it is a symptom that expresses a disorder in the transport of food and endogenous secretions ( saliva ) through the upper digestive tract . oropharyngeal dysphagia ( od ) is a more anatomically restricted term referred to alterations in the transfer of the bolus from the mouth to the esophagus ( that means , in bolus propelling from the mouth to the pharynx , in the pharyngeal reconfiguration during the swallow , or in the opening of the upper esophageal sphincter ) . od is an inescapable concern in the management of patients with laryngeal and hypopharyngeal cancer . being as a symptom at presentation , as an adverse effect during whatever the treatment , or as sequelae compromising the quality of life of the patients , swallowing disorders have to be adequately anticipated and dealt with . swallowing is one of the vital functions that the larynx is involved in . for an outcome to be considered functional , the patient has to be able to swallow in an effective and safe manner . actually , preserving a functional deglutition is usually the most important goal of the different function - preserving surgical techniques on the larynx and the hypopharynx , as a larynx that does not prevent aspiration even though od has been specifically classified in the latest versions of the international classification of diseases , it has not yet been given the attention it deserves . od is clearly underdiagnosed , and consequently under - treated , in spite of the high rate of complications it entails . although the highest prevalence corresponds to the elderly and patients with neurological disorders , head and neck cancer patients are a population where the disease directly affects the anatomy and function of the structures involved in deglutition . the functional outcome of the patients with laryngeal and hypopharyngeal cancer will ultimately depend upon an accurate diagnosis , treatment , and rehabilitation . to accomplish breathing without a tracheostomy , oral feeding and close to normal phonation may become a difficult challenge . in many cases a function - preserving surgery will not be such without adequate rehabilitation . moreover , chances of function - preserving surgery might be underestimated if a comprehensive swallowing rehabilitation protocol is not available . normal swallowing is a complex series of neuromuscular events which has both reflexive and voluntary controls ( the later making rehabilitation possible ) . although swallowing is a smooth and continuous process , it is conventionally divided into three phases in which timing is controlled by different central pattern generators of the brainstem . the food enters the oral cavity and is mixed with saliva and masticated to form a cohesive bolus . lips , tongue , teeth , mandible , and palate are involved in the preparation and propulsion of the bolus . the pharyngeal phase is initiated when the tongue pushes the bolus towards the posterior pharyngeal wall , eliciting a series of programmed responses : the soft palate elevates to prevent nasal reflux , pharyngeal constrictor muscles contract to push bolus through the pharynx , laryngeal sphincter mechanisms close to prevent aspiration ( epiglottis inverts and true and false vocal folds adduct ) , the larynx is pulled in an anterior and superior direction , and so cricopharyngeal muscle ( upper esophageal sphincter ) is opened . the recent research in the physiology of swallowing has shown that this response can be modulated . the esophageal phase is completely involuntary : peristaltic waves propel the bolus to the stomach . anatomic structures involved in deglutition have a complex motor and sensory innervation by the cranial nerves ( cn ) . the trigeminal nerve ( cn v ) is responsible for the general sensation of the face and for the motor supply to the main muscles involved in mastication . facial nerve ( cn vii ) gives motor function to the lips and taste to the anterior two thirds of the tongue . the glossopharyngeal nerve ( cn ix ) gives general sensation to the posterior third of the tongue and motor supply to the pharyngeal constrictor muscles . the vagus nerve ( cn x ) gives motor function to the soft palate , pharynx , larynx and esophagus , and general sensation to the larynx . this includes the lingual side of the epiglottis , and important sensory site that always triggers deglutition ( a basic mechanism to protect the airway ) . finally , the hypoglossal nerve ( cn xii ) controls most of the muscles involved in tongue motility . od may be caused by anomalies involving the oral cavity , pharynx , and larynx that can be either structural or functional . the site of the primary tumor will determinate symptoms due to alterations of different phases of deglutition , sometimes similar to those that will have to be managed after the treatment . although we focus our interest on the larynx that has certainly