Subclinical autonomic dysfunction in spinobulbar muscular atrophy (Kennedy disease)

Introduction: Spinobulbar muscular atrophy (SBMA) is an inherited adult-onset motor neuron disease caused by the expansion of a polyglutamine tract within the androgen receptor. Autonomic nervous system involvement (ANS) is not considered part of SBMA. The aim of this study was to assess autonomic cardiovascular function in 5 SBMA patients. Methods: Five quantitative autonomic function tests (AFTs) were performed in 5 SBMA patients. Plasma noradrenaline (NA) concentration in patients and in 5 healthy subjects was also measured. Results: AFTs were abnormal in 4 of the 5 patients, and plasma NA concentration was significantly reduced in patients with respect to controls. Conclusion: The impairment of cardiovascular responses to AFTs in addition to reduced plasma NA concentration observed in our patients suggests subclinical involvement of the ANS in Kennedy disease.