Methods
Results
Level of evidence | Data analysis | Ref. | Subjects Hoehn & Yahr scale (H-Y) | Treatment(s) groups | Evaluation techniques Outcome parameters [ON/OFF motor phase] | Author(s)’ conclusions |
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Rehabilitative treatment(s)
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1. B (nonrandomized clinical trial) | Statistical analysis (analysis of variance) | [15] | N = 8 | Lee Silverman Voice Treatment (LSVT) | Videofluoroscopy of swallowing Outcome parameters: • Identification of physiologic oropharyngeal motility disorders • Timed variables of swallowing • Oropharyngeal swallow efficiency Blinded judgment [the same time of day and medicine cycle for each patient] | The incidence of the swallow motility disorders is consistently reduced after LSVT and some timed variables of swallowing improve significantly. Findings suggest that LSVT may activate neuromuscular control of the entire aerodigestive tract, improving function in both the oral tongue and the tongue base during the oral and pharyngeal stages of swallowing. |
H-Y: II-IV | ||||||
2. B (nonrandomized clinical trial) | Statistical analysis (Wilcoxon signed rank test) | [4] | N = 10 H-Y: III (N = 8) and IV (N = 2) | 1. Five exercises: range of tongue motion exercises, resistance exercises, exercises to increase the adduction of vocal folds, Mendelsohn maneuverrange of motion exercises in the neck, trunk, and shoulder joints. | Electromyography (EMG) Outcome parameter: • Premotor time (PMT) [ON motor phase] | After swallowing training, the PMTs in the patients with PD decrease significantly, even if the training is given only once. Swallowing training can improve the initiation of the swallowing reflex in patients with PD and dysphagia. |
3. B (nonrandomized clinical trial) | Statistical analysis (paired t test) | [16] | N = 12 H-Y: II-V | Verbal cueing while presenting a spoon to the mouth | Exeter Dysphagia Assessment Technique (EDAT): nasal airflow, contact of the lips/tongue with a spoon, recording of sounds associated with swallowing. Outcome parameters: • Direction of respiration immediately preceding and following each swallow • Number of swallows • Duration of the “oral part” • Duration of the “pharyngeal part”[ON motor phase] | Verbal cueing results in a significant reduction in the duration of the oral part but has no impact on the duration of the pharyngeal part of or the mean number of swallows. The use of the verbal cue improves the oral and lingual bradykinesia. |
4. B (nonrandomized clinical trial) | Statistical analysis (analysis of variance, Kruskal-Wallis) | [17] | N = 10 H-Y: II-III | Bolus modification (thin liquid and pudding-thick boluses): single session | Videofluoroscopy of swallowing Outcome parameters: • Timed variables of swallowing • Qualitative variables of swallowing (P-A scaleh, tongue pumps). Blinded to patients’ identity[ON motor phase] | Analysis reveals significant differences between oral transit time, number of tongue pumps, and P-A scale with respect to bolus consistency. Oral transit time and the number of tongue pumps increase with thicker boluses, P-A score is higher for thinner boluses. No significant differences are found for pharyngeal transit time. |
5. B (nonrandomized clinical trial) | Descriptive statistics | [7] | N = 228 PD H-Y: I-V | Bolus modification (honey-thick, nectar-thick), postural changes (chin down): single session | • Videofluoroscopy of swallowing Outcome parameter: Qualitative variable of swallowing (aspiration) | 39% of all participants aspirate on all three interventions. 12% aspirate on two of the three interventions. 17% aspirate on one of the three interventions. 32% aspirate on none of the three interventions. |
Surgical treatment(s)
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6. C (consensus or expert opinion) | [19] | N = 4 | Cricopharyngeal myotomy (Zenker’s diverticulectomy) | Videoesophagographya
Esophageal manometrya
| All four patients have experienced excellent and sustained relief of esophageal symptoms following surgery, providing further support for the primacy of cricopharyngeal dysfunction in causing dysphagia in these patients. The patients tolerate myotomy extremely well and none developed aspiration. | |
7. C (consensus or expert opinion) | [20] | N = 3 H-Y: II-IV | Cricopharyngeal myotomy (Zenker’s diverticulectomy) | Videoesophagographya
Esophageal manometrya
| Three patients with cricopharyngeal dysfunction have undergone cricopharyngeal myotomy with excellent results. | |
Pharmacologic treatment(s)
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8. B (nonrandomized clinical trial) | Statistical analysis (Wilcoxon signed rank test) | [21] | N = 18 | Maximum tolerated doses of L-dopa (range = 1-6.8 g per day) versus a placebo at different moments in the same patients. | Lateral cineradiographiesb of swallowing Outcome parameters: • Timed variables of swallowing (duration of pharyngeal deglutition) Blinded to therapy | Although 11 patients complain of difficulty in feeding, their radiologic pattern of deglutition is remarkably normal before treatment. L-dopa fails to effect any clinical improvement. Probably dysphagia in our patients arises from a disturbance occurring before or after pharyngeal deglutition. |
9. B (nonrandomized clinical trial) | Statistical analysis (Wilcoxon signed rank test, paired t test) | [22] | N = 15 | After withholding antiparkinsonian medications for a minimum of 8 h, 250 mg levodopa plus 25 mg carbidopa is administered orally on the first day. Subcutaneous apomorphine (mean dose 3.5 mg) is administered 1 week later, following the same sequence. | MBSOutcome parameters: • Qualitative variables of swallowing • Timed variables of swallowing Blinded judgment (to schedule of medication)[Pretreatment MBS off][Posttreatment MBS on] | For qualitative variables, few significant differences are found after levodopa or apomorphine. A reduction in oral preparatory phase time with semisolids and thin fluids after levodopa is observed as well as reduction in the pharyngeal transit time with semisolids after apomorphine. Swallowing dysfunction is predominantly resistant to dopaminergic stimulation. |
10. B (nonrandomized clinical trial) | Statistical analysis (paired t test) | [23] | N = 28 H-Y: mean 2.8–3 | G1: “Banxia Houpo Tang” (BHT) 3 × 1.5 g/day for 4 weeks, 30 min before each meal (N = 22 PD)G2: lactate 3 × 1.5 g (N = 6 PD) | Submental EMG Outcome parameter: • Timed variables of swallowing (latency time of the swallowing reflex = timing from the injection of the bolus to the onset of swallowing) Blinded to therapy | Despite all patients having long-term levodopa therapy, the traditional Chinese medicine improves the swallowing reflex in the Parkinson patients significantly. Mechanisms of this improvement are unknown. |
11. B (nonrandomized clinical trial) | Statistical analysis (paired t test, McNemar tests) | [24] | N = 10 H-Y: I-IV | After withholding antiparkinsonian medication for at least 12 h, the usual dose of levodopa is administered. | SWAL-QOLa
EMG with nasal cannula FEES Outcome parameters: • Coordination of swallow and respiration • Timed variables of swallowing • Qualitative variables of swallowing (visuoperceptual) | Swallowing efficiency may be reduced with levodopa medication. No association is found between levodopa and coordination of swallowing and respiration, laryngeal penetration, or tracheal aspiration, indicating that the risk of aspiration may remain unchanged. It is speculated that levodopa therapy might actually reduce swallowing efficiency while keeping the risk of aspiration unchanged in patients with PD. |
12. B (nonrandomized clinical trial) | Statistical analysis and descriptive statistics (Wilcoxon signed rank test) | [26] | N = 8 H-Y: mean 3.1 (I-V) | Subcutaneous apomorphine (0.05 mg/kg) injection (combined with domperidone) after withholding antiparkinsonian medications overnight (12 h) | Buccolinguofacial motor function test Videofluoroscopy of swallowing Outcome parameters: • Qualitative variables of swallowing. • Timed variables of swallowing (swallowing stage durations) [Pretreatment videofluoroscopy off] [Posttreatment videofluoroscopy on] | Central dopaminergic stimulation by apomorphine improves swallowing abnormalities and total swallowing time in a subgroup of patients with PD and swallowing disorders. This improvement seems to be correlated mainly with improvement of early stages of swallowing and improvement of the buccolinguofacial motor score. However, the significant interindividual variations and differential effects on the various swallowing stages must be investigated in more patients. |
13. B (nonrandomized clinical trial) | Descriptive statistics | [27] | N = 15 H-Y: I-IV | G1: Levodopa: intake of a subject’s usual dose of levodopa after withholding antiparkinsonian medications overnight. (> 8 h) (N = 15)G2: Therapeutic maneuvers (N = 3) | MBS Outcome parameters: • Swallowing behaviors (mastication, bolus formation, oral stasis, lingual peristalsis, tongue movements, etc.) [Pretreatment MBS off] [Posttreatment MBS on] | G1: 5/15 patients with abnormal swallows show improvement in swallowing following an oral dose of levodopa. The degree of improvement ranges from mild to dramatic. Transit times for thick boluses show the greatest improvement. Higher doses of levodopa do not provide additional benefit.G2: The voluntary airway protection technique eliminates aspiration in 2/3 patients. |
14. B (nonrandomized clinical trial) | Descriptive statistics | [28] | N = 12–15? H-Y: mean 1.9 | 200 mg levodopa (in combination with 50 mg benserazide) orally | MBS Outcome parameters: • Timed variables of swallowing • Qualitative variables of swallowing [Pretreatment MBS off] [Posttreatment MBS on] | More than half of the patients experience improved swallowing function after levodopa treatment due to a reduction of bradykinesia and rigidity of the tongue. Aspiration is found in 3 patients. Two of these 3 patients reveal no post-levodopa aspiration. The dopaminergic mechanism may play a role in oropharyngeal control of swallowing. |
Other treatment(s)
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15. B (nonrandomized clinical trial) | Descriptive statistics | [29] | N = 3 H-Y: III | Mandibular implant overdentures | Modified symptom questionnaire on gastrointestinal (GI) symptoms by Horrowitz et al. (4-point scale: 0 = none, 3 = severe complaints). Body weight (kg) Self-rating scale for chewing abilitiesb
| On the gastrointestinal scale, all patients have improved from a mean score of 8.7 to 5.7 despite a general deterioration of the PD scores during follow-up. The implant-prosthodontic treatment increases chewing ability and appears to enhance oropharyngeal predigestion. |
16. C (consensus or expert opinion) | [31] | N = 4 | Percutaneous injection of botulinum neurotoxin type A in the cricopharyngeal muscle | Clinical examination Videofluoroscopy of swallowing (visuoperceptual rating?) Electromyography | Given its safety and effectiveness, the authors propose that treatment with botulinum neurotoxin type A may be a successful alternative to invasive procedures or may be a useful tool for identifying patients who might benefit from surgical myotomy. |