Can we predict walking ability after stroke?

Predicting how someone will recover is no easy feat; the way a stroke presents is as individual as we are--and can affect how we walk, eat, speak, and even see. Despite this, the last several decades of research have enabled us to make general predictions for how someone will recover after stroke. Keep in mind: we have seen folks with "poor prognosis" make huge leaps and bounds in their progress! Read below about what major factors impact walking function after a stroke, and how we can maximize recovery, regardless of the prediction.

#1 Where it occurred

Strokes happen in a variety of areas of the brain; however, the usual suspect is the Middle Cerebral Artery (MCA), which can impact the frontal, parietal, and temporal lobes. In an MCA stroke, your brain's ability to generate a signal to tell the muscles what to do can be impaired. If the muscles do not receive a signal from the brain, they can become weakened or develop spasticity. A common condition after an MCA stroke is hemiparesis, or a one-sided weakness of the body. If a stroke occurs in the cerebellum or brain stem, a condition called ataxia can occur, where the brain's decisions about how to move the limbs is not fact-checked by the cerebellum. Many of these conditions can affect one's ability to walk.

Additionally, brain strokes including thalamic strokes can affect strength and walking ability, as many motor pathways originating in the brain pass through the thalamus on the way to the spinal cord.

Figure 1. Side view of the brain, with functional areas highlighted.

#2 Age

While strokes can happen at any age, it is thought that our brain's neuroplasticity may change with age [1]. Neuroplasticity is the brain's ability to change and restructure itself. An example of neuroplasticity is learning a new sport, like Pickleball. The more you practice, the more resources your brain devotes to:

motor pathways, which are the superhighways transmitting information from the brain to the muscles, and
motor plans, kind of like driving directions, for swinging the paddle.

With lots of practice, swinging a paddle is just like driving to your favorite coffee shop, able to be performed with less thought and with increasing levels of skill, adaptable to road bumps along the way. Certain factors work to increase neuroplasticity, including exercising at a high intensities.

#3 Stroke severity

Medical & healthcare professionals use a variety of tests and measures very soon after a stroke occurs to classify the severity of the stroke. One primary measure is the National Institute of Health Stroke Scale (NIHSS), which assesses areas of functioning including consciousness, weakness, perception, speech, and vision, among others [2]. NIHSS scores are like golf scores--the lower the better. The score range is 0-42, where 0 means limited, if any involvement, and 42 is maximal involvement. A score of 25 or higher indicates a "severe" stroke. NIHSS has primarily been used to predict discharge destination after a stay in the hospital, or a stay at an inpatient rehabilitation facility; individuals with severity scores of 14 or greater are more likely to be discharged to a long-term care facility rather than home [3].

#4 Early intervention & assessment

If an individual experiences an ischemic stroke, which occurs as a result of a blood vessel blockage in the brain, brainstem, or spinal cord, there are medical ways to break up the blockage. A physician may prescribe use of a medication called the Tissue Plasminogen Activatior (tPA), aka the "clot buster", within the first few hours of stroke. This medication can break up the clot, allowing blood to flow once more in affected areas of the brain, which for some may improve recovery [4]; however, use of tPA has been shown to increase risk for other conditions, including bleeding of the brain [4].

Assessment early on is also important; many physical assessments performed by physical therapists can be predictive of future outcomes, especially within the first 72 hours of the stroke. Independence with sitting balance and leg strength 72 hours after stroke are both top predictors of future walking ability [5]. Diving deeper into sitting balance, a score of 42/56 or higher on the Function in Sitting Test (FIST), a physical test involving maintaining sitting balance during a variety of reaching and other physical challenges, is a predictor of discharge disposition after inpatient rehabilitation [6].

Additionally, the Functional Independence Measure (FIM) scores that assess how well someone can position themselves in bed, sit or stand, and walk, are also highly predictive of future outcomes. In a meta-analysis, Thorpe et al. (2018) state "For every 1-point increase on the Functional Independence Measure (FIM), a patient is approximately 1.08 times more likely to be discharged home than to institutionalized care" [3].

#5 Prompt rehabilitation

When we should start rehabilitation after a stroke, and what interventions to perform, is a hot topic in stroke rehabilitation. Various "windows of recovery" have been established, citing the first 3-6 months [7], or even year, after a stroke provide the most promise for recovery, and there is some recent physiological evidence to support such a window [8].

