Severe brain injury is a catastrophic event rendering a person unconscious; some survivors will remain unconscious for prolonged periods of time, posing many challenges for medical rehabilitation professionals providing services. For speech-language pathologists, the challenge is to develop meaningful treatment plans and goals. The swallowing modality should be one component of the SLP's treatment plan. However, swallowing is often disregarded as a plausible intervention modality because of aspiration-related risks. SLPs play an important role in evaluating the cognitive status of this population in relationship to swallowing, and it is critical that clinicians understand how to provide safe swallowing treatments for persons in states of prolonged disordered consciousness.
For persons surviving a severe acquired brain injury (ABI), there are two dimensions of recovery—consciousness and function. Although no definition of consciousness is universally accepted (Overgaard, 2009), clinical consensus guidelines define states of disordered consciousness. The consensus guidelines identify three states of disordered consciousness—coma, vegetative, and minimally conscious—and suggest clinical criteria for emergence from minimal consciousness. The clinical consensus criteria defining these states are less controversial given recent refinements of bedside assessment tools, but the lack of a gold standard for diagnosing these states remains problematic (Giacino et al., 2009).
Differentiation among states of disordered consciousness is important because swallowing difficulties after severe ABI relate to the cognitive as well as the physiological impairments of the swallowing mechanism. The following indications are listed in the clinical consensus guidelines (Giacino et al., 2006; Multi-Society Task Force on PVS, 1994):
- Emergence from coma is signaled by opening the eyes.
- The vegetative state (VS) is indicated by wakefulness without internal or external awareness (i.e., self and environment).
- Minimal consciousness state (MCS) is the ability to demonstrate limited but clear evidence of awareness of self and environment, without evidence of functional communication.
The distinguishing characteristic between VS and MCS is the demonstration of at least one clear-cut behavioral sign of consciousness. However, the definition is unclear about what type of evidence (e.g., consistency, smiling in response to a joke) is sufficient to demonstrate clearly that a specific behavior is purposeful and indicates clear internal and external awareness (Giacino et al., 2009).
Diagnosis of these three states of altered consciousness requires clinical examinations that allow clinicians to infer the level of cognitive function from observed behaviors. The elicited behavioral responses are usually limited in complexity and consistency. Variations in arousal levels confound interpretations related to consistency of observed behaviors. In addition, it is often difficult to distinguish between reflexive involuntary movements and purposeful behaviors, and sensory and/or motor deficits may cause a clinician to underestimate a patient's cognitive abilities (Seel et al., 2010). Accurate assessment of level of consciousness may be hindered if patients are improperly positioned or uncomfortable, or if patients are cortically blind, deaf, and/or aphasic. These challenges, as well as others, contribute to diagnostic inaccuracies. In the absence of "hard" neurophysiologic markers (i.e., no neurological tests, such as a functional MRI, can definitively diagnose between the various levels of consciousness), behavioral assessments remain the best way to determine a patient's level of consciousness (Giacino et al., 2009; Seel et al., 2010).
Role of the SLP
The first step for an SLP involved in the clinical management of persons with disordered consciousness is the accurate measure of cognitive functioning. The ability to identify fluctuating levels of consciousness and cognitive functioning has important implications for the patient's overall prognosis and treatment (Seel et al., 2010). The Ranchos Los Amigos (RLA) levels of cognitive functioning describe states of consciousness. RLA Levels I–III describe the recovery of consciousness in behavioral terms: RLA I correlates to coma, RLA II to vegetative state, and RLA III to the minimally conscious state. RLA IV and above describe the various stages of cognitive recovery following the return of consciousness.
In addition to the RLA descriptive levels, SLPs can perform bedside tests, including the Disorders of Consciousness Scale (DOCS). The DOCS enables clinicians to measure with accuracy the levels of fluctuating cognition for patients in states of disordered consciousness. Its eight subscales include "Taste & Swallowing," which evaluates patient response to pre-swallowing stimulation as well as the ability to swallow within 15–20 seconds of stimulation. Table 1 [PDF] outlines the test items for this subscale and the corresponding neuroanatomical level for each DOCS test item.
The DOCS manual and testing forms are available free in the public domain. The manual includes information on the development and psychometric properties of the test, instructions on how to build a testing kit, and copies of conversion charts and testing forms. (To request the DOCS manual and the training DVD, e-mail email@example.com; a nominal charge covers the cost of copying the DVD.)
The DOCS taste and swallowing test items do not involve providing an actual bolus to the patient, but the test-item responses give the clinician important baseline information regarding pre-swallowing and swallowing abilities, level of cognitive functioning, and level of consciousness. Because post-ABI swallowing difficulties are common, clinicians must be cautious in starting therapeutic oral feedings with this population. The baseline DOCS information can guide the SLP in determining if the patient with disordered consciousness is a candidate for an advanced swallowing evaluation.
