Nutrition

Risk Factors for Dysphagia

The etiology of dysphagia in relation to acute cervical spinal cord injury is not completely understood. In addition to damaged nerves, the Consortium for Spinal Cord Medicine’s clinical practice guidelines on respiratory management following SCI (2005) has identified the following risk factors for dysphagia: supine position, spinal shock, slowing of gastrointestinal tract, gastric reflux, inability to turn the head to spit out regurgitated material, nausea inducing medications, recent anterior cervical spine surgery, presence of a tracheostomy, and age. Proper identification of risk factors in individuals at risk of dysphagia, can allow for early dietary intervention that could prevent secondary complications.

Author Year

Country

Research Design

Sample Size

 Methods Outcomes

Ihalainen et al. 2017

Finland

Prospective Cohort

N=37

Population: Mean age: 61.2 yr; Gender: males=31, females=6; Injury etiology: Sport=2, Transport=6, Fall=28, Unknown=1; Level of injury: C1-C4=32, C5-C8=4, Unknown=1; Level of severity: AIS A=8, AIS B=3, AIS C=5, AIS D=21; Mean time since injury: 16.4 days.

Intervention: Clinical swallowing trial and Videofluoroscopic Swallowing Study (VFSS) to identify laryngeal penetration or aspiration.
Outcome Measures: Rosenbek’s Penetration-Aspiration Scale (PAS), risk factors for laryngeal penetration or aspiration.

1.     Results of the PAS divided patients into two groups: penetrator/aspirators (n=19) and non-penetrator/aspirators (n=18).

2.     The two groups were significantly different in necessity for bronchoscopy (p=0.042), coughing (p=0.007), and changes in voice quality (p=0.004).

Shem et al. 2012

USA

Prospective Cohort

N=40

 Population: Mean age: 41.0 yr; Gender: males=31, females=9; Injury etiology: Motor vehicle accident=9, Fall=7, Gunshot wound=3, Diving=6, Bicycle accident=4, Motorcycle accident=2, Other=9; Level of injury: C4 or higher=29, C3 or lower=11; Level of severity: Not reported; Mean time since injury: 14.3 days.
Intervention: Presence of dysphagia was determined in patients using a Bedside Swallowing Examination (BSE), and a Videofluoroscopy Swallow Study (VFSS).
Outcome Measures: Risk factors for dysphagia, medical complications resulting from dysphagia. 

1.     Significant risk factors for dysphagia included: age (p=0.016), tracheostomy tube (p=0.013), mechanical ventilation (p=0.003), and nasogastric tubes (p=0.027).

2.     There was a trend towards significance for halo vest usage as a risk factor (p=0.076).

3.     In terms of medical complications, individuals with dysphagia have significantly higher occurrences of pneumonia (p=0.004).

4.     There was a statistical trend for longer length of stays for individuals with dysphagia (p=0.064), and days to BSE was marginally significant (p=0.047).

Shem et al. 2012b

USA

Prospective Cohort

N=39

 Population: Mean age: 41.6 yr; Gender: males=30, females=9; Injury etiology: Motor vehicle accident=9, Fall=7, Gunshot wound=3, Diving=6, Bicycle accident=4, Motorcycle accident=2, Other=8; Level of injury: C4 or higher=28, C3 or lower=11; Level of severity: Not reported; Mean time since injury: 14.1 days.
Intervention: Presence of dysphagia was determined in patients using a Bedside Swallowing Examination (BSE), and a Videofluoroscopy Swallow Study (VFSS). Sensitivity and specificity of the BSE was determined in reference to the VFSS.
Outcome Measures: Risk factors for dysphagia, medical complications resulting from dysphagia. 

1.     Dysphagia diagnosis was significantly associated with: mechanical ventilation (p=0.005), presence of pneumonia (p=0.007), older age (p=0.015), a tracheostomy (p=0.019), a nasogastric tube (p=0.023), and a greater length of stay (p=0.023).

