The rented equipment also may have been used on five patients in other states, The Boston Globe reported Wednesday.
The patients who underwent neurosurgery at Catholic Medical Center in Manchester have been notified they may have been exposed to Creutzfeldt-Jakob disease, hospital officials said at a news conference.
The officials said chances were very low the patients had been exposed to the disease.
The surgical procedures took place between May and August. The hospital issued the alert after officials discovered the instruments might have been contaminated with brain tissue for a patient who had surgery in May. The patient was diagnosed with the rare incurable disease last month.
A person may not display any symptoms for a year and up to several decades after exposure to the disease. The National Institutes of Health say it cannot be transmitted to other people through the air or human contact.
The usual method of sterilizing surgical equipment does not kill the proteins that cause the disease.