Eye movement disorders in myotonic dystrophy type 1.
CONCLUSIONS
No definite sign was found of central oculomotor system disorders being independent of saccadic slowing because (1) diminished maximum slow phase velocity of the optokinetic nystagmus (OKNspv) was closely related to saccadic slowing (p<0.01, r=0.59), (2) maximum frequency of optokinetic nystagmus (OKNfq) was normal, (3) visual suppression (VS) change was mild, and (4) the diminished maximum slow phase velocity of the caloric nystagmus (CNspv) seen in some patients is explained by both peripheral and central vestibular involvement. These findings support the extraocular muscle hypothesis.


OBJECTIVE
To assess whether eye movement disorders seen in patients with myotonic dystrophy type 1 (DM1) are caused by central oculomotor system involvement or extraocular muscle damage.


METHODS
Oculomotor functions and their correlation with (CTG)n length were studied in 29 DM1 patients and 12 age-matched controls.


RESULTS
Values for saccadic velocity (p<0.005), maximum OKNspv (p<0.005), and maximum CNspv (p<0.01) in the patient group were markedly lower than in the control group. VS of caloric nystagmus in the patient group was slightly lower than that in the controls. No significant difference was found between the two groups in the maximum OKNfq. Patients with greater (CTG)n lengths had lower saccadic velocities (p<0.01, r=0.71).
Osanai
Ryuichi
R
Department of Otolaryngology, Kashiwa Kousei General Hospital, 3-8-20 Akebono, Kashiwa, Chiba, Japan. CBA01622@nifty.com
Kinoshita
Masanobu
M
Hirose
Kazuhiko
K
D000328:Adult; D000368:Aged; D004247:DNA / Q000032:analysis; D004584:Electronystagmography; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009223:Myotonic Dystrophy / Q000150:complications* / Q000235:genetics; D017120:Nystagmus, Optokinetic / Q000502:physiology; D009760:Nystagmus, Physiologic / Q000502:physiology; D015835:Ocular Motility Disorders / Q000150:complications* / Q000503:physiopathology*; D012438:Saccades / Q000502:physiology*; D018911:Trinucleotide Repeats / Q000235:genetics
D004247:DNA