A critical time window for recovery extends beyond one-year post-stroke

Abstract

The impact of rehabilitation on post-stroke motor recovery and its dependency on the patient’s chronicity remain unclear. The field has widely accepted the notion of a proportional recovery rule with a “critical window for recovery” within the first 3–6 mo poststroke. This hypothesis justifies the general cessation of physical therapy at chronic stages. However, the limits of this critical window have, so far, been poorly defined. In this analysis, we address this question, and we further explore the temporal structure of motor recovery using individual patient data from a homogeneous sample of 219 individuals with mild to moderate upper-limb hemiparesis. We observed that improvement in body function and structure was possible even at late chronic stages. A bootstrapping analysis revealed a gradient of enhanced sensitivity to treatment that extended beyond 12 mo poststroke. Clinical guidelines for rehabilitation should be revised in the context of this temporal structure. NEW & NOTEWORTHY Previous studies in humans suggest that there is a 3- to 6-mo “critical window” of heightened neuroplasticity poststroke. We analyze the temporal structure of recovery in patients with hemiparesis and uncover a precise gradient of enhanced sensitivity to treatment that expands far beyond the limits of the so-called critical window. These findings highlight the need for providing therapy to patients at the chronic and late chronic stages.

Available Therapeutics after a Stroke: Current and Promising Options

“…Post-stroke physical rehabilitation (PR) is of utmost importance as a nonpharmacological strategy for neuroprotection and neurorestoration but, most significantly, should be aimed at restoring and regaining motor impairment during the chronic period [90], and to promote the functional autonomy of the patient [4]. Recovery of body function assessment depends on whether the patients can perform everyday activities on their own and is measurable by several different scales such as UE-FM score for the upper extremity, and the Barthel Index for Activities for Daily Living scale [4].…”

“…Some clinical parameters that can be observed at the bedside, such as early finger extension and shoulder abduction, can act as predictors of long-term (over 6 months) recovery after stroke [93]. Spontaneous recovery of upper and lower limbs occurs depending on the type, location, and severity of the lesion, in approximately 60-70% of cases [93] during the first 2-6 months [4,94], period after which most people believe they have achieved maximal recovery and stop with either physical or pharmacological therapy [4,95]. Interventions should be designed according to the stage of neurological recovery the patient is in, with the consideration that early chronicity is not a contraindication for continuing rehabilitation [4].…”

“…Physical rehabilitation must start early, if possible, during the first week poststroke [96], because there is an intensification in neuroplasticity during the early stages [91], employing different mechanisms such as the axon regeneration [88], and the higher expression of growth-promoting genes, such as GAP-43. This lesioninduced plasticity that happens during the first days post-stroke [90,97,98] reportedly lasts around 6 months after stroke [4,91,95,97]. Also, therapy must continue after such a period, to take advantage of behavior-induced plasticity [95], which is still possible after 1 year of having had the stroke [4].…”

“…This lesioninduced plasticity that happens during the first days post-stroke [90,97,98] reportedly lasts around 6 months after stroke [4,91,95,97]. Also, therapy must continue after such a period, to take advantage of behavior-induced plasticity [95], which is still possible after 1 year of having had the stroke [4].…”

“…Motor deficits after stroke account for the high rates of longlasting disability. The most common impairments are related to speech, or language and communication disorders (aphasia and dysphasia), apraxia [4], swallowing, depression, cognitive impairment, and hemiparesis of the contralateral limb [5] characterized by muscle weakness or spasticity in distal rather than proximal muscles [6]. These deficits ultimately cause chronic disability, affecting the ability to work and the patient's independence and autonomy for performing daily life activities such as dressing or eating, ensuring they will require long-lasting care, which also deteriorates their quality of life and that of the patients' caregivers.…”