Given the limited information available in the literature regarding the safety and efficacy of providing swallowing assessment and treatment to this patient population, our facility conducted research with patients admitted for acute rehabilitation to understand more clearly the risk/benefit of this specific treatment modality (Brady, Pape, Darragh, Escobar, & Rao, 2009; Brady et al., 2006).
We investigated the feasibility, safety, and potential benefits of conducting either a videofluoroscopic swallow study (VFSS) or a fiberoptic endoscopic exam of the swallow (FEES) for patients in states of disordered consciousness (RLA I–III), and examined the safety and efficacy of providing oral feedings to individuals early in coma recovery. The age range was 19–82 years. Results demonstrated that the majority of patients (76%) who participated in either a VFSS or FEES while still functioning in an MCS were able to participate successfully in the examination and to advance to therapeutic feedings following the swallowing test.
Results regarding aspiration rates were similar between the patients who completed a VFSS or FEES while in an MCS and those patients for whom swallowing examinations were deferred until they regained full consciousness (41% vs. 39%, respectively). The results also revealed that safe therapeutic oral feeding was possible with patients who were functioning in an MCS, in accordance with the findings from the instrumental swallowing examination. The majority of patients (85%) who were functioning in an MCS and advanced to therapeutic feedings according to VFSS or FEES findings also demonstrated no adverse medical complications.
Pulmonary medical complications for the other patients were determined to be unrelated to therapeutic oral feedings, as those patients had a documented episode of aspiration of gastric tube feeding content within the 24 hours prior to their emergency discharge. All of the patients in this study had G-tube feeding (no NG tubes). In a final important finding, the research showed that provision of swallowing evaluations and swallowing treatment did not significantly increase the cost of acute rehabilitation.
Taste stimulation, rather than therapeutic oral feedings, has historically been advocated for patients functioning at MCS. In this procedure, an amount of food too small to pose an aspiration risk is placed in a specific area of the oral cavity. Taste stimulation is an important first step in evaluating the patient's ability to accept food/liquid and a utensil by mouth and to stimulate swallows. If the patient in MCS is able to accept food/liquid or a spoon into the mouth, the SLP should consider conducting a VFSS or FEES to determine if the patient is ready to advance to therapeutic oral feedings.
In contrast to taste stimulation, therapeutic oral feedings provide the patient with small, controlled amounts of food or liquid in an actual bolus size ranging from 1 to 5 ml, which, if aspirated, could have pulmonary consequences. Although therapeutic feedings initiated early in coma recovery (i.e., MCS) are not sufficient to meet nutritional needs, the potential impact on long-term outcomes and the quality of life should not be discounted. Although the influence of therapeutic feedings early in coma recovery on long-term outcomes is unknown, the provision of a meaningful intervention such as swallowing small amounts of food may help the patient's recovery and may help the family's adjustment. Previous research has shown improved family adjustment with the achievement of a tangible goal or meaningful activity (Wade, Michaud, & Brown, 2006).
Safety is the main concern in providing therapeutic oral feedings with persons in an MCS. A strong bite response and periods of increased lethargy may make it difficult to conduct evaluations and administer therapeutic oral feedings safely. Other obstacles may limit the SLP's ability to conduct a safe VFSS or FEES. If either test indicates that an MCS patient can receive therapeutic oral feedings, the SLP must be aware of the specific circumstances of each MCS patient to ensure the safe provision of therapeutic oral feedings. A patient's readiness for swallowing treatment may be highly variable, changing from day to day—even within a session. The level of swallowing intervention (e.g., taste stimulation versus therapeutic oral feedings) should be determined according to each MCS patient's particular situation.
Research demonstrates the feasibility of conducting an instrumental assessment of the swallow, or FEES, with minimally conscious patients (Brady et al., 2009; Brady et al., 2006). To provide appropriate swallowing interventions, SLPs need to be able to identify a patient's level of consciousness, cognitive functioning, and unique swallowing challenges. Bedside behavioral tests such as the DOCS may assist in achieving these goals. Additionally, therapeutic oral feedings following a VFSS or FEES were shown to be safe in our study, with the majority of patients functioning in MCS demonstrating no adverse medical complications. The research also showed that swallowing assessments and swallowing interventions do not significantly increase the overall cost of patient care. Patients who are recovering from a prolonged disordered consciousness, however, may exhibit varying levels of performance.
SLPs must maintain constant vigilance to ensure safety with therapeutic oral feedings. Instrumental swallow evaluations should be considered as one modality for the overall sensory stimulation and retraining program for patients with disordered consciousness, as these evaluations do not increase costs and may lead to recommendations for therapeutic oral feedings.