et. at. (2000) conducted an extremely thorough investigation of chronic electrical stimulation. of tDe thyroarytenoid muscle in a dog model. An animal model was requireo prior to use on humans. The size and proportion of the laryngeal structures or canlnes Is tDe closest to those of humans and it was for this reason that dogs were used in. the study. Ludlow et at. (2000) specifically sought to provide information pertaining to etrects of chronic muscle stimulation and the extent of tissue damage. Luolow et at. tfuuu) round tfat In their sample of six canines that had been chroni- cally intermittently stimulated with implanted electrodes for 8 hours a day,5 days a week for up to 8 months, there were small differences between stimulated and non- stimulated muscles. However, the authors note that the sample sizes were small and that the 16 hours that the stimulation was withheld daily would have contributed to muscle recovery, Failure of relaxation of the muscle results in persistent shorteninr or tao muscle causing contractures. This Is clearly not something that would assist swallowing recovery. Considerably more research into the long-term effect of elec- trical stimulation is required with larger sample sizes.
Electrical stimulation for swallowing rehabilitation using surface electrodes Electrlcal stimulation to improve swallowing function has also been employed usinr surt'ace electrodes. Leelamanit et at. (2002) .reported surface electrode placement over the submandibular gland in order to stimulate the thyrohyoid muscle in order to Improve laryngeal elevation, The justifieation for choice of site of placement and tar- get muscle group was not well demonstrated. Patients in this study were stimulated for four hours a day until they fulfilled the criteria for improved swallowing or until it was demonstrated that other interventions were required. There was no justifica- tion provided for the length of time that stimulation occurred. There was also no justification of the pulse type, pulse (requency or size of the stimulating electrodes despite the fact that the authors recogniBed and reported that these parameters were critical to'successful neuromuscular electrical stimulation rehabilitationi.
electrical stimulation protocol with a thermal-tactile stimulation protocol. There was no control group. The authors included both inclusion and exclusion criteria. There were different numbers of patients assigned to the electrical stimulation and thermal stimulation groups, making it difHcult to compare the two techniques for effcacy. The patient characteristics in the two groups was also quite different. For the electri- cal stimulation group two different electrode placement patterns were used. One had placement of the electrodes on either the right or left side with'the upper electrode placed above the lesser horns of the hyoid bone on the digastric muscle and the lower electrode placed on the thyrohyoid muscle at the level of the top of ;the crico- thyroid cartilage'(Freed et al.,2001, p.469). This position was used for the majority of Patients. For Patients with tracheostomies or whose anatomy prevented use of the previous configuration, the following placement parameters were used: ion either side of the midline, above the lesser horns of the hyoid bone on the digastric muscle'
S WA LL OWINe R I HA B ILITAT iON 379
(freed et at.,2001, p.469). These are obviously quite different placement and com- parability of results gained from the two placements is questionable. For both place- ments a physical therapist and a speech pathologist applied the electrodes. The au- thors note that the electrodes were repositioned until muscle fasciculations occurred or the'strongest contraction was observed during the swallowing response'. There appears to be little scientific basis fer this criteria for electrode placement. Note also that current intensity was'set at the patient's tolerance and comfort level'. However, it is also noted that some individuals who participated in the study had aphasia. The authors do not demonstrate how they determined whether aphasia affected the individual's ability to indicate comfort level reliably. Intensity of the electrical signal was increased in increments of 2.5mA up to a maximum of 25mA to the individual's comfort and tolerance level. Of concern the authors state that 'when ES was successful in obtaining a voluntary swallow response, the patient was asked to attempt to swallow...'a specific fluid consistency (p.469). The concern is that the intensity of the stimulation appears to have been ramped up until a response was gained with little checks in place to ensure that skin damage or indeed muscle damage did not also occur, The stimulation was reported to have been delivered for 60 minutes, in a continuous mode with a one second pause between each minute. There is insufscient detail to be sure (a) how often the individual was required to swallow during the electrical stimulation (i.e. participate in a functional task) or (b) if the·stimulation occurred continuously, regardless of whether the poison was swal- lowing or not. Research from the exercise physiology literature would question the utility of the latter. This study did not vary the amount of stimulation of ffred (dose) per patient nor did it gradually increase the duration of the stimulation on a daily basis. In this context it is very difacult to agree with the author's interpretations of the results. Further well-designed research is required in this feld. -
Contraindications for use of electrical stimulation
The literature supports the statements that electrical stimulation is contraindicated in patients with (a) carotid sensitivity, (b) evidence of heart block, (c) patients using pacemakers, (d) patients who are pregnant, (e) those with hypersensitive skin, and (f) those recovering from surgery at or very close to the site of intended electrode placement (Huckabee and Pelletier, 1999; Leelamanit et al., 2002). The head and neck are densely vascularized and innervated, consequently skill and expertise is required for accurate placement of the electrodes in addition to consideration of populations to avoid (e.g. cancer, radiotherapy, chemotherapy). Electrical stimulation can also cause (i) chemical burns if applied to Injured skin or for a prolonged duration, (ii) heat burn due to the intensify of the current, (iii) potential for electrical shock, (iv) spreading of infection due to the muscle excitation effect, and (v) muscle soreness with prolonged and intensive use (LeeBamanit et al., 2002). The use of electrical stimulation in patients following radiotherapy should also be cautioned if the intended site of placement of the electrodes is within the radiotherapy Held.
