Stapedial Reflex in Parkinson’s Disease

Abstract

In 27 patients with Parkinson’s disease (PD), stapedial reflexes were measured using impedance audiometry and compared with those of 11 age-matched control subjects. The reflex threshold of PD patients was lower than that of control subjects. A prolongation of contraction time (C₅₀) and relaxation time (D₅₀) was revealed. Between patients with and without L-dopa, there was no significant difference for any reflex parameter. But, the D₅₀ of patients without anticholinergic drugs was longer than that of patients with anticholinergic drugs. The authors could not find any relationship between the severity of PD and the reflex parameters. The authors assume that the prolongation of reflex parameters might be attributed to the hyperactivity of the indirect pathways of the stapedial reflex.

Loudness perception and speech intensity control in Parkinson's disease

“…Aside from the research by Murofushi et al (1992) on the stapedial reflex in PD, little effort has been made to connect the problems of hypophonia and loudness perception in PD to specific auditory processes. Another strength of this study is that it appears that this is the first study to investigate the effects of background noise in magnitude estimation and magnitude production tasks in a group of individuals with PD.…”

Stapedial reflex in myotonic dystrophy type 1 and CTG repeat expansion

“…In the present reported study, we found (1) no significant difference between the pure tone audiometric thresholds in the DM1 patients and in the control subjects (at 500 Hz); (2) no significant difference between the SR thresholds in the patients and in the control subjects (500 Hz stimuli); (3) that both C 50 and D 50 in the DM1 patients were significantly prolonged, whereas L was not; (4) and that both C 50 and D 50 in the patients were significantly correlated with (CTG)n length, whereas L was not. Prolonged contraction time (C 50 or corresponding parameters) has been reported in spastic dysphonia [7], multiple sclerosis [4,11,12,18] and Parkinson's disease [20], whereas prolonged relaxation time (D 50 or corresponding measures) has been reported in multiple sclerosis [11], progressive muscular dystrophy [16], sensorineural hearing loss [21], spasmodic dysphonia [19] and Parkinson's disease [20]. Murofushi et al [20] speculated that prolongation of both C 50 and D 50 in Parkinson's disease was caused by hyperactivity of the indirect SR pathway in the brainstem reticular formation.…”

“…Prolonged contraction time (C 50 or corresponding parameters) has been reported in spastic dysphonia [7], multiple sclerosis [4,11,12,18] and Parkinson's disease [20], whereas prolonged relaxation time (D 50 or corresponding measures) has been reported in multiple sclerosis [11], progressive muscular dystrophy [16], sensorineural hearing loss [21], spasmodic dysphonia [19] and Parkinson's disease [20]. Murofushi et al [20] speculated that prolongation of both C 50 and D 50 in Parkinson's disease was caused by hyperactivity of the indirect SR pathway in the brainstem reticular formation. In DM1 patients, however, it is natural to consider that prolongation of C 50 reflects muscle weakness and that of D 50 myotonia, because there is no evidence of the hyperactivity of the indirect reflex pathways in the brainstems of DM1 patients.…”

“…All the study subjects were required to have a normal hearing level (Ϲ 30 dB HL) at 500 Hz, normal tympanograms, the presence of SR at 500 Hz, and no reflex decay at 500 Hz [20].…”

“…Amplitude was defined as the difference between the highest and lowest impedance values [20]. The absolute SR amplitude value was measured but not investigated statistically, because of wide variation in SR amplitudes between individuals, even in the control subjects [23].…”