PDOC emergence criteria

Discerning if a patient with an acquired brain injury has emerged from a Prolonged Disorder of Consciousness (PDOC) requires in-depth assessments by specially trained clinicians.

The current criteria for emergence from a minimally conscious state is defined by the US Aspen Work Group (2002) as “reliable and consistent functional interactive communication or the functional use of objects”.

Emergence requires a patient to give 6/6 correct responses in either functional communication or use of objects on two consecutive occasions.

Patients with a brain injury are likely to have a range of ongoing impairments that make achieving reliable and consistent results within this criteria problematic. Therefore the Guideline Development Group (GDG) proposed an extended set of parameters which also includes discriminatory choice making (successfully choosing between two objects).

However the ongoing impairments experienced by brain injury patients do not always present clearly, providing additional challenges to clinicians assessing them. 

In this EveryExpert article, we draw upon the case study of LW, a young man with diffuse axonal injury (DAI), and explore the challenges of meeting the emergence criteria for PDOC, especially if an individual has very complex needs.

Plus we consider the assessment from the clinician’s perspective and speak with Kirsty Allison, Senior Neuro Occupational Therapist from The Bridge Neurological Centre. We discuss the challenges of assessing a patient with unclear presentation and the importance of using a patient’s identified strengths to achieve the consistent responses needed to determine emergence.

LW case study

LW, a young man from Aberdeen in his early 20s, suffered DAI and subsequent severe brain trauma following a car accident in 2016. He was placed in an induced coma initially, ventilated via a tracheostomy and met the markers for being in vegetative state. He spent the following seven months in hospital, the first month in ICU and the following six on the neurophysiology ward. He then moved to a neurological care centre in Scotland where he underwent a SMART assessment which assesses potential awareness in adults with severe brain damage.

He received an indicative PDOC diagnosis with minimal consciousness, but because LW’s presentation was complex, the prognosis for his future was unclear. Assessments were further complicated by optic nerve damage to LW’s left eye, and it was not clear what level of vision had been retained, plus he had increased physical care needs. LW had developed type 2 diabetes since his brain injury and was insulin dependent. He had a PEP mask and a PEG, and used a phoenix postural chair.

LW returned to his family home to live in a specially adapted annexe with 24-hour care support. Once home, LW’s family, in particular his mum, noticed ongoing improvements and changes, notably responses to verbal commands and humour, and at times the content of conversations. LW began to use a communication device created by his dad (a spinning wheel of pictures), that he could trigger on cue although he could not consistently stop on a particular item cue, and had started to ‘fist bump’ without prompts.

Keen to explore the possibility of further improvements and the benefits of ongoing expert assessment, LW’s family requested a referral to The Bridge Neurological Centre in Middlesbrough.

LW was admitted to The Bridge in November 2023 and each therapy discipline within the specialist multidisciplinary team (MDT) conducted initial assessments to gain further understanding into the current indicative PDOC diagnosis using the Coma Recovery Scale-Revised (CRS-R).

Once clear on LW’s diagnosis, the team would then design a holistic sensory programme to build on strengths observed in assessment to date and identified earlier during the CRS-R.

A clinician’s perspective

Kirsty Allison, Senior Neuro Occupational Therapist, led LW’s initial assessments at The Bridge Neurological Centre. Understanding the exact presentation of LW was crucial for an accurate assessment but as Kirsty explains this took a great deal of time and continued monitoring to figure out. 

Kirsty says: “The emergence criteria for PDOC is very specific i.e. repeated success at certain tests performed under controlled conditions. So my first challenge was to understand how to accurately assess LW, with the specific abilities that he had, to prove that he'd emerged. For example, we knew that he could make limited movement with his arms, and we knew that he had some vision, but our challenge was to coordinate his abilities so his functional responses were optimised. 

“There are certain things that we knew just by looking at him - his pupils weren't in line, so he was definitely going to have some degree of double vision. He also has some nystagmus (uncontrolled movements), therefore using eye movements to communicate was not a reliable option. Utilising ‘yes’ and ‘no’ cards was also problematic in case they were positioned in an area of his visual field where there was no sight, or perhaps he was only able to see one of them. Plus due to LW’s nystagmus, he would also only briefly look at cards, so this created uncertainty about whether or not he actually looked at it.”

