WARNING – DISTRESSING CONTENT: A young boy who was gravely injured while stopping a violent attack on his mother has died 19 months after the attacker caved in his skull.

Vanya Krapivin had returned home from school in May last year to find his neighbour Roman Pronin, a convicted murderer, standing over his terrified mother in their flat in Severodvinsk, northwest Russia.

The then 15-year-old found his injured mother, Natalie Krapivina, screaming on the floor.

The teenager picked up a three kilogram dumbbell and struck Pronin, who then wrestled the weight out of his hand and smashed Vanya over the head before fleeing the apartment.

Vanya Krapivin lost most of his frontal skull bone while trying to save his mother from their neighbour. Images: Twitter/VK.com More

Another neighbour discovered the pair in pools of blood before they were rushed to hospital.

Ms Krapivina had suffered 27 stab wounds while her son was placed in an induced coma for the next nine months. Surgeons also had to remove parts of his brain and most of his frontal skull bone.

His mother only visited her son a handful of times during his time in hospital. She said she could not bring herself to see him because she blamed herself for the attack.

One year on from the attack, Vanya started showing minor signs of improvement and in June 2018 he began to eat solid food before he was transferred to a rehabilitation centre in Moscow.

But sadly after contracting the flu two months ago, Vanya passed away in hospital on Tuesday.

Cronin was jailed for 14 years for their attempted murders and will now face a murder charge.