Natural history and pattern of recovery. Observational studies have provided insight into the natural history of recovery from an acquired brain injury. It is generally believed that the first few weeks postinjury, the so-called acute-subacute period, is the time frame for the greatest rate of spontaneous recovery.
Although a great amount of recovery is experienced initially, most survivors who do not achieve early and complete recovery eventually reach a plateau phase without additional significant spontaneous improvement. In the Copenhagen Stroke Study, a cohort study of over 1100 patients hospitalized with acute stroke found maximum arm motor function within 9 weeks poststroke in 95% of patients. Among those with lower extremity paresis, recovery of walking function occurred in 95% of the patients within the first 11 weeks after stroke (28). The time and the degree of recovery were associated with the degree of functional walking impairment and the severity of lower extremity paresis. In a longitudinal study of patients with long COVID and neurologic symptoms, only one third demonstrated complete resolution of symptoms at 6 months, but most showed improvement in cognition (39). A study also showed that most stroke survivors (with exception of patients with initial severe disability) can recover about 70% of their maximal recovery potential (37). This “70% rule” has been replicated in multiple studies. Similar findings have been observed in patients with aphasia or neglect, with recovery plateaus occurring at approximately 6 weeks and 3 months, respectively (24).
General patterns are also seen with respect to rate of recovery among various types of deficits. For motor deficits, proximal recovery usually occurs before distal recovery, and lower extremity deficits have faster recovery in terms of disability measures when compared to upper extremity deficits. Swallowing, facial movement, and gait tend to demonstrate better recovery. Eloquent cortical functions, such as language, dominant hand movement, and spatial attention, are more lateralized in function and recover more slowly (10).
Predictors of recovery and prognostic factors. A common question or issue posed by patients and their families relates to recovery from and prognosis after injury. Similar to other diseases, there are multiple contributing factors that affect overall prognostication. The initial injury serves as an important prognostic factor for subsequent stroke recovery. As an example, the more severe the initial injury as defined by motor function, the more impairment patients will experience in the chronic phase (16). Comorbidities, such as diabetes, degree of periventricular white matter disease, prior stroke, etc., can adversely affect the stroke outcomes (19; 26). Depression is another comorbidity that can occur after a CNS injury; the interaction between poststroke depression and neurorecovery is complex, but studies have demonstrated that depression can impede rehabilitation and jeopardize quality of life.
Although some studies have shown that increased age is a significant prognostic factor for poorer outcomes (31), others have reported different views (03). Socioeconomic status (insurance coverage, educational level, household income, etc.) is tied with access issues and subsequent recovery outcomes. The relative or complete lack of health insurance coverage may delay or limit access to rehabilitative services. Genetic variation may account for some of the inter-individual variability in recovery. Of these gene candidates, brain-derived neurotrophic factor (BDNF) is the most widely investigated. Studies have shown that it plays a major role in synaptic plasticity as well as in learning and memory, thereby possibly affecting stroke recovery (35). In a study of patients with progressive multiple sclerosis, those with the BDNF Val66Met genetic polymorphism were associated with walking function improvement after rehabilitation (21).
For stroke patients, recovery of the upper and lower extremities can be predicted through an algorithm dubbed the PREP2 algorithm. This algorithm uses clinical exam findings of shoulder abduction, finger extension in combination with the presence of motor-evoked potentials, patient age, and stroke severity as measured by the NIH Stroke Scale (NIHSS) to predict recovery within the 1 to 7 days after stroke (41). Algorithms are useful in counseling patients and their families about setting realistic expectations, receiving appropriate rehabilitation, and planning for further rehabilitation. Similar algorithms can help with other stroke disciplines.
Sites for rehabilitation. The goal of neurorehabilitation should be to facilitate relearning of skills that were possible before the brain injury, but in some cases, the focus of rehabilitation must be adaptation and compensation for deficits. This process begins while the patient is hospitalized for stroke and involves motor-skill retraining, preventing complications, and teaching adaptive techniques using a comprehensive approach. In the United States health care system, patients in need of further neurorehabilitation following acute hospitalization have three possible posthospital dispositions: (1) home with outpatient therapy, (2) home with home health therapy, or (3) inpatient rehabilitation facility or skilled nursing facility placement. The disposition is based on the nature and severity of deficits, comorbidities, and insurance or reimbursement options.
Much of the current rehabilitation involves face-to-face contact with a therapist or healthcare professional. However, this may be a limitation for people whose health or stroke severity limits their ability to meet with therapists. Furthermore, patients who live in rural areas may also be unable to access proper rehabilitation services based on distance. With improvements in technology, telemedicine is an option. In fact, a home-based telerehabilitation program demonstrated an equal benefit compared to traditional in-clinic rehabilitation (11).