DYSPHAGIA: fOUNDATiON, THEORY AND PRACTICE Many of the electrical stimulation studies provide insufDcient data to determine the voltage and amperage used in their studies. Moreover where some of these values are recorded, there is little consistency in them! Both of the studies using surface electrical stimulation techniques are poorly designed, with thin hypotheses, insuf- ficient information about inclusion and exclusion criteria, no use of randomiBation or control groups and results confounded by natural recovery. There is insuffcient information to state whether surface stimulation has a primary effect on the muscle beneath it, peripheral nerves attached to the muscle or near to the muscle or some combination of both. In addition, both studies applied the stimulation in block fash- ion for either one hour or four hours, without pairing the stimulation with functional swallowing tasks (Freed et at.,2001; Leelamanit et at.,2002), Both studies serve nothing more than to show there may be potential for the use of electrical stimula- tion in the rehabilitation of swallowing, but there are a significant number of ques- tions to be answered before it is routinely applied In the clinical setting. Issues of training accreditation also need to be addressed.
BiOFEEDBACK IN THE REHABILITAT10N OF SWALLOWING
Biofredback is an external means of providing ffedback to a patient and is intended to increase the rate of motor learning, thus improving the efsciency of treatment (Crary et al.,2004). That ffedback may be provided in the form of (a) specific comments from the therapist, (b) a visuaB image while performing a task (e.g. endoscopy, vid- eofluoroscopy, visual display attached to electromyography device), or (c) auditory feedback (e.g. cervical auscultation). Biofeedback has been shown to enhance new loam'ins. It is a method of providing additional input to internal·sensorimotor feedback and allows an individual to shape their behaviour based on what they see', hear or ffeB. Bioffedback is encouraged as a useful adjunct for rehabilitation of function and is designed to be used in combination with the therapeutic exercises and compensatory strategies described elsewhere in this text. It is a temporary adjunct that gives the pa- tiellt information about'the right way'fD17 them to swallow or prepare the bolus safely. Surface electromyography is often cited as a useful biofeedback device for swallowing rehabilitation. The evidence base for its use is small, however, the principles underly- ing why it should be useful are sound. Videofluoroscopy and endoscopy of swallowing and cervical auscultation can also be used in varying degrees to provide bioffedback.
SURfACE SLRCTROMYOGRAPHY - sEMG
Surface electromyography (SEMG) is a means of measuring the myoel?ctric im- pulses generated by the muscle just before it contracts (Abernethy et al.,2005). The signal generated is fed into a device that produces a visual signal of a raw wavefDrm that is then'smoothed to provide a more'user-friendly'visual display for the patient. Typically the amplitude or strength of the movement is depicted along the vertical axis and the timing of the contraction is displayed along the horizontal axis. In the surface format EMG is applied using electrodes onto the skin surface. However
EHG can also be applied invasively, using hooked wire electrodes into the body of the muscle (Sonies 1991, Sonies and Baum, 1988). Intramuscular placement is required to use EMC in a diagnostic format. It requires considerable skill, training and knowledge of head and neck anatomy. Given its invasive nature, intramuscular EMG is not widely used In clinical practice. SEMG on the other hand is non-invasive and provides the clinician with an accurate indication of the functional activity of the muscles it overlies (Huckabee and Pelletier, 1999). With the electrodes placed on the surface and due to the hlgh degree of overlapping muscles in the face and neck, it is very difficult to isolate a single muscle. In fact it is more often a group of muscles that are being recorded. For this reason, SEMG should not be used for diagnostic purposes, but should be reserved for rehabilitation via biofeedback. In addition, due to vast intra-individual variability, patients should serve as their own controls. SEMC has been advocated to (a) promote a reduction in tone where spastic- ity appears likely, (b) improve coordination and motor patterning, and (c) assist do- velopment of muscle recruitment where the muscle/s appear to be weak or paralysed (ITuckabee and Pelletier, 1999). The reader is referred to Huckabee and Pelletier (1999) for a detailed account of the use of SEMG for rehabilitation of swallowing. Some brief points are presented below. Huckabee and Pelletier (1999) explain that the biofeedback afforded by SEMG facilitates a patient's awareness of muscular contractions associated with swallow- ing. In clinical practice electrodes are most often placed on the submental muscles to facilitate feedback on swallow initiation afd the suprahroids to faciliiate feedback on laryngeal excursion (Huckabee and Cannito, 1999). Electrode placement is criti- cal. Electl'odes need to be placed on the belly of the muscle rather than the points of insertion. While this is obviously easier with large muscles in the limbs, the task be- comes muc more diffcult with the small and overlapping muscles of the face,'floor of mouth and throat. The distance that the electrodes are placed apart is also impor- tant, because the electrodes will measure as deep as the active and referent electrodes are spaced apart. Thus the closer together the electrodes are placed the smaller the amount of information gleaned, while further distance apart may enhance the signal (Huckabee and Pelletier,1999). Finally it also matters whether the electrode is large or small. Smaller electrodes tend to provide a more specifc measurement than larger ones. With larger electrodes a greater surface area Is recorded and the specificity of the measurement is therefore reduced (Huckabee and Pelletier,1999). Huckabee and Cannito (1999) reported some of the characteristics of the oscilloscope display one might expect when different swallowing manoeuvres are employed. For example, they state that during employment of the Masako exercise, the visual display shows a high peak amplitude for a short duration, deemed representative of rapid contrac- tion, and relaxation of the suprahyoids during swallowing. In contrast, during the Mendelsohnmanoeuvre atypical oscilloscope display may show arapid onsetrise in amplitude followed by a sustained high amplitude trace (while the larynx is elevated against gravity) for a few seconds before an abrupt drop in amplitude signalling the end of the manoeuvre (larynx returns to rest) and return to rest. SEMG has been reported in two recent clinical studies airhed at rehabilitation of swallowing in individuals with chronic dysphagia (symptoms >6 months)
DYSPHAGIA: fOUNDATiON, THEORY AND PRACTll