a central critical role in deglutition , an isolated discussion on it would be absurd , as patient situation is usually more complex : there are different factors conditioning od , locally advanced tumors will extent to neighboring sites , the neck will have to be treated in many instances , and treatment schemes are usually mixed . in general , lesions in the oral cavity will impair bolus preparation , containment , and posterior movement of the bolus to the pharynx . pharyngeal and laryngeal lesions may show variably altered swallow responses that may condition laryngeal penetration or even tracheal aspiration . the three modalities of treatment used for head and neck malignancies , radiation therapy , chemotherapy , and surgery will have different effects on swallowing that can be additive . external - beam irradiation has early effects due to mucositis that may cause superficial ulceration and pain . fibrosis due to radiation therapy may be expressed as strictures , sometimes requiring dilation or even surgery , muscle changes , and different mechanical changes that will affect deglutition : fixation of the hyolaryngeal complex , reduced tongue motion , and insufficient glottis closure  . there are some methods to prevent or minimize radiation sequelae , like shielding or modified radiation protocols ( like intensity modulation ) . in general , irradiated patients will show reduced oral and pharyngeal functions , with longer transit times , more pharyngeal residue , and reduced cricopharyngeal opening time . actually , postoperative radiation therapy seems to be the main factor influencing worse functional results after partial surgery of the larynx . virtually all of the patients on chemotherapy schemes for head and neck cancer will show some degree of mucositis . it will be clinically significant in up to 40% of the patients and in 100% of those under chemoradiation . on the other hand , patients may have nausea and vomiting along with extreme weakness that might impair swallowing . effects on swallowing caused by surgical treatment are of particular interest because it is precisely the severity of those that will allow the surgery to be considered a function - preserving one . effective and safe swallowing is a requirement for oral alimentation , and so it is one of the main objectives pursued by the different surgical procedures . in general , surgical treatment will alter the structure and function of different anatomical sites in the oral cavity , pharynx , and larynx . in many cases structure can be restored in a close - to - normal anatomic way by different reconstructive procedures . treatment of tumors of the oral cavity will cause a range of predictable problems depending on its location , size , and type of reconstruction performed . the function of the oral ( labial ) sphincter may be affected by local resection or by lesions of the marginal branch of the facial nerve . resections of the floor of the mouth may lead to the loss of the glossoalveolar sulcus or fixation of the tongue . this may cause a variety of problems : they may obstruct bolus passage if they are too bulky , they have no motor function and so there might be a loss of propulsive force , and as they are usually nonsensate flaps , they will lack the normal sensation required to guide the bolus to the oropharynx . tumors affecting the tongue base are probably the ones in this region most prone to cause dysphagia , as tongue base is critical in initiating swallow , propelling the bolus through the pharynx , and obtaining an efficient pharyngeal peristalsis . resections of up to one third of the tongue are well tolerated ; also preserving some neural control ( and thus some movement , at least in one side ) is critical . if the tongue gets fixed to the floor of the mouth or the hypoglossal nerve is damaged , dysphagia will worsen , as it will be difficult to control and direct the bolus inside the mouth , to chew , and to propel the bolus posteriorly . the primary and evolutionarily original function of the larynx is related to the fact that there is an aerodigestive confluence and thus a need for a swallowing act that guides the food in the right direction . the larynx is elevated and moved anteriorly while its sphincters close , thus preventing food to enter the airway . supraglottic laryngectomy will alter some of the sphincter mechanisms of the larynx , and possibly laryngeal excursion during swallowing . in the classic open surgery this late problem ( and partially the former one ) is minimized by laryngeal suspension . transoral laser surgery causes a much smaller damage to the extrinsic mechanism involved in laryngeal movement , and even though the technique does not in any way  suspend in extended procedures involving portions of the tongue base , hyoid bone , and others , swallowing prognosis might be worse . supracricoid