The child was rushed to hospital following the attack, which happened while it was in the care of Connor James Hume.
While at hospital, doctors identified a bleed on the baby’s brain and carried out emergency surgery to relieve the pressure.
The baby spent several weeks in intensive care before being discharged. As a result of the severe injuries sustained during the incident, the child is now blind, has cerebral palsy, is unable to walk or talk and requires 24-hour care.
Hume, who was 18 at the time of the incident, was charged with causing or allowing serious physical harm to a child.
The now 22-year-old, of Ashdale Road, Consett, denied the offence but was found guilty following a trial and sentenced to eight years and ten months in prison.
Detective Chief Superintendent Adrian Green, from Durham Constabulary, led the investigation. He said: “I am pleased that, after the persistence of a very professional and dedicated investigation team, someone has finally been brought to justice for the horrific injuries and suffering caused to this baby.”