[Selective impairment of downward gaze; report of two cases of midbrain and bilateral paramedian thalamic infarction].
Selective paralysis of downward gaze, first described by André-Thomas et al. in 1933, is rare to be observed and not many cases have been so far reported in the literature. Two additional cases of selective impairment of downward gaze have been reported. X-ray CT scan revealed the infarcted areas in the midbrain tegmentum and bilateral paramedian thalami in both cases. Angiographic studies have revealed that the arteries occluded might be the paramedian thalamic arteries and their mesencephalic branches. According to the reported clinico-pathological studies and, in addition, to the results of the physiological studies in animal models, the responsible site of lesion for downward gaze failure is thought to be the rostral interstitial nucleus of MLF (riMLF). In one of the cases (28 year-old female, case 1), while vertical slow pursuit eye movements and upward saccade were normal in speed and range, maximum speed of eyes in voluntary downward saccade was markedly reduced and the eyes moved down slowly as if moving in oil (slow eye movement, viscosité). Passively extending the patient's head while she tried to fix her eyes on an unmoving object (doll's eye phenomenon), the speed of her eyes in downward saccade did not increase. In the other case (45 year-old male, case 2), the patient's voluntary and reflex downward eye movements were completely impaired and he could not look down nor follow the object below extending the horizontal meridian level. With regard to the unique features of abnormal eye movements observed in our cases, the possibility of coexistence of saccadic and slow pursuit eye movement systems in the vertical plane was discussed.
Kitano
K
K
Hirayama
K
K
Tokumaru
Y
Y
Furumoto
H
H
Komatsuzaki
A
A
D000328:Adult; D002544:Cerebral Infarction / Q000150:complications* / Q000000981:diagnostic imaging; D005133:Eye Movements; D005260:Female; D006801:Humans; D008636:Mesencephalon / Q000098:blood supply*; D009886:Ophthalmoplegia / Q000209:etiology* / Q000503:physiopathology; D013788:Thalamus / Q000098:blood supply*; D014057:Tomography, X-Ray Computed