laryngectomies , a more aggressive type of partial horizontal laryngectomy , pose problems on the airway ( and thus on the possibility of decannulation ) , on phonation and on swallowing , that may vary depending on every particular case ( figure 1 ) . vertical hemilaryngectomy requires and increased effort for laryngeal adduction and frequently facilitating maneuvers , as one side of the larynx in loss and reconstructed with more or less static structures . patients undergoing total laryngectomy usually do not have significant swallowing problems after surgery ( although they usually do have at diagnosis , so frequently from the patient 's view in this regard function is improved ) . occasionally they may have problems with bolus propelling or strictures in the pharyngeal suture , as well as alterations in the cricopharyngeal sphincter and esophageal motility . it is associated with a rate of morbimortality and impairment in the quality of life . it has a maximum incidence in the elderly , patients with neurological disorders and patients with head and neck cancer . patients in these and other clinical situations may be candidates to be evaluated for swallowing disorders . there is growing evidence that screening for dysphagia is advisable in different groups of patients . a high percentage of patients with head and neck cancer , and virtually all of those with advanced stage tumors , will suffer dysphagia before , during , or after treatment . the assessment of od should include a detailed history focusing on the medical status of the patient , and a comprehensive clinical examination . from the clinical point of view , although the efficiency of oral nutrition might be impaired ( which would lead to malnutrition and dehydration if no alternative route is used ) , it is the possibility of aspiration what focuses the most pressing interest . usually patients with impaired safety of the swallow show cough ( and ultimately aspiration and pneumonia ) , but silent aspiration is not unusual . swallowing trials may be performed on a bedside fashion . the accuracy of the volume - viscosity swallow test for clinical screening of od and aspiration has been demonstrated . it assesses a series of items on the effectiveness and safety of the swallowing in a systematic fashion with different volumes ( 5 , 10 , and 20  ml ) and viscosities ( liquid , nectar , and pudding ) . the main goals of the clinical assessment are screening for the presence of dysphagia , and if so , determining the risk of aspiration and the feasibility of oral nutrition , therefore avoiding the most usual complications , namely , malnutrition and aspiration pneumonia . modifications of the diet , facilitating maneuvers , and other therapeutic measures might be recommended , but if efficiency and safety are not warranted , nonoral nutrition should be advised . finally , dysphagia - related quality of life of the patients can also be assessed by specific questionnaires . virtually every patient with head and neck cancer will show some degree of at least temporary dysphagia that will impact his quality of life . also some conditions associated with the swallowing disorder , like requiring a nasogastric feeding tube , are felt as particularly troublesome for the patients . instrumental assessment of swallowing provides useful information on both the structure and function of the swallowing mechanism , also when anatomy has been changed by the surgical procedure . there are two main diagnostic procedures to be used in the assessment of od . a high - resolution video is used to record a movie that can be later measured and timed on slow motion or static pictures ( figure 2 ) . the modified barium swallow is the technique of choice for the diagnosis of oropharyngeal dysphagia when there is an attributable cause ( as it does happen in head and neck cancer patients ) . the test allows the examiner to observe the interactions between the different swallowing phases and assesses the whole dynamics of the process ( figure 3 ) . a high - resolution video is used to record a movie that can be later measured and timed on slow motion or static pictures ( figure 2 ) . the modified barium swallow is the technique of choice for the diagnosis of oropharyngeal dysphagia when there is an attributable cause ( as it does happen in head and neck cancer patients ) . the test allows the examiner to observe the interactions between the different swallowing phases and assesses the whole dynamics of the process ( figure 3 ) . fiberoptic endoscopic evaluation of swallowingit is a way of directly observing the act of swallowing by means of a flexible endoscope passed through the nose and situated at the nasopharynx facing down towards the hypopharynx . different consistencies and volumes of a colored substance are used for the test . in the swallow test both oral and pharyngeal phases the