Freezing of gait (FOG) is a common symptom in advanced PD—PD that’s been diagnosed for at least five years. It occurs in 30% of PD patients with advanced PD, though it can also occur early in PD and may be one of the initial symptoms. FOG is characterized by “start hesitation” or “failure of gait initiation,” meaning the inability to start walking.
FOG also occurs when you turn, or when you think about turning. Suddenly you get stuck, your feet can’t move, as though they’re glued to the floor or held there by mag-nets, and you’re frozen like a statue—hence the name freezing of gait. FOG can occur when you come to a doorway or even think about coming to a doorway, when you come to a curb or think about coming to a curb. FOG may be accompanied by anteropulsion (a feeling of being pushed forward) or retropulsion (a feeling of being pulled backward).
It may be preceded by short, shuffling steps. FOG is often accompanied by postural instability, a feeling of being unbalanced. Common to all the situations that result in FOG is a change in your stride length and/or your stride velocity (or the thought of changing your stride length or velocity). It’s as though you want to do something, but your feet don’t like what you are doing (or thinking) and they refuse to move.
Starting to walk is like starting your car by turning on your engine, pumping your acceleration and releasing your brake. In start hesitation, it’s as though your brake can’t be released. In turning, approaching a doorway, or walking in a crowded room, your stride length and/or stride velocity must change. This is like taking your foot off your accelerator and pushing down on your brake.
In FOG it’s as though your brake locks and you can’t release it. FOG can be helped, in part, by learning “tricks,” much like jiggling with your brakes to get you started or to get you going again. Among the “tricks” that work in some patients and that we teach at the
Muhammad Ali Parkinson Clinic are the following: Teach yourself to step over a real or imagined line or lines on the floor to get yourself going. Somehow, parallel lines drawn on the floor, or imagined as being drawn on the floor, “trick” your feet into obeying your brain.
Carry a laser light, or a cane fitted with a laser light. Shine it on the floor and step over it, again, to get yourself going. Note: this trick doesn’t work in bright sunshine.
Carry a cane or a walking stick and tap it on the floor in synch with a tune you’re humming as you walk. Somehow, this combined visual and auditory trick allows your feet to continue walking even as you change your stride length and/or velocity.
Hum a tune, or snap your fingers, to start walking or to continue walking as you change your stride length and/or velocity.
Chant a phrase such as “Go, Go, Go,” or “Turn, Turn,
Turn,” to start walking or to continue walking.
If FOG occurs early, before you’re started on anti-Parkinson drugs, it will usually improve when you add a dopamine agonist (Mirapex, or Neupro, or Requip), an MAO-B inhibitor such as Azilect or Zelapar, aman-tadine, or levodopa/carbidopa. If FOG occurs after you’ve been started on levodopa/carbidopa, then adding a dopamine agonist, an MAO-B inhibitor, amantadine, entacapone (Comtan), or tolcapone (Tasmar) may help.
If FOG occurs after you’ve been started on a dopamine agonist, then adding an MAO-B inhibitor, amanta-dine, or levodopa/carbidopa may help.
If FOG occurs after you’ve been on levodopa/ carbidopa, try to determine if it occurs when the levodopa/carbidopa is working or when it is not. At the Muhammad Ali Parkinson Clinic, we ask patients who suffer from FOG to visit us in the morning, after they’ve stopped levodopa/carbidopa for at least 16 hours. We examine them and determine how often
FOG occurs, then give them a dose of levodopa/carbidopa and examine them after an hour. This allows us to determine what effect the medication has on FOG. We may then recommend additional levodopa/carbidopa or adding entacapone or tolcapone.