While the adage "it's better late than never" rings true for virtually all aspects of rehabilitation, we are learning that physical rehab should ideally begin in the days after stroke to optimize recovery. There are risks to starting rehab too early: in a Cochrane review, very early mobilization (<24 hours of stroke) may not improve outcomes enough to warrant the risk [9]; however, after 24 hours, the consensus is clear. In a recent systematic review, Miranda et al. (2023) found that, excepting the first 24 hours, early mobilization after stroke can improve functional outcomes [10]. In an observational study, individuals post-stroke had better functional outcomes with earlier, more intense therapies [11].

While prompt rehabilitation seems to improve outcomes, improvements in function can be made even if it's been a number of years since the stroke. In a large clinical practice guideline, Hornby et al. (2020) unearthed improvements in walking function for participants performing high intensity training, even after the "golden window" of stroke recovery has passed [12]. While we don't have all the answers yet, research in this area is constantly being done to improve patient outcomes! Stay tuned for more on "high intensity gait training" and other high quality interventions to promote recovery across a wide variety of neurological populations, from acute to chronic!

References

1. Burke SN, Barnes CA. Neural plasticity in the ageing brain. Nat Rev Neurosci. 2006;7(1):30-40. doi:10.1038/nrn1809
2. Brott T, Adams HP Jr, Olinger CP, et al. Measurements of acute cerebral infarction: a clinical examination scale. Stroke. 1989;20(7):864-870. doi:10.1161/01.str.20.7.864
3. Thorpe ER, Garrett KB, Smith AM, Reneker JC, Phillips RS. Outcome Measure Scores Predict Discharge Destination in Patients With Acute and Subacute Stroke: A Systematic Review and Series of Meta-analyses. J Neurol Phys Ther. 2018;42(1):2-11. doi:10.1097/NPT.0000000000000211
4. National Institute of Neurological Disorders and Stroke rt-PA Stroke Study Group. Tissue plasminogen activator for acute ischemic stroke. N Engl J Med. 1995;333(24):1581-1587. doi:10.1056/NEJM199512143332401
5. Veerbeek JM, Van Wegen EE, Harmeling-Van der Wel BC, Kwakkel G; EPOS Investigators. Is accurate prediction of gait in nonambulatory stroke patients possible within 72 hours poststroke? The EPOS study. Neurorehabil Neural Repair. 2011;25(3):268-274. doi:10.1177/1545968310384271
6. Gorman S, Harro CC; Platko C. Function In Sitting Test Admission Score Predicts Inpatient Rehabilitation Discharge Destination. Research poster presentation APTA Academy of Neurology and Academy of Pediatric Physical Therapy; IV Step Conference 2016: Prevention, Prediction, Plasticity, and Participation. Columbus OH, July 16, 2016
7. Langhorne P, Bernhardt J, Kwakkel G. Stroke rehabilitation. Lancet. 2011;377(9778):1693-1702. doi:10.1016/S0140-6736(11)60325-5
8. Hordacre B, Austin D, Brown KE, et al. Evidence for a Window of Enhanced Plasticity in the Human Motor Cortex Following Ischemic Stroke. Neurorehabil Neural Repair. 2021;35(4):307-320. doi:10.1177/1545968321992330
9. Langhorne P, Collier JM, Bate PJ, Thuy MN, Bernhardt J. Very early versus delayed mobilisation after stroke. Cochrane Database Syst Rev. 2018;10(10):CD006187. Published 2018 Oct 16. doi:10.1002/14651858.CD006187.pub3
10. Mariana de Aquino Miranda J, Mendes Borges V, Bazan R, José Luvizutto G, Sabrysna Morais Shinosaki J. Early mobilization in acute stroke phase: a systematic review. Top Stroke Rehabil. 2023;30(2):157-168. doi:10.1080/10749357.2021.2008595
11. Horn SD, DeJong G, Smout RJ, Gassaway J, James R, Conroy B. Stroke rehabilitation patients, practice, and outcomes: is earlier and more aggressive therapy better?. Arch Phys Med Rehabil. 2005;86(12 Suppl 2):S101-S114. doi:10.1016/j.apmr.2005.09.016
12. Hornby TG, Reisman DS, Ward IG, et al. Clinical Practice Guideline to Improve Locomotor Function Following Chronic Stroke, Incomplete Spinal Cord Injury, and Brain Injury. J Neurol Phys Ther. 2020;44(1):49-100. doi:10.1097/NPT.0000000000000303

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