(Huckabee and Cannito, 1999; Crary et at., 2004). Huckabee and Cannito (19? used a small sample of individuals with chronic dysphagia secondary to brain stf injury. Information regarding placement of the electrodes was inconclusive, stati only that submental and suprahyoid muscles were targeted. Treatment was intr sive, utilizing one hour of direct therapy each morning and mid-afternoon wilt rest period of 3-4 hours between sessions. Treatment continued for five consecuti days. In addition, patients were given a home programme to be carried out thl times during the week which relied on independent sessions using the SEMG 15 minutes'duration. It could be argued that the benefit of the home programl may well have been negligible given the short and inconsistent duration of the he] treatment. Treatment was patient specific and utilized SEMG in conjunction w swallowing manoeuvres such as the Mendelsohn manoeuvre, Masako exercise, t head-lift manoeuvre and effortful swallow as required. Direct oral intake was a] incorporated as early as was safely possible into the treatment programme. This ty of programme is quite well designed; it makes use of biofeedback, physiologies sound manoeuvres and a contextual setting (trials of food). The results of the sm study showed that there were improvements in swallowing physiology, pulmonT status and type of foods and fluids the patient was able to safely eat. Interestingly f patients that improved reported that they were no longer using compensatory to( niques to swallow safely. This does not appear to have been formally investigatr and much like the Prosiegel et al. (2000) study, the patients may in fact have be using the terhniques without conscious awareness. That is, they may have achiey stage 3- the automatism phase of learning. Crary et al, (2004) investigated a mixed population of stroke and head/neck sl gical individuals with dysphagia symptoms in evidence for more than six months. this study,'individuals participated in daily 50-minute clinical sessions. In additi( the patients were asked to· complete two home therapy sessions per day; howev there was no indication of the suggested time frame for these home therapy sl sions. Number of therapy sessions ranged from four to 28. Therapy was discontinu when both the patient and the clinician agreed that further improvement was 1 likely. Electrodes were placed on the anterior neck between the hyoid bones a the superior border of the thyroid cartilage. The ground electrode was placed of the thyroid notch area, with each active electrode placed to the right and left of I ground electrode. A very functional approach was employed where SEMG was us to facilitate techniques to Improve bolus control and airway protection. True to f pl'inclples of exercise physiology, an ascending threshold approach was employ whereby the patient had to progressively increase swallow effort to obtain an aui tory signal indicating success. Bolus volume and viscosity were also systematica manipulated. The results of the study indicated that the structural behavi?ural p] gramme was most beneficial for the stroke population. Crary et al. (2004) sugg- that the swallowing pattern is more amenable to rehabilitation when the dysphai is physiologically based rather than mechanically based, as in the case of head/ue surgery. The authors suggested that'head/neck patients may be less likely to hf the physiologic capability to change swallowing patterns'(p.164), however,1 vol
argue that with cognition preserved, these Individuals are better candidates for swal- lowing re-education. The challenge for the therapist is in assisting the patient to find new patterns, or strategies to help them achieve functional swallowing.
PHARYNGEAL EMG
EMG activity of the pharyngeal phase of swallowing is rarely undertaken due to the difficulties in placement of the electrodes. Previous investigators have reported recording EMG activity from the superior pharyngeal constrictors using hooked wire electrode placement dlrectly into the muscle (Perlman et at., 1989), A more novel and less invasive approach has been described by Palmer et at. (1989) where bipolar suction electrodes were adhered to the mucosa of the posterior pharyngeal wall and provided information from the stable underlying constrictor muscles. The researchers indicated that choice of electrode type (hooked wire electrode, needle electrode or bipolar suction electrode) was dependent on the purpose of the study and the muscles selected for study. Indeed some of the electrode types were better for certain muscles than others. The ability to reliably record from cricopharyngeus remains technically challenging, however. Further research is requiied to develop normative data for recruitment patterns using these EMG devices. Cer'tainly reliable and ?inimally invaslve pharyngeal EMG may be very helpful in providing feedback to individuals with pharyngeal stage dysphagia.
Other biofeedback mechanisms for swallowing rehabilitation As noted above, videoHuoroscopy and endoscopy of swallowing may provide useful biofcedback. It is more difscult to use videoauoroscopy in a biofeedb·act modality due to the ethical issues of keeping radiation exposure to a minimum. However, if the patient is taught a rehabilitative manoeuvre or exercise (e.g. Mendelsohn ma- noeuvre etc.) the clinician can use the images to show the individual the result of applying the manoeuvre, perhaps allowing the individual to better visualize what it is they are trying to achieve, Endoscopy of swallowing affords more real-time use of biofeedback. For example, the monitor can be positioned so that the patient can clearly see copious secretions in the pharynx, be instructed to swallow and then see and feel the result of a successful swallow in clearing the secretions. Techniques such as the supraglottic swallow can be taught in segments using endoscopy. For example, the patient can be taught the breath hold and release component of the task and can watch as the cords close. They can also see and experience the difference between the supraglottic swallow and the more forceful super-supraglottic swallow. Even for individuals without the cognitive skills to perform these manoeuvres, the ability to see food or fluid residue in the pharynx prior to or after the swallow and then see the result of a clearing swallow in removing the residue may allow them to better learn a prophylactic clearing swallow. Cervical auscultation can also be used for biofredback. Attachment of a small throat microphone to a portable amplifer will allow both clinician and patient to
DYSPHAGIA: FOUNDATrON, THEORY AND PRACTICE
determine the synchrony of swallowing and respiration. It allows them to hear a pri- mary swallow and any clearing swallows; with clearing swallows encouraged if this Is required. It also allows them to hear for changes in respiration quality (wet) and speed (fast) post swallow. Changes to swallowing sounds and post swallow respira- tory sounds can also be monitored during the employment of swallowing manoeu- vres or exercises to determine whether they assist, hinder or make no difference to the swallow-respiratory cycle.
