[Physical examination--measurement of muscle strength]. / Fysische diagnostiek--het meten van spierkracht.

Measuring muscle strength and establishing paretic symptoms are done first of all by having the patient perform actions or movements that require normal muscle strength. Measuring or grading the strength of separate muscle groups is usually done by means of the so-called Medical Research Council (MRC) scale that runs from 0 to 5, with the movement against gravity as an important criterion. This scale is not very valid in tract 4 (more strength than needed to overcome gravity, but still subnormal). Using a manual dynamometer or a fixed dynamometer it is possible to measure the strength of most clinically important muscle groups of the extremities and to compare them with values found in a normal population. For following the individual patient with a neuromuscular disorder, strength measurement with the dynamometer is more reliable than grading using the MRC scale.

The influence of handedness on the distribution of muscular weakness of the arm in facioscapulohumeral muscular dystrophy.

The strength of 10 muscle groups in both arms was measured using hand-held myometry to determine the influence of handedness on left-right differences of muscle strength in facioscapulohumeral muscular dystrophy (FSHD). Two groups of subjects were studied: 24 healthy volunteers (19 right-handed), and 53 patients (42 right-handed) with autosomal dominant FSHD. An opposite left-right difference of strength of shoulder and arm muscles was found: right-handed volunteers were stronger on the right side, right-handed patients were stronger on the left side. This opposite left-right difference was statistically significant for the supraspinatus muscle, the wrist extensors and the shoulder internal rotators. The number of left-handed subjects was too small for statistical analysis. The relation between handedness and increased muscle weakness in right-handed FSHD patients suggests that mechanical factors may play a distinct role in the progression of muscle weakness in FSHD.

Hand-held myometry: reference values.

In thirteen major muscle groups of 50 healthy females and 50 males, aged 20-60 years, maximum voluntary contraction was measured with a hand-held dynamometer. The intrasession variation, the left-right variation, and the fifth and fiftieth centile values were calculated. The ratio of two observations within one session ranged from 0.85 to 1.18 and the ratio of left to right ranged from 0.82 to 1.22 (95% reference limits). In 20 volunteers the repeatability was tested after one week. The ratio of averages of three measurements in two successive weeks ranged from 0.82 to 1.23 (95% reference limits). There were only small differences between muscle groups concerning these ratios. A significant relation with age and weight/Quetelet Index could be demonstrated in some muscle groups. The mean strength of females is approximately two thirds of the strength of males. The data may be useful as reference values in the application of hand-held myometry.

The "make/break test" as a diagnostic tool in functional weakness.

Strength was measured in four major muscle groups with a hand-held dynamometer. The "make" and "break" technique was used with and without encouragement, and fatiguability was tested in patients with organic weakness and patients with functional weakness. Patients with functional weakness could be distinguished from the other two groups by an increase in strength greater than 20% with the break compared with the make technique. Additionally they tend to show larger increases in strength with encouragement and their "fatiguability" was less.

Tizanidine versus baclofen in the treatment of spasticity in multiple sclerosis patients.

Sixteen patients suffering from spasticity due to multiple sclerosis were treated with baclofen and tizanidine in a partially blind cross-over study. No significant difference in efficacy was found. The most striking difference was seen in the side-effects: baclofen frequently caused more or less severe muscle weakness and even falling during walking and standing. Treatment with tizanidine produced an apparent improvement of mobility in some patients suffering from moderate or marked paresis associated with a marked spasticity of their legs. Isometric muscle strength did not show any significant changes during either treatment. The different impact of baclofen and tizanidine on mobility and weight support seems to be related to their different site of action in spasticity.

Measuring muscle strength.

A dynamometer that can be held in the hand and that was designed to measure muscle strength in a simple way in the range 2-5 of the MRC scale, was tested in order to establish to what extent differences in results can be attributed to the observer, the subject and replication. Observers learned the technique quickly and their results agreed with each other to a considerable extent. The subjects showed a small learning effect in three of the four muscles tested. Normal muscle strength was measured in one hundred 18-year-old men.