Wednesday, April 19, 2017

“Pusher” Syndrome-- the neuroplastic model of recovery

Pusher syndrome (PS) is an altered sense of reality. 

Survivors with PS (sometimes known as "pushers") believe that they are sitting or standing “upright” when they are tilted approximately 18° towards the "bad” side. 

Therapists may be exacerbating pusher syndrome. When survivors with PS are forced to a “upright” they feel like they're leaning too far towards the "bad" side. “Pushers” react to this feeling by leaning towards the affected side. They see any attempt to get them truly straight as a serious threat that inspires fear. 

Another term for pusher syndrome is listing phenomenon. This may be a more accurate term because "pushers" only become "pushers" when they are pushed. Anyone who was shoved 18° out of balance would push back! There are other terms that have been used for PS including:
·       ipsilateral pushing
·       contraversive pushing
·       pusher behavior.

PS affects approximately 5% (although some estimates are as high as 50%) of all stroke survivors.

Survivors with PS have had damage to portion of the brain that controls the feeling of upright body posture. The area damaged is called the posterolateral thalamus. Loss of this area causes PS.

Balance is determined by 3 systems: vision, vestibular (inner ear) and proprioception. Patients with PS typically only have damage to one of the 3 systems: proprioception. Clinicians can help by directing patient focus to the balance systems that are still intact. Therapists can help pushers by helping them to attend to vertical visual cues. One technique involves having the therapist sit in front of the seated patient. Then use any visual cues available in the room, or the therapist’s own body (i.e. the forearm held vertically) to have the patient reorient themselves to true vertical. Carr and Shepard (reference below) suggest having the patient purposely, and within a safety-controlled environment, repeatedly reach for an object towards the hemiparetic side. The patient is then instructed to bring themselves back to visually confirmed true vertical. This simple technique hits on two basic concepts of the neuroplastic model; task specificity (reaching for an object creating a challenge to balance) and repetitive practice. The repetitive practice in this case is repeatedly reorienting to true vertical. Therapists can help pushers by teaching the necessary movements needed to realign to vertical. As is true with many of the recovery options that drive neuroplastic change, it is repeated self-correction that rewires the brain.

Pushers should be encouraged to hold a vertical position no matter what everyday task they’re doing. This incorporates another core concept in the neuroplastic model: massed practice. Therapists who encourage constant realignment to true vertical—in and out of the therapy gym—help the survivor mass their attempts at righting and equilibrium reactions.

Although certainly not proven, I would bet that the rewiring necessary to correct PS does not happen in the thalamic region—the region damaged in stroke survivors with PS. Using repetitive, task specific massed practice may instead force an enlargement and/or strengthening of the cortical representation of the intact vestibular and visual systems. 

Therapists can help PS patients by providing shepherding guidance on this necessary neuroplastic journey.

1. Karnath HO, Broetz D. Understanding and treating "pusher syndrome". Phys Ther.2003 Dec;83(12):1119-25. 
2. Shepherd RB, Carr JA. Response to Discussion Paper: New aspects for the physiotherapy of pushing behaviour, D. Broetz and H.-O. Karnath, Neurorehabilitation 20 (2005), 133-138. NeuroRehabilitation. 2005;20(4):343-5.  


Linda said...

I am not sure I fully qualified as having this but I sure was leaning that way. (pun intended) The dizziness, nausea, and overwhelming sense of falling and panic are not all that conducive to making you want to keep practicing those problematic movements. I also learned that throwing up on your therapist makes the sessions much shorter. sigh. Sitting a little sideways seems okay in the moment and people telling you to sit up straight get very annoying.

Working on the dizziness and on "where is up?" was by far the hardest task in my recovery. I find that there are still odd triggers that can throw my orientation.

Peter G Levine said...

Thanks Linda; I'm wondering if what your talking about is pusher syndrome or one of the dozens of other sequalae and comorbidities that might explain your continuing symptoms.

Linda said...

Thanks Peter. I am now doing very well now. It has been a long time now and only a few rarer triggers can incapacitate me. No Disneyland rides for me. grin

Your post made me remember rather clearly a whole lot of times when therapists were trying to get me to sit more upright, walk straighter and literally pushing me over (upright?) from the weaker side and me thinking that I was about to fall over to the other side along with waves of nausea.

Early on I saw a really good Physiotherapy professor who specialized in Neuro issues. Her very specific recommendations to my outpatient physiotherapist made a world of difference. She believed my vestibular system was not recognizing any information from one side. I also had limited or weird sensation in my foot. It took a lot of time and therapy but it really got my life back.

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