Isolated Ophthalmoplegia: An Uncommon Presentation of Anti-glutamic Acid Decarboxylase 65 (Anti-GAD65) Neurological Syndrome

Isolated ophthalmoplegia as an anti-glutamic acid decarboxylase 65 (anti-GAD65) antibody-associated neurological syndrome is rare. We present a case of a 22-year-old pregnant Hispanic female patient who presented initially with a left oculomotor nerve palsy following an emergency department (ED) visit for migraine headache. Brain imaging was done with no important findings. The patient was managed with pyridostigmine as a myasthenia gravis diagnosis was suspected but no response was seen. Left oculomotor palsy went on to improve gradually with a course of oral steroids; however, on her third-month follow-up, the patient developed a worsening diplopia episode revealing a new left abducens nerve palsy followed by right oculomotor and trochlear nerve palsies in a period of less than one month. An autoimmune encephalitis panel was made which came back positive for anti-GAD65. A recommendation was made to start intravenous immunoglobulin (IVIG); however, the insurance company only approved mycophenolate mofetil which went on to mitigate the aforementioned palsies. Our case supports the efficacy of steroids and mycophenolate mofetil as reasonable immunomodulators for GAD65-associated neurological syndromes. However, further research is needed to determine the best appropriate treatment approach.