Modulation of human swallowing behaviour by thermal and chemical stimulation in health and after brain injury

Abstract

Few data support thermal or chemical stimulation as therapy for neurogenic dysphagia. Our aims were to explore the behavioural effects of thermal (cold) and chemical (citrus) modalities on water swallowing in health (n = 65, mean age 45 years, 44 females) and acute stroke (n = 22, mean age 67 years, eight females). Multiple randomized timed 50-mL swallowing tests were performed for each of four water conditions: (a) room temperature (RT), (b) cold (CD), (c) citrus (CT) and (d) combined cold and citrus (CD + CT). The inter-swallow interval (ISI), swallowing volume velocity (speed), and volume per swallow (capacity) were measured. In health, compared to RT, only CD + CT slowed the speed (12.3 +/- 0.5 vs 10.3 +/- 0.5 mL s(-1), P < 0.03) and decreased the capacity (16.4 +/- 0.9 vs 14.6 +/- 0.7 mL per swallow, P < 0.02) of swallowing. ISI was unaffected, except by CD + CT in healthy young subjects (<60 years) where it was reduced (1.44 +/- 0.02 vs 1.30 +/- 0.02 s, P < 0.02). Despite smaller volumes ingested by stroke patients, CD + CT, compared to RT, again slowed both the speed (3.8 +/- 0.4 vs 4.5 +/- 0.5 mL s(-1), P < 0.03) and capacity (7.6 +/- 0.7 vs 8.5 +/- 0.7 mL per swallow, P < 0.03) of swallowing but had no effect on ISI. We conclude that combined thermal and chemical modification of water consistently alters swallowing behaviour in health and after cerebral injury. These findings have relevance in the management of neurogenic swallowing problems.

The influence of sour taste and cold temperature in pharyngeal transit duration in patients with stroke

“…Such studies showed changes in swallowing activity and a correlation with the findings of our study, as they also involved the taste and temperature receptors (13,19,22,27) .…”

“…Some stimuli, such as taste and temperature, have an influence on swallowing and also on bolus displacement times (5,13) . Kaatzke-McDonald et al (15) suggested the existence of thermo-receptive receptors at the pillars of fauces, which evoke swallowing when stimulated by a cold touch.…”

Effects of Surface Electrical Stimulation Both at Rest and During Swallowing in Chronic Pharyngeal Dysphagia

“…Based on previous use of sensory stimulation in the oral and pharyngeal cavities to augment patients' volitional control of swallowing [3,11], we compared sensory levels of electrical stimulation just above the participants' sensory threshold for detecting a tingling sensation on the skin, and found a significant improvement during swallowing on the NIH-SSS scale but no change on the PenAsp scale (Figure 3). The improvement on the NIH-SSS tended to be related to higher initial scores; that is the more severely affected patients were those who had the greatest improvement with stimulation.…”

Acidic and Neutral Liquid Ingestion in Patients With Gastroesophageal Reflux Disease

“…With the values of ingestion time and the number of swallows, we calculate: (1) interval between swallows -the total time of ingestion divided by the number of swallows; (2) ingestion flow -the total volume ingested (100 mL) divided by the time of ingestion; (3) swallowing volume -the total volume ingested (100 mL) divided by the number of swallows (1,9,13,14) . For statistical evaluation, a linear regression model was used with mixed effects (random and fixed effects).…”

“…The control of swallowing involves a complex interaction between muscles and nerves that coordinates the safe passage of swallowed material from the mouth to the stomach (13) . It is an ongoing process that involves the mouth, pharynx and esophagus, many oral structures, muscles and nerves.…”