Visual clarity 

Understanding LW’s vision and what had been retained after the optic nerve damage to his left eye was a priority for Kirsty.

Kirsty says: “I was particularly interested in the visual elements of the CRS-R and each time I repeated it, I'd get a little bit more information about his vision and a bit more of an idea. Initially we realised he was inattentive on the left hand side relatively consistently, both voice as well as visual. We then completed lots of tracking and scanning work with light-up balls and eye-catching objects. We could see, even if it was briefly, that there were certain areas of his vision where he could track them. 

“So I had to literally map out his visual field and where he could track - I drew it out section by section. Then when I could see it laid out in front of me, I had that light bulb moment, and after many weeks I knew what it was – hemianopia. LW lost the sight in the right hand side of his right eye and the right hand side of his left eye. We also know that because he's got a deviated gaze, he has double vision as well. And he has an inattention to the left hand side on top.”

“It was like putting all the pieces together of a jigsaw when we finally realised what he could see. With this understanding we could help support his vision to give him the best chance possible in the assessments.”

MDT approach

Kirsty worked closely with Mira Bour Akbar, Speech and Language Therapist (SLT) at The Bridge, and through delivering joint sessions they had a breakthrough in their understanding of LW’s presentation. As Kirsty explains this was a pivotal moment in their work. 

Kirsty says: “We realised that if we used his right arm without support then he wouldn’t be successful, because the independent movement he has is within part of his visual field that he can't see. Therefore if we tried to get him to point to something or touch something, he couldn't do it because he couldn't see it. But if we facilitated his right arm to where he can see, then he was able to respond accurately. Within a few weeks he was consistently responding to familiar items such as his own photographs. So he had that potential the whole time, it was just that nobody had figured out how to tap into it.

“Of course, while we were doing these exercises, we always had the emergence criteria in the backs of our mind. Effectively LW was completing discriminatory choice making, so we knew he was making progress within his individual areas of strength. One day he successfully completed six out of six trials.

"We showed LW 12 pictures, two pictures at a time, one on top of the other, in his strongest line of vision (the left side of his right eye) while applying an eye patch to his left eye to help assist with the diplopia. To assist with mobility, we de-weighted his arm and facilitated it to a position where he could see his hand. We then asked him to touch one of the two pictures, e.g. “touch the picture of your mum”. 

This successful score met the emergence criteria, but we needed to repeat it within either 48 or 72 hours. So the next day he was doing a session on the tilt table with the physios and I used that as an opportunity to reassess him. He scored another six out of six, and that counted as reaching the emergence criteria for the first time. It was wonderful for him and his family.”

Looking to the future

Since meeting the emergence criteria LW has continued with his rehabilitation, which as Kirsty explains, has been tailored to his individual needs, building on his identified strengths.

Kirsty says: “We built on LW’s success in meeting the emergence criteria by creating custom yes and no cards to fit into his line of vision. We began by giving him simple commands, e.g. “touch the yes/touch the no”, and built on this to answering simple questions e.g. “do you have a brother?” His consistency and tolerance has improved with repetition. 

“LW is currently able to answer around 10 questions and his accuracy is approximately 90%, which has continued to improve. We have also re-introduced the spinning communication wheel, made by his dad and previously used at home. LW is able to answer around five questions using this tool before requiring rest. He also has spontaneously used the wheel to answer questions without additional cues from the team.”

“Now that we have a better understanding of where LW can see, we have given diagrams of his likely visual fields to support family and our wider team in everyday interventions, such as watching TV or ensuring he can see you when you’re talking to him. 

“Plus we’re currently exploring different methods within his ability to find the easiest/ least energy consuming method for LW and figuring out which will be the most successful technique for staff and family to replicate.”

Never giving up

LW’s family are overjoyed with his progress. They had always felt LW had potential, and the glimmers of hope they saw motivated Kirsty and the team not to give up when the odds were against them.

Kirsty says: “During those first few months, we tried many ways to assess LW and optimise his responses. Lots of our attempts were unsuccessful and we would have to go back to the drawing board. There were times when I did begin to doubt whether or not we would achieve our goals, but I wasn’t going to give up.

“LW always had the potential, we just needed to figure out how to access it. The wish now is that we can build his responses into something more functional for his family and for our team here, all the while focusing on how we can improve his quality of life with what we've found.”

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