ABSTRACT
A 28-year-old woman was admitted to the ENT Department of the Faculty of Medicine, Chiang Mai University because of left otitis externa, chronic mastoiditis and facial nerve palsy (lower motor neurone). Left radical mastoidectomy with wide debridement of granulation and necrotic tissue at ear canal, dura, sigmoid sinus, ossicle and facial nerve were done two weeks after admission. Multiple pus culture from the lesion revealed different types of organisms e.g. proteus mirabilis, beta strep non group A, and enterococci beta type. Several aminoglycosides were alternately given for two months without improvement of ear infection. She developed carpopedal spasm with hypocalcemia after three weeks of such treatment. Hypomagnesemia was recognized. Calcium and milk supplement gave temporary relief, but permanent relief was obtained after aminoglycoside was discontinued. Serum electrolyte had reversed to normal on follow-up.