Although clinically evident aspiration is common in subjects with dysphagia, a significant proportion may aspirate silently, i.e., without any outward signs of swallowing difficulty. This article reviews the literature on the prevalence, etiology, and prognostic significance of silent aspiration. An electronic database search was performed using silent aspiration, aspiration, dysphagia, and stroke as search terms, together with hand-searching of articles. Silent aspiration has been described in many conditions and subgroups of patients (including normal individuals), using a number of detection methods, making comparisons a challenge. The best data are for acute stroke, in which 2%-25% of patients may aspirate silently. Mechanisms associated with silent aspiration may include central or local weakness/incoordination of the pharyngeal musculature, reduced laryngopharyngeal sensation, impaired ability to produce a reflexive cough, and low substance P or dopamine levels. In terms of prognosis, silent aspiration has been associated with increased morbidity and mortality in many but not all studies. However, some degree of silent aspiration at night may be normal in healthy individuals. The phenomenon of silent aspiration is poorly understood and further research is needed to improve methods of detection and thereby better define its prevalence and prognostic significance.

Silent aspiration: what do we know?

The present study had two purposes. The first was to provide variability data on objectively measured durational parameters of swallowing as accomplished by dysphagic patients secondary to stroke. The second was to examine the short-term effects of thermal application on these same durational measures. The study employed a cross-over design with each dysphagic stroke subject swallowing 10 times in both untreated and treated conditions. Two findings emerged: (1) swallowing durations in the 22 dysphagic stroke subjects were highly variable within and across subjects and have distributions that were nonnormal with nonhomogeneous variances; (2) thermal application reduced duration of stage transition (DST) and total swallow duration (TSD). Implications of these findings are discussed.

Thermal application reduces the duration of stage transition in dysphagia after stroke

Background

The relationship between subjective complaints of dysphagia and objective measures of swallow function in patients with cancers of the oral cavity, pharynx, or larynx, treated with radiotherapy ± chemotherapy has not been well documented in the literature.



Methods

Swallowing function in 132 patients with various lesions was evaluated using videofluoroscopy and analyzed by patient complaint of dysphagia grouping.



Results

Patients with complaints of dysphagia demonstrated significantly worse swallow function as indicated by lower oropharyngeal swallow efficiency (OPSE), longer transit times, larger residues, and more swallows with aspiration. Patients with complaints of dysphagia also tended to take less of their nutrition by mouth and less variety of food consistencies in their diet compared with those without complaint.



Conclusions

Patients were able to perceive decrements in their swallowing function as dysphagia and may have limited their oral intake in response to that perception. The ability to accurately perceive swallowing function may be useful for self-monitoring changes in dysphagia status during a course of swallow therapy. © 2002 Wiley Periodicals, Inc. Head Neck 24: 555–565, 2002

Swallow function and perception of dysphagia in patients with head and neck cancer

Aspiration is a common problem following stroke, resulting in feeding difficulties and aspiration pneumonia. Despite past studies using clinical assessments and computed tomographic (CT) scans of the head, the correlation of stroke location with aspiration remains unclear. Since brain magnetic resonance imaging is more sensitive than CT for many stroke types, we have correlated MRI lesions with aspiration in patients who have sustained a stroke. We selected patients with acute stroke who underwent brain MRI and a swallowing evaluation. Aspiration was present in 21 of 38 patients (55%). Patients with just small vessel infarcts had a significantly lower occurrence of aspiration (3 of 14, 21%) compared to those with both large- and small-vessel infarcts (15 of 20, 75%, p = 0.002). Multivariate analysis of several specific brain areas failed to identify a significant association between stroke location and the occurrence of aspiration. These findings suggest that patients who have experienced stroke should be individually evaluated for swallowing dysfunction regardless of stroke location or size, since even small-vessel strokes can be associated with aspiration in greater than 20% of cases.

Aspiration after stroke: lesion analysis by brain MRI.

The presence of an endotracheal or tracheostomy tube disrupts the overlaid laryngeal functions of phonation and swallowing. Clinical experience has repeatedly shown that removal of the endotracheal or tracheostomy tube does not automatically restore normal laryngeal functioning. Hoarseness and transglottic aspiration are two frequently encountered pathological responses to endotracheal intubation and tracheostomy. An unprotected glottis is vulnerable to aspiration of secretions and colonized oral flora, enteral feedings, and gastric contents as well as food and liquids. Pulmonary aspiration has the potential of developing into pneumonia, a pathophysiological response that clinicians make every effort to avoid, especially in medically fragile patients.

Evaluation and treatment of swallowing disorders following endotracheal intubation and tracheostomy.

This paper reports the frequency of glucose-6-phosphate dehydrogenase (G6PD) deficiency in the male and female population of Al-Ula in the northwestern province of Saudi Arabia. The frequency of G6PD

M.A.F. El-Hazmi

Papers

Glucose-6-Phosphate Dehydrogenase Deficiency in Saudi Arabia