Unilateral third nerve palsy caused by Guillain-Barré Syndrome

Background: Highly asymmetric clinical signs in a patient suggest the need for caution in making the diagnosis of Guillain-Barré Syndome (GBS). Methods: Case report and literature review. We present a case of strictly unilateral left third cranial nerve palsy in a patient with GBS, review other highly asymmetrical cranial nerve palsies previously reported in this condition, and suggest an appropriate alternative differential diagnosis. Conclusion: Unilateral third cranial nerve palsy is an exceptionally rare manifestation of GBS, expanding the spectrum of clinical signs and neuraxis involvement that may be seen in the condition.