A POPULAT10N OF SPECIAL NOTE - TREATMENT OF THE PATIENT WHO IS NIL BY MOUTH (NBM)
Individuals with severe dysphagia, reduced or fluctuating levels of alertness or frail medical condition are often placed nil by mouth (NBM). Often times these individu- als have an IV line placed and a nasogastric tube (NGT) to meet their nutritional needs, with the NGT aimed at being a temporary measure. For the dysphagia clini- cian, it is imperative that individuals who are placed nil orally are placed as high priority for dysphagia rehabilitation and prophylactic measures to reduce the likeli- hood of the development of aspiration pneumonia. Akner and Decerholm (2001) reported that greater than 80 per cent of patients hospitalized for m?re than 21 days had difsculty eating and that half of all patients referred to stroke rehabilitation were malnourished. Tube feeding is considered a predictor for the development of aspiration pneu- monia (Langmore et at, 1998). The reasons for this are as follows. Salivary flow rate is reduced in the NBM patient due to the fact that food and Huids no longer stimulate saliva production. This ?e'duction in saliva aow allows the coloniaation of pathogenic organisms in the oral cavity. If these pathogenic orglnisLs are aspi- rated, a chest infection is the likely outcome unless the patient's immune response can deal with the organisms. However, if the immune funetion is compromised by malnutrition, then the risk of infection is higher (Perry and McLaren,2003), In ad- dition to this, note the previous discussions relating to disuse atrophy of muscles. Without a reason to swallow (i.e. food and fluid intake), the individual has fewer op- portunities to use these muscles in a functional context. The elderly population may already be do-conditioned and thus at higher risk for malnutrition prior to hospitali- zation. Further, dehydration and malnutrition cause reduced muscle strength, high levels of fatigue, and reduced immunological function (Olde Rikkert and Rigaud, 2003) and therefore, a cycle of systematic decline. Consequently if the patient is suf- (iciently alert, the clinician sheuld aim at providing activities to induce at least saliva swallows (e.g. tastes of lemon ice or silcklng on a lollipop - see previous discussion). The'move it or lose it'concept needs to be uppermost for the dysphagia clinician. Note also the importance of good oral hygiene to reduce the likelihood of coloni- zation of pathogenic oral bacteria. In a recent cost analysis study it was reported that a single hospitalization for aspiration pneumonia presents an average cost of US$6,000 (Waters et at,,2004), The dysphagia clinician should make every effort to advocate for early nutrition and hydration, good oral hygiene, and short bursts of
rehabilitation treatment as soon as the patient is able to tolerate it. These strategies may help reduce the likelihood of the development of aspiration pneumonia specifi- cally due to nil oral status, which benefits the individual by improving quality of life and potentially decreases morbidity and mortality (Waters et at.,2004). Thus rather than waiting for the patient to improve, the clinician should actively treat the NBM patient as early as possible to maximiEe recovery.
SUMMARY
This chapter discusses the importance of evidence-based practice for dysphagia re- habilitation. It shows that the'evidence'for dysphagia rehabilitation is based on a small number of studies that often have small sample sizes. Where evidence does not exist, the clinician should ask whether the proposed treatment technique has solid foundations that support a view that it'should'work. This chapter provided a treatment style that is based on the principles underpinning exercise physiology and motor learning in a functional context. Tt also highlighted the psychological issues surrounding rehabilitation such as patient Insight, motivation and a?tive participa- tion in goal-setting. Using a different approach to most texts, this chapter aimed to provide clinicians with a starting point for functional rehabilitation ?f swallowing function. It also described the role of feedback and biofeedback in .?ehabilitatio?. Finally it concluded with discussions regarding the NBM patient. It is particularly important that NBM patients receive every opportunity to participate in a rehabilita- tion programme or modified rehabilitation programme to ensure that muscles used in swallowing are not further depleted by disuse atrophy. Clinicians should read this chapter together with Chapter 11 regarding compensation, as the majority of patients, and particularly those with dysphagia of neurological origin will require judicious use of both principles in achieving oral intake. Oral intake should be the cliniciln's goal to maximize an individual's ability to participate in social activities that are imperative for healthy physical, social, mental and psychological well-being. Research into the field of rehabilitation of dysphagia is in its infancy and individu- als and researchers are strongly encouraged to add to the evidence for its efficacy. It will be prudent to liaise with experts in human movement studies to obtain the best outcomes for our patients.
REFERENCES
Abernethy 3, Hanrahan SJ, Kippers V, Mckinnon LT, Pandy MG (2005) The Biophysical Foundations of Human Movement (2nd edn). Lower Mitchum SA: Human Kinetics'. Akner C, Decerholm T (2001) Treatment of protein-energy malnutrition in chronic non- malignant disorders. American Journal of Clinical Nutrition 74: 6-24. Aronson AE (1985) Clinical Voice Disorders: An Interdisciplinary Approach (2nd eOn). New York: Thieme. Barbui C (2005) Evidence-based medicine and medicine-based evidence. Neurological Sci- ence 26 : 145-6.
ㅡㅡ
BYSPHAGIA: FOUNDATiON, THEORY AND PRACTICe
et. at. (2000) conducted an extremely thorough investigation of chronic electrical
stimulation. of tDe thyroarytenoid muscle in a dog model. An animal model was
requireo prior to use on humans. The size and proportion of the laryngeal structures
or canlnes Is tDe closest to those of humans and it was for this reason that dogs were
used in. the study. Ludlow et at. (2000) specifically sought to provide information
pertaining to etrects of chronic muscle stimulation and the extent of tissue damage.
