Dysphagia post acquired brain injury (ABI) has been attributed to pharyngeal muscular dysfunction and lack of coordination secondary to central nervous system loss of control. The reported incidence of dysphagia among individuals with brain injury varies considerably, due in part to differences in the timing and method of assessment and the initial level of severity. Although the incidence of dysphagia is can be high following ABI, swallowing function most frequently improves over time.
As previously noted rates of dysphagia are variable, with the literature ranging between 26% and 70% (Cherney & Halper 1996; Cherney & Halper 1989; Field & Weiss 1989; Halper et al. 1999; Mackay et al. 1999b; Schurr et al. 1999; Winstein 1983). When specifically examining the rates at rehabilitation centres, the rates range from 26% to 42% (Cherney & Halper 1996; Cherney & Halper 1989; Field & Weiss 1989; Winstein 1983). Many of these rates are determined at admission; however, Winstein (1983) reported that by time of discharge, 84% of those patients admitted with swallowing problems were eating oral feeds. At follow-up, in the outpatient clinic, this number increased to 94%. The most common swallowing problems among patients with ABI included prolonged oral transit (87.5%), delayed swallow reflex (87.5%), valleculae pooling (62.5%), and pyriform sinus pooling (62.5%; Field & Weiss, 1989). In the study by Mackay et al. (1999b) other swallowing abnormalities included loss of bolus control (79%), reduced lingual control (79%), and decreased tongue base retraction (61%) delayed trigger of swallowing reflex (48%), reduced laryngeal closure (45%), reduced laryngeal elevation (36%), unilateral pharyngeal paralysis (24%), absent swallow reflex (6%) and cricopharyngeal dysfunction (3%). For these studies, the most common factor impacting swallowing problems was cognitive functioning (Mackay et al. 1999b; Winstein 1983).
The incidence of dysphagia in patients post ABI ranges from 26% to 70%. More specifically, the range was between 26% and 42% for individuals entering a rehabilitation facility.
The incidence of dysphagia has been shown to vary depending on the definition of dysphagia used and the acuity of the patient at admission.
Risk Factors for dysphagia post abi
Typically the more severe the brain injury, the more severe the swallowing problem (Logemann 2013); however, the relationship between injury severity/ characteristics and the nature of the swallowing disorder needs to be further researched. Within the literature, many researchers have attempted to identify the factors that may affect the presence and severity of dysphagia post ABI (Cherney & Halper 1996; Halper et al. 1999; Mackay et al. 1999a; Mackay et al. 1999b; Morgan & Mackay 1999).
For example, injuries that result from translaryngeal intubation or tracheostomy may contribute to swallowing dysfunction in ABI patients (Morgan & Mackay 1999).
Table: Risk Factors for Dysphagia Post ABI