Objective: To describe finding of various neurophysiologic tests in patients with mucopolysaccharidosis III (MPS III) early in the disease course.
Methods: Patients were evaluated with flash visual evoked potentials (VEP), brainstem auditory evoked potentials (BAEP), electroencephalography (EEG), and nerve conduction studies (NCS) before they underwent hematopoietic stem cell transplantation (HSCT).
Results: Thirteen children underwent at least one neurophysiologic test before HSCT. The mean age at testing was 2.7 years. Ten of 11 (91%) patients had a normal flash VEP, and all 9 who had BAEP had normal central conduction. EEG was normal in 7/13 (54%), with the others showing diffuse slowing. NCS was normal in 10/11 (91%) patients.
Conclusions: Despite extensive central nervous system involvement in MPS III, flash VEP and BAEP are almost always normal. EEG is often abnormal early in the disease.
Significance: This is the first report of neurophysiologic tests in a large series of MPS III patients.