Specific phobia is a frequent non-motor feature in stiff man syndrome

Objective: To investigate systematically the rate and type of phobia in stiff man syndrome and its variants, and to compare patients with stiff man syndrome with and without phobia for sociodemographic and neurological characteristics. Methods: 43 consecutive patients with stiff man syndrome referred to a university department of neurology were assessed using the anxiety disorders interview schedule, revised (ADIS-R), a structured diagnostic interview for anxiety disorders, in addition to a full clinical neurological and psychiatric assessment. Results: 19 patients (44.2%) developed task specific phobia-that is, fear and avoidance of situations difficult to master owing to the motor symptoms of stiff man syndrome (such as crossing streets). Three further patients (7%) had subthreshold phobia-that is, phobic anxiety without avoidance. There were no significant differences between patients with and without phobia in terms of age, illness duration, type of stiff man syndrome, antibody status, or frequency of falls. Patients with phobia were more likely to present with exaggerated startle responses and to have an initial misdiagnosis of psychogenic movement disorder. Conclusions: Specific phobia is a frequent non-motor symptom of stiff man syndrome. Early recognition is an important aid to correct diagnosis. The aetiology of phobia in stiff man syndrome is unknown. There is no evidence of a direct pathogenic role of autoantibodies directed against glutamic acid decarboxylase in the development of phobia.