2.     There was a trends towards significance for halo vest use as a risk factor (p=0.066), and days to BSE (p=0.068) as a complication.

Shem et al. 2011

USA

Prospective Cohort

N=29

 Population: Mean age: 41.0 yr; Gender: males=22, females=7; Injury etiology: Motor vehicle accident=5, Fall=7, Gunshot wound=3, Diving=3, Bicycle accident=3, Motorcycle accident=3, Other=5; Level of injury: C1=1, C2=3, C3=7, C4=10, C5=4, C6=2, C7=2; Level of severity: Not reported; Mean time since injury: 12.9 days.
Intervention: Presence of dysphagia was determined in patients using a Bedside Swallowing Examination (BSE), and a Videofluoroscopy Swallow Study (VFSS).
Outcome Measures: Risk factors for dysphagia, medical complications resulting from dysphagia. 

1.     Significant risk factors for dysphagia included: age (p=0.028), presence of a tracheostomy (p=0.047), and use of a nasogastric tube (p=0.029).

2.     Non-significant risk factors included: presence of a halo vest (p=0.081), posterior spine surgery (p=0.090), anterior spine surgery (p=0.82), gender (p=0.43), presence of a head injury (p=0.26), high versus low tetraplegia (p=0.79), complete injury (p=0.30) and presence of a collar (p=0.97).

3.     Individuals with dysphagia had significantly higher occurrences of pneumonia (p=0.016).

4.     As well for individuals with dysphagia, complications that trended towards significance included: need for bronchoscopy (p=0.054) and length of stay (p=0.064).

Shin et al. 2011

Korea

Retrospective Cohort

N=121

 Population: Mean age: 44.9 yr; Gender: males=105, females=16; Injury etiology: Motor vehicle accident=81, Fall=26, Diving=4, Other traumatic=7, Non-traumatic=3; Level of injury: Cervical SCI; Level of severity: AIS A=72, AIS B=20, AIS C=19, AIS D=10; Mean time since injury: 178.35 days.
Intervention: Presence of dysphagia/aspiration was determined using Videofluoroscopy Swallow Study (VFSS).
Outcome Measures: Aspiration prevalence, risk factors for aspiration.

1.     VFSS found aspiration in 10 patients.

2.     Aspirators compared to non-aspirators were significantly older in age (p=0.044).

3.     Aspiration was more common for patients with tracheostomy (p=0.011).

4.     Significantly higher incidences of aspiration were found for patients with symptoms of dysphagia (p=0.002) and signs of dysphagia (p=0.001).

Seidl et al. 2010

Germany

Retrospective Cohort

N=175

 Population: Mean age: 43.5 yr; Gender: males=144, females=31; Injury etiology: Fracture 1 vertebral body=73, Fracture 2 vertebral bodies=47, Fracture >2 vertebral bodies=16, Spondylodiscitis=15, Contusio spinalis=10, Tumour=5, Spinal stenosis=4, Nuclear pulposus prolaps=3, Knife wound=1, Postoperative=1; Level of injury: C0=1, C1=1, C2=4, C3=14, C4=58, C5=53, C6=33, C7=6, C8=5; Level of severity: Frankel A=103, Frankel B=19, Frankel C=21, Frankel D=24, Frankel E=8; Time since injury: Participants were recruited within 8 wk of their injury.
Intervention: Swallowing ability was examined with a clinical bedside bolus-swallowing test by a speech therapist, and an endoscopic-swallowing test.
Outcome Measures: Risk factors for dysphagia.

1.     Swallowing disorders were most common in patients with the highest grade of sensorimotor deficit, however this was not significant (p>0.05).

2.     Posterior and combined approach surgery patients had a non-significant higher rate of swallowing disorders (p>0.05).

3.     Swallowing disorders increased significantly with lower levels of tetraplegia (p<0.05), tracheotomies (p<0.05), and duration of ventilation (p<0.05).