Rehabilitation team members. Rehabilitation is provided in a team-based approach and involves various disciplines, such as physical therapy, occupational therapy, and speech and language therapy. The role of the team involves setting goals, reevaluating these goals on a regular basis, and making adjustments to the rehabilitation plan as needed. In addition to improving the patient’s function, caregiver training is an important aspect of rehabilitation.
Physical therapists perform evaluations to detect problems with movement and balance. They work with the patient and the rehabilitation team to perform exercises to strengthen muscles for walking, standing, and other activities. Occupational therapists help brain injury survivors learn strategies to manage daily activities, such as eating, bathing, dressing, writing, and cooking. Speech and language pathologists (ie, speech therapists) help brain injury survivors learn strategies to overcome swallowing and language deficits. In the acute setting, they are involved with dysphagia and swallowing evaluations and may make recommendations for alternative methods of oral intake, such as nasogastric tubes or percutaneous endoscopic gastrostomy tubes. In the subacute and outpatient settings, aphasia tends to be the focus of speech and language therapy.
Following the initial evaluation, therapists develop a program and provide exercises that use the principles of neuroplasticity mentioned previously (task specificity, repetition, challenging). The teaching of compensatory and adaptive techniques is another important goal. Therapists train the patient and family in activities such as safe transfers, assisted ambulation, proper feeding, and provision of appropriate adaptive techniques.
Devices and adjunctive therapies. Device-based and adjunctive therapies, such as robotic arms and bodyweight support treadmills, have been proposed; however, studies have failed to demonstrate their superiority over currently used therapies, and evidence to support regular clinical use is lacking (29; 17).
More recently, a device familiar to neurologists but used in a novel way has been shown to improve recovery. Specifically, in the VNS-REHAB study, vagus nerve stimulators when paired with traditional therapy improved motor function in the upper extremity of persons with stroke compared to traditional therapy alone as measured by the Fugl-Meyer Assessment (12). It is important to highlight that the subjects in the study were at least 9 months post-stroke, so well beyond the spontaneous recovery timeline. Noninvasive brain stimulation using transcranial magnetic stimulation or transcranial direct current stimulation induces neuroplasticity by applying an electrical current or magnetic field to induce depolarization in specific areas of the brain. They have been shown, albeit in small studies, to improve motor function in neurologic disorders such as stroke, Parkinson disease, and multiple sclerosis (18). Several nontraditional strategies have demonstrated improved efficacy compared to traditional therapy. Constraint-induced movement therapy is a motor rehabilitation therapy technique in which the unaffected extremity is constrained with a mitt, thereby forcing use of the affected hand. This approach, even in a modified dose using a lower frequency of constraint-induced movement therapy, has been shown to be more effective than standard therapy in the 3- to 9-month poststroke window (46; 33). Melodic intonation therapy has been shown to enhance recovery of poststroke aphasia (44).
Melodic intonation therapy uses musical elements, including melody and rhythm, to improve language production. Spoken language has elements such as intonation, stress, and rhythm, which are referred to as prosody. The theoretical basis of melodic intonation therapy is that language is localized in the dominant hemisphere, but singing and prosody localize to the nondominant hemisphere. In fact, lesions in the nondominant hemisphere can result in aprosody, whereby patients sound monotonous. Consequently, users of melodic intonation therapy take advantage of preserved singing abilities in the unaffected hemisphere and engage language-capable regions in the nondominant (usually right) hemisphere. Although robust evidence for this approach is lacking, it appears that this therapy is most beneficial in stroke survivors with expressive (Broca) aphasia but retained expressive abilities as well as absent bihemispheric damage.
Functional electrostimulation is another technique that can enhance motor recovery in patients with stroke (01; 47). This technique involves applying electrical stimulation to muscles of interest. Functional electrostimulation devices are commercially available, and improving these types of devices is an area of active research interest. The most widely known use for functional electrical stimulation is stimulation of the peroneal nerve to stimulate ankle dorsiflexion, which can be used to treat foot drop. The use of a peroneal nerve functional electrical stimulation device has been found to be as effective in managing foot drop as ankle foot orthosis in patients with chronic stroke (40).
For common sequelae after brain injuries, specific interventions are recommended but require a multidisciplinary approach. For instance, post-stroke pain syndromes can be managed with medications, targeted joint injections with corticosteroids, and psychological approaches, such as biofeedback (13). Another common sequela, spasticity, can be treated with oral medications, botulinum toxin injections, and splinting (07).