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Asymmetric Gait May Predispose Patients With Parkinson's Disease to Gait Freezing: Presented at MDS

By Paula Moyer

ROME, ITALY -- June 16, 2004 -- Patients with Parkinson's disease who have an asymmetric gait rhythm may be predisposed to freezing of gait, according to findings presented here June 15th at the 8th International Congress of the Movement Disorder Society.

"Freezing of gait is a very disturbing symptom to patients with Parkinson's disease," said principal investigator Meir Plotnik, PhD, senior researcher, movement disorders unit, neurology department, Tel-Aviv Sourasky Medical Center, Tel-Aviv, Israel. "We hope that by understanding its pathogenesis we may develop strategies to help alleviate freezing and improve patients' quality of life."

The investigators undertook the study because earlier research had suggested that patients with freezing of gait had a less rhythmic, more variable gait than that of patients who are spared gait freezing. Dr. Plotnik and his coinvestigators rationalized that gait would be halted once impaired bilateral coordination of gait exceeds a certain level.

Therefore, they studied the relationship between gait freezing and asymmetric rhythmic motor performance in both the upper and lower extremities, to discern whether predisposing differences in asymmetry were confined to walking, or whether they were systemic.

The investigators recruited 30 patients with Parkinson's disease, 21 with gait freezing and 9 without. Participants' disease severity ranged between 2.5 to 3.5 on the Hoehn and Yahr scale. They were tested in an "off" state, defined as 12 hours without levodopa mediation, and again in an "on" state, in which they had taken some formulation of levodopa.

Subjects wore force-sensitive insoles that measured the timing of each gait cycle while they were walking at a comfortable pace. For each subject, the observers calculated the percentage of swing time, or the time a foot is in the air, and averaged the swing time across strides for the left and right foot. The study design defined gait asymmetry parameter (GAP) as equalling the swing time ratio between the right and left foot.

The investigators used the timed motor tests of the Core Assessment Program for Intracerebral Transplantations (CAPIT) to assess upper limb asymmetric performance. The program measured the times required for the subject to complete 20 cycles of alternating taps of palm and dorsum of the hand, 20 successive taps of two points 30 cm apart, and 10 repetitions of tapping the thumb to each finger in succession. Each hand's performance was measured and totalled. The CAPIT asymmetry parameter was defined as equalling the ratio between the total for the right and left hands.

Results show that gait was more asymmetric in patients with gait freezing than in those without, Dr. Plotnik said. In the "off" state, the average GAP scores were 0.19 for those with gait freezing and 0.12 for those without. In the "on" state, the scores were 0.14 for those with and 0.04 for those without freezing. In the "on" state, the difference between the groups was statistically significant (P < 0.02). The investigators also found that the GAP score was significantly and directly related to gait variability (R =.61; P <.001).

Average CAPIT scores were almost identical in the 2 groups in both states; therefore, the investigators concluded that upper extremity asymmetry of rhythm was unrelated to gait freezing.


[Presentation title: Is Freezing of Gait Related to Asymmetric Rhythmic Motor Performance in Patients With Parkinson's Disease' Abstract P509]

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