Brady et al. 2004

USA

Case Control

N=131

 Population: Dysphagia Group (n=72): Mean Age=55.5yr; Gender: Male=13, Female=59; Type of Injury: Traumatic injury (66.4%), Non-traumatic (30.6%); Respiratory Status: Tracheotomy tube=24; Type of Cervical Spine Surgery: Anterior=31, Posterior=11, Combined=10, None=20.
Non-Dysphagia Group (n=59): Mean Age=55.9yr; Gender: Not Reported; Type of Injury: Traumatic=40, Non-traumatic=19; Respiratory Status: Tracheotomy tube=6; Type of Cervical Spine Surgery: Anterior=14, Posterior=18, Combined=4, None=23.
Intervention: Chart reviews were conducted on patients admitted to two rehabilitation hospitals within a 27mo period. All patients were screened for dysphagia upon admission. Those clinically suspected of experiencing dysphagia were referred for further evaluation with a speech-language pathologist.
Outcome Measures: American Speech-Language-Hearing Association National Outcomes Measurement swallowing level scale (ASHA NOMS), type of surgery, respiratory status. Reviewed data had been collected at admission and at discharge from rehabilitation.

1.     The presence of a tracheostomy tube to assist the patient was significantly predictive of the occurrence of dysphagia (p=0.002) with one in three dysphagic patients having had a tracheostomy inserted compared to one in ten non-dysphagic patients.

2.     There was a significant difference between the two groups concerning the type of surgery. Dysphagic patients were significantly more likely to have undergone cervical surgery, particularly the anterior approach, compared with the non-dysphagic patients (p=0.02). 43.1% of patients with dysphagia underwent anterior approach surgery.

3.     ASHA NOMS scores at discharge revealed that the presence of a tracheostomy tube (p=0.02), receiving fewer days of treatment (p=0.04) and demonstrating aspiration (p=0.0001) were negative predictors of dysphagia recovery.

Kirshblum et al. 1999

USA

Case Control

N=187

 Population: Mean age: 44.3 yr; Gender: males=156, females=31; Injury etiology: Fall=64, Motor vehicle accident=65, Gunshot wound=9, Diving=31, Other=18; Level of injury: C7 and below=15, C6=21, C5=43, C4=63, C3=25, C2 and above=20; Level of severity: AIS A=71, AIS B=5, AIS C=59, AIS D=48, AIS E=4; Median time since injury: 30 days (range: 5-264 days).
Intervention: Videofluoroscopic Swallowing Study (VFSS) to confirm the presence of dysphagia.
Outcome Measures: Risk factors for dysphagia. 		 1.     Significant predictors for dysphagia included: older age (p=0.028), history of tracheostomies (p<0.0001), ventilator status (p<0.001), anterior approach cervical spine surgery (p=0.016), higher level injuries (p=0.012), and ASIA impairment classification (p=0.02).
Hayashi et al. 2017
Japan
Retrospective case series
N=298		 Population: Median age: 64.0 yr; Gender: males=256, females=42; Level of injury: C3-C7; Level of severity: AIS A=98, AIS B=38, AIS C=127, AIS D=35; Time since injury: approximately 3 days.
Intervention: Retrospective review of patients with acute cervical spinal cord injury for presence of dysphagia or not. Suspected associated risk factors for dysphagia were also recorded and put into a multivariable logistic regression.
Outcome Measures: Risk factors for dysphagia.		 1.     Multivariable logistic regression analyses revealed that the following were significant risk factors for dysphagia: age greater than 72 yr (p=0.02), AIS A or B (p=0.008), and presence of a tracheostomy (p<0.001).

Shem et al. 2005

USA

Case Series

N=68

Population: Mean Age=33yr; Severity of Injury: ASIA A=36, ASIA B=7, ASIA C=12, ASIA D=13; Level of Injury: C2=1, C3=11, C4=56; Mean Time Post-Injury=8.8d.