examination provides particularly complete information on the structure and function of the pharyngeal phase . it can also assess palatal function and the normal movement of the larynx in respiration and phonation . dribble will indicate lip incompetency , and dripping to the hypopharynx will show incompetency of the palatoglossus closure , posing a risk of predeglutition aspiration . when asking the patient to swallow , tongue base movement should be observed to assess propulsion . there might remain residues in the mouth or exist nasopharyngeal reflux if there is nasopharyngeal incompetency . the sequence and synchrony of the movements of the pharyngeal phase should be observed , as well as eventual penetration ( food enters the laryngeal vestibule but remains over the glottic plane ) or aspiration ( there is food in the airway under the vocal folds ) ( figure 4 ) . a sensitivity test can also be performed either with the tip of the endoscope or , ideally , with air pulses . it also gives valuable information on the management of secretions , and it can also be used as a feedback in retraining therapy . it is a way of directly observing the act of swallowing by means of a flexible endoscope passed through the nose and situated at the nasopharynx facing down towards the hypopharynx . different consistencies and volumes of a colored substance are used for the test . in the swallow test both oral and pharyngeal phases the examination provides particularly complete information on the structure and function of the pharyngeal phase . it can also assess palatal function and the normal movement of the larynx in respiration and phonation . dribble will indicate lip incompetency , and dripping to the hypopharynx will show incompetency of the palatoglossus closure , posing a risk of predeglutition aspiration . when asking the patient to swallow , tongue base movement should be observed to assess propulsion . there might remain residues in the mouth or exist nasopharyngeal reflux if there is nasopharyngeal incompetency . the sequence and synchrony of the movements of the pharyngeal phase should be observed , as well as eventual penetration ( food enters the laryngeal vestibule but remains over the glottic plane ) or aspiration ( there is food in the airway under the vocal folds ) ( figure 4 ) . a sensitivity test can also be performed either with the tip of the endoscope or , ideally , with air pulses . it also gives valuable information on the management of secretions , and it can also be used as a feedback in retraining therapy . a number of other procedures can provide additional information on selected cases : other endoscopic procedures like conventional upper digestive tract endoscopy or transnasal esophagoscopy , esophagic manometry , 24-hour ph - metry  . historically , the systematic therapeutic approach to patients with od was first attempted by speech pathologist , as they realized that they could not treat their patients with cerebral palsy if patients were not able to adequately manage oral secretions . the particular organization and composition of the therapeutic team may differ in every institution although a multidisciplinary team will be required , ideally in specific units devoted to the treatment of dysphagia . most of the swallowing disorders can be improved or solved with an adequate personalized training depending on the patient 's condition . this means that the patient can rely on oral diet and will not have aspiration . patients should be informed before the oncologic treatment on the possibility of dysphagia and on the eventual need for rehabilitation . although dysphagia is a usual symptom at diagnosis ( and depending on the tumor it may improve with the treatment ) , pretreatment counseling on the expected swallowing difficulties will help prepare the patient for rehabilitation . some prophylactic measures may be undertaken . when radiation therapy is to be given , it is useful counseling on oral hygiene , avoidance of alcohol and tobacco , hydration , and artificial saliva when required . chemotherapy - related mucositis would be given a symptomatic treatment , usually in the form or mixtures for mouthwashes . severe mucositis can require hospitalization and intravenous treatment or even modifications of the scheme of treatment . when planning a function - preserving surgery , the surgeon has to make certain that , with the preserved or reconstructed structures , deglutition ( without aspiration ) will be possible with adequate rehabilitation . otherwise , alternative options should be considered . a detailed description of treatment modalities for swallowing impairment is beyond the scope of this paper . there is a wide array of therapeutic medical procedures that will fall in some of the following categories . modifications of the environmentthe patient will need a quiet environment and enough time