The authors discuss the differential diagnosis and treatment of so-called atypical blepharospasm (apraxia of opening of the eyelids) as one of the not infrequent possible failures of treatment of blepharospasm. Atypical blepharospasm (AB) differs from idiopathic blepharospasm in particular by the temporary inability to start opening of the eyelids and the absence of an obvious spasm of the m. orbicularis oculi which is typical for idiopathic blepharospasm. In the investigated group the authors used botulotoxin A injections for 5 years in a total of 17 patients with blepharospasm, incl. 5 with the atypical variety. The injections were directed to the place of pretarsal portion of m. orbicularis oculi. The injections were strictly medial and lateral - 2 on each upper eyelid - up to its border - i.e. to the site where the eyelashes originate. The therapeutic effect was very satisfactory in the whole group of patients and when the mentioned procedure was respected the results in the atypical variant did not differ from those in classical idiopathic blepharospasm. In the authors’ opinion the pathophysiological basis of the lesion in AB is a disorder of the normal reciprocal alternation of activity of the m. orbicularis oculi and the m. levator palpebrae supp., but only in its pretarsal portion.

        Key words: atypical blepharospasm, idiopathic blapharospasm, differential diagnosis, pathophysiolo- gy, treatment