A comparison of the findings in two unrelated Dutch patients with chondrodystrophic
myotonia with those in the patients reported so far may contribute towards a more
exact delineation of the syndrome:
The skeletal system is involved in many ways. The patients are dwarfs with a retarded
skeletal growth but with a normal head circumference. Other abnormalities are: high
arched palate, short horizontal arch of the mandible, low implantation of ears, pigeon
breast deformity, flattened vertebrae, dysplastic hips and talipes. There are many
expressions of the affliction of the muscular system. It is firmly hypertrophic in
the boys and normal or partially hypo- or hypertrophic in the girls. There is myotonia
in many muscle groups. The blepharospasm, the frozen smile, the high pitched nasal
voice, stridulous respiration, and the impaired range of motion (mostly in the proximal
joints), are most probably results of the muscular involvement. Enzyme studies and
biopsy studies by the light- and electron microscope revealed myopathic features in
most of those reported in the literature and in both of our patients. In both of our
patients, an elevation of the first fractions of the L. D. H. isoenzymes, myopathic
phenomena in the E. M. G. and an increased average fiber diameter were discovered,
which have not been reported up to now. Some subclinical muscular abnormalities were
traced in the family members of our patients. The intelligence of the patients is
mostly normal; the syndrome is not manifest until in the third year of life. There
appears to be an autosomal recessive heredity. Treatment is restricted to physical
therapy. Prognosis is presently unknown.
Myotonia - blepharospasm - muscular hypertrophy - dwarfism - skeletal deformities
