Abstract Details

Title Small Fiber Neuropathy Incidence, Prevalence, Longitudinal Impairments, and Disability

Topic Neuromuscular and Clinical Neurophysiology (EMG)

Presentation(s) P10 - Poster Session 10 (8:00 AM-9:00 AM)

Poster/Presentation
Number 11-005

Background

Limited population-based data on SFN epidemiology, comorbidities, longitudinal impairments, and disabilities exists.

Objective

To determine small fiber neuropathy (SFN) incidence, prevalence, comorbidities, longitudinal impairments, and disabilities.

Design/Methods

Test-confirmed patients with SFN in Olmsted, Minnesota and adjacent counties were compared 3:1 to matched controls over 20 years.

Results

Ninety-four patients with SFN were identified, incidence 1.3/100,000/year increasing over the study period, prevalence 13.3/100,000. Average follow-up was 6.1 years (0.7-43 years), mean onset age 54 years (range 14–83). Female (67%), obesity (BMI mean 30.4 versus 28.5), insomnia (86% versus 54%), analgesic-opioid prescriptions (72% versus 46%), hypertriglyceridemia (180 mg/dl mean versus 147 mg/dl) and diabetes mellitus (DM) (51% versus 22%, p<0.001) were more common (OR 3.8-9.0, all p<0.03). Higher Charlson comorbidities (median 6, range 3-9) occurred versus controls (median 3, range 1-9) p<0.001. Myocardial infarctions occurred in 46% versus 27% of controls (p<0.0001). Classifications included: idiopathic (70%); DM (15%); Sjögrens (2%); AL-amyloid (1%); transthyretin-amyloid (1%); Fabry (1%); lupus (1%); post viral (1%); Lewy body (1%) and multifactorial (5%). Large fiber neuropathy developed in 36%, on average 5.3 years (range 0.2-14.3 years) from SFN onset. Median onset Composite Autonomic Severity Score (CASS) was 3, change/year 0.08 (range 0-2.0). Median Neuropathy Impairment Score (NIS) was 2 at onset (range 0 to 8), change/year +1.0 (range -7.9 to +23.3). NIS and CASS change >+1 point/year occurred in only AL-amyloid, hereditary transthyretin-amyloid, Fabry, uncontrolled DM, and Lewy body. Death from symptom onset was higher in patients with SFN 19% versus controls 12%.

Conclusions

Isolated SFN is uncommon but increasing in incidence. Most patients do not develop major neurological impairments and disability but have multiple comorbidities, including cardiovascular ischemic events, and increased mortality. Development of large fiber involvements and DM are common over time. Targeted testing can identify treatable etiologies.

Authors/Disclosures
Stephen A. Johnson, MD (Mayo Clinic) PRESENTER	The institution of Dr. Johnson has received research support from ALS Association.
Kamal Shouman, MD (Mayo Clinic)	The institution of Dr. Shouman has received research support from dysautonomia international.
Shahar Shelly, MD (Rambam Medical Center)	Dr. Shelly has nothing to disclose.
Paola Sandroni, MD, PhD, FAAN (Mayo Clinic)	Dr. Sandroni has nothing to disclose.
Sarah E. Berini, MD (Mayo Clinic)	Dr. Berini has nothing to disclose.
P. James B. Dyck, MD, FAAN (Mayo Clinic)	Dr. Dyck has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Akcea/Ionis.
E. M. Hoffman, DO, PhD (Mayo Clinic, Neurology)	Dr. Hoffman has nothing to disclose.
Jayawant N. Mandrekar, PhD	Dr. Mandrekar has nothing to disclose.
Zhiyv Niu, PhD, FACMG (Mayo Clinic)	Zhiyv Niu has nothing to disclose.
Christopher Lamb, MD (Mayo Clinic)	Dr. Lamb has received research support from Immunovant, Inc.
Phillip A. Low, MD, FAAN (Mayo Clinic)	Dr. Low has nothing to disclose.
Wolfgang Singer, MD (Mayo Clinic)	Dr. Singer has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Amneal. Dr. Singer has received personal compensation in the range of $500-$4,999 for serving as a Consultant for UniQure. Dr. Singer has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Biohaven. Dr. Singer has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Theravance. 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.
Michelle L. Mauermann, MD, FAAN (Mayo Clinic)	The institution of Dr. Mauermann has received research support from IONIS. The institution of Dr. Mauermann has received research support from Alnylam. Dr. Mauermann has received publishing royalties from a publication relating to health care.
John R. Mills, MD, PhD (Mayo Clinic)	The institution of Dr. Mills has received research support from Werfen Diagnostics. Dr. Mills has received intellectual property interests from a discovery or technology relating to health care.
Divyanshu Dubey, MD, FAAN (Mayo Clinic)	The institution of Dr. Dubey has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Argenx. The institution of Dr. Dubey has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Arialys. The institution of Dr. Dubey has received personal compensation in the range of $500-$4,999 for serving as a Consultant for UCB . Dr. Dubey has received research support from Department of Defense . Dr. Dubey has received research support from Department of Defense . Dr. Dubey has received research support from UCB. Dr. Dubey has received research support from David J. Tomassoni ALS Research Grant Program . Dr. Dubey has received intellectual property interests from a discovery or technology relating to health care. Dr. Dubey has received intellectual property interests from a discovery or technology relating to health care. Dr. Dubey has received intellectual property interests from a discovery or technology relating to health care. Dr. Dubey has received intellectual property interests from a discovery or technology relating to health care.
Nathan P. Staff, MD, PhD, FAAN (Mayo Clinic)	Dr. Staff has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Stem Cell Research & Therapy. Dr. Staff has received research support from National Institutes of Health.
Christopher J. Klein, MD, FAAN (Mayo Clinic)	Dr. Klein has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Takeda. Dr. Klein has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Sangamo Therapeutics . Dr. Klein has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Faze Medicine .