and EMG in standing and sitting positions

s39 muscles (thenar, EDC and biceps) and the tibialis anterior muscle. We studied 25 elderly subjects ( > 70 years) and 122 patients (mean age 51.7 years), having the following degenerative neurological diseases: ALS, N = 55; Huntington’s disease, N = 9; Parkinson’s disease, N = 26; Guamanian ALS-PD, N = 22; and Alzheimer’s disease N = 10. In healthy elderly subjects, the MEP latency and central motor delay was modestly but not significantly prolonged. However, compared to a younger control group (N = 75) with a mean age of 49.7 years, the MEP amplitude, expressed as MEP/max Mwave X 100, was significantly reduced. For example, in the younger subjects, the thenar MEP amplitude measured 56.1+ 23.5% compared to 36.45 21.7% in normal elderly subjects (P c 0.01). This is presumed to reflect attrition of cortical motor neurons in the elderly, a finding consistent with reduced muscle strength and poorer motor skills that accompanies normal aging. In ALS, thenar MEP latency was slightly prolonged (23.15 2.5 msec compared to 21.1 f 1.7). However, the potential amplitude was markedly reduced (21.3 k 18.4%). In patients having predominantly pseudobulbar features, MEPs were often absent. In Huntington’s, Alzheimer’s and Parkinson’s diseases, the MEP was normal. However, it was reduced in amplitude in Guamanian PD in the absence of ALS reflecting occult motor neuron loss. Preliminary studies, employing conditioning electrical stimuli to the ipsilateral median nerve in Parkinson’s failed to demonstrate augmentation of the MEP that we encountered in normal subjects. This might be a sensitive measure of motor system abnormality in some degenerative neurological diseases.

KNEE EXTENSOR TORQUE AND SITTING POSITIONS. J. Ekholm,

K. Schiildt

(Karolinska

Hospital,

AND EMG

IN STANDING

and U.P. Arborelius Stockholm,

Sweden)

Measuring of leg muscle function in a standing position would be advantageous, since, for the legs, this is a more ‘functional position than sitting. The aims of the study were (i) to develop a method for measurement of knee muscular moments (torques) during a rising exertion in the standing position and (ii) to compare the results from knee extensors with those obtained in the sitting position. For the calculation of the knee and ankle moments in the standing position, the ground-to-foot reaction forces were registered by a force plate (Kistler) and the moment arms to the joint axes were measured on photos or video images, while the subjects’ maximum efforts of rising in the vertical direction were restrained by two rope-and-pulley systems attached to the floor and to a leather girdle around the waist of the subject. Normalized surface EMG was used. In the sitting position the knee extensor strength was isometrically measured. The maximum muscular torque of the knee extensors was smaller during the attempted leg extension at all Joint angles tested in the standing position at corresponding knee angles. The pattern of distribution of activity levels (EMG) in different leg muscles was different during rising

compared to knee extension in sitting; were less activated during rising.

POLYGRAPHIC SLEEP PATTERN ICS DURING ABSTINENCE.

of Psychiatry

IN MALE

K. Niedzielska

H. Ekiert, W. Jernajczyk, (Institute

the quadriceps

and Neurology,

muscles

ALCOHOL-

and B. Woronowicz Warsaw,

Poland)

All-night sleep EEGs were compared in two age-equivalent groups: 20 male chronic alcoholics during an abstinence period (aged 28-49 years) and 20 healthy men (aged 28-52 years). Alcoholics fulfilled clinical criteria: 20-29 points in an alcohol dependency diagnostic questionnaire, a history of heavy chronic alcohol abuse (mean 12 years), and prolonged abstinence (mean 21 weeks). Alcoholics had a significantly increased number of awakenings and a shorter actual sleep time than controls.

NEUROPHYSIOLOGICAL STUDY OF Mg-VALPROATE IN SYMPTOMATIC GENERALIZED EPILEPSY (SGE). M. Elia, R.M. Bergonzi (Institute

for

Colognola,

Research

R. Ferri,

on

Mental

S.A. Musumeci

Retardation

and

and

P.

Aging,

Italy) Long-term EEG monitoring can be considered a more reliable method than simple clinical evaluation in the follow-up study of the effectiveness of antiepileptic drugs (AEDs) by providing useful information on: (a) changes in EEG background activity due to therapeutic or toxic effects of AEDs on cerebral function; (b) reduction of interictal epileptiform activity due to then action. Until now only a few studies have reported on this topic and it is noteworthy that in only 80% of these was a correct statistical analysis of results performed. In addition, the reported EEG changes are descriptive rather than quantitative and vary greatly. For this reason we have carried out a more detailed and quantitative evaluation of the effects of Mg-valproate by analyzing overnight sleep EEG recordings. Ten subjects affected by SGE underwent 2 baseline recordings after 1 adaptation night. They were administered Mg-valproate (15 to 20 mg/kg/day) for 2 months. One control recording was performed after 1 month of treatment, and 2 more after 2 months. Sleep patterns, the number of spikes per min and the density of spikes in different sleep stages were quantified. Results and conclusions are discussed extensively,

RETT SYNDROME: HYPERVENTILATION AND EPISODIC EEGs.

APNOEA

M. Eiian and N. deM. Rudolf (Charing

Cross Hospital,

London,

U.K.)

EEG is the only laboratory investigation which often shows abnormalities in children with Rett syndrome. Fifteen girls