Assessment of autonomic dysfunction of multiple system atrophy with laryngeal abductor paralysis as an early manifestation

Laryngeal abductor palsy (LAP) is common in the advanced stages of multiple system atrophy (MSA). However, occurrence of LAP in the early stages might make a diagnosis of MSA difficult. To search for a clue to diagnosis of MSA with LAP as an early manifestation, we assessed the clinical features of autonomic dysfunction and the central cardiovascular control circuits in two MSA patients who had LAP as a cardinal symptom in the early stages. Development of autonomic dysfunction was preceded or followed by LAP. The autonomic symptom occurring predominantly in the earliest stages was urinary disturbance rather than orthostatic hypotension. Although screening cardiovascular autonomic function tests did not conclusively indicate a diagnosis of MSA, vasopressin release in response to head-up tilt and growth hormone response to clonidine administration demonstrated inappropriate responses, suggesting that the noradrenergic neurons of the caudal ventrolateral medulla were impaired. Diagnosis of atypical MSA with LAP in the early stages might be accelerated by a detailed investigation focused on urinary symptoms and neuroendocrine approaches.