Reduced Maximum Pitch Elevation Predicts Silent Aspiration of Small Liquid Volumes in Stroke Patients

Could be useful is determining when you are in less danger of aspiration. Ask your doctor if they know how to test for this.
http://journal.frontiersin.org/article/10.3389/fneur.2017.00436/full?

Akila Theyyar Rajappa¹, Kristie R. Soriano², Courtney Ziemer², Michelle S. Troche¹, Jaime Bauer Malandraki³ and Georgia A. Malandraki³*

• ¹Department of Biobehavioral Sciences, Teachers College, Columbia University, New York, NY, United States
• ²Department of Speech Pathology and Audiology, JFK Rehabilitation Institute, Edison, NJ, United States
• ³Department of Speech, Language, and Hearing Sciences, Purdue University, West Lafayette, IN, United States

Background and purpose: Preliminary evidence has shown that reduced ability to maximally raise vocal pitch correlates with the occurrence of aspiration (i.e., airway invasion by food or liquid). However, it is unclear if this simple task can be used as a reliable predictor of aspiration in stroke patients. Our aim was to examine whether maximum vocal pitch elevation predicted airway invasion and dysphagia in stroke.

Methods: Forty-five consecutive stroke patients (<1 month poststroke) at a rehabilitation setting participated in a videofluoroscopic swallow study and two maximum vocal pitch elevation tasks. Maximum pitch was evaluated acoustically [maximum fundamental frequency (max F₀)] and perceptually. Swallowing safety was rated using the Penetration/Aspiration Scale and swallowing performance was assessed using components of the Modified Barium Swallow Impairment Profile (MBSImPTM©). Data were analyzed using simple regression and receiver operating characteristics curves to test the sensitivity and specificity of max F₀ in predicting aspiration. Correlations between max F₀ and MBSImP variables were also examined.

Results: Max F₀ predicted silent aspiration of small liquid volumes with 80% sensitivity and 65% specificity (p = 0.023; area under the curve: 0.815; cutoff value of 359.03 Hz). Max F₀ did not predict non-silent aspiration or penetration in this sample and did not significantly correlate with MBSImP variables. Furthermore, all participants who aspirated silently on small liquid volumes (11% of sample) had suffered cortical or subcortical lesions.

Conclusion: In stroke patients (<1 month poststroke), reduced maximum pitch elevation predicts silent aspiration of small liquid volumes with high sensitivity and moderate specificity. Future large-scale studies focusing on further validating this finding and exploring the value of this simple and non-invasive tool as part of a dysphagia screening are warranted.

Introduction

Oropharyngeal dysphagia is seen in more than 50% of patients post stroke (1), with 10–15% of stroke survivors experiencing persistent dysphagia for more than 6 months (2). Importantly, post stroke dysphagia may lead to malnutrition, dehydration, aspiration pneumonia, increased length of hospital stay, reduced quality of life, or death (1, 3). Therefore, early identification of dysphagia in this population is of paramount importance for preventing complications and improving patient outcomes (1).

Current best practice in dysphagia evaluation in stroke predominantly includes nurse-administered screenings (4–7) that then trigger a referral for a comprehensive assessment by a speech-language pathologist (SLP). Subsequently, SLPs perform clinical swallowing evaluations (CSEs) (8, 9) to determine whether an instrumental swallowing assessment [videofluoroscopic swallowing study (VFSS), or flexible endoscopic evaluation of swallowing (FEES)] is warranted. Despite their widespread clinical utility, the sensitivity and specificity of dysphagia screenings remains variable. In addition, intra- and inter-rater reliability for CSEs is relatively low (10, 11). Crucially, the incidence of undetected silent aspiration (i.e., aspiration without a cough response) on CSEs in neurologically impaired patients is reported to be as high as 42% (12), significantly impacting their rehabilitation potential. Thus, the need to identify additional clinical signs of aspiration and dysphagia in stroke is urgent in order to enhance early referral and treatment.

Maximum vocal pitch elevation and swallowing share several anatomical and neurophysiological substrates (13–17). Preliminary evidence has revealed that reduced ability to maximally raise vocal pitch correlates with the occurrence of aspiration (18). Specifically, in a study of 40 patients with dysphagia of variable etiologies, lower maximum pitch elevation measured acoustically and perceptually was associated with more severe airway invasion during swallowing [measured by the Penetration/Aspiration Scale (PAS)] (19). The authors hypothesized that lesions impacting the superior laryngeal nerve (SLN) and/or chronic aspiration resulting in diminished sensation, affected the sensorimotor processes required for both voice and swallowing in their sample. This study aimed to expand these findings (18) by focusing on stroke patients early post stroke (<1 month post) and improving several methodological limitations of the prior study.

Our primary aim was to determine if maximum pitch elevation of the sound /i/ and/or /a/ (measured acoustically and perceptually) predicted aspiration and/or silent aspiration in stroke. Based on prior work in this area (18), we hypothesized that maximum pitch elevation would significantly predict these events. Second, we aimed to determine whether maximum pitch elevation correlated with ratings of laryngeal elevation, anterior hyoid excursion, and pharyngeal residue. We hypothesized that reduced maximum pitch elevation would correlate with more severe ratings of swallowing physiology.

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