Cutaneous Autonomic Pilomotor Testing to Unveil the Role of Neuropathy Progression in Early Parkinson's Disease
Condition: Parkinson's Disease
MeSH terms: Parkinson Disease
Study type: Observational

Summary: 
      In Parkinson's disease (PD), alpha-synuclein accumulation in cutaneous autonomic pilomotor
      and sudomotor nerve fibers has been linked to autonomic nervous system disturbances even in
      the early stages of the disease. The investigators recently introduced a non-invasive
      technique to assess autonomic adrenergic fiber function using the quantitative pilomotor
      axon-reflex test (QPART). In the present study the investigators aim to assess the
      association between alpha-synuclein mediated structural autonomic nerve fiber damage and
      nerve function in PD, elucidate the role of neuropathy progression during the early disease
      stages, and test reproducibility and external validity of pilomotor function assessment using
      quantitative pilomotor axon-reflex test (QPART) and sudomotor function via quantitative
      direct and indirect test of sudomotor function (QDIRT).

      A prospective controlled study will be conducted in four sites (Dresden, Germany; Berlin,
      Germany; Budapest, Hungary; Boston, USA). A total of 52 male and female patients with
      idiopathic PD (Hoehn&Yahr 1-2) and 52 age- and sex-matched healthy controls will be
      recruited. Pilomotor function will be evaluated after iontophoresis of phenylephrine on the
      dorsal forearm to elicit a cutaneous axon-reflex mediated response (goosebumps). Silicone
      impressions of the stimulated area will be obtained, scanned and quantified for pilomotor
      muscle impressions by number, impression size and area of axon-reflex pilomotor erection
      spread. Sudomotor function will be evaluated after axon-reflex stimulation via iontophoresis
      of acetylcholine on the dorsal forearm. Stained sweat droplets will be captured using
      repeated digital photography and will be quantified over time for droplet number and
      axon-reflex spread. Sympathetic skin responses following deep inspiration will be analyzed
      using skin conductance quantification. Testing and evaluation of autonomic and motor symptoms
      will be performed at baseline, after 2 weeks, 1 year, 2 years and 3 years. Skin biopsies will
      be obtained at baseline and after 3 years and will be analyzed for nerve fiber density and
      alpha-synuclein accumulation.

      The investigators expect that this study will unveil whether progression of autonomic nerve
      dysfunction assessed via pilomotor and sudomotor axon-reflex tests is related to progression
      of autonomic symptom severity and alpha-synuclein deposition in PD. Additionally, potential
      applications of the used techniques include interventional studies evaluating
      disease-modifying approaches and clinical assessment of autonomic dysfunction in patients
      with PD.
    

Detailed description: 
      PURPOSE OF THE PROTOCOL With the goal of developing novel endpoints for early stage trials of
      disease modifying therapies in Parkinson's disease (PD) the objective of this study is to a)
      assess reproducibility b) external validity and reliability c) to perform a longitudinal
      assessment of sudomotor (QDIRT) and pilomotor (QPART) responses in early PD patients.

      Moreover, this study aims to assess the hypothesis that functional impairment in pilomotor
      and sudomotor nerve fibers in early PD correlates with a-synuclein deposition mediated
      structural fiber damage and may therefore constitute a potential non- invasive biomarker for
      autonomic involvement in PD.

      BACKGROUND In skin biopsy studies of PD, alpha-synuclein accumulation in cutaneous autonomic
      nerve fibers has been linked to autonomic nervous system disturbances even in the early
      stages of the disease. (1) The investigators recently introduced a non-invasive technique to
      assess autonomic adrenergic fiber function using the quantitative pilomotor axon-reflex test
      (QPART). (2)

      OBJECTIVES Demonstrating generalizability and reliability of the QPART technique, the
      anticipated positive results of this protocol might lend support to the utility of QPART as a
      diagnostic tool. This might be of particular interest in clinical practice as the QPART
      technique has been shown to assess small fiber function with low variability and
      comparatively low technical effort whereas vasomotor assessment is limited by high
      variability and sudomotor assessment requires technical demanding settings. (3) Moreover, the
      anticipated positive correlation between functional and structural pilomotor nerve fiber
      impairment might support the capacity of the QPART technique to assess specific fiber damage
      and thus provide a non-invasive tool to 1.) study pilomotor nerve damage in research studies
      and 2.) allow for longitudinal clinical assessment in PD patients to monitor disease
      progression.