to eat . different specific instruments to introduce the food in the mouth may be preferable in different situations , including specifically designed ones like the  glossectomy spoon . although supervision is adequate , the patient should be encouraged to self - feeding ( when possible ) . different specific instruments to introduce the food in the mouth may be preferable in different situations , including specifically designed ones like the  glossectomy spoon . although supervision is adequate , the patient should be encouraged to self - feeding ( when possible ) . diet modificationsvolume and consistency of the bolus should be modified according to the findings in the clinical tests . sour bolus has been found to significantly shorten pharyngeal transit time in patients with head and neck cancer . volume and consistency of the bolus should be modified according to the findings in the clinical tests . sour bolus has been found to significantly shorten pharyngeal transit time in patients with head and neck cancer . muscular rehabilitationdifferent physiologic exercises may be advisable , like motion exercises or resistance exercises for the jaw , lips , oral tongue , tongue base , laryngeal elevation , laryngeal closure  . different physiologic exercises may be advisable , like motion exercises or resistance exercises for the jaw , lips , oral tongue , tongue base , laryngeal elevation , laryngeal closure  . a variety of choices are available : thermal stimulation by altering food temperature , tactile stimulation by applying pressure to the tongue , sensory stimuli ( anterior facial arch ) to elicit the oropharyngeal phase , introducing mastication ( when possible)  . a variety of choices are available : thermal stimulation by altering food temperature , tactile stimulation by applying pressure to the tongue , sensory stimuli ( anterior facial arch ) to elicit the oropharyngeal phase , introducing mastication ( when possible)  . they also allow the patient to voluntarily modify the dimensions and relationships of the different anatomic structures . this may be used alone or in combination.chin-to-chest maneuver : holding the chin down against the chest facilitates the contact of the tongue base with the posterior pharyngeal wall . it is advisable whenever there is a delay in the swallowing reflex.head extension : helps nasopharyngeal closure and facilitates oral and pharyngeal transit when there is a deficit in the lip or nasopharyngeal closure , or impaired lingual propulsion . adequately preserved laryngeal closure and elevation are imperative to prevent aspiration during the maneuver.head rotation : to one side helps the bolus pass down through the opposite pyriform sinus and closes a damaged pharynx or a paralyzed larynx.head tilt : makes gravity help the bolus down through the healthy side.lying supine or lateral : minimizes the effect of gravity in the bolus when there is poor voluntary control of the mouth to pharynx passage . they also allow the patient to voluntarily modify the dimensions and relationships of the different anatomic structures . this may be used alone or in combination.chin-to-chest maneuver : holding the chin down against the chest facilitates the contact of the tongue base with the posterior pharyngeal wall . it is advisable whenever there is a delay in the swallowing reflex.head extension : helps nasopharyngeal closure and facilitates oral and pharyngeal transit when there is a deficit in the lip or nasopharyngeal closure , or impaired lingual propulsion . adequately preserved laryngeal closure and elevation are imperative to prevent aspiration during the maneuver.head rotation : to one side helps the bolus pass down through the opposite pyriform sinus and closes a damaged pharynx or a paralyzed larynx.head tilt : makes gravity help the bolus down through the healthy side.lying supine or lateral : minimizes the effect of gravity in the bolus when there is poor voluntary control of the mouth to pharynx passage . chin - to - chest maneuver : holding the chin down against the chest facilitates the contact of the tongue base with the posterior pharyngeal wall . head extension : helps nasopharyngeal closure and facilitates oral and pharyngeal transit when there is a deficit in the lip or nasopharyngeal closure , or impaired lingual propulsion . adequately preserved laryngeal closure and elevation are imperative to prevent aspiration during the maneuver . head rotation : to one side helps the bolus pass down through the opposite pyriform sinus and closes a damaged pharynx or a paralyzed larynx . lying supine or lateral : minimizes the effect of gravity in the bolus when there is poor voluntary control of the mouth to pharynx passage . specific swallowing maneuversswallowing maneuvers are designed to alter the physiology of the swallow.supraglottic swallow : closes the vocal folds before and during