a. What clinical tools should be used to detect the presence of dysphagia? Statements are based on core literature consisting of Class II [49, 50], III [6, 95] and IV [24, 27, 42, 48, 50–53, 85, 96, 97] level studies and expert opinion.  -PD patients with a positive screening for dysphagia should undergo an in-depth clinical swallowing examination by a speech-language pathologist with special training in swallowing disorders. If a speech-language therapist with an expertise in the evaluation of neurogenic dysphagia is not available on site, a referral pathway should be put in place.  -The clinical swallowing examination should include: 1) a thorough examination of cranial nerves; 2) the evaluation of dry swallows; 3) on-command and/or reflexive cough testing; 4) the evaluation of swallowing of various food and liquid consistencies; and 5) the detection of possible signs or symptoms of reduced swallowing efficiency and safety. Assessment of cognition and speech should always be carried out in conjunction with the clinical swallowing examination.  -In PD patients with motor fluctuations, the swallowing examination should be performed during an ON phase. In the presence of cervical-cranial dyskinesias, clinical evaluation should preferably be conducted during both phases (ON or OFF) to identify the safest moment for the patient to eat or drink. The clinical examination should not be performed during exacerbation periods of cervical-cranial dyskinesias interfering with the ability of feeding. -Meal observation, assessing a higher number of swallowing acts and including information on feeding dependency and meal duration, can provide valuable information on swallowing function. However, this is often not feasible in the outpatient setting. In these cases, we recommend gathering information about typical eating/drinking patterns and experiences by clinical history or questionnaires. - Patients with DBS implants should be tested in an ON medication phase with the stimulator turned ON. In case of a strong suspicious of detrimental effects of DBS on swallowing, the patient should be assessed in both conditions: with the stimulator turned ON and with the stimulator OFF. Assessment in both conditions should be performed after an adequate interval of time (generally several hours) to allow for the full array of motor and non-motor features to manifest. Different combinations of the DBS/medication states should be also tested in selected patients in which detrimental interactions between different DBS and medication states are suspected. b. What instrumental investigations should be used to detect the presence of dysphagia? Statements are based on core literature consisting of Class I [5, 98], II [62], III [23, 55, 61, 74, 75] and IV [20, 31, 56–59, 63–69, 73, 76, 77, 80, 82–84, 99–105] level studies and expert opinion. - When the clinical evaluation suggests the presence of dysphagia, patients should undergo an instrumental investigation for the assessment of swallowing. Depending on local availability and on specific advantages of each method, either FEES or VFSS are recommended as first-line diagnostic tools. - On suspicion of esophageal disorders, patients should be referred for further investigations such as upper gastrointestinal endoscopy, barium swallow, esophageal manometry, and/or acid- and reflux-related tests. - If impaired motility of the upper esophageal sphincter is suspected based on FEES or VFSS, pharyngo-esophageal manometry (possibly with the high-resolution modality) and/or electromyographic examination of the cricopharyngeal muscle should be considered. - The electrophysiological evaluation of oropharyngeal swallowing might provide further insights into the pathophysiological basis of dysphagia in PD and give useful clues for treatment.

c. How should severity of dysphagia be assessed?  In the literature, there are no validated scales specific for PD to rate dysphagia severity. The following statement is, therefore, entirely based on expert opinion. - Several scales exist to rate the severity of neurogenic dysphagia. The most widely used and available in multiple languages are PAS, FOIS and DOSS. PAS is based on imaging data, FOIS on clinical assessment, DOSS on both clinical and instrumental parameters.