Evaluation of the Results of Combined Medical and Swallowing Behavioral Readjustment Therapy in Oropharyngeal Dysphagia Management Among Parkinson's Patients

Parkinson's disease is the second most common neurodegenerative disorder with an estimated prevalence of 6.1 million individuals all over the world.

Parkinson's disease is characterized by motor features such as tremor, rigidity and bradykinesia, and several non-motor features such as dysphagia, autonomic dysfunction, sleep disorders, cognitive impairment, depression, and psychosis that may occur at any time during the disease course, but become more frequent with advanced disease. Dysphagia in Parkinson's disease is a manifestation of swallowing dysfunction that may involve oral, pharyngeal or esophageal phases of swallowing and may be present in every stage of the disease. Indeed, even though swallowing disorders become apparent mostly in the advanced stage of Parkinson's disease, they may already be present in the early stages, when they often go undetected.

The mechanism of dysphagia in Parkinson's disease is unclear. Studies have shown that in the progression of Parkinson's disease, a variety of pathological changes occur in the neuromuscular associated with swallowing function, resulting in impaired central and peripheral swallowing regulation mechanisms, and eventually swallowing disorders (.Both dopaminergic and non-dopaminergic mechanisms can be involved in dysphagia pathophysiology of parkinsonian syndromes In this regard, bradykinetic swallowing abnormalities, related to the nigrostriatal dopamine deficiency, are commonly observed as early findings of dysphagia in these disorders.

Parkinson's disease can impair all phases of swallowing. Dysphagia in the oral phase of Parkinson's disease patients is characterized by difficulties in the initiation of swallow, oral residues, piecemeal swallow and premature falling of the food; the pharyngeal phase is characterized by regurgitation of food into the nasal cavity or upper pharynx, pharyngeal residue and penetration/aspiration, and the esophageal phase is characterized by reduced esophageal peristalsis. Another distinctive feature in parkinsonian syndromes is the incomplete or absent relaxation of the cricopharyngeal muscle during the pharyngeal phase of swallowing, as possible consequence of brainstem involvement mostly in the advanced stages .Also there is recent evidence suggesting that time-to-laryngeal vestibule closure and airway responses to penetrated material are impacted by Parkinson's disease , greater evidence is needed to elucidate those physiological impairments for which treatment might have the greatest impact for swallowing safety and efficiency .

Treatments of dysphagia in Parkinson's disease include pharmaceutical, rehabilitation approaches and surgical . Pharmaceutical treatment is usually performed by the prescription of different dopaminergic medication ( levodopa, carbidopa , apomorphine , domperidone , and rotigotine . The effects of pharmaceutical treatment on improving motor functions of patients with Parkinson's disease are well demonstrated. However, contradictory results are reported on the effectiveness of pharmaceutical treatment on the swallowing function of patients with Parkinson's disease . As it has been suggested for many years that swallowing dysfunction is not related to nigrostriatal dopamine deficiency and may have a non-dopaminergic influence. Also there is botulinum toxin therapy which is new technique in patients who have well documented upper esophageal sphincter impairment . Another technique is botulinum toxin injection in parotid glands which leads to decrease sialorrhoea in patients with Parkinson's disease, but it has no effect on improving the swallowing function .