Abstract Details

Title Clinical and Autonomic Features Suggest Phenoconversion from Sporadic Adult-onset Ataxia to Clinically Probable Multiple System Atrophy

Topic Movement Disorders

Presentation(s) P6 - Poster Session 6 (8:00 AM-9:00 AM)

Poster/Presentation
Number 3-019

Objective To determine factors that predict phenoconversion from sporadic adult-onset ataxia (SAOA) to multiple system atrophy (MSA).

Background Sporadic adult-onset ataxia (SAOA) is a neurodegenerative cerebellar disease that causes progressive ataxia excluding other causes, including neurodegenerative ataxia such as multiple system atrophy (MSA). Some SAOA patients later develop autonomic failure to meet diagnostic criteria for MSA. Identifying risk factors in SAOA patients for developing MSA poses benefits for early diagnosis and future early intervention.

Design/Methods We performed a retrospective review of all patients referred for ataxia of unknown etiology initially diagnosed with SAOA from 1999 to 2018 at Mayo Clinic, Minnesota. Patients later diagnosed with MSA were classified as phenoconverters. Clinical variables, demographic information, and autonomic function studies were analyzed to assess factors that predicted later diagnosis of MSA.

Results

Among 169 patients with SAOA at presentation, 60 (35.5%) phenoconverted to MSA. Clinical features influencing phenoconversion to MSA included: early autonomic symptoms, stridor, bladder symptoms, REM sleep disorder, and orthostatic intolerance. MSA phenoconverters more likely endorsed REM sleep disorder (38.3%) compared to nonconverters (11.9%). Age of onset, parkinsonism, and falls remained similar between the two groups. More patients with MSA underwent autonomic function tests (70% vs 41.3%) and thermoregulatory sweat tests (58.3% vs 33%) compared to the SAOA group.

On autonomic testing, phenoconverters had higher supine systolic blood pressures with greater orthostatic drop and higher median composite autonomic severity scores. There was a similar rate of abnormal thermoregulatory sweat tests between MSA (75%) and SAOA (68.8%) groups while MSA phenoconverters had higher mean percentages of anhidrosis (31.2%) than the SAOA group (13.9%).

Conclusions Our findings suggest that at least a third of SAOA patients phenoconvert to MSA. While these results are limited due to the retrospective nature, presenting clinical features and autonomic function tests may be helpful to identify SAOA patients likely to develop MSA.

Authors/Disclosures
Tina Liu, MD PRESENTER	Dr. Liu has nothing to disclose.
Monica K. Johnson, MD	Dr. Johnson has a non-compensated relationship as a Advisory Board Member with LiveOn OPO that is relevant to AAN interests or activities.
Negin Badihian, MD	Dr. Badihian has nothing to disclose.
William Harmsen (Mayo Clinic)	William Harmsen has nothing to disclose.
Lauren Jackson, MD (Mayo Clinic)	Dr. Jackson has nothing to disclose.
Mariana Suarez	No disclosure on file
Eduardo E. Benarroch, MD, FAAN (Mayo Clinic)	Dr. Benarroch has nothing to disclose.
Paola Sandroni, MD, PhD, FAAN (Mayo Clinic)	Dr. Sandroni has nothing to disclose.
Phillip A. Low, MD, FAAN (Mayo Clinic)	Dr. Low has nothing to disclose.
Wolfgang Singer, MD, FAAN (Mayo Clinic)	Dr. Singer has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Biohaven. The institution of Dr. Singer has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Lundbeck. Dr. Singer has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Ionis. Dr. Singer has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Yoda. Dr. Singer has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Theravance. Dr. Singer has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Ferrer. The institution of Dr. Singer has received research support from NIH. The institution of Dr. Singer has received research support from FDA. The institution of Dr. Singer has received research support from Michael J. Fox Foundation. Dr. Singer has received intellectual property interests from a discovery or technology relating to health care.
Elizabeth A. Coon, MD, FAAN (Mayo Clinic)	Dr. Coon has received publishing royalties from a publication relating to health care. Dr. Coon has a non-compensated relationship as a Non-Voting Member of the Board of Directors with UCNS that is relevant to AAN interests or activities.

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