Intervention: Chart reviews were conducted on patients’ medical records existing on the SCI National Database and were admitted to acute inpatient rehabilitation between 1998 and 2002. Data collected upon patient admission was analysed for contributing risk factors and predictors of dysphagia.

Outcome Measures: Bedside Swallow Evaluation, type of surgery, presence of tracheostomy, ventilator status.

1.     Although patients who also underwent cervical fusion surgery reported more cases of dysphagia and a longer mean time returning to a regular diet, cervical fusion was not a statistically significant risk factor for dysphagia.

2.     Patients who had been intubated with a tracheostomy tube demonstrated a higher incidence of dysphagia than patients that did not receive a tracheostomy tube (p=0.0002).

3.     Furthermore, patients with a tracheostomy tube took a significantly longer amount of time returning to their regular diet than non-tracheostomy patients (p<0.0001).

4.     Patients who required ventilator support were also significantly more likely to experience dysphagia post-surgery (p=0.04) and took significantly longer to return to regular diet (p=0.0083).

5.     The use of a Halo Skeletal Fixator was not significantly associated with diagnosis of dysphagia or mean time to eating a regular diet.

Chaw et al. 2012

USA

Observational

N=68

 Population: Mean age: 43.0 yr; Gender: males=57, females=11; Injury etiology: Motor vehicle accident=18, Fall=13, Diving=9, Bicycle accident=5, Gunshot wound=5, Motor cycle accident=4, Medical=4, Myelopathy=4, Trauma=4, Other=2; Level of injury: C1=2, C2=6, C3=14, C4=6, C4 (incomplete)=21, C5 (incomplete)=10, C6 (incomplete)=4, C7 (incomplete)=3, C8 (incomplete)=2; Level of severity: Complete=28, Incomplete=40; Mean time since injury: 31.8 days.
Intervention: Bedside Swallowing Examination (BSE), which was followed by Videofluoroscopy Swallow Study (VFSS) within 72 hr.
Outcome Measures: Risk factors for dysphagia.

1.     Risk factors that were significantly related to dysphagia included: ventilator status (p=0.012), presence of tracheostomy (p=0.028), and use of a NG tube (p=0.049). Other risk factors were non-significant (p>0.05).

2.     Individuals with dysphagia had significantly higher occurrences of pneumonia (p<0.001).

3.     There were no significant differences between those with and without dysphagia on: bronchoscopy need (p=0.23), rate of re-intubation (p=0.14) or length of stay (p=0.087).
Abel, Ruf & Spahn 2004

Germany

Observational

N=73

Population: Mean age: 42.9 yr; Gender: males=51, females=22; Injury etiology: Trauma=56, Spondylitis=5, Tumour=3, Other=9; Level of injury range: C1-C7; Level of severity: AIS A (complete)=41, incomplete=32; Mean time since injury: Not reported.

Intervention: Patients with cervical SCI admitted to an initial care facility between January 1997 to December 2000. Prevalence of pneumonia via x-rays, and dysphagia via methylene blue test and videofluoroscopic swallowing, were determined at intake and discharge. Changes in dysphagia status were observed after tracheostomies, surgery to the cervical spine and dietary restrictions.
Outcome Measures: Risk factors for dysphagia.

1.     Patients with higher levels of cervical injury are more significantly likely to have a swallowing disorder (p<0.05).

2.     Tracheostomy was strongly associated with the incidence of dysphagia (p=0.00014).

3.     Anterior spinal surgery did not result in a significant contribution to dysphagia (p=0.42).

4.     Patients with oral phase problems required dietary modifications at a significantly higher rate than those with problems in the pharyngeal phase (p=0.044).

5.     At discharge, 9/26 cases had their dysphagia resolved.

Discussion

Several risk factors have been associated with dysphagia incidence in individuals with SCI. Risk factors commonly identified were presence of a tracheostomy, ventilator use, age, nasogastric tube use, level of cervical injury, and presence of pneumonia.

