Mechanical properties in dysthyroid myopathy.
Isometric active force and passive load were measured quantitatively in five patients with dysthyroid myopathy during the alert state, to analyze the mechanism of ocular motor disturbance. The results were as follows: (1) the active forces in both agonist and antagonist muscles working in the direction of ocular limitation showed normal values and functioning according to Hering's laws; (2) increasing the passive load of the antagonist muscles consistently demonstrated a close correlation to ocular motor disturbance, but some other muscles also showed abnormal stiffness without clinical signs, and (3) muscle enlargement identified by coronal computed tomography scan was not necessarily related to increased passive load.
Department of Ophthalmology, Sapporo Medical College, Japan.
Y
Y
Igarashi
K
K
Ogasawara
H
H
Maekawa
H
H
Ohyachi
M
M
Ohba
D000328:Adult; D000368:Aged; D005133:Eye Movements; D005260:Female; D006111:Graves Disease / Q000503:physiopathology*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D008875:Middle Aged; D015835:Ocular Motility Disorders / Q000503:physiopathology*; D009801:Oculomotor Muscles / Q000502:physiology*