Small-Fiber Neuropathy in Pompe Disease: First Reported Cases and Prospective Screening of a Clinic Cohort

Case series Patient: Male, 11 • Female, 49 Final Diagnosis: Small fiber neuropathy Symptoms: — Medication: — Clinical Procedure: Skin biopsy Specialty: Neurology OBJECTIVE: Unusual clinical course BACKGROUND: Prior autopsy reports demonstrate glycogen deposition in Schwann cells of the peripheral nerves in patients with infantile and late-onset Pompe disease (LOPD), but little is known about associated clinical features. CASE REPORT: Here, we report the first confirmed cases of small-fiber neuropathy (SFN) in LOPD and present the results of a first attempt at screening for SFN in this patient population. After confirming small-fiber neuropathy in 2 LOPD patients, 44 consecutive Pompe patients (iOPD=7, LOPD n=37) presenting to the Duke University Glycogen Storage Disease Program between September 2013 and November 2014 were asked to complete the 21-item Small-Fiber Neuropathy Screening List (SFNSL), where a score of ≥11 is considered to be a positive screen. Fifty percent of patients had a positive SFN screen (mean score 11.6, 95% CI 9.0–14.2). A modest correlation between the SFNSL score and current age was seen (r=0.38, p=0.01), along with a correlation with duration of ERT (r=0.31, p=0.0495). Trends toward correlation with forced vital capacity and age at diagnosis were also present. Women had a higher mean SFNSL score (14.2) than men (8.2, p=0.017). CONCLUSIONS: SFN may occur in association with Pompe disease and precede the diagnosis. Further studies are needed to determine its true prevalence and impact.