Mills' syndrome and myasthenia gravis: a case report

A 50-year-old man with hypothyroidism was referred for refractory myasthenia gravis (MG). He developed progressive, painless right-sided shoulder and leg weakness, dysphagia, and fatigable diplopia. Acetylcholine receptor (AChR) antibodies were positive. Immunosuppressive therapies provided only transient improvement in oculo-bulbar symptoms, while hemiparesis progressed. Examination showed fatigable ptosis with curtain sign, vertical gaze limitation, and diplopia localizing to left lateral rectus weakness. Upper motor neuron signs included brisk masseteric reflex, right spastic hemiparesis, and hyperreflexia. EMG demonstrated chronic reinnervation in right cervical and lumbosacral regions. MRI revealed T2 hyperintensity in the left upper cervical cord and adjacent medulla without enhancement. A diagnosis of AChR+ MG and Mills' syndrome was made. While MG has previously been reported to coexist with ALS, this is the first known case associated with Mills' syndrome. This highlights the importance of recognizing overlapping autoimmune and neurodegenerative disorders and the need for further research into shared mechanisms.