Luolow et at. tfuuu) round tfat In their sample of six canines that had been chroni-
cally intermittently stimulated with implanted electrodes for 8 hours a day,5 days a
week for up to 8 months, there were small differences between stimulated and non-
stimulated muscles. However, the authors note that the sample sizes were small and
that the 16 hours that the stimulation was withheld daily would have contributed to
muscle recovery, Failure of relaxation of the muscle results in persistent shorteninr
or tao muscle causing contractures. This Is clearly not something that would assist
swallowing recovery. Considerably more research into the long-term effect of elec-
trical stimulation is required with larger sample sizes.
Electrical stimulation for swallowing rehabilitation using surface electrodes
Electrlcal stimulation to improve swallowing function has also been employed usinr
surt'ace electrodes. Leelamanit et at. (2002) .reported surface electrode placement
over the submandibular gland in order to stimulate the thyrohyoid muscle in order to
Improve laryngeal elevation, The justifieation for choice of site of placement and tar-
get muscle group was not well demonstrated. Patients in this study were stimulated
for four hours a day until they fulfilled the criteria for improved swallowing or until
it was demonstrated that other interventions were required. There was no justifica-
tion provided for the length of time that stimulation occurred. There was also no
justification of the pulse type, pulse (requency or size of the stimulating electrodes
despite the fact that the authors recogniBed and reported that these parameters were
critical to'successful neuromuscular electrical stimulation rehabilitationi.
electrical stimulation protocol with a thermal-tactile stimulation protocol. There was
no control group. The authors included both inclusion and exclusion criteria. There
were different numbers of patients assigned to the electrical stimulation and thermal
stimulation groups, making it difHcult to compare the two techniques for effcacy.
The patient characteristics in the two groups was also quite different. For the electri-
cal stimulation group two different electrode placement patterns were used. One had
placement of the electrodes on either the right or left side with'the upper electrode
placed above the lesser horns of the hyoid bone on the digastric muscle and the
lower electrode placed on the thyrohyoid muscle at the level of the top of ;the crico-
thyroid cartilage'(Freed et al.,2001, p.469). This position was used for the majority
of Patients. For Patients with tracheostomies or whose anatomy prevented use of the
previous configuration, the following placement parameters were used: ion either
side of the midline, above the lesser horns of the hyoid bone on the digastric muscle'
S WA LL OWINe R I HA B ILITAT iON 379
(freed et at.,2001, p.469). These are obviously quite different placement and com-
parability of results gained from the two placements is questionable. For both place-
ments a physical therapist and a speech pathologist applied the electrodes. The au-
thors note that the electrodes were repositioned until muscle fasciculations occurred
or the'strongest contraction was observed during the swallowing response'. There
appears to be little scientific basis fer this criteria for electrode placement.
Note also that current intensity was'set at the patient's tolerance and comfort
level'. However, it is also noted that some individuals who participated in the study
had aphasia. The authors do not demonstrate how they determined whether aphasia
affected the individual's ability to indicate comfort level reliably. Intensity of the
electrical signal was increased in increments of 2.5mA up to a maximum of 25mA
to the individual's comfort and tolerance level. Of concern the authors state that
'when ES was successful in obtaining a voluntary swallow response, the patient was
asked to attempt to swallow...'a specific fluid consistency (p.469). The concern is
that the intensity of the stimulation appears to have been ramped up until a response
was gained with little checks in place to ensure that skin damage or indeed muscle
damage did not also occur, The stimulation was reported to have been delivered for
60 minutes, in a continuous mode with a one second pause between each minute.
There is insufscient detail to be sure (a) how often the individual was required to
swallow during the electrical stimulation (i.e. participate in a functional task) or (b)
if the·stimulation occurred continuously, regardless of whether the poison was swal-
lowing or not. Research from the exercise physiology literature would question the
utility of the latter. This study did not vary the amount of stimulation of ffred (dose)
per patient nor did it gradually increase the duration of the stimulation on a daily
basis. In this context it is very difacult to agree with the author's interpretations of
the results. Further well-designed research is required in this feld. -
Contraindications for use of electrical stimulation
The literature supports the statements that electrical stimulation is contraindicated
in patients with (a) carotid sensitivity, (b) evidence of heart block, (c) patients using
pacemakers, (d) patients who are pregnant, (e) those with hypersensitive skin, and
(f) those recovering from surgery at or very close to the site of intended electrode
placement (Huckabee and Pelletier, 1999; Leelamanit et al., 2002). The head and
neck are densely vascularized and innervated, consequently skill and expertise is
required for accurate placement of the electrodes in addition to consideration of
populations to avoid (e.g. cancer, radiotherapy, chemotherapy).
Electrical stimulation can also cause (i) chemical burns if applied to Injured skin
or for a prolonged duration, (ii) heat burn due to the intensify of the current, (iii)
potential for electrical shock, (iv) spreading of infection due to the muscle excitation
effect, and (v) muscle soreness with prolonged and intensive use (LeeBamanit et al.,
2002). The use of electrical stimulation in patients following radiotherapy should
also be cautioned if the intended site of placement of the electrodes is within the
radiotherapy Held.
