https://www.researchgate.net/publication/5889819_On_the_sneeze-reflex_and_its_control
On the sneeze-reflex andits control* Dag Hydén1 and Stig Arlinger2 1 Department of Otorhinolaryngology, University Hospital, SE-58185 Linköping, Sweden 2 Division of TechnicalAudiology, Department of Neuroscience and Locomotion, Linköping University, SE-581 85 Linköping, Sweden
INTRODUCTION Experiments in cats have shown that sneezing can be induced using low intensity electrical current. This study focusses on answering the question whether the sneezing-reflex can also be induced in man through electrical stimulation, whether it is reproducible, and if the response can be abolished pharmacologically? Three healthy males were tested using intranasal stimulation in different parts of the nose using a current from an electric pulse generator. Using currents in the range 2–11 mA, it was possible to induce and reproduce sneezing in the anterior portion of the nose corresponding to the distribution area of the anterior ethmoidal nerve. In one tested subject, local anaesthetics applied to the mucous membranes of the nose abolished the sneezing. Sneeze reflex-reduction may be one way to reduce viral contamination between subjects. Further research could include pharmacological investigations to identify a sneeze-inhibiting substance with small risks for side effects that can be added to common cold nasal sprays. Key-words: electrically-induced sneezing, pharmacological sneezing-control Little is knownabout the nose andits interaction with the nervous system. This is surprising since sneezing, for example,is an important reflex elicited from the nose. Triggering nerve fibres withinthenosetoinduce sneezing is a most effective way for infectious agents, especiallyrhinoviruses, to insure that they travellong distances quicklyand thereby insuring that they infect and survive innewhosts (1). In experiments, sneezing has been inducedin cats using severaldifferent forms of nasal stimulation: application of electrical currents to the anterior ethmoidal nerve (2), mechanical probing or using puffs of air (3), using a vibrator andbyelectrical stimulation to a brainstem area thought to represent a sneezeevoking area located ponto-medullary close to the descending trigeminal nucleus and tract (4).Inability to sneeze has been describedinpatients withWallenberg´s syndrome (Lateral Medullary Syndrome), indicating presence of a sneeze-centre inthe corresponding area in humans (5). In thisstudy wetried to answer thefollowing questions: can sneezing be induced electrically in man as itcanbe in cats,is it reproducible,isthe lowest trigger-level comparable between subjects, and can it be influencedby local anaesthetics? MATERIALS ANDMETHODS Test-subjects were 3 healthymales, 58 (A), 46 (B) and 37(C) years of age, members of the local research team. They were all well informed of the nature of this research, its minimal risksforside effects and they were highly motivated to participate inthestudy. Sixskinelectrodes used as return electrodes were placed symmetrically, twooneach sideofthe nose and twoonthe forehead. Alamina of silicone was placedinthe nose to protect the area on the corresponding level of the interior of thenosefromstimulation. Anelectricpulse generator (Organon DigiStim 111, Organon Technica, Durham, NC, USA) was used as a stimulator with pulse repetition rate set to the range 30-50 Hz. Stimulations were administeredviaan electrode (Bio-LogicTM-EcochGtrode, Biologic Systems Corp, Mundelein, IL, USA) to the mucous membrane on the lateralwall (A, B, C), both anterior and posterior to the area of theconcha inferior and conchamedia. On theseptal area, stimulations (A, C)were given inferiorlyand superiorly,in anterior and posterior positions. Thetipoftheelectrode was formed using a conductive hydrogel. Sneezing was inducedinall three subjects. Thefindings were reproducible after a latency period.Stimulation was presented with theelectrode at rest and not when it was inmotion, since moving theelectrode withinthe nose in itself can cause sneezing. In A, thestimulation caused sneezing at 8 mAboth from the lateralwall (concha inferior) and theseptalwall, most clearlysofromthe anterior part. After spraying 10% Xylocain (lidocain,AstraZeneca)inthe nose, the sneezing-response was abolishedwith agradualincrease of thethreshold.Inthe second subject,(B), sneezing was inducedwhen theelectrode was
Sneeze-reflex 219 placed on theconcha inferior about 3 cm from the nares with a threshold of 2.4 mA.Doubling thecurrentcaused multiple sneezes. More posterior placement of theelectrodecaused a painful sensation, whileamoreanterior position caused the subject pain in his front teeth.InC, sneezing was induced from themiddlepartofthe concha inferior with athreshold at 4 mA.Placement intheanterior area caused sensation from the front teeth.Stimulation of the anterior septal area caused sneezing at 11 mA. Figure 1illustrates these findings. DISCUSSION Sneeze reflex-reduction can beaway to reduce viral contamination between subjects in a population. Further research should include a more precise anatomicalinvestigation on the location and type of sneeze-triggering nervefibres inthe nose. Pharmacological researchisneeded to identify an effective substance that can inhibit sneezing with acceptably small risk for side effects. Such asubstance might beadded to common cold nasal sprays usedduring an upper respiratory infection. A Figure. 1 Diagram illustrating thestimulus current andlocations that induced sneezing inthethree test subjects A, Band C. clinicalinfectious studyshould be done to evaluate whether inhibition of sneezing inanyway causes problems for the individual.The necessary researchisabroad undertaking that involves many specialists in different fieldsofphysiology and medicine andis not a two-man project. CONCLUSION In man,it is possibletoinduce and reproduce sneezing by electrical stimulation inthe anterior part of the nose corresponding to the distribution area of theanterior ethmoidal nerveashas been observedinthecat.The lowest trigger-level is comparable between normal subjects. Local anaesthetic applied to thenoseabolished the sneezing. ACKNOWLEDGEMENTS Thisstudy was supportedby Östergötlands County Council, Sweden. REFERENCES 1.Gwaltney JM Jr. Rhinovirus infection of the normalhuman airway (Review). Am J Resp Crit Care Med.1995;152: 36-39. 2. Batsel HL, Lines J. Neural mechanisms of sneeze. AmJPhysiol. 1975; 229: 770-776. 3. Macron J-M,Wallois F, Duron B. Influence of vagal afferents in the sneeze reflex in cats. Neuroscience letters 1994; 177: 79-82. 4. NonakaS, Unno T, Ohta Y, Mori S. Sneeze-evoking region within the brainstem. BrainRes1990; 511: 265-270. 5. Hersch M. Loss of ability to sneeze in lateral medullary syndrome. Neurology 2000; 54: 520-521. Dag Hydén, MD, PhD Assistant professor Department of Otorhinolaryngology University Hospital SE-581 85 Linköping Sweden Phone: +46-13-222 000 Fax: +46-13-222 504 E-mail: ***@lio.se