Prolonged administration of streptomycin may result in damage to the:

Streptomycin (antitubercular) causes vestibular damage on prolonged use. Adverse effects This class of drugs is notorious for their adverse effects like ototoxicity and nephrotoxicity. About 1/5th patients given streptomycin 1 gm BD i.m. experience vestibular disturbances although auditory disturbances are less common.  Streptomycin has the lowest nephrotoxicity among aminoglycosides; probably because it is not concentrated in the renal cortex. Reference: Essentials of Medical Pharmacology Eighth Edition KD TRIPATHI page no 94,798