the swallow to prevent aspiration . this is obtained by a voluntary apnea before the swallow . a voluntary after - swallowing it is useful when there is weakness in the tongue base or an altered pharyngeal peristalsis . it can be assisted by applying the hand on the patient 's forehead and instructing him to press while swallowing.super-supraglottic swallow : is an it is used when laryngeal closure is deficient.mendelsohn maneuver : enhances anterior - superior displacement of the larynx to facilitate cricopharyngeal opening . it is performed by manual displacement and holding of the larynx , and it is indicated when the normal physiologic excursion is impaired or when deglutition is uncoordinated . it improves the transit of the bolus and reduces residues.masako maneuver : ( tongue holding maneuver by biting it ) facilitates the movement of the tongue base and its contact with the posterior pharyngeal wall.repeated swallow :  dry swallow  reduces residues . swallowing maneuvers are designed to alter the physiology of the swallow.supraglottic swallow : closes the vocal folds before and during the swallow to prevent aspiration . this is obtained by a voluntary apnea before the swallow . a voluntary after - swallowing it is useful when there is weakness in the tongue base or an altered pharyngeal peristalsis . it can be assisted by applying the hand on the patient 's forehead and instructing him to press while swallowing.super-supraglottic swallow : is an it is used when laryngeal closure is deficient.mendelsohn maneuver : enhances anterior - superior displacement of the larynx to facilitate cricopharyngeal opening . it is performed by manual displacement and holding of the larynx , and it is indicated when the normal physiologic excursion is impaired or when deglutition is uncoordinated . it improves the transit of the bolus and reduces residues.masako maneuver : ( tongue holding maneuver by biting it ) facilitates the movement of the tongue base and its contact with the posterior pharyngeal wall.repeated swallow :  dry swallow  reduces residues . supraglottic swallow : closes the vocal folds before and during the swallow to prevent aspiration . this is obtained by a voluntary apnea before the swallow . a voluntary after - swallowing it is useful when there is weakness in the tongue base or an altered pharyngeal peristalsis . it can be assisted by applying the hand on the patient 's forehead and instructing him to press while swallowing . mendelsohn maneuver : enhances anterior - superior displacement of the larynx to facilitate cricopharyngeal opening . it is performed by manual displacement and holding of the larynx , and it is indicated when the normal physiologic excursion is impaired or when deglutition is uncoordinated . masako maneuver : ( tongue holding maneuver by biting it ) facilitates the movement of the tongue base and its contact with the posterior pharyngeal wall . repeated swallow :  dry swallow reduces residues . depending on the surgical procedure , and on the swallowing alterations observed in the clinical evaluation , patients will require a personalized therapeutic program that will include a number of the abovementioned resources ( figures 5 and 6 ) . the first one is the importance of a meticulous care in the technique of the function - preserving surgery , with particular attention in the surgical steps specifically directed to improve or preserve swallowing . there are a number of defined entities with specific surgical treatment like procedures for vocal cord medialization . there are also nutritional concerns in the treatment of patients with head and neck cancer , not only before treatment , but also afterwards . patients with mucositis , xerostomia , dysgeusia , odynophagia , or those on liquid diet might be unable ( or unwilling ) to meet their nutritional requirements . nutritional support will improve functional outcomes and the patient 's sense of wellbeing . finally , if oral nutrition is not possible , an alternative method of enteral nutrition should be offered . when a long - term need is expected , gastrostomy should be the option taken . in this situation the airway needs to be protected ; this may be achieved by a tracheostomy with a cuffed cannula ( although deglutition will be further impaired with this measure ) or by means of laryngeal exclusion ( usually by laryngectomy ) , which would of course destroy the expectations of a functional treatment , but would perhaps save the life of the patient . oropharyngeal dysphagia is a critical concern in any function - preserving surgical procedure in patients with laryngeal and hypopharyngeal cancer . this may be done either by clinical or instrumental methods , depending on every particular situation . swallowing rehabilitation is imperative in most aggressive procedures , to the extent that the functional outcome may rely on it .