Donna Macdonald (39) and her daughter Shari (23) say they need more support to care for Shari's 21-month-old daughter, Shylyn.
This week is brain injury appeal and awareness week, and the national association, Brain Injury New Zealand, is emphasising the strain head injuries put on families and relationships.
Ms Macdonald, who works in administration at Dunedin Hospital's radiology department, said the family needed help.
Shylyn's grandmother, she was also her principal carer, as her daughter could not be left with Shylyn for more than an hour or two.
When Shari was 3, her frontal lobe was damaged in a car crash in which her skull was fractured.
Ms Macdonald said the head injury affected her daughter's judgement, her ability to assess risk and her ability to form healthy relationships.
Her stamina and short-term memory were also affected.
It was tough for Ms Macdonald working full-time, to then race home to feed and care for Shylyn.
Ms Macdonald also had a 13-year-old son, whom she was able to see less often these days.
Shylyn attends day-care during the day, while Shari attends a Salvation Army-run programme.
Ms Macdonald said she had no social life or contact with friends, and when she had "downtime" she just felt like sleeping.
Although she had known the head injury would impede her daughter's ability to mother her child, Ms Macdonald had not counted on being the main carer, and had hoped Shari could cope on her own with support.
Brain Injury Otago liaison officer Cathy Matthews said families tended to "normalise" a person's head injury because they grew used to it, and it could take a change in circumstances to realise how much it compromised the person's abilities.
Mrs Matthews said the association, which had recently become involved with the Macdonalds, was helping find extra support for the family, as it appeared they were not accessing everything to which they were entitled.
