Third cranial nerve palsy or pseudo 3rd nerve palsy of myasthenia gravis? A challenging diagnosis in systemic lupus erythematosus

Diplopia is frequently encountered in neurological practice and may occur as part of the clinical spectrum of 3rd cranial nerve palsy. Correct localization of the underlying problem is the first step in making an accurate diagnosis. Pathologies affecting the supranuclear structures, cranial nerves and nuclei, extraocular muscles and the neuromuscular junction may cause or simulate 3rd nerve palsy. We report a case of a patient with longstanding quiescent SLE who presented with sudden onset of diplopia and discuss possible aetiologies including ischemia, demyelination, neuromuscular conditions and medication-induced.