ELECTROMYOGRAPHY OF MIDDLE EAR MUSCLES IN MAN DURING MOTOR ACTIVITIES

Abstract

From the Departmvnt of Ear, Nose, and Throat, Kommunehospitalet, Copenhagen. (J. Falbe-Hansen, A1.D.) ELECTROMYOGKAPHY O F MIDDLE EAR MUSCLES IN M4N DURING MOTOR ACTIVITIES GERHARD SALOMON1 and ARNOLD srARR2 Thc rnidtlle ear musclcs contract in rcsponse to sounds and modify sound transmission between the ear drum and the cochlea W i g g e r s (1937). These muscles have therefore been traditionally considered to serve acoustic functions Liischer (1930), Hallpike (1935), Metz (1946), Jepsen (1955), Kirikae (1960), Perlman (1960). However, recent animal experiments reveal the middle ear muscles to contract during general- ized motor activities Carmel & Sfarr (1963). These findings suggest that the middle ear muscles may also have important non-acoustic functions. The present studies were undertaken to determine whether the middle ear muscles in man may similarly contract during motor activities. Our findings correspond closely to the recent animal experi- ments and define a number of motor patterns that may be accompanied by activation of the middle ear muscles. MATERIALS AND METHODS Middle ear muscle activity was studied by means of elcctromyography in two patients.3 The first patient (RJ), aged 42, had Iongstanding tinnitus and vertigo, secondary to traumatic inner ear damage. Threshold average air conduction (TAA) was 60 db in the affected car. Acoustic and caloric functions were normal in the other car. One week prior to a therapeutic labyrintheetomy, two stainless steel wire electrodes (each 125 B i n diameter) were implanted about 2 mm apart into the tensor tympani in the affected ear. The second patient (WO), aged 45, had a chronic, drx perforation of the tympanic membrane. TAA was 40 db. On the day of tympano- plasty, a single stainless steel electrode was placed into the tendon of the stapedius muscle. Middle ear muscle activity was recorded by an electromyograph, DISA Recipient of a research fellowship from University of Copenhagen. 2 This work was supported in part by Special Fellowship BT-962 from the National Institute of Neurological Diseases and Blindness, U. S. Public Health Service. 3 One of the authors ( G S ) gained experience with t h e experimental techniques as a rc\ult of work on cats carried out in the Institute f o r Experimental Research in Surgery. Director H . H . Wandall, M.D., D.M. Sc.