Ocular fixation instabilities in motor neurone disease. A marker of frontal lobe dysfunction?
OBJECTIVE
Eye movements are classically felt to be spared in motor neurone disease (MND). Although a range of ocular motor disorders have been reported, no consistent pattern has been established. Disturbances of ocular fixation have been noted in MND; however, fixation has not yet been formally examined. With the recent characterization of ocular fixation using saccadic intrusion amplitude and fixation periods, we performed a cross-sectional study to examine for abnormalities of ocular fixation in non-dementing patients with MND.


METHODS
A total of 44 patients and 45 controls were recruited. Fixation was examined using infra-red oculography and all subjects then underwent a neuropsychological evaluation.


RESULTS
Saccadic intrusion amplitude was found to be greater in patients compared to controls and in particular, spinal-onset patients. Saccadic intrusion amplitude in patients correlated with neuropsychological measures sensitive to lesions of the frontal lobes.


CONCLUSIONS
This is the first study to identify abnormalities of fixation in MND and these results indicate that ocular fixation instabilities may be a marker of the sub-clinical frontal lobe dysfunction in MND. A longitudinal study to examine if saccadic intrusion amplitude deteriorates with time would be of interest as this could provide a quantifiable objective marker of disease progression.
Donaghy
Colette
C
Dept. of Neurology, Royal Victoria Hospital, Belfast, N. Ireland. donaghy1a@hotmail.com
Pinnock
Ralph
R
Abrahams
Sharon
S
Cardwell
Chris
C
Hardiman
Orla
O
Patterson
Victor
V
McGivern
R Canice
RC
Gibson
J Mark
JM
D003430:Cross-Sectional Studies; D053483:Eye Movement Measurements; D005260:Female; D005403:Fixation, Ocular; D005625:Frontal Lobe / Q000503:physiopathology; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D016472:Motor Neuron Disease / Q000150:complications*; D009483:Neuropsychological Tests; D015835:Ocular Motility Disorders / Q000150:complications*; D012438:Saccades