Tracheostomies appear to be the most common factor for dysphagia. Tracheostomy tubes are used in individuals with SCI to facilitate ventilation and impaired cough reflexes (Shem et al. 2011). Prolonged use of tracheostomy tubes reduces respiratory volume and subglottic pressure inadvertently increasing the risk of aspiration (Hayashi et al. 2017). Aspiration can also occur due to leakage of secretions around the cuff depending on how well the tracheostomy tube is sealed (Chaw et al. 2012). The utilisation of a tracheostomy tube may have a disruptive presence on motor and sensory functioning with aspiration potentially caused by glottis injury, loss of protective reflexes, fixation of the trachea to the anterior neck skin, and esophageal obstruction due to the cuff’s contact with the esophagus and hypopharynx (Kirshblum et al. 1999). Shem et al. (2011) also point out that the poor secretion is a risk factor for both pneumonia and dysphagia and this is managed with tracheostomy tubes; therefore, the connection between dysphagia and tracheostomy tubes may be better explained through management of secretion difficulties.

Ventilator use was also a frequent risk factor for dysphagia. There exists a multitude of ventilation techniques all with goal of assisting in respiration and secretion management to simulate coughing (Wong et al. 2012). Chaw et al. (2012) explain that confirming a causal relationship between dysphagia and ventilator dependence and/or tracheostomy is difficult due to the latter’s link with pneumonia and as such, patients may require greater intensive intervention in order to improve their health. This assertion is supported by Wong et al. (2012) who stated that with aspiration and pneumonia being major complications of dysphagia, the need for ventilator support increases. This in turn complicates directionality as to the definitive cause of dysphagia with ventilator support and pneumonia acting as both independent and interrelated risk factors.

Age has been identified as risk factor for many diseases and conditions. Age is believed to increase the risk of dysphagia because increasing age is associated with changes in the physiology of the upper esophageal sphincter and pharyngeal region, blunting individuals’ sensation and motility during the swallowing reflex (Hayashi et al. 2017).

Nasogastric tubes are used for acute SCI for gastrointestinal decompression. The nasogastric tubes impede swallowing as it traditionally passes through the lumen of the pharynx. Nasogastric tubes can consequently lead to aspiration as they: lower the anatomical integrity of the upper and lower esophageal sphincters, increase the frequency of transient lower esophageal sphincter relaxations, and lead to a desensitization of the pharyngoglottal adduction reflex (Chaw et al. 2012).

The consortium guidelines should be updated to reflect these more commonly identified risk factors present in the literature.

Conclusion

There is level 5 evidence (from several observational studies: Hayashi et al. 2017, Chaw et al. 2012, Shem et al. 2012, Shem et al. 2012b, Shem et al. 2011, Shin et al. 2011, Seidl et al. 2010, Shem et al. 2004, Abel, Ruf & Spahn 2004, Brady et al. 2004, Kirshblum et al. 1999) that presence of a tracheostomy is a risk factor for dysphagia in individuals with SCI.

There is level 5 evidence (from six observational studies: Chaw et al. 2012, Shem et al. 2012, Shem et al. 2012b, Shem et al. 2011, Seidl et al. 2010, Shem et al. 2004) that ventilator use is a risk factor for dysphagia in individuals with SCI.

There is level 5 evidence (from six observational studies: Hayashi et al. 2017, Shem et al. 2012, Shem et al. 2012b, Shem et al. 2011, Shin et al. 2011, Kirshblum et al. 1999) that increasing age is a risk factor for dysphagia in individuals with SCI.

There is level 5 evidence (from four observational studies: Chaw et al. 2012, Shem et al. 2012, Shem et al. 2012b, Shem et al. 2011) that presence of nasogastric tubes are a risk factor for dysphagia in individuals with SCI.

Several risk factors for dysphagia in individuals with SCI exist, the most common being presence of a tracheostomy, ventilator use, increasing age, and presence of a nasogastric tube.

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