      ETHICAL STANDARD The study protocol has been approved by the institutional review board of
      Technische Universität Dresden (IRB study reference: EK349082015) as well as by the
      institutional review board of each participating site (Berlin accepted the protocol based on
      Technische Universität Dresden IRB approval; Budapest IRB number: 004513-004/2016/OTIG;
      Boston IRB number: 2016P000141)

      This study will be conducted according to the principles expressed in the Declaration of
      Helsinki. Written informed consent will be obtained from each study participant. The consent
      will be reviewed with the subject by one of the study physicians. The subject will sign the
      informed consent before any procedures pertaining to the study are initiated. A copy of the
      signed informed consent will be given to the participant and another copy kept on file.
      Conduction of this study will comply with the GCP (Good Clinical Practice) guidelines.

      STUDY PROCEDURES Quantitative Pilomotor Axon-Reflex Test (QPART): Iontophoresis of
      phenylephrine is used to induce axon-reflex mediated piloerection. A drug delivery capsule
      electrode (LI-611; Perimed®, Järfälla, Sweden) is affixed on the testing area on the dorsal
      forearm. The inner chamber of this capsule, open to the skin surface, is filled with 0.4ml of
      1 % phenylephrine solution. The drug delivery electrode is then connected to the
      iontophoresis stimulation box (Phoresor II-Auto-PM850; IOMED Inc., Salt Lake City, USA).
      Iontophoresis is performed over a 1cm diameter skin region with 0.5mA over 5 minutes.
      Silicone impressions of piloerection are obtained to create a local topographic map of
      piloerection. A silicone based two-phase material with high liquidity (Honigum Light, DMG,
      Hamburg, Germany) is placed over the skin for 10 seconds. The silicone cures for 5 minutes,
      has toner applied to mark the pilomotor impressions, excess toner is wiped free and the
      silicone is scanned to capture the image digitally. Silicone impressions of erect hair
      follicles are quantified by number and area and spatial spread. A high resolution scanner
      (Fuel 3D® Technologies Limited, Chinnor, United Kingdom) connected to a personal computer
      equipped with image analyzing software (Fuel3D® Studio Starter; Fuel 3D® Technologies
      Limited, Chinnor, United Kingdom) is used to quantify additionally the goosebump reaction.

      Sympathetic Skin Response (SSR): The skin conductance level (SCL) is measured in µSievert
      (µS) from two medial phalanges (index and third finger) with a Powerlab® polygraph (AD
      Instruments, Bella Vista, Australia). The maximum increase in amplitude following sudden deep
      respiration (Sympathetic Skin Response; SSR) is calculated to quantify the functional
      reactivity of sweat glands as previously described. (4)

      Quantitative Direct and Indirect Test of Sudomotor Function (QDIRT): Axon-reflex mediated
      sweating is measured after iontophoresis of 10% acetylcholine by drying the stimulated region
      on the volar aspect of the forearm and dusting with indicator dye (povidone-iodine and
      cornstarch) followed by repeated digital photographs taken every 15 seconds for 7 minutes
      with a 18 Megapixel camera (EOS 60D; Canon Inc., Tokyo, Japan) with 100-mm macro lens. Images
      are digitally analyzed for droplet number, size, and axon-reflex spread as previously
      described. (5)

      Evaluation of perceived motor and autonomic symptoms: Progression of motor and autonomic
      symptoms are assessed through validated symptom scores MDS-UPDRS motor part and SCOPA AUT.

      Skin biopsies: a-synuclein/PGP Ratio; Immunhistochemical staining for a-synuclein and
      intraepidermal nerve fibers will be performed in 3 skin punch biopsies obtained from the
      QPART testing sites and two control sites (lower legs). Three-millimeter biopsies will be
      obtained following local anesthesia with 2% lidocaine. Biopsy specimens will be fixed in
      Zamboni solution for 18 hours and cryoprotected overnight (20% glycerol and 20% 0.4 M
      Sorensen buffer). Skin blocks are cut using freezing microtome and 20 tissue sections are
      analyzed. 20 tissue sections will analyzed. Alpha synuclein/intraepidermal nerve fiber
      density ratios will be calculated.

      TIMELINE Subjects will be assessed for eligibility by a listed study physician. At baseline
      all subjects will undergo medical history, physical examination, QPART, SSR, QDIRT, MDS-UPDRS
      and SCOPA AUT assessment as described above. These testing procedures will be repeated, after
      1-2 weeks, 1 year, 2 years, and 3 years post-baseline. All testing will be performed in a
      temperature and humidity controlled environment. Only at Dresden-Site subjects will
      additionally undergo the skin punch biopsy procedure as described above at baseline, after 1
      year and after 3 years.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Male and female patients with early Parkinson's disease, gender matched healthy control
        subjects
      
Biospecimen description: 
      3mm skin biopsies (punch biopsies)
    
Keywords: Parkinson's disease; Autonomic; Diagnosis; Pilomotor; Alpha-synuclein; Axon-reflex; Peripheral nerve fibers