DYSPHAGIA: fOUNDATiON, THEORY AND PRACTICE
Many of the electrical stimulation studies provide insufDcient data to determine
the voltage and amperage used in their studies. Moreover where some of these values
are recorded, there is little consistency in them! Both of the studies using surface
electrical stimulation techniques are poorly designed, with thin hypotheses, insuf-
ficient information about inclusion and exclusion criteria, no use of randomiBation
or control groups and results confounded by natural recovery. There is insuffcient
information to state whether surface stimulation has a primary effect on the muscle
beneath it, peripheral nerves attached to the muscle or near to the muscle or some
combination of both. In addition, both studies applied the stimulation in block fash-
ion for either one hour or four hours, without pairing the stimulation with functional
swallowing tasks (Freed et at.,2001; Leelamanit et at.,2002), Both studies serve
nothing more than to show there may be potential for the use of electrical stimula-
tion in the rehabilitation of swallowing, but there are a significant number of ques-
tions to be answered before it is routinely applied In the clinical setting. Issues of
training accreditation also need to be addressed.
BiOFEEDBACK IN THE REHABILITAT10N OF SWALLOWING
Biofredback is an external means of providing ffedback to a patient and is intended to
increase the rate of motor learning, thus improving the efsciency of treatment (Crary
et al.,2004). That ffedback may be provided in the form of (a) specific comments
from the therapist, (b) a visuaB image while performing a task (e.g. endoscopy, vid-
eofluoroscopy, visual display attached to electromyography device), or (c) auditory
feedback (e.g. cervical auscultation). Biofeedback has been shown to enhance new
loam'ins. It is a method of providing additional input to internal·sensorimotor feedback
and allows an individual to shape their behaviour based on what they see', hear or ffeB.
Bioffedback is encouraged as a useful adjunct for rehabilitation of function and is
designed to be used in combination with the therapeutic exercises and compensatory
strategies described elsewhere in this text. It is a temporary adjunct that gives the pa-
tiellt information about'the right way'fD17 them to swallow or prepare the bolus safely.
Surface electromyography is often cited as a useful biofeedback device for swallowing
rehabilitation. The evidence base for its use is small, however, the principles underly-
ing why it should be useful are sound. Videofluoroscopy and endoscopy of swallowing
and cervical auscultation can also be used in varying degrees to provide bioffedback.
SURfACE SLRCTROMYOGRAPHY - sEMG
Surface electromyography (SEMG) is a means of measuring the myoel?ctric im-
pulses generated by the muscle just before it contracts (Abernethy et al.,2005). The
signal generated is fed into a device that produces a visual signal of a raw wavefDrm
that is then'smoothed to provide a more'user-friendly'visual display for the patient.
Typically the amplitude or strength of the movement is depicted along the vertical
axis and the timing of the contraction is displayed along the horizontal axis. In
the surface format EMG is applied using electrodes onto the skin surface. However
EHG can also be applied invasively, using hooked wire electrodes into the body
of the muscle (Sonies 1991, Sonies and Baum, 1988). Intramuscular placement is
required to use EMC in a diagnostic format. It requires considerable skill, training
and knowledge of head and neck anatomy. Given its invasive nature, intramuscular
EMG is not widely used In clinical practice. SEMG on the other hand is non-invasive
and provides the clinician with an accurate indication of the functional activity of
the muscles it overlies (Huckabee and Pelletier, 1999). With the electrodes placed
on the surface and due to the hlgh degree of overlapping muscles in the face and
neck, it is very difficult to isolate a single muscle. In fact it is more often a group
of muscles that are being recorded. For this reason, SEMG should not be used for
diagnostic purposes, but should be reserved for rehabilitation via biofeedback. In
addition, due to vast intra-individual variability, patients should serve as their own
controls. SEMC has been advocated to (a) promote a reduction in tone where spastic-
ity appears likely, (b) improve coordination and motor patterning, and (c) assist do-
velopment of muscle recruitment where the muscle/s appear to be weak or paralysed
(ITuckabee and Pelletier, 1999). The reader is referred to Huckabee and Pelletier
(1999) for a detailed account of the use of SEMG for rehabilitation of swallowing.
Some brief points are presented below.
Huckabee and Pelletier (1999) explain that the biofeedback afforded by SEMG
facilitates a patient's awareness of muscular contractions associated with swallow-
ing. In clinical practice electrodes are most often placed on the submental muscles
to facilitate feedback on swallow initiation afd the suprahroids to faciliiate feedback
on laryngeal excursion (Huckabee and Cannito, 1999). Electrode placement is criti-
cal. Electl'odes need to be placed on the belly of the muscle rather than the points of
insertion. While this is obviously easier with large muscles in the limbs, the task be-
comes muc more diffcult with the small and overlapping muscles of the face,'floor
of mouth and throat. The distance that the electrodes are placed apart is also impor-
tant, because the electrodes will measure as deep as the active and referent electrodes
are spaced apart. Thus the closer together the electrodes are placed the smaller the
amount of information gleaned, while further distance apart may enhance the signal
(Huckabee and Pelletier,1999). Finally it also matters whether the electrode is large
or small. Smaller electrodes tend to provide a more specifc measurement than larger
ones. With larger electrodes a greater surface area Is recorded and the specificity of
the measurement is therefore reduced (Huckabee and Pelletier,1999). Huckabee and
Cannito (1999) reported some of the characteristics of the oscilloscope display one
might expect when different swallowing manoeuvres are employed. For example,
they state that during employment of the Masako exercise, the visual display shows
a high peak amplitude for a short duration, deemed representative of rapid contrac-
tion, and relaxation of the suprahyoids during swallowing. In contrast, during the
Mendelsohnmanoeuvre atypical oscilloscope display may show arapid onsetrise in
amplitude followed by a sustained high amplitude trace (while the larynx is elevated
against gravity) for a few seconds before an abrupt drop in amplitude signalling the
end of the manoeuvre (larynx returns to rest) and return to rest.
