June 9, 2011 (Toronto, Ontario) — A new report confirms and expands a previous observation that cycling ability appears to be preserved in most patients with Parkinson's disease (PD), even those with severe freezing of gait.

The finding could open doors to freedom of movement and exercise for patients with PD, says lead author Anke Snijders, MD, from the Donders Institute for Brain, Cognition and Behavior at Radboud University Nijmegen Medical Center in the Netherlands.

Dr. Anke Snijders

The results were presented here at the Movement Disorders Society 15th International Congress of Parkinson's Disease and Movement Disorders.

Extends Early Observation

Last year, Dr. Snijders, in collaboration with senior author Bastiaan R. Bloem, MD, PhD, from the Donders Institute for Brain, Cognition, and Behavior at Radboud University Nijmegen Medical Center, described the case of a 58-year-old patient with advanced PD and severe gait problems who could nonetheless ride a bicycle for up to 15 miles per day. Immediately on dismounting the bike, his gait freezing recurred.

Their case report was published in the April 1, 2010, issue of the New England Journal of Medicine and was reported by Medscape Medical News at that time.

A video posted with the report shows the patient trying to walk, helped initially by cues, but then unable to continue. But during an interview, he disclosed that he was able to ride his bike for miles every day, Dr. Bloem said in an interview at that time. "I said, this is impossible; it can't be, but he said no, he could ride, and he really wanted to demonstrate this to me."

Patient with Parkinson's disease riding a tricycle

Outside, Dr. Snijder provided her bike for the demonstration. "She put him on it, gave him a little push, and as you can see in the video, off he went," Dr. Bloem said. "He circled just fine, made a perfect U-turn, and on his return, he actually climbs on the pedals. When he returns, he hops off the bicycle and is immediately frozen to the ground again. It's really a stunning observation."

The researchers have since reported the case of a second patient in a subsequent publication in Movement Disorders.

These case reports, Dr. Snijders said in an interview here, "caught a lot of attention, so we wondered if this was something that was just the case in these 2 patients and makes them special or whether this is really something which is general in Parkinson's disease and freezing of gait, that they are able to cycle despite having freezing of gait during walking."

In a new report presented here, the researchers carried out a semi-structured interview in 53 consecutive outpatients with PD about freezing of gait during walking and cycling. They excluded 11 patients who had never cycled or stopped cycling many years earlier for reasons unrelated to freezing of gait.

Of the remaining 42 patients, 23 were "freezers" with marked freezing of gait, and 19 were "nonfreezers."

Among the 23 freezers, only 1 had similar freezing episodes while cycling, "but these were a lot less frequent and less severe than the blocks suffered during walking," Dr. Snijders noted.

Another 8 of the freezers (35%) reported that they had irregular pressure in the pedals, although without overt blockade, compared with none of the nonfreezers. Three of the patients with freezing of gait, however, reported other problems with cycling, such as being unable to mount a bicycle (3 patients) or maintain their balance on a bicycle (4 patients).

"So these Parkinson's disease patients show a preservation of cycling abilities even with marked freezing of gait," Dr. Snijders concluded.

Their findings also support another observation previously reported by Dr. Bloem and another colleague, Majorie Aerts, MD, also from Nijmegen, that parkinsonian patients who are still able to cycle are more likely to have idiopathic PD. "When they are not able to cycle, that is a red flag for atypical parkinsonism," Dr. Snijders added, a phenomenon that has been dubbed the "bicycle sign."

Their study of this phenomenon was published in The Lancet earlier this year and reported by Medscape Medical News at that time.

The precise mechanisms underlying the preserved cycling ability remain to be determined, but the authors consider several hypotheses. For example, the moving pedals could generate external tactile cues, or cycling may involve a different and better-retained motor program compared to walking. Compared to walking, cycling may also involve different loading reflexes, less demand on integrating postural adjustments, a greater amount of visual input, or different attentional demands, they speculate.

Whatever the mechanism, this preserved cycling function offers the heady possibility of exercise training for these patients, the authors conclude. In PD, the inactivity and sedentary lifestyle brought about by the disease's effects on motor function also work to compound other symptoms of PD, such as depression, constipation, cognitive decline, and cardiovascular and cerebrovascular disease, they point out.

Cycling — using either a real bicycle outdoors or, as a safer alternative (particularly for those with balance disturbances), a tricycle or even a stationary or recumbent bicycle at home — may offer an attractive way to promote physical activity in PD to prevent the many complications of immobility.

Useful Physical Exercise

Commenting on these findings, Daniel Tarsy, MD, from Beth Israel Deaconess Medical Center in Boston, points out that recent anecdotal reports suggest that patients with PD who have freezing of gait can ride a bicycle much more easily than they can walk.

"The study by Snijders indicates this may be a relatively common phenomenon," he said in a statement from the Movement Disorders Society. "Only 1 of 23 patients who reported gait freezing experienced similar difficulty while cycling."

"If this can be confirmed by direct observation, it indicates that individuals with gait freezing can enjoy useful physical exercise," Dr. Tarsy added. "Whether this occurs by utilizing an alternative motor system, taking advantage of sensory cues provided by the rotating bike pedals, or by other mechanisms, is of great interest and will be worth investigating."

The study was supported by the Prinses Beatrix Fonds and by a research grant from the Netherlands Organization for Health Research and Development. Dr. Snijders has disclosed no relevant financial relationships.

Movement Disorders Society (MDS) 15th International Congress of Parkinson's Disease and Movement Disorders: Abstract 591. Presented June 8, 2011.

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