Chiari 1 malformation presenting as strabismus.

Introduction: Strabismus has been previously reported as a rare presenting feature of the Type 1 Chiari malformation.

Case reports: We report a case series of twelve patients with Chiari 1 malformations with either strabismus or diplopia as part of their initial presentation. Ten patients had diplopia at the time of presentation, while 2 young children (ages 2 and 6) presented with esotropia without complaints of diplopia. Of the 10 patients with diplopia, 7 were constantly or frequently tropic while 3 had symptomatic phorias. One or more unusual features of the strabismus led to further investigations and the diagnosis of Chiari in these patients. The most common oculomotor disturbance was a comitant esotropia. Most patients were managed with prism glasses. One patient had strabismus surgery as primary treatment with early orthotropia. Three patients underwent neurosurgical decompression, with minimal improvement of their strabismus; one of these underwent subsequent successful strabismus surgery.

Conclusions: Chiari 1 malformation may present with strabismus or diplopia as the major finding. Associated neurological features may be nonspecific (e.g., headache), subtle (e.g., gaze-evoked nystagmus), or delayed. Although neurosurgery may be required in some cases, primary strabismus management (surgical or prismatic correction) can be successful, particularly when strabismus is the lone (or sole specific) finding.