January 10th, 2018
The Effectiveness of Proprioceptive Neuromuscular Facilitation (PNF) Approach for Adults after a Stroke
Proprioceptive neuromuscular facilitation (PNF) is one of the practices in common application for post-stroke rehabilitation. It is aimed at increasing the strength and stretch of the affected muscle regions thus increase the range of movement (ROM) and facilitate recovery of some of the functionality of the affected regions. Despite its use, only equivocal evidence exists regarding its efficacy. The current paper evaluates literature retrieved from online databases to identify the effectiveness of PNF in treatment after stroke. The review indicates that PNF effects are mainly in enhancing ROM, but it bears no significant advantages over traditional and other physiotherapeutic approaches in clinical practice. However, treatment approaches combining PNF with other approaches such as functional electrical stimulation and Butler’s neuromobilizations may offer a higher efficacy.
Keywords. Proprioceptive Neuromuscular Facilitation (PNF), Stroke, Physiotherapy
The clamor to adopt evidence-informed practices in clinical practice has necessitated the evaluation of the effectiveness of practices that predominate in such settings. In this regard, the practice of physiotherapy is argued to rely heavily on therapists’ beliefs rather than scientific evidence to inform its therapeutic approaches (Westwater-Wood et al. 2010). For instance, physiotherapeutic approaches employed in the treatment after stroke vary widely among therapists thus could result into significant differences in treatment outcomes (Pollock et al. 2008). Such approaches have ranged from those based on orthopedic tenets, through those that employ neurophysiological principles (e.g. Bobath approach and Proprioceptive Neuromuscular Facilitation; PNF) to those that are informed on motor-learning concepts (e.g. sensory integration) (Pollock et al. 2008; Pollock et al. 2007; Chen & Shaw 2006).
The Bobath approach may still be the most predominant approach in Western world (Davidson & Waters 2000; Natarajan et al. 2008), but there lacks adequate evidence to support its superiority over other approaches (Ernst 1990). Similarly, it requires advanced and costly training and years of practice to master its skill-requirements (Davidson & Waters 2000), thus may not solve the need to “select therapies that are most cost-effective and that can be given to the largest number of patients” as advised by Ernst (1990, p.1081). Accordingly, there is a need to evaluate the effectiveness of alternative approaches to identify practices that may help meet such recommendations hence move physiotherapy towards evidence-based practices. This paper thus evaluates the effectiveness of proprioceptive neuromuscular facilitation (PNF), a neurophysiological-informed treatment approach.
PNF traces its antecedent to Dr. Herman Kabat in the 1940s, who proposed it as potential rehabilitation approach (cited in Westwater-Wood 2010, p.23). By definition, PNF refers to the “methods of promoting or hastening the response of the neuromuscular mechanism through stimulation of the proprioceptors” (Voss et al. 1985 as cited in Westwater-Wood 2010, p.23). Proprioceptors are sensors present in muscles (e.g. muscle spindles), tendons and joints that help in movement by providing information about joint angle, muscle length and tension (Solomon et al. 2004, p.790). By playing this role, they help one to “perceive the positions of … [ones] arms, legs, head, and other body parts … [and] the orientation of … [ones] body as a whole” (Solomon et al. 2004, p.790). Thus, proprioceptors form critical components determining normal movement, since movement is dependent on appropriate posture and coordinated reciprocal movements of the limbs (Wang 1994).
Applications of PNF are wide-ranging, with its initial use having been in rehabilitation of patients with spasticity and paresis (Sharman et al. 2006). Subsequently, PNF techniques have been used in treatment of varying conditions including conditions that are not of a neurological etiology such as shoulder and whiplash injuries (Sharman et al. 2006). PNF approaches essentially aim to develop strength and stretch; for strength, the aim is to restore or establish functional muscle contraction whereas for stretch, the objective is to increase the range of motion (ROM) (Sheard 2010). Its underlying theoretical bases are that the neuromuscular components of the body are plastic – achieving either positive changes, as is the case of sports, or negative changes, for instance in muscle imbalance – and that functional movements take place in spiral patterns (Westwater-Wood 2010). Its techniques include isometric activity that improves ROM or reduces pain by mobilizing muscle groups, and handling techniques that improve muscle group’s stability and coordination (Westwater-Wood 2010). When such activities are performed, it is hypothesized that they enhance “afferent proprioceptive discharges into the CNS [resulting into] increased excitation and recruitment of additional motor units” (Pollock et al. 2007, p.5). PNF basis of action thus lie on such hypotheses as (a) the control of movements rests on the brain rather than muscles, (b) sensory stimulation leads to re-organization of movement patterns and (c) abnormal movement patterns result from the failure of inhibitory regulation by higher centers (Richards & Olney 1996).
Despite these theoretical underpinnings, literature regarding PNF’s effectiveness is equivocal. For instance, comparing PNF to Bobath and conventional treatment involving traditional exercises and functional activities, Dickstein et al. (1986) did not find any of the approaches to have significant advantage over the others. Such an observation is reinforced by a review that contends the lack of an identifiable optimal physiotherapeutic approach for treatment after stroke (Ernst 1990). Other studies, however report a beneficial effect of PNF especially following repeated treatments (Wang 1994), while a recent study identifies PNF-based approaches to have an advantage over traditional approaches in reducing spasticity (Wolny et al. 2011). This paper thus assesses the evidence on the effectiveness of PNF as presented in various literature, thus elucidate its appropriateness for application in clinical practice.
Go to part 2 here.