SEMG has been reported in two recent clinical studies airhed at rehabilitation
of swallowing in individuals with chronic dysphagia (symptoms >6 months)
DYSPHAGIA: fOUNDATiON, THEORY AND PRACTll
(Huckabee and Cannito, 1999; Crary et at., 2004). Huckabee and Cannito (19?
used a small sample of individuals with chronic dysphagia secondary to brain stf
injury. Information regarding placement of the electrodes was inconclusive, stati
only that submental and suprahyoid muscles were targeted. Treatment was intr
sive, utilizing one hour of direct therapy each morning and mid-afternoon wilt
rest period of 3-4 hours between sessions. Treatment continued for five consecuti
days. In addition, patients were given a home programme to be carried out thl
times during the week which relied on independent sessions using the SEMG
15 minutes'duration. It could be argued that the benefit of the home programl
may well have been negligible given the short and inconsistent duration of the he]
treatment. Treatment was patient specific and utilized SEMG in conjunction w
swallowing manoeuvres such as the Mendelsohn manoeuvre, Masako exercise, t
head-lift manoeuvre and effortful swallow as required. Direct oral intake was a]
incorporated as early as was safely possible into the treatment programme. This ty
of programme is quite well designed; it makes use of biofeedback, physiologies
sound manoeuvres and a contextual setting (trials of food). The results of the sm
study showed that there were improvements in swallowing physiology, pulmonT
status and type of foods and fluids the patient was able to safely eat. Interestingly f
patients that improved reported that they were no longer using compensatory to(
niques to swallow safely. This does not appear to have been formally investigatr
and much like the Prosiegel et al. (2000) study, the patients may in fact have be
using the terhniques without conscious awareness. That is, they may have achiey
stage 3- the automatism phase of learning.
Crary et al, (2004) investigated a mixed population of stroke and head/neck sl
gical individuals with dysphagia symptoms in evidence for more than six months.
this study,'individuals participated in daily 50-minute clinical sessions. In additi(
the patients were asked to· complete two home therapy sessions per day; howev
there was no indication of the suggested time frame for these home therapy sl
sions. Number of therapy sessions ranged from four to 28. Therapy was discontinu
when both the patient and the clinician agreed that further improvement was 1
likely. Electrodes were placed on the anterior neck between the hyoid bones a
the superior border of the thyroid cartilage. The ground electrode was placed of
the thyroid notch area, with each active electrode placed to the right and left of I
ground electrode. A very functional approach was employed where SEMG was us
to facilitate techniques to Improve bolus control and airway protection. True to f
pl'inclples of exercise physiology, an ascending threshold approach was employ
whereby the patient had to progressively increase swallow effort to obtain an aui
tory signal indicating success. Bolus volume and viscosity were also systematica
manipulated. The results of the study indicated that the structural behavi?ural p]
gramme was most beneficial for the stroke population. Crary et al. (2004) sugg-
that the swallowing pattern is more amenable to rehabilitation when the dysphai
is physiologically based rather than mechanically based, as in the case of head/ue
surgery. The authors suggested that'head/neck patients may be less likely to hf
the physiologic capability to change swallowing patterns'(p.164), however,1 vol
argue that with cognition preserved, these Individuals are better candidates for swal-
lowing re-education. The challenge for the therapist is in assisting the patient to find
new patterns, or strategies to help them achieve functional swallowing.
PHARYNGEAL EMG
EMG activity of the pharyngeal phase of swallowing is rarely undertaken due to
the difficulties in placement of the electrodes. Previous investigators have reported
recording EMG activity from the superior pharyngeal constrictors using hooked
wire electrode placement dlrectly into the muscle (Perlman et at., 1989), A more
novel and less invasive approach has been described by Palmer et at. (1989) where
bipolar suction electrodes were adhered to the mucosa of the posterior pharyngeal
wall and provided information from the stable underlying constrictor muscles. The
researchers indicated that choice of electrode type (hooked wire electrode, needle
electrode or bipolar suction electrode) was dependent on the purpose of the study
and the muscles selected for study. Indeed some of the electrode types were better
for certain muscles than others. The ability to reliably record from cricopharyngeus
remains technically challenging, however. Further research is requiied to develop
normative data for recruitment patterns using these EMG devices. Cer'tainly reliable
and ?inimally invaslve pharyngeal EMG may be very helpful in providing feedback
to individuals with pharyngeal stage dysphagia.
Other biofeedback mechanisms for swallowing rehabilitation
As noted above, videoHuoroscopy and endoscopy of swallowing may provide useful
biofcedback. It is more difscult to use videoauoroscopy in a biofeedb·act modality
due to the ethical issues of keeping radiation exposure to a minimum. However, if
the patient is taught a rehabilitative manoeuvre or exercise (e.g. Mendelsohn ma-
noeuvre etc.) the clinician can use the images to show the individual the result of
applying the manoeuvre, perhaps allowing the individual to better visualize what it
is they are trying to achieve, Endoscopy of swallowing affords more real-time use
of biofeedback. For example, the monitor can be positioned so that the patient can
clearly see copious secretions in the pharynx, be instructed to swallow and then see
and feel the result of a successful swallow in clearing the secretions. Techniques
such as the supraglottic swallow can be taught in segments using endoscopy. For
example, the patient can be taught the breath hold and release component of the task
and can watch as the cords close. They can also see and experience the difference
between the supraglottic swallow and the more forceful super-supraglottic swallow.
Even for individuals without the cognitive skills to perform these manoeuvres, the
ability to see food or fluid residue in the pharynx prior to or after the swallow and
then see the result of a clearing swallow in removing the residue may allow them to
better learn a prophylactic clearing swallow.
Cervical auscultation can also be used for biofredback. Attachment of a small
throat microphone to a portable amplifer will allow both clinician and patient to
DYSPHAGIA: FOUNDATrON, THEORY AND PRACTICE
determine the synchrony of swallowing and respiration. It allows them to hear a pri-
mary swallow and any clearing swallows; with clearing swallows encouraged if this
Is required. It also allows them to hear for changes in respiration quality (wet) and
speed (fast) post swallow. Changes to swallowing sounds and post swallow respira-
tory sounds can also be monitored during the employment of swallowing manoeu-
vres or exercises to determine whether they assist, hinder or make no difference to
the swallow-respiratory cycle.
A POPULAT10N OF SPECIAL NOTE - TREATMENT OF THE
PATIENT WHO IS NIL BY MOUTH (NBM)
Individuals with severe dysphagia, reduced or fluctuating levels of alertness or frail
medical condition are often placed nil by mouth (NBM). Often times these individu-
als have an IV line placed and a nasogastric tube (NGT) to meet their nutritional
needs, with the NGT aimed at being a temporary measure. For the dysphagia clini-
cian, it is imperative that individuals who are placed nil orally are placed as high
priority for dysphagia rehabilitation and prophylactic measures to reduce the likeli-
hood of the development of aspiration pneumonia. Akner and Decerholm (2001)
reported that greater than 80 per cent of patients hospitalized for m?re than 21 days
had difsculty eating and that half of all patients referred to stroke rehabilitation were
malnourished.
Tube feeding is considered a predictor for the development of aspiration pneu-
monia (Langmore et at, 1998). The reasons for this are as follows. Salivary flow
rate is reduced in the NBM patient due to the fact that food and Huids no longer
stimulate saliva production. This ?e'duction in saliva aow allows the coloniaation
of pathogenic organisms in the oral cavity. If these pathogenic orglnisLs are aspi-
rated, a chest infection is the likely outcome unless the patient's immune response
can deal with the organisms. However, if the immune funetion is compromised by
malnutrition, then the risk of infection is higher (Perry and McLaren,2003), In ad-
dition to this, note the previous discussions relating to disuse atrophy of muscles.
Without a reason to swallow (i.e. food and fluid intake), the individual has fewer op-
portunities to use these muscles in a functional context. The elderly population may
already be do-conditioned and thus at higher risk for malnutrition prior to hospitali-
zation. Further, dehydration and malnutrition cause reduced muscle strength, high
levels of fatigue, and reduced immunological function (Olde Rikkert and Rigaud,
2003) and therefore, a cycle of systematic decline. Consequently if the patient is suf-
(iciently alert, the clinician sheuld aim at providing activities to induce at least saliva
swallows (e.g. tastes of lemon ice or silcklng on a lollipop - see previous discussion).
The'move it or lose it'concept needs to be uppermost for the dysphagia clinician.
Note also the importance of good oral hygiene to reduce the likelihood of coloni-
zation of pathogenic oral bacteria. In a recent cost analysis study it was reported
that a single hospitalization for aspiration pneumonia presents an average cost of
US$6,000 (Waters et at,,2004), The dysphagia clinician should make every effort
to advocate for early nutrition and hydration, good oral hygiene, and short bursts of
rehabilitation treatment as soon as the patient is able to tolerate it. These strategies
may help reduce the likelihood of the development of aspiration pneumonia specifi-
cally due to nil oral status, which benefits the individual by improving quality of life
and potentially decreases morbidity and mortality (Waters et at.,2004). Thus rather
than waiting for the patient to improve, the clinician should actively treat the NBM
patient as early as possible to maximiEe recovery.
SUMMARY
This chapter discusses the importance of evidence-based practice for dysphagia re-
habilitation. It shows that the'evidence'for dysphagia rehabilitation is based on a
small number of studies that often have small sample sizes. Where evidence does
not exist, the clinician should ask whether the proposed treatment technique has
solid foundations that support a view that it'should'work. This chapter provided a
treatment style that is based on the principles underpinning exercise physiology and
motor learning in a functional context. Tt also highlighted the psychological issues
surrounding rehabilitation such as patient Insight, motivation and a?tive participa-
tion in goal-setting. Using a different approach to most texts, this chapter aimed to
provide clinicians with a starting point for functional rehabilitation ?f swallowing
function. It also described the role of feedback and biofeedback in .?ehabilitatio?.
Finally it concluded with discussions regarding the NBM patient. It is particularly
important that NBM patients receive every opportunity to participate in a rehabilita-
tion programme or modified rehabilitation programme to ensure that muscles used
in swallowing are not further depleted by disuse atrophy. Clinicians should read
this chapter together with Chapter 11 regarding compensation, as the majority of
patients, and particularly those with dysphagia of neurological origin will require
judicious use of both principles in achieving oral intake. Oral intake should be the
cliniciln's goal to maximize an individual's ability to participate in social activities
that are imperative for healthy physical, social, mental and psychological well-being.
Research into the field of rehabilitation of dysphagia is in its infancy and individu-
als and researchers are strongly encouraged to add to the evidence for its efficacy. It
will be prudent to liaise with experts in human movement studies to obtain the best
outcomes for our patients.
REFERENCES
Abernethy 3, Hanrahan SJ, Kippers V, Mckinnon LT, Pandy MG (2005) The Biophysical
Foundations of Human Movement (2nd edn). Lower Mitchum SA: Human Kinetics'.
Akner C, Decerholm T (2001) Treatment of protein-energy malnutrition in chronic non-
malignant disorders. American Journal of Clinical Nutrition 74: 6-24.
Aronson AE (1985) Clinical Voice Disorders: An Interdisciplinary Approach (2nd eOn). New
York: Thieme.
Barbui C (2005) Evidence-based medicine and medicine-based evidence. Neurological Sci-
ence 26 : 145-6.