Parkinson Disease Affects Peripheral Sensory Nerves in the Pharynx

J Neuropathol Exp Neurol. 2013 Jun 13. [Epub ahead of print]

Mu L, Sobotka S, Chen J, Su H, Sanders I, Nyirenda T, Adler CH, Shill HA, Caviness JN, Samanta JE, Sue LI, Beach TG; the Arizona Parkinson’s Disease Consortium.

Source

Upper Airway Research Laboratory, Department of Research, Hackensack University Medical Center, Hackensack, New Jersey (LM, SS, JC, HS, TN); Department of Neurosurgery, Mount Sinai School of Medicine, New York, New York (SS); Alice and David Jurist Institute for Biomedical Research, Hackensack University Medical Center, Hackensack, New Jersey (IS); Parkinson's Disease and Movement Disorders Center, Mayo Clinic Arizona, Scottsdale, Arizona (CHA, JNC); Cleo Roberts Center for Clinical Research, Banner Sun Health Research Institute, Sun City, Arizona (HAS); Banner Good Samaritan Medical Center, Phoenix, Arizona (JES); and Civin Laboratory for Neuropathology, Banner Sun Health Research Institute, Sun City, Arizona (LIS, TGB).

Abstract

Dysphagia is very common in patients with Parkinson disease (PD) and often leads to aspiration pneumonia, the most common cause of death in PD. Current therapies are largely ineffective for dysphagia. Because pharyngeal sensation normally triggers the swallowing reflex, we examined pharyngeal sensory nerves in PD patients for Lewy pathology.Sensory nerves supplying the pharynx were excised from autopsied pharynges obtained from patients with clinically diagnosed and neuropathologically confirmed PD (n = 10) and healthy age-matched controls (n = 4). We examined the glossopharyngeal nerve (cranial nerve IX), the pharyngeal sensory branch of the vagus nerve (PSB-X), and the internal superior laryngeal nerve (ISLN) innervating the laryngopharynx. Immunohistochemistry for phosphorylated α-synuclein was used to detect Lewy pathology. Axonal α-synuclein aggregates in the pharyngeal sensory nerves were identified in all of the PD subjects but not in the controls. The density of α-synuclein-positive lesions was greater in PD patients with dysphagia versus those without dysphagia. In addition, α-synuclein-immunoreactive nerve fibers in the ISLN were much more abundant than those in cranial nerve IX and PSB-X. These findings suggest that pharyngeal sensory nerves are directly affected by pathologic processes in PD. These abnormalities may decrease pharyngeal sensation, thereby impairing swallowing and airway protective reflexes and contributing to dysphagia and aspiration.