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PREP is started within 3 days after a stroke and is a sequence of 3 tests. The first test is all that's required for around half of the patients. PREP predicts a patient's potential for recovery of arm and hand movement. Recovery potential is classified as complete, notable, limited or none.

Algorithm no cases.jpg

You can download a slide show about the PREP algorithm, and how to use it for tailoring upper limb rehabilitation. This slide show is designed as an educational resource for individuals and clinical teams.


PREP: A Three Step Process

The first step of PREP is to establish a patient's SAFE score within 72 hours of stroke. The SAFE score is calculated by asking the patient to perform two standardised movements (Shoulder Abduction and Finger Extension). The patient's strength in each of these movements is scored by the therapist between 0 and 5, where 0 is no movement and 5 is normal strength and movement. You can find more details on the PREP for clinicians page.

The two scores are added to form the SAFE score out of 10.

If the SAFE score ‍‍‍is ≥‍‍‍ 8, patients have potential for complete recovery of hand and arm function.

If the SAFE score is 5, 6 or 7, patients have notable potential for recovery.

If the SAFE score is 5 or more, no further tests are required. So far, we have found that around half of the patients only need the first step of the PREP algorithm, and can be classified using only the SAFE score.

If the SAFE score is ≤ 4, TMS assessment is required before recovery potential can be assessed.


The second step of PREP is to test the functioning of motor pathways between the stroke-affected side of the brain and the affected arm for those with a SAFE score of less than 5. A procedure called TMS (Transcranial Magnetic Stimulation) is used to do this. This is a non-invasive test which takes about 30 minutes and can be done at the patient's bedside.

The TMS is carried out 5 - 7 days after stroke. If the TMS results show functional motor pathways (presence of motor evoked potentials, i.e. MEP+), then patients are classified as having notable recovery potential. So far, we have found that around 25% of patients can be classified after the TMS step.
If the TMS results do not show functional motor pathways (no MEP), then an MRI scan is needed.

The third step of PREP is an MRI scan (Magnetic Resonance Imaging) carried out 10 - 14 days after stroke. The MRI scan takes around 30 minutes and is used to look at the anatomical structure of the motor pathways on each side of the brain. We use a type of MRI called Diffusion-weighted imaging to establish the fractional anisotropy asymmetry index (see article).
  • If the asymmetry index ‍‍‍‍‍< 0.15,‍‍‍‍‍ patients are predicted to have limited potential for upper limb recovery.
  • If the asymmetry index ≥ 0.15, patients are predicted to have recovery potential of none.


Using PREP to Focus Rehabilitation

The focus of rehabilitation depends on the patient's predicted potential for recovery of hand and arm function. You can download resources outlining the recommended rehabilitation focus for patients and clinicians.

Complete
The patient has the potential to make a complete, or near complete, recovery in their arm and hand within 12 weeks. Carrying out a prescribed programme of self-directed arm and hand exercise gives the patient about a 90% chance of reaching this potential.
The rehabilitation focus is to Promote Normal Use.

Notable
Patients have the potential to be using their arm and hand in most day to day activities within 12 weeks.
Arm and hand rehabilitation should focus on improving function by increasing strength, coordination and fine control. Repetitive practice of movement and everyday tasks should help. The affected arm and hand should be used for safe daily activities and compensation with the stronger arm should be minimised.
The rehabilitation focus is to Promote Function.

Limited
Patients have the potential to have some movement in their arm and hand within 12 weeks. However, activities that use their affected arm and hand are likely to require some modification.
Arm and hand rehabilitation should focus on maintaining and improving the strength and flexibility of the affected arm and hand, and helping to adapt day to day activities to incorporate this arm and hand wherever possible.
The rehabilitation focus is to Promote Movement.

None
Patients have the potential to gain minimal movement in their affected hand and arm within 12 weeks.
Arm and hand rehabilitation should focus on prevention of secondary complications, such as pain and tightness, and helping the patient to do everyday activities with the stronger arm and hand.
The rehabilitation focus is to Promote Compensation.


For more information about what is done with the results of the PREP algorithm, please see the Resources page.

If you have any further questions regarding PREP, feel free to contact the PREP team, or simply send us an email at prep@auckland.ac.nz


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