Tasks of attention augment rigidity in mild Parkinson disease.
OBJECTIVE
The purpose of this study was to determine whether tasks involving effortful attention would cause augmentation of rigidity in patients with mild Parkinson disease.


METHODS
In 17 subjects with mild Parkinson disease, rigidity in a single arm was assessed during various experimental conditions by a blinded movement disorders neurologist. Rigidity was scored separately at the wrist and the elbow using an ordinal scale. In three of the conditions, sustained attention was directed toward visual, auditory or movement-related stimuli. Two varieties of Froment maneuver served as positive controls: contralateral hand opening-closing or ipsilateral foot tapping. In addition, rigidity was assessed twice with subjects resting. The examiner was unaware of the sequence of experimental conditions and this was changed for each subject. Mean rigidity scores for the various experimental conditions were compared against the baseline state (an average of both trials with the patient resting) using a repeated measures ANOVA and post-hoc Tukey-Kramer multiple comparisons test.


RESULTS
Rigidity was significantly increased from baseline with each of the attentional tasks (p < 0.01 to p < 0.001) and also with the two Froment maneuvers (p < 0.001). Rigidity augmentation with contralateral hand opening-closing was significantly greater than with any of the attentional tasks (p < 0.05 to p < 0.001).


CONCLUSIONS
Tasks of effortful attention did appear to augment rigidity in patients with mild Parkinson disease. We speculate that the greater augmentation seen with the Froment maneuver could have an anatomic basis.
Mendonça
Dan A
DA
Grand River Hospital, Kitchener, Canada.
Jog
Mandar S
MS
D000368:Aged; D000369:Aged, 80 and over; D001288:Attention / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009127:Muscle Rigidity / Q000503:physiopathology*; D010300:Parkinson